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www.motorola.com/semiconductors dl200/d rev. 5, 01/2003 sensor device data book f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
ii data classification product preview this heading on a data sheet indicates that the device is in the formative stages or in design (under development). the disclaimer at the bottom of the first page reads: athis document contains information on a product under develop- ment. motorola reserves the right to change or discontinue this product without notice.o advance or preliminary information this heading on a data sheet indicates that the device is in sampling, preproduction, or first production stages. the disclaimer at the bottom of the first page reads: athis document contains information on a new product. specifications and information herein are subject to change without notice.o fully released a fully released data sheet contains neither a classification heading nor a disclaimer at the bottom of the first page. this document contains information on a product in full production. guaranteed limits will not be changed without written notice to your local motorola semiconductor sales office. motorola device classifications in an effort to provide up-to-date information to the customer regarding the status of any given device, motorola has classified all devices into three categories: preferred devices, current products and not recommended for new design products. a preferred type is a device which is recommended as a first choice for future use. these devices are apreferredo by virtue of their performance, price, functionality, or combination of attributes which offer the overall abesto value to the customer. this category contains both advanced and mature devices which will remain available for the fore- seeable future. preferred devices in the data sheet sections are identified as a amotorola preferred device.'' device types identified as acurrento may not be a first choice for new designs, but will continue to be available because of the popularity and/or standardization or volume usage in current production designs. these products can be acceptable for new designs but the preferred types are considered better alternatives for long term usage. any device that has not been identified as a apreferred deviceo is a acurrento device. products designated as anot recommended for new designo may become obsolete as dictated by poor market acceptance, or a technology or package that is reaching the end of its life cycle. devices in this category have an uncertain future and do not represent a good selection for new device designs or long term usage. the sensor data book does not contain any anot recommended for new designo devices. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
iii device data book the information in this book has been carefully reviewed and is believed to be accurate; however, no responsibility is assumed for inaccuracies. furthermore, this information does not convey to the purchaser of semiconductor devices any license under the patent rights to the manufacturer. motorola reserves the right to make changes without further notice to any products herein. motorola makes no war- ranty, representation, or guarantee regarding the suitability of its products for any particular purpose, nor does motoro- la assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation consequential or incidental damages. atypicalo parameters can and do vary in different applications and actual performance may vary over time. all operating parameters, including atypicalso, must be validated for each customer application by customer's technical experts. motorola does not convey any license under its patent rights nor the rights of others. motorola products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body, or other applications intended to support or sustain life, or for any other application in which the failure of the motorola product could create a situation where personal injury or death may occur. should buyer purchase or use motorola products for any such unintended or un- authorized application, buyer shall indemnify and hold motorola and its officers, employees, subsidiaries, affiliates, and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized use, even if such claim alleges that motorola was negligent regarding the design or manufacture of the part. motorola and the stylized m logo are registered in the us patent & trademark office. all other product or service names are the property of their respective owners. motorola, inc. is an equal opportunity/affirmative action employer. 5th edition ? motorola, inc. 2003 aall rights reservedo printed in u.s.a. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
iv f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
v table of contents section one e general information quality and reliability 12 . . . . . . . . . . . . . . . . . . . . . . . . . . . overview 12 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . reliability issues for silicon pressure sensors 13 . . . . . . soldering precautions 110 . . . . . . . . . . . . . . . . . . . . . . . . . . pressure sensors 111 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . electrostatic process control 117 . . . . . . . . . . . . . . . . . . statistical process control 111 . . . . . . . . . . . . . . . . . . . . . . test results 117 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . accelerometer 117 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . media compatibility overview 118 . . . . . . . . . . . . . . . . . . . section two e acceleration sensor products mini selector guide 22 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . device numbering system 22 . . . . . . . . . . . . . . . . . . . . . . . sensor applications 23 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . acceleration sensor faq's 24 . . . . . . . . . . . . . . . . . . . . . . . data sheets mma1200d 2 5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mma1201p 212 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mma1220d 2 18 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mma1250d 224 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mma1260d 230 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mma1270d 236 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mma2201d 2 42 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mma2202d 2 48 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mma3201d 2 55 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . application notes an1559 application considerations for a switched capacitor accelerometer 2 62 . . . . . . . . . . . . . an1611 impact and tilt measurement using accelerometer 265 . . . . . . . . . . . . . . . . . . an1612 shock and mute pager applications using accelerometer 277 . . . . . . . . . . . . . . . . . . an1632 mma1201p product overview and interface considerations 2 84 . . . . . . . . . . an1635 baseball pitch speedometer 2 89 . . . . . . . . . . . . an1640 reducing accelerometer susceptibility to bci 2101 . . . . . . . . . . . . . . . . . an1925 using the motorola accelerometer evaluation board 2 104 . . . . . . . . . . . . . . . . . . . case outlines 2107 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . glossary of terms 2109 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . section three e pressure sensor products mini selector guide 32 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . device numbering system 34 . . . . . . . . . . . . . . . . . . . . . . . package offerings 35 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . orderable part numbers 36 . . . . . . . . . . . . . . . . . . . . . . . . . pressure sensor overview general information 37 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . motorola pressure sensors 38 . . . . . . . . . . . . . . . . . . . . . . integration 312 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . sensor applications 313 . . . . . . . . . . . . . . . . . . . . . . . . . . . pressure sensor faq's 314 . . . . . . . . . . . . . . . . . . . . . . . . data sheets mpx10, mpxv10gc series 315 . . . . . . . . . . . . . . . . . . . . mpx12 series 319 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mpx2010, mpxv2010g series 323 . . . . . . . . . . . . . . . . . mpx2050 series 327 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mpx2053, mpxv2053g series 331 . . . . . . . . . . . . . . . . . mpx2100 series 335 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mpx2102, mpxv2102g series 339 . . . . . . . . . . . . . . . . . mpx2200 series 343 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mpx2202, mpxv2202g series 347 . . . . . . . . . . . . . . . . . mpx2300dt1, mpx2301dt1 351 . . . . . . . . . . . . . . . . . . . mpx4080d 354 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mpx4100 series 359 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mpx4100a, mpxa4100a series 364 . . . . . . . . . . . . . . . . mpx4101a mpxa4101a, mpxh6101a series 370 . . . . mpx4105a series 375 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mpx4115a, mpxa4115a series 379 . . . . . . . . . . . . . . . . . mpx4200a series 384 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mpx4250a, mpxa4250a series 388 . . . . . . . . . . . . . . . . mpx4250d series 393 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mpx5010, mpxv5010g series 397 . . . . . . . . . . . . . . . . . mpx5050, mpxv5050g series 3103 . . . . . . . . . . . . . . . . mpx5100 series 3108 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mpx53, mpxv53gc series 3114 . . . . . . . . . . . . . . . . . . . mpx5500 series 3118 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mpx5700 series 3122 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mpx5999d 3126 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mpxa6115a, mpxh6115a 3130 . . . . . . . . . . . . . . . . . . . . mpxaz4100a series 3135 . . . . . . . . . . . . . . . . . . . . . . . . . mpxaz4115a series 3140 . . . . . . . . . . . . . . . . . . . . . . . . . mpxaz6115a series 3145 . . . . . . . . . . . . . . . . . . . . . . . . . mpxc2011dt1, mpxc2012dt1 3150 . . . . . . . . . . . . . . . mpxh6300a series 3153 . . . . . . . . . . . . . . . . . . . . . . . . . . mpxm2010 series 3158 . . . . . . . . . . . . . . . . . . . . . . . . . . . mpxm2053 series 3161 . . . . . . . . . . . . . . . . . . . . . . . . . . . mpxm2102 series 3164 . . . . . . . . . . . . . . . . . . . . . . . . . . . mpxm2202 series 3167 . . . . . . . . . . . . . . . . . . . . . . . . . . . mpxv4006g series 3170 . . . . . . . . . . . . . . . . . . . . . . . . . . mpxv4115v series 3174 . . . . . . . . . . . . . . . . . . . . . . . . . . . mpxv5004g series 3179 . . . . . . . . . . . . . . . . . . . . . . . . . . mpxv6115vc6u 3183 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . application notes an935 compensating for nonlinearity in the mpx10 series pressure transducer 3188 . . . an936 mounting techniques, lead forming and testing of motorola's mpx series mpx10 series pressure sensors 3195 . . . . . . an1082 simple design for a 320 ma transmitter interface using a motorola pressure sensor 3200 . . . . . . . . . . . . . . . . . . . . (continued e next page) f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
vi table of contents (continued) section three (continued) an1097 calibrationfree pressure sensor system 3203 . . . . . . . . . . . . . . . . . . . . . . an1100 analog to digital converter resolution extension using a motorola pressure sensor 3208 . . . . . . . . . . . . . . . . . . . . an1303 a simple 320 ma pressure transducer evaluation board 3211 . . . . . . . . . an1304 integrated sensor simplifies bar graph pressure gauge 3214 . . . . . . . . . . . . . . . an1305 an evaluation system for direct interface of the mpx5100 pressure sensor with a microprocessor 3219 . . . . . . . . . an1309 compensated sensor bar graph pressure gauge 3235 . . . . . . . . . . . . . . . . . . . . . an1315 an evaluation system interfacing the mpx2000 series pressure sensors to a microprocessor 3242 . . . . . . . . . . . . . . . . . . an1316 frequency output conversion for mpx2000 series pressure sensors 3263 . . . . an1318 interfacing semiconductor pressure sensors to microcomputers 3269 . . . . . . . . . . . an1322 applying semiconductor sensors to bar graph pressure gauges 3279 . . . . . . . . . . an1325 amplifiers for semiconductor pressure sensors 3284 . . . . . . . . . . . . . . . . . . . an1326 barometric pressure measurement using semiconductor pressure sensors 3288 . . . . . . . . . . . . . . . . . . . an1513 mounting techniques and plumbing options of motorola's mpx series pressure sensors 3297 . . . . . . . . . . . . . . . . . . . an1516 liquid level control using a motorola pressure sensor 3301 . . . . . . . . . . . . an1517 pressure switch design with semiconductor pressure sensors 3306 . . . . . an1518 using a pulse width modulated output with semiconductor pressure sensors 3312 . . . . . . . . . . . . . . . . . . . an1525 the abc's of signalconditioning amplifier design for sensor applications 3318 . . . . . . . . . . . . . . . . . . an1536 digital boat speedometers 3325 . . . . . . . . . . . . . an1551 low pressure sensing with the mpx2010 pressure sensor 3337 . . . . . . . . . . . an1556 designing sensor performance specifications for mcubased systems 3346 . . . . . . . . . . . . . . . . an1571 digital blood pressure meter 3355 . . . . . . . . . . . . an1573 understanding pressure and pressure measurement 3363 . . . . . . . . . . . an1586 designing a homemade digital output for analog voltage output sensors 3368 . . . . . an1636 implementing auto zero for integrated pressure sensors 3375 . . . . . . . . . . an1646 noise considerations for integrated pressure sensors 3378 . . . . . . . . . . . . . . . . . . . an1660 compound coefficient pressure sensor pspice models 3384 . . . . . . . . . . . . . . . . . . . . . an1668 washing appliance sensor selection 3390 . . . . . an1950 water level monitoring 3395 . . . . . . . . . . . . . . . . . an4007 new small amplified automotive vacuum sensors a single chip sensor solution for brake booster monitoring 3413 . . . . . . . . . . an4010 lowpressure sensing using mpx2010 series pressure sensors 3418 . . . . case outlines 3423 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . reference information reference tables 3439 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mounting and handling suggestions 3441 . . . . . . . . . . . . standard warranty clause 3442 . . . . . . . . . . . . . . . . . . . . . glossary of terms 3443 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . symbols, terms, and definitions 3446 . . . . . . . . . . . . . . . section four e safety and alarm integrated circuits mini selector guide 42 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . data sheets mc144671 4 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mc14468 4 9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mc14578 4 15 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mc14600 419 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mc145010 4 24 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mc145011 4 34 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mc145012 4 44 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mc145017 454 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mc145018 4 60 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . application notes an1690 alarm ic general applications overview 4 66 . . . . . . . . . . . . . . . . . . . . . . . . . . . an4009 alarm ic sample applications 470 . . . . . . . . . . . . case outlines 472 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . section five e alphanumeric device index alphanumeric device index 52 . . . . . . . . . . . . . . . . . . . . . . f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
11 motorola sensor device data www.motorola.com/semiconductors

section one introduction: this version of the sensor products device data hand- book is organized to provide easy reference to sensor device information. we have reorganized the book based upon your recommendations with our goal to make designing in pres- sure, acceleration and safety and alarm ics easy, and if you do have a question, you will have access to the technical support you need. the handbook is organized by product line, acceleration, pressure and safety and alarm ics. once in a section, you will find a glossary of terms, a list of frequently asked ques- tions or other relevant data. if you have recommendations for improvement, please complete the comment card and return it to us or, feel free to call our sensor device data handbook hot line and we will pers onally record your comments. the hot line number is 480/4133333. we look forward to hear- ing from you! quality and reliability 12 . . . . . . . . . . . . . . . . . . . . . . . overview 12 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . reliability issues for silicon pressure sensors 13 . . . . soldering precautions 110 . . . . . . . . . . . . . . . . . . . . . . . . pressure sensors 111 . . . . . . . . . . . . . . . . . . . . . . . . . . . electrostatic process control 111 . . . . . . . . . . . . . . . . statistical process control 113 . . . . . . . . . . . . . . . . . . . . test results 117 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . accelerometer 117 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . media compatability overview 118 . . . . . . . . . . . . . f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
12 motorola sensor device data www.motorola.com/semiconductors quality and reliability e overview a major objective of the production cycle from rigid incoming inspection of piece parts and materials, to stringent outgoing quality verification, the motorola assembly and process flow is encompassed by an elaborate system of test and inspection stations; stations to ensure a step-by-step adherence to prescribed procedure. this produces the high level of quality for which motorola is known . . . from start to finish. as illustrated in the process flow overview, every major manufacturing step is followed by an appropriate in-process quality inspection to insure product conformance to specification. in addition, statistical process control (s.p.c.) techniques are utilized on all critical processes to insure processing equipment is capable of producing the product to the target specification while minimizing the variability. quality control in wafer processing, assembly, and final test impart motorola sensor products with a level of reliability that easily exceeds almost all industrial, consumer, and military requirements. compensated sensor flow chart laser i.d. binning check initial oxidation p+ photo resist p+ diffusion resistor photo resist cavity photo resist die sort and load gel fill and cure resistor implant thin-film metal dep. wafer final visual cell marking 100% functional test emitter photo resist thin-film metal p.r. class probe die bond and cure final visual emitter diffusion contact photo resist wafer to wafer bond wirebond pack and ship final oxidation front metal 1234 5 67 9 10 11 13 15 16 17 18 19 20 21 22 23 8 metal photo resist 12 cavity etch 14 saw and wash laser trim f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
13 motorola sensor device data www.motorola.com/semiconductors reliability issues for silicon pressure sensors by theresa maudie and bob tucker sensor products division revised june 9, 1997 abstract reliability testing for silicon pressure sensors is of greater importance than ever before with the dramatic increase in sensor usage. this growth is seen in applica- tions replacing mechanical systems, as well as new designs. across all market segments, the expectation for the highest reliability exists. while sensor demand has grown across all of these segments, the substantial increase of sensing applications in the automotive arena is driving the need for improved reliability and test capability. the purpose of this paper is to take a closer look at these reli- ability issues for silicon pressure sensors. introduction discussing reliability as it pertains to semiconductor elec- tronics is certainly not a new subject. however, when devel- oping new technologies like sensors how reliability testing will be performed is not always obvious. pressure sensors are an intriguing dilemma. since they are electromechanical devices, different types of stresses should be considered to insure the different elements are exercised as they would be in an actual application. in addition, the very different package outlines relative to other standard semiconductor packages require special fixtures and test set-ups. however, as the sensor marketplace continues to grow, reliability testing becomes more important than ever to insure that products being used across all market segments will meet reliability lifetime expectations. reliability definition reliability is [1] the probability of a product performing its intended function over its intended lifetime and under the operating conditions encountered. the four key elements of the definition are probability, performance, lifetime, and operating conditions. probability implies that the reliability lifetime estimates will be made based on statistical tech- niques where samples are tested to predict the lifetime of the manufactured products. performance is a key in that the sample predicts the performance of the product at a given point in time but the variability in manufacturing must be controlled so that all devices perform to the same functional level. lifetime is the period of time over which the product is intended to perform. this lifetime could be as small as one week in the case of a disposable blood pressure transducer or as long as 15 years for automotive applications. environ- ment is the area that also plays a key role since the oper- ating conditions of the product can greatly influence the reliability of the product. environmental factors that can be seen during the lifetime of any semiconductor product include temperature, humidity, electric field, magnetic field, current density, pressure differ- ential, vibration, and/or a chemical interaction. reliability testing is generally formulated to take into account all of these potential factors either individually or in multiple combinations. once the testing has been completed predic- tions can be made for the intended product customer base. if a failure would be detected during reliability testing, the cause of the failure can be categorized into one of the following: design, manufacturing, materials, or user. the possible impact on the improvements that may need to be made for a product is influenced by the stage of product development. if a product undergoes reliability testing early in its development phase, the corrective action process can generally occur in an expedient manner and at minimum cost. this would be true whether the cause of failure was attributed to the design, manufacturing, or materials. if a reliability failure is detected once the product is in full production, changes can be very difficult to make and generally are very costly. this scenario would sometimes result in a total redesign. the potential cause for a reliability failure can also be user induced. this is generally the area that the least information is known, especially for a commodity type manufacturer that achieves sales through a global distribu- tion network. it is the task of the reliability engineer to best anticipate the multitudes of environments that a particular product might see, and determine the robustness of the product by measuring the reliability lifetime parameters. the areas of design, manufacturing, and materials are generally well understood by the reliability engineer, but without the correct environmental usage, customer satis- faction can suffer from lack of optimization. reliability statistics without standardization of the semiconductor sensor stan- dards, the end customer is placed in a situation of possible jeopardy. if non-standard reliability data is generated and published by manufacturers, the information can be perplexing to disseminate and compare. reliability lifetime statistics can be confusing for the novice user of the informa- tion, alet the buyer bewareo. the reporting of reliability statistics is generally in terms of failure rate, measured in fits, or failure rate for one billion device hours. in most cases, the underlying assumption used in reporting either the failure rate or the mtbf is that the failures occurring during the reliability test follow an expo- nential life distribution. the inverse of the failure rate is the mtbf, or mean time between failure. the details on the various life distributions will not be explored here but the key concern about the exponential distribution is that the failure rate over time is constant. other life distributions, such as the lognormal or weibull can take on different failure rates over time, in particular, both distributions can represent a wear out or increasing failure rate that might be seen on a product reaching the limitations on its lifetime or for certain types of failure mechanisms. the time duration use for the prediction of most reliability statistics is of relatively short duration with respect to the product's lifetime ability and failures are usually not observed. when a test is terminated after a set number of hours is achieved, or time censored, and no failures are observed, the failure rate can be estimated by use of the chi- square distribution which relates observed and expected f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
14 motorola sensor device data www.motorola.com/semiconductors frequencies of an event to established confidence intervals. the relationship between failure rate and the chi-square distribution is as follows: l1 2 , d.f. 2t where: l = failure rate l1 = lower one side confidence limit c 2 = chisquare function a = risk, (1confidence level) d.f. = degrees of freedom = 2 (r + 1) r = number of failures t = device hours chi-square values for 60% and 90% confidence intervals for up to 12 failures is shown in table 1. as indicated by the table, when no failures occur, an estimate for the chi-square distribution interval is obtainable. this interval estimate can then be used to solve for the failure rate, as shown in the equation above. if no failures occur, the failure rate estimate is solely a function of the accumulated device hours. this estimate can vary dramati- cally as additional device hours are accumulated. as a means of showing the influence of device hours with no failures on the failure rate value, a graphical representa- tion of cumulative device hours versus the failure rate measured in fits is shown in figure 1. a descriptive example between two potential vendors best serves to demonstrate the point. if vendor a is introducing a new product and they have put a total of 1,000 parts on a high temperature storage test for 500 hours each, their corresponding cumulative device hours would be 500,000 device hours. vendor b has been in the business for several years on the same product and has tested a total of 500,000 parts for 10 hours each to the same conditions as part of an in-line burn-in test for a total of 5,000,000 device hours. the corresponding failure rate for a 60% confidence level for vendor a would be 1,833 fits, vendor b would have a fit rate of 183 fits. table 1. chi-square table chi-square distribution function 60% confidence level 90% confidence level no. fails c 2 quantity no. fails c 2 quantity 0 1.833 0 4.605 1 4.045 1 7.779 2 6.211 2 10.645 3 8.351 3 13.362 4 10.473 4 15.987 5 12.584 5 18.549 6 14.685 6 21.064 7 16.780 7 23.542 8 18.868 8 25.989 9 20.951 9 28.412 10 23.031 10 30.813 11 25.106 11 33.196 12 27.179 12 35.563 cumulative device hours, [t] 10 5 10 8 10 7 10 9 10 4 100 10 1 0.1 1,000 10 6 1 10 100 1,000 10 4 10 5 10 6 10 7 10 8 10 9 failure rate, [fits] figure 1. depiction of the influence on the cumulative device hours with no failures and the failure rate as measured in fits. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
15 motorola sensor device data www.motorola.com/semiconductors one could thus imply that the reliability performance indicates that vendor b has an order of magnitude improve- ment in performance over vendor a with neither one seeing an occurrence of failure during their performance. the incorrect assumption of a constant failure rate over time can potentially result in a less reliable device being designed into an application. the reliability testing assump- tions and test methodology between the various vendors needs to be critiqued to insure a full understanding of the product performance over the intended lifetime, especially in the case of a new product. testing to failure and determina- tion of the lifetime statistics is beyond the scope of this paper and presented elsewhere [2]. industry reliability standards reliability standards for large market segments are often developed by across-corporationo committees that evaluate the requirements for the particular application of interest. it is the role of these committees to generate documents intended as guides for technical personnel of the end users and suppliers, to assist with the following functions: speci- fying, developing, demonstrating, calibrating, and testing the performance characteristics for the specific application. one such committee which has developed a standard for a particular application is the blood pressure monitoring committee of the association for the advancement of medical instrumentation (aami) [3]. their document, the aamerican national standard for interchangeability and performance of resistive bridge type blood pressure transducerso, has an objective to provide performance requirements, test methodology, and terminology that will help insure that safe, accurate blood pressure transducers are supplied to the marketplace. in the automotive arena, the society of automotive engineers (sae) develops standards for various pressure sensor applications such as sae document j1346, aguide to manifold absolute pressure transducer representative test methodo [4]. while these two very distinct groups have successfully developed the requirements for their solid-state silicon pressure sensor needs, no real standard has been set for the general industrial marketplace to insure products being offered have been tested to insure reliability under industrial conditions. motorola has utilized mil-std-750 as a refer- ence document in establishing reliability testing practices for the silicon pressure sensor, but the differences in the technology between a discrete semiconductor and a silicon pressure sensor varies dramatically. the additional tests that are utilized in semiconductor sensor reliability testing are based on the worst case operational conditions that the device might encounter in actual usage. established sensor testing motorola has established semiconductor sensor reliability testing based on exercising to detect failures by the presence of the environmental stress. potential failure modes and causes are developed by allowing tests to run beyond the normal test times, thus stressing to destruction. the typical reliability test matrix used to insure conformance to customers end usage is as follows [5]: pulsed pressure temperature cycling with bias (pptcb) this test is an environmental stress test combined with cyclic pressure loading in which the devices are alternately subjected to a low and high temperature while operating under bias under a cyclical pressure load. this test simulates the extremes in the operational life of a pressure sensor. pptcb evaluates the sensor's overall performance as well as evaluating the die, die bond, wire bond and package integrity. typical test conditions: temperature per specified operating limits (i.e., ta = 40 to 125 c for an automotive application). dwell time 15 minutes, transfer time 5 minutes, bias = 100% rated voltage. pressure = 0 to full scale, pressure frequency = 0.05 hz, test time = up to 1000 hours. potential failure modes: open, short, parametric shift. potential failure mechanisms: die defects, wire bond fatigue, die bond fatigue, port adhesive failure, volumetric gel changes resulting in excessive package stress. mechanical creep of packaging material. high humidity, high temperature with bias (h 3 tb) a combined environmental/electrical stress test in which devices are subjected to an elevated ambient temperature and humidity while under bias. the test is useful for evaluating package integrity as well as detecting surface contamination and processing flaws. typical test conditions: temperature between 60 and 85 c, relative humidity between 85 and 90%, rated voltage, test time = up to 1000 hours. potential failure modes: open, short, parametric shift. potential failure mechanisms: shift from ionic affect, parametric instability, moisture ingress resulting in exces- sive package stress, corrosion. high temperature with bias (htb) this operational test exposes the pressure sensor to a high temperature ambient environment in which the device is biased to the rated voltage. the test is useful for evaluating the integrity of the interfaces on the die and thin film stability. typical test conditions: temperature per specified operational maximum, bias = 100% rated voltage, test time = up to 1000 hours. potential failure modes: parametric shift in offset and/or sensitivity. potential failure mechanisms: bulk die or diffusion defects, film stability and ionic contamination. high and low temperature storage life (htsl, ltsl) high and low temperature storage life testing is performed to simulate the potential shipping and storage conditions that the pressure sensor might encounter in actual usage. the test also evaluates the devices thermal integrity at worst case temperatures. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
16 motorola sensor device data www.motorola.com/semiconductors typical test conditions: temperature per specified storage maximum and minimum, no bias, test time = up to 1000 hours. potential failure modes: parametric shift in offset and/or sensitivity. potential failure mechanisms: bulk die or diffusion defects, mechanical creep in packaging components due to thermal mismatch. temperature cycling (tc) this is an environmental test in which the pressure sensor is alternatively subjected to hot and cold temperature extremes with a short stabilization time at each temperature in an air medium. the test will stress the devices by generating thermal mismatches between materials. typical test conditions: temperature per specified storage maximum and minimum (i.e., 40 to +125 c for automotive applications). dwell time 15 minutes, transfer time 5 minutes, no bias. test time up to 1000 cycles. potential failure modes: open, parametric shift in offset and/or sensitivity. potential failure mechanisms: wire bond fatigue, die bond fatigue, port adhesive failure, volumetric gel changes resulting in excessive package stress. mechanical creep of packaging material. mechanical shock this is an environmental test where the sensor device is evaluated to determine its ability to withstand a sudden change in mechanical stress due to an abrupt change in motion. this test simulates motion that may be seen in handling, shipping or actual use. mil std 750, method 2016 reference. typical test conditions: acceleration = 1500 g's, orienta- tion = x, y, z planes, time = 0.5 milliseconds, 5 blows. potential failure modes: open, parametric shift in offset and/or sensitivity. potential failure mechanisms: diaphragm fracture, mechanical failure of wire bonds or package. variable frequency vibration a test to examine the ability of the pressure sensor device to withstand deterioration due to mechanical resonance. mil std 750, method 2056 reference. typical test conditions: frequency 10 hz to 2 khz, 6.0 g's max, orientation = x, y, z planes, 8 cycles each axis, 2 hrs. per cycle. potential failure modes: open, parametric shift in offset and/or sensitivity. potential failure mechanisms: diaphragm fracture, mechanical failure of wire bonds or package. solderability in this reliability test, the lead/terminals are evaluated for their ability to solder after an extended time period of storage (shelf life). mil std 750, method 2026 reference. typical test conditions: steam aging = 8 hours, flux= r, solder = sn63, pb37. potential failure modes: pin holes, nonwetting, dewetting. potential failure mechanisms: poor plating, contamination. over pressure this test is performed to measure the ability of the pressure sensor to withstand excessive pressures that may be encountered in the application. the test is performed from either the front or back side depending on the application. typical test conditions: pressure increase to failure, record value. potential failure modes: open. potential failure mechanisms: diaphragm fracture, adhesive or cohesive failure of die attach. a pressure sensor may be placed in an application where it will be exposed to various media that may chemically attack the active circuitry, silicon, interconnections and/or packaging material. the focus of media compatibility is to understand the chemical impact with the other environmental factors such as temperature and bias and determine the impact on the device lifetime. the primary driving mecha- nism to consider is permeation which quantifies the time for a chemical to permeate across a membrane or encapsulant corrosion can result. media related product testing is generally very specific to the application since the factors that relate to the product lifetime are very numerous and varied. an example is solution ph where the further from neutral will drive the chemical reaction, generally to a power rule relationship. the ph alone does not always drive the reaction either, the nondesired products in the media such as strong acids in fuels as a result of acid rain can directly influence the lifetime. it is recommended the customer and/or vendor perform application specific testing that best represents the environ- ment. this testing should be performed utilizing in situ monitoring of the critical device parameter to insure the device survives while exposed to the chemical. the sensor products division within motorola has a wide range of media specific test capabilities and under certain circumstances will perform application specific media testing. a sufficient sample size manufactured over a pre-defined time interval to maximize process and time variability is tested based on the guidelines of the matrix shown above. this test methodology is employed on all new product introductions and process changes on current products. a silicon pressure sensor has a typical usage environ- ment of pressure, temperature, and voltage. unlike the typical bipolar transistor life tests which incorporate current density and temperature to accelerate failures, a silicon pressure sensor's acceleration of its lifetime performance is primarily based on the pressure and temperature interac- tion with a presence of bias. this rationale was incorporated into the development of the pulsed pressure temperature cycling with bias (pptcb) test where the major accelera- tion factor is the pressure and temperature component. it is also why pptcb is considered the standard sensor operational life test. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
17 motorola sensor device data www.motorola.com/semiconductors to insure that silicon pressure sensors are designed and manufactured for reliability, an in-depth insight into what mechanisms cause particular failures is required. it is safe to say that unless a manufacturer has a clear understanding of everything that can go wrong with the device, it cannot design a device for the highest reliability. figure 2 provides a look into the sensor operating concerns for a variety of potential usage applications. this information is utilized when developing the failure mode and effects analysis (fmea). the fmea then serves as the documentation that demonstrates all design and process concerns have been addressed to offer the most reliable approach. by under- standing how to design products, control processes, and eliminate the concerns raised, a reliable product is achieved. accelerated life testing it is very difficult to assess the reliability statistics for a product when very few or no failures occur. with cost as a predominant factor in any industrial setting and time of the utmost importance, the reliability test must be optimized. optimization of reliability testing will allow the maximum amount of information on the product being tested to be gained in a minimum amount of time, this is accomplished by using accelerated life testing techniques. a key underlying assumption in the usage of accelerated life testing to estimate the life of a product at a lower or nominal stress is that the failure mechanism encountered at the high stress is the same as that encountered at the nominal stress. the most frequently applied accelerated environmental stress for semiconductors is temperature, it will be briefly explained here for its utilization in deter- mining the lifetime reliability statistics for silicon pressure sensors. package: integrity plating quality dimensions thermal resistance mechanical resistance pressure resistance media compatibility gel: viscosity thermal coefficient of expansion permeability (diffusion x solubility) changes in material or process height coverage uniformity adhesive properties media compatibility gel aeration compressibility die metallization: lifting or peeling alignment scratches voids laser trimming thickness step coverage contact resistance integrity bonding wires: strength placement height and loop size material bimetallic contamination (kirkendall voids) nicking and other damage general quality & workmanship diaphragm: size thickness uniformity pits alignment fracture passivation: thickness mechanical defects integrity uniformity leads: materials and finish plating integrity solderability general quality strength contamination corrosion adhesion electrical performance: continuity and shorts parametric stability parametric performance temperature performance temperature stability long term reliability storage degradation susceptibility to radiation damage design quality die attach: uniformity resistance to mechanical stress resistance to temperature stress wetting adhesive strength cohesive strength process controls die orientation die height change in material or process media compatibility compressibility design changes material or process changes fab & assembly cleanliness surface contamination foreign material scribe defects diffusion defects oxide defects figure 2. process and product variability concerns during reliability testing marking: permanency clarity sensor reliability concerns ?????????? f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
18 motorola sensor device data www.motorola.com/semiconductors the temperature acceleration factor for a particular failure mechanism can be related by taking the ratio for the reaction rate of the two different stress levels as expressed by the arrhenius type of equation. the mathematical derivation of the first order chemical reaction rate computes to: af (r t ) hs t hs (r t ) ls t ls af exp ea k 1 t ls 1 t hs where: af = acceleration factor r t = reaction rate t = time t = temperature [ k] ea = activation energy of expressed in electron-volts [ev] k = boltzman's constant, 8.6171 x 10 -5 ev/ k ls = low stress or nominal temperature hs = high stress or test temperature the activation energy is dependent on the failure mecha- nism and typically varies from 0.3 to 1.8 electron-volts. the activation energy is directly proportional to the degree of influence that temperature has on the chemical reaction rate. a listing of typical activation energies is included in reference [6] and [7]. an example using the arrenhius equation will be demon- strated. a 32 device htb test for 500 hours total and no failure was performed. the 125 c, 100% rated voltage test resulted in no failures. if a customer's actual usage conditions was 55 c at full rated voltage, an estimate of the lower one side confidence limit can be calculated. an assumption is made that the failure rate is constant thus implying the exponential distribution. the first step is to calculate the equivalent device hours for the customer's use conditions by solving for the acceleration factor. from the acceleration factor above, if ea is assumed equal to 1, af exp ea k 1 t ls 1 t hs where: ea = 0.7ev/ k (assumed) t ls =55 c + 273.16 = 328.16 k t hs = 125 c + 273.16 = 398.16 k then; af = 77.64 therefore, the equivalent cumulative device hours at the customer's use condition is: t ls = af x t hs = (32 500) 77.64 or t ls = 1,242,172 device hours computing the lower one sided failure rate with a 90% confi- dence level and no failures: 2 ( , d.f. ) 2t or l = 1.853e06 failures per hour or l = 1,853 fits the inverse of the failure, l , or the mean time to failure (mttf) is: mttf 1 or mttf = 540,000 device hours conclusion reliability testing durations and acceptance numbers are used as a baseline for achieving adequate performance in the actual use condition that the silicon pressure sensor might encounter. the baseline for reliability testing can be related to the current record high jump bar height. just as athletes in time achieve a higher level of performance by improvements in their level of physical and mental fitness, silicon pressure sensors must also incorporate improve- ments in the design, materials, and manufacturability to achieve the reliability growth demands the future market place will require. this philosophy of never ending improve- ment will promote consistent conformance to the customer's expectation and production of a best in class product. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
19 motorola sensor device data www.motorola.com/semiconductors references [1] dr. joseph e. matar and theresa maudie, areliability engineering and accelerated life testing,o motorola internal training text, 1989. [2] d.j. monk, t. maudie, d. stanerson, j. wertz, g. bitko, j. matkin, and s. petrovic, amedia compatible packaging and environmental testing of barrier coating encapsulated silicon pressure sensors,'' 1996, solidstate sensors and actuators workshop. hilton head, sc, pp. 3641, 1996. [3] aguide to manifold absolute pressure transducer representative test method,o sae guideline j1346, transducer subcommittee, latest revision. [4] ainterchangeability and performance of resistive bridge type blood pressure transducers,o aami guideline, blood pressure monitoring committee, latest revision. [5] amotorola d.m.t.g. reliability audit report,o q191. [6] wayne nelson, aaccelerated testing: statistical models,o test plans, and data analyses, john wiley & sons, inc., new york, n.y., 1990. [7] d.s. peck and o.d. trapp, (1978), aaccelerated testing handbook,o technology associates, revised 1987. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
110 motorola sensor device data www.motorola.com/semiconductors soldering precautions the melting temperature of solder is higher than the rated temperature of the device. when the entire device is heated to a high temperature, failure to complete soldering within a short time could result in device failure. therefore, the following items should always be observed in order to mini- mize the thermal stress to which the devices are subjected. ? always preheat the device. ? the delta temperature between the preheat and soldering should be 100 c or less.* ? for pressure sensor devices, a noclean solder is recommended unless the silicone die coat is sealed and unexposed. also, prolonged exposure to fumes can damage the silicone die coat of the device during the solder reflow process. ? when preheating and soldering, the temperature of the leads and the case must not exceed the maximum temperature ratings as shown on the data sheet. when using infrared heating with the reflow soldering method, the difference should be a maximum of 10 c. ? the soldering temperature and time should not exceed 260 c for more than 10 seconds. ? when shifting from preheating to soldering, the maximum temperature gradient shall be 5 c or less. ? after soldering has been completed, the device should be allowed to cool naturally for at least three minutes. gradual cooling should be used since the use of forced cooling will increase the temperature gradient and will result in latent failure due to mechanical stress. ? mechanical stress or shock should not be applied during cooling. * soldering a device without preheating can cause excessive thermal shock and stress which can result in damage to the device. typical solder heating profile for any given circuit board, there will be a group of control settings that will give the desired heat pattern. the operator must set temperatures for several heating zones and a figure for belt speed. taken together, these control settings make up a heating aprofileo for that particular circuit board. on machines controlled by a computer, the computer remem- bers these profiles from one operating session to the next. figure 3 shows a typical heating profile for use when soldering a surface mount device to a printed circuit board. this profile will vary among soldering systems, but it is a good starting point. factors that can affect the profile include the type of soldering system in use, density and types of components on the board, type of solder used, and the type of board or substrate material being used. this profile shows temperature versus time. the line on the graph shows the actual temperature that might be experienced on the surface of a test board at or near a central solder joint. the two profiles are based on a high density and a low density board. the vitronics smd310 convection/infrared reflow soldering system was used to generate this profile. the type of solder used was 62/36/2 tin lead silver with a melting point between 177 189 c. when this type of furnace is used for solder reflow work, the circuit boards and solder joints tend to heat first. the components on the board are then heated by conduction. the circuit board, because it has a large surface area, absorbs the thermal energy more efficiently, then distributes this energy to the components. because of this effect, the main body of a component may be up to 30 degrees cooler than the adjacent solder joints. step 1 preheat zone 1 arampo step 2 vent asoako step 3 heating zones 2 & 5 arampo step 4 heating zones 3 & 6 asoako step 5 heating zones 4 & 7 aspikeo step 6 vent step 7 cooling 200 c 150 c 100 c 50 c time (3 to 7 minutes total) t max solder is liquid for 40 to 80 seconds (depending on mass of assembly) 205 to 219 c peak at solder joint desired curve for low mass assemblies 100 c 150 c 160 c 170 c 140 c figure 3. typical solder heating profile desired curve for high mass assemblies f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
111 motorola sensor device data www.motorola.com/semiconductors electrostatic discharge data electrostatic damage (esd) to semiconductor devices has plagued the industry for years. special packaging and handling techniques have been developed to protect these sensitive devices. while many of motorola's semiconductors devices are not susceptible to esd, all products are revered as sensitive and handled accordingly. the data in this section was developed using the human-body model specified in mil-std-750c, method 1020. the threshold values (eth, kv) of ten devices was recorded, then the average value calculated. this data plus the device type, device source, package type, classification, polarity and general device description are supplied. devices listed are mainly jedec registered 1n and 2n numbers. military qpl devices and some customer specials are also in this database. the data in this report will be updated regularly, and the range will be added as new data becomes available. the sensitivity classifications listed are as follows: class 1 . . .1 to 1999 volts class 2 . . .2000 to 3999 volts class 3 . . .4000 to > 15500 volts the code an/so signifies a non-sensitive device. aseno are considered sensitive and should be handled according to esd procedures. of the various products manufactured by the communications, power and signal technologies group, the following examples list general device families by not sensitive to extremely sensitive. not sensitive fet current regulators . . . . . . least sensitive zener diodes (on a square . . . . mil/millijoule basis) less sensitive bipolar transistors . . . . . more sensitive bipolar darlington transistors . . . . very sensitive power tmos ? devices . . . . . extremely sensitive hot carrier diodes and mosfet transistors without gate protection the data supplied herein, is listed in numerical or alphabetical order. device line case class product description mpx10d xl0010v1 34415 3sen uncompensated mpx10dp xl0010v1 344c01 3sen uncompensated mpx10gp xl0010v1 344b01 3sen uncompensated mpx12d xl0012v1 34415 3sen uncompensated mpx12dp xl0012v1 344c01 3sen uncompensated mpx12gp xl0012v1 344b01 3sen uncompensated mpx2010d xl2010v5 34415 1sen temperature compensated/calibrated mpx2010dp xl2010v5 344c01 1sen temperature compensated/calibrated mpx2010gp xl2010v5 344b01 1sen temperature compensated/calibrated mpx2010gs xl2010v5 344e01 1sen temperature compensated/calibrated mpx2010gsx xl2010v5 344f01 1sen temperature compensated/calibrated mpx2300dt1 xl2300c1,01c1 42305 1sen temperature compensated/calibrated mpx4100a xl4101s2 86708 1sen signalconditioned mpx4100ap xl4101s2 867b04 1sen signalconditioned mpx4100as xl4101s2 867e03 1sen signalconditioned mpx4101a xl4101s2 86708 1sen signalconditioned mpx4115a xl4101s2 86708 1sen signalconditioned mpx4115ap xl4101s2 867b04 1sen signalconditioned mpx4115as xl4101s2 867e03 1sen signalconditioned mpx4250a xl4101s2 86708 1sen signalconditioned mpx4250ap xl4101s2 867b04 1sen signalconditioned mpx5010d xl4010s5 86708 1sen signalconditioned mpx5010dp xl4010s5 867c05 1sen signalconditioned mpx5010gp xl4010s5 867b04 1sen signalconditioned mpx5010gs xl4010s5 867e03 1sen signalconditioned mpx5010gsx xl4010s5 867f03 1sen signalconditioned f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
112 motorola sensor device data www.motorola.com/semiconductors device product description class case line mpx5050d xl4051s1 86708 1sen signalconditioned mpx5050dp xl4051s1 867c05 1sen signalconditioned mpx5050gp xl4051s1 867b04 1sen signalconditioned mpx5100d xl4101s1 86708 1sen signalconditioned mpx5100dp xl4101s1 867c05 1sen signalconditioned mpx5100gp xl4101s1 867b04 1sen signalconditioned mpx5700d xl4701s1 86708 1sen signalconditioned mpx5700dp xl4701s1 867c05 1sen signalconditioned mpx5700gp xl4701s1 867b04 1sen signalconditioned mpx5999d xl4999s1 86708 1sen signalconditioned f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
113 motorola sensor device data www.motorola.com/semiconductors statistical process control motorola's semiconductor products sector is continually pursuing new ways to improve product quality. initial design improvement is one method that can be used to produce a superior product. equally important to outgoing product quality is the ability to produce product that consistently conforms to specification. process variability is the basic enemy of semiconductor manufacturing since it leads to product variability. used in all phases of motorola's product manufacturing, statistical process control (spc) replaces variability with predictability. the traditional philos- ophy in the semiconductor industry has been adherence to the data sheet specification. using spc methods assures the product will meet specific process requirements throughout the manufacturing cycle. the emphasis is on defect prevention, not detection. predictability through spc methods requires the manufacturing culture to focus on constant and permanent improvements. usually these improvements cannot be bought with state-of-the-art equip- ment or automated factories. with quality in design, process and material selection, coupled with manufacturing predict- ability, motorola produces world class products. the immediate effect of spc manufacturing is predict- ability through process controls. product centered and distributed well within the product specification benefits motorola with fewer rejects, improved yields and lower cost. the direct benefit to motorola's customers includes better incoming quality levels, less inspection time and ship-to- stock capability. circuit performance is often dependent on the cumulative effect of component variability. tightly controlled component distributions give the customer greater circuit predictability. many customers are also converting to just-in-time (jit) delivery programs. these programs require improvements in cycle time and yield predictability achiev- able only through spc techniques. the benefit derived from spc helps the manufacturer meet the customer's expecta- tions of higher quality and lower cost product. ultimately, motorola will have six sigma capability on all products. this means parametric distributions will be centered within the specification limits with a product distribution of plus or minus six sigma about mean. six sigma capability, shown graphically in figure 1, details the benefit in terms of yield and outgoing quality levels. this compares a centered distribution versus a 1.5 sigma worst case distribution shift. new product development at motorola requires more robust design features that make them less sensitive to minor variations in processing. these features make the implementation of spc much easier. a complete commitment to spc is present throughout motorola. all managers, engineers, production operators, supervisors and maintenance personnel have received multiple training courses on spc techniques. manufac- turing has identified 22 wafer processing and 8 assembly steps considered critical to the processing of semiconductor products. processes, controlled by spc methods, that have shown significant improvement are in the diffusion, photoli- thography and metallization areas. figure 1. aoql and yield from a normal distribution of product with 6 s capability standard deviations from mean distribution centered distribution shifted 1.5 at 3 s 2700 ppm defective 99.73% yield at 4 s 63 ppm defective 99.9937% yield at 5 s 0.57 ppm defective 99.999943% yield at 6 s 0.002 ppm defective 99.9999998% yield 66810 ppm defective 93.32% yield 6210 ppm defective 99.379% yield 233 ppm defective 99.9767% yield 3.4 ppm defective 99.99966% yield -6 s -5 s -4 s -3 s -2 s -1 s 0 1 s 2 s 3 s 4 s 5 s 6 s to better understand spc principles, brief explanations have been provided. these cover process capability, imple- mentation and use. process capability one goal of spc is to ensure a process is capable . process capability is the measurement of a process to produce products consistently to specification requirements. the purpose of a process capability study is to separate the inherent random variability from assignable causes . once completed, steps are taken to identify and eliminate the most significant assignable causes. random variability is generally present in the system and does not fluctuate. sometimes, these are considered basic limitations associated with the machinery, materials, personnel skills or manufacturing methods. assignable cause inconsistencies relate to time variations in yield, performance or reliability. traditionally, assignable causes appear to be random due to the lack of close examination or analysis. figure 2 shows the impact on predictability that assignable cause can have. figure 3 shows the difference between process control and process capability. a process capability study involves taking periodic samples from the process under controlled conditions. the performance characteristics of these samples are charted against time. in time, assignable causes can be identified and engineered out. careful documentation of the process is key to accurate diagnosis and successful removal of the assignable causes. sometimes, the assignable causes will remain unclear requiring prolonged experimentation. elements which measure process variation control and capability are cp and cpk respectively. cp is the specification width divided by the process width or cp = (specification width) / 6 s. cpk is the absolute value of the closest specification value to the mean, minus the mean, divided by half the process width or cpk = | closest specification x /3 s . f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
114 motorola sensor device data www.motorola.com/semiconductors figure 2. impact of assignable causes on process predictable figure 3. difference between process control and process capability ? ? ? ? ? ? ? ? ? process aunder controlo all assignable causes are removed and future distribution is predictable. prediction time size size time prediction size time out of control (assignable causes present) in control assignable causes eliminated size time in control but not capable (variation from random variability excessive) lower specification limit upper specification limit in control and capable (variation from random variability reduced) ? ? at motorola, for critical parameters, the process capability is acceptable with a cpk = 1.33. the desired process capability is a cpk = 2 and the ideal is a cpk = 5. cpk, by definition, shows where the current production process fits with relationship to the specification limits. off center distributions or excessive process variability will result in less than optimum conditions spc implementation and use dmtg uses many parameters that show conformance to specification. some parameters are sensitive to process variations while others remain constant for a given product line. often, specific parameters are influenced when changes to other parameters occur. it is both impractical and unnecessary to monitor all parameters using spc methods. only critical parameters that are sensitive to process variability are chosen for spc monitoring. the process steps affecting these critical parameters must be identified also. it is equally important to find a measurement in these process steps that correlates with product performance. this is called a critical process parameter. once the critical process parameters are selected, a sample plan must be determined. the samples used for measurement are organized into rational subgroups of approximately 2 to 5 pieces. the subgroup size should be such that variation among the samples within the subgroup remain small. all samples must come from the same source e.g., the same mold press operator, etc.. subgroup data should be collected at appropriate time intervals to detect variations in the process. as the process begins to show improved stability, the interval may be increased. the data collected must be carefully documented and maintained for later correlation. examples of common documentation entries would include operator, machine, time, settings, product type, etc. once the plan is established, data collection may begin. the data collected will generate x and r values that are plotted with respect to time. x refers to the mean of the values within a given subgroup, while r is the range or greatest value minus least value. when approximately 20 or more x and r values have been generated, the average of these values is computed as follows: x x x x = ( + 2 +3 + ...)/k r = (r1 + r2 + r3 + ...)/k where k = the number of subgroups measured. the values of x and r are used to create the process control chart. control charts are the primary spc tool used to signal a problem. shown in figure 4, process control charts show x and r values with respect to time and concerning reference to upper and lower control limit values. control limits are computed as follows: r upper control limit ucl r d4 r r lower control limit lcl r d3 r x upper control limit ucl x x a2 r x lower control limit lcl x x a2 r f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
115 motorola sensor device data www.motorola.com/semiconductors figure 4. example of process control chart showing oven temperature data 147 148 149 150 151 152 153 154 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 0 1 2 3 4 5 6 7 ucl = 152.8 = 150.4 lcl = 148.0 ucl = 7.3 = 3.2 lcl = 0 x r where d4, d3 and a2 are constants varying by sample size,with values for sample sizes from 2 to 10 shown in the following partial table: n2345678910 d 4 3.27 2.57 2.28 2.11 2.00 1.92 1.86 1.82 1.78 d 3 * * * * * 0.08 0.14 0.18 0.22 a 2 1.88 1.02 0.73 0.58 0.48 0.42 0.37 0.34 0.31 * for sample sizes below 7, the lcl r would technically be a negative number; in those cases there is no lower control limit; this means that for a subgroup size 6, six aidenticalo measurements would not be unreasonable. control charts are used to monitor the variability of critical process parameters. the r chart shows basic problems with piece to piece variability related to the process. the x chart can often identify changes in people, machines, methods, etc. the source of the variability can be difficult to find and may require experimental design techniques to identify assignable causes. some general rules have been established to help deter- mine when a process is out-of-control . figure 5 shows a control chart subdivided into zones a, b, and c corre- sponding to 3 sigma, 2 sigma, and 1 sigma limits respectively. in figure 6 through figure 9 four of the tests that can be used to identify excessive variability and the presence of assignable causes are shown. as familiarity with a given process increases, more subtle tests may be employed successfully. once the variability is identified, the cause of the variability must be determined. normally, only a few factors have a signif- icant impact on the total variability of the process. the impor- tance of correctly identifying these factors is stressed in the following example. suppose a process variability depends on the variance of five factors a, b, c, d and e. each has a vari- ance of 5, 3, 2, 1 and 0.4 respectively. since: tot a 2 b 2 c 2 d 2 e 2 tot 5 2 3 2 2 2 1 2 ( 0.4 ) 2 6.3 now if only d is identified and eliminated then; tot 5 2 3 2 2 2 ( 0.4 ) 2 6.2 this results in less than 2% total variability improvement. if b, c and d were eliminated, then; tot 5 2 ( 0.4 ) 2 5.02 this gives a considerably better improvement of 23%. if only a is identified and reduced from 5 to 2, then; tot 2 2 3 2 2 2 1 2 ( 0.4 ) 2 4.3 identifying and improving the variability from 5 to 2 gives us a total variability improvement of nearly 40%. most techniques may be employed to identify the primary assignable cause(s). out-of-control conditions may be correlated to documented process changes. the product may be analyzed in detail using best versus worst part comparisons or product analysis lab equipment. multi-vari- ance analysis can be used to determine the family of varia- tion (positional, critical or temporal). lastly, experiments may be run to test theoretical or factorial analysis. whatever method is used, assignable causes must be identified and eliminated in the most expeditious manner possible. after assignable causes have been eliminated, new control limits are calculated to provide a more challenging variability criteria for the process. as yields and variability improve, it may become more difficult to detect improve- ments because they become much smaller. when all assignable causes have been eliminated and the points remain within control limits for 25 groups, the process is said to be in a state of control. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
116 motorola sensor device data www.motorola.com/semiconductors ucl lcl ucl ucl ucl ucl lcl lcl lcl lcl centerline a b c c b a a b c c b a a b c c b a a b c c b a zone a (+ 3 sigma) zone b (+ 2 sigma) zone c (+ 1 sigma) zone c ( 1 sigma) zone b ( 2 sigma) zone a ( 3 sigma) figure 5. control chart zones figure 6. one point outside control limit indicating excessive variability figure 7. two out of three points in zone a or beyond indicating excessive variability figure 8. four out of five points in zone b or beyond indicating excessive variability figure 9. seven out of eight points in zone c or beyond indicating excessive variability summary motorola's commitment to statistical process controls has resulted in many significant improvements to processes. continued dedication to the spc culture will allow motorola to reach beyond six sigma and zero defect capability goals. spc will further enhance the commitment to total customer satisfaction . f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
117 motorola sensor device data www.motorola.com/semiconductors micromachined accelerometer reliability testing results life and environmental testing results stress test conditions results failed/pass high temperature bias t a = 90 c, v dd = 5.0 v t = 1000 hours, 12 minutes on, 8 seconds off 0/32 high temperature/high humidity bias t a = 85 c, r h = 85%, v dd = 5.0 v, t = 2016 0/38 high temperature storage (bake) t a = 105 c, t = 1000 hours 0/35 temperature cycle 40 to 105 c, air to air, 15 minutes at extremes, 5 minutes transfer, 1000 cycles 0/23 mechanical shock 5 blows x1, x2, y1, y2, z1, z2 2.0 g's, 0.5 ms, t a = 40 c, 25 c, 90 c 0/12 vibration variable frequency with temperature cycle 10 1 khz @ 50 g's max, 24 hours each axis, x1, x2, y1, y2, z1, z2, t a = 40 to 90 c, dwell = 1 hour, transfer = 65 minutes 0/12 autoclave t a = 121 c, r h = 100% 15 p sig , t = 240 hours 0/71 drop test 10 drops from 1.0 meters onto concrete, any orientation 0/12 parameters monitored limits initial end points parameter conditions min max min max offset v dd = 5.0 v, 25, 40 & 90 c 2.15 v 2.95 v 2.15 v 2.95v self test v dd = 5.0 v, 25, 40 & 90 c 20g 30 g 20 g 30 g sensitivity v dd = 5.0 v, 25, 40 & 90 c 45 mv/g 55 mv/g 45 mv/g 55 mv/g f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
118 motorola sensor device data www.motorola.com/semiconductors media compatibility disclaimer motorola has tested media tolerant sensor devices in selected solutions or environments and test results are based on particular conditions and procedures selected by motorola. customers are advised that the results may vary for actual services conditions. customers are cautioned that they are responsible to determine the media compatibility of sensor devices in their applications and the foreseeable use and misuses of their applications. sensor media compatibility: issues and answers t. maudie, d. j. monk, d. zehrbach, and d. stanerson motorola semiconductor products sector, sensor products division 5005 e. mcdowell rd., phoenix, az 85018 abstract as sensors and actuators are embedded deeper into electronic systems, the issue of media compatibility as well as sensor and actuator performance and survivability becomes increasingly critical. with a large number of definitions and even more explanations of what media compatibility is, there is a ground swell of confusion not only within the industry, but among end users as well. the sensor industry must respond to create a clear definition of what media compatibility is, then strive to provide a comprehensive understanding and industry wide agreement on what is involved in assessing media tolerance and compatibility. finally, the industry must create a standard set of engineering parameters to design, evaluate, test, and ultimately qualify sensor and actuators functioning in various media conditions. this paper defines media compatibility, identifies pertinent compatibility issues, and recommends a path to industry standardization. introduction microelectromechanical system (mems) reliability in various media is a subject that has not yet received much attention in the literature yet [13], but does bring up many potential issues. the effects of long term media exposure to the silicon mems device and material still need answers [4]. testing can result in predictable silicon or package related failures, but due to the complexity of the mechanisms, deleterious failures can be observed. the sensor may be exposed to diverse media in markets such as automotive, industrial, and medical. this media may include polar or nonpolar organic liquids, acids, bases, or aqueous solutions. integrated circuits (ics) have long been exposed to temperature extremes, humid environments, and mechanical tests to demonstrate or predict the reliability of the device for the application. unlike a typical ic, a sensor often must exist in direct contact with a harsh environment. the lack of harsh media simulation test standardization for these direct contact situations necessitates development of methods and hardware to perform reliability tests. this paper was presented at sensors expo, anaheim, ca, and is reprinted with permission, sensors magazine (174 concord st., peterborough, nh 03458) and expocon management associates, inc. (p.o. box 915, fairfield, ct 06430). the applicability of media compatibility affects all sensors to some degree, but perhaps none more dramatically than a piezoresistive pressure sensor. in order to provide an accurate, linear output with applied pressure, the media should come in direct contact with the silicon die. any barrier provided between the die and the media, limits the device performance. a typical piezoresistive diaphragm pressure sensor manufactured using bulk micromachining techniques is shown in figure 1. a definition for a media compatible pressure sensor will be proposed. to ensure accurate media testing, the requirements and methods need to be understood, as well as what constitutes a failure. an understanding of the physics of failure can significantly reduce the development cycle time and produce a higher quality product [5,6]. the focus of the physicsoffailure approach includes the failure mechanism, accelerating environment, and failure mode. the requirement for a typical pressure sensor application involves long term exposure to a variety of media at an elevated temperature and may include additional acceleration components such as static or cyclic temperature and pressure. figure 1. typical bulk micromachined silicon piezoresistive pressure sensor device and package configuration. die rtv die bond etched metallization epoxy wire silicon diffused diaphragm lead strain gauge interconnect frame case cavity wafer f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
119 motorola sensor device data www.motorola.com/semiconductors the failure mechanisms that may affect a sensor or actuator will be discussed along with the contributors and acceleration means. failure mechanisms of interest during media testing of semiconductor mems devices are shown in table 1. mems applications may involve disposable applications such as a blood pressure monitor whose lifetime is several days. general attributes to consider during testing include: lifetime expectations, cost target, quality level, size, form, and functionality. table 1. typical failure mechanisms for sensors and actuators [610] failure mechanism uniform corrosion localized corrosion galvanic corrosion silicon etching polymer swelling or dissolution interfacial permeability adhesive strength fatigue crack initiation fatigue crack propagation environment assisted cracking creep methods for performing media compatibility testing to determine the potential for the various failure mechanisms will be presented. attributes of the testing need to be well understood so that proper assessment of failure and lifetime approximation can be made. the lifetime modeling is key for determination of the ability of a sensor device to perform its intended function. reliability modeling and determination of activation energies for the models will provide the customer with an understanding of the device performance. the definition of an electrical failure can range from catastrophic, to exceeding a predetermined limit, to just a small shift. the traditional pre to post electrical characterization (before and after the test interval) can be enhanced by in situ monitoring. in situ monitoring may expose a problem with a mems device during testing that might have gone undetected once the media or another environmental factor is removed. this is a common occurrence for a failure mechanism, such as swelling, that may result in a shift in the output voltage of the sensor. response variables during environmental testing can include: electrical, visual, analytical, or physical characteristics such as swelling or weight change. definitions & underlying causes the definition of a media compatible pressure sensor is as follows: the ability of a pressure sensor to perform its specified electromechanical function over an intended lifetime in the chemical, electrical, mechanical, and thermal environments encountered in a customer's application. the key elements of the definition are perform, function, lifetime, environment, and application. all of these elements are critical to meet the media compatibility needs. the underlying causes of poor media compatibility is the hostile environment and permeability of the environment. the environment may consist of media or moisture with ionics, organics, and/or aqueous solutions, extreme temperatures, voltage, and stress. permeability is the product of diffusivity and solubility. contributors to permeability include materials (e.g. polymeric structures), geometry, processing, and whether or not the penetration is in the bulk or at an interface. the environment can also accelerate permeation if a concentration gradient, elevated temperature and/or pressure exist. an example of material dependence of permeation is shown in figure 2. organic materials such as silicone can permeate 50% of the relative moisture from the exterior within minutes where inorganic materials such as glass takes years for the same process to occur. figure 2. permeation relationship for various materials. min hr day mo yr 10 100 yr yr 5 4 3 2 1 6 silicones fluorocarbons 10 6 10 8 10 10 10 12 10 14 10 16 log thickness (m) p ermeab i l i ty ( g /c ms t orr ) time for package interior to reach 50% of exterior humidity * metals epoxies glasses * richard k. traeger, anonhermiticity of polymeric lid sealants, ieee transactions on parts, hybrids, and packaging, vol. php13, no. 2, june 1977. gasoline and aqueous alkaline solutions represent two relatively diverse applications that are intended for use with a micromachined pressure sensor. the typical automotive temperature range is from 40 to 150 c. this not only makes material selection more difficult but also complicates the associated hardware to perform the media related testing [11]. a typical aqueous alkaline solution application would be found in the appliance industry. this industry typically has a narrower temperature extreme then the automotive market, but the solutions and the level of ions provide a particular challenge to mems device reliability. gasoline contains additives such as: antiknock, antipreignition agents, dyes, antioxidants, metal deactivators, corrosion inhibitors, antiicers, injector or carburetor detergents, and intake valve deposit control additives [12] . to develop a common test scheme for the liquid, a mixture table was developed for material testing in gasoline/methanol mixtures. the gasoline/methanol mixtures developed were intended for accelerated material testing with a gasoline surrogate of astm fuel reference aco (50% toluene and 50% isooctane) [13]. material testing is performed with samples either immersed in the liquid or exposed to the vapor over the liquid. the highly aromatic fuel f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
120 motorola sensor device data www.motorola.com/semiconductors aco is intended to swell polymeric materials. contaminants in actual gasoline can result in corrosion or material degradation, so chloride ions or formic acid with distilled water are added to create an aggressive fuel media. gasoline can decompose by a process called autooxidation that will form aggressive substances that can dissolve polymers or corrode metal. copper is added as a trace metal to accelerate the formation of free radicals from the hydroperoxides. table 2 details the various gasoline/methanol mixtures with additives rec ommended by the task force from chrysler, ford, and general motors. table 2. fuel testing methods elastomer polymer metal alcohol/fuel blends cmo cmo cm15 cm15 cm15 cm30 cm30 cm50 cm50 cm85 cm85 cm85 aggressive fuel, add chloride ion distilled water formic acid chloride ion sodium chloride formic acid auto oxidized fuels, add tbutyl hydroperoxide tbutyl hydroperoxide cu + recommended gasoline/methanol mixtures for material testing. the recommended testing for metals should include immersion in th e liquid as well as exposure to the vapor. the coding for the alcohol/fuel blends, cmxx is: c for fuel c; m for methanol; and xx indicating the percentage of methanol in the mixture. the general question for the appliance industry compatibility issues is not whether the media will contain ions (as it most assuredly will) but at what concentration. tap water with no alkali additives contains ions capable of contributing to a corrosive reaction [14]. a typical application of a pressure sensor in the appliance industry is sensing the water level in a washing machine. the primary ingredients of detergent used in a washing machine are: surfactants, builders, whitening agents and enzymes [15]. the surfactants dissolve dirt and emulsify oil, grease and dirt. they can be anionic or cationic. cationic surfactants are present in detergentsoftener combinations. builders or alkaline water conditioning agents are added to the detergent to soften the water, thus increasing the efficiency of the surfactant. these builders maintain alkalinity that results in improved cleaning. alkaline solutions at temperatures indicated by the appliance industry range can etch bare silicon similar to the bulk micromachining process. thus bare silicon could be adversely affected by exposure to these liquids [16]. failure mechanisms the failure mechanisms that can affect sensors and actuators are similar to that for electronic devices. these failure mechanisms provide a means of categorizing the various effects caused by chemical, mechanical, electrical, and thermal environments encountered. an understanding of the potential failure mechanisms should be determined before media testing begins. the typical industry scenario has been to follow a set boiler plate of tests and then determine reliability. this may have been acceptable for typical electronic devices, but the applications for sensors are more demanding of a thorough understanding before testing begins. the sensitivity of the device to its physical environment is heightened for a pressure sensor. any change in the material properties results in a change of the sensor performance. failure mechanisms for pressure sensors in harsh media application are listed below. the pressure sensor allows a format for discussion, though the mechanisms discussed are applicable in some degree to all sensor and actuator devices. corrosion corrosion has been defined as any destructive result of a chemical reaction between a metal or metal alloy and its environment [17]. several metal surfaces exist within a pressure sensor package: metallic lines on the die, trimmable resistors, bonding pads, wires, leadframes, etc. much of the dielevel metal is protected by an overlying inorganic passivation material (e.g., pecvd silicon nitride); however, unless some packagelevel encapsulant is used, bondpads, wires, and leadframes are exposed to the harsh media and are potential corrosion sites. furthermore, an energized pressure sensor has a voltage difference between these exposed metallic surfaces, which compounds the corrosion problem. generally, corrosion problems are organized into the following categories: uniform corrosion; galvanic corrosion, and localized corrosion (including, crevice corrosion, pitting corrosion, etc.) [17]. the factors that contribute to corrosion are: the substrate (metallic) material and its surface structure and composition; the influence of a barrier coating, its processing conditions and/or adhesion promotion; the cleanliness of the surface, adhesion between a coating and the surface, solution concentration, solution components (especially impurities and/or oxidizers); localized geometry and applied potential. in addition, galvanic corrosion is influenced by specific metaltometal connections. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
121 motorola sensor device data www.motorola.com/semiconductors figure 3. examples of uniform corrosion of a gold leadframe in nitric acid at 5 vdc and galvanic corrosion on an unbiased device at the gold wire/aluminum bondpad interface in commercial detergent. piezoresistive transducer diaphragm silicon die unibody package die attach lead frame wirebond nitric part of figure 3 shows an example of what we have described as electrolytic corrosion (i.e., corrosion of similar metallic surfaces in an electrolytic solution caused by a sufficient difference in potential between the two surfaces). this appears to be uniform corrosion of the gold leadframe surface. it should be noted that this type of failure is observed even on `noble' metals like gold. applied potential is the driving force for the reaction. all metals can corrode in this fashion depending on the solution concentration (ph) and the applied potential. pourbaix diagrams describe these thermodynamic relationships [18]. figure 3 shows an example of galvanic corrosion. the figure illustrates that corrosion can also occur because of dissimilar metals that are connected electrically and are immersed in an electrolytic solutions. a difference in the corrosion potential between the two metals is the driving force for the reaction. localized corrosion examples are prevalent as well. often they may be the precursor to what appears on a macro scale to be uniform or galvanic corrosion. in situ monitoring of devices in electrolytic media will allow better diagnosis of this failure mechanism. typical ex situ or interval reliability testing may not allow diagnosis of the root cause to the failure, thus limiting the predictive power of any resulting reliability models. silicon etching figure 4 shows the result of an accelerated test of a pressure sensor die to a high temperature detergent solution. the detergent used was a major consumer brand and resulted in dramatic etching of the silicon. alkaline solutions that undergo a hydrolysis reaction may result in etching of the silicon similar to a bulk micromaching operation. this failure mechanism can cause a permanent change in the sensitivity of the device because the sensitivity is proportional to the inverse square of the silicon thickness. moreover, it can lead to loss in bond integrity between wafers (fig. 4). silicon etching [1920], like corrosion reactions, is a chemical reaction, so the contributing factors include the silicon material, its crystal orientation and its doping level, the solution type, concentration and ph, and the applied potential. temperature, concentration (i.e., ph), and voltage all act to accelerate this process. figure 5 shows an example of modeling results that illustrates two of these variables. figure 4. photograph of silicon etching after exposure to an aqueous detergent solution at elevated temperature for an extended time. a frit layer, horizontally in the middle, adheres to silicon on either side. the amount of etching is evident by referencing the glass frit edge on the far left. these two silicon edges were aligned to the frit edge when the die was sawn. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
122 motorola sensor device data www.motorola.com/semiconductors figure 5. experimental results for the etc hing of (100) silicon with approximately 5x10 5 cm 3 boron doping density in a commercially available detergent as a function of temperature and detergent concentration (which is proportional to ph). etch rate <= 0.10 <= 0.20 <= 0.30 prediction <= 0.40 > 0.40 from model 10 temp (c) 0 60 70 80 90 100 110 120 20 30 40 50 contour plot of detergent concentraion and temperature vs etch rate ( m/hr) ultra tide conc (g/l) polymer swelling or dissolution swelling or dissolution affects those polymers typically employed to package the micromachined structure and depending on the nature of the media, may have a degrading effect on device performance. these two related phenomena are caused by solvent diffusing into the material and occupying free volume within the polymer. the solubility parameter gives a quantitative measure of the potential for swelling [21]: i.e., it provides a quantitative measure of alike dissolves likeo (fig. 6). both the polymer and the solution contribute to this failure mechanism, while the media (specifically, the solubility parameter), the temperature, and the pressure can be used as acceleration factors. figure 6. typical values of solubility parameter ( d [cal/cm 3 ] 1/2 ) for solvents and polymers. isooctane toluene ethanol methanol water 22.5 20 17.5 15 12.5 10 7.5 solvents polysulfone polyurethane pet nylon poly (acrylonitrile) polymers ptfe pmma d = [cal/cm 3 ] 1/2 figure 7 shows a photograph of a device after exposure to a harsh fuel containing corrosive water solution. this corrosion and evidence of swelling of the gel demonstrates the vital importance the package has on the reliability of the pressure sensor device. also, it has been observed that corrosion occurs more readily following swelling of a polymeric encapsulant. figure 7. photograph of a pressure sensor device after extended exposure to harsh fuel containing corrosive water, followed by exposure to a strong acid. evidence of the gel swelling during the test, and corresponding shrinkage after removal from the test media can be seen by the gel retracting away from the sidewall of the package. initial edge of gel gel edge after exposure to gasoline with ethanol f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
123 motorola sensor device data www.motorola.com/semiconductors interfacial permeability lead leakage is a specific example of interfacial permeability. it is pressure leakage through the polymer housing material/metallic leadframe material interface from the inside of the pressure sensor package to the outside of the pressure sensor package or vice versa [22]. in addition, other material interfaces can result in leakage. we describe another specific example of this in the next section. lead leakage is like polymer swelling in that it may allow another failure mechanism, like corrosion, to occur more readily. it also causes a systematic pressure measurement error. figure 8 shows the result of lead leakage measurements as a function of temperature cycling. the polymer housing material (and its cte as a function of temperature), the leadframe material (and its cte), surface preparation and contamination, the polymer matrix composition, and polymer processing all contribute to this effect. it is accelerated by media, temperature cycling, and applied pressure. figure 8. pressure leakage measurements through the metallic leadframe/polymeric housing material interface on a pressure sensor as a function of temperature cycles between 40 and 125 c. 0 0.0 0.5 1.0 1.5 2.0 lead leakage (cc/min) temperature cycles epoxy pps grade 1 200 400 600 800 1000 pps grade 2 pbt lcp adhesive strength packaging of the sensor relies on adhesive material to maintain a seal but not impart stress on the piezoresistive element. polymeric materials are the primary adhesive materials which can range from low modulus material such as silicone to epoxy with a high modulus. an example of a typical joint is shown in figure 9. the joint has three possible failure locations with the preferred break being cohesive. contributors to a break include whether the joint is in tension or compression, residual stresses, the adhesive material, surface preparation, and contamination. an adhesive failure is accelerated by media contact, cyclic or static temperature, and cyclic or static stress (e.g. pressure). figure 9. failure locations for an adhesive bond of dissimilar materials. die to epoxy adhesive strength cohesive strength die to mat'l adhesive strength strength components f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
124 motorola sensor device data www.motorola.com/semiconductors mechanical failures the occurrence of mechanical failures include components of fatigue, environment assisted cracking, and creep. packaging materials, process, and residual stresses are all contributors to mechanical failure. a summary of acceleration stresses is shown in table 3. contact with harsh media is an accelerating stress for all of the mechanical failure mechanisms. table 3. mechanical failure mechanisms failure mechanism acceleration stresses fatigue crack initiation mechanical stress/strain range cyclic temperature range frequency media fatigue crack propagation mechanical stress range cyclic temperature range frequency media environment assisted cracking mechanical stress temperature media creep mechanical stress temperature media pressure sensor solutions the range of solutions for pressure sensors to media compatibility is very diverse. mechanical pressure sensors still occupy a number of applications due to this media compatibility concern. these devices typically operate on a variable inductance method and are typically not as linear as a piezoresistive element. figure 10 shows a comparison between a mechanical pressure sensor and a piezoresistive element for a washing machine level sensing application. the graph shows a nonlinear response for the mechanical sensor and a corresponding straight line for the piezoresistive element. a common method of obtaining media compatibility is to place a barrier coating over the die and wire interconnection. this organic encapsulant provides a physical barrier between the harsh environment and the circuitry. the barrier coating can range from silicone to parylene or other dense films that are typically applied as a very thin layer. this technique offers limited protection to some environments due to swelling and/or dissolution of the encapsulant material when in contact with media with a similar solubility. when a polymeric material has a solubility parameter of the same value as the corresponding media, swelling or dissolution will occur. stainless steel diaphragms backfilled with silicone oil provide a rugged barrier to most media environments, but generally are very costly and limit the sensitivity of the device. the silicone oil is used to transmit the stress from the diaphragm to the piezoresistive element. if a polymeric material is used as the die attach, the silicone oil will permeate out of the package. this concern requires a die attach that is typically of higher modulus than a silicone and may not adequately isolate the package stress from the die. figure 10. graphical comparison of the output from a mechanical pressure sensor compared to a piezoresistive sensor during a washing machine fill cycle. 0123456 140 145 150 155 160 165 170 175 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 mechanical sensor output (hertz) piezoresistive pressure sensor output (volts) time (minutes) washing machine sensor piezoresistive pressure sensor f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
125 motorola sensor device data www.motorola.com/semiconductors media test methods figures 11 and 12 show a test apparatus specifically intended for use with solvents and figure 13 an apparatus for aqueous solutions. this test system has resulted in a realistic test environment that provides electrical bias, in situ measurements, consistent stoichiometry, and temperature control all within a safe environment. the safety aspects of the testing were obtained by creating an environment free of oxygen to eliminate the possibility of a fire. results from the testing have included swelling of silicone materials, corrosion, and adhesive failures. figure 11. graphical depiction of the sensor media tester used for liquid or vapor exposure of the device to the harsh media to accelerate the failure mechanisms or demonstrate compatibility. condenser coils sensors to automatic test system loading chamber thermocouples fluorinated hydrocarbon liquid with external heater modular test plate with oring seal to drain to pump from pump tank 1 tank 2 v a p o r l i q u i d lid electrical connections with voltage and current linking protection porous nitrogen purge lines figure 12. photograph of the load chamber area of the media test system allowing for fuel or solvent testing at temperature with in situ monitoring of the devices under test (dut's) output. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
126 motorola sensor device data www.motorola.com/semiconductors figure 13. photograph of the aqueous alkaline solution test system and the data acquisition system for in situ monitoring of the mems devices. lifetime modeling reliability techniques provide a means to analyze media test results and equate the performance to a lifetime [2324]. the primary reliability techniques involve an understanding of the failure rate, life distributions, and acceleration modeling. the failure rate for a product's lifetime follows the bathtub curve. this curve, as shown in figure 14, has an early life period with a decreasing failure rate. manufacturing defects would be an example of failures during this portion of the curve. the second portion of the curve, often described as the useful life region has a constant failure rate. the last section has an increasing failure rate and is referred to as the wearout region. this wearout region would include failure mechanisms such as corrosion or fatigue. figure 14. bathtub curve showing various failure rate regions. product failure rate infant mortality or early life failure rate end of life or wear out failure rate time steady state failure rate lifetime distributions provide a theoretical model to describe device lifetimes. common lifetime distributions include the exponential, weibull, lognormal, and extreme value. the exponential distribution models a lifetime with a constant failure rate an example of the exponential distribution is a glass which has an equal probability of failing the moment after it is manufactured, or when its ten years old. the weibull and lognormal distribution are all right, or f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
127 motorola sensor device data www.motorola.com/semiconductors positively skewed distributions. a right skewed distribution will be a good model for data in a histogram with an extended right tail. the weibull distribution is sometimes referred to as a distribution of minima. an example of a weibull distribution is the strength to break a chain where the weakest link describes the strength of the chain. the extreme value distribution is a distribution of maxima. it is the least utilized of the four life distributions. for means of example, the weibull distribution will be used. the weibull lifetime distribution has the form: f(t, q , b ) 1 e t . (1) the two parameters for the weibull distribution are q and b. theta is the scale parameter, or characteristic life. it represents the 63.2 percentile of the life distribution. beta is the shape parameter. in order to determine the parameters for the weibull distribution, testing must be performed produce failure on the devices. the failure data can be used to calculate the maximum likelihood estimates or determined graphically. it has not always been customary to perform reliability demonstration testing until failures occur. in regards to media testing, this seems to be the only method to derive lifetime estimates that reflect a true understanding of the device capability. (2) af e ea k 1 t low 1 t high ? rh high rh low n , a media test typically needs to take results received in weeks or months to predict lifetime in years. acceleration models are used to determine the relationship between the accelerated test and the normal lifetime. literature has reported numerous models to equate testing to lifetime including the peck model for temperature and humidity [25]. the acceleration equation based on peck's model is where ea is 0.9ev and n is 3.0. the value k is boltzmann's constant which is equal to 8.6171x10 5 ev/k. the relative humidity is entered as a whole number, i.e. 85 for 85%. using this sample model, test results from humidity testing can be related to the lifetime. the methods to equate test time to lifetime first involves fitting the failure data to a lifetime distribution. for an example, humidity data at 60 c, 90% relative humidity and bias was tested to failure. the failure data fit a weibull distribution with a characteristic life of 40,000 hours. by applying the acceleration factor equation shown above, quantification of the lifetime in the use conditions can be calculated. figure 15 shows the cumulative failure distribution for the test and use conditions for a 15 year lifetime. this technique is key for media testing since the range of use conditions is very broad. the consumer can determine the attributes for the sensor to use for the application. the attributes might include cost, performance, and possibility for replacement. figure 15. probability of failure versus time for humidity testing with bias on an integrated sensor device. 0 0% probability of failure, f (t) 10% 30% 20% 40% 50% 60% 70% 80% 90% 100% 1234567891011121314 15 time (years) test condition (60 c, 90% rh) (30 c, 85% rh) (25 c, 60% rh) the failure distribution example shown typically represents one failure mechanism. the failure mechanism that typifies humidity testing is mobile ions. an elevated test temperature, humidity and bias contributes to the mobility of the ions and the ability to create a surface charge. by lowering the temperature, humidity or switching the bias, an improvement in the lifetime can be obtained. if a device manufacturer would test to failure and report the lifetimes, the customer could select the appropriate product for their application. following a template of reliability tests that have not been verified and do not coincide with the applicable failure mechanism may put the application at risk for surviving. humidity testing was used as an example above, but a similar case could be made of other attributes involved with media testing. other attributes of the media test may include the bias level and duty cycle, the ph or conductivity of the solution, and any stress such as a pressure differential. by modeling these attributes against the various solutions, models for media compatibility can be developed. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
128 motorola sensor device data www.motorola.com/semiconductors industry standardization why an industry standard? the increasing use of electronic sensors in everyday life has designers wrestling with the complexity of defining the compatibility of a sensor with the media they are measuring. a designer may decide to solve the question of media compatibility by choosing to isolate the sensor from the media via a stainless steel diaphragm. while this solution provides very good media isolation, it is not without some drawbacks such as cost, size of packaging, decreased sensitivity and long term drift. without a recognized standard for defining media compatibility, the designer is left to a series of ad hoc test methods and conflicting specifications. an industry media compatibility standard will provide the designer with a method of evaluating sensor performance. the designer could match an application's requirements, for media compatibility, with the available sensor products thus taking price and performance into account. this will enable the designer to minimize the total cost of an application. a standard will also enable suppliers to provide products warranted to defined criteria. once a standard is adopted, the suppliers may rationalize their test efforts and pass the savings on to their customers. a standard should provide a designer with a simple, coherent, complete definition of a media's effects on a sensor. the standard should included an accepted test methodology, test equipment guidelines, life time model, acceleration factors model, and a definition of failures. a proposed list of criteria to include in a model are shown in table 4. table 4. suggested criteria for media compatibility media contact e front or back supply voltage solubility parameter pressure range supply voltage duty cycle conductivity of media temperature range voltage potential within media ph recipe of media and contaminants frequency output is measured lifetime expectancy sensor to media interconnection relative motion of media (e.g., flow) these criteria must be included not only for the media, but also for the contaminants in the media. an example is a washing machine level sensor which must be compatible with water vapor (the media) and detergent and chlorine (the contaminant). to create a standard, a series of tests which benchmark the criteria must be designed and performed. the results would form the basis of the life time and acceleration factor models. there are several ways to create a standard, each of which have their own associated pros and cons. three possible ways to create a standard are: an industry association committee, a panel of industry representatives, or a de facto standard set by one or more industry suppliers. to define a standard for media compatibility may require more than one of these methods. an industry leader may define a standard form to which they deliver product. this may stimulate the formation of a committee which defines a broader standard for the industry. as this standard becomes more accepted by the industry, the committee may work with an industry association to alegitimizeo the de facto standard. no matter how the standard is formulated, receiving broad industry acceptance will require meeting the customers' needs. conclusion investigation of media compatibility for pressure sensors has been presented from a physicsoffailure approach. we have developed a set of internal standard test and reliability lifetime analysis procedures to simulate our customers' requirements. these activities have incorporated information from several fields beyond sensors and/or electronics, including: electrochemistry and corrosion, polymers, safety and environmental, automotive and appliance industry standards, and reliability. the next critical step to elevating the awareness of this problem, in our opinion, is to develop an industrywide set of standards, driven by customer applications, that include media testing experimental procedures, reliability lifetime analysis, and media compatibility reporting to allow easier customer interpretation of results. acknowledgments many individuals have contributed to the media compatibility initiative and are deserving of an acknowledgment. the individuals include debi beall, gordon bitko, jerry cripe, bob gailey, jim kasarskis, john keller, betty leung, jeanene matkin, mike menchio, adan ramirez, chuck reed, laura rivers, scott savage, mahesh shah, mario velez, john wertz, mems1, mkl, reliability lab, characterization lab, and the prototype lab. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
129 motorola sensor device data www.motorola.com/semiconductors reference (1) theresa maudie, testing requirements and reliability issues encountered with micromachined structures, proceedings of the second international symposium on microstructures and microfabricated systems, eds. d. denton, p.j. hesketh and h. hughes, ecs, vol. 9527 (1995) pp. 223230. (2) arne nakladal et al ., influences of humidity and mois- ture on the longterm stability of piezoresistive pres- sure sensors, measurement, vol. 16 (1995) pp. 2129. (3) marin nese and anders hanneborg, anodic bonding of silicon to silicon wafers coated with aluminum, silicon oxide, polysilicon or silicon nitride, sensors and actuators a, vol. 3738 (1993) pp. 6167. (4) janusz bryzek, micromachines on the march, ieee spectrum, may 1994. (5) j. m. hu, physicsoffailurebased reliability qualifi- cation of automotive electronics, communications in rms, vol. 1, no. 2 (1994) pp. 2133. (6) michael pecht et.al., quality conformance and qualifi- cation of microelectronics packages and intercon- nects, john wiley & sons, inc., 1994. (7) william m. alvino, plastics for electronics, mcgraw hill, 1995 (8) eugene r. hnatek, integrated circuit quality and reli- ability, marcel dekker, inc., 1987. (9) charles a. harper, handbook of plastics, elastomers, and composites, mcgrawhill, 1992. (10) richard w. hertzberg, deformation and fracture mechanics of engineering materials, john wiley & sons, inc., 1983. (11) joseph m. giachino, automotive sensors: driving toward optimized vehicle performance, 7th int'l con- ference on solid state sensor and actuators, june 1993. (12) perry poiss, what additives do for gasoline, hydro- carbon processing, feb. 1973. (13) gasoline/methanol mixtures for material testing, sae cooperative research report crp001, sep. 1990. (14) private communication to andrew mcneil from city of phoenix, water and wastewater department, water quality division, jan. 1994. (15) laundry detergents, consumer reports, feb. 1991, pp. 100106. (16) silicon as a mechanical material, kurt e. petersen, proc. ieee, vol. 70, no. 5, pp. 420457, may 1982. (17) principles and prevention of corrosion, denny a. jones, (prentice hall: englewood cliffs, nj, 1992). (18) atlas of electrochemical equilibria in aqueous solu- tions, m. pourbaix, (pergamon press: oxford, eng- land, 1966) (19) anisotropic etching of crystalline silicon in alkaline solutions, part i. orientation dependence and behav- ior of passivation layers, h. seidel et al ., j. electro- chem. soc., vol. 137, no. 11 (1990) pp. 36123625. (20) anisotropic etching of crystalline silicon in alkaline solutions, part ii. influence of dopants, h. seidel et al. , j. electrochem. soc., vol. 137, no. 11 (1990) pp. 36123625. (21) principles of polymer systems, 2nd ed., f. rodriguez, (hemisphere publishing corporation: washington, d.c., 1982. (22) d. j. monk, pressure leakage through material inter- faces in pressure sensor packages, sensors in elec- tronic packaging, eds. charles ume and chao pinyeh, medvol. 3/eepvol.14 (1995) pp. 8793. (23) paul a. tobias and david c. trindade, applied reli- ability, van nostrand reinhold, 1995. (24) wayne nelson, accelerated testing, john wiley & sons, inc., 1990. (25) o. hallberg and d. s. peck, arecent humidity accel- erations, a base for testing standards,o quality and reliability engr. international, vol. 7, pp 169180, 1991. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
130 motorola sensor device data www.motorola.com/semiconductors f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
21 motorola sensor device data www.motorola.com/semiconductors
section two accelerometer overview: motorola's series of acceleration sensors incorporate a surface micromachined structure. the force of acceleration moves the seismic mass, thereby changing the gcell's capacitance. coupled with the gcell is a control chip to pro- vide the accelerometer with signal amplification, signal conditioning, low pass filter and temperature compensation. with zerog offset, sensitivity and filter rolloff that is factory set, the device requires only a few external passives. in fact, this acceleration sensor device offers a calibrated selftest feature that mechanically displaces the seismic mass with the application of a digital selftest signal. the gcell is hermetically sealed at the die level, creating a particlefree environment with features such as built in damping and overrange stops to protect it from mechanical shock. these acceleration sensors are rugged, highly accurate and feature x, xy, and z axis of sensitivity. motorola's acceleration sensors are economical, accurate and highly reproducible for the ideal sensing solution in auto- motive, industrial, commercial and consumer applications. mini selector guide 22 . . . . . . . . . . . . . . . . . . . . . . . . . device numbering system 22 . . . . . . . . . . . . . . . . . . sensor applications 23 . . . . . . . . . . . . . . . . . . . . . . . . . acceleration sensor faq's 24 . . . . . . . . . . . . . . . . . . data sheets mma1200d 2 5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mma1201p 212 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mma1220d 2 18 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mma1250d 224 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mma1260d 230 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mma1270d 236 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mma2201d 2 42 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mma2202d 2 48 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mma3201d 2 55 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . application notes an1559 2 62 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . an1611 265 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . an1612 277 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . an1632 2 84 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . an1635 2 89 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . an1640 2101 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . an1925 2 104 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . case outlines 2107 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . glossary of terms 2109 . . . . . . . . . . . . . . . . . . . . . . . . . f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
22 motorola sensor device data www.motorola.com/semiconductors mini selector guide accelerometer sensor device acceleration range (g) sensing axis ac sensitivity (mv/g) vdd supply voltage (typ) (v) zero g output (typ) (v) mma1200d 250g z axis 8.0 5.0 2.5 mma1201p 38g z axis 50 5.0 2.5 mma1220d 8g z axis 250 5.0 2.5 mma1250d 5g z axis 400 5.0 2.5 mma1260d 1.5g z axis 1200 5.0 2.5 mma1270d 2.5g z axis 750 5.0 2.5 mma2200w 38g x axis 50 5.0 2.5 mma2201d 38g x axis 50 5.0 2.5 mma2202d 50g x axis 40 5.0 2.5 mma3201d 38g xy axis 50 5.0 2.5 device numbering system for accelerometers p m m a xxxx d prototype micromachined accelerometer package d soic (surface mount) p 16 pin dip w wingback axis of sensitivity 1000 series e z axis 2000 series e x axis 3000 series e xy axis motorola f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
23 motorola sensor device data www.motorola.com/semiconductors sensor applications automotive applications ? airbags ? rollover detection ? fuel shutoff valve ? crash detection ? suspension control ? vehicle dynamic control ? braking systems ? occupant safety healthcare / fitness applications ? physical therapy ? rehabilitation equipment ? range of body motion measurement ? pedometers ? ergonomics tools ? sports medicine equipment ? sports diagnostic systems industrial / consumer applications ? game pads ? vibration monitoring ? computer hard drive protection ? appliance balance and vibration controls ? seismic detection ? seismic switches ? security systems ? security enhancement equipment ? mouse control for handheld devices ? cell phone menu selection scrolling ? virtual reality input devices ? dead reckoning in navigation systems ? bearing wear monitoring ? inclinometers ? robotics f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
24 motorola sensor device data www.motorola.com/semiconductors acceleration sensor faq's we have discovered that many of our customers have similar questions about certain aspects of our accelerome- ter's technology and operation. here are the most frequently asked questions and answers that have been explained in relatively nontechnical terms. q. what is the gcell? a. the gcell is the acceleration transducer within the accelerometer device. it is hermetically sealed at the wafer level to ensure a contaminant free environment, resulting in superior reliability performance. q. what does the output typically interface with? a. the accelerometer device is designed to interface with an analog to digital converter available on most microcontrol- lers. the output has a 2.5 v dc offset, therefore positive and negative acceleration is measurable. for u nique customer applications, the output voltage can be scaled and shifted to meet requirements using external circuitry. q. what is the resonant frequency of the gcell? a. the resonant frequency of the gcell is much higher than the cutoff frequency of the internal filter. therefore, the resonant frequency of the gcell does not play a role in the accelerometer response. q. what is ratiometricity? a. ratiometricity simply means that the output offset voltage and sensitivity scales linearly with applied supply voltage. that is, as you increase supply voltage the sensitivity and offset increase linearly; as supply voltage decreases, offset and sensitivity decrease linearly. this is a key feature when interfacing to a microcontroller or an a/d converter. ratiometricity allows for system level cancellation of supply induced errors in the analog to digital conversion process. refer to the special features section under the principle of operation for more information. q. is the accelerometer device sensitive to electro static discharge (esd)? a. yes. the accelerometer should be handled like other cmos technology devices. q. can the gcell part alatch''? a. no, overrange stops have been designed into the gcell to prevent latching. (latching is when the middle plate of the gcell sticks to the top or bottom plate.) f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
25 motorola sensor device data www.motorola.com/semiconductors the mma series of silicon capacitive, micromachined accelerometers features signal conditioning, a 4pole low pass filter and temperature compensation. zerog offset full scale span and filter cutoff are factory set and require no external devices. a full system selftest capability verifies system functionality. features ? integral signal conditioning ? linear output ? ratiometric performance ? 4th order bessel filter preserves pulse shape integrity ? calibrated selftest ? low voltage detect, clock monitor, and eprom parity check status ? transducer hermetically sealed at wafer level for superior reliability ? robust design, high shocks survivability typical applications ? vibration monitoring and recording ? impact monitoring simplified accelerometer functional block diagram gcell sensor integrator gain filter temp comp selftest control logic & eprom trim circuits clock gen. oscillator v dd v out v ss st figure 1. simplified accelerometer functional block diagram status rev 0
semiconductor technical data mma1200d: z axis sensitivity micromachined accelerometer 250g 16 lead soic case 475 16 9 1 8 10 11 12 13 14 15 16 8 7 6 5 4 3 2 1 9 n/c n/c n/c st v out status v ss v dd n/c n/c n/c n/c n/c n/c n/c n/c pin assignment f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
26 motorola sensor device data www.motorola.com/semiconductors maximum ratings (maximum ratings are the limits to which the device can be exposed without causing permanent damage.) rating symbol value unit powered acceleration (all axes) g pd 500 g unpowered acceleration (all axes) g upd 2000 g supply voltage v dd 0.3 to +7.0 v drop test (1) d drop 1.2 m storage temperature range t stg 40 to +105 c notes: 1. dropped onto concrete surface from any axis. electro static discharge (esd) warning: this device is sensitive to electrostatic discharge. although the motorola accelerometers contain internal 2kv esd protection circuitry, extra precaution must be taken by the user to protect the chip from esd. a charge of over 2000 volts can accumulate on the human body or associated test equipment. a charge of this magnitude can alter the per- formance or cause failure of the chip. when handling the accelerometer, proper esd precautions should be followed to avoid exposing the device to discharges which may be detrimental to its performance. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
27 motorola sensor device data www.motorola.com/semiconductors operating characteristics (unless otherwise noted: 40 c t a +85 c, 4.75 v dd 5.25, acceleration = 0g, loaded output (1) ) characteristic symbol min typ max unit operating range (2) supply voltage (3) supply current operating temperature range acceleration range v dd i dd t a g fs 4.75 3.0 40 e 5.00 e e 47 5.25 6.0 +85 e v ma c g output signal zero g (v dd = 5.0 v) (4) zero g sensitivity (t a = 25 c, v dd = 5.0 v) (5) sensitivity bandwidth response nonlinearity v off v off,v s s v f 3db nl out 2.2 0.44 v dd 7.5 1.47 360 2.0 2.5 0.50 v dd 8.0 1.6 400 e 2.8 0.56 v dd 8.5 1.72 440 2.0 v v mv/g mv/g/v hz % fso noise rms (.011 khz) power spectral density clock noise (without rc load on output) (6) n rms n psd n clk e e e e 110 2.0 2.8 e e mvrms m v/(hz 1/2 ) mvpk selftest output response input low input high input loading (7) response time (8) g st v il v ih i in t st 55 v ss 0.7 x v dd 30 e 77 e e 100 2.0 95 0.3 x v dd v dd 260 10 g v v m a ms status (12)(13) output low (i load = 100 m a) output high (i load = 100 m a) v ol v oh e v dd .8 e e 0.4 e v v minimum supply voltage (lvd trip) v lvd 2.7 3.25 4.0 v clock monitor fail detection frequency f min 50 e 260 khz output stage performance electrical saturation recovery time (9) full scale output range (i out = 200 m a) capacitive load drive (10) output impedance t delay v fso c l z o e v sst e e 0.2 e e 300 e v dd 0.3 100 e ms v pf w mechanical characteristics transverse sensitivity (11) package resonance v xz,yz f pkg e e e 10 5.0 e % fso khz notes: 1. for a loaded output the measurements are observed after an rc filter consisting of a 1 k w resistor and a 0.01 m f capacitor to ground. 2. these limits define the range of operation for which the part will meet specification. 3. within the supply range of 4.75 and 5.25 volts, the device operates as a fully calibrated linear accelerometer. beyond these supply limits the device may operate as a linear device but is not guaranteed to be in calibration. 4. the device can measure both + and acceleration. with no input acceleration the output is at midsupply. for positive acceleration the output will increase above v dd /2 and for negative acceleration the output will decrease below v dd /2. 5. the device is calibrated at 35g. 6. at clock frequency 70 khz. 7. the digital input pin has an internal pulldown current source to prevent inadvertent self test initiation due to external bo ard level leakages. 8. time for the output to reach 90% of its final value after a selftest is initiated. 9. time for amplifiers to recover after an acceleration signal causing them to saturate. 10. preserves phase margin (60 ) to guarantee output amplifier stability. 11. a measure of the device's ability to reject an acceleration applied 90 from the true axis of sensitivity. 12. the status pin output is not valid following powerup until at least one rising edge has been applied to the selftest pin. the status pin is high whenever the selftest input is high. 13. the status pin output latches high if a low voltage detection or clock frequency failure occurs, or the eprom parity changes to odd. the status pin can be reset by a rising edge on selftest, unless a fault condition continues to exist. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
28 motorola sensor device data www.motorola.com/semiconductors principle of operation the motorola accelerometer is a surfacemicromachined integratedcircuit accelerometer. the device consists of a surface micromachined capaci- tive sensing cell (gcell) and a cmos signal conditioning asic contained in a single integrated circuit package. the sensing element is sealed hermetically at the wafer level using a bulk micromachined acap'' wafer. the gcell is a mechanical structure formed from semicon- ductor materials (polysilicon) using semiconductor pro- cesses (masking and etching). it can be modeled as two stationary plates with a moveable plate inbetween. the center plate can be deflected from its rest position by sub- jecting the system to an acceleration (figure 2). when the center plate deflects, the distance from it to one fixed plate will increase by the same amount that the dis- tance to the other plate decreases. the change in distance is a measure of acceleration. the gcell plates form two backtoback capacitors (figure 3). as the center plate moves with acceleration, the distance between the plates changes and each capacitor's value will change, (c = a e /d). where a is the area of the plate, e is the dielectric constant, and d is the distance between the plates. the cmos asic uses switched capacitor techniques to measure the gcell capacitors and extract the acceleration data from the difference between the two capacitors. the asic also signal conditions and filters (switched capacitor) the signal, providing a high level output voltage that is ratio- metric and proportional to acceleration. acceleration figure 2. transducer physical model figure 3. equivalent circuit model special features filtering the motorola accelerometers contain an onboard 4pole switched capacitor filter. a bessel implementation is used because it provides a maximally flat delay response (linear phase) thus preserving pulse shape integrity. because the fil- ter is realized using switched capacitor techniques, there is no requirement for external passive components (resistors and capacitors) to set the cutoff frequency. selftest the sensor provides a selftest feature that allows the verification of the mechanical and electrical integrity of the accelerometer at any time before or after installation. this feature is critical in applications such as automotive airbag systems where system integrity must be ensured over the life of the vehicle. a fourth aplate'' is used in the gcell as a self test plate. when the user applies a logic high input to the selftest pin, a calibr ated potential is applied across the selftest plate and the moveable plate. the resulting elec- trostatic force (fe = 1 / 2 av 2 /d 2 ) causes the center plate to deflect. the resultant deflection is measured by the accel- erometer's control asic and a proportional output voltage results. this procedure assures that both the mechanical (gcell) and electronic sections of the accelerometer are functioning. ratiometricity ratiometricity simply means that the output offset voltage and sensitivity will scale linearly with applied supply voltage. that is, as you increase supply voltage the sensitivity and offset increase linearly; as supply voltage decreases, offset and sensitivity decrease linearly. this is a key feature when interfacing to a microcontroller or an a/d converter because it provides system level cancellation of supply induced errors in the analog to digital conversion process. status motorola accelerometers include fault detection circuitry and a fault latch. the status pin is an output from the fault latch, or'd with selftest, and is set high whenever one (or more) of the following events occur: ? supply voltage falls below the low voltage detect (lvd) voltage threshold ? clock oscillator falls below the clock monitor minimum frequency ? parity of the eprom bits becomes odd in number. the fault latch can be reset by a rising edge on the self test input pin, unless one (or more) of the fault conditions continues to exist. basic connections 10 11 12 13 14 15 16 8 7 6 5 4 3 2 1 9 n/c n/c n/c st v out status v dd n/c n/c n/c n/c n/c n/c n/c n/c pinout description v ss f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
29 motorola sensor device data www.motorola.com/semiconductors pin no. pin name description 1 thru 3 e redundant v ss . leave uncon- nected. 4 st logic input pin used to initiate selftest. 5 v out output voltage of the accelerome- ter. 6 status logic output pin to indicate fault. 7 v ss the power supply ground. 8 v dd the power supply input. 9 thru 13 trim pins used for factory trim. leave unconnected. 14 thru 16 e no internal connection. leave unconnected. mma1200d st v dd v ss v out output signal r1 1 k w 5 c2 0.01 m f 4 8 7 logic input v dd c1 0.1 m f figure 4. soic accelerometer with recommended connection diagram status 6 pcb layout p0 a/d in v rh v ss v dd st v out v ss v dd 0.01 m f c 1 k w 0.1 m f c 0.1 m f power supply c r c 0.1 m f microcontroller accelerometer figure 5. recommend pcb layout for interfacing accelerometer to microcontroller p1 status notes: ? use a 0.1 m f capacitor on v dd to decouple the power source. ? physical coupling distance of the accelerometer to the microcontroller should be minimal. ? place a ground plane beneath the accelerometer to reduce noise, the ground plane should be attached to all of the open ended terminals shown in figure 4. ? use an rc filter of 1 k w and 0.01 m f on the output of the accelerometer to minimize clock noise (from the switched capacitor filter circuit). ? pcb layout of power and ground should not couple power supply noise. ? accelerometer and microcontroller should not be a high current path. ? a/d sampling rate and any external power supply switching frequency should be selected such that they do not inter- fere with the internal accelerometer sampling frequency. this will prevent aliasing errors. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
210 motorola sensor device data www.motorola.com/semiconductors * when positioned as shown, the earth's gravity will result in a positive 1g output positive acceleration sensing direction z +z direction of earth's gravity field.* side view side view side view z +z ordering information device temperature range case no. package mma1200d 40 to +85 c case 47501 soic16 minimum recommended footprint for surface mounted applications surface mount board layout is a critical portion of the total design. the footprint for the surface mount packages must be the correct size to ensure proper solder connection inter- face between the board and the package. with the correct footprint, the packages will selfalign when subjected to a solder reflow process. it is always recommended to design boards with a solder mask layer to avoid bridging and short- ing between solder pads. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
211 motorola sensor device data www.motorola.com/semiconductors figure 6. footprint soic16 (case 47501) 0.380 in. 9.65 mm 0.050 in. 1.27 mm 0.024 in. 0.610 mm 0.080 in. 2.03 mm f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
212 motorola sensor device data www.motorola.com/semiconductors the mma series of silicon capacitive, micromachined accelerometers features signal conditioning, a 4pole low pass filter and temperature compensation. zerog offset full scale span and filter cutoff are factory set and require no external devices. a full system selftest capability verifies system functionality. features ? integral signal conditioning ? linear output ? ratiometric performance ? 4th order bessel filter preserves pulse shape integrity ? calibrated selftest ? low voltage detect, clock monitor, and eprom parity check status ? transducer hermetically sealed at wafer level for superior reliability ? robust design, high shocks survivability ? two packaging options available: 1) plastic dip for z axis sensing (mma1201p) 2) wingback for x axis sensing (mma2200w) typical applications ? vibration monitoring and recording ? appliance control ? mechanical bearing monitoring ? computer hard drive protection ? computer mouse and joysticks ? virtual reality input devices ? sports diagnostic devices and systems simplified accelerometer functional block diagram gcell sensor integrator gain filter temp comp selftest control logic & eprom trim circuits clock gen. oscillator v dd v out v ss v st figure 1. simplified accelerometer functional block diagram status rev 0
semiconductor technical data dip package case 648c mma1201p mma1201p: z axis sensitivity mma2200w: x axis sensitivity micromachined accelerometer 40g wb package case 456 mma2200w 1 2 3 4 5 6 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
213 motorola sensor device data www.motorola.com/semiconductors maximum ratings (maximum ratings are the limits to which the device can be exposed without causing permanent damage.) rating symbol value unit powered acceleration (all axes) g pd 500 g unpowered acceleration (all axes) g upd 2000 g supply voltage v dd 0.3 to +7.0 v drop test (1) d drop 1.2 m storage temperature range t stg 40 to +105 c notes: 1. dropped onto concrete surface from any axis. electro static discharge (esd) warning: this device is sensitive to electrostatic discharge. although the motorola accelerometers contain internal 2kv esd protection circuitry, extra precaution must be taken by the user to protect the chip from esd. a charge of over 2000 volts can accumulate on the human body or associated test equipment. a charge of this magnitude can alter the per- formance or cause failure of the chip. when handling the accelerometer, proper esd precautions should be followed to avoid exposing the device to discharges which may be detrimental to its performance. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
214 motorola sensor device data www.motorola.com/semiconductors operating characteristics (unless otherwise noted: 40 c t a +85 c, 4.75 v dd 5.25, acceleration = 0g, loaded output (1) ) characteristic symbol min typ max unit operating range (2) supply voltage (3) supply current operating temperature range acceleration range v dd i dd t a g fs 4.75 4.0 40 e 5.00 5.0 e 38 5.25 6.0 +85 e v ma c g output signal zero g (v dd = 5.0 v) (4) zero g sensitivity (t a = 25 c, v dd = 5.0 v) (5) sensitivity (v dd = 5.0 v) bandwidth response nonlinearity v off v off,v s s v f 3db nl out 2.2 0.44 v dd 47.5 9.3 360 1.0 2.5 0.50 v dd 50 10 400 e 2.8 0.56 v dd 52.5 10.7 440 +1.0 v v mv/g mv/g/v hz % fso noise rms (.011 khz) power spectral density clock noise (without rc load on output) (6) n rms n psd n clk e e e e 110 2.0 3.5 e e mvrms m v/(hz 1/2 ) mvpk selftest output response input low input high input loading (7) response time (8) g st v il v ih i in t st 20 v ss 0.7 x v dd 30 e e e e 110 2.0 30 0.3 x v dd v dd 300 10 g v v m a ms status (12)(13) output low (i load = 100 m a) output high (i load = 100 m a) v ol v oh e v dd .8 e e 0.4 e v v minimum supply voltage (lvd trip) v lvd 2.7 3.25 4.0 v clock monitor fail detection frequency f min 50 e 260 khz output stage performance electrical saturation recovery time (9) full scale output range (i out = 200 m a) capacitive load drive (10) output impedance t delay v fso c l z o e 0.3 e e 0.2 e e 300 e v dd 0.3 100 e ms v pf w mechanical characteristics transverse sensitivity (11) package resonance v zx,yx f pkg e e e 10 5.0 e % fso khz notes: 1. for a loaded output the measurements are observed after an rc filter consisting of a 1 k w resistor and a 0.01 m f capacitor to ground. 2. these limits define the range of operation for which the part will meet specification. 3. within the supply range of 4.75 and 5.25 volts, the device operates as a fully calibrated linear accelerometer. beyond these supply limits the device may operate as a linear device but is not guaranteed to be in calibration. 4. the device can measure both + and acceleration. with no input acceleration the output is at midsupply. for positive acceleration the output will increase above v dd /2 and for negative acceleration the output will decrease below v dd /2. 5. the device is calibrated at 20g. 6. at clock frequency 70 khz. 7. the digital input pin has an internal pulldown current source to prevent inadvertent self test initiation due to external bo ard level leakages. 8. time for the output to reach 90% of its final value after a selftest is initiated. 9. time for amplifiers to recover after an acceleration signal causing them to saturate. 10. preserves phase margin (60 ) to guarantee output amplifier stability. 11. a measure of the device's ability to reject an acceleration applied 90 from the true axis of sensitivity. 12. the status pin output is not valid following powerup until at least one rising edge has been applied to the selftest pin. the status pin is high whenever the selftest input is high. 13. the status pin output latches high if a low voltage detection or clock frequency failure occurs, or the eprom parity changes to odd. the status pin can be reset by a rising edge on selftest, unless a fault condition continues to exist. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
215 motorola sensor device data www.motorola.com/semiconductors principle of operation the motorola accelerometer is a surfacemicromachined integratedcircuit accelerometer. the device consists of a surface micromachined capaci- tive sensing cell (gcell) and a cmos signal conditioning asic contained in a single integrated circuit package. the sensing element is sealed hermetically at the wafer level using a bulk micromachined acap'' wafer. the gcell is a mechanical structure formed from semicon- ductor materials (polysilicon) using semiconductor pro- cesses (masking and etching). it can be modeled as two stationary plates with a moveable plate inbetween. the center plate can be deflected from its rest position by sub- jecting the system to an acceleration (figure 2). when the center plate deflects, the distance from it to one fixed plate will increase by the same amount that the dis- tance to the other plate decreases. the change in distance is a measure of acceleration. the gcell plates form two backtoback capacitors (figure 3). as the center plate moves with acceleration, the distance between the plates changes and each capacitor's value will change, (c = a e /d). where a is the area of the plate, e is the dielectric constant, and d is the distance between the plates. the cmos asic uses switched capacitor techniques to measure the gcell capacitors and extract the acceleration data from the difference between the two capacitors. the asic also signal conditions and filters (switched capacitor) the signal, providing a high level output voltage that is ratio- metric and proportional to acceleration. acceleration figure 2. transducer physical model figure 3. equivalent circuit model special features filtering the motorola accelerometers contain an onboard 4pole switched capacitor filter. a bessel implementation is used because it provides a maximally flat delay response (linear phase) thus preserving pulse shape integrity. because the fil- ter is realized using switched capacitor techniques, there is no requirement for external passive components (resistors and capacitors) to set the cutoff frequency. selftest the sensor provides a selftest feature that allows the verification of the mechanical and electrical integrity of the accelerometer at any time before or after installation. this feature is critical in applications such as automotive airbag systems where system integrity must be ensured over the life of the vehicle. a fourth aplate'' is used in the gcell as a self test plate. when the user applies a logic high input to the selftest pin, a calibr ated potential is applied across the selftest plate and the moveable plate. the resulting elec- trostatic force (fe = 1 / 2 av 2 /d 2 ) causes the center plate to deflect. the resultant deflection is measured by the accel- erometer's control asic and a proportional output voltage results. this procedure assures that both the mechanical (gcell) and electronic sections of the accelerometer are functioning. ratiometricity ratiometricity simply means that the output offset voltage and sensitivity will scale linearly with applied supply voltage. that is, as you increase supply voltage the sensitivity and offset increase linearly; as supply voltage decreases, offset and sensitivity decrease linearly. this is a key feature when interfacing to a microcontroller or an a/d converter because it provides system level cancellation of supply induced errors in the analog to digital conversion process. status motorola accelerometers include fault detection circuitry and a fault latch. the status pin is an output from the fault latch, or'd with selftest, and is set high whenever one (or more) of the following events occur: ? supply voltage falls below the low voltage detect (lvd) voltage threshold ? clock oscillator falls below the clock monitor minimum frequency ? parity of the eprom bits becomes odd in number. the fault latch can be reset by a rising edge on the self test input pin, unless one (or more) of the fault conditions continues to exist. basic connections pinout description for the wingback package 1 2 3 4 5 6 pin no. pin name description 1 e leave unconnected or connect to sig- nal ground 2 st logic input pin to initiate self test 3 v out output voltage 4 status logic output pin to indicate fault 5 v ss signal ground 6 v dd supply voltage (5 v) e wings support pins, internally connected to lead frame. tie to v ss . f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
216 motorola sensor device data www.motorola.com/semiconductors mma2200w st v dd v ss v out output signal r1 1 k w 3 c2 0.01 m f 2 6 5 logic input v dd c1 0.1 m f figure 4. wingback accelerometer with recommended connection diagram status 4 pinout description for the dip package 16 15 14 13 12 11 10 9 1 2 3 4 5 6 7 8 n/c n/c n/c st v out status v ss v dd n/c n/c n/c n/c n/c n/c n/c n/c n/c pin no. pin name description 1 e leave unconnected or connect to signal ground. 2 thru 3 e no internal connection. leave un- connected. 4 st logic input pin to initiate self test. 5 v out output voltage 6 status logic output pin to indicate fault. 7 v ss signal ground 8 v dd supply voltage (5 v) 9 thru 13 trim pins used for factory trim. leave un- connected. 14 thru 16 e no internal connection. leave un- connected. mma1201p st v dd v ss v out output signal r1 1 k w 5 c2 0.01 m f 4 8 7 logic input v dd c1 0.1 m f figure 5. dip accelerometer with recommended connection diagram status 6 pcb layout p0 a/d in v rh v ss v dd st v out v ss v dd 0.01 m f c 1 k w 0.1 m f c 0.1 m f power supply c r c 0.1 m f microcontroller accelerometer figure 6. recommend pcb layout for interfacing accelerometer to microcontroller p1 status notes: ? use a 0.1 m f capacitor on v dd to decouple the power source. ? physical coupling distance of the accelerometer to the microcontroller should be minimal. ? place a ground plane beneath the accelerometer to reduce noise, the ground plane should be attached to all of the open ended terminals shown in figure 4. ? use an rc filter of 1 k w and 0.01 m f on the output of the accelerometer to minimize clock noise (from the switched capacitor filter circuit). ? pcb layout of power and ground should not couple power supply noise. ? accelerometer and microcontroller should not be a high current path. ? a/d sampling rate and any external power supply switching frequency should be selected such that they do not inter- fere with the internal accelerometer sampling frequency. this will prevent aliasing errors. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
217 motorola sensor device data www.motorola.com/semiconductors 16 9 18 * dip package * when positioned as shown, the earth's gravity will result in a positive 1g output positive acceleration sensing direction wingback package 12 16 7 * .090 .190 .290 .390 .490 .000 .090 ? .033 measurement in inches drilling patterns wb package drilling pattern .031 6x ? .049 .047 2x .590 .680 ordering information device temperature range case no. package mma1201p 40 to +85 c case 648c04 plastic dip mma2200w 40 to +85 c case 45606 plastic wingback f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
218 motorola sensor device data www.motorola.com/semiconductors the mma series of silicon capacitive, micromachined accelerometers features signal conditioning, a 4pole low pass filter and temperature compensation. zerog offset full scale span and filter cutoff are factory set and require no external devices. a full system selftest capability verifies system functionality. features ? integral signal conditioning ? linear output ? ratiometric performance ? 4th order bessel filter preserves pulse shape integrity ? calibrated selftest ? low voltage detect, clock monitor, and eprom parity check status ? transducer hermetically sealed at wafer level for superior reliability ? robust design, high shock survivability typical applications ? vibration monitoring and recording ? appliance control ? mechanical bearing monitoring ? computer hard drive protection ? computer mouse and joysticks ? virtual reality input devices ? sports diagnostic devices and systems ordering information device temperature range case no. package mma1220d 40 to +85 c case 47501 soic16 simplified accelerometer functional block diagram gcell sensor integrator gain filter temp comp selftest control logic & eprom trim circuits clock gen. oscillator v dd v out v ss st figure 1. simplified accelerometer functional block diagram status rev 0

semiconductor technical data mma1220d: z axis sensitivity micromachined accelerometer 8g 16 lead soic case 475 16 9 1 8 10 11 12 13 14 15 16 8 7 6 5 4 3 2 1 9 n/c n/c n/c st v out status v ss v dd n/c n/c n/c n/c n/c n/c n/c n/c pin assignment f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
219 motorola sensor device data www.motorola.com/semiconductors maximum ratings (maximum ratings are the limits to which the device can be exposed without causing permanent damage.) rating symbol value unit powered acceleration (all axes) g pd 1500 g unpowered acceleration (all axes) g upd 2000 g supply voltage v dd 0.3 to +7.0 v drop test (1) d drop 1.2 m storage temperature range t stg 40 to +105 c notes: 1. dropped onto concrete surface from any axis. electro static discharge (esd) warning: this device is sensitive to electrostatic discharge. although the motorola accelerometers contain internal 2kv esd protection circuitry, extra precaution must be taken by the user to protect the chip from esd. a charge of over 2000 volts can accumulate on the human body or associated test equipment. a charge of this magnitude can alter the per- formance or cause failure of the chip. when handling the accelerometer, proper esd precautions should be followed to avoid exposing the device to discharges which may be detrimental to its performance. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
220 motorola sensor device data www.motorola.com/semiconductors operating characteristics (unless otherwise noted: 40 c t a +85 c, 4.75 v dd 5.25, acceleration = 0g, loaded output (1) ) characteristic symbol min typ max unit operating range (2) supply voltage (3) supply current operating temperature range acceleration range v dd i dd t a g fs 4.75 3.0 40 e 5.00 5.0 e 8.0 5.25 6.0 +85 e v ma c g output signal zero g (v dd = 5.0 v) (4) zero g sensitivity (t a = 25 c, v dd = 5.0 v) (5) sensitivity bandwidth response nonlinearity v off v off,v s s v f 3db nl out 2.25 0.45 v dd 237.5 46.5 150 1.0 2.5 0.50 v dd 250 50 250 e 2.75 0.55 v dd 262.5 53.5 350 +3.0 v v mv/g mv/g/v hz % fso noise rms (10 hz 1 khz) clock noise (without rc load on output) (6) n rms n clk e e e 2.0 6.0 e mvrms mvpk selftest output response input low input high input loading (7) response time (8) v st v il v ih i in t st 0.2 v dd v ss 0.7 v dd 50 e e e e 100 2.0 0.3 v dd 0.3 v dd v dd 200 10 v v v m a ms status (12)(13) output low (i load = 100 m a) output high (i load = 100 m a) v ol v oh e v dd 0.8 e e 0.4 e v v minimum supply voltage (lvd trip) v lvd 2.7 3.25 4.0 v clock monitor fail detection frequency f min 50 e 260 khz output stage performance electrical saturation recovery time (9) full scale output range (i out = 200 m a) capacitive load drive (10) output impedance t delay v fso c l z o e v ss +0.25 e e 2.0 e e 300 e v dd 0.25 100 e ms v pf w mechanical characteristics transverse sensitivity (11) package resonance v xz,yz f pkg e e e 10 5.0 e % fso khz notes: 1. for a loaded output the measurements are observed after an rc filter consisting of a 1 k w resistor and a 0.01 m f capacitor to ground. 2. these limits define the range of operation for which the part will meet specification. 3. within the supply range of 4.75 and 5.25 volts, the device operates as a fully calibrated linear accelerometer. beyond these supply limits the device may operate as a linear device but is not guaranteed to be in calibration. 4. the device can measure both + and acceleration. with no input acceleration the output is at midsupply. for positive acceleration the output will increase above v dd /2 and for negative acceleration the output will decrease below v dd /2. 5. the device is calibrated at 20g, 100 hz. sensitivity limits apply to 0 hz acceleration. 6. at clock frequency 70 khz. 7. the digital input pin has an internal pulldown current source to prevent inadvertent self test initiation due to external bo ard level leakages. 8. time for the output to reach 90% of its final value after a selftest is initiated. 9. time for amplifiers to recover after an acceleration signal causing them to saturate. 10. preserves phase margin (60 ) to guarantee output amplifier stability. 11. a measure of the device's ability to reject an acceleration applied 90 from the true axis of sensitivity. 12. the status pin output is not valid following powerup until at least one rising edge has been applied to the selftest pin. the status pin is high whenever the selftest input is high. 13. the status pin output latches high if a low voltage detection or clock frequency failure occurs, or the eprom parity changes to odd. the status pin can be reset by a rising edge on selftest, unless a fault condition continues to exist. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
221 motorola sensor device data www.motorola.com/semiconductors principle of operation the motorola accelerometer is a surfacemicromachined integratedcircuit accelerometer. the device consists of a surface micromachined capaci- tive sensing cell (gcell) and a cmos signal conditioning asic contained in a single integrated circuit package. the sensing element is sealed hermetically at the wafer level using a bulk micromachined acap'' wafer. the gcell is a mechanical structure formed from semicon- ductor materials (polysilicon) using semiconductor pro- cesses (masking and etching). it can be modeled as two stationary plates with a moveable plate inbetween. the center plate can be deflected from its rest position by sub- jecting the system to an acceleration (figure 2). when the center plate deflects, the distance from it to one fixed plate will increase by the same amount that the dis- tance to the other plate decreases. the change in distance is a measure of acceleration. the gcell plates form two backtoback capacitors (figure 3). as the center plate moves with acceleration, the distance between the plates changes and each capacitor's value will change, (c = a e /d). where a is the area of the plate, e is the dielectric constant, and d is the distance between the plates. the cmos asic uses switched capacitor techniques to measure the gcell capacitors and extract the acceleration data from the difference between the two capacitors. the asic also signal conditions and filters (switched capacitor) the signal, providing a high level output voltage that is ratio- metric and proportional to acceleration. acceleration figure 2. transducer physical model figure 3. equivalent circuit model special features filtering the motorola accelerometers contain an onboard 4pole switched capacitor filter. a bessel implementation is used because it provides a maximally flat delay response (linear phase) thus preserving pulse shape integrity. because the fil- ter is realized using switched capacitor techniques, there is no requirement for external passive components (resistors and capacitors) to set the cutoff frequency. selftest the sensor provides a selftest feature that allows the verification of the mechanical and electrical integrity of the accelerometer at any time before or after installation. this feature is critical in applications such as automotive airbag systems where system integrity must be ensured over the life of the vehicle. a fourth aplate'' is used in the gcell as a self test plate. when the user applies a logic high input to the selftest pin, a calibr ated potential is applied across the selftest plate and the moveable plate. the resulting elec- trostatic force (fe = 1 / 2 av 2 /d 2 ) causes the center plate to deflect. the resultant deflection is measured by the accel- erometer's control asic and a proportional output voltage results. this procedure assures that both the mechanical (gcell) and electronic sections of the accelerometer are functioning. ratiometricity ratiometricity simply means that the output offset voltage and sensitivity will scale linearly with applied supply voltage. that is, as you increase supply voltage the sensitivity and offset increase linearly; as supply voltage decreases, offset and sensitivity decrease linearly. this is a key feature when interfacing to a microcontroller or an a/d converter because it provides system level cancellation of supply induced errors in the analog to digital conversion process. status motorola accelerometers include fault detection circuitry and a fault latch. the status pin is an output from the fault latch, or'd with selftest, and is set high whenever one (or more) of the following events occur: ? supply voltage falls below the low voltage detect (lvd) voltage threshold ? clock oscillator falls below the clock monitor minimum frequency ? parity of the eprom bits becomes odd in number. the fault latch can be reset by a rising edge on the self test input pin, unless one (or more) of the fault conditions continues to exist. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
222 motorola sensor device data www.motorola.com/semiconductors basic connections 10 11 12 13 14 15 16 8 7 6 5 4 3 2 1 9 n/c n/c n/c st v out status v ss v dd n/c n/c n/c n/c n/c n/c n/c n/c pinout description pin no. pin name description 1 thru 3 v ss redundant connections to the internal v ss and may be left unconnected. 4 st logic input pin used to initiate self test. 5 v out output voltage of the accelerometer. 6 status logic output pin used to indicate fault. 7 v ss the power supply ground. 8 v dd the power supply input. 9 thru 13 trim pins used for factory trim. leave unconnected. 14 thru 16 e no internal connection. leave unconnected. mma1220d st v dd v ss v out output signal r1 1 k w 5 c2 0.01 m f 4 8 7 logic input v dd c1 0.1 m f figure 4. soic accelerometer with recommended connection diagram status 6 pcb layout p0 a/d in v rh v ss v dd st v out v ss v dd 0.01 m f c 1 k w 0.1 m f c 0.1 m f power supply c r c 0.1 m f microcontroller accelerometer figure 5. recommended pcb layout for interfacing accelerometer to microcontroller p1 status notes: ? use a 0.1 m f capacitor on v dd to decouple the power source. ? physical coupling distance of the accelerometer to the microcontroller should be minimal. ? place a ground plane beneath the accelerometer to reduce noise, the ground plane should be attached to all of the open ended terminals shown in figure 4. ? use an rc filter of 1 k w and 0.01 m f on the output of the accelerometer to minimize clock noise (from the switched capacitor filter circuit). ? pcb layout of power and ground should not couple power supply noise. ? accelerometer and microcontroller should not be a high current path. ? a/d sampling rate and any external power supply switching frequency should be selected such that they do not inter- fere with the internal accelerometer sampling frequency. this will prevent aliasing errors. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
223 motorola sensor device data www.motorola.com/semiconductors * when positioned as shown, the earth's gravity will result in a positive 1g output acceleration sensing directions 10 11 12 13 14 15 16 8 7 6 5 4 3 2 1 9 n/c n/c n/c st v out status v ss v dd n/c n/c n/c n/c n/c n/c n/c n/c 16pin soic package n/c pins are recommended to be left floating g +g direction of earth's gravity field.* dynamic acceleration static acceleration [ v out > 2.75 ] [ v out < 2.75 ] 1g +1g 0g 0g v out = 2.50v v out = 2.50v v out = 2.75v v out = 2.25v f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
224 motorola sensor device data www.motorola.com/semiconductors
the mma series of silicon capacitive, micromachined accelerometers features signal conditioning, a 2pole low pass filter and temperature compensation. zerog offset full scale span and filter cutoff are factory set and require no external devices. a full system selftest capability verifies system functionality. features ? integral signal conditioning ? linear output ? 2nd order bessel filter ? calibrated selftest ? eprom parity check status ? transducer hermetically sealed at wafer level for superior reliability ? robust design, high shock survivability typical applications ? vibration monitoring and recording ? appliance control ? mechanical bearing monitoring ? computer hard drive protection ? computer mouse and joysticks ? virtual reality input devices ? sports diagnostic devices and systems ordering information device temperature range case no. package mma1250d 40 to +105 c case 47501 soic16 simplified accelerometer functional block diagram gcell sensor integrator gain filter temp comp & gain selftest control logic & eprom trim circuits clock gen. oscillator v dd v out v ss st figure 1. simplified accelerometer functional block diagram status rev 1
semiconductor technical data
mma1250d: z axis sensitivity micromachined accelerometer 5g 16 lead soic case 475 16 9 1 8 10 11 12 13 14 15 16 8 7 6 5 4 3 2 1 9 v ss v ss v ss v out status v dd v ss st n/c n/c n/c n/c n/c n/c n/c n/c pin assignment f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
225 motorola sensor device data www.motorola.com/semiconductors maximum ratings (maximum ratings are the limits to which the device can be exposed without causing permanent damage.) rating symbol value unit powered acceleration (all axes) g pd 1500 g unpowered acceleration (all axes) g upd 2000 g supply voltage v dd 0.3 to +7.0 v drop test (1) h drop 1.2 m storage temperature range t stg 40 to +125 c notes: 1. dropped onto concrete surface from any axis. electro static discharge (esd) warning: this device is sensitive to electrostatic discharge. although the motorola accelerometers contain internal 2kv esd protection circuitry, extra precaution must be taken by the user to protect the chip from esd. a charge of over 2000 volts can accumulate on the human body or associated test equipment. a charge of this magnitude can alter the per- formance or cause failure of the chip. when handling the ac- celerometer, proper esd precautions should be followed to avoid exposing the device to discharges which may be detri- mental to its performance. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
226 motorola sensor device data www.motorola.com/semiconductors operating characteristics (unless otherwise noted: 40 c t a +105 c, 4.75 v dd 5.25, acceleration = 0g, loaded output (1) ) characteristic symbol min typ max unit operating range (2) supply voltage (3) supply current operating temperature range acceleration range v dd i dd t a g fs 4.75 1.1 40 e 5.00 2.1 e 5 5.25 3.0 +105 e v ma c g output signal zero g (t a = 25 c, v dd = 5.0 v) (4) zero g (v dd = 5.0 v) sensitivity (t a = 25 c, v dd = 5.0 v) (5) sensitivity (v dd = 5.0 v) bandwidth response nonlinearity v off v off s s f 3db nl out 2.25 2.0 380 370 42.5 1.0 2.5 2.5 400 400 50 e 2.75 3.0 420 430.1 57.5 +1.0 v v mv/g mv/g hz % fso noise rms (0.1 hz 1.0 khz) spectral density (rms, 0.1 hz 1.0 khz) (6) n rms n sd e e 2.0 700 4.0 e mvrms m g/ hz selftest output response (v dd = 5.0 v) input low input high input loading (7) response time (8) v st v il v ih i in t st 1.0 v ss 0.7 v dd 50 e 1.25 e e 125 10 1.5 0.3 v dd v dd 300 25 v v v m a ms status (12)(13) output low (i load = 100 m a) output high (i load = 100 m a) v ol v oh e v dd 0.8 e e 0.4 e v v output stage performance electrical saturation recovery time (9) full scale output range (i out = 200 m a) capacitive load drive (10) output impedance t delay v fso c l z o e v ss +0.25 e e e e e 50 2.0 v dd 0.25 100 e ms v pf w mechanical characteristics transverse sensitivity (11) v xz,yz e e 5.0 % fso notes: 1. for a loaded output the measurements are observed after an rc filter consisting of a 1 k w resistor and a 0.1 m f capacitor to ground. 2. these limits define the range of operation for which the part will meet specification. 3. within the supply range of 4.75 and 5.25 volts, the device operates as a fully calibrated linear accelerometer. beyond these supply limits the device may operate as a linear device but is not guaranteed to be in calibration. 4. the device can measure both + and acceleration. with no input acceleration the output is at midsupply. for positive acceleration the output will increase above v dd /2 and for negative acceleration the output will decrease below v dd /2. 5. sensitivity limits apply to 0 hz acceleration. 6. at clock frequency 35 khz. 7. the digital input pin has an internal pulldown current source to prevent inadvertent self test initiation due to external bo ard level leakages. 8. time for the output to reach 90% of its final value after a selftest is initiated. 9. time for amplifiers to recover after an acceleration signal causing them to saturate. 10. preserves phase margin (60 ) to guarantee output amplifier stability. 11. a measure of the device's ability to reject an acceleration applied 90 from the true axis of sensitivity. 12. the status pin output is not valid following powerup until at least one rising edge has been applied to the selftest pin. the status pin is high whenever the selftest input is high. 13. the status pin output latches high if the eprom parity changes to odd. the status pin can be reset by a rising edge on self test, unless a fault condition continues to exist. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
227 motorola sensor device data www.motorola.com/semiconductors principle of operation the motorola accelerometer is a surfacemicromachined integratedcircuit accelerometer. the device consists of a surface micromachined capaci- tive sensing cell (gcell) and a cmos signal conditioning asic contained in a single integrated circuit package. the sensing element is sealed hermetically at the wafer level us- ing a bulk micromachined acap'' wafer. the gcell is a mechanical structure formed from semicon- ductor materials (polysilicon) using semiconductor pro- cesses (masking and etching). it can be modeled as two stationary plates with a moveable plate inbetween. the center plate can be deflected from its rest position by sub- jecting the system to an acceleration (figure 2). when the center plate deflects, the distance from it to one fixed plate will increase by the same amount that the dis- tance to the other plate decreases. the change in distance is a measure of acceleration. the gcell plates form two backtoback capacitors (fig- ure 3). as the center plate moves with acceleration, the dis- tance between the plates changes and each capacitor's value will change, (c = a e /d). where a is the area of the plate, e is the dielectric constant, and d is the distance be- tween the plates. the cmos asic uses switched capacitor techniques to measure the gcell capacitors and extract the acceleration data from the difference between the two capacitors. the asic also signal conditions and filters (switched capacitor) the signal, providing a high level output voltage that is ratio- metric and proportional to acceleration. acceleration figure 2. transducer physical model figure 3. equivalent circuit model special features filtering the motorola accelerometers contain an onboard 2pole switched capacitor filter. a bessel implementation is used because it provides a maximally flat delay response (linear phase) thus preserving pulse shape integrity. because the fil- ter is realized using switched capacitor techniques, there is no requirement for external passive components (resistors and capacitors) to set the cutoff frequency. selftest the sensor provides a selftest feature that allows the ver- ification of the mechanical and electrical integrity of the ac- celerometer at any time before or after installation. this feature is critical in applications such as automotive airbag systems where system integrity must be ensured over the life of the vehicle. a fourth aplate'' is used in the gcell as a self test plate. when the user applies a logic high input to the selftest pin, a calibr ated potential is applied across the selftest plate and the moveable plate. the resulting elec- trostatic force (fe = 1 / 2 av 2 /d 2 ) causes the center plate to deflect. the resultant deflection is measured by the accel- erometer's control asic and a proportional output voltage re- sults. this procedure assures that both the mechanical (gcell) and electronic sections of the accelerometer are functioning. status motorola accelerometers include fault detection circuitry and a fault latch. the status pin is an output from the fault latch, or'd with selftest, and is set high whenever the fol- lowing event occurs: ? parity of the eprom bits becomes odd in number. the fault latch can be reset by a rising edge on the self test input pin, unless one (or more) of the fault conditions continues to exist. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
228 motorola sensor device data www.motorola.com/semiconductors basic connections 10 11 12 13 14 15 16 8 7 6 5 4 3 2 1 9 v ss v ss v ss v out status v dd v ss st n/c n/c n/c n/c n/c n/c n/c n/c figure 4. pinout description pin no. pin name description 1 thru 3 v ss redundant connections to the internal v ss and may be left unconnected. 4 v out output voltage of the accelerometer. 5 status logic output pin used to indicate fault. 6 v dd the power supply input. 7 v ss the power supply ground. 8 st logic input pin used to initiate self test. 9 thru 13 trim pins used for factory trim. leave unconnected. 14 thru 16 e no internal connection. leave unconnected. mma1250d st v dd v ss v out output signal r1 1 k w 4 c2 0.1 m f 8 6 7 logic input v dd c1 0.1 m f figure 5. soic accelerometer with recommended connection diagram status 5 3 2 1 v ss v ss v ss pcb layout p0 a/d in v rh v ss v dd st v out v ss v dd 0.1 m f c 1 k w 0.1 m f c 0.1 m f power supply c r c 0.1 m f microcontroller accelerometer figure 6. recommended pcb layout for interfacing accelerometer to microcontroller p1 status notes: ? use a 0.1 m f capacitor on v dd to decouple the power source. ? physical coupling distance of the accelerometer to the mi- crocontroller should be minimal. ? place a ground plane beneath the accelerometer to reduce noise, the ground plane should be attached to all internal v ss terminals shown in figure 4. ? use an rc filter of 1 k w and 0.1 m f on the output of the ac- celerometer to minimize clock noise (from the switched capacitor filter circuit). ? pcb layout of power and ground should not couple power supply noise. ? accelerometer and microcontroller should not be a high current path. ? a/d sampling rate and any external power supply switching frequency should be selected such that they do not inter- fere with the internal accelerometer sampling frequency. this will prevent aliasing errors. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
229 motorola sensor device data www.motorola.com/semiconductors * when positioned as shown, the earth's gravity will result in a positive 1g output acceleration sensing directions 10 11 12 13 14 15 16 8 7 6 5 4 3 2 1 9 v ss v ss v ss v out status v dd v ss st n/c n/c n/c n/c n/c n/c n/c n/c 16pin soic package n/c pins are recommended to be left floating g +g direction of earth's gravity field.* dynamic acceleration static acceleration 1g +1g 0g 0g v out = 2.50v v out = 2.50v v out = 2.9v v out = 2.1v f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
230 motorola sensor device data www.motorola.com/semiconductors
the mma series of silicon capacitive, micromachined accelerometers features signal conditioning, a 2pole low pass filter and temperature compensation. zerog offset full scale span and filter cutoff are factory set and require no external devices. a full system selftest capability verifies system functionality. features ? integral signal conditioning ? linear output ? 2nd order bessel filter ? calibrated selftest ? eprom parity check status ? transducer hermetically sealed at wafer level for superior reliability ? robust design, high shock survivability typical applications ? vibration monitoring and recording ? appliance control ? mechanical bearing monitoring ? computer hard drive protection ? computer mouse and joysticks ? virtual reality input devices ? sports diagnostic devices and systems ordering information device temperature range case no. package mma1260d 40 to +105 c case 47501 soic16 simplified accelerometer functional block diagram gcell sensor integrator gain filter temp comp & gain selftest control logic & eprom trim circuits clock gen. oscillator v dd v out v ss st figure 1. simplified accelerometer functional block diagram status rev 1
semiconductor technical data
mma1260d: z axis sensitivity micromachined accelerometer 1.5g 16 lead soic case 475 16 9 1 8 10 11 12 13 14 15 16 8 7 6 5 4 3 2 1 9 v ss v ss v ss v out status v dd v ss st n/c n/c n/c n/c n/c n/c n/c n/c pin assignment f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
231 motorola sensor device data www.motorola.com/semiconductors maximum ratings (maximum ratings are the limits to which the device can be exposed without causing permanent damage.) rating symbol value unit powered acceleration (all axes) g pd 1500 g unpowered acceleration (all axes) g upd 2000 g supply voltage v dd 0.3 to +7.0 v drop test (1) h drop 1.2 m storage temperature range t stg 40 to +125 c notes: 1. dropped onto concrete surface from any axis. electro static discharge (esd) warning: this device is sensitive to electrostatic discharge. although the motorola accelerometers contain internal 2kv esd protection circuitry, extra precaution must be taken by the user to protect the chip from esd. a charge of over 2000 volts can accumulate on the human body or associated test equipment. a charge of this magnitude can alter the per- formance or cause failure of the chip. when handling the ac- celerometer, proper esd precautions should be followed to avoid exposing the device to discharges which may be detri- mental to its performance. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
232 motorola sensor device data www.motorola.com/semiconductors operating characteristics (unless otherwise noted: 40 c t a +105 c, 4.75 v dd 5.25, acceleration = 0g, loaded output (1) ) characteristic symbol min typ max unit operating range (2) supply voltage (3) supply current operating temperature range acceleration range v dd i dd t a g fs 4.75 1.1 40 e 5.00 2.2 e 1.5 5.25 3.2 +105 e v ma c g output signal zero g (t a = 25 c, v dd = 5.0 v) (4) zero g (v dd = 5.0 v) sensitivity (t a = 25 c, v dd = 5.0 v) (5) sensitivity (v dd = 5.0 v) bandwidth response nonlinearity v off v off s s f 3db nl out 2.25 2.2 1140 1110 40 1.0 2.5 2.5 1200 1200 50 e 2.75 2.8 1260 1290 60 +1.0 v v mv/g mv/g hz % fso noise rms (0.1 hz 1.0 khz) spectral density (rms, 0.1 hz 1.0 khz) (6) n rms n sd e e 5.0 500 9.0 e mvrms m g/ hz selftest output response (v dd = 5.0 v) input low input high input loading (7) response time (8) v st v il v ih i in t st 0.3 v ss 0.7 v dd 50 e 0.6 e e 125 10 0.9 0.3 v dd v dd 300 25 v v v m a ms status (12)(13) output low (i load = 100 m a) output high (i load = 100 m a) v ol v oh e v dd 0.8 e e 0.4 e v v output stage performance electrical saturation recovery time (9) full scale output range (i out = 200 m a) capacitive load drive (10) output impedance t delay v fso c l z o e v ss +0.25 e e e e e 50 2.0 v dd 0.25 100 e ms v pf w mechanical characteristics transverse sensitivity (11) v xz,yz e e 5.0 % fso notes: 1. for a loaded output the measurements are observed after an rc filter consisting of a 1 k w resistor and a 0.1 m f capacitor to ground. 2. these limits define the range of operation for which the part will meet specification. 3. within the supply range of 4.75 and 5.25 volts, the device operates as a fully calibrated linear accelerometer. beyond these supply limits the device may operate as a linear device but is not guaranteed to be in calibration. 4. the device can measure both + and acceleration. with no input acceleration the output is at midsupply. for positive acceleration the output will increase above v dd /2 and for negative acceleration the output will decrease below v dd /2. 5. sensitivity limits apply to 0 hz acceleration. 6. at clock frequency 35 khz. 7. the digital input pin has an internal pulldown current source to prevent inadvertent self test initiation due to external bo ard level leakages. 8. time for the output to reach 90% of its final value after a selftest is initiated. 9. time for amplifiers to recover after an acceleration signal causing them to saturate. 10. preserves phase margin (60 ) to guarantee output amplifier stability. 11. a measure of the device's ability to reject an acceleration applied 90 from the true axis of sensitivity. 12. the status pin output is not valid following powerup until at least one rising edge has been applied to the selftest pin. the status pin is high whenever the selftest input is high. 13. the status pin output latches high if the eprom parity changes to odd. the status pin can be reset by a rising edge on self test, unless a fault condition continues to exist. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
233 motorola sensor device data www.motorola.com/semiconductors principle of operation the motorola accelerometer is a surfacemicromachined integratedcircuit accelerometer. the device consists of a surface micromachined capaci- tive sensing cell (gcell) and a cmos signal conditioning asic contained in a single integrated circuit package. the sensing element is sealed hermetically at the wafer level us- ing a bulk micromachined acap'' wafer. the gcell is a mechanical structure formed from semicon- ductor materials (polysilicon) using semiconductor pro- cesses (masking and etching). it can be modeled as two stationary plates with a moveable plate inbetween. the center plate can be deflected from its rest position by sub- jecting the system to an acceleration (figure 2). when the center plate deflects, the distance from it to one fixed plate will increase by the same amount that the dis- tance to the other plate decreases. the change in distance is a measure of acceleration. the gcell plates form two backtoback capacitors (fig- ure 3). as the center plate moves with acceleration, the dis- tance between the plates changes and each capacitor's value will change, (c = a e /d). where a is the area of the plate, e is the dielectric constant, and d is the distance be- tween the plates. the cmos asic uses switched capacitor techniques to measure the gcell capacitors and extract the acceleration data from the difference between the two capacitors. the asic also signal conditions and filters (switched capacitor) the signal, providing a high level output voltage that is ratio- metric and proportional to acceleration. acceleration figure 2. transducer physical model figure 3. equivalent circuit model special features filtering the motorola accelerometers contain an onboard 2pole switched capacitor filter. a bessel implementation is used because it provides a maximally flat delay response (linear phase) thus preserving pulse shape integrity. because the fil- ter is realized using switched capacitor techniques, there is no requirement for external passive components (resistors and capacitors) to set the cutoff frequency. selftest the sensor provides a selftest feature that allows the ver- ification of the mechanical and electrical integrity of the ac- celerometer at any time before or after installation. this feature is critical in applications such as automotive airbag systems where system integrity must be ensured over the life of the vehicle. a fourth aplate'' is used in the gcell as a self test plate. when the user applies a logic high input to the selftest pin, a calibr ated potential is applied across the selftest plate and the moveable plate. the resulting elec- trostatic force (fe = 1 / 2 av 2 /d 2 ) causes the center plate to deflect. the resultant deflection is measured by the accel- erometer's control asic and a proportional output voltage re- sults. this procedure assures that both the mechanical (gcell) and electronic sections of the accelerometer are functioning. status motorola accelerometers include fault detection circuitry and a fault latch. the status pin is an output from the fault latch, or'd with selftest, and is set high whenever the fol- lowing event occurs: ? parity of the eprom bits becomes odd in number. the fault latch can be reset by a rising edge on the self test input pin, unless one (or more) of the fault conditions continues to exist. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
234 motorola sensor device data www.motorola.com/semiconductors basic connections 10 11 12 13 14 15 16 8 7 6 5 4 3 2 1 9 v ss v ss v ss v out status v dd v ss st n/c n/c n/c n/c n/c n/c n/c n/c figure 4. pinout description pin no. pin name description 1 thru 3 v ss redundant connections to the internal v ss and may be left unconnected. 4 v out output voltage of the accelerometer. 5 status logic output pin used to indicate fault. 6 v dd the power supply input. 7 v ss the power supply ground. 8 st logic input pin used to initiate self test. 9 thru 13 trim pins used for factory trim. leave unconnected. 14 thru 16 e no internal connection. leave unconnected. figure 5. soic accelerometer with recommended connection diagram mma1260d st v dd v ss v out output signal r1 1 k w 4 c2 0.1 m f 8 6 7 logic input v dd c1 0.1 m f status 5 3 2 1 v ss v ss v ss pcb layout p0 a/d in v rh v ss v dd st v out v ss v dd 0.1 m f c 1 k w 0.1 m f c 0.1 m f power supply c r c 0.1 m f microcontroller accelerometer figure 6. recommended pcb layout for interfacing accelerometer to microcontroller p1 status notes: ? use a 0.1 m f capacitor on v dd to decouple the power source. ? physical coupling distance of the accelerometer to the mi- crocontroller should be minimal. ? place a ground plane beneath the accelerometer to reduce noise, the ground plane should be attached to all internal v ss terminals shown in figure 4. ? use an rc filter of 1 k w and 0.1 m f on the output of the ac- celerometer to minimize clock noise (from the switched capacitor filter circuit). ? pcb layout of power and ground should not couple power supply noise. ? accelerometer and microcontroller should not be a high current path. ? a/d sampling rate and any external power supply switching frequency should be selected such that they do not inter- fere with the internal accelerometer sampling frequency. this will prevent aliasing errors. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
235 motorola sensor device data www.motorola.com/semiconductors * when positioned as shown, the earth's gravity will result in a positive 1g output acceleration sensing directions 10 11 12 13 14 15 16 8 7 6 5 4 3 2 1 9 v ss v ss v ss v out status v dd v ss st n/c n/c n/c n/c n/c n/c n/c n/c 16pin soic package n/c pins are recommended to be left floating g +g direction of earth's gravity field.* dynamic acceleration static acceleration 1g +1g 0g 0g v out = 2.50v v out = 2.50v v out = 3.7v v out = 1.3v f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
236 motorola sensor device data www.motorola.com/semiconductors
the mma series of silicon capacitive, micromachined accelerometers features signal conditioning, a 2pole low pass filter and temperature compensation. zerog offset full scale span and filter cutoff are factory set and require no external devices. a full system selftest capability verifies system functionality. features ? integral signal conditioning ? linear output ? 2nd order bessel filter ? calibrated selftest ? eprom parity check status ? transducer hermetically sealed at wafer level for superior reliability ? robust design, high shock survivability typical applications ? vibration monitoring and recording ? appliance control ? mechanical bearing monitoring ? computer hard drive protection ? computer mouse and joysticks ? virtual reality input devices ? sports diagnostic devices and systems ordering information device temperature range case no. package mma1270d 40 to +105 c case 47501 soic16 simplified accelerometer functional block diagram gcell sensor integrator gain filter temp comp & gain selftest control logic & eprom trim circuits clock gen. oscillator v dd v out v ss st figure 1. simplified accelerometer functional block diagram status rev 1
semiconductor technical data
mma1270d: z axis sensitivity micromachined accelerometer 2.5g 16 lead soic case 475 16 9 1 8 10 11 12 13 14 15 16 8 7 6 5 4 3 2 1 9 v ss v ss v ss v out status v dd v ss st n/c n/c n/c n/c n/c n/c n/c n/c pin assignment f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
237 motorola sensor device data www.motorola.com/semiconductors maximum ratings (maximum ratings are the limits to which the device can be exposed without causing permanent damage.) rating symbol value unit powered acceleration (all axes) g pd 1500 g unpowered acceleration (all axes) g upd 2000 g supply voltage v dd 0.3 to +7.0 v drop test (1) h drop 1.2 m storage temperature range t stg 40 to +125 c notes: 1. dropped onto concrete surface from any axis. electro static discharge (esd) warning: this device is sensitive to electrostatic discharge. although the motorola accelerometers contain internal 2kv esd protection circuitry, extra precaution must be taken by the user to protect the chip from esd. a charge of over 2000 volts can accumulate on the human body or associated test equipment. a charge of this magnitude can alter the per- formance or cause failure of the chip. when handling the ac- celerometer, proper esd precautions should be followed to avoid exposing the device to discharges which may be detri- mental to its performance. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
238 motorola sensor device data www.motorola.com/semiconductors operating characteristics (unless otherwise noted: 40 c t a +105 c, 4.75 v dd 5.25, acceleration = 0g, loaded output (1) ) characteristic symbol min typ max unit operating range (2) supply voltage (3) supply current operating temperature range acceleration range v dd i dd t a g fs 4.75 1.1 40 e 5.00 2.1 e 2.5 5.25 3.0 +105 e v ma c g output signal zero g (t a = 25 c, v dd = 5.0 v) (4) zero g (v dd = 5.0 v) sensitivity (t a = 25 c, v dd = 5.0 v) (5) sensitivity(v dd = 5.0 v) bandwidth response nonlinearity v off v off s s f 3db nl out 2.25 2.2 712.5 693.8 40 1.0 2.5 2.5 750 750 50 e 2.75 2.8 787.5 806.3 60 +1.0 v v mv/g mv/g hz % fso noise rms (0.1 hz 1.0 khz) spectral density (rms, 0.1 hz 1.0 khz) (6) n rms n sd e e 3.5 700 6.5 e mvrms m g/ hz selftest output response (v dd = 5.0 v) input low input high input loading (7) response time (8) v st v il v ih i in t st 0.9 v ss 0.7 v dd 50 e 1.25 e e 125 10 1.6 0.3 v dd v dd 300 25 v v v m a ms status (12)(13) output low (i load = 100 m a) output high (i load = 100 m a) v ol v oh e v dd 0.8 e e 0.4 e v v output stage performance electrical saturation recovery time (9) full scale output range (i out = 200 m a) capacitive load drive (10) output impedance t delay v fso c l z o e v ss +0.25 e e e e e 50 2.0 v dd 0.25 100 e ms v pf w mechanical characteristics transverse sensitivity (11) v xz,yz e e 5.0 % fso notes: 1. for a loaded output the measurements are observed after an rc filter consisting of a 1 k w resistor and a 0.1 m f capacitor to ground. 2. these limits define the range of operation for which the part will meet specification. 3. within the supply range of 4.75 and 5.25 volts, the device operates as a fully calibrated linear accelerometer. beyond these supply limits the device may operate as a linear device but is not guaranteed to be in calibration. 4. the device can measure both + and acceleration. with no input acceleration the output is at midsupply. for positive acceleration the output will increase above v dd /2 and for negative acceleration the output will decrease below v dd /2. 5. sensitivity limits apply to 0 hz acceleration. 6. at clock frequency 35 khz. 7. the digital input pin has an internal pulldown current source to prevent inadvertent self test initiation due to external bo ard level leakages. 8. time for the output to reach 90% of its final value after a selftest is initiated. 9. time for amplifiers to recover after an acceleration signal causing them to saturate. 10. preserves phase margin (60 ) to guarantee output amplifier stability. 11. a measure of the device's ability to reject an acceleration applied 90 from the true axis of sensitivity. 12. the status pin output is not valid following powerup until at least one rising edge has been applied to the selftest pin. the status pin is high whenever the selftest input is high. 13. the status pin output latches high if the eprom parity changes to odd. the status pin can be reset by a rising edge on self test, unless a fault condition continues to exist. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
239 motorola sensor device data www.motorola.com/semiconductors principle of operation the motorola accelerometer is a surfacemicromachined integratedcircuit accelerometer. the device consists of a surface micromachined capaci- tive sensing cell (gcell) and a cmos signal conditioning asic contained in a single integrated circuit package. the sensing element is sealed hermetically at the wafer level us- ing a bulk micromachined acap'' wafer. the gcell is a mechanical structure formed from semicon- ductor materials (polysilicon) using semiconductor pro- cesses (masking and etching). it can be modeled as two stationary plates with a moveable plate inbetween. the center plate can be deflected from its rest position by sub- jecting the system to an acceleration (figure 2). when the center plate deflects, the distance from it to one fixed plate will increase by the same amount that the dis- tance to the other plate decreases. the change in distance is a measure of acceleration. the gcell plates form two backtoback capacitors (fig- ure 3). as the center plate moves with acceleration, the dis- tance between the plates changes and each capacitor's value will change, (c = a e /d). where a is the area of the plate, e is the dielectric constant, and d is the distance be- tween the plates. the cmos asic uses switched capacitor techniques to measure the gcell capacitors and extract the acceleration data from the difference between the two capacitors. the asic also signal conditions and filters (switched capacitor) the signal, providing a high level output voltage that is ratio- metric and proportional to acceleration. acceleration figure 2. transducer physical model figure 3. equivalent circuit model special features filtering the motorola accelerometers contain an onboard 2pole switched capacitor filter. a bessel implementation is used because it provides a maximally flat delay response (linear phase) thus preserving pulse shape integrity. because the fil- ter is realized using switched capacitor techniques, there is no requirement for external passive components (resistors and capacitors) to set the cutoff frequency. selftest the sensor provides a selftest feature that allows the ver- ification of the mechanical and electrical integrity of the ac- celerometer at any time before or after installation. this feature is critical in applications such as automotive airbag systems where system integrity must be ensured over the life of the vehicle. a fourth aplate'' is used in the gcell as a self test plate. when the user applies a logic high input to the selftest pin, a calibr ated potential is applied across the selftest plate and the moveable plate. the resulting elec- trostatic force (fe = 1 / 2 av 2 /d 2 ) causes the center plate to deflect. the resultant deflection is measured by the accel- erometer's control asic and a proportional output voltage re- sults. this procedure assures that both the mechanical (gcell) and electronic sections of the accelerometer are functioning. status motorola accelerometers include fault detection circuitry and a fault latch. the status pin is an output from the fault latch, or'd with selftest, and is set high whenever the fol- lowing event occurs: ? parity of the eprom bits becomes odd in number. the fault latch can be reset by a rising edge on the self test input pin, unless one (or more) of the fault conditions continues to exist. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
240 motorola sensor device data www.motorola.com/semiconductors basic connections 10 11 12 13 14 15 16 8 7 6 5 4 3 2 1 9 v ss v ss v ss v out status v dd v ss st n/c n/c n/c n/c n/c n/c n/c n/c figure 4. pinout description pin no. pin name description 1 thru 3 v ss redundant connections to the internal v ss and may be left unconnected. 4 v out output voltage of the accelerometer. 5 status logic output pin used to indicate fault. 6 v dd the power supply input. 7 v ss the power supply ground. 8 st logic input pin used to initiate self test. 9 thru 13 trim pins used for factory trim. leave unconnected. 14 thru 16 e no internal connection. leave unconnected. figure 5. soic accelerometer with recommended connection diagram mma1270d st v dd v ss v out output signal r1 1 k w 4 c2 0.1 m f 8 6 7 logic input v dd c1 0.1 m f status 5 3 2 1 v ss v ss v ss pcb layout p0 a/d in v rh v ss v dd st v out v ss v dd 0.1 m f c 1 k w 0.1 m f c 0.1 m f power supply c r c 0.1 m f microcontroller accelerometer figure 6. recommended pcb layout for interfacing accelerometer to microcontroller p1 status notes: ? use a 0.1 m f capacitor on v dd to decouple the power source. ? physical coupling distance of the accelerometer to the mi- crocontroller should be minimal. ? place a ground plane beneath the accelerometer to reduce noise, the ground plane should be attached to all internal v ss terminals shown in figure 4. ? use an rc filter of 1 k w and 0.1 m f on the output of the ac- celerometer to minimize clock noise (from the switched capacitor filter circuit). ? pcb layout of power and ground should not couple power supply noise. ? accelerometer and microcontroller should not be a high current path. ? a/d sampling rate and any external power supply switching frequency should be selected such that they do not inter- fere with the internal accelerometer sampling frequency. this will prevent aliasing errors. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
241 motorola sensor device data www.motorola.com/semiconductors * when positioned as shown, the earth's gravity will result in a positive 1g output acceleration sensing directions 10 11 12 13 14 15 16 8 7 6 5 4 3 2 1 9 v ss v ss v ss v out status v dd v ss st n/c n/c n/c n/c n/c n/c n/c n/c 16pin soic package n/c pins are recommended to be left floating g +g direction of earth's gravity field.* dynamic acceleration static acceleration 1g +1g 0g 0g v out = 2.50v v out = 2.50v v out = 3.25v v out = 1.75v f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
242 motorola sensor device data www.motorola.com/semiconductors the mma series of silicon capacitive, micromachined accelerometers features signal conditioning, a 4pole low pass filter and temperature compensation. zerog offset full scale span and filter cutoff are factory set and require no external devices. a full system selftest capability verifies system functionality. features ? integral signal conditioning ? linear output ? ratiometric performance ? 4th order bessel filter preserves pulse shape integrity ? calibrated selftest ? low voltage detect, clock monitor, and eprom parity check status ? transducer hermetically sealed at wafer level for superior reliability ? robust design, high shocks survivability typical applications ? vibration monitoring and recording ? appliance control ? mechanical bearing monitoring ? computer hard drive protection ? computer mouse and joysticks ? virtual reality input devices ? sports diagnostic devices and systems simplified accelerometer functional block diagram gcell sensor integrator gain filter temp comp selftest control logic & eprom trim circuits clock gen. oscillator v dd v out v ss v st figure 1. simplified accelerometer functional block diagram status rev 0
semiconductor technical data mma2201d: x axis sensitivity micromachined accelerometer 40g 16 lead soic case 475 16 9 1 8 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
243 motorola sensor device data www.motorola.com/semiconductors maximum ratings (maximum ratings are the limits to which the device can be exposed without causing permanent damage.) rating symbol value unit powered acceleration (all axes) g pd 500 g unpowered acceleration (all axes) g upd 2000 g supply voltage v dd 0.3 to +7.0 v drop test (1) d drop 1.2 m storage temperature range t stg 40 to +105 c notes: 1. dropped onto concrete surface from any axis. electro static discharge (esd) warning: this device is sensitive to electrostatic discharge. although the motorola accelerometers contain internal 2kv esd protection circuitry, extra precaution must be taken by the user to protect the chip from esd. a charge of over 2000 volts can accumulate on the human body or associated test equipment. a charge of this magnitude can alter the per- formance or cause failure of the chip. when handling the accelerometer, proper esd precautions should be followed to avoid exposing the device to discharges which may be detrimental to its performance. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
244 motorola sensor device data www.motorola.com/semiconductors operating characteristics (unless otherwise noted: 40 c t a +85 c, 4.75 v dd 5.25, acceleration = 0g, loaded output (1) ) characteristic symbol min typ max unit operating range (2) supply voltage (3) supply current operating temperature range acceleration range v dd i dd t a g fs 4.75 4.0 40 e 5.00 5.0 e 38 5.25 6.0 +85 e v ma c g output signal zero g (v dd = 5.0 v) (4) zero g sensitivity (t a = 25 c, v dd = 5.0 v) (5) sensitivity bandwidth response nonlinearity v off v off,v s s v f 3db nl out 2.3 0.44 v dd 47.5 9.3 360 1.0 2.5 0.50 v dd 50 10 400 e 2.7 0.56 v dd 52.5 10.7 440 +1.0 v v mv/g mv/g/v hz % fso noise rms (.011 khz) power spectral density clock noise (without rc load on output) (6) n rms n psd n clk e e e e 110 2.0 2.8 e e mvrms m v/(hz 1/2 ) mvpk selftest output response input low input high input loading (7) response time (8) g st v il v ih i in t st 10 v ss 0.7 x v dd 30 e 12 e e 110 2.0 14 0.3 x v dd v dd 300 10 g v v m a ms status (12)(13) output low (i load = 100 m a) output high (i load = 100 m a) v ol v oh e v dd .8 e e 0.4 e v v minimum supply voltage (lvd trip) v lvd 2.7 3.25 4.0 v clock monitor fail detection frequency f min 150 e 400 khz output stage performance electrical saturation recovery time (9) full scale output range (i out = 200 m a) capacitive load drive (10) output impedance t delay v fso c l z o e 0.3 e e 0.2 e e 300 e v dd 0.3 100 e ms v pf w mechanical characteristics transverse sensitivity (11) package resonance v zx,yx f pkg e e e 10 5.0 e % fso khz notes: 1. for a loaded output the measurements are observed after an rc filter consisting of a 1 k w resistor and a 0.01 m f capacitor to ground. 2. these limits define the range of operation for which the part will meet specification. 3. within the supply range of 4.75 and 5.25 volts, the device operates as a fully calibrated linear accelerometer. beyond these supply limits the device may operate as a linear device but is not guaranteed to be in calibration. 4. the device can measure both + and acceleration. with no input acceleration the output is at midsupply. for positive acceleration the output will increase above v dd /2 and for negative acceleration the output will decrease below v dd /2. 5. the device is calibrated at 20g. 6. at clock frequency 70 khz. 7. the digital input pin has an internal pulldown current source to prevent inadvertent self test initiation due to external bo ard level leakages. 8. time for the output to reach 90% of its final value after a selftest is initiated. 9. time for amplifiers to recover after an acceleration signal causing them to saturate. 10. preserves phase margin (60 ) to guarantee output amplifier stability. 11. a measure of the device's ability to reject an acceleration applied 90 from the true axis of sensitivity. 12. the status pin output is not valid following powerup until at least one rising edge has been applied to the selftest pin. the status pin is high whenever the selftest input is high. 13. the status pin output latches high if a low voltage detection or clock frequency failure occurs, or the eprom parity changes to odd. the status pin can be reset by a rising edge on selftest, unless a fault condition continues to exist. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
245 motorola sensor device data www.motorola.com/semiconductors principle of operation the motorola accelerometer is a surfacemicromachined integratedcircuit accelerometer. the device consists of a surface micromachined capaci- tive sensing cell (gcell) and a cmos signal conditioning asic contained in a single integrated circuit package. the sensing element is sealed hermetically at the wafer level using a bulk micromachined acap'' wafer. the gcell is a mechanical structure formed from semicon- ductor materials (polysilicon) using semiconductor pro- cesses (masking and etching). it can be modeled as two stationary plates with a moveable plate inbetween. the center plate can be deflected from its rest position by sub- jecting the system to an acceleration (figure 2). when the center plate deflects, the distance from it to one fixed plate will increase by the same amount that the dis- tance to the other plate decreases. the change in distance is a measure of acceleration. the gcell plates form two backtoback capacitors (figure 3). as the center plate moves with acceleration, the distance between the plates changes and each capacitor's value will change, (c = a e /d). where a is the area of the plate, e is the dielectric constant, and d is the distance between the plates. the cmos asic uses switched capacitor techniques to measure the gcell capacitors and extract the acceleration data from the difference between the two capacitors. the asic also signal conditions and filters (switched capacitor) the signal, providing a high level output voltage that is ratio- metric and proportional to acceleration. acceleration figure 2. transducer physical model figure 3. equivalent circuit model special features filtering the motorola accelerometers contain an onboard 4pole switched capacitor filter. a bessel implementation is used because it provides a maximally flat delay response (linear phase) thus preserving pulse shape integrity. because the fil- ter is realized using switched capacitor techniques, there is no requirement for external passive components (resistors and capacitors) to set the cutoff frequency. selftest the sensor provides a selftest feature that allows the verification of the mechanical and electrical integrity of the accelerometer at any time before or after installation. this feature is critical in applications such as automotive airbag systems where system integrity must be ensured over the life of the vehicle. a fourth aplate'' is used in the gcell as a self test plate. when the user applies a logic high input to the selftest pin, a calibr ated potential is applied across the selftest plate and the moveable plate. the resulting elec- trostatic force (fe = 1 / 2 av 2 /d 2 ) causes the center plate to deflect. the resultant deflection is measured by the accel- erometer's control asic and a proportional output voltage results. this procedure assures that both the mechanical (gcell) and electronic sections of the accelerometer are functioning. ratiometricity ratiometricity simply means that the output offset voltage and sensitivity will scale linearly with applied supply voltage. that is, as you increase supply voltage the sensitivity and offset increase linearly; as supply voltage decreases, offset and sensitivity decrease linearly. this is a key feature when interfacing to a microcontroller or an a/d converter because it provides system level cancellation of supply induced errors in the analog to digital conversion process. status motorola accelerometers include fault detection circuitry and a fault latch. the status pin is an output from the fault latch, or'd with selftest, and is set high whenever one (or more) of the following events occur: ? supply voltage falls below the low voltage detect (lvd) voltage threshold ? clock oscillator falls below the clock monitor minimum frequency ? parity of the eprom bits becomes odd in number. the fault latch can be reset by a rising edge on the self test input pin, unless one (or more) of the fault conditions continues to exist. basic connections 10 11 12 13 14 15 16 8 7 6 5 4 3 2 1 9 n/c n/c n/c st v out n/c v ss v dd n/c n/c n/c n/c n/c n/c n/c n/c pinout description f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
246 motorola sensor device data www.motorola.com/semiconductors pin no. pin name description 1 thru 3 e no internal connection. leave unconnected. 4 st logic input pin used to initiate selftest. 5 v out output voltage of the accelerome- ter. 6 e no internal connection. leave unconnected. 7 v ss the power supply ground. 8 v dd the power supply input. 9 thru 13 trim pins used for factory trim. leave unconnected. 14 thru 16 e no internal connection. leave unconnected. mma2201d st v dd v ss v out output signal r1 1 k w 5 c2 0.01 m f 4 8 7 logic input v dd c1 0.1 m f figure 4. soic accelerometer with recommended connection diagram status 6 pcb layout p0 a/d in v rh v ss v dd st v out v ss v dd 0.01 m f c 1 k w 0.1 m f c 0.1 m f power supply c r c 0.1 m f microcontroller accelerometer figure 5. recommend pcb layout for interfacing accelerometer to microcontroller p1 status notes: ? use a 0.1 m f capacitor on v dd to decouple the power source. ? physical coupling distance of the accelerometer to the microcontroller should be minimal. ? place a ground plane beneath the accelerometer to reduce noise, the ground plane should be attached to all of the open ended terminals shown in figure 4. ? use an rc filter of 1 k w and 0.01 m f on the output of the accelerometer to minimize clock noise (from the switched capacitor filter circuit). ? pcb layout of power and ground should not couple power supply noise. ? accelerometer and microcontroller should not be a high current path. ? a/d sampling rate and any external power supply switching frequency should be selected such that they do not inter- fere with the internal accelerometer sampling frequency. this will prevent aliasing errors. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
247 motorola sensor device data www.motorola.com/semiconductors * when positioned as shown, the earth's gravity will result in a positive 1g output positive acceleration sensing direction 10 11 12 13 14 15 16 8 7 6 5 4 3 2 1 9 n/c n/c n/c self test x out n/c v ss v dd n/c n/c n/c n/c n/c n/c n/c n/c 16pin soic package n/c pins are recommended to be left floating axis orientation (acceleration force vector) x +x 10 11 12 13 14 15 16 87654321 9 direction of earth's gravity field.* ordering information device temperature range case no. package mma2201d 40 to +85 c case 47501 soic16 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
248 motorola sensor device data www.motorola.com/semiconductors
the mma series of silicon capacitive, micromachined accelerometers features signal conditioning, a 4pole low pass filter and temperature compensation. zerog offset full scale span and filter cutoff are factory set and require no external devices. a full system selftest capability verifies system functionality. features ? integral signal conditioning ? linear output ? ratiometric performance ? 4th order bessel filter preserves pulse shape integrity ? calibrated selftest ? low voltage detect, clock monitor, and eprom parity check status ? transducer hermetically sealed at wafer level for superior reliability ? robust design, high shocks survivability typical applications ? vibration monitoring and recording ? impact monitoring ? appliance control ? mechanical bearing monitoring ? computer hard drive protection ? computer mouse and joysticks ? virtual reality input devices ? sports diagnostic devices and systems simplified accelerometer functional block diagram gcell sensor integrator gain filter temp comp selftest control logic & eprom trim circuits clock gen. oscillator v dd v out v ss st figure 1. simplified accelerometer functional block diagram status rev 0 semiconductor technical data mma2202d: x axis sensitivity micromachined accelerometer 50g 16 lead soic case 475 16 9 1 8 10 11 12 13 14 15 16 8 7 6 5 4 3 2 1 9 n/c n/c n/c st v out status v ss v dd n/c n/c n/c n/c n/c n/c n/c n/c pin assignment f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
249 motorola sensor device data www.motorola.com/semiconductors maximum ratings (maximum ratings are the limits to which the device can be exposed without causing permanent damage.) rating symbol value unit powered acceleration (all axes) g pd 500 g unpowered acceleration (all axes) g upd 2000 g supply voltage v dd 0.3 to +7.0 v drop test (1) d drop 1.2 m storage temperature range t stg 40 to +105 c notes: 1. dropped onto concrete surface from any axis. electro static discharge (esd) warning: this device is sensitive to electrostatic discharge. although the motorola accelerometers contain internal 2kv esd protection circuitry, extra precaution must be taken by the user to protect the chip from esd. a charge of over 2000 volts can accumulate on the human body or associated test equipment. a charge of this magnitude can alter the per- formance or cause failure of the chip. when handling the accelerometer, proper esd precautions should be followed to avoid exposing the device to discharges which may be detrimental to its performance. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
250 motorola sensor device data www.motorola.com/semiconductors operating characteristics (unless otherwise noted: 40 c t a +85 c, 4.75 v dd 5.25, acceleration = 0g, loaded output (1) ) characteristic symbol min typ max unit operating range (2) supply voltage (3) supply current operating temperature range acceleration range v dd i dd t a g fs 4.75 4.0 40 e 5.00 5.0 e 47 5.25 6.0 +85 e v ma c g output signal zero g (v dd = 5.0 v) (4) zero g sensitivity (t a = 25 c, v dd = 5.0 v) (5) sensitivity bandwidth response nonlinearity v off v off,v s s v f 3db nl out 2.3 0.44 v dd 37 7.4 360 1.0 2.5 0.50 v dd 40 8 400 e 2.7 0.56 v dd 43 8.6 440 +1.0 v v mv/g mv/g/v hz % fso noise rms (.011 khz) power spectral density clock noise (without rc load on output) (6) n rms n psd n clk e e e e 110 2.0 2.8 e e mvrms m v/(hz 1/2 ) mvpk selftest output response input low input high input loading (7) response time (8) g st v il v ih i in t st 10 v ss 0.7 x v dd 30 e 12 e e 110 2.0 14 0.3 x v dd v dd 300 10 g v v m a ms status (12)(13) output low (i load = 100 m a) output high (i load = 100 m a) v ol v oh e v dd .8 e e 0.4 e v v minimum supply voltage (lvd trip) v lvd 2.7 3.25 4.0 v clock monitor fail detection frequency f min 150 e 400 khz output stage performance electrical saturation recovery time (9) full scale output range (i out = 200 m a) capacitive load drive (10) output impedance t delay v fso c l z o e 0.3 e e 0.2 e e 300 e v dd 0.3 100 e ms v pf w mechanical characteristics transverse sensitivity (11) package resonance v zx,yx f pkg e e e 10 5.0 e % fso khz notes: 1. for a loaded output the measurements are observed after an rc filter consisting of a 1 k w resistor and a 0.01 m f capacitor to ground. 2. these limits define the range of operation for which the part will meet specification. 3. within the supply range of 4.75 and 5.25 volts, the device operates as a fully calibrated linear accelerometer. beyond these supply limits the device may operate as a linear device but is not guaranteed to be in calibration. 4. the device can measure both + and acceleration. with no input acceleration the output is at midsupply. for positive acceleration the output will increase above v dd /2 and for negative acceleration the output will decrease below v dd /2. 5. the device is calibrated at 20g. 6. at clock frequency 70 khz. 7. the digital input pin has an internal pulldown current source to prevent inadvertent self test initiation due to external bo ard level leakages. 8. time for the output to reach 90% of its final value after a selftest is initiated. 9. time for amplifiers to recover after an acceleration signal causing them to saturate. 10. preserves phase margin (60 ) to guarantee output amplifier stability. 11. a measure of the device's ability to reject an acceleration applied 90 from the true axis of sensitivity. 12. the status pin output is not valid following powerup until at least one rising edge has been applied to the selftest pin. the status pin is high whenever the selftest input is high. 13. the status pin output latches high if a low voltage detection or clock frequency failure occurs, or the eprom parity changes to odd. the status pin can be reset by a rising edge on selftest, unless a fault condition continues to exist. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
251 motorola sensor device data www.motorola.com/semiconductors principle of operation the motorola accelerometer is a surfacemicromachined integratedcircuit accelerometer. the device consists of a surface micromachined capaci- tive sensing cell (gcell) and a cmos signal conditioning asic contained in a single integrated circuit package. the sensing element is sealed hermetically at the wafer level using a bulk micromachined acap'' wafer. the gcell is a mechanical structure formed from semicon- ductor materials (polysilicon) using semiconductor pro- cesses (masking and etching). it can be modeled as two stationary plates with a moveable plate inbetween. the center plate can be deflected from its rest position by sub- jecting the system to an acceleration (figure 2). when the center plate deflects, the distance from it to one fixed plate will increase by the same amount that the dis- tance to the other plate decreases. the change in distance is a measure of acceleration. the gcell plates form two backtoback capacitors (figure 3). as the center plate moves with acceleration, the distance between the plates changes and each capacitor's value will change, (c = a e /d). where a is the area of the plate, e is the dielectric constant, and d is the distance between the plates. the cmos asic uses switched capacitor techniques to measure the gcell capacitors and extract the acceleration data from the difference between the two capacitors. the asic also signal conditions and filters (switched capacitor) the signal, providing a high level output voltage that is ratio- metric and proportional to acceleration. acceleration figure 2. transducer physical model figure 3. equivalent circuit model special features filtering the motorola accelerometers contain an onboard 4pole switched capacitor filter. a bessel implementation is used because it provides a maximally flat delay response (linear phase) thus preserving pulse shape integrity. because the fil- ter is realized using switched capacitor techniques, there is no requirement for external passive components (resistors and capacitors) to set the cutoff frequency. selftest the sensor provides a selftest feature that allows the verification of the mechanical and electrical integrity of the accelerometer at any time before or after installation. this feature is critical in applications such as automotive airbag systems where system integrity must be ensured over the life of the vehicle. a fourth aplate'' is used in the gcell as a self test plate. when the user applies a logic high input to the selftest pin, a calibr ated potential is applied across the selftest plate and the moveable plate. the resulting elec- trostatic force (fe = 1 / 2 av 2 /d 2 ) causes the center plate to deflect. the resultant deflection is measured by the accel- erometer's control asic and a proportional output voltage results. this procedure assures that both the mechanical (gcell) and electronic sections of the accelerometer are functioning. ratiometricity ratiometricity simply means that the output offset voltage and sensitivity will scale linearly with applied supply voltage. that is, as you increase supply voltage the sensitivity and offset increase linearly; as supply voltage decreases, offset and sensitivity decrease linearly. this is a key feature when interfacing to a microcontroller or an a/d converter because it provides system level cancellation of supply induced errors in the analog to digital conversion process. status motorola accelerometers include fault detection circuitry and a fault latch. the status pin is an output from the fault latch, or'd with selftest, and is set high whenever one (or more) of the following events occur: ? supply voltage falls below the low voltage detect (lvd) voltage threshold ? clock oscillator falls below the clock monitor minimum frequency ? parity of the eprom bits becomes odd in number. the fault latch can be reset by a rising edge on the self test input pin, unless one (or more) of the fault conditions continues to exist. basic connections 10 11 12 13 14 15 16 8 7 6 5 4 3 2 1 9 n/c n/c n/c st v out status v dd n/c n/c n/c n/c n/c n/c n/c n/c pinout description v ss f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
252 motorola sensor device data www.motorola.com/semiconductors pin no. pin name description 1 thru 3 e no internal connection. leave unconnected. 4 st logic input pin used to initiate selftest. 5 v out output voltage of the accelerome- ter. 6 status logic output pin to indicate fault. 7 v ss the power supply ground. 8 v dd the power supply input. 9 thru 13 trim pins used for factory trim. leave unconnected. 14 thru 16 e no internal connection. leave unconnected. mma2202d st v dd v ss v out output signal r1 1 k w 5 c2 0.01 m f 4 8 7 logic input v dd c1 0.1 m f figure 4. soic accelerometer with recommended connection diagram status 6 pcb layout p0 a/d in v rh v ss v dd st v out v ss v dd 0.01 m f c 1 k w 0.1 m f c 0.1 m f power supply c r c 0.1 m f microcontroller accelerometer figure 5. recommend pcb layout for interfacing accelerometer to microcontroller p1 status notes: ? use a 0.1 m f capacitor on v dd to decouple the power source. ? physical coupling distance of the accelerometer to the microcontroller should be minimal. ? place a ground plane beneath the accelerometer to reduce noise, the ground plane should be attached to all of the open ended terminals shown in figure 4. ? use an rc filter of 1 k w and 0.01 m f on the output of the accelerometer to minimize clock noise (from the switched capacitor filter circuit). ? pcb layout of power and ground should not couple power supply noise. ? accelerometer and microcontroller should not be a high current path. ? a/d sampling rate and any external power supply switching frequency should be selected such that they do not inter- fere with the internal accelerometer sampling frequency. this will prevent aliasing errors. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
253 motorola sensor device data www.motorola.com/semiconductors * when positioned as shown, the earth's gravity will result in a positive 1g output positive acceleration sensing direction 10 11 12 13 14 15 16 8 7 6 5 4 3 2 1 9 16pin soic package n/c pins are recommended to be left floating x +x 10 11 12 13 14 15 16 87654321 9 direction of earth's gravity field.* front view top view side view ordering information device temperature range case no. package mma2202d 40 to +85 c case 47501 soic16 minimum recommended footprint for surface mounted applications surface mount board layout is a critical portion of the total design. the footprint for the surface mount packages must be the correct size to ensure proper solder connection inter- face between the board and the package. with the correct footprint, the packages will selfalign when subjected to a solder reflow process. it is always recommended to design boards with a solder mask layer to avoid bridging and short- ing between solder pads. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
254 motorola sensor device data www.motorola.com/semiconductors figure 6. footprint soic16 (case 47501) 0.380 in. 9.65 mm 0.050 in. 1.27 mm 0.024 in. 0.610 mm 0.080 in. 2.03 mm f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
255 motorola sensor device data www.motorola.com/semiconductors the mma series of silicon capacitive, micromachined accelerometers features signal conditioning, a 4pole low pass filter and temperature compensation. zerog offset full scale span and filter cutoff are factory set and require no external devices. a full system selftest capability verifies system functionality. features ? integral signal conditioning ? linear output ? ratiometric performance ? 4th order bessel filter preserves pulse shape integrity ? calibrated selftest ? low voltage detect, clock monitor, and eprom parity check status ? transducer hermetically sealed at wafer level for superior reliability ? robust design, high shocks survivability typical applications ? vibration monitoring and recording ? impact monitoring ? appliance control ? mechanical bearing monitoring ? computer hard drive protection ? computer mouse and joysticks ? virtual reality input devices ? sports diagnostic devices and systems simplified accelerometer functional block diagram gcell sensor integrator gain filter temp comp selftest control logic & eprom trim circuits clock gen. oscillator v dd x out v ss st figure 1. simplified accelerometer functional block diagram status y out av dd rev 0

semiconductor technical data mma3201d: xy axis sensitivity micromachined accelerometer 40g 20 lead soic case 475a 20 11 1 10 14 15 16 17 18 19 20 8 7 6 5 4 3 2 1 13 n/c n/c n/c st x out status v dd n/c n/c n/c n/c n/c n/c n/c n/c pin assignment 12 10 9 11 v ss av dd n/c y out n/c f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
256 motorola sensor device data www.motorola.com/semiconductors maximum ratings (maximum ratings are the limits to which the device can be exposed without causing permanent damage.) rating symbol value unit powered acceleration (all axes) g pd 200 g unpowered acceleration (all axes) g upd 2000 g supply voltage v dd 0.3 to +7.0 v drop test (1) d drop 1.2 m storage temperature range t stg 40 to +105 c notes: 1. dropped onto concrete surface from any axis. electro static discharge (esd) warning: this device is sensitive to electrostatic discharge. although the motorola accelerometers contain internal 2kv esd protection circuitry, extra precaution must be taken by the user to protect the chip from esd. a charge of over 2000 volts can accumulate on the human body or associated test equipment. a charge of this magnitude can alter the per- formance or cause failure of the chip. when handling the ac- celerometer, proper esd precautions should be followed to avoid exposing the device to discharges which may be detri- mental to its performance. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
257 motorola sensor device data www.motorola.com/semiconductors operating characteristics (unless otherwise noted: 40 c t a +85 c, 4.75 v dd 5.25, x and y channels, acceleration = 0g, loaded output (1) ) characteristic symbol min typ max unit operating range (2) supply voltage (3) supply current operating temperature range acceleration range v dd i dd t a g fs 4.75 6 40 e 5.00 8 e 45 5.25 10 +85 e v ma c g output signal zero g (v dd = 5.0 v) (4) zero g sensitivity (t a = 25 c, v dd = 5.0 v) (5) sensitivity bandwidth response nonlinearity v off v off,v s s v f 3db nl out 2.2 0.44 v dd 45 9 360 1.0 2.5 0.50 v dd 50 10 400 e 2.8 0.56 v dd 55 11 440 +1.0 v v mv/g mv/g/v hz % fso noise rms (.011 khz) power spectral density clock noise (without rc load on output) (6) n rms n psd n clk e e e e 110 2.0 2.8 e e mvrms m v/(hz 1/2 ) mvpk selftest output response input low input high input loading (7) response time (8) g st v il v ih i in t st 9.6 v ss 0.7 x v dd 30 e 12 e e 110 2.0 14.4 0.3 x v dd v dd 300 e g v v m a ms status (12)(13) output low (i load = 100 m a) output high (i load = 100 m a) v ol v oh e v dd .8 e e 0.4 e v v minimum supply voltage (lvd trip) v lvd 2.7 3.25 4.0 v clock monitor fail detection frequency f min 50 e 260 khz output stage performance electrical saturation recovery time (9) full scale output range (i out = 200 m a) capacitive load drive (10) output impedance t delay v fso c l z o e 0.3 e e 0.2 e e 300 e v dd 0.3 100 e ms v pf w mechanical characteristics transverse sensitivity (11) package resonance v zx,yx f pkg e e e 10 5.0 e % fso khz notes: 1. for a loaded output the measurements are observed after an rc filter consisting of a 1 k w resistor and a 0.01 m f capacitor to ground. 2. these limits define the range of operation for which the part will meet specification. 3. within the supply range of 4.75 and 5.25 volts, the device operates as a fully calibrated linear accelerometer. beyond these supply limits the device may operate as a linear device but is not guaranteed to be in calibration. 4. the device can measure both + and acceleration. with no input acceleration the output is at midsupply. for positive acceleration the output will increase above v dd /2 and for negative acceleration the output will decrease below v dd /2. 5. the device is calibrated at 20g. 6. at clock frequency 70 khz. 7. the digital input pin has an internal pulldown current source to prevent inadvertent self test initiation due to external bo ard level leakages. 8. time for the output to reach 90% of its final value after a selftest is initiated. 9. time for amplifiers to recover after an acceleration signal causing them to saturate. 10. preserves phase margin (60 ) to guarantee output amplifier stability. 11. a measure of the device's ability to reject an acceleration applied 90 from the true axis of sensitivity. 12. the status pin output is not valid following powerup until at least one rising edge has been applied to the selftest pin. the status pin is high whenever the selftest input is high. 13. the status pin output latches high if a low voltage detection or clock frequency failure occurs, or the eprom parity changes to odd. the status pin can be reset by a rising edge on selftest, unless a fault condition continues to exist. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
258 motorola sensor device data www.motorola.com/semiconductors principle of operation the motorola accelerometer is a surfacemicromachined integratedcircuit accelerometer. the device consists of a surface micromachined capaci- tive sensing cell (gcell) and a cmos signal conditioning asic contained in a single integrated circuit package. the sensing element is sealed hermetically at the wafer level us- ing a bulk micromachined acap'' wafer. the gcell is a mechanical structure formed from semicon- ductor materials (polysilicon) using semiconductor pro- cesses (masking and etching). it can be modeled as two stationary plates with a moveable plate inbetween. the center plate can be deflected from its rest position by sub- jecting the system to an acceleration (figure 2). when the center plate deflects, the distance from it to one fixed plate will increase by the same amount that the dis- tance to the other plate decreases. the change in distance is a measure of acceleration. the gcell plates form two backtoback capacitors (fig- ure 3). as the center plate moves with acceleration, the dis- tance between the plates changes and each capacitor's value will change, (c = a e /d). where a is the area of the plate, e is the dielectric constant, and d is the distance be- tween the plates. the cmos asic uses switched capacitor techniques to measure the gcell capacitors and extract the acceleration data from the difference between the two capacitors. the asic also signal conditions and filters (switched capacitor) the signal, providing a high level output voltage that is ratio- metric and proportional to acceleration. acceleration figure 2. transducer physical model figure 3. equivalent circuit model special features filtering the motorola accelerometers contain an onboard 4pole switched capacitor filter. a bessel implementation is used because it provides a maximally flat delay response (linear phase) thus preserving pulse shape integrity. because the fil- ter is realized using switched capacitor techniques, there is no requirement for external passive components (resistors and capacitors) to set the cutoff frequency. selftest the sensor provides a selftest feature that allows the ver- ification of the mechanical and electrical integrity of the ac- celerometer at any time before or after installation. this feature is critical in applications such as automotive airbag systems where system integrity must be ensured over the life of the vehicle. a fourth aplate'' is used in the gcell as a self test plate. when the user applies a logic high input to the selftest pin, a calibr ated potential is applied across the selftest plate and the moveable plate. the resulting elec- trostatic force (fe = 1 / 2 av 2 /d 2 ) causes the center plate to deflect. the resultant deflection is measured by the accel- erometer's control asic and a proportional output voltage re- sults. this procedure assures that both the mechanical (gcell) and electronic sections of the accelerometer are functioning. ratiometricity ratiometricity simply means that the output offset voltage and sensitivity will scale linearly with applied supply voltage. that is, as you increase supply voltage the sensitivity and offset increase linearly; as supply voltage decreases, offset and sensitivity decrease linearly. this is a key feature when interfacing to a microcontroller or an a/d converter because it provides system level cancellation of supply induced errors in the analog to digital conversion process. status motorola accelerometers include fault detection circuitry and a fault latch. the status pin is an output from the fault latch, or'd with selftest, and is set high whenever one (or more) of the following events occur: ? supply voltage falls below the low voltage detect (lvd) voltage threshold ? clock oscillator falls below the clock monitor minimum frequency ? parity of the eprom bits becomes odd in number. the fault latch can be reset by a rising edge on the self test input pin, unless one (or more) of the fault conditions continues to exist. basic connections pinout description 14 15 16 17 18 19 20 8 7 6 5 4 3 2 1 13 n/c n/c n/c st x out status v dd n/c n/c n/c n/c n/c n/c n/c n/c 12 10 9 11 v ss av dd n/c y out n/c f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
259 motorola sensor device data www.motorola.com/semiconductors pin no. pin name description 1 thru 3 e redundant vss. leave unconnected. 4 e no internal connection. leave unconnected. 5 st logic input pin used to initiate selftest. 6 x out output voltage of the accelerometer. x direction. 7 status logic output pin to indicate fault. 8 v ss the power supply ground. 9 v dd power supply input. 10 av dd power supply input (analog). 11 y out output voltage of the accelerometer. y direction. 12 thru 16 e used for factory trim. leave unconnected. 17 thru 20 e no internal connection. leave unconnected. 10 x out y out mma3201d st v dd v ss x output signal r1 1 k w c2 0.01 m f 5 9 8 logic input v dd c1 0.1 m f figure 4. soic accelerometer with recommended connection diagram status 7 6 y output signal c3 0.01 m f r2 1 k w av dd 11 pcb layout p0 a/d in v rh v ss v dd st y out v ss v dd 0.01 m f c 1 k w 0.1 m f c 0.1 m f power supply c r c 0.1 m f microcontroller accelerometer figure 5. recommend pcb layout for interfacing accelerometer to microcontroller p1 status a/d in x out r 0.01 m f c 1 k w notes: ? use a 0.1 m f capacitor on v dd to decouple the power source. ? physical coupling distance of the accelerometer to the mi- crocontroller should be minimal. ? place a ground plane beneath the accelerometer to reduce noise, the ground plane should be attached to all of the open ended terminals shown in figure 4. ? use an rc filter of 1 k w and 0.01 m f on the outputs of the accelerometer to minimize clock noise (from the switched capacitor filter circuit). ? pcb layout of power and ground should not couple power supply noise. ? accelerometer and microcontroller should not be a high current path. ? a/d sampling rate and any external power supply switching frequency should be selected such that they do not inter- fere with the internal accelerometer sampling frequency. this will prevent aliasing errors. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
260 motorola sensor device data www.motorola.com/semiconductors * when positioned as shown, the earth's gravity will result in a positive 1g output positive acceleration sensing direction 20pin soic package n/c pins are recommended to be left floating x +x direction of earth's gravity field.* front view top view side view 14 15 16 17 18 19 20 87654321 13 12 10 9 11 14 15 16 17 18 19 20 8 7 6 5 4 3 2 1 13 12 10 9 11 +y y ordering information device temperature range case no. package mma3201d 40 to +85 c case 475a01 soic20 minimum recommended footprint for surface mounted applications f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
261 motorola sensor device data www.motorola.com/semiconductors surface mount board layout is a critical portion of the total design. the footprint for the surface mount packages must be the correct size to ensure proper solder connection inter- face between the board and the package. with the correct footprint, the packages will selfalign when subjected to a solder reflow process. it is always recommended to design boards with a solder mask layer to avoid bridging and short- ing between solder pads. figure 6. footprint soic20 (case 475a01) 0.380 in. 9.65 mm 0.050 in. 1.27 mm 0.024 in. 0.610 mm 0.080 in. 2.03 mm f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
262 motorola sensor device data www.motorola.com/semiconductors by wayne chavez introduction today's low cost accelerometers are highly integrated devices employing features such as signal conditioning, filtering, offset compensation and self test. combining this feature set with economical plastic packaging requires that the signal conditioning circuitry be as small as possible. one approach is to implement sampled data system and switched capacitor techniques as in the motorola accelerometer. as in all sampled data systems, precautions should be taken to avoid signal aliasing errors. this application note describes the motorola accelerometer and how signal aliasing can be introduced and more importantly minimized. background what is aliasing? simply put, aliasing is the effect of sampling a signal at an insufficient rate, thus creating another signal at a frequency that is the difference between the original signal frequency and the sampling rate. a graphical explanation of aliasing is offered in figure 1. in this figure, the upper trace shows a 50 khz sinusoidal waveform. note that when sampled at a 45 khz rate, denoted by the boxes, a sinusoidal pattern is formed. lowpass filtering the sampled points, to create a continuous signal, produces the 5 khz waveform shown in figure 1 (lower). (the phase shift in the lower figure is due to the lowpass filter). aliased signals, like the one in figure 1 (lower) are often unintentionally produced. signal processing techniques are well understood and sampling rates are chosen appropriately (i.e. nyquist criteria). however, the assumption is that the signals of interest are well characterized and have a limited bandwidth. this assumption is not always true, as in the case of wideband noise. figure 1. aliased signals

semiconductor application note rev 1 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
263 motorola sensor device data www.motorola.com/semiconductors given the brief example on how aliasing can occur, how does the accelerometer relate to aliasing? to answer this question, a brief summary on how the accelerometer works is in order. the accelerometer is a two chip acceleration sensing solution. the first chip is the acceleration transducer, termed gcell, constructed by micro electromechanical systems (mems) technology. the gcell is a two capacitor element where the capacitors are in series and share a common center plate. the deflection in the center plate changes the capaci- tance of each capacitor which is measured by the second chip, termed control chip. the control chip performs the signal conditioning (amplifica- tion, filtering, offset level shift) function in the system. this chip measures the gcell output using switched capacitor tech- niques. by the nature of switched cap techniques, the system is a sampled data system operating at sampling frequency f s . the filter is switched capacitor, 4pole bessel implementation with a 3 db frequency of 400 hz. as a sampled data system, the accelerometer is not immune to signal aliasing. however, given the accelerometer's internal filter, aliased signals will only appear in the output passband when input signals are in the range | n ? f s f signal | f bw . where f s is the sampling rate, f signal is the input signal frequency, f bw is the filter bandwidth and n is a positive integer to account for all harmonics. the graphical representation is shown in figure 2. the bounds can be extended beyond f bw to ensure an alias free output. figure 2. input signal frequency range where a signal will be produced in the output passband. keep out zone hz n*f s f bw n*f s n*f s + f bw accelerometer input signals the accelerometer is a ratiometric electromechanical transducer. therefore, the input signals to the device are the acceleration and the input power source. the acceleration input is limited in frequency bandwidth by the geometry of the sensing, packaging, and mounting structures that define the resonant frequency and response. this response is in the range of 10 khz, however, the practical range is less than 600 hz for most mechanical systems. therefore, aliasing an acceleration signal is unlikely. the power input signal is ideally dc. however, depending on the application system architecture, the power supply line can be riddled with high frequency components. for example, dc to dc converters can operate with switching frequencies between 20 khz and 200 khz. this range encompasses the sampling rate of the accelerometer and point to the power source as the culprit in producing aliased signal. demonstration of aliasing under zero acceleration conditions a 100 mv rms signal was injected onto the power supply line of 5.0 vdc. the frequency of the injected signal was tuned in to produce an alias in the accelerometer's passband. figures 3 and 4 show the difference in output when a high frequency signal is not and is present on the v cc pin of the accelerometer. figure 3. normal waveforms (a) (b) (c) 1.0e+0 1.0e1 1.0e3 1.0e2 1.0e4 1.0e5 1.0e6 1.0e7 41.0 41.2 41.4 41.6 41.8 42.0 frequency (khz) v rms v out sampling frequency 1.0e+0 1.0e1 1.0e3 1.0e2 1.0e4 1.0e5 1.0e6 1.0e7 41.0 41.2 41.4 41.6 41.8 42.0 frequency (khz) v rms v cc sampling frequency 1.0e+0 1.0e1 1.0e3 1.0e2 1.0e4 1.0e5 1.0e6 0 200 400 600 800 1000 frequency (hz) v rms v out f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
264 motorola sensor device data www.motorola.com/semiconductors figure 4. aliasing comparison (a) (b) (c) sampling frequency injected signal frequency 1 . 0e + 0 1.0e1 1.0e3 1.0e2 1.0e4 1.0e5 1.0e6 41.0 41.2 41.4 41.6 41.8 42.0 frequency (khz) v rms v out 1.0e+0 1.0e1 1.0e3 1.0e2 1.0e4 1.0e5 1.0e6 1.0e7 41.0 41.2 41.4 41.6 41.8 42.0 frequency (khz) v rms v cc sampling frequency injected signal frequency 1.0e+0 1.0e1 1.0e3 1.0e2 1.0e4 1.0e5 1.0e6 0 200 400 600 800 1000 frequency (hz) v rms v out points to note: ? under clean dc bias, v out and v cc , figures 3a and 3b have a signal component at the sampling rate. this is due to switched capacitor currents coupling through finite power supply source impedances and pcb paracitics. ? the low frequency output spectrum, figure 3c, displays the internal lowpass filter characteristics. (the filter and sam- pling characteristics are sometimes useful in system de- bugging.) ? when an ac component is superimposed onto v cc near the sampling frequency, as shown in figure 4b, the output will contain the original signal plus a mirrored signal about the sampling frequency, shown in figure 4a. signals on the v cc line will appear at the output due to the ratiometric characteristic of the accelerometer and will be one half the amplitude. ? as a result of sampling, the output waveform of figure 4c is produced where the injected high frequency signal has now produced a signal in the passband. ? harmonics of the aliased signal in the pass band are also shown in figure 4c. ? aliased signals in the passband will be amplified versions of the injected signals. this is due to the signal conditioning circuitry in the accelerometer that includes gain. aliasing avoidance keys ? use a linear regulated power source when feasible. linear regulators have excellent power supply rejection offering a stable dc source. ? if using a switching power supply, ensure that the switching frequency is not close to the accelerometer sampling fre- quency or its harmonics. noting that the accelerometer will gain the aliasing signal, it is desirable to keep frequencies at least 4 khz away from the sampling frequency and its harmonics. 4 khz is one decade from the 3 db frequency, therefore any signals will be sufficiently attenuated by the internal 4pole lowpass filter. ? proper bias decoupling will aid in noise reduction from oth- er sources. with dense surface mount pcb assemblies, it is often difficult to place and route decoupling components. however, the accelerometer is not like a typical logic de- vice. a little extra effort on decoupling goes a long way. ? good pcb layout practices should always be followed. proper system grounding is essential. parasitic capaci- tance and inductance could prove to be troublesome, par- ticularly during emc testing. signal harmonics and subharmonics play a significant role in introducing aliased signals. clean layouts minimize the effects of parasitics and thus signal harmonics and subharmonics. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
265 motorola sensor device data www.motorola.com/semiconductors prepared by: c.s. chua sensor application engineering singapore, a/p introduction this application note describes the concept of measuring impact of an object using an accelerometer, microcontroller hardware/software and a liquid crystal display. due to the wide frequency response of the accelerometer from d.c. to 400hz, the device is able to measure both the static acceleration from the earth's gravity and the shock or vibration from an impact. this design uses a 40g accelerometer (motorola p/n: mma2200w) yields a minimum acceleration range of 40g to +40g. mma2200w front view side view pcb 1.0 g + figure 1. orientation of accelerometer
semiconductor application note rev 2 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
266 motorola sensor device data www.motorola.com/semiconductors concept of impact measurement during an impact, the accelerometer will be oriented as shown in figure 1 to measure the deceleration experienced by the object from dc to 400hz. normally, the peak impact pulse is in the order of a few miniseconds. figure 2 shows a typical crash waveform of a toy car having a stiff bumper. peak impact pulse 10 20 30 40 50 60 0 time (ms) deceleration (g) 50 30 40 20 10 10 0 20 30 40 figure 2. typical crash pattern f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
267 motorola sensor device data www.motorola.com/semiconductors hardware description and operation since mma2200w is fully signalconditioned by its internal opamp and temperature compensation, the output of the accelerometer can be directly interfaced with an analogto digital (a/d) converter for digitization. a filter consists of one rc network should be added if the connection between the output of the accelerometer and the a/d converter is a long track or cable. this stray capacitance may change the position of the internal pole which would drive the output amplifier of the accelerometer into oscillation or unstability. in this design, the cutoff frequency is chosen to be 15.9 khz which also acts as an antialias filter for the a/d converter. the 3db frequency can be approximated by the following equation. f 3db 1 2 p rc referring to the schematic, figure 3, the mma2200w accelerometer is connected to port d bit 5 and the output of the amplifier is connected to port d bit 6 of the micro- controller. this port is an input to the onchip 8bit analogto digital (a/d) converter. typically, the accelerometer provides a signal output to the microprocessor of approximately 0.3 vdc at 55g to 4.7 vdc at +55g of acceleration. however, motorola only guarantees the accuracy within 40g range. using the same reference voltage for the a/d converter and accelerom- eter minimizes the number of additional components, but does sacrifice resolution. the resolution is defined by the following: count v out 5 255 the count at 0g = [2.5/5] 255 128 the count at +25g = [3.5/5] 255 179 the count at 25g = [1.5/5] 255 77 therefore the resolution 0.5g/count the output of the accelerometer is ratiometric to the voltage applied to it. the accelerometer and the reference voltages are connected to a common supply; this yields a system that is ratiometric. by nature of this ratiometric system, variations in the voltage of the power supplied to the system will have no effect on the system accuracy. the liquid crystal display (lcd) is directly driven from i/o ports a, b, and c on the microcontroller. the operation of a lcd requires that the data and backplane (bp) pins must be driven by an alternating signal. this function is provided by a software routine that toggles the data and backplane at approximately a 30 hz rate. other than the lcd, one light emitting diode (led) are connected to the pulse length converter (plm) of the microcontroller. this led will lights up for 3 seconds when an impact greater or equal to 7g is detected. the microcontroller section of the system requires certain support hardware to allow it to function. the mc34064p5 provides an undervoltage sense function which is used to reset the microprocessor at system powerup. the 4 mhz crystal provides the external portion of the oscillator function for clocking the microcontroller and provides a stable base for time bases functions, for instance calculation of pulse rate. software description upon powerup the system, the lcd will display cal for approximately 4 seconds. during this period, the output of the accelerometer are sampled and averaged to obtain the zero offset voltage or zero acceleration. this value will be saved in the ram which is used by the equation below to calculate the impact in term of gforce. one point to note is that the accelerometer should remain stationary during the zero calibration. impact [count count offset ] resolution in this software program, the output of the accelerometer is calculated every 650 m s. during an impact, the peak decelera- tion is measured and displayed on the lcd for 3 seconds before resetting it to zero. in the mean time, if a higher impact is detected, the value on the lcd will be updated accordingly. however, when a low g is detected (e.g. 1.0g), the value will not be displayed. instead, more samples will be taken for further averaging to eliminate the random noise and high frequency component. due to the fact that tilting is a low g and low frequency signal, large number of sampling is preferred to avoid unstable display. moreover, the display value is not hold for 3 seconds as in the case of an impact. figure 4 is a flowchart for the program that controls the system. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
268 motorola sensor device data www.motorola.com/semiconductors mc34064 1 3 2 +5.0 v +5.0 v r1 4.7 k input /reset gnd jumper jumper open r5 r7 r6 +5.0 v +5.0 v 22 p c4 22 p c3 4.0 mhz r2 10 m x1 270 r r8 d1 100 c1 100 n c2 +5.0 v 2 3 1 on/off switch 9.0 v battery 10 n c2 0.1 c3 0.1 c1 +5.0 v 2 6 4 5 3 gnd rework 1.0 k bypass v s output selftest gnd output input j1 j2 r3 r4 10 k 10 k 5.0 v regulator mc78l05acp 36 37 34 35 6 7 28 5 40 1 8 31 32 29 30 11 10 9 16 23 22 21 20 19 18 17 12 27 26 25 24 15 14 13 g1 dp1 a1 f1 c1 b1 d1 e1 g2 dp2 a2 f2 c2 b2 d2 e2 g4 f4 a4 b4 c4 d4 e4 l bp bp g3 f3 a3 b3 c3 d3 e3 dp3 49 48 47 46 45 44 43 42 pc1 pc0 pc3 pc2/eclk pc5 pc4 pc6 pc7 20 21 plmb plma 52 51 sclk tdo 2 1 tcmp2 tcmp1 17 10 vdd osc2 14 13 12 11 9 5 4 3 pd1/an1 pd0/an0 pd3/an3 pd2/an2 pd5/an5 pd4/an4 pd6/an6 pd7/an7 pa0 pa1 pa2 pa3 pa4 pa5 pa6 pa7 29 30 27 28 25 26 24 31 pb0 pb1 pb2 pb3 pb4 pb5 pb6 pb7 37 38 35 36 33 34 32 39 vrh vrl 7 8 roi 60 tcap2 23 tcap1 22 osc1 16 /reset 18 /irq 19 +5.0 v mc68hc05b16cfn lcd5657 mma2200w 4 dp 3 dp 2 dp 1 ll ef ga d cb figure 3. impact measurement schematic drawing f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
269 motorola sensor device data www.motorola.com/semiconductors start initialization clear i/o ports display a calo for 4 seconds autozero read accelerometer current value > 2.0 g? is the impact > 7.0 g? activate the buzzer / led is the current value > peak value? is the peak value been display > 3 second? peak value = current value set 3 second for the timer interrupt output peak value to lcd accumulate the data is the number of samples accumulated = 128? output the current value to lcd take the average of the data is the 3 second for the peak value display over? y n y n y n n y y n y n figure 4. main program flowchart f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
270 motorola sensor device data www.motorola.com/semiconductors software source/assembly program code ****************************************************************************** * * * accelerometer demo car version 2.0 * * * * the following code is written for mc68hc705b16 using mmds05 software * * version 1.01 * * casm05 command line assembler version 3.04 * * p & e microcomputer systems, inc. * * * * written by : c.s. chua * * 29 august 1996 * * * * * * copyright motorola electronics pte ltd 1996 * * all rights reserved * * * * this software is the property of motorola electronics pte ltd. * * * * any usage or redistribution of this software without the express * * written consent of motorola is strictly prohibited. * * * * motorola reserves the right to make changes without notice to any * * products herein to improve reliability, function, or design. motorola * * does not assume liability arising out of the application or use of any * * product or circuit described herein, neither does it convey license * * under its patents rights nor the rights of others. motorola products are * * not designed, intended or authorised for use as component in systems * * intended to support or sustain life or for any other application in * * which the failure of the motorola product could create a situation * * a situation where personal injury or death may occur. should the buyer * * shall indemnify and hold motorola products for any such unintended or * * unauthorised application, buyer shall indemnify and hold motorola and * * its officers, employees, subsidiaries, affiliates, and distributors * * harmless against all claims, costs, damages, expenses and reasonable * * attorney fees arising out of, directly or indirectly, any claim of * * personal injury or death associated with such unintended or unauthorised * * use, even if such claim alleges that motorola was negligent regarding * * the design or manufacture of the part. * * * * motorola and the motorola logo are registered trademarks of motorola inc.* * * * motorola inc. is an equal opportunity/affirmative action employer. * * * ****************************************************************************** ****************************************************************************** * * * software description * * * * this software is used to read the output of the accelerometer mma2200w * * and display it to a lcd as gravity force. it ranges from 55g to +55g * * with 0g as zero acceleration or constant velocity. the resolution is * * 0.5g. * * * * the program will read from the accelerometer and hold the maximum * * deceleration value for about 3.0 seconds before resetting. at the same * * time, the buzzer/led is activated if the impact is more than 7.0g. * * however, if the maximum deceleration changes before 3.0 seconds, it * * will update the display using the new value. note that positive value * * implies deceleration whereas negative value implies acceleration * * * ****************************************************************************** ****************************************** * * * initialisation * * * ****************************************** porta equ $00 ; last digit portb equ $01 ; second digit (and negative sign) portc equ $02 ; first digit (and decimal point) addata equ $08 ; adc data adstat equ $09 ; adc status plma equ $0a ; pulse length modulator (output to buzzer) misc equ $0c ; miscellaneous register (slow/fast mode) tcontrol equ $12 ; timer control register tstatus equ $13 ; timer status register ocmphi1 equ $16 ; output compare register 1 high byte f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
271 motorola sensor device data www.motorola.com/semiconductors ocmplo1 equ $17 ; output compare register 1 low byte tcnthi equ $18 ; timer count register high byte tcntlo equ $19 ; timer count register low byte ocmphi2 equ $1e ; output compare register 2 high byte ocmplo2 equ $1f ; output compare register 2 low byte ****************************************** * * * userdefined ram * * * ****************************************** sign equ $54 ; acceleration () or deceleration (+) preshi2 equ $55 ; msb of accumulated acceleration preshi equ $56 preslo equ $57 ; lsb of accumulated acceleration ptemphi equ $58 ; acceleration high byte (temp storage) ptemplo equ $59 ; acceleration low byte (temp storage) acchi equ $5a ; temp storage of acc value (high byte) acclo equ $5b ; (low byte) adcounter equ $5c ; sampling counter average_h equ $5d ; msb of the accumulated data of low g average_m equ $5e average_l equ $5f ; lsb of the accumulated data of low g shift_cnt equ $60 ; counter for shifting the accumulated data ave_cnt1 equ $61 ; number of samples in the accumulated data ave_cnt2 equ $75 temptcnthi equ $62 ; temp storage for timer count register temptcntlo equ $63 ; temp storage for timer count register dechi equ $64 ; decimal digit high byte declo equ $65 ; decimal digit low byte dcoffsethi equ $66 ; dc offset of the output (high byte) dcoffsetlo equ $67 ; dc offset of the output (low byte) maxacc equ $68 ; maximum acceleration temphi equ $69 templo equ $6a temp1 equ $6b ; temporary location for acc during delay temp2 equ $6c ; temporary location for acc during isr div_lo equ $6d ; no of sampling (low byte) div_hi equ $6e ; no of sampling (high byte) no_shift equ $6f ; no of right shift to get average value zero_acc equ $70 ; zero acceleration in no of adc steps hold_cnt equ $71 ; hold time counter hold_done equ $72 ; hold time up flag start_time equ $73 ; start of count down flag rshift equ $74 ; no of shifting required for division org $300 ; rom space 0300 to 3dfe (15,104 bytes) db $fc ; display o0o db $30 ; display o1o db $da ; display o2o db $7a ; display o3o db $36 ; display o4o db $6e ; display o5o db $ee ; display o6o db $38 ; display o7o db $fe ; display o8o db $7e ; display o9o hundredhi db $00 ; high byte of hundreds hundredlo db $64 ; low byte of hundreds tenhi db $00 ; high byte of tens tenlo db $0a ; low byte of tens ****************************************** * * * program starts here upon hard reset * * * ****************************************** reset clr portc ; port c = 0 clr portb ; port b = 0 clr porta ; port a = 0 lda #$ff sta $06 ; port c as output sta $05 ; port b as output sta $04 ; port a as output lda tstatus ; dummy read the timer status register clr ocmphi2 ; so as to clear the ocf clr ocmphi1 lda ocmplo2 jsr comprgt clr start_time f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
272 motorola sensor device data www.motorola.com/semiconductors lda #$40 ; enable the output compare interrupt sta tcontrol cli ; interrupt begins here lda #$cc ; port c = 1100 1100 letter oco sta portc lda #$be ; port b = 1011 1110 letter oao sta portb lda #$c4 ; port a = 1100 0100 letter olo sta porta lda #16 idle jsr dly20 ; idling for a while (16*0.125 = 2 sec) deca ; for the zero offset to stabilize bne idle ; before perform autozero lda #$00 ; sample the data 32,768 times and take sta div_lo ; the average 8000 h = 32,768 lda #$80 ; right shift of 15 equivalent to divide sta div_hi ; by 32,768 lda #!15 ; overall sampling time = 1.033 s) sta no_shift jsr readad ; zero acceleration calibration ldx #5 ; calculate the zero offset lda ptemplo ; dc offset = ptemplo * 5 sta zero_acc mul sta dcoffsetlo ; save the zero offset in the ram txa sta dcoffsethi clr hold_cnt lda #$10 ; sample the data 16 times and take sta div_lo ; the average 0100 h = 16 lda #$00 ; right shift of 4 equivalent to divide sta div_hi ; by 16 lda #$4 ; overall sampling time = 650 us sta no_shift lda zero_acc ; display 0.0g at the start sta maxacc jsr adtolcd clr start_time clr ave_cnt1 clr ave_cnt2 clr shift_cnt clr average_l clr average_m clr average_h repeat jsr readad ; read acceleration from adc lda zero_acc add #$04 cmp ptemplo blo crash ; if the acceleration < 2.0g lda ptemplo ; accumulate the averaged results add average_l ; for 128 times and take the averaging sta average_l ; again to achieve more stable clra ; reading at low g adc average_m sta average_m clra adc average_h sta average_h lda #$01 add ave_cnt1 sta ave_cnt1 clra adc ave_cnt2 sta ave_cnt2 cmp #$04 bne repeat lda ave_cnt1 cmp #$00 bne repeat shifting inc shift_cnt ; take the average of the 128 samples lsr average_h ror average_m ror average_l lda shift_cnt cmp #$0a blo shifting lda average_l f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
273 motorola sensor device data www.motorola.com/semiconductors sta ptemplo lda hold_cnt ; check if the hold time of crash data cmp #$00 ; is up bne noncrash lda ptemplo ; if yes, display the current acceleration sta maxacc ; value jsr adtolcd bra noncrash crash lda zero_acc add #$0e ; if the crash is more than 7g cmp ptemplo ; 7g = 0e h * 0.5 bhs no_inflate lda #$ff ; activate the led sta plma no_inflate jsr maxvalue ; display the peak acceleration jsr adtolcd noncrash clr shift_cnt clr ave_cnt1 clr ave_cnt2 clr average_l clr average_m clr average_h bra repeat ; repeat the whole process ****************************************** * * * delay subroutine * * (162 * 0.7725 ms = 0.125 sec) * * * ****************************************** dly20 sta temp1 lda #!162 ; 1 unit = 0.7725 ms outlp clrx innrlp decx bne innrlp deca bne outlp lda temp1 rts ****************************************** * * * reading the adc data x times * * and take the average * * x is defined by div_hi and div_lo * * * ****************************************** readad lda #$25 sta adstat ; ad status = 25h clr preshi2 clr preshi ; clear the memory clr preslo clrx clr adcounter loop128 txa cmp #$ff beq inc_count bra cont inc_count inc adcounter cont lda adcounter ; if adcounter = x cmp div_hi ; clear bit = 0 beq check_x ; branch to end100 bra endread check_x txa cmp div_lo beq end128 endread brclr 7,adstat,endread ; halt here till ad read is finished lda addata ; read the ad register add preslo ; pres = pres + addata sta preslo clra adc preshi sta preshi clra adc preshi2 sta preshi2 incx ; increase the ad counter by 1 bra loop128 ; branch to loop128 end128 clr rshift ; reset the right shift counter f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
274 motorola sensor device data www.motorola.com/semiconductors divide inc rshift ; increase the right counter lsr preshi2 ror preshi ; right shift the high byte ror preslo ; right shift the low byte lda rshift cmp no_shift ; if the right shift counter >= no_shift bhs enddivide ; end the shifting jmp divide ; otherwise continue the shifting enddivide lda preslo sta ptemplo rts ****************************************** * * * timer service interrupt * * alternates the port data and * * backplane of lcd * * * ****************************************** timercmp sta temp2 ; push accumulator com portc ; port c = (port c) com portb ; port b = (port b) com porta ; port a = (port a) lda start_time ; start to count down the hold time cmp #$ff ; if start_time = ff bne skip_time jsr check_hold skip_time bsr comprgt ; branch to subroutine compare register lda temp2 ; pop accumulator rti ****************************************** * * * check whether the hold time * * of crash impact is due * * * ****************************************** check_hold dec hold_cnt lda hold_cnt cmp #$00 ; is the hold time up? bne not_yet lda #$00 ; if yes, sta plma ; stop buzzer lda #$ff ; set hold_done to ff indicate that the sta hold_done ; hold time is up clr start_time ; stop the counting down of hold time not_yet rts ****************************************** * * * subroutine reset * * the timer compare register * * * ****************************************** comprgt lda tcnthi ; read timer count register sta temptcnthi ; and store it in the ram lda tcntlo sta temptcntlo add #$4c ; add 1d4c h = 7500 periods sta temptcntlo ; with the current timer count lda temptcnthi ; 1 period = 2 us adc #$1d sta temptcnthi ; save the next count to the register sta ocmphi1 lda tstatus ; clear the output compare flag lda temptcntlo ; by access the timer status register sta ocmplo1 ; and then access the output compare rts ; register ****************************************** * * * determine which is the next * * acceleration value to be display * * * ****************************************** maxvalue lda ptemplo cmp maxacc ; compare the current acceleration with bls oldmax ; the memory, branch if it is <= maxacc bra newmax1 oldmax lda hold_done ; decrease the holdtime when cmp #$ff ; the maximum value remain unchanged f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
275 motorola sensor device data www.motorola.com/semiconductors beq newmax1 ; branch if the holdtime is due lda maxacc ; otherwise use the current value bra newmax2 newmax1 lda #$c8 ; hold time = 200 * 15 ms = 3 sec sta hold_cnt ; reload the hold time for the next clr hold_done ; maximum value lda #$ff sta start_time ; start to count down the hold time lda ptemplo ; take the current value as maximum newmax2 sta maxacc rts ****************************************** * * * this subroutine is to convert * * the ad data to the lcd * * save the data to be diaplayed * * in maxacc * * * ****************************************** adtolcd sei ; disable the timer interrupt !! lda #$00 ; load 0000 into the memory sta dechi lda #$00 sta declo lda maxacc ldx #5 mul ; acceleration = ad x 5 add declo ; acceleration is stored as dechi sta declo ; and declo sta acclo ; temporary storage lda #$00 ; assume positive deceleration sta sign ; o00o positive ; o01o negative clra txa adc dechi sta dechi sta acchi ; temporary storage lda declo sub dcoffsetlo ; deceleration = dec dc offset sta declo lda dechi sbc dcoffsethi sta dechi bcs negative ; branch if the result is negative bra search negative lda dcoffsetlo ; acceleration = dc offset dec sub acclo sta declo lda dcoffsethi sbc acchi sta dechi lda #$01 ; assign a negative sign sta sign search clrx ; start the search for hundred digit loop100 lda declo ; acceleration = acceleration 100 sub hundredlo sta declo lda dechi sbc hundredhi sta dechi incx ; x = x + 1 bcc loop100 ; if acceleration >= 100, continue the decx ; loop100, otherwise x = x 1 lda declo ; acceleration = acceleration + 100 add hundredlo sta declo lda dechi adc hundredhi sta dechi txa ; check if the msd is zero and #$ff beq nozero ; if msd is zero, branch to nozero lda $0300,x ; output the first second digit sta portc bra startten nozero lda #$00 ; display blank if msd is zero sta portc f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
276 motorola sensor device data www.motorola.com/semiconductors startten clrx ; start to search for ten digit loop10 lda declo ; acceleration = acceleration 10 sub tenlo sta declo lda dechi sbc tenhi sta dechi incx bcc loop10 ; if acceleration >= 10 continue the decx ; loop, otherwise end lda declo ; acceleration = acceleration + 10 add tenlo sta declo lda dechi adc tenhi sta dechi lda $0300,x ; output the last second digit eor sign ; display the sign sta portb clrx ; start to search for the last digit lda declo ; declo = declo 1 tax lda $0300,x ; output the last digit eor #$01 ; add a decimal point in the display sta porta cli ; enable interrupt again ! rts ****************************************** * * * this subroutine provides services * * for those unintended interrupts * * * ****************************************** swi rti ; software interrupt return irq rti ; hardware interrupt timercap rti ; timer input capture timerrov rti ; timer overflow sci rti ; serial communication interface ; interrupt org $3ff2 ; for 68hc05b16, the vector location fdb sci ; starts at 3ff2 fdb timerrov ; for 68hc05b5, the address starts fdb timercmp ; 1ff2 fdb timercap fdb irq fdb swi fdb reset f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
277 motorola sensor device data www.motorola.com/semiconductors
prepared by: c.s. chua sensor application engineering singapore, a/p introduction in the current design, whenever there is an incoming page, the buzzer will abeepo until any of the buttons is depressed. it can be quite annoying or embarrassing sometime when the button is not within your reach. this application note describes the concept of muting the abeepingo sound by tapping the pager lightly, which could be located in your pocket or hand- bag. this demo board uses an accelerometer, microcontroller hardware/software and a piezo audio transducer. due to the wide frequency response of the accelerometer from d.c. to 400hz, the device is able to measure both the static accelera- tion from the earth's gravity and the shock or vibration from an impact. this design uses a 40g accelerometer (motorola p/n: mma1201p) which yields a minimum acceleration range of 40g to +40g. concept of tap detection to measure the tapping of a pager, the accelerometer must be able to respond in the range of hundreds of hertz. during the tapping of a pager at the top surface, which is illustrated in figure 1, the accelerometer will detect a negative shock level between 15g to 50g of force depending on the intensity. similarly, if the tapping action comes from the bottom of the accelerometer, the output will be a positive value. normally, the peak impact pulse is in the order of a few milliseconds. figure 2 shows a typical waveform of the accelerometer under shock. tapping action front view pcb figure 1. tapping action of accelerometer 0.05 0.03 0.01 0.01 0.03 0.05 70 60 50 40 30 20 10 0 10 20 30 0 time (seconds) accelerometer output (g) tapping of accelerometer figure 2. typical waveform of accelerometer under tapping action therefore, we could set a threshold level, either by hard- ware circuitry or software algorithm, to determine the tapping action and mute the abeepingo. in this design, a hardware solution is used because there will be minimal code added to the existing pager software. however, if a software solution is used, the user will be able to program the desire shock level. hardware description and operation since mma1201p is fully signalconditioned by its internal opamp and temperature compensation, the output of the ac- celerometer can be directly interfaced with a comparator. to simplify the hardware, only one direction (tapping on top of the sensor) is monitored. the comparator is configured in such a way that when the output voltage of the accelerometer is less than the threshold voltage or vref (refer to figure 3), the output of the comparator will give a logic a1o which is illustrated in figure 4. to decrease the vref voltage or increase the threshold impact in magnitude, turn the trimmer r2 anticlockwise. semiconductor application note rev 3 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
278 motorola sensor device data www.motorola.com/semiconductors r1 100 k +5.0 v 4 1 5 6 7 8 3 2 +5.0 v r2 100 k 2 1 c3 1.0 + + u1 lm311n v out v in v ref figure 3. comparator circuitry for instance, if the threshold level is to be set to 20g, this will correspond to a vref voltage of 1.7 v. v ref v offset v g g threshold 2.5 (0.04 [ 20]) 1.7 v under normal condition, vin (which is the output of the accelerometer) is at about 2.5v. since vin is higher than vref, the output of the comparator is at logic a0o. during any shock or impact which is greater than 20g in magnitude, the output voltage of the accelerometer will go below vref. in this case, the output logic of the comparator changes from a0o to a1o. when the pager is in silence mode, the vibrator produces an output of about 2g. this will not trigger the comparator. therefore, even in silence mode, the user can also tap the pager to stop the alert. refer to figure 5 for the vibrator waveform. 0.05 0.03 0.01 0.01 0.03 0.05 0 1.0 2.0 3.0 4.0 5.0 6 . 0 0 time (seconds) v (v) out figure 4. comparator output waveform 0.025 0.015 0.005 0.005 0.015 0.025 2.0 1.5 1.0 0.5 0 1.5 2 . 0 0 time (seconds) vibrator movement (g) 0.5 1.0 figure 5. vibrator waveform f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
279 motorola sensor device data www.motorola.com/semiconductors figure 6 is a schematic drawing of the whole demo and figures 7, 8, and 9 show the printed circuit board and compo- nent layout for the shock and mute pager. table 1 is the corre- sponding part list. osc1 /reset /irq tcap1 tcap2 v rh v rl pa0 pa1 pa2 pa3 pa4 pa5 pa6 pa7 pb0 pb1 pb2 pb3 pb4 pb5 pb6 pb7 pd7/an7 pd6/an6 pd5/an5 pd4/an4 pd3/an3 pd2/an2 pd1/an1 pd0/an0 pc7 pc6 pc5 pc4 pc3 pc2/eclk pc1 pc0 plmb plma v ss sclk tdo tcmp2 tcmp1 v dd osc2 14 13 12 11 9 5 4 3 49 48 47 46 45 44 43 42 20 21 52 51 2 1 17 10 32 33 34 35 36 37 38 39 24 25 26 27 28 29 30 31 7 8 41 23 22 19 18 16 piezo transducer u4 j2 mc78l05acp c10 2 1 u5 2 gnd input output c9 0.1 +5.0 v 0.33 31 v s gnd bypass output selftest c4 22 p +5.0 v c11 47 c6 10 n r4 10 m c3 22 p +5.0 v r5 10 k c5 10 n +5.0 v r6 180 r r7 10 k j1 r8 1.0 k c8 10 n 4 5 mc68hc705b16cfn u3 r9 10 k 6 8 7 c1 0.1 c2 0.1 r3 10 k r1 100 k c7 0.1 +5.0 v 4 1 5 6 7 8 3 2 +5.0 v mma1201p r2 100 k 2 1 c12 1.0 + + u2 lm311n d1 +5.0 v s2 s1 +5.0 v + x1 u1 figure 6. overall schematic diagram of the demo 4 mhz f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
280 motorola sensor device data www.motorola.com/semiconductors figure 7. silk screen of the pcb gnd shock & mute pager r4 r2 c6 c12 r1 r3 u4 c11 r8 u5 r6 s1 c5 c10 r5 c3 c4 x1 d1 9v j2 c9 u1 u2 s2 u3 c7 c8 c2 c1 r9 r7 j1 figure 8. solder side of the pcb table 1. bill of material for the shock and mute pager device type qty. value references ceramic capacitor 4 0.1 m c1, c2, c7, c9 ceramic capacitor 2 22p c3, c4 ceramic capacitor 3 10n c5, c6, c8 solid tantalum 1 0.33 m c10 electrolytic capacitor 1 47 m c11 electrolytic capacitor 1 1 m c12 led 1 5mm d1 header 1 2 way j1 pcb terminal block 1 2 way j2 resistor 5% 0.25w 1 100k r1 single turn trimmer 1 100k r2 resistor 5% 0.25w 4 10k r3, r5, r7, r9 resistor 5% 0.25w 1 10m r4 resistor 5% 0.25w 1 180r r6 resistor 5% 0.25w 1 1k r8 push button 2 6mm s1, s2 mma1201p 1 e u1 lm311n 1 e u2 mc68hc705b16cfn 1 e u3 piezo transducer 1 e u4 mc78l05acp 1 e u5 crystal 1 4mhz x1 figure 9. component side of the pcb software description upon powering up the system, the piezo audio transducer is activated simulating an incoming page, if the pager is in sound mode (jumper j1 in on). then, the accelerometer is powered up and the output of the comparator is sampled to obtain the logic level. the abeepingo will continue until the accelerometer senses an impact greater than the threshold level. only then the alert is muted. however when the pager is in silence mode (jumper j1 is off), which is indicated by the blinking red led, the accelerometer is not activated. to stop the alert, press the pushbutton s2. to repeat the whole process, simply push the reset switch s1. figure 10 is a flowchart for the program that controls the system. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
281 motorola sensor device data www.motorola.com/semiconductors receive a page turn on the shock sensor is it in silence mode? y is shock sensor activated or button activated? turn off the shock sensor turn off the buzzer or vibrator end n n y n is button activated? y figure 10. main program flowchart conclusion the shock and mute pager design uses a comparator to create a logic level output by comparing the accelerometer output voltage and a userdefined reference voltage. the flexibility of this minimal component, high performance design makes it compatible with many different applications, e.g. hard disk drive knock sensing, etc. the design presented here uses a comparator which yields excellent logiclevel outputs and output transition speeds for many applications. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
282 motorola sensor device data www.motorola.com/semiconductors software source/assembly program code ****************************************************************************** * * * pager shock & mute detection version 1.0 * * * * the following code is written for mc68hc705b16 using mmds05 software * * version 1.01 * * casm05 command line assembler version 3.04 * * p & e microcomputer systems, inc. * * * * written by : c.s. chua * * 9th january 1997 * * * * software description * * * * j1 on sound mode * * buzzer will turn off if the accelerometer is tapped or switch s2 is * * depressed. * * * * j1 off silence mode * * led will turn off if and only if s2 is depressed * * * ****************************************************************************** ****************************************** * * * i/o declaration * * * ****************************************** portb equ $01 ; port b plma equ $0a ; d/a to control buzzer tcontrol equ $12 ; timer control register tstatus equ $13 ; timer status register ocmphi1 equ $16 ; output compare register 1 high byte ocmplo1 equ $17 ; output compare register 1 low byte tcnthi equ $18 ; timer count register high byte tcntlo equ $19 ; timer count register low byte ocmphi2 equ $1e ; output compare register 2 high byte ocmplo2 equ $1f ; output compare register 2 low byte ****************************************** * * * ram area ($0050 $0100) * * * ****************************************** org $50 stack rmb 4 ; stack segment temptcntlo rmb 1 ; temp. storage of timer result (lsb) temptcnthi rmb 1 ; temp. storage of timer result (msb) ****************************************** * * * rom area ($0300 $3dfd) * * * ****************************************** org $300 ****************************************** * * * program starts here upon hard reset * * * ****************************************** reset clr portb ; initialise ports lda #%01001000 ; configure port b sta $05 lda tstatus ; dummy read the timer status register so as to clear the ocf clr ocmphi2 clr ocmphi1 lda ocmplo2 jsr comprgt lda #$40 ; enable the output compare interrupt sta tcontrol lda #10 ; idle for a while before obeepingo idle jsr dly20 deca bne idle cli ; interrupt begins here brset 1,portb,silence ; branch if j1 is off bset 6,portb ; turn on accelerometer jsr dly20 ; wait till the supply is stable test brset 5,portb,mute ; sample shock sensor for tapping brclr 7,portb,mute ; sample switch s2 for muting jmp test mute bclr 6,portb ; turn off accelerometer sei clr plma ; turn off buzzer f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
283 motorola sensor device data www.motorola.com/semiconductors done jmp done ; end silence brset 7,portb,silence ; sample switch s2 for stopping led sei bclr 3,portb ; turn off led jmp done ; end ****************************************** * * * timer service interrupt * * alternates the plma data * * and bit 3 of port b * * * ****************************************** timercmp bsr comprgt ; branch to subroutine compare register brset 1,portb,skipbuzzer ; branch if j1 is off lda plma eor #$80 ; alternate the buzzer sta plma rti skipbuzzer brset 3,portb,off_led ; alternate led supply bset 3,portb rti off_led bclr 3,portb rti ****************************************** * * * subroutine reset * * the timer compare register * * * ****************************************** comprgt lda tcnthi ; read timer count register sta temptcnthi ; and store it in the ram lda tcntlo sta temptcntlo add #$50 ; add c350 h = 50,000 periods sta temptcntlo ; with the current timer count lda temptcnthi ; 1 period = 2 us adc #$c3 sta temptcnthi ; save the next count to the register sta ocmphi1 lda tstatus ; clear the output compare flag lda temptcntlo ; by access the timer status register sta ocmplo1 ; and then access the output compare register rts ****************************************** * * * delay subroutine for 0.20 sec * * * * input: none * * output: none * * * ****************************************** dly20 sta stack+2 stx stack+3 lda #!40 ; 1 unit = 0.7725 ms outlp clrx innrlp decx bne innrlp deca bne outlp ldx stack+3 lda stack+2 rts ****************************************** * * * this subroutine provides services * * for those unintended interrupts * * * ****************************************** swi rti ; software interrupt return irq rti ; hardware interrupt timercap rti ; timer input capture timerrov rti ; timer overflow interrupt sci rti ; serial communication interface interrupt org $3ff2 ; for 68hc05b16, the vector location fdb sci ; starts at 3ff2 fdb timerrov ; for 68hc05b5, the address starts at 1ff2 fdb timercmp fdb timercap fdb irq fdb swi fdb reset f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
284 motorola sensor device data www.motorola.com/semiconductors prepared by: carlos miranda systems and applications engineer and gary o'brien new product development engineer introduction silicon micromachined accelerometers designed for a vari- ety of applications including automotive airbag deployment systems must meet stringent performance requirements and still remain low cost. achieving the requisite enhanced func- tionality encompasses overcoming challenges in both trans- ducer micromachining and subsequent signal conditioning. motorola's accelerometer architecture includes two separate elements in a single package to achieve overall functionality: a sensing element (agcello) and a signal conditioning element (acontrol asico). figure 1 shows a functional block diagram of motorola's new mma1201p. the transducer is a surface micromachined differential capacitor with two fixed plates and a third mov- able plate. the movable plate is attached to an inertial mass. when acceleration is applied to the device, the inertial mass is displaced causing a change in capacitance. the second die is a cmos control asic which acts as a capacitance to voltage converter and conditions the signal to provide a high level output. the output signal has an offset voltage nomi- nally equivalent to v dd /2 so that both positive and negative acceleration can be measured. this document describes motorola's new mma1201p accelerometer, which uses a new control asic architecture. it explains important new features that have been incorpo- rated into the asic, and presents an overview of the key performance characteristics of the new accelerometer. the document also details the minimum supporting circuitry needed to operate a motorola accelerometer and interface it to an mcu. finally, the power supply rejection ratio (psrr) characteristics and an aliasing gain model are presented. mma1201p features several design enhancements have been implemented into the new mma1201p. the oscillator circuit, which is the heart of the asic, has been redesigned to improve stability over temperature. a filter has been added to the power supply line for internally generated biases. a new sensing scheme is used to sample the differential capacitor transducer and condition the signal. finally, the temperature compensation stage has been redesigned to be trimmable. a block diagram represen- tation of the new accelerometer, in a 16 pin dip package, is shown in figure 1. for simplicity, the eprom trim and the selftest circuit blocks have been omitted. gcell cmos control asic capacitance to voltage converter trimmable gain stage trimmable switched capacitor filter trimmable temp. comp. output stage vss vdd vout st vdd filter oscillator figure 1. block diagram representing the mma1201p
semiconductor application note rev 2 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
285 motorola sensor device data www.motorola.com/semiconductors ? oscillator the oscillator has been redesigned to center the nominal frequency within the trimming range and to have better temperature compensation. as shown in figure 1, the oscillator controls three switched capacitor circuit sub blocks within the asic, thus having direct impact on their performance. the trimmable oscillator enhances the con- trol of other performance parameters and enables the part to meet tighter specification tolerances. additionally, the placement of the oscillator on the silicon die has changed, contributing to a 50% reduction in the noise of the part. ? power supply filter an internal capacitor has been added between the v dd and v ss pins to provide some decoupling of the power supply. also, a lowpass filter has been added to the circuitry that supplies power to the transducer element and that sets the dc level of the capacitancetovoltage converter stage. the filter response suppresses high frequency noise, but maintains a ratiometric output. ? new sensing scheme the capacitancetovoltage converter employs innovative circuit techniques (at the time of this writing, patents are pending) to improve signal ratiometricity. amplification is achieved using an eprom trimmable gain stage, provid- ing capability for both coarse and fine tuning. as in the previous version of the control asic, the second gain stage is cascaded by a switched capacitor four pole bessel low- pass filter, with a unity gain response and 3 db frequency at 400 hz. ? temperature compensation the final stage in the asic performs temperature com- pensation of gain. thus, the temperature coefficient for sensitivity is set using eprom trim. performance enhancements motorola's new mma1201p accelerometer provides perfor- mance enhancements in a number of areas, including ratio- metric output, signaltonoise ratio, output filter response, and temperature compensation. for complete details, refer to the mma1201p data sheet. ? ratiometric output the offset voltage and the sensitivity of the part are ratio- metric with supply voltage. typical error values are less than 0.5%. ? signal to noise ratio the noise has been reduced by 50% and is specified at 3.5 mv rms maximum. typical values are about 2.0 mv rms . as a result, the signal to noise ratio of the part is about 50 db. ? lowpass filter response the frequency response of the four pole bessel lowpass filter has the 3 db frequency at 400 hz. the tolerance has been narrowed by 60% and is specified at 40 hz. ? temperature compensation the sensitivity is very uniform over temperature, with typi- cal errors of about 1% over the specified temperature range. also, although the spec allows for the equivalent of 5 mv/ c for the temperature coefficient of offset, typical values are actually less than 2 mv/ c, at v dd equal to 5 v. interface considerations with only four active pin connections, motorola's accel- erometers are very easy to use. there are only a few simple considerations to be taken into account to ensure reliable operation and attain the high level of performance that the can part offer. ? power supply power is applied to the accelerometer through the v dd pin. for optimum performance, it is recommended that the part be powered with a voltage regulator such as the motorola mc78l05. an optional 0.1 m f capacitor can be placed on the v dd pin to complement the accelerometer's internal capacitor and provide additional decoupling of the supply. the capacitor should be physically located as close as possible to the accelerometer. ? ground ground is applied through the v ss pin. whenever pos- sible it is recommended that a solid ground plane be used so that the impedance of the ground path is minimized. if this is not possible, it is strongly recommended that a low impedance trace (no additional components should be connected to it) be used to directly connect the v ss pin to the power supply ground. ? selftest the st pin is an active, high logic level input pin that pro- vides a way for the user to verify proper operation of the part. it is pulled down internally. therefore, for normal operation, the user could apply a logic level a0o or leave it unconnected. applying a logic level a1o to the st pin will apply the equivalent of a 25 g acceleration to the trans- ducer, and the user should see a change in the output equivalent to 25 times the part's rated sensitivity. ? output the accelerometer's output is measured at the v out pin. as shown in figure 1, the asic's oscillator controls the switched capacitor lowpass filter, with a nominal operating frequency of 65 khz. as a result, a clock noise component of about 2 mv peak may be present at 65 khz. therefore, it is recommended that the user place a simple rc lowpass filter on the v out pin to reduce the clock noise present in the output signal. recommended values are a 1 k w resistor and a 0.01 m f capacitor. these values produce a filter with a 3 db frequency at about 16 khz, which will not interfere with the response of the internal bessel filter, yet will pro- vide sufficient attenuation (approximately 12 db) of the clock noise. placing a filter on the output is especially recommended for applications where the signal will be fed into a standalone a/d converter, and in cases where the signal will be ampli- fied to a level where the amplified clock noise may begin to contribute significantly to the noise floor of the system. however, if using an mcu or microprocessor in the system, the user may choose to use a software algorithm to digitally filter the signal, instead of using the analog rc filter. this option would have to be evaluated based on the system performance requirements. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
286 motorola sensor device data www.motorola.com/semiconductors ? connection to the a/d on an mcu when using the accelerometer with the analog to digital converter on an mcu, it is important to connect the supply and ground pins of the accelerometer and the v rh and v rl pins of the mcu to the same supply and ground traces, respectively. this will maximize the ratiometricity of the system by avoiding voltage differences that may result from trace impedances. figure 2 shows the recommended supporting circuitry for operating the new accelerometer. part (a) shows the16 pin dip package version, the mma1201p, while part (b) shows the 6 pin wingback package version, the mma2200w. for the mma1201p, pins 1, 2, 3, 6, 14, 15, and 16 have no internal connections, and pins 9 through 13 are used for calibration and trimming in the factory. these pins should all be left un- connected. for the mma2200w, pins 1 and 4, and the wings (supporting pins) should be left unconnected. vss st vdd vout 5 2 63 mma2200w vcc c1 logic input r1 c2 output signal (b) vss st vdd vout 7 4 85 mma1201p vcc c1 0.1 f logic input 1k r1 c2 output signal (a) 0.01 f 0.1 f 1k 0.01 f figure 2. accelerometers with recommended supporting circuitry 11 trim 3 psrr and aliasing gain model although the operational amplifiers in the mma1201p's control asic have a high power supply rejection ratio with a fairly wide bandwidth, because the accelerometer is in reality a sampled analog system using switched capacitor technol- ogy, it is possible that when powered with a switching power supply, noise from the supply will appear in the output signal. this is known as aliasing, the result being a signal with fre- quency equal to the difference between the frequency of the power supply noise and the accelerometer's sampling fre- quency. aliasing gain is defined as the power of the output signal relative to an injected sinusoid on the v dd line powering the accelerometer. typical switching power supplies have operating frequen- cies between 50 and 100 khz. the operating frequency of the accelerometer's switching capacitor circuitry is roughly 65 khz. should the fundamental frequency of the switching power supply, or its harmonics, fall within 400 hz of the asic's fundamental frequency (or its harmonics), then any noise present in the power supply will be aliased into the passband of the accelerometer. as will be explained later in this section, there are several simple ways to avoid aliasing. as shown in figure 1, there are many different signal pro- cessing stages in the asic. as a result, the aliasing gain characteristics of the part are a little bit more complex than explained in the previous paragraph. an analysis was done to characterize the worst case aliasing gain of the accelerome- ter. devices from three production lots were used. the parts were tested at 105 c with 5.25 v on v dd . the gain code was set to the nominal value plus 4 s . thus, the parts had a sensi- tivity that was approximately twice that of standard parts. figure 3, shows a plot of the aliasing gain model that was developed. the model is based on the worst case results; typical parts should perform much better having much lower aliasing gain. the following equation was used to fit the data and generate the model: aliasing gain = 1.6965 + 0.0029 * freq. (khz) + hrc 1 * freq. (khz) + hrc 2 where hrc 1 and hrc 2 are coefficients used in the model. their values vary for each harmonic. figure 4 lists the values of hrc 1 and hrc 2 for the fundamental frequency and the first 5 harmonics. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
287 motorola sensor device data www.motorola.com/semiconductors 0 0 fundamental 1st 2nd 3rd 4th 5th sampling frequency and harmonics aliasing gain (v/v) 0.5 1 1.5 2 2.5 3 3.5 figure 3. worst case aliasing gain model derived from characterization data harmonic freq. (khz) hrc 1 hrc 2 aliasing gain fundamental 65 0.0101 2.1120 0.4242 1st 130 0.0016 1.4881 0.3674 2nd 195 0.0237 4.1572 2.7116 3rd 260 0.0060 0.2919 0.6007 4th 325 0.0098 3.7439 3.2017 5th 390 0.0164 4.3054 0.7361 figure 4. values for worst case aliasing gain model the aliasing gain model can be used to estimate the amount of noise that can be expected on the output due to noise in the switching power supply. as an example, consider a switching power supply operating at 65.05 khz, with peaktopeak noise levels of 10, 6, 3.3, 2.5, 2, and 1.4 mv for the fundamen- tal and the first five harmonics, respectively. assume the worst case scenario, an almost perfect match of power supply fun- damental frequency with the fundamental of the asic and all noise signals in phase. the power supply noise that would be seen at the output due to each harmonic would be calculated as follows: harmonic aliasing gain p.s. noise output noise fundamental 0.4242 10.00 mv 4.24 mv 1st 0.3674 6.00 mv 2.20 mv 2nd 2.7116 3.33 mv 9.04 mv 3rd 0.6007 2.50 mv 1.50 mv 4th 3.2017 2.00 mv 6.40 mv 5th 0.7361 1.40 mv 1.03 mv f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
288 motorola sensor device data www.motorola.com/semiconductors the total output noise would be the sum of the individual components: total output noise = (4.24 + 2.20 + 9.04 + 1.50 + 6.40 + 1.03) mv total output noise = 24.41 mv peaktopeak. if this output signal were fed into an 8 bit a/d converter, referenced to 5 v full scale, the worst case error due to power supply noise would be equivalent to 1 bit count. the error that can occur in the output due to aliasing gain can be avoided very easily. the easiest method is to power the part with a voltage regulator. since the voltage regulator pro- vides a clean, steady supply, the possibility of aliasing is elimi- nated. if the accelerometer is powered with a switching supply, a filter should be placed on the power supply output to elimi- nate the noise of the harmonics. if placing a filter on the switch- ing supply is not feasible, the user must ensure that the operating frequency of the switching power supply is outside the frequency ranges of the peaks shown in figure 3. the plot shown is a superposition of the response of the internal four pole bessel lowpass filter, scaled by the corresponding alias- ing gain for each harmonic. the bessel filter has the 3 db frequency at 400 hz and, being of fourth order, has a very steep rolloff outside the passband, with approximately 80 db of attenuation at 4 khz. if a switching power supply must be used, its operating frequency should be at least 800 hz from the accelerometer's sampling frequency. any switch- ing noise present will be aliased to 800 hz or higher, where the attenuation will be approximately 24 db or lower, thus reduc- ing the power supply induced noise below the part's noise floor. conclusion the mma1201p accelerometer demonstrates motorola's commitment to continuous product improvement. a new oscil- lator lowers the noise in the part and enables tighter control of the 3 db bandwidth of the internal lowpass filter. the supply voltage is routed to the transducer and the dc level reference of the capacitancetovoltage converter stage through a newly added filter, thus reducing the part's susceptibility to power supply noise. the capacitancetovoltage converter stage uses new signal conditioning methods, which virtually eliminate ratiometric errors. the temperature compensation for sensitivity is improved, producing a very flat response over temperature. overall the part offers much enhanced perfor- mance and is simpler to use. equally important, motorola's mma1201p accelerometer has remained very price competi- tive, making it ideal for most applications requiring accelera- tion sensors. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
289 motorola sensor device data www.motorola.com/semiconductors
prepared by: carlos miranda, systems and applications engineer and david heeley, systems and applications mechanical engineer introduction the baseball pitch speedometer, in its simplest form, con- sists of a target with acceleration sensors mounted on it, an mcu to process the sensors' outputs and calculate the ball speed, and a display to show the result. the actual imple- mentation, shown in figure 1, resembles a miniature pitching cage, that can be used for training and/or entertainment. the cage is approximately 6 ft. tall by 3 ft. wide by 6 ft. deep. the upper portion is wrapped in a nylon net to retain the baseballs as they rebound off the target. a natural rubber mat, backed by a shock resistant acrylic plate, serve as the target. accel- erometers, used to sense the ball impact, and buffers, used to drive the signal down the transmission line, are mounted on the back side of the target. the remainder of the electronics is contained in a display box on the top front side of the cage. accelerometers are sensors that measure the accelera- tion exerted on an object. they convert a physical quantity into an electrical output signal. because acceleration is a vector quantity, defined by both magnitude and direction, an accelerometer's output signal typically has an offset voltage and can swing positive and negative relative to the offset, to account for both positive and negative acceleration. an example acceleration profile is shown in figure 2. because acceleration is defined as the rate of change of velocity with respect to time, the integration of acceleration as a function of time will yield a net change in velocity. by digitizing and numerically integrating the output signal of an accelerometer through the use of a microcontroller, the aarea under the curveo could be computed. the result corresponds to the net change in velocity of the object under observation. this is the basic principle behind the baseball pitch speedometer. figure 1. david heeley, mechanical designer of the baseball pitch speedometer demo, tests his skills at sensors expo boston '97. semiconductor application note rev 1 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
290 motorola sensor device data www.motorola.com/semiconductors a b capture window point of impact threshold level system at steady rate oscillations that result as energy is dissipated figure 2. typical crash pattern for the baseball pitch speedometer demo theory of operation when a ball is thrown against the target, the accelerometer senses the impact and produces an analog output signal, proportional to the acceleration measured, resulting in a crash signature. the amplitude and duration of the crash signature is a function of the velocity of the ball. how can this crash signature be correlated to the velocity of the baseball? by making use of the principle of conservation of momentum (see equation 1). the principle of conservation of momentum states that the total momentum within a closed system remains constant. in our case, the system consists of the thrown ball and the target. m ball *v ball,initial + m target *v target,initial = m ball * v ball,final + m target *v target,final eq. 1 when the ball is thrown, it has a momentum equivalent to m ball *v ball,initial . the target initially has zero momentum since it is stationary. when the ball collides with the target, part of the momentum of the ball is transferred to the target, and the target will momentarily experience acceleration, velocity, and some finite, though small, displacement before dissipating the momentum and returning to a rest state. the other portion of momentum is retained by the ball as it bounces off the target, due to the elastic nature of the collision. by measuring the acceleration imparted on the target, its velocity is computed through integration. ideally, if the mass of the ball, the mass of the target, and the final velocity of the ball are known, then the problem could be solved analytically and the initial velocity of the baseball determined. the analysis of the crash phenomenon is, however, actually quite complex. some factors that must be taken into account and that complicate the analysis greatly, are the spring constant and damping coefficient of the target. the target will be displaced during impact because it is anchored to the frame by a thick rubber mat. this action effectively causes the system to have a certain amount of spring. also, though the mat is very dense, it will deform somewhat during impact and will act as shock absorber. in addition, the ball itself also has a spring constant and damping coefficient associated with it, since it bounces off the target and, though not noticeable by the naked eye, will deform during the impact. finally, and of even greater significance, the mass of the ball, the mass of the target, and the final velocity of the ball are neither known nor measured. so how can the system work? f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
291 motorola sensor device data www.motorola.com/semiconductors the baseball pitch speedometer works by exploiting the fact that the final velocity of the target will be, according to eq. 1, linearly proportional to the initial velocity of the thrown ball. therefore, by measuring the acceleration response of the system to various ball velocities, which can be measured by independent means such as a radar gun, the system could be calibrated and a linear model developed. to facilitate the char- acterization and calibration of the system, a pitching machine was used to ensure that the incident ball speed would be repeatable. it also eliminated potential error caused by the variability of location of impact on the target that would inevit- ably result from several manual throws. figure 3 shows a linear regression plot of the response of the system as a func- tion of incident velocity. as is indicated by the plot, just a simple constant of proportionality could be used to correlate the mea- sured acceleration response to the incident velocity of the ball, with fairly accurate results. figure 3. baseball pitch speedometer characterization data 0 102030405060 0 2000 4000 6000 8000 10000 12000 14000 baseball speed as recorded by radar gun (mph) grand total as recorded by mcu y predicted y implementation e hardware the target mat of the baseball pitch speedometer has an area of approximately 9 ft 2 (3 by 3). even though the rubber material used to construct the target is quite dense and heavy, the transmission of an impact is very poor if the ball strikes the target too far from the sensor. therefore, to cover such a relatively large area it is necessary to use at least four devices; one centered in each quadrant of the square target. in addition, a shock resistant plate about a quarter inch thick is mounted behind the rubber mat. these features help make the response of the system more uniform and reduce errors that result from the variability of where the ball strikes the target. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
292 motorola sensor device data www.motorola.com/semiconductors the bulk of the circuit hardware is contained in a display box mounted on the top front side of the cage. since the accel- erometers are physically located far away from the mother board (about 10 feet of wiring), opamps were used to buffer the accelerometers' output and drive the transmission line. the four accelerometer signals are then simultaneously fed into a comparator network and four of the adc inputs on an mc68hc11 microcontroller. the mc68hc11 was selected because it has the capability of converting four a/d channels in one conversion sequence and operates at a higher clock speed. these two features reduce the overall time interval between digitizations of the analog signal (that result from the minimum required time for proper a/d conversion and from software latency) thus allowing a more accurate representa- tion of the acceleration waveform to be captured. the comparator network serves a similar purpose by eliminating the additional software algorithm and execution time that would be required to continually monitor the outputs of all four accelerometers and determine whether impact has occurred or not. by minimizing this delay (some is still present since the output signal must exceed a threshold, and a finite amount of time is required for this) more of the initial and more significant part of the signal is captured. the comparator network employs four lm311's configured to provide an or function, and a single output is fed into an input capture pin on the mcu. a potentiometer and filter capacitor are used to provide a stable reference threshold voltage to the comparator network. the threshold voltage is set as close as possible to the accelerometers' offset voltage to minimize the delay between ball impact and the triggering of the conversion sequence, but enough clearance must be provided to prevent false triggering due to noise. because the comparator network is wired such that any one of the accel- erometer outputs can trigger it, the threshold voltage must be higher than the highest accelerometer offset voltage. hystere- sis is not necessary for the comparator network, because once the mcu goes into the conversion sequence it ignores the input capture pin. the system is powered using a commercially available 9 v supply. a motorola mc7805 voltage regulator is used to pro- vide a steady 5 volt supply for the operation of the mcu, the accelerometers, the comparator network, and the opamp buffers. the 9 v supply is directly connected to the common anode 8segment led displays. each segment can draw as much as 30 ma of current. therefore, to ensure proper opera- tion, the power supply selected to build this circuit should be capable of supplying at least 600 ma. ports b and c on the mcu are used to drive the led displays. each port output pin is connected via a resistor to the base of a bjt, which has the emitter tied to ground. a current limiting resistor is connected between the collector of each bjt and the cathode of the corresponding segment on the display. to minimize the amount of board space consumed by the output driving cir- cuitry, mpq3904s (quad packaged 2n3904s) were selected instead of the standard discrete 2n3904s. the zero bit on port c is connected to a combination bjt and mosfet circuit that drives the ayour speedo and abest speedo led's. the circuit is wired so that the led's toggle, and only one can be on at a time. figure 4 shows a schematic of the circuit used. part (a) shows the accelerometers, the opamps used to buffer the outputs and drive the transmission lines, the comparator net- work and the potentiometer used to set the detection thresh- old. part (b) shows the mcu, with its minimal required supporting circuitry. part (c) shows the voltage regulator, a mapping of the cathodes to the corresponding segments on the led displays, the bjt switch circuitry used to drive the seven segment display leds (although not shown on the schematic, this circuit block is actually repeated 15 times), and finally, the circuitry used to drive the ayour speedo/abest speedo leds. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
293 motorola sensor device data www.motorola.com/semiconductors figure 4a. accelerometers, buffer opamps, and comparator network st accelerometer st st vdd vss vout u1 4 8 7 vcc c1 0.1 f 5 r1 1 k w c5 0.01 f + u5 3 2 4 7 vcc mc33201 6 + u9 2 3 8 vcc vcc r5 10 k w r6 1 k w pa2/ic1 c9 0.01 f pe4/an4 4 1 lm311 7 st st st vdd vss vout u2 4 8 7 vcc c2 0.1 f 5 r2 1 k w c6 0.01 f + u6 3 2 4 7 vcc mc33201 6 + u10 2 3 8 vcc pe5/an5 4 1 lm311 7 st st st vdd vss vout u3 4 8 7 vcc c3 0.1 f 5 r3 1 k w c7 0.01 f + u7 3 2 4 7 vcc mc33201 6 + u11 2 3 8 vcc pe6/an6 4 1 lm311 7 st st st vdd vss vout u4 4 8 7 vcc c4 0.1 f 5 r4 1 k w c8 0.01 f + u8 3 2 4 7 vcc mc33201 6 + u12 2 3 8 vcc pe7/an7 4 1 lm311 7 c10 1 f vcc r7 20 k w accelerometer accelerometer accelerometer f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
294 motorola sensor device data www.motorola.com/semiconductors figure 4b. mc68hc11e9 mcu with supporting circuitry vcc 8 mhz r11 10 m r15 1 k vcc r12 4.7 k r13 4.7 k vcc in rst* mc34164p gnd 1 2 3 u13 c14 18 pf c13 0.1 vcc vcc pa2/ic1 pe7/an7 pe4/an4 pe5/an5 pe6/an6 r14 4.7 k vrl vrh moda/lir* modb/vstby irq* xirq* reset* xtal extal vss vdd pe7/an7 pe6/an6 pe5/an5 pe4/an4 pe3/an3 pe2/an2 pe1/an1 pe0/an0 pd5/ss* pd4/sck pd3/mosi pd2/miso pd1/txd pd0/rxd pc7/ad7 pc6/ad6 pc5/ad5 pc4/ad4 pc3/ad3 pc2/ad2 pc1/ad1 pc0/ad0 stra/as strb/r/w* pb7/a15 pb6/a14 pb5/a13 pb4/a12 pb3/a11 pb2/a10 pb1/a9 pb0/a8 pa7/pai/oc1 pa6/oc2/oc1 pa5/oc3/oc1 pa4/oc4/oc1 pa3/ic4/oc5/oc1 pa2/ic1 pa1/ic2 pa0/ic3 e mc68hc11e9 51 52 3 2 8 7 1 26 50 48 46 44 49 47 45 43 25 24 23 22 21 20 16 15 14 13 12 11 10 9 4 6 35 36 37 38 39 40 41 42 27 28 29 30 31 32 33 34 5 17 18 19 u14 1 c16 c12 4.7 ayour'' / abest'' f g e d c b a f g e d c b a dp 4.7 k r10 r9 200 k r8 4.7 k reset 1 c11 ones digit led display tens digit led display m f m f m f m f w w w w w w w w 18 pf c15 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
295 motorola sensor device data www.motorola.com/semiconductors vin vout mc78l05acp gnd 1 2 3 u15 +9 vdc p.s. vcc b+ 1 c17 c18 gnd p.s. r16 r30 10 k r32 r46 180 b+ from pb or pc 1/8 led display u16u19 mpq3904 r31 10 r47 pb0 vcc r48 1 vcc ayour speed'' abest speed'' 1/4 mpq3094 u20 vn0300l b c d e f g dp m f 1 m f a w w w k 1 w k w k figure 4c. voltage regulator, led segment mapping, and led driving circuitry f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
296 motorola sensor device data www.motorola.com/semiconductors implementation e software the operation of the baseball pitch speedometer is very simple. upon power on reset, the output leds are initialized to display a00o and abest speed.o the analog to digital con- verter is turned on and the offset voltages of the accelerome- ters are measured and stored. finally, all the variables are initialized and the mcu goes into a dormant state, where it will wait for a negative edge input capture pulse to trigger it to begin processing the crash signal. once the input capture flag is set, the mcu will immediately begin the analog to digital conversion sequence. as it digitizes the crash signature, it will calculate the absolute difference between the current value and the stored offset voltage value. it will integrate by summing up all the differences. figure 2 shows a typical crash signature of the baseball pitch speedometer. as illustrated, starting at the point of impact (a), the acceleration will initially ramp up, reaching a maximum, then decrease as the target is displaced. because the target is constrained to the frame structure, the acceleration will continue to decrease until it reaches a minimum (point b), which correspond to the travel stop of the target. it is difficult to determine exactly when point b will occur, because the amplitude and duration of the initial acceleration pulse will vary with ball speed. therefore, the capture window duration is set so that it will encompass most typical crash signatures, while rejecting most of the secondary ripples that result as the energy is dissipated by the system. after integrating the four signals, the results are added together to produce an overall sum. this procedure averages out the individual responses and reduces measurement error due to the variability of where the ball lands on the target. the mcu then divides the grand sum by an empirically predeter- mined constant of proportionality. the result will then go through a binary to bcd conversion algorithm. a lookup table is used to match the bcd numbers to their corresponding 7segment display codes. the calculated speed is displayed on the two digit 8segment displays (one segment corre- sponds to the decimal point), and the ayour speedo led is turned on while the abest speedo led is turned off. after a duration of approximately five seconds, the leds are toggled and stored best speed is redisplayed. the five second delay is used to provide enough time for the user to check his/her speed and also to allow the target to return to a rest state. the system is now ready for another pitch. a complete listing of the software is presented in the appendix. conclusion the baseball pitch speedometer works fairly well, with an accuracy of +/ 5 mph. the dynamic range of the system is also worthy of note, measuring speeds from less than 10 mph up to well above the 70 mph range. one key point to empha- size, is that the system is empirically calibrated, and so to maintain good accuracy the system should only be used with balls of mass equal to those used during calibration. although intended mainly for training and recreational pur- poses, the baseball pitch speedometer demonstrates a very important concept concerning the use of accelerometers. accelerometers can be used not only to detect that an event such as impact or motion has occurred, but more importantly they measure the intensity of such events. they can be used to discern between different crash levels and durations. this is very useful in applications where it is desired to have the system respond in accord with the magnitude of the input being monitored. an example application would be a smart air bag system, where the speed at which the bag inflates is proportional to the severity of the crash. the deployment rate of the airbag would be controlled so that it does not throw the occupant back against the seat, thus minimizing the possibil- ity of injury to the occupant. another application where this concept may be utilized is in car alarms, where the response may range from an increased state of readiness and monitor- ing, to a full alarm sequence depending on the intensity of the shock sensed by the accelerometer. this could be used to prevent unnecessary firing of the alarm in the event that an animal or person were to inadvertently bump or brush against the automobile. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
297 motorola sensor device data www.motorola.com/semiconductors appendix e assembly code listing for baseball pitch speedometer * baseball pitch speedometer rev. 1.0 * * program waits for detection of impact via the input capture pin and then reads four a/d channels. * the area under the acceleration vs. time curve is found by subtracting the steady state offsets * from the digitized readings and summing the results. the sum is then divided by an empirically * determined constant of proportionality, and the speed of the ball is displayed. * * written by carlos miranda * systems and applications * sensor products division * motorola semiconductor products sector * may 6, 1997 * * ******************************************************************************************************** * although the information contained herein, as well as any information provided relative * * thereto, has been carefully reviewed and is believed accurate, motorola assumes no * * liability arising out of its application or use, neither does it convey any license under * * its patent rights nor the rights of others. * ******************************************************************************************************** * these equates assign memory addresses to variables. eeprom equ $b600 codebgn equ $b60d regoff equ $1000 ;offset to access registers beyond direct addressing range. portc equ $03 portb equ $04 ddrc equ $07 tctl2 equ $21 tflg1 equ $23 adctl equ $30 adr1 equ $31 adr2 equ $32 adr3 equ $33 adr4 equ $34 option equ $39 stack equ $01ff ;starting address for the stack pointer. ram equ $0000 * these equates assign specific masks to variables to facilitate bit setting, clearing, etc. adpu equ $80 ;power up the analog to digital converter circuitry. csel equ $40 ;select the internal system clock. ccf equ $80 ;conversion complete flag. ic1f equ $04 ;input capture 1 flag. ic1fle equ $20 ;configure input capture 1 to detect falling edges only. ic1fclr equ $fb ;clear the input capture 1 flag. chnls47 equ $14 ;select channels 4 through 7 with mult option on. samples equ $0200 ;number of a/d samples taken. oc1f equ $80 ;output compare 1 flag. oc1fclr equ $7f ;clear the output compare flag. curdly equ $0098 ;timer cycles to create delay for displaying oyour speed.o rambyts equ $19 ;number of ram variables to clear during initialization. allones equ $ff yourspd equ $01 prpfctr equ $00ad ;this constant of proportionality was empirically determined. * variables used for computation. org ram offset1 rmb 1 ;one for each accelerometer. offset2 rmb 1 offset3 rmb 1 offset4 rmb 1 sum1 rmb 2 ;area under the acceleration vs. time curve. sum2 rmb 2 sum3 rmb 2 sum4 rmb 2 grndsum rmb 2 count rmb 2 curbin rmb 1 tempbin rmb 1 bcd rmb 2 curdspl rmb 2 maxbin rmb 1 maxdspl rmb 2 * led seven segment display patterns table. org eeprom jmp start sevseg fcb %11111010 fcb %01100000 fcb %11011100 fcb %11110100 fcb %01100110 fcb %10110110 fcb %10111110 fcb %11100000 fcb %11111110 fcb %11100110 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
298 motorola sensor device data www.motorola.com/semiconductors * this is the main program loop. org codebgn start lds #stack ldx #regoff jsr ledinit jsr adcinit jsr varinit main jsr capture jsr compute jsr bintbcd jsr output bra main * this subroutine initializes ports b & c, and the led display. ledinit pshx psha ldx #regoff bset ddrc,x,allones ;configure port c as an output. ldaa sevseg staa portb,x staa portc,x pula pulx rts * this subroutine initializes the analog to digital converter. adcinit pshx psha ldx #regoff bset option,x,adpu ;turn on a/d converter via adpu bit. bclr option,x,csel ;select system e clock via csel bit. clra delay inca bne delay pula pulx rts * this subroutine clears all the memory variables. varinit pshx ldx #$0000 clrvar clr offset1,x inx cpx #rambyts ;number of rmb bytes. blo clrvar doneclr ldx #regoff ldaa #chnls47 ;measure the offset. staa adctl,x ofswait brclr adctl,x,ccf,ofswait ldd adr1,x std offset1 ldd adr3,x std offset3 pulx rts * this subroutine waits for impact and computes the area under the curve. capture pshx psha pshb ldx #regoff bset tctl2,x,ic1fle ;set ic1 to detect falling edge only. bclr tflg1,x,ic1fclr monitor brclr tflg1,x,ic1f,monitor adcread ldaa #chnls47 ;select channels 4 7 for conversion. staa adctl,x adcwait brclr adctl,x,ccf,adcwait caldlt1 ldab adr1,x subb offset1 bpl addsum1 comb incb addsum1 clra addd sum1 std sum1 caldlt2 ldab adr2,x subb offset2 bpl addsum2 comb incb addsum2 clra addd sum2 std sum2 caldlt3 ldab adr3,x subb offset3 bpl addsum3 comb incb f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
299 motorola sensor device data www.motorola.com/semiconductors addsum3 clra addd sum3 std sum3 caldlt4 ldab adr4,x subb offset4 bpl addsum4 comb incb addsum4 clra addd sum4 std sum4 ldd count addd #$0001 std count cpd #samples blo adcread pulb pula pulx rts * this subroutine computes the ball speed by dividing the overall sum by a constant. compute pshx psha pshb ldd sum1 addd sum2 addd sum3 addd sum4 std grndsum ldx #prpfctr idiv xgdx stab curbin pulb pula pulx rts * this subroutine converts from binary to bcd. (limited to number up to 99 decimal.) bintbcd pshx psha pshb ldx #$0000 ldaa curbin staa tempbin clra clrb binshft lsl tempbin rolb lsla cmpb #$10 blo chkdone inca andb #$0f chkdone inx cpx #$0008 beq railat9 chkfive cmpb #$05 blo binshft addb #$03 bra binshft railat9 cmpa #$09 ;force the display to a99o if speed > 100 mph. bls done ldd #$0909 done std bcd ldx #sevseg ;this part finds the seven segment display codes. xgdx addb bcd xgdx ldaa $00,x staa curdspl ldx #sevseg xgdx addb bcd+1 xgdx ldaa $00,x staa curdspl+1 pulb pula pulx rts * this subroutine displays the current speed for 5 seconds & then displays the maximum. output pshx psha pshb f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
2100 motorola sensor device data www.motorola.com/semiconductors ldx #regoff ldaa curbin cmpa maxbin bls oldmax staa maxbin ldd curdspl std maxdspl oldmax ldd curdspl std portc,x bset portb,x,yourspd ;toggle the oyouro/abesto leds. ldd #$0000 ledwait bclr tflg1,x,oc1fclr ;clear output compare 1 flag. dspldly brclr tflg1,x,oc1f,dspldly addd #$0001 cpd #curdly ;decimal 152. (152 * 33ms = 5.0 sec) blo ledwait ldx #$0000 reclear clr sum1,x ;clear 12 ram bytes beginning at address osum1o. inx ;clears sum1 thru sum4, grndsum, and count. cpx #$000c blo reclear ldx #regoff ldd maxdspl std portc,x ;the oyouro/abesto leds are automatically toggled. pulb pula pulx rts f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
2101 motorola sensor device data www.motorola.com/semiconductors prepared by brandon loggins automobile manufacturers require all system electronics to pass stringent electromagnetic compatibility (emc) tests. airbag systems are one of the systems that must perform adequately under emc tests. there are different types of tests for emc, one of which is testing the tolerance of the system to high frequency conducted emissions. one of the most stringent methods for emc evaluation is the bulk current injection (bci) test. the entire airbag system must continue to function normally throughout the bci test. this application note will discuss how to reduce susceptibility to bci for the motorola accelerometer but the information presented here can be applied to other electronic components in the system. bci test setup the bci test procedure follows a published sae engineering standard, aimmunity to radiated electric fields ~ bulk current injection (bci)o, or sae j 1113/401. for an airbag module, this involves injecting the desired current into the wiring harness by controlling current in the injection probe. the test frequency can vary from one to several hundred mhz. there are at least 20 frequency steps per octave required for the test, but as many as 50 steps per octave can be used. the injection probe is placed on the harness in one of three distances from the airbag module connector: 120, 450 and 750 mm. there is a monitor pickup probe present to measure the amount of current being injected. it is placed 50 mm from the airbag module. this feeds back to the system to ensure that the desired test current is being injected on to the wiring harness. figure 1 shows the setup for the bci test. (for more details, see the sae j 1113/401 test procedure). figure 1. bci test setup anechoic chamber wall pc load box injection probe pickup probe wiring harness airbag module 70, 450, or 750 mm 50 mm baseplate connected to ground the harness connects the airbag module to a load box. this load box provides simulated loads for terminating the remainder of the airbag system (firing ignitors, etc.). the data coming back is translated from j1850 to rs232 to be communicated to a dummy terminal on a pc. for safety reasons, this test is typically performed inside an anechoic chamber to shield high frequency emissions from equipment and humans. bci test procedure for the mma2202d accelerometer the accelerometer is evaluated in the following manner. in an airbag system, the microcontroller's a/d converter digitizes the accelerometer output. the microcontroller sends this value to the communication asic which translates the logic from board level logic to rs232, then sends the value back
semiconductor application note rev 2 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
2102 motorola sensor device data www.motorola.com/semiconductors along the wiring harness. once through the chamber wall, the data is translated to rs232 and fed to a dummy terminal. on the terminal screen, the a/d codes for the accelerometer can be monitored for unexpected performance. ideally, when the accelerometer is at rest (no acceleration applied), the output should be at 0 g , regardless of what emc testing the system may be subjected to. depending on the crash algorithm of the airbag module software, there is some allowable offset shift that can be tolerated. higher shift in output could create errors in the crash analysis software, perhaps causing the airbags to unnecessarily deploy when there is not a crash or not deploy when there is a crash. the motorola accelerometer must be able to meet the airbag system requirements throughout bci exposure. it has a sensitivity of 40 mv/g and an offset (0 g output) of 2.50 v. during the bci test, the accelerometer output should be 2.50 v at 0 g with as little drift as possible. a typical airbag system may have software that can tolerate from as little as 0.5 g up to 2.0 g . of deviation from the offset. the system would then expect the accelerometer output to be within 40 mv of the offset during the entire bci test. therefore, at any given frequency of the bci test, if the output deviates outside this expected window of drift, it fails the test. mma2202d accelerometer bci test results if a system has not been well designed for electromagnetic compatibility, the accelerometer, as well as other devices, can have performance problems. what has been found for the accelerometer is that in some system applications, it suffers from an offset shift when certain frequencies of bci are applied. for example, in one airbag system being tested at a certain frequency, with the desired bci current applied, the offset is found to shift down by 60 mv. this would equate to an error of 1.5 g . see figure 2. at other frequencies, this shift is even higher. this dc shift plot was taken with an oscilloscope using a 20 mhz filter to remove the high frequency component of the signal. probes are placed at the accelerometer in the system application. the plot shows the accelerometer output before and after bci was applied (before and after the rf generator creating the high frequency signal was turned on). figure 2. accelerometer tested under high frequency bci accelerometer v out w/o bci accelerometer v out w/bci v cc this phenomenon has been determined to be system level related. pcb layout and grounding for the accelerometer will affect its performance. this was found by testing the accelerometer outside of the airbag module. the device was put on a test board by itself with only the supply decoupling capacitor of 0.1 m f connected to it. to simulate the effect of bci on vcc, a frequency generator was used to inject a known high frequency sinusoid that caused bci failure on to the 5.0 v supply voltage. the device was first tested in small test board with ground provided by one wire back to the supply. this grounding reproduced the failure due to bci seen at the module level. the test board was then mounted down to a ground plane provided by a copper plate and the accelerometer ground was soldered to the plate (providing a low impedance path to ground). with this setup, the offset shift did not occur. if a system does not incorporate a good pcb layout providing a low impedance to ground, the accelerometer output may shift at certain high frequencies. this output offset shift was caused by a shift in the 05 v supply window. because the accelerometer has a ratiometric output, its offset is dependent on the supply voltage. any change in the supply f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
2103 motorola sensor device data www.motorola.com/semiconductors voltage will result in the same proportional change in the output. for example, if the 5 v supply were to change by 10%, from 5.0 v to 5.5 v, the accelerometer offset will change by 10% also, from 2.5 v to 2.75 v. this phenomena would also occur if the ground were to shift. a 100 mv change in ground would result in a 50 mv change in the output. if the accelerometer does not have low impedance path to ground and parasitics from a poor ground are present as a result, the ground seen by the accelerometer may change over frequency. so, during a bci test, if the 5.0 v supply does not shift but the output of the accelerometer does, the ground to the accelerometer may be moving. it was found with some experimentation that the offset shift can be eliminated with proper board layout techniques as described below. proper layout techniques since the motorola accelerometer is a sensitive analog device that relies on a clean supply to function within established parameters, there are some techniques that can be employed to minimize the effects of bci on the accelerometer performance. pcb layout is paramount to reducing susceptibility to bci. ? a low impedance path to ground will provide shunting of the high frequency interference and minimize its effect on the accelerometer. the best way to provide a good path is by putting a solid, unbroken ground plane in the pcb. this ground plane should be shunted to chassis ground at the module connector. this will ensure that the high frequency bci will be shunted before interfering with accelerometer performance. ? all accelerometer pins that require ground connection should be tied together to a common ground. ? traces attached directly to the connector pins can receive high rf noise, which can couple to nearby traces and com- ponents. increasing series impedance of the traces helps reduce the couple or conducted noise. high frequency fil- ters on the supply line and other susceptible lines may be required to filter out high frequency interference introduced by the bci test. signal lines that carry low current can toler- ate series resistances of 100200 w . ? decoupling capacitors on every input line to the common ground plane will help shunt the high frequency away from the system. these should be placed near the connector. ? signal trace lengths to and from the accelerometer should be kept at a minimum. the shorter the trace, the less chance it has of picking up high frequency bci signals as it crosses the board. trace lengths can be reduced by plac- ing the accelerometer and the microcontroller as close together as possible. signal and ground traces looping should be minimized. ? a decoupling capacitor on the accelerometer vcc pin will also help minimize bci effects. the recommended value is 0.1 m f. this capacitor should be placed as close as pos- sible to the accelerometer to achieve the best results. ? to maximize ratiometricity, the accelerometer vcc and the microcontroller a/d reference pin should be on the same trace. the accelerometer ground and the microcontroller ground should also share the same ground point. there- fore, when there is signal interference due to bci, the a/d converter and the accelerometer will see the interference at the same level. this will result in the same digital code representation of acceleration without signal interference. ? a clean power supply to both the accelerometer and the microcontroller should be provided. supply traces should avoid high current traces that might carry high rf currents during the bci test. the traces should be as short as possible. ? the accelerometer should be placed on the opposite end of the pcb away from the connector. the farther the dis- tance, the lower the chance high frequency rf from bci will interfere with the accelerometer. ? the accelerometer should be placed away from high cur- rent paths that may carry high rf currents during the bci test. automotive customers will continue to require airbag systems to have high standards for emc. one way to test for emc is perform the bulk current injection test. because of the high current involved, bci is one of the most difficult emc tests to pass. being part of the airbag system, the accelerometer must continue to function normally under application of high frequency bci. the accelerometer is highly sensitive to placement on the board and its connection to ground. poor design will caused the device to fail the bci test. the practice of good pcb layout, device placement and good grounding will allow the accelerometer to function within specification and pass the bci test. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
2104 motorola sensor device data www.motorola.com/semiconductors
prepared by: leticia gomez and raul figueroa sensor products division systems and applications engineering introduction this application note describes the motorola accelerometer evaluation board (figure 1). the accelerometer evaluation board is a small circuit board intended to serve as an aid in system design with the capability for mounting the following devices: mma1220d, mma1201p, mma1200d, mma2201d. this evaluation board is useful for quickly evaluating any of these three devices. it also provides a means for understanding the best mounting position and location of an accelerometer in your product. circuit description figure 2 is a circuit schematic of the evaluation board. the recommended decoupling capacitor at the power source and recommended rc filter at the output, are included on the evaluation board. this rc filter at the output of the accelerometer minimizes clock noise that may be present from the switched capacitor filter circuit. no additional components are necessary to use the evaluation board. refer to the respective datasheet of the device being used for specifications and technical operation of the accelerometer. the evaluation board has a 4pin header ( j1 in figure 1) for interfacing to a 5 volt power source or a 9 to 15 volt power source (for example, 9 v battery). jumper jp1 (see figure 1) must have the following placement: on ps if a 5 v supply is being used or on batt if a 9 v to 15 v supply is used. a 5 v regulator ( u1 in figure 1) supplies the necessary power for the accelerometer in the batt option. the power header also provides a means for connecting to the accelerometer analog output through a wire to another breadboard or system. four throughhole sockets are included to allow access to the following signals: v dd , gnd, st and status. these sockets can be used as test points or as means for connecting to other hardware. the on/off switch ( s1 ) provides power to the accelerometer and helps preserve battery life if a battery is being used as the power source. s1 must be set towards the aono position for the accelerometer to function. the green led (d1) is lit when power is supplied to the accelerometer. a selftest pushbutton ( s2 ) on the evaluation board is a selftest feature that provides verification of the mechanical and electrical integrity of the accelerometer. the status pin is an output from the fault latch and is set high if one of the fault conditions exists. a second pressing of the pushbutton ( s2 ) resets the fault latch, unless of course one or more fault conditions continue to exist. figure 1. motorola accelerometer evaluation board jumper (jp1) 5 v regulator power header on/off switch (s1) power led (d1) test points selftest pushbutton (s2) mma device mounting hole (1 of 4) (u1) ps batt status (j1) accelerometer output (vout)
semiconductor application note rev 0 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
2105 motorola sensor device data www.motorola.com/semiconductors figure 2. evaluation board circuit schematic .01 f c3 .01 f c4 .1 f c1 9 v to 15 v j1 3 mc78l05 in out gnd 1 .33 f c2 batt +5 v j1 750 r1 ps jp1 on s1 d1 green led v dd status v ss 7 6 status tp2 v out 5 mma1220d st s2 1k r2 4 j1 v out tp3 off 8 2 v dd v dd v out figure 3. motorola accelerometer evaluation board with test socket pin 1 20pin test socket mma device bottom lid snap unused pins soic the board allows for direct mounting of a 16pin dip or soic package. for the soic device, a 20pin test socket is used to allow for evaluation of more than one device without soldering directly to the board and potentially damaging the pcb. care must be taken in placing the device correctly in the socket as four pins of the socket will not be used. with the board oriented as shown in figure 3, pin 1 should face downward and the device should be positioned toward the top of the test socket, thereby exposing the bottom four pins of the test socket. the socket is marked to help identify the 4 unused socket pins. lids to secure the device in the socket are included with the board and delicately snap into place. the lids can be removed by applying pressure to the sides of the lid or by lifting the top and bottom snaps of the lid. pin out description pin name description 4 st logic input pin to initiate selftest 5 v out output voltage of the accelerometer 6 status logic output pin to indicate fault 7 v ss power supply ground 8 v dd power supply input f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
2106 motorola sensor device data www.motorola.com/semiconductors board layout and content figures 4 and 5 show the layout used on the evaluation board. throughhole mounting components have been selected to facilitate component replacement. mounting considerations system design and sensor mounting can affect the response of a sensor system. the placement of the sensor itself is critical to obtaining the desired measurements. it is important that the sensor be mounted as rigidly as possible to obtain accurate results. since the thickness and mounting of the board varies, parasitic resonance may distort the sensor measurement. hence, it is vital to fasten and secure to the largest mass structure of the system, i.e. the largest truss, the largest mass, the point closest to source of vibration. on the other hand, dampening of the sensor device can absorb much of the vibration and give false readings as well. the evaluation board has holes on the four corners of the board for mounting. it is important to maintain a secure mounting scheme to capture the true motion. orientation of the sensor is also crucial. for best results, align the sensitive axis of the accelerometer to the axis of vibration. in the case of the mma1220d, the sensitive axis is perpendicular to the plane of the evaluation board. summary the accelerometer evaluation board is a designin tool for customers seeking to quickly evaluate an accelerometer in terms of output signal, device orientation, and mounting considerations. both throughhole and surface mount packages can be evaluated. with the battery supply option and corner perforations, the board can easily be mounted on the end product; such as a motor or a piece of equipment. easy access to the main pins allows for effortless interfacing to a microcontroller or other system electronics. the simplicity of this evaluation board provides reduced development time and assists in selecting the best accelerometer for the application. fi g ure 4. board la y out ( com p onent side ) fi g ure 5. board la y out ( back side ) f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
2107 motorola sensor device data www.motorola.com/semiconductors case outlines case 47501 issue b 16 lead soic notes: 1. all dimensions are in millimeters. 2. interpret dimensions and tolerances per asme y14.5m, 1994. 3. dimensions oao and obo do not include mold flash or protrusions. mold flash or protrusions shall not exceed 0.15 per side. 4. dimension odo does not include dambar protrusion. protrusions shall not cause the lead width to exceed 0.75 dim min max millimeters a 10.15 10.45 b 7.40 7.60 c 3.30 3.55 d 0.35 0.49 f 0.76 1.14 g 1.27 bsc j 0.25 0.32 k 0.10 0.25 m 0 7 p 10.16 10.67 r 0.25 0.75 18 16 9 p 2 places, 16 tips d 16x a 0.15 b t a m 0.13 b t c k r x 45 j f m seating plane a b a b t g g/2 0.1 case 475a01 issue o 20 lead soic notes: 1. dimensioning and tolerancing per ansi y14.5m, 1982. 2. controlling dimension: millimeter. 3. dimensions a and b do not include mold protrusion. 4. maximum mold protrusion 0.15 (0.006) per side. 5. dimension d does not include dambar protrusion. allowable dambar protrusion shall be 0.13 (0.005) total in excess of d dimension at maximum material condition. dim min max min max inches millimeters a 12.67 12.96 0.499 0.510 b 7.40 7.60 0.292 0.299 c 3.30 3.55 0.130 0.140 d 0.35 0.49 0.014 0.019 f 0.76 1.14 0.030 0.045 g 1.27 bsc 0.050 bsc j 0.25 0.32 0.010 0.012 k 0.10 0.25 0.004 0.009 m 0 7 0 7 p 10.16 10.67 0.400 0.420 r 0.25 0.75 0.010 0.029 110 20 11 t b a p 10 pl d 16 pl m a m 0.13 (0.005) b m t m a m 0.13 (0.005) b m t c k g r x 45 j f m seating plane f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
2108 motorola sensor device data www.motorola.com/semiconductors case 45606 issue j wb package dim min max inches a 0.638 0.618 b 0.260 0.240 c 0.133 0.127 d 0.021 0.015 g 0.100 bsc h 0.050 bsc j 0.009 0.012 k 0.125 0.140 l 0.063 0.070 m 0.015 0.025 n 0.036 0.044 p 0.095 0.110 notes: 1. dimensions are in inches. 2. interpret dimensions and tolerances per asme y14.5m1994. 3. plane x and plane y should be aligned within 0.0015o. m a m 0.005 b m t 12 16 7 g h d 6x c j n m s s 0.025 0.035 u u p u 0.088 0.108 l 8x k 8x a a y t b b y case 648c04 issue d dip package dim min max min max millimeters inches a 0.744 0.783 18.90 19.90 b 0.240 0.260 6.10 6.60 c 0.145 0.185 3.69 4.69 d 0.015 0.021 0.38 0.53 e 0.050 bsc 1.27 bsc f 0.040 0.70 1.02 1.78 g 0.100 bsc 2.54 bsc j 0.008 0.015 0.20 0.38 k 0.115 0.135 2.92 3.43 l 0.300 bsc 7.62 bsc m 0 10 0 10 n 0.015 0.040 0.39 1.01 notes: 1. dimensioning and tolerancing per asme y14.5m, 1994. 2. controlling dimension: inch. 3. dimension l to center of leads when formed parallel. 4. dimension b does not include mold flash. 16 9 18 d g e n k c 16x a m 0.005 (0.13) t seating plane b m 0.005 (0.13) t j 16x m l a a b f t b f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
2109 motorola sensor device data www.motorola.com/semiconductors accelerometer glossary of terms acceleration change in velocity per unit time. acceleration vector vector describing the net acceleration acting upon the device. frequency bandwidth the accelerometer output frequency range. g a unit of acceleration equal to the average force of gravity occurring at the earth's surface. a g is approximately equal to 32.17 ft/s 2 or 9.807 m/s 2 . nonlinearity the maximum deviation of the accelerometer output from a pointtopoint straight line fitted to a plot of acceleration vs. output voltage. this is determined as the percentage of the fullscale output (fso) voltage at fullscale acceleration (40g). ratiometric the variation of the accelerometer's output offset and sensitivity linearly proportional to the variation of the power supply voltage. sensitivity the change in output voltage per unit g of acceleration applied. this is specified in mv/g. sensitive axis the most sensitive axis of the accelerometer. on the dip package, acceleration is in the direction perpendicular to the top of the package (positive acceleration going into the device). on the sip package, acceleration is in the direction perpendicular to the pins. transverse acceleration any acceleration applied 90 to the axis of sensitivity. transverse sensitivity error the percentage of a transverse acceleration that appears at the output. for example, if the transverse sensitivity is 1%, then a +40 g transverse acceleration will cause a 0.4 g signal to appear on the output. transverse sensitivity can result from sensitivity of the gcell to transverse forces. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
2110 motorola sensor device data www.motorola.com/semiconductors f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
31 motorola sensor device data www.motorola.com/semiconductors

section three general information: pressure sensor overview motorola's pressure sensors are silicon micromachined, elec- tromechanical devices featuring device uniformity and con- sistency, high reliability, accuracy and repeatability at competitively low costs. with more than 20 years in pressure sensor engineering, technology development and manufac- turing, these pressure sensors have been designed into auto- motive, industrial, healthcare, commercial and consumer products worldwide. pressure sensors operate in pressures up to 150psi (1000 kpa). for maximum versatility, motorola pressure sensors are single silicon, piezoresistive devices with three levels of de- vice sophistication. the basic sensor device provides uncom- pensated sensing, the next level adds device compensation and the third and most value added pressure sensors are the integrated devices. compensated sensors are available in temperature compensated and calibrated configurations; inte- grated devices are available in temperature compensated, calibrated and signal conditioned (or amplified) configura- tions. each sensor family is available in gauge, absolute and differential pressure references in a variety of packaging and porting options. mini selector guide 32 . . . . . . . . . . . . . . . . . . . . . . . . . device numbering system 34 . . . . . . . . . . . . . . . . . . package offerings 35 . . . . . . . . . . . . . . . . . . . . . . . . . . . orderable part numbers 36 . . . . . . . . . . . . . . . . . . . . . pressure sensor overview general information 37 . . . . . . . . . . . . . . . . . . . . . . . . . . . motorola pressure sensors 38 . . . . . . . . . . . . . . . . . . . . integration 312 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . sensor applications 313 . . . . . . . . . . . . . . . . . . . . . . . . . pressure sensor faq's 314 . . . . . . . . . . . . . . . . . . . . . . data sheets 315 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . application notes 3188 . . . . . . . . . . . . . . . . . . . . . . . . . case outlines 3423 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . reference information reference tables 3439 . . . . . . . . . . . . . . . . . . . . . . . . . . . mounting and handling suggestions 3441 . . . . . . . . . . standard warranty clause 3442 . . . . . . . . . . . . . . . . . . . glossary of terms 3443 . . . . . . . . . . . . . . . . . . . . . . . . . symbols, terms and definitions 3446 . . . . . . . . . . . f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
32 motorola sensor device data www.motorola.com/semiconductors mini selector guide pressure sensors uncompensated pressure sensors product family pressure rating maximum pressure rating maximum pressure rating maximum pressure rating maximum pressure rating maximum offset (typ) (mv) full scale span (typ) sensitivity (mv/kpa) pressure type note maxim u m (psi) maxim u m (kpa) maxim u m (in h2o) maxim u m (cm h20) maxim u m (mm hg) (mv) (typ) (mv) a d g mpx10 1.45 10 40 102 75 20 35 3.5 mpx12 1.45 10 40 102 75 20 55 3.5 mpx53 7 50 200 510 375 20 60 1.2 note: a = absolute, d = differential, g = gauge, v = vacuum compensated pressure sensors product family pressure rating maximum pressure rating maximum pressure rating maximum pressure rating maximum pressure rating maximum offset (mv) full scale span (typ) sensitivity (mv/kpa) pressure type note maxim u m (psi) maxim u m (kpa) maxim u m (in h2o) maxim u m (cm h20) maxim u m (mm hg) (typ) (mv) a d g mpx2010 1.45 10 40 102 75 1.0 25 2.5 mpx2053 7 50 201 510 375 1.0 40 0.8 v mpx2102 14.5 100 400 1020 750 2.0 40 0.4 14.5 100 400 750 1.0 40 0.4 v mpx2202 29 200 800 2040 1500 1.0 40 0.2 29 200 800 1500 1.0 40 0.2 v mpx2050 7 50 201 510 375 1.0 40 0.8 mpx2100 14.5 100 400 1020 750 2.0 40 0.4 14.5 100 400 750 1.0 40 0.4 v mpx2200 29 200 800 2040 1500 1.0 40 0.2 29 200 800 1500 1.0 40 0.2 v note: a = absolute, d = differential, g = gauge, v = vacuum compensated medical grade pressure sensors product family pressure rating maximum pressure rating maximum pressure rating maximum pressure rating maximum pressure rating maximum supply voltage (typ) offset maximum (mv) sensitivity (mv/kpa) pressure type note maxim u m (psi) maxim u m (kpa) maxim u m (in h2o) maxim u m (cm h20) maxim u m (mm hg) (typ) (vdc) (mv) a d g mpxc2011 1.45 10 40 102 75 10.0 1.0 n/a mpx2300 5.8 40 161 408 300 6.0 0.75 5.0 note: a = absolute, d = differential, g = gauge, v = vacuum f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
33 motorola sensor device data www.motorola.com/semiconductors pressure sensors (continued) integrated pressure sensors product family pressure rating maximum pressure rating maximum pressure rating maximum pressure rating maximum pressure rating maximum full scale span sensitivity (mv/kpa) accuracy 0 c85 c (% of pressure type note (psi) (kpa) (in h2o) (cm h2o) (mm hg) (typ) (vdc) vfss) a d g mpx4080 11.6 80 321 815 600 4.3 54 3.0 mpx4100 15.2 105 422 1070 788 4.6 54 1.8 mpx4101 14.8 102 410 1040 765 4.6 54 1.8 mpxh6101 14.8 102 410 1040 765 4.6 54 1.8 mpx4105 15.2 105 422 1070 788 4.6 51 1.8 mpx4115 16.7 115 462 1174 863 4.6 46 1.5 16.7 115 462 1174 863 4 38 1.5 v mpx6115 16.7 115 462 1174 863 4.6 46 1.5 mpx4200 29 200 803 2040 1500 4.6 26 1.5 mpx4250 36 250 1000 2550 1880 4.7 20 1.5 36 250 1000 2550 1880 4.7 19 1.4 mpxv4006 0.87 6 24 61 45 4.6 766 5.0 v mpxv5004 0.57 4 16 40 29 3.9 1000 2.5 v mpx5010 1.45 10 40 102 75 4.5 450 5.0 v mpx5050 7.25 50 201 510 375 4.5 90 2.5 mpx5100 14.5 100 401 1020 750 4.5 45 2.5 16.7 115 462 1174 863 4.5 45 2.5 mpx5500 72.5 500 2000 5100 3750 4.5 9 2.5 mpx5700 102 700 2810 7140 5250 4.5 6 2.5 mpx5999 150 1000 4150 10546 7757 4.5 5 2.5 mpxh6300 44 300 1200 3060 2250 4.7 16 1.8 note: a = absolute, d = differential, g = gauge, v = vacuum f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
34 motorola sensor device data www.motorola.com/semiconductors device numbering system for pressure sensors m px a 2 xxx a p x t1 category qualified standard custom device prototype device m s p, x pressure sensors package type unibody small outline package (sop) small outline media resistant package chip pak super small outline package (ssop) mpak super small outline package (tpmp) none a/v az c h m y features* uncompensated temperature compensated/ calibrated open temperature compensated/ calibrated/signal conditioned automotive accuracy temperature compensated/ calibrated/signal conditioned high temperature open cmos none 2 3 4 5 6 7 8 shipping method trays tape and reel 1 indicates part orientation in tape rail none t1 u no leadform open (consult factory) open sop only none 0 1 thru 2 3 thru 5 6 thru 7 leadform options type of device absolute gauge differential vacuum/gauge a g d v porting style axial port (small outline package) ported single port (ap, gp, gvp) dual port (dp) stovepipe port (unibody) axial port (unibody) c p s sx rated pressure in kpa, except for mpx2300, expressed in mmhg. (6 = gull wing/surface mount) (7 = 87 degrees/dip) note: actual product marking may be abbreviated due to space constraints but packaging label will reflect full part number. *only applies to qualified and prototype devices. this does not apply to custom devices. examples: mpx10dp 10 kpa uncompensated, differential device in minibody package, ported, no leadform, shipped in trays. mpxa4115a6t1 115 kpa automotive temperature compensated and calibrated device with signal conditioning, sop surface mount with gull wing leadform, shipped in tape and reel. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
35 motorola sensor device data www.motorola.com/semiconductors what are the pressure packaging options? (sizes not to scale) unibody basic element case 344 suffix a / d unibody single port case 344b suffix ap / gp unibody dual port case 344c suffix dp unibody basic element case 867 suffix a / d unibody single port case 867b suffix ap / gp unibody dual port case 867c suffix dp unibody axial port case 867f suffix asx / gsx unibody stovepipe port case 867e suffix as / gs preferred pressure sensor packaging options pressure sensor packaging sop case 482 suffix ag / g6 sop case 482b suffix g7u sop axial port case 482a suffix ac6 / gc6 sop axial port case 482c suffix gc7u medical chip pak case 423a suffix dt1 unibody stovepipe port case 344e suffix as / gs j mpak case 1320 suffix a / d mpak axial port case 1320a suffix as / gs sop side port case 1369 suffix ap / gp sop dual port case 1351 suffix dp sop vacuum port case 1368 suffix gvp ssop case 1317 suffix a6 ssop axial port case 1317a suffix ac6 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
36 motorola sensor device data www.motorola.com/semiconductors orderable part numbers pressure sensor orderable part numbers uncompensated mpx2102d integrated mpx4100a mpx4250a mpx10d mpx2102gp mpxv5004gc6t1 mpx4100ap mpx4250ap mpx10dp mpx2102dp mpxv5004gc6u mpx4100as mpxa4250ac6t1 mpx10gp mpx2102gsx mpxv5004gc7u mpxa4100ac6u mpxa4250ac6u mpx10gs mpx2102gvp mpxv5004g6t1 mpxa4100a6t1 mpxa4250a6t1 MPXV10GC6T1 mpxm2102d mpxv5004g6u mpxa4100a6u mpxa4250a6u mpxv10gc6u mpxm2102dt1 mpxv5004g7u mpxaz4100ac6t1 mpxh6300acgu mpxv10gc7u mpxm2102gs mpxv5004gp mpxaz4100ac6u mpxh6300ac6t1 mpx12d mpxm2102gst1 mpxv5004dp mpxaz4100a6t1 mpxh6300a6u mpx12dp mpxv2102gp mpxv5004gvp mpxaz4100a6u mpxh6300a6t1 mpx12gp mpxv2102dp mpxv4006gc6t1 mpx4101a mpx5700d mpx53d mpx2102a mpxv4006gc6u mpxa4101ac6u mpx5700dp mpx53dp mpx2102ap mpxv4006gc7u mpxh6101a6t1 mpx5700gp mpx53gp mpx2102asx mpxv4006g6t1 mpxh6101a6u mpx5700gs mpxv53gc6t1 mpxm2102a mpxv4006g6u mpx4105a mpxv6115vc6u mpxv53gc6u mpxm2102at1 mpxv4006g7u mpxv4115vc6u mpxaz6115a6u mpxv53gc7u mpxm2102as mpxv4006gp mpxv4115v6t1 mpxaz6115a6t1 compensated mpxm2102ast1 mpxv4006dp mpxv4115v6u mpxaz6115ac6u mpx2300dt1 mpx2100d mpx5010d mpx5700a mpxaz6115ac6t1 mpx2301dt1 mpx2100gp mpx5010dp mpx5700ap mpx2010d mpx2100dp mpx5010dp1 mpx5700as mpx2010gp mpx2100gsx mpx5010gp mpx5999d mpx2010dp mpx2100gvp mpx5010gs mpx4115a mpx2010gs mpx2100a mpx5010gsx mpx4115ap mpx2010gsx mpx2100ap mpxv5010gc6t1 mpx4115as mpxm2010d mpx2100asx mpxv5010gc6u mpxa4115ac6t1 mpxm2010dt1 mpx2202d mpxv5010gc7u mpxa4115ac6u mpxm2010gs mpx2202gp mpxv5010g6u mpxa4115a6t1 mpxm2010gst1 mpx2202dp mpxv5010g7u mpxa4115a6u mpxc2011dt1 mpx2202gsx mpxv5010gp mpxa4115ap mpxc2012dt1 mpx2202gvp mpxv5010dp mpxaz4115ac6t1 mpxv2010gp mpxm2202d mpx5500d mpxaz4115ac6u mpxv2010dp mpxm2202dt1 mpx5500dp mpxaz4115a6t1 mpx2053d mpxm2202gs mpx5050d mpxaz4115a6u mpx2053gp mpxm2202gst1 mpx5050dp mpxa6115ac6t1 mpx2053dp mpxv2202gp mpx5050gp1 mpxa6115ac6u mpx2053gsx mpxv2202dp mpx5050gp mpxa6115a6t1 mpx2053gvp mpx2202a mpxv5050gp mpxa6115a6u mpxm2053d mpx2202ap mpxv5050dp mpxh6115a6t1 mpxm2053dt1 mpx2202asx mpx5100d mpxh6115a6u mpxm2053gs mpxm2202a mpx5100dp mpxh6115ac6t1 mpxm2053gst1 mpxm2202at1 mpx5100gp mpxh6115ac6u mpxv2053gp mpxm2202as mpx5100gsx mpx4200a mpxv2053dp mpxm2202ast1 mpx5100a mpx4250d mpx2050d mpx2200d mpx5100ap mpx4250dp mpx2050gp mpx2200gp mpx4080d mpx4250gp mpx2050dp mpx2200dp mpx2050gsx mpx2200gsx mpx2200gvp mpx2200a mpx2200ap f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
37 motorola sensor device data www.motorola.com/semiconductors general product information performance, competitive price and application versatility are just a few of the motorola pressure sensor advantages. pressure sensor applications versatility for motorola's pressure sensors, new applications emerge every day as engineers and designers realize that they can convert their expensive mechanical pressure sensors to motorola's lowercost, semiconductorbased devices. applications include automotive and aviation, industrial, healthcare and medical products and systems. performance the performance of motorola pressure sensors is based on its patented strain gauge design. unlike the more conventional pressure sensors which utilize four closely matched resistors in a distributed wheatstone bridge config- uration, the device uses only a single piezoresistive element ion implanted on an etched silicon diaphragm to sense the stress induced on the diaphragm by an external pressure. the extremely linear output is an analog voltage that is proportional to pressure input and ratiometric with supply voltage. high sensitivity and excellent long-term repeatability make these sensors suitable for the most demanding applications. accuracy computer controlled laser trimming of on-chip calibration and compensation resistors provide the most accurate pressure measurement over a wide temperature range. temperature effect on span is typically 0.5% of full scale over a temperature range from 0 to 85 c, while the effect on offset voltage over a similar temperature range is a maximum of only 1 mv. unlimited versatility choice of specifications: motorola's pressure sensors are available in pressure ranges to fit a wide variety of automotive, healthcare, consumer and industrial applications. choice of measurement: devices are available for differential, absolute, or gauge pressure measurements. choice of chip complexity: motorola's pressure sensors are available as the basic sensing element, with temperature compensation and cali- bration, or with full signal conditioning circuitry included on the chip. uncompensated devices permit external compen- sation to any degree desired. choice of packaging: available as a basic element for custom mounting, or in conjunction with motorola's designed ports, printed circuit board mounting is easy. our small outline and super small outline packaging options provide surface mount, low profile, and top piston fit package selections. alternate packaging material, which has been designed to meet biocompatibility requirements, is also available. curves of span and offset errors indicate the accuracy resulting from on-chip compensation and laser trimming. 2 1.5 1 0.5 0 0.5 1 1.5 2 50 span error (% full scale) offset error (mv) temperature ( c) 25 0 25 50 75 100 125 150 error band limit span error offset error error band limit figure 1. typical output versus pressure differential pressure differential 70 60 40 50 30 output (mvdc) 20 10 0 0 10 20 30 40 50 60 70 80 90 100 2.0 4.0 6.0 8.0 10 12 14 16 40 c +25 c +125 c v s = 3.0 vdc p1 > p2 psi kpa span range (typ) offset (typ) figure 2. temperature error band limit and typical span and offset errors f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
38 motorola sensor device data www.motorola.com/semiconductors motorola pressure sensors introduction motorola pressure sensors combine advanced piezoresistive sensor architecture with integrated circuit technology to offer a wide range of pressure sensing devices for automotive, medical, consumer and industrial applications. selection versatility includes choice of: pressure ranges in psi application measurements 0 to 1.45, 0 to 6, 0 to 7.3, 0 to 14.5, 0 to 29, 0 to 75, 0 to 100, absolute, differential, gauge 0 to 150 psi. sensing options package options uncompensated, temperature compensated/calibrated, ? basic element, ported elements for specific measurements and signal conditioned (with onchip amplifiers) ? surface mount and through hole, low profile packages the basic structure the motorola pressure sensor is designed utilizing a monolithic silicon piezoresistor, which generates a changing output voltage with variations in applied pressure. the resistive element, which constitutes a strain gauge, is ion implanted on a thin silicon diaphragm. applying pressure to the diaphragm results in a resistance change in the strain gauge, which in turn causes a change in the output voltage in direct proportion to the applied pressure. the strain gauge is an integral part of the silicon diaphragm, hence there are no temperature effects due to differences in thermal expansion of the strain gauge and the diaphragm. the output parameters of the strain gauge itself are temperature dependent, however, requiring that the device be compensated if used over an extensive tempera- ture range. simple resistor networks can be used for narrow temperature ranges, i.e., 0 c to 85 c. for temperature ranges from 40 c to +125 c, more extensive compensa- tion networks are necessary. motorola's localized sensing elements excitation current is passed longitudinally through the resistor (taps 1 and 3), and the pressure that stresses the diaphragm is applied at a right angle to the current flow. the stress establishes a transverse electric field in the resistor that is sensed as voltage at taps 2 and 4, which are located at the midpoint of the resistor (figure 3a). the transducer (figure 3) uses a single element eliminat- ing the need to closely match the four stress and t empera- ture sensitive resistors that form a distributed wheatstone bridge design. at the same time, it greatly simplifies the additional circuitry necessary to accomplish calibration and temperature compensation. the offset does not depend on matched resistors but instead on how well the transverse voltage taps are aligned. this alignment is accomplished in a single photolithographic step, making it easy to control, and is only a positive voltage, simplifying schemes to zero the offset. figure 3. xducer ? sensor element e top view pin # 1. ground 2. +v out 3. v s 4. v out ???? ???? ???? ???? ??? ??? ??? etched diaphragm boundary transverse voltage strain gauge resistor active element s+ s voltage taps 3 2 14 etched diaphragm boundary transverse voltage strain gauge resistor active element has four p resistors s+ s 3 2 1 4 pin # 1. ground 2. +v out 3. v s 4. v out ?? ?? ? figure 3a. localized sensing element f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
figure 4. linearity specification comparison relative voltage output least square deviation 0 50 100 pressure (% fullscale) straight line deviation least squares fit exaggerated performance curve offset end point straight line fit 39 motorola sensor device data www.motorola.com/semiconductors linearity linearity refers to how well a transducer's output follows the equation: v out = v off + sensitivity x p over the operating pressure range. there are two basic methods for calculating nonlinearity: (1) end point straight line fit (see figure 4) or (2) a least squares best line fit. while a least squares fit gives the abest caseo linearity error (lower numerical value), the calculations required are burdensome. conversely, an end point fit will give the aworst caseo error (often more desirable in error budget calculations) and the calculations are more straightforward for the user. motorola's specified pressure sensor linearities are based on the end point straight line method measured at the midrange pressure. operation motorola pressure sensors provide three types of pressure measurement: absolute pressure, differential pressure and gauge pressure. absolute pressure sensors measure an external pressure relative to a zeropressure reference (vacuum) sealed inside the reference chamber of the die during manufacture. this corresponds to a deflection of the diaphragm equal to approximately 14.5 psi (one atmo- sphere), generating a quiescent fullscale output for the mpxh6101a6t1 (14.5 psi) sensor, and a halfscale output for the mpx4200a (29 psi) device. measurement of external pressure is accomplished by applying a relative negative pressure to the apressureo side of the sensor. differential pressure sensors measure the difference between pressures applied simulta- neously to opposite sides of the diaphragm. a positive pressure applied to the apressureo side generates the same (positive) output as an equal negative pressure applied to the avacuumo side. figure 5. pressure measurements gauge pressure readings are a special case of differential measure- ments in which the pressure applied to the apressureo side is measured against the ambient atmospheric pressure applied to the avacuumo side through the vent hole in the chip of the differential pressure sensor elements. negative pressure v off 1 atm p max increasing vacuum increasing pressure positive pressure negative pressure v off differential pressure increasing p max absolute sensor differential sensor vacuum motorola sensing elements can withstand pressure inputs as high as four times their rated capacity, although accuracy at pressures exceeding the rated pressure will be reduced. when excessive pressure is reduced, the previous linearity is immediately restored. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
310 motorola sensor device data www.motorola.com/semiconductors output (mvdc) kpa psi 40 35 30 25 15 10 5 0 5 025 3.62 50 7.25 75 10.87 100 14.5 span range (typ) offset (typ) typ 20 pressure differential output (mvdc) 100 90 80 70 60 50 40 30 20 10 0 psi kpa 01 234 5 6 7 8 01020 304050 40 c typical electrical characteristic curves v s = 10 vdc t a = 25 c mpx2100 p1 > p2 max min + 125 c t a = 40 to + 125 c compensated compensated v s = 10 vdc uncompensated v s = 3 vdc p1 > p2 uncompensated figure 6. output versus pressure differential figure 7. typicaloutput voltage versus pressure and temperature for compensated and uncompensated devices figure 8. signal conditioned mpx5100 +25 c 0.5 0 1.0 typ min 4.5 5.0 4.0 3.5 3.0 2.5 2.0 1.5 010 50 70 110 20 30 40 60 80 90 100 max output (volts) differential pressure (in kpa) transfer function: vout = vs* (0.009*p 0.04) error vs = 5.0 vdc temp = 0 to 85 c mpx5100d p1 > p2 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
311 motorola sensor device data www.motorola.com/semiconductors unibody crosssectional drawings figure 9. crosssectional diagrams (not to scale) s i l i cone gel die coat wire bond lead frame di fferent i al / gauge die stainless steel metal cover epoxy case differential/gauge element die bond s i l i cone gel die coat wire bond lead frame absolute die stainless steel metal cover epoxy case die bond absolute element p1 p2 p1 figure 9 illustrates the absolute sensing configuration (right) and the differential or gauge configuration in the basic chip carrier (case 344). a silicone gel isolates the die surface and wire bonds from harsh environments, while allowing the pressure signal to be transmitted to the silicon diaphragm. the mpx series pressure sensor operating characteristics and internal reliability and qualification tests are based on use of dry air as the pressure media. media other than dry air may have adverse effects on sensor performance and long term stability. contact the factory for information regarding media compatibility in your application. figure 10. crosssectional diagram (not to scale) fluoro silicone die coat wire bonds lead frame die stainless steel metal cover epoxy case p1 figure 10 illustrates the differential/gauge die in the basic chip carrier (case 473). a silicone gel isolates the die surface and wirebonds from the environment, while allowing the pressure signal to be transmitted to the silicon diaphragm. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
312 motorola sensor device data www.motorola.com/semiconductors integration on-chip signal conditioning to make the designer's job even easier, motorola's integrated devices carry sensor technology one step further. in addition to the on-chip temperature compensation and calibration offered currently on the 2000 series, amplifier signal conditioning has been integrated on-chip in the 4000, 5000 and 6000 series to allow interface directly to any microcomputer with an on-board a/d converter. the signal conditioning is accomplished by means of a four-stage amplification network, incorporating linear bipolar processing, thin-film metallization techniques, and interac- tive laser trimming to provide the state-of-the-art in sensor technology. 1.0 f ips output 3 5 v 0.01 f 2 1 recommended power supply decoupling. for output filtering recommendations, please refer to application note an1646. 470 pf design considerations for different levels of sensor integration design advantages design considerations uncompensated sensors high sensitivity devicetodevice variation in offset and span lowest device cost temperature compensation circuitry required lowlevel output allows flexibility of signal conditioning requires signal conditioning/ amplification of output signal relatively low input impedance (400 w typical) temperature compensated & calibrated (2000 series) reduced devicetodevice variations in offset and span lower sensitivity due to span compensation (compared to uncompensated) reduced temperature drift in offset and span priced higher than uncompensated device reasonable input impedance (2k w typical) requires signal conditioning/ amplification of output signal low level output allows flexibility in signal conditioning integrated pressure sensors (4000, 5000 and 6000 series) no amplification needed direct interface to mpu priced higher than compensated/ uncompensated device signal conditioning, calibration of span and offset, temperature compensation included onchip f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
313 motorola sensor device data www.motorola.com/semiconductors sensor applications automotive/aviation applications ? fuel level indicator ? altimeters ? air speed indicator ? ejection seat control ? turbo boost control ? manifold vacuum control ? fuel flow metering ? oil filter flow indicator ? oil pressure sensor ? air flow measurement ? antistart ? breathalizer systems ? smart suspension systems ? variometerhang glider & sailplanes ? automotive speed control healthcare applications ? blood pressure ? esophagus pressure ? heart monitor ? interoccular pressure ? saline pumps ? kidney dialysis ? blood gas analysis ? blood serum analysis ? seating pressure (paraplegic) ? respiratory control ? intravenous infusion pump control ? hospital beds ? drug delivery ? iupc ? patient monitors industrial/commercial applications ? electronic fire fighting control ? flow control ? barometer ? hvac systems ? tire pressure monitoring ? water filtered systems (flow rate indicator) ? air filtered systems (flow rate indicator) ? tactile sensing for robotic systems ? boiler pressure indicators ? end of tape readers ? disc drive control/protection systems ? ocean wave measurement ? diving regulators ? oil well logging ? building automation (balancing, load control, windows) ? fluid dispensers ? explosion sensing e shock wave monitors ? load cells ? autoclave release control ? soil compaction monitor e construction ? water depth finders (industrial, sport fishing/diving) ? pneumatic controls e robotics ? pinch roller pressure e paper feed ? blower failure safety switch e computer ? vacuum cleaner control ? electronic drum ? pressure controls systems e building, domes ? engine dynamometer ? water level monitoring ? altimeters motorola has tested media tolerant sensor devices in selected solutions or environments and test results are based on particula r conditions and procedures selected by motorola. customers are advised that the results may vary for actual services conditions. customers are cautioned that they are responsible to determine the media compatibility of sensor devices in their applications and the foreseeable use and m isuses of their applications. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
314 motorola sensor device data www.motorola.com/semiconductors pressure sensor faq's we have discovered that many of our customers have similar questions about certain aspects of our pressure sensor technology and operation. here are the most frequently asked questions and answers that have been explained in relatively nontechnical terms. q. how do i calculate total pressure error for my applications? a. you can calculate total error in two fashions, worst case error and most probable error. worst case error is taking all the individual errors and adding them up, while most probable error sums the squares of the individual errors and then take the square root of the total. in summary, error (worst case) = e1 + e2 + e3 + ... + en, while error (most probable) = sqrt[(e1)2 + (e2)2 + (e3)2 + ... (en)2]; please note that not all errors may apply in your individual application. q. what is the media tolerance of our pressure sen- sors? a. most motorola pressure sensors are specifically de- signed for dry air applications. however, motorola now offers an mpxaz series specifically designed for im- proved media resistance. this series incorporates a durable barrier that allows the sensor to operate reliably in high humidity conditions as well as environments containing common automotive media. note: applica- tions exposing the sensor to media other than what has been specified could potentially limit the lifetime of the sensor. please consult the motorola factory for more information regarding media compatibility in your specific application. q. can i pull a vacuum on p1? a. motorola pressure sensors are designed to measure pressure in one direction and are not bidirectional. it is possible to measure either a positive pressure or a negative pressure, but not both. for example, the sensor can be designed to accept a opositiveo pressure on the p1 port, providing that p1 is greater or equal to p2 while staying with in the sensors specified pressure range. or, the sensor can measure onegativeo pressure (a vacu- um)by applying the pressure to the p2 port, again while p1 is greater or equal to p2 and staying within the sensors specified range. our pressure sensors are based on a silicon diaphragm and can not tolerate a pressure that alternates from positive to negative without resulting damage. the devices are rated for over pressure and burst but should not be intentionally designed to operate in a bidirection- al manner. if you need to measure both a positive and negative pressure within the same system, we suggest designing with two separate sensors, one for each pressure type. or, a mechanical pressure transducer should be utilized. q. what will happen if i run the pressure sensor beyond the rated operating pressure? a. for bare elements (uncompensated and compensated series devices), when you take the sensor higher than the rated pressure, the part will still provide an output increasing linearly with pressure. when you go below the minimum rated pressure, the output of the sensor will eventually go negative. motorola, however, does not guarantee electrical specifications beyond the rated operating pressure range specified in the data sheet of each device. the integrated series devices will not function at all beyond the rated pressure of the part. these series of parts will saturate at near 4.8 v and 0.2 v and thus no further change in output will occur. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
315 motorola sensor device data www.motorola.com/semiconductors ! the mpx10 and mpxv10gc series devices are silicon piezoresistive pressure sensors providing a very accurate and linear voltage output e directly proportional to the applied pressure. these standard, low cost, uncompensated sensors permit manufacturers to design and add their own external temperature compensation and signal conditioning networks. compensation techniques are simplified because of the predictability of motorola's single element strain gauge design. figure 1 shows a schematic of the internal circuitry on the standalone pressure sensor chip. features ? low cost ? patented silicon shear stress strain gauge design ? ratiometric to supply voltage ? easy to use chip carrier package options ? differential and gauge options ? durable epoxy unibody element or thermoplastic (pps) surface mount package application examples ? air movement control ? environmental control systems ? level indicators ? leak detection ? medical instrumentation ? industrial controls ? pneumatic control systems ? robotics figure 1. uncompensated pressure sensor schematic 3 sensing element 2 4 + v out v out + v s 1 gnd voltage output versus applied differential pressure the output voltage of the differential or gauge sensor increases with increasing pressure applied to the pressure side (p1) relative to the vacuum side (p2). similarly, output voltage increases as increasing vacuum is applied to the vacuum side (p2) relative to the pressure side (p1).
semiconductor technical data

0 to 10 kpa (0 1.45 psi) 35 mv full scale span (typical) note: pin 1 is noted by the notch in the lead. pin number mpx10d case 344 mpx10dp case 344c 1 2 gnd +v out 3 4 v s v out unibody package small outline package mpxv10gc6u case 482a mpxv10gc7u case 482c pin number 1 2 3 gnd +v out vs 5 6 7 n/c n/c n/c 4v out 8 n/c note: pin 1 is noted by the notch in the lead. rev 10 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

316 motorola sensor device data www.motorola.com/semiconductors maximum ratings (note) rating symbol value unit maximum pressure (p1 > p2) p max 75 kpa burst pressure (p1 > p2) p burst 100 kpa storage temperature t stg 40 to +125 c operating temperature t a 40 to +125 c note: exposure beyond the specified limits may cause permanent damage or degradation to the device. operating characteristics (v s = 3.0 vdc, t a = 25 c unless otherwise noted, p1 > p2) characteristic symbol min typ max unit differential pressure range (1) p op 0 e 10 kpa supply voltage (2) v s e 3.0 6.0 vdc supply current i o e 6.0 e madc full scale span (3) v fss 20 35 50 mv offset (4) v off 0 20 35 mv sensitivity d v/ d p e 3.5 e mv/kpa linearity (5) e 1.0 e 1.0 %v fss pressure hysteresis (5) (0 to 10 kpa) e e 0.1 e %v fss temperature hysteresis (5) ( 40 c to +125 c) e e 0.5 e %v fss temperature coefficient of full scale span (5) tcv fss 0.22 e 0.16 %v fss / c temperature coefficient of offset (5) tcv off e 15 e m v/ c temperature coefficient of resistance (5) tcr 0.28 e 0.34 %z in / c input impedance z in 400 e 550 w output impedance z out 750 e 1250 w response time (6) (10% to 90%) t r e 1.0 e ms warmup time (7) e e 20 e ms offset stability (8) e e 0.5 e %v fss notes: 1. 1.0 kpa (kilopascal) equals 0.145 psi. 2. device is ratiometric within this specified excitation range. operating the device above the specified excitation range may induce additional error due to device selfheating. 3. full scale span (v fss ) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 4. offset (v off ) is defined as the output voltage at the minimum rated pressure. 5. accuracy (error budget) consists of the following: ? linearity: output deviation from a straight line relationship with pressure, using end point method, over the specified pressure range. ? temperature hysteresis: output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. ? pressure hysteresis: output deviation at any pressure within the specified range, when this pressure is cycled to and from the minimum or maximum rated pressure, at 25 c. ? tcspan: output deviation at full rated pressure over the temperature range of 0 to 85 c, relative to 25 c. ? tcoffset: output deviation with minimum rated pressure applied, over the temperature range of 0 to 85 c, relative to 25 c. ? tcr: z in deviation with minimum rated pressure applied, over the temperature range of 40 c to +125 c, relative to 25 c. 6. response time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when s ubjected to a specified step change in pressure. 7. warmup time is defined as the time required for the product to meet the specified output voltage after the pressure has been stabilized. 8. offset stability is the product's output deviation when subjected to 1000 hours of pulsed pressure, temperature cycling with bias test. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

317 motorola sensor device data www.motorola.com/semiconductors temperature compensation figure 2 shows the typical output characteristics of the mpx10 and mpxv10gc series over temperature. because this strain gauge is an integral part of the silicon diaphragm, there are no temperature effects due to differ- ences in the thermal expansion of the strain gauge and the diaphragm, as are often encountered in bonded strain gauge pressure sensors. however, the properties of the strain gauge itself are temperature dependent, requiring that the device be temperature compensated if it is to be used over an extensive temperature range. temperature compensation and offset calibration can be achieved rather simply with additional resistive components, or by designing your system using the mpx2010d series sensor. several approaches to external temperature compensa- tion over both 40 to +125 c and 0 to + 80 c ranges are presented in motorola applications note an840. linearity linearity refers to how well a transducer's output follows the equation: v out = v off + sensitivity x p over the operating pressure range (figure 3). there are two basic methods for calculating nonlinearity: (1) end point straight line fit or (2) a least squares best line fit. while a least squares fit gives the abest caseo linearity error (lower numerical value), the cal- culations required are burdensome. conversely, an end point fit will give the aworst caseo error (often more desirable in error budget calculations) and the calculations are more straightforward for the user. motorola's specified pressure sensor linearities are based on the end point straight line method measured at the midrange pressure. figure 2. output versus pressure differential figure 3. linearity specification comparison figure 4. unibody package e crosssectional diagram (not to scale) silicone die coat wire bond lead frame die stainless steel metal cover epoxy case rtv die bond p1 p2 offset (v off ) 70 output (mvdc) 60 50 40 30 20 10 0 0 max p op span (v fss ) pressure (kpa) actual theoretical linearity pressure differential out p ut ( mv dc) 80 70 60 50 40 30 20 10 0 0 0.3 2.0 0.6 4.0 0.9 6.0 1.2 8.0 10 1.5 psi kpa span range (typ) offset (typ) v s = 3 vdc p1 > p2 40 c +25 c + 125 c figure 4 illustrates the differential or gauge configuration in the basic chip carrier (case 344). a silicone gel isolates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the silicon diaphragm. the mpx10 and mpxv10gc series pressure sensor oper- ating characteristics and internal reliability and qualification tests are based on use of dry air as the pressure media. me- dia other than dry air may have adverse effects on sensor per- formance and long term reliability. contact the factory for information regarding media compatibility in your application. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

318 motorola sensor device data www.motorola.com/semiconductors pressure (p1)/vacuum (p2) side identification table motorola designates the two sides of the pressure sensor as the pressure (p1) side and the vacuum (p2) side. the pressure (p1) side is the side containing silicone gel which isolates the die from the environment. the motorola pres- sure sensor is designed to operate with positive differential pressure applied, p1 > p2. the pressure (p1) side may be identified by using the table below: part number case type pressure (p1) side identifier mpx10d 344 stainless steel cap mpx10dp 344c side with part marking mpx10gp 344b side with port attached mpx10gs 344e side with port attached mpxv10gc6u 482a side with part marking mpxv10gc7u 482c side with part marking ordering information e unibody package mpx10 series pressure sensors are available in differential and gauge configurations. devices are available in the basic element package or with pressure port fittings which provide printed circuit board mounting ease and barbed hose pressure connections. mpx series device type options case type order number device marking basic element differential case 344 mpx10d mpx10d ported elements differential case 344c mpx10dp mpx10dp gauge case 344b mpx10gp mpx10gp gauge case 344e mpx10gs mpx10d ordering information e small outline package (mpxv10gc series) device type/order no packing options case type device marking device type/order no . packing options case type device marking mpxv10gc6u rails case 482a mpxv10g MPXV10GC6T1 tape and reel case 482a mpxv10g mpxv10gc7u rails case 482c mpxv10g f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
319 motorola sensor device data www.motorola.com/semiconductors the mpx12 series device is a silicon piezoresistive pressure sensor providing a very accurate and linear voltage output e directly proportional to the applied pressure. this standard, low cost, uncompensated sensor permits manufacturers to design and add their own external temperature compensating and signal conditioning networks. compensation techniques are simplified because of the predictability of motorola's single element strain gauge design. features ? low cost ? patented silicon shear stress strain gauge design ? ratiometric to supply voltage ? easy to use chip carrier package options ? differential and gauge options ? durable epoxy package application examples ? air movement control ? environmental control systems ? level indicators ? leak detection ? medical instrumentation ? industrial controls ? pneumatic control systems ? robotics figure 1 shows a schematic of the internal circuitry on the standalone pressure sensor chip. figure 1. uncompensated pressure sensor schematic pin 3 sensing element pin 2 pin 4 + v out v out + v s pin 1 voltage output versus applied differential pressure the output voltage of the differential or gauge sensor increases with increasing pressure applied to the pressure side (p1) relative to the vacuum side (p2). similarly, output voltage increases as increasing vacuum is applied to the vacuum side (p2) relative to the pressure side (p1).

semiconductor technical data 0 to 10 kpa (0 1.45 psi) 55 mv full scale span (typical) pin number mpx12d case 344 mpx12dp case 344c 1 2 gnd +v out 3 4 v s v out note: pin 1 is noted by the notch in the lead. rev 3 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

320 motorola sensor device data www.motorola.com/semiconductors maximum ratings (note) rating symbol value unit maximum pressure (p1 > p2) p max 75 kpa burst pressure (p1 > p2) p burst 100 kpa storage temperature t stg 40 to +125 c operating temperature t a 40 to +125 c note: exposure beyond the specified limits may cause permanent damage or degradation to the device. operating characteristics (v s = 3.0 vdc, t a = 25 c unless otherwise noted, p1 > p2) characteristic symbol min typ max unit differential pressure range (1) p op 0 e 10 kpa supply voltage (2) v s e 3.0 6.0 vdc supply current i o e 6.0 e madc full scale span (3) v fss 45 55 70 mv offset (4) v off 0 20 35 mv sensitivity d v/ d p e 5.5 e mv/kpa linearity (5) e 0.5 e 5.0 %v fss pressure hysteresis (5) (0 to 10 kpa) e e 0.1 e %v fss temperature hysteresis (5) ( 40 c to +125 c) e e 0.5 e %v fss temperature coefficient of full scale span (5) tcv fss 0.22 e 0.16 %v fss / c temperature coefficient of offset (5) tcv off e 15 e m v/ c temperature coefficient of resistance (5) tcr 0.28 e 0.34 %z in / c input impedance z in 400 e 550 w output impedance z out 750 e 1250 w response time (6) (10% to 90%) t r e 1.0 e ms warmup time (7) e e 20 e ms offset stability (8) e e 0.5 e %v fss notes: 1. 1.0 kpa (kilopascal) equals 0.145 psi. 2. device is ratiometric within this specified excitation range. operating the device above the specified excitation range may induce additional error due to device selfheating. 3. full scale span (v fss ) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 4. offset (v off ) is defined as the output voltage at the minimum rated pressure. 5. accuracy (error budget) consists of the following: ? linearity: output deviation from a straight line relationship with pressure, using end point method, over the specified pressure range. ? temperature hysteresis: output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. ? pressure hysteresis: output deviation at any pressure within the specified range, when this pressure is cycled to and from the minimum or maximum rated pressure, at 25 c. ? tcspan: output deviation at full rated pressure over the temperature range of 0 to 85 c, relative to 25 c. ? tcoffset: output deviation with minimum rated pressure applied, over the temperature range of 0 to 85 c, relative to 25 c. ? tcr: z in deviation with minimum rated pressure applied, over the temperature range of 40 c to +125 c, relative to 25 c. 6. response time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when s ubjected to a specified step change in pressure. 7. warmup time is defined as the time required for the product to meet the specified output voltage after the pressure has been stabilized. 8. offset stability is the product's output deviation when subjected to 1000 hours of pulsed pressure, temperature cycling with bias test. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

321 motorola sensor device data www.motorola.com/semiconductors temperature compensation figure 2 shows the typical output characteristics of the mpx12 series over temperature. because this strain gauge is an integral part of the silicon diaphragm, there are no temperature effects due to differ- ences in the thermal expansion of the strain gauge and the diaphragm, as are often encountered in bonded strain gauge pressure sensors. however, the properties of the strain gauge itself are temperature dependent, requiring that the device be temperature compensated if it is to be used over an extensive temperature range. temperature compensation and offset calibration can be achieved rather simply with additional resistive components, or by designing your system using the mpx2010d series sensor. several approaches to external temperature compensa- tion over both 40 to +125 c and 0 to + 80 c ranges are presented in motorola applications note an840. linearity linearity refers to how well a transducer's output follows the equation: v out = v off + sensitivity x p over the operating pressure range (figure 3). there are two basic methods for calculating nonlinearity: (1) end point straight line fit or (2) a least squares best line fit. while a least squares fit gives the abest caseo linearity error (lower numerical value), the cal- culations required are burdensome. conversely, an end point fit will give the aworst caseo error (often more desirable in error budget calculations) and the calculations are more straightforward for the user. motoro- la's specified pressure sensor linearities are based on the end point straight line method measured at the midrange pressure. figure 2. output versus pressure differential figure 3. linearity specification comparison figure 4. crosssectional diagram (not to scale) silicone die coat wire bond lead frame die stainless steel metal cover epoxy case rtv die bond p1 p2 offset (v off ) 70 output (mvdc) 60 50 40 30 20 10 0 0 max p op span (v fss ) pressure (kpa) actual theoretical linearity pressure differential out p ut ( mv dc) 80 70 60 50 40 30 20 10 0 0 0.3 2.0 0.6 4.0 0.9 6.0 1.2 8.0 10 1.5 psi kpa span range (typ) offset (typ) v s = 3 vdc p1 > p2 40 c +25 c + 125 c figure 4 illustrates the differential or gauge configuration in the basic chip carrier (case 344). a silicone gel isolates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the silicon diaphragm. the mpx12 series pressure sensor operating characteris- tics and internal reliability and qualification tests are based on use of dry air as the pressure media. media other than dry air may have adverse effects on sensor performance and long term reliability. contact the factory for information re- garding media compatibility in your application. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

322 motorola sensor device data www.motorola.com/semiconductors pressure (p1)/vacuum (p2) side identification table motorola designates the two sides of the pressure sensor as the pressure (p1) side and the vacuum (p2) side. the pressure (p1) side is the side containing silicone gel which isolates the die from the environment. the motorola mpx pressure sensor is designed to operate with positive differen- tial pressure applied, p1 > p2. the pressure (p1) side may be identified by using the table below: part number case type pressure (p1) side identifier mpx12d 344 stainless steel cap mpx12dp 344c side with part marking mpx12gp 344b side with port attached ordering information mpx12 series pressure sensors are available in differential and gauge configurations. devices are available in the basic element package or with pressure port fittings which provide printed circuit board mounting ease and barbed hose pressure connections. mpx series device type options case type order number device marking basic element differential case 344 mpx12d mpx12d ported elements differential case 344c mpx12dp mpx12dp gauge case 344b mpx12gp mpx12gp f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
323 motorola sensor device data www.motorola.com/semiconductors ! !"$%" !#$ "$ "##%" # "# the mpx2010/mpxv2010g series silicon piezoresistive pressure sensors provide a very accurate and linear voltage output e directly proportional to the applied pressure. these sensors house a single monolithic silicon die with the strain gauge and thinfilm resistor network integrated on each chip. the sensor is laser trimmed for precise span, offset calibration and temperature compensation. features ? temperature compensated over 0 c to + 85 c ? ratiometric to supply voltage ? differential and gauge options application examples ? respiratory diagnostics ? air movement control ? controllers ? pressure switching figure 1 shows a block diagram of the internal circuitry on the standalone pressure sensor chip. figure 1. temperature compensated and calibrated pressure sensor schematic v s 3 sensing element thin film temperature compensation and calibration circuitry 2 4 v out+ v out 1 gnd voltage output versus applied differential pressure the output voltage of the differential or gauge sensor increases with increasing pressure applied to the pressure side (p1) relative to the vacuum side (p2). similarly, output voltage increases as increasing vacu- um is applied to the vacuum side (p2) relative to the pressure side (p1). preferred devices are motorola recommended choices for future use and best overall value. semiconductor technical data small outline package surface mount unibody package mpx2010gp case 344b mpx2010gsx case 344f pin number note: pin 1 is noted by the notch in the lead. 1 2 3 gnd +v out v s 5 6 7 n/c n/c n/c 4v out 8 n/c mpx2010d case 344 mpx2010dp case 344c mpx2010gs case 344e mpxv2010dp case 1351 mpxv2010gp case 1369
compensated pressure sensor 0 to 10 kpa (0 to 1.45 psi) full scale span: 25 mv motorola preferred device pin number 1 2 gnd +v out 3 4 v s v out note: pin 1 is noted by the notch in the lead. rev 9 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

324 motorola sensor device data www.motorola.com/semiconductors maximum ratings (note) rating symbol value unit maximum pressure (p1 > p2) p max 75 kpa storage temperature t stg 40 to +125 c operating temperature t a 40 to +125 c note: exposure beyond the specified limits may cause permanent damage or degradation to the device. operating characteristics (v s = 10 vdc, t a = 25 c unless otherwise noted, p1 > p2) characteristic symbol min typ max unit pressure range (1) p op 0 e 10 kpa supply voltage (2) v s e 10 16 vdc supply current i o e 6.0 e madc full scale span (3) v fss 24 25 26 mv offset (4) v off 1.0 e 1.0 mv sensitivity d v/ d p e 2.5 e mv/kpa linearity (5) e 1.0 e 1.0 %v fss pressure hysteresis (5) (0 to 10 kpa) e e 0.1 e %v fss temperature hysteresis (5) ( 40 c to +125 c) e e 0.5 e %v fss temperature effect on full scale span (5) tcv fss 1.0 e 1.0 %v fss temperature effect on offset (5) tcv off 1.0 e 1.0 mv input impedance z in 1000 e 2550 w output impedance z out 1400 e 3000 w response time (6) (10% to 90%) t r e 1.0 e ms warmup e e 20 e ms offset stability (7) e e 0.5 e %v fss notes: 1. 1.0 kpa (kilopascal) equals 0.145 psi. 2. device is ratiometric within this specified excitation range. operating the device above the specified excitation range may i nduce additional error due to device selfheating. 3. full scale span (v fss ) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 4. offset (v off ) is defined as the output voltage at the minimum rated pressure. 5. accuracy (error budget) consists of the following: ? linearity: output deviation from a straight line relationship with pressure, using end point method, over the specified pressure range. ? temperature hysteresis: output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. ? pressure hysteresis: output deviation at any pressure within the specified range, when this pressure is cycled to and from the minimum or maximum rated pressure, at 25 c. ? tcspan: output deviation at full rated pressure over the temperature range of 0 to 85 c, relative to 25 c. ? tcoffset: output deviation with minimum rated pressure applied, over the temperature range of 0 to 85 c, relative to 25 c. 6. response time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when s ubjected to a specified step change in pressure. 7. offset stability is the product's output deviation when subjected to 1000 hours of pulsed pressure, temperature cycling with bias test. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

325 motorola sensor device data www.motorola.com/semiconductors onchip temperature compensation and calibration figure 2. output versus pressure differential min typ offset (typ) 30 20 15 10 5 output (mvdc) 25 0 5 kpa psi 2.5 0.362 5 0.725 7.5 1.09 10 1.45 a max span range (typ) v s = 10 vdc t a = 25 c p1 > p2 figure 2 shows the output characteristics of the mpx2010/mpxv2010g series at 25 c. the output is direct- ly proportional to the differential pressure and is essentially a straight line. the effects of temperature on full scale span and offset are very small and are shown under operating characteristics. this performance over temperature is achieved by having both the shear stress strain gauge and the thinfilm resistor circuitry on the same silicon diaphragm. each chip is dynam- ically laser trimmed for precise span and offset calibration and temperature compensation. figure 3. unibody package e crosssectional diagram (not to scale) silicone die coat wire bond lead frame die stainless steel metal cover epoxy case rtv die bond p1 p2 figure 3 illustrates the differential/gauge die in the basic chip carrier (case 344). a silicone gel isolates the die surface and wire bonds from the environment, while allowing the pres- sure signal to be transmitted to the silicon diaphragm. the mpx2010/mpxv2010g series pressure sensor oper- ating characteristics and internal reliability and qualification tests are based on use of dry air as the pressure media. me- dia other than dry air may have adverse effects on sensor performance and long term reliability. contact the factory for information regarding media compatibility in your application. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

326 motorola sensor device data www.motorola.com/semiconductors linearity linearity refers to how well a transducer's output follows the equation: v out = v off + sensitivity x p over the operating pressure range. there are two basic methods for calculating nonlinearity: (1) end point straight line fit (see figure 5) or (2) a least squares best line fit. while a least squares fit gives the abest caseo linearity error (lower numerical value), the calculations required are burdensome. conversely, an end point fit will give the aworst caseo error (often more desirable in error budget calculations) and the cal- culations are more straightforward for the user. motorola's specified pressure sensor linearities are based on the end point straight line method measured at the midrange pressure. figure 4. linearity specification comparison least square deviation relat i ve voltage out p ut pressure (% fullscale) 0 50 100 end point straight line fit exaggerated performance curve least squares fit straight line deviation offset pressure (p1) / vacuum (p2) side identification table motorola designates the two sides of the pressure sensor as the pressure (p1) side and the vacuum (p2) side. the pressure (p1) side is the side containing silicone gel which isolates the die from the environment. the motorola mpx pressure sensor is designed to operate with positive differen- tial pressure applied, p1 > p2. the pressure (p1) side may be identified by using the table below: part number case type pressure (p1) side identifier mpx2010d 344 stainless steel cap mpx2010dp 344c side with part marking mpx2010gp 344b side with port attached mpx2010gs 344e side with port attached mpx2010gsx 344f side with port attached mpxv2010gp 1369 side with port attached mpxv2010dp 1351 side with part marking ordering information e unibody package (mpx2010 series) mpx series device type options case type order number device marking basic element differential 344 mpx2010d mpx2010d ported elements differential, dual port 344c mpx2010dp mpx2010dp gauge 344b mpx2010gp mpx2010gp gauge, axial 344e mpx2010gs mpx2010d gauge, axial pc mount 344f mpx2010gsx mpx2010d ordering information e small outline package (mpxv2010g series) device type options case no. mpx series order no. packing options marking ported elements gauge, side port, smt 1369 mpxv2010gp trays mpxv2010g differential, dual port, smt 1351 mpxv2010dp trays mpxv2010g f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
327 motorola sensor device data www.motorola.com/semiconductors "# !" " !!# ! ! the mpx2050 series device is a silicon piezoresistive pressure sensors providing a highly accurate and linear voltage output e directly proportional to the applied pressure. the sensor is a single, monolithic silicon diaphragm with the strain gauge and a thinfilm resistor network integrated onchip. the chip is laser trimmed for precise span and offset calibration and temperature compensation. features ? temperature compensated over 0 c to + 85 c ? unique silicon shear stress strain gauge ? easy to use chip carrier package options ? ratiometric to supply voltage ? differential and gauge options ? 0.25% linearity (mpx2050) application examples ? pump/motor controllers ? robotics ? level indicators ? medical diagnostics ? pressure switching ? noninvasive blood pressure measurement figure 1 shows a block diagram of the internal circuitry on the standalone pressure sensor chip. figure 1. temperature compensated pressure sensor schematic v s 3 sensing element thin film temperature compensation and calibration circuitry 2 4 v out+ v out 1 gnd voltage output versus applied differential pressure the differential voltage output of the sensor is directly proportional to the differential pressure applied. the output voltage of the differential or gauge sensor increases with increasing pressure applied to the pressure side (p1) relative to the vacuum side (p2). similarly, output voltage increases as increasing vacuum is applied to the vacuum side (p2) relative to the pressure side (p1). semiconductor technical data
0 to 50 kpa (0 to 7.25 psi) 40 mv full scale span (typical) pin number 1 2 gnd +v out 3 4 v s v out note: pin 1 is noted by the notch in the lead. mpx2050gp case 344b mpx2050gsx case 344f mpx2050d case 344 mpx2050dp case 344c rev 8 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

328 motorola sensor device data www.motorola.com/semiconductors maximum ratings (note) rating symbol value unit maximum pressure (p1 > p2) p max 200 kpa storage temperature t stg 40 to +125 c operating temperature t a 40 to +125 c note: exposure beyond the specified limits may cause permanent damage or degradation to the device. operating characteristics (v s = 10 vdc, t a = 25 c unless otherwise noted, p1 > p2) characteristic symbol min typ max unit pressure range (1) p op 0 e 50 kpa supply voltage (2) v s e 10 16 vdc supply current i o e 6.0 e madc full scale span (3) mpx2050 v fss 38.5 40 41.5 mv offset (4) mpx2050 v off 1.0 e 1.0 mv sensitivity d v/ d p e 0.8 e mv/kpa linearity (5) mpx2050 e 0.25 e 0.25 %v fss pressure hysteresis (5) (0 to 50 kpa) e e 0.1 e %v fss temperature hysteresis (5) ( 40 c to +125 c) e e 0.5 e %v fss temperature effect on full scale span (5) tcv fss 1.0 e 1.0 %v fss temperature effect on offset (5) tcv off 1.0 e 1.0 mv input impedance z in 1000 e 2500 w output impedance z out 1400 e 3000 w response time (6) (10% to 90%) t r e 1.0 e ms warmup e e 20 e ms offset stability (7) e e 0.5 e %v fss notes: 1. 1.0 kpa (kilopascal) equals 0.145 psi. 2. device is ratiometric within this specified excitation range. operating the device above the specified excitation range may i nduce additional error due to device selfheating. 3. full scale span (v fss ) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 4. offset (v off ) is defined as the output voltage at the minimum rated pressure. 5. accuracy (error budget) consists of the following: ? linearity: output deviation from a straight line relationship with pressure, using end point method, over the specified pressure range. ? temperature hysteresis: output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. ? pressure hysteresis: output deviation at any pressure within the specified range, when this pressure is cycled to and from the minimum or maximum rated pressure, at 25 c. ? tcspan: output deviation at full rated pressure over the temperature range of 0 to 85 c, relative to 25 c. ? tcoffset: output deviation with minimum rated pressure applied, over the temperature range of 0 to 85 c, relative to 25 c. 6. response time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when s ubjected to a specified step change in pressure. 7. offset stability is the product's output deviation when subjected to 1000 hours of pulsed pressure, temperature cycling with bias test. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

329 motorola sensor device data www.motorola.com/semiconductors linearity linearity refers to how well a transducer's output follows the equation: v out = v off + sensitivity x p over the operating pressure range. there are two basic methods for calculating nonlinearity: (1) end point straight line fit (see figure 2) or (2) a least squares best line fit. while a least squares fit gives the abest caseo linearity error (lower numerical value), the calculations required are burdensome. conversely, an end point fit will give the aworst caseo error (often more desirable in error budget calculations) and the calculations are more straightforward for the user. motorola's specified pressure sensor linearities are based on the end point straight line method measured at the midrange pres- sure. figure 2. linearity specification comparison least square deviation relative voltage output pressure (% fullscale) 0 50 100 end point straight line fit exaggerated performance curve least squares fit straight line deviation offset onchip temperature compensation and calibration figure 3 shows the minimum, maximum and typical output characteristics of the mpx2050 series at 25 c. the output is directly proportional to the differential pressure and is essen- tially a straight line. the effects of temperature on fullscale span and offset are very small and are shown under operating characteris- tics. figure 3. output versus pressure differential figure 4. crosssectional diagram (not to scale) output (mvdc) kpa psi 40 35 30 25 15 10 5 0 5 0 12.5 1.8 25 3.6 37.5 5.4 50 7.25 span range (typ) offset (typ) 20 silicone die coat wire bond lead frame die stainless steel metal cover epoxy case rtv die bond p1 p2 max typ min v s = 10 vdc t a = 25 c mpx2050 p1 > p2 figure 4 illustrates the differential or gauge configuration in the basic chip carrier (case 344). a silicone gel isolates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the silicon diaphragm. the mpx2050 series pressure sensor operating charac- teristics and internal reliability and qualification tests are based on use of dry air as the pressure media. media other than dry air may have adverse effects on sensor perfor- mance and long term reliability. contact the factory for in- formation regarding media compatibility in your application. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

330 motorola sensor device data www.motorola.com/semiconductors pressure (p1)/vacuum (p2) side identification table motorola designates the two sides of the pressure sensor as the pressure (p1) side and the vacuum (p2) side. the pressure (p1) side is the side containing the silicone gel which isolates the die. the motorola mpx pressure sensor is designed to operate with positive differential pressure applied, p1 > p2. the pressure (p1) side may be identified by using the table below: part number case type pressure (p1) side identifier mpx2050d 344 stainless steel cap mpx2050dp 344c side with part marking mpx2050gp 344b side with port attached mpx2050gsx 344f side with port attached ordering information mpx2050 series pressure sensors are available in differential and gauge configurations. devices are available in the basic element package or with pressure port fittings which provide printed circuit board mounting ease and barbed hose pressure connections. mpx series device type options case type order number device marking basic element differential 344 mpx2050d mpx2050d ported elements differential, dual port 344c mpx2050dp mpx2050dp gauge 344b mpx2050gp mpx2050gp gauge axial pc mount 344f mpx2050gsx mpx2050d f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
331 motorola sensor device data www.motorola.com/semiconductors " "#%&# !" $% #% ! #$$&# $!#$ the mpx2053/mpxv2053g device is a silicon piezoresistive pressure sensor providing a highly accurate and linear voltage output e directly proportional to the applied pressure. the sensor is a single, monolithic silicon diaphragm with the strain gauge and a thinfilm resistor network integrated onchip. the chip is laser trimmed for precise span and offset calibration and temperature compensation. features ? temperature compensated over 0 c to + 85 c ? easytouse chip carrier package options ? ratiometric to supply voltage ? differential and gauge options application examples ? pump/motor controllers ? robotics ? level indicators ? medical diagnostics ? pressure switching ? noninvasive blood pressure measurement figure 1 shows a block diagram of the internal circuitry on the standalone pressure sensor chip. figure 1. temperature compensated pressure sensor schematic v s 3 sensing element thin film temperature compensation and calibration circuitry 2 4 v out+ v out 1 gnd voltage output versus applied differential pressure the differential voltage output of the sensor is directly proportional to the differential pressure applied. the output voltage of the differential or gauge sensor increases with increasing pressure applied to the pressure side (p1) relative to the vacuum side (p2). similarly, output voltage increases as increasing vacu- um is applied to the vacuum side (p2) relative to the pressure side (p1). preferred devices are motorola recommended choices for future use and best overall value. replaces mpx2050/d semiconductor technical data

0 to 50 kpa (0 to 7.25 psi) 40 mv full scale span (typical) motorola preferred device small outline package surface mount unibody package mpx2053gp case 344b mpx2053gsx case 344f pin number note: pin 1 is noted by the notch in the lead. 1 2 3 gnd +v out v s 5 6 7 n/c n/c n/c 4v out 8 n/c mpx2053d case 344 mpx2053dp case 344c mpxv2053dp case 1351 mpxv2053gp case 1369 pin number 1 2 gnd +v out 3 4 v s v out note: pin 1 is noted by the notch in the lead. mpx2053gvp case 344d rev 3 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

332 motorola sensor device data www.motorola.com/semiconductors maximum ratings (note) rating symbol value unit maximum pressure (p1 > p2) p max 200 kpa storage temperature t stg 40 to +125 c operating temperature t a 40 to +125 c note: exposure beyond the specified limits may cause permanent damage or degradation to the device. operating characteristics (v s = 10 vdc, t a = 25 c unless otherwise noted, p1 > p2) characteristic symbol min typ max unit pressure range (1) p op 0 e 50 kpa supply voltage (2) v s e 10 16 vdc supply current i o e 6.0 e madc full scale span (3) v fss 38.5 40 41.5 mv offset (4) v off 1.0 e 1.0 mv sensitivity d v/ d p e 0.8 e mv/kpa linearity (5) e 0.6 e 0.4 %v fss pressure hysteresis (5) (0 to 50 kpa) e e 0.1 e %v fss temperature hysteresis (5) ( 40 c to +125 c) e e 0.5 e %v fss temperature effect on full scale span (5) tcv fss 2.0 e 2.0 %v fss temperature effect on offset (5) tcv off 1.0 e 1.0 mv input impedance z in 1000 e 2500 w output impedance z out 1400 e 3000 w response time (6) (10% to 90%) t r e 1.0 e ms warmup e e 20 e ms offset stability (7) e e 0.5 e %v fss notes: 1. 1.0 kpa (kilopascal) equals 0.145 psi. 2. device is ratiometric within this specified excitation range. operating the device above the specified excitation range may induce additional error due to device selfheating. 3. full scale span (v fss ) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 4. offset (v off ) is defined as the output voltage at the minimum rated pressure. 5. accuracy (error budget) consists of the following: ? linearity: output deviation from a straight line relationship with pressure, using end point method, over the specified pressure range. ? temperature hysteresis: output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. ? pressure hysteresis: output deviation at any pressure within the specified range, when this pressure is cycled to and from the minimum or maximum rated pressure, at 25 c. ? tcspan: output deviation at full rated pressure over the temperature range of 0 to 85 c, relative to 25 c. ? tcoffset: output deviation with minimum rated pressure applied, over the temperature range of 0 to 85 c, relative to 25 c. 6. response time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when s ubjected to a specified step change in pressure. 7. offset stability is the product's output deviation when subjected to 1000 hours of pulsed pressure, temperature cycling with bias test. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

333 motorola sensor device data www.motorola.com/semiconductors linearity linearity refers to how well a transducer's output follows the equation: v out = v off + sensitivity x p over the operating pressure range. there are two basic methods for calculating nonlinearity: (1) end point straight line fit (see figure 2) or (2) a least squares best line fit. while a least squares fit gives the abest caseo linearity error (lower numerical value), the calculations required are burdensome. conversely, an end point fit will give the aworst caseo error (often more desirable in error budget calculations) and the cal- culations are more straightforward for the user. motorola's specified pressure sensor linearities are based on the end point straight line method measured at the midrange pressure. figure 2. linearity specification comparison least square deviation relative voltage output pressure (% fullscale) 0 50 100 end point straight line fit exaggerated performance curve least squares fit straight line deviation offset onchip temperature compensation and calibration figure 3 shows the minimum, maximum and typical output characteristics of the mpx2053/mpxv2053g series at 25 c. the output is directly proportional to the differential pressure and is essentially a straight line. the effects of temperature on fullscale span and offset are very small and are shown under operating characteris- tics. figure 3. output versus pressure differential figure 4. crosssectional diagram (not to scale) output (mvdc) kpa psi 40 35 30 25 15 10 5 0 5 0 12.5 1.8 25 3.6 37.5 5.4 50 7.25 span range (typ) offset (typ) 20 silicone die coat wire bond lead frame die stainless steel metal cover epoxy case rtv die bond p1 p2 max typ min v s = 10 vdc t a = 25 c mpx2053 p1 > p2 figure 4 illustrates the differential or gauge configuration in the basic chip carrier (case 344). a silicone gel isolates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the silicon diaphragm. the mpx2053/mpxv2053g series pressure sensor oper- ating characteristics and internal reliability and qualification tests are based on use of dry air as the pressure media. me- dia other than dry air may have adverse effects on sensor performance and long term reliability. contact the factory for information regarding media compatibility in your application. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

334 motorola sensor device data www.motorola.com/semiconductors pressure (p1)/vacuum (p2) side identification table motorola designates the two sides of the pressure sensor as the pressure (p1) side and the vacuum (p2) side. the pressure (p1) side is the side containing the silicone gel which isolates the die. the motorola mpx pressure sensor is designed to operate with positive differential pressure applied, p1 > p2. the pressure (p1) side may be identified by using the table below: part number case type pressure (p1) side identifier mpx2053d 344 c stainless steel cap mpx2053dp 344c side with part marking mpx2053gp 344b side with port attached mpx2053gsx 344f side with port attached mpx2053gvp 344d stainless steel cap mpxv2053gp 1369 side with port attached mpxv2053dp 1351 side with part marking ordering information e unibody package (mpx2053 series) mpx series device type options case type order number device marking basic element differential 344 mpx2053d mpx2053d ported elements differential, dual port 344c mpx2053dp mpx2053dp gauge 344b mpx2053gp mpx2053gp gauge, axial pc mount 344f mpx2053gsx mpx2053d gauge, vacuum 344d mpx2053gvp mpx2053gvp ordering information e small outline package (mpxv2053g series) device type options case no. mpx series order no. packing options marking ported elements gauge, side port, smt 1369 mpxv2053gp trays mpxv2053g differential, dual port, smt 1351 mpxv2053dp trays mpxv2053g f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
335 motorola sensor device data www.motorola.com/semiconductors "# !" " !!# ! ! the mpx2100 series device is a silicon piezoresistive pressure sensor providing a highly accurate and linear voltage output e directly proportional to the applied pressure. the sensor is a single, monolithic silicon diaphragm with the strain gauge and a thinfilm resistor network integrated onchip. the chip is laser trimmed for precise span and offset calibration and temperature compensation. features ? temperature compensated over 0 c to + 85 c ? easytouse chip carrier package options ? available in absolute, differential and gauge configurations ? ratiometric to supply voltage ? 0.25% linearity (mpx2100d) application examples ? pump/motor controllers ? robotics ? level indicators ? medical diagnostics ? pressure switching ? barometers ? altimeters figure 1 illustrates a block diagram of the internal circuitry on the standalone pressure sensor chip. figure 1. temperature compensated pressure sensor schematic v s 3 sensing element thin film temperature compensation and calibration circuitry 2 4 v out+ v out 1 gnd voltage output versus applied differential pressure the differential voltage output of the sensor is directly proportional to the differential pressure applied. the absolute sensor has a builtin reference vacuum. the output voltage will decrease as vacuum, relative to ambient, is drawn on the pressure (p1) side. the output voltage of the differential or gauge sensor increases with increasing pressure applied to the pressure (p1) side relative to the vacuum (p2) side. similarly, output voltage increases as increasing vacuum is applied to the vacuum (p2) side relative to the pressure (p1) side. semiconductor technical data
0 to 100 kpa (0 to 14.5 psi) 40 mv full scale span (typical) unibody package mpx2100ap/gp case 344b mpx2100asx/gsx case 344f mpx2100a/d case 344 mpx2100dp case 344c pin number 1 2 gnd +v out 3 4 v s v out note: pin 1 is noted by the notch in the lead. rev 9 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

336 motorola sensor device data www.motorola.com/semiconductors maximum ratings (note) rating symbol value unit maximum pressure (p1 > p2) p max 400 kpa storage temperature t stg 40 to +125 c operating temperature t a 40 to +125 c note: exposure beyond the specified limits may cause permanent damage or degradation to the device. operating characteristics (v s = 10 vdc, t a = 25 c unless otherwise noted, p1 > p2) characteristic symbol min typ max unit pressure range (1) p op 0 e 100 kpa supply voltage (2) v s e 10 16 vdc supply current i o e 6.0 e madc full scale span (3) mpx2100a, mpx2100d v fss 38.5 40 41.5 mv offset (4) mpx2100d mpx2100a series v off 1.0 2.0 e e 1.0 2.0 mv sensitivity d v/ d p e 0.4 e mv/kpa linearity (5) mpx2100d series mpx2100a series e e 0.25 1.0 e e 0.25 1.0 %v fss pressure hysteresis (5) (0 to 100 kpa) e e 0.1 e %v fss temperature hysteresis (5) ( 40 c to +125 c) e e 0.5 e %v fss temperature effect on full scale span (5) tcv fss 1.0 e 1.0 %v fss temperature effect on offset (5) tcv off 1.0 e 1.0 mv input impedance z in 1000 e 2500 w output impedance z out 1400 e 3000 w response time (6) (10% to 90%) t r e 1.0 e ms warmup e e 20 e ms offset stability (7) e e 0.5 e %v fss notes: 1. 1.0 kpa (kilopascal) equals 0.145 psi. 2. device is ratiometric within this specified excitation range. operating the device above the specified excitation range may i nduce additional error due to device selfheating. 3. full scale span (v fss ) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 4. offset (v off ) is defined as the output voltage at the minimum rated pressure. 5. accuracy (error budget) consists of the following: ? linearity: output deviation from a straight line relationship with pressure, using end point method, over the specified pressure range. ? temperature hysteresis: output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. ? pressure hysteresis: output deviation at any pressure within the specified range, when this pressure is cycled to and from the minimum or maximum rated pressure, at 25 c. ? tcspan: output deviation at full rated pressure over the temperature range of 0 to 85 c, relative to 25 c. ? tcoffset: output deviation with minimum rated pressure applied, over the temperature range of 0 to 85 c, relative to 25 c. 6. response time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when s ubjected to a specified step change in pressure. 7. offset stability is the product's output deviation when subjected to 1000 hours of pulsed pressure, temperature cycling with bias test. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

337 motorola sensor device data www.motorola.com/semiconductors linearity linearity refers to how well a transducer's output follows the equation: v out = v off + sensitivity x p over the operating pressure range. there are two basic methods for calculating nonlinearity: (1) end point straight line fit (see figure 2) or (2) a least squares best line fit. while a least squares fit gives the abest caseo linearity error (lower numerical value), the calculations required are burdensome. conversely, an end point fit will give the aworst caseo error (often more desirable in error budget calculations) and the calculations are more straightforward for the user. motorola's specified pressure sensor linearities are based on the end point straight line method measured at the midrange pressure. figure 2. linearity specification comparison least square deviation relative voltage output pressure (% fullscale) 0 50 100 end point straight line fit exaggerated performance curve least squares fit straight line deviation offset onchip temperature compensation and calibration figure 3 shows the output characteristics of the mpx2100 series at 25 c. the output is directly proportional to the differential pressure and is essentially a straight line. the effects of temperature on full scale span and offset are very small and are shown under operating characteris- tics. figure 3. output versus pressure differential figure 4. crosssectional diagrams (not to scale) output (mvdc) kpa psi 40 35 30 25 15 10 5 0 5 025 3.62 50 7.25 75 10.87 100 14.5 span range (typ) offset (typ) 20 typ min v s = 10 vdc t a = 25 c p1 > p2 max silicone gel die coat wire bond lead frame differential/gauge die stainless steel metal cover epoxy case differential/gauge element die bond silicone gel die coat wire bond lead frame absolute die stainless steel metal cover epoxy case die bond absolute element p1 p2 p1 p2 figure 4 illustrates the absolute sensing configuration (right) and the differential or gauge configuration in the basic chip carrier (case 344). a silicone gel isolates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the silicon diaphragm. the mpx2100 series pressure sensor operating charac- teristics and internal reliability and qualification tests are based on use of dry air as the pressure media. media other than dry air may have adverse effects on sensor perfor- mance and long term reliability. contact the factory for in- formation regarding media compatibility in your application. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

338 motorola sensor device data www.motorola.com/semiconductors pressure (p1)/vacuum (p2) side identification table motorola designates the two sides of the pressure sensor as the pressure (p1) side and the vacuum (p2) side. the pressure (p1) side is the side containing the silicone gel which isolates the die. the differential or gauge sensor is designed to operate with positive differential pressure applied, p1 > p2. the absolute sensor is designed for vacuum applied to p1 side. the pressure (p1) side may be identified by using the table below: part number case type pressure (p1) side identifier mpx2100a mpx2100d 344 stainless steel cap mpx2100dp 344c side with part marking mpx2100ap mpx2100gp 344b side with port attached mpx2100asx mpx2100gsx 344f side with port attached ordering information mpx2100 series pressure sensors are available in absolute, differential and gauge configurations. devices are available in the basic element package or with pressure port fittings which provide printed circuit board mounting ease and barbed hose pressure connections. mpx series device type options case type order number device marking basic element absolute, differential 344 mpx2100a mpx2100d mpx2100a mpx2100d ported elements differential, dual port 344c mpx2100dp mpx2100dp absolute, gauge 344b mpx2100ap mpx2100gp mpx2100ap mpx2100gp absolute, gauge axial 344f mpx2100asx mpx2100gsx mpx2100a mpx2100d f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
339 motorola sensor device data www.motorola.com/semiconductors ! !"$%" !#$ "$ "##%" # "# the mpx2102/mpxv2102g series device is a silicon piezoresistive pressure sensor providing a highly accurate and linear voltage output e directly proportional to the applied pressure. the sensor is a single, monolithic silicon diaphragm with the strain gauge and a thinfilm resistor network integrated onchip. the chip is laser trimmed for precise span and offset calibration and temperature compensation. features ? temperature compensated over 0 c to + 85 c ? easytouse chip carrier package options ? available in absolute, differential and gauge con- figurations ? ratiometric to supply voltage application examples ? pump/motor controllers ? robotics ? level indicators ? medical diagnostics ? pressure switching ? barometers ? altimeters figure 1 illustrates a block diagram of the internal circuitry on the standalone pressure sensor chip. figure 1. temperature compensated pressure sensor schematic v s 3 sensing element thin film temperature compensation and calibration circuitry 2 4 v out+ v out 1 gnd voltage output versus applied differential pressure the differential voltage output of the sensor is directly proportional to the differential pressure applied. the absolute sensor has a builtin reference vacu- um. the output voltage will decrease as vacuum, relative to ambient, is drawn on the pressure (p1) side. the output voltage of the differential or gauge sensor increases with increasing pressure applied to the pressure (p1) side relative to the vacuum (p2) side. similarly, output voltage increases as increasing vacu- um is applied to the vacuum (p2) side relative to the pressure (p1) side. preferred devices are motorola recommended choices for future use and best overall value. semiconductor technical data
0 to 100 kpa (0 to 14.5 psi) 40 mv full scale span (typical) motorola preferred device small outline package surface mount unibody package mpx2102ap/gp case 344b mpx2102asx/gsx case 344f pin number note: pin 1 is noted by the notch in the lead. 1 2 3 gnd +v out v s 5 6 7 n/c n/c n/c 4v out 8 n/c mpx2102a/d case 344 mpx2102dp case 344c mpxv2102dp case 1351 mpxv2102gp case 1369 pin number 1 2 gnd +v out 3 4 v s v out note: pin 1 is noted by the notch in the lead. mpx2102gvp case 344d rev 2 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

340 motorola sensor device data www.motorola.com/semiconductors maximum ratings (note) rating symbol value unit maximum pressure (p1 > p2) p max 400 kpa storage temperature t stg 40 to +125 c operating temperature t a 40 to +125 c note: exposure beyond the specified limits may cause permanent damage or degradation to the device. operating characteristics (v s = 10 vdc, t a = 25 c unless otherwise noted, p1 > p2) characteristic symbol min typ max unit pressure range (1) p op 0 e 100 kpa supply voltage (2) v s e 10 16 vdc supply current i o e 6.0 e madc full scale span (3) v fss 38.5 40 41.5 mv offset (4) mpx2102d series mpx2102a series v off 1.0 2.0 e e 1.0 2.0 mv sensitivity d v/ d p e 0.4 e mv/kpa linearity (5) mpx2102d series mpx2102a series e e 0.6 1.0 e e 0.4 1.0 %v fss pressure hysteresis (5) (0 to 100 kpa) e e 0.1 e %v fss temperature hysteresis (5) ( 40 c to +125 c) e e 0.5 e %v fss temperature effect on full scale span (5) tcv fss 2.0 e 2.0 %v fss temperature effect on offset (5) tcv off 1.0 e 1.0 mv input impedance z in 1000 e 2500 w output impedance z out 1400 e 3000 w response time (6) (10% to 90%) t r e 1.0 e ms warmup e e 20 e ms offset stability (7) e e 0.5 e %v fss notes: 1. 1.0 kpa (kilopascal) equals 0.145 psi. 2. device is ratiometric within this specified excitation range. operating the device above the specified excitation range may i nduce additional error due to device selfheating. 3. full scale span (v fss ) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 4. offset (v off ) is defined as the output voltage at the minimum rated pressure. 5. accuracy (error budget) consists of the following: ? linearity: output deviation from a straight line relationship with pressure, using end point method, over the specified pressure range. ? temperature hysteresis: output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. ? pressure hysteresis: output deviation at any pressure within the specified range, when this pressure is cycled to and from the minimum or maximum rated pressure, at 25 c. ? tcspan: output deviation at full rated pressure over the temperature range of 0 to 85 c, relative to 25 c. ? tcoffset: output deviation with minimum rated pressure applied, over the temperature range of 0 to 85 c, relative to 25 c. 6. response time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when s ubjected to a specified step change in pressure. 7. offset stability is the product's output deviation when subjected to 1000 hours of pulsed pressure, temperature cycling with bias test. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

341 motorola sensor device data www.motorola.com/semiconductors linearity linearity refers to how well a transducer's output follows the equation: v out = v off + sensitivity x p over the operating pressure range. there are two basic methods for calculating nonlinearity: (1) end point straight line fit (see figure 2) or (2) a least squares best line fit. while a least squares fit gives the abest caseo linearity error (lower numerical value), the calculations required are burdensome. conversely, an end point fit will give the aworst caseo error (often more desirable in error budget calculations) and the calculations are more straightforward for the user. motorola's specified pressure sensor linearities are based on the end point straight line method measured at the midrange pressure. figure 2. linearity specification comparison least square deviation relat i ve voltage out p ut pressure (% fullscale) 0 50 100 end point straight line fit exaggerated performance curve least squares fit straight line deviation offset onchip temperature compensation and calibration figure 3 shows the output characteristics of the mpx2102/mpxv2102g series at 25 c. the output is directly proportional to the differential pressure and is essentially a straight line. the effects of temperature on full scale span and offset are very small and are shown under operating characteris- tics. figure 3. output versus pressure differential figure 4. crosssectional diagrams (not to scale) output (mvdc) kpa psi 40 35 30 25 15 10 5 0 5 025 3.62 50 7.25 75 10.87 100 14.5 span range (typ) offset (typ) 20 typ min v s = 10 vdc t a = 25 c p1 > p2 max silicone gel die coat wire bond lead frame differential/gauge die stainless steel metal cover epoxy case differential/gauge element die bond silicone gel die coat wire bond lead frame absolute die stainless steel metal cover epoxy case die bond absolute element p1 p2 p1 p2 figure 4 illustrates the absolute sensing configuration (right) and the differential or gauge configuration in the basic chip carrier (case 344). a silicone gel isolates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the silicon diaphragm. the mpx2102/mpxv2102g series pressure sensor oper- ating characteristics and internal reliability and qualification tests are based on use of dry air as the pressure media. me- dia other than dry air may have adverse effects on sensor performance and long term reliability. contact the factory for information regarding media compatibility in your application. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

342 motorola sensor device data www.motorola.com/semiconductors pressure (p1)/vacuum (p2) side identification table motorola designates the two sides of the pressure sensor as the pressure (p1) side and the vacuum (p2) side. the pressure (p1) side is the side containing the silicone gel which isolates the die. the differential or gauge sensor is designed to operate with positive differential pressure applied, p1 > p2. the absolute sensor is designed for vacuum applied to p1 side. the pressure (p1) side may be identified by using the table below: part number case type pressure (p1) side identifier mpx2102a mpx2102d 344 stainless steel cap mpx2102dp 344c side with part marking mpx2102ap mpx2102gp 344b side with port attached mpx2102gvp 344d stainless steel cap mpx2102asx mpx2102gsx 344f side with port attached mpxv2102gp 1369 side with port attached mpxv2102dp 1351 side with part marking ordering information e unibody package (mpx2102 series) mpx series device type options case type order number device marking basic element absolute, differential 344 mpx2102a mpx2102d mpx2102a mpx2102d ported elements differential, dual port 344c mpx2102dp mpx2102dp absolute, gauge 344b mpx2102ap mpx2102gp mpx2102ap mpx2102gp absolute, gauge axial 344f mpx2102asx mpx2102gsx mpx2102a mpx2102d gauge, vacuum 344d mpx2102gvp mpx2102gvp ordering information e small outline package (mpxv2102g series) device type options case no. mpx series order no. packing options marking ported elements gauge, side port, smt 1369 mpxv2102gp trays mpxv2102g differential, dual port, smt 1351 mpxv2102dp trays mpxv2102g f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
343 motorola sensor device data www.motorola.com/semiconductors ! ! the mpx2200 series device is a silicon piezoresistive pressure sensor providing a highly accurate and linear voltage output e directly proportional to the applied pressure. the sensor is a single monolithic silicon diaphragm with the strain gauge and a thinfilm resistor network integrated onchip. the chip is laser trimmed for precise span and offset calibration and temperature compensation. they are designed for use in applications such as pump/motor controllers, robotics, level indicators, medical diagnostics, pressure switching, barometers, altimeters, etc. features ? temperature compensated over 0 c to + 85 c ? 0.25% linearity (mpx2200d) ? easytouse chip carrier package options ? available in absolute, differential and gauge configurations application examples ? pump/motor controllers ? robotics ? level indicators ? medical diagnostics ? pressure switching ? barometers ? altimeters figure 1 illustrates a block diagram of the internal circuitry on the standalone pressure sensor chip. figure 1. temperature compensated pressure sensor schematic v s 3 sensing element thin film temperature compensation and calibration circuitry 2 4 v out+ v out 1 gnd voltage output versus applied differential pressure the differential voltage output of the sensor is directly proportional to the differential pressure applied. the absolute sensor has a builtin reference vacuum. the output voltage will decrease as vacuum, relative to ambient, is drawn on the pressure (p1) side. the output voltage of the differential or gauge sensor increases with increasing pressure applied to the pressure (p1) side relative to the vacuum (p2) side. similarly, output voltage increases as increasing vacuum is applied to the vacuum (p2) side relative to the pressure (p1) side.
semiconductor technical data 0 to 200 kpa (0 to 29 psi) 40 mv full scale span (typical) unibody package mpx2200ap/gp case 344b mpx2200gvp case 344d mpx2200a/d case 344 mpx2200dp case 344c pin number 1 2 gnd +v out 3 4 v s v out note: pin 1 is noted by the notch in the lead. rev 9 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

344 motorola sensor device data www.motorola.com/semiconductors maximum ratings (note) rating symbol value unit maximum pressure (p1 > p2) p max 800 kpa storage temperature t stg 40 to +125 c operating temperature t a 40 to +125 c note: exposure beyond the specified limits may cause permanent damage or degradation to the device. operating characteristics (v s = 10 vdc, t a = 25 c unless otherwise noted, p1 > p2) characteristics symbol min typ max unit pressure range (1) p op 0 e 200 kpa supply voltage v s e 10 16 vdc supply current i o e 6.0 e madc full scale span (3) v fss 38.5 40 41.5 mv offset (4) v off 1.0 e 1.0 mv sensitivity d v/ d p e 0.2 e mv/kpa linearity (5) mpx2200d series mpx2200a series e 0.25 1.0 e e 0.25 1.0 %v fss pressure hysteresis (5) (0 to 200 kpa) e e 0.1 e %v fss temperature hysteresis (5) ( 40 c to +125 c) e e 0.5 e %v fss temperature effect on full scale span (5) tcv fss 1.0 e 1.0 %v fss temperature effect on offset (5) tcv off 1.0 e 1.0 mv input impedance z in 1300 e 2500 w output impedance z out 1400 e 3000 w response time (6) (10% to 90%) t r e 1.0 e ms warmup e e 20 e ms offset stability (7) e e 0.5 e %v fss notes: 1. 1.0 kpa (kilopascal) equals 0.145 psi. 2. device is ratiometric within this specified excitation range. operating the device above the specified excitation range may induce additional error due to device selfheating. 3. full scale span (v fss ) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 4. offset (v off ) is defined as the output voltage at the minimum rated pressure. 5. accuracy (error budget) consists of the following: ? linearity: output deviation from a straight line relationship with pressure, using end point method, over the specified pressure range. ? temperature hysteresis: output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. ? pressure hysteresis: output deviation at any pressure within the specified range, when this pressure is cycled to and from the minimum or maximum rated pressure, at 25 c. ? tcspan: output deviation at full rated pressure over the temperature range of 0 to 85 c, relative to 25 c. ? tcoffset: output deviation with minimum rated pressure applied, over the temperature range of 0 to 85 c, relative to 25 c. 6. response time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when s ubjected to a specified step change in pressure. 7. offset stability is the product's output deviation when subjected to 1000 hours of pulsed pressure, temperature cycling with bias test. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

345 motorola sensor device data www.motorola.com/semiconductors linearity linearity refers to how well a transducer's output follows the equation: v out = v off + sensitivity x p over the operating pressure range. there are two basic methods for calculating nonlinearity: (1) end point straight line fit (see figure 2) or (2) a least squares best line fit. while a least squares fit gives the abest caseo linearity error (lower numerical value), the calculations required are burdensome. conversely, an end point fit will give the aworst caseo error (often more desirable in error budget calculations) and the calculations are more straightforward for the user. motoro- la's specified pressure sensor linearities are based on the end point straight line method measured at the midrange pressure. figure 2. linearity specification comparison least square deviation relative voltage output pressure (% fullscale) 0 50 100 end point straight line fit exaggerated performance curve least squares fit straight line deviation offset onchip temperature compensation and calibration figure 3 shows the output characteristics of the mpx2200 series at 25 c. the output is directly proportional to the dif- ferential pressure and is essentially a straight line. the effects of temperature on full scale span and offset are very small and are shown under operating characteristics. figure 3. output versus pressure differential figure 4. crosssectional diagrams (not to scale) 40 35 30 25 20 15 10 5 0 5 050 7.25 100 14.5 150 21.75 200 29 pressure output (mvdc) span range (typ) offset kpa psi v s = 10 vdc t a = 25 c p1 > p2 25 75 125 175 max typ min silicone gel die coat wire bond lead frame differential/gauge die stainless steel metal cover epoxy case differential/gauge element die bond silicone gel die coat wire bond lead frame absolute die stainless steel metal cover epoxy case die bond absolute element p1 p2 p1 p2 figure 4 illustrates an absolute sensing die (right) and the differential or gauge die in the basic chip carrier (case 344). a silicone gel isolates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the silicon diaphragm. the mpx2200 series pressure sensor operating charac- teristics and internal reliability and qualification tests are based on use of dry air as the pressure media. media other than dry air may have adverse effects on sensor perfor- mance and long term reliability. contact the factory for in- formation regarding media compatibility in your application. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

346 motorola sensor device data www.motorola.com/semiconductors pressure (p1)/vacuum (p2) side identification table motorola designates the two sides of the pressure sensor as the pressure (p1) side and the vacuum (p2) side. the pressure (p1) side is the side containing the silicone gel which isolates the die from the environment. the differential or gauge sensor is designed to operate with positive differen- tial pressure applied, p1 > p2. the absolute sensor is designed for vacuum applied to p1 side. the pressure (p1) side may be identified by using the table below: part number case type pressure (p1) side identifier mpx2200a mpx2200d 344 stainless steel cap mpx2200dp 344c side with part marking mpx2200ap mpx2200gp 344b side with port attached mpx2200gvp 344d stainless steel cap ordering information mpx2200 series pressure sensors are available in absolute, differential and gauge configurations. devices are available in the basic element package or with pressure port fittings which provide printed circuit board mounting ease and barbed hose pressure connections. mpx series device type options case type order number device marking basic element absolute, differential 344 mpx2200a mpx2200d mpx2200a mpx2200d ported elements differential 344c mpx2200dp mpx2200dp absolute, gauge 344b mpx2200ap mpx2200gp mpx2200ap mpx2200gp gauge, vacuum 344d mpx2200gvp mpx2200gvp f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
347 motorola sensor device data www.motorola.com/semiconductors "# !" " !!# ! ! the mpx2202/mpxv2202g device series is a silicon piezoresistive pressure sensor providing a highly accurate and linear voltage output e directly proportional to the applied pressure. the sensor is a single monolithic silicon diaphragm with the strain gauge and a thinfilm resistor network integrated onchip. the chip is laser trimmed for precise span and offset calibration and temperature compensation. they are designed for use in applications such as pump/motor controllers, robotics, level indicators, medical diagnostics, pressure switching, barometers, altimeters, etc. features ? temperature compensated over 0 c to + 85 c ? easytouse chip carrier package options ? available in absolute, differential and gauge con- figurations application examples ? pump/motor controllers ? robotics ? level indicators ? medical diagnostics ? pressure switching ? barometers ? altimeters figure 1 illustrates a block diagram of the internal circuitry on the standalone pressure sensor chip. figure 1. temperature compensated pressure sensor schematic v s 3 sensing element thin film temperature compensation and calibration circuitry 2 4 v out+ v out 1 gnd voltage output versus applied differential pressure the differential voltage output of the sensor is directly proportional to the differential pressure applied. the absolute sensor has a builtin reference vacu- um. the output voltage will decrease as vacuum, relative to ambient, is drawn on the pressure (p1) side. the output voltage of the differential or gauge sensor increases with increasing pressure applied to the pressure (p1) side relative to the vacuum (p2) side. similarly, output voltage increases as increasing vacu- um is applied to the vacuum (p2) side relative to the pressure (p1) side. preferred devices are motorola recommended choices for future use and best overall value. replaces mpx2200/d semiconductor technical data
0 to 200 kpa (0 to 29 psi) 40 mv full scale span (typical) motorola preferred device small outline package surface mount pin number note: pin 1 is noted by the notch in the lead. 1 2 3 gnd +v out v s 5 6 7 n/c n/c n/c 4v out 8 n/c mpxv2202dp case 1351 mpxv2202gp case 1369 unibody package mpx2202ap/gp case 344b mpx2202asx/gsx case 344f mpx2202a/d case 344 mpx2202dp case 344c pin number 1 2 gnd +v out 3 4 v s v out note: pin 1 is noted by the notch in the lead. mpx2202gvp case 344d rev 2 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

348 motorola sensor device data www.motorola.com/semiconductors maximum ratings (note) rating symbol value unit maximum pressure (p1 > p2) p max 800 kpa storage temperature t stg 40 to +125 c operating temperature t a 40 to +125 c note: exposure beyond the specified limits may cause permanent damage or degradation to the device. operating characteristics (v s = 10 vdc, t a = 25 c unless otherwise noted, p1 > p2) characteristics symbol min typ max unit pressure range (1) p op 0 e 200 kpa supply voltage v s e 10 16 vdc supply current i o e 6.0 e madc full scale span (3) v fss 38.5 40 41.5 mv offset (4) v off 1.0 e 1.0 mv sensitivity d v/ d p e 0.2 e mv/kpa linearity (5) mpx2202d series mpx2202a series e 0.6 1.0 e e 0.4 1.0 %v fss pressure hysteresis (5) (0 to 200 kpa) e e 0.1 e %v fss temperature hysteresis (5) ( 40 c to +125 c) e e 0.5 e %v fss temperature effect on full scale span (5) tcv fss 2.0 e 2.0 %v fss temperature effect on offset (5) tcv off 1.0 e 1.0 mv input impedance z in 1000 e 2500 w output impedance z out 1400 e 3000 w response time (6) (10% to 90%) t r e 1.0 e ms warmup e e 20 e ms offset stability (7) e e 0.5 e %v fss notes: 1. 1.0 kpa (kilopascal) equals 0.145 psi. 2. device is ratiometric within this specified excitation range. operating the device above the specified excitation range may i nduce additional error due to device selfheating. 3. full scale span (v fss ) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 4. offset (v off ) is defined as the output voltage at the minimum rated pressure. 5. accuracy (error budget) consists of the following: ? linearity: output deviation from a straight line relationship with pressure, using end point method, over the specified pressure range. ? temperature hysteresis: output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. ? pressure hysteresis: output deviation at any pressure within the specified range, when this pressure is cycled to and from the minimum or maximum rated pressure, at 25 c. ? tcspan: output deviation at full rated pressure over the temperature range of 0 to 85 c, relative to 25 c. ? tcoffset: output deviation with minimum rated pressure applied, over the temperature range of 0 to 85 c, relative to 25 c. 6. response time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when s ubjected to a specified step change in pressure. 7. offset stability is the product's output deviation when subjected to 1000 hours of pulsed pressure, temperature cycling with bias test. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

349 motorola sensor device data www.motorola.com/semiconductors linearity linearity refers to how well a transducer's output follows the equation: v out = v off + sensitivity x p over the operating pressure range. there are two basic methods for calculating nonlinearity: (1) end point straight line fit (see figure 2) or (2) a least squares best line fit. while a least squares fit gives the abest caseo linearity error (lower numerical value), the calculations required are burdensome. conversely, an end point fit will give the aworst caseo error (often more desirable in error budget calculations) and the calculations are more straightforward for the user. motorola's specified pressure sensor linearities are based on the end point straight line method measured at the midrange pressure. figure 2. linearity specification comparison least square deviation relative voltage output pressure (% fullscale) 0 50 100 end point straight line fit exaggerated performance curve least squares fit straight line deviation offset onchip temperature compensation and calibration figure 3 shows the output characteristics of the mpx2202/mpxv2202g series at 25 c. the output is directly proportional to the differential pressure and is essentially a straight line. the effects of temperature on full scale span and offset are very small and are shown under operating characteristics. figure 3. output versus pressure differential figure 4. crosssectional diagrams (not to scale) 40 35 30 25 20 15 10 5 0 5 050 7.25 100 14.5 150 21.75 200 29 pressure output (mvdc) span range (typ) offset kpa psi v s = 10 vdc t a = 25 c p1 > p2 25 75 125 175 max typ min silicone gel die coat wire bond lead frame differential/gauge die stainless steel metal cover epoxy case differential/gauge element die bond silicone gel die coat wire bond lead frame absolute die stainless steel metal cover epoxy case die bond absolute element p1 p2 p1 p2 figure 4 illustrates an absolute sensing die (right) and the differential or gauge die in the basic chip carrier (case 344). a silicone gel isolates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the silicon diaphragm. the mpx2202/mpxv2202g series pressure sensor oper- ating characteristics and internal reliability and qualification tests are based on use of dry air as the pressure media. me- dia other than dry air may have adverse effects on sensor performance and long term reliability. contact the factory for information regarding media compatibility in your application. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

350 motorola sensor device data www.motorola.com/semiconductors pressure (p1)/vacuum (p2) side identification table motorola designates the two sides of the pressure sensor as the pressure (p1) side and the vacuum (p2) side. the pressure (p1) side is the side containing the silicone gel which isolates the die from the environment. the differential or gauge sensor is designed to operate with positive differen- tial pressure applied, p1 > p2. the absolute sensor is designed for vacuum applied to p1 side. the pressure (p1) side may be identified by using the table below: part number case type pressure (p1) side identifier mpx2202a mpx2202d 344 stainless steel cap mpx2202dp 344c side with part marking mpx2202ap mpx2202gp 344b side with port attached mpx2202gvp 344d stainless steel cap mpx2202asx mpx2202gsx 344f side with port attached mpxv2202gp 1369 side with port attached mpxv2202dp 1351 side with part marking ordering information e unibody package (mpx2202 series) mpx series device type options case type order number device marking basic element absolute, differential 344 mpx2202a mpx2202d mpx2202a mpx2202d ported elements differential, dual port 344c mpx2202dp mpx2202dp absolute, gauge 344b mpx2202ap mpx2202gp mpx2202ap mpx2202gp absolute, gauge axial 344f mpx2202asx mpx2202gsx mpx2202a mpx2202d gauge, vacuum 344d mpx2202gvp mpx2202gvp ordering information e small outline package (mpxv2202g series) device type options case no. mpx series order no. packing options marking ported elements gauge, side port, smt 1369 mpxv2202gp trays mpxv2202g differential, dual port, smt 1351 mpxv2202dp trays mpxv2202g f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
351 motorola sensor device data www.motorola.com/semiconductors " " ! motorola has developed a low cost, high volume, miniature pressure sensor package which is ideal as a submodule component or a disposable unit. the unique concept of the chip pak allows great flexibility in system design while allowing an economic solution for the designer. this new chip carrier package uses motorola's unique sensor die with its piezoresistive technology, along with the added feature of onchip, thinfilm temperature compensation and calibration. note: motorola is also offering the chip pak package in applicationspecific configurations, which will have an aspxo prefix, followed by a fourdigit number, unique to the specific customer. features ? low cost ? integrated temperature compensation and calibration ? ratiometric to supply voltage ? polysulfone case material (medical, class v approved) ? provided in easytouse tape and reel application examples ? medical diagnostics ? infusion pumps ? blood pressure monitors ? pressure catheter applications ? patient monitoring note: the die and wire bonds are exposed on the front side of the chip pak (pressure is applied to the backside of the device). front side die and wire protection must be provided in the customer's housing. use caution when handling the devices during all processes. motorola's mpx2300dt1/mpx2301dt1 pressure sen- sors have been designed for medical usage by combining the performance of motorola's shear stress pressure sensor design and the use of biomedically approved materials. materials with a proven history in medical situations have been chosen to provide a sensor that can be used with confidence in applications, such as invasive blood pressure monitoring. it can be sterilized using ethylene oxide. the portions of the pressure sensor that are required to be biomedically approved are the rigid housing and the gel coating. the rigid housing is molded from a white, medical grade polysulfone that has passed extensive biological testing including: tissue culture test, rabbit implant, hemolysis, intracutaneous test in rabbits, and system toxicity, usp. a silicone dielectric gel covers the silicon piezoresistive sensing element. the gel is a nontoxic, nonallergenic elasto- mer system which meets all usp xx biological testing class v requirements. the properties of the gel allow it to transmit pressure uniformly to the diaphragm surface, while isolating the internal electrical connections from the corrosive effects of fluids, such as saline solution. the gel provides electrical isolation sufficient to withstand defibrillation testing, as speci- fied in the proposed association for the advancement of medical instrumentation (aami) standard for blood pressure transducers. a biomedically approved opaque filler in the gel prevents bright operating room lights from affecting the per- formance of the sensor. the mpx2301dt1 is a reduced gel option. preferred devices are motorola recommended choices for future use and best overall value.
semiconductor technical data pressure sensors 0 to 300 mmhg (0 to 40 kpa) pin number mpx2300/1dt1 case 423a 1 2 v s s+ 3 4 s gnd motorola preferred device chip pak package rev 5 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

352 motorola sensor device data www.motorola.com/semiconductors maximum ratings (note) rating symbol value unit maximum pressure (backside) p max 125 psi storage temperature t stg 25 to + 85 c operating temperature t a + 15 to + 40 c note: exposure beyond the specified limits may cause permanent damage or degradation to the device. operating characteristics (v s = 6 vdc, t a = 25 c unless otherwise noted) characteristics symbol min typ max unit pressure range p op 0 e 300 mmhg supply voltage (7) v s e 6.0 10 vdc supply current i o e 1.0 e madc zero pressure offset v off 0.75 e 0.75 mv sensitivity e 4.95 5.0 5.05 m v/v/mmhg full scale span (1) v fss 2.976 3.006 3.036 mv linearity + hysteresis (2) e 1.5 e 1.5 %v fss accuracy (9) v s = 6 v, p = 101 to 200 mmhg e 1.5 e 1.5 % accuracy (9) v s = 6 v, p = 201 to 300 mmhg e 3.0 e 3.0 % temperature effect on sensitivity tcs 0.1 e + 0.1 %/ c temperature effect on full scale span (3) tcv fss 0.1 e + 0.1 %/ c temperature effect on offset (4) tcv off 9.0 e + 9.0 m v/ c input impedance z in 1800 e 4500 w output impedance z out 270 e 330 w r cal (150 k w ) (8) r cal 97 100 103 mmhg response time (5) (10% to 90%) t r e 1.0 e ms temperature error band e 0 e 85 c stability (6) e e 0.5 e %v fss notes: 1. measured at 6.0 vdc excitation for 100 mmhg pressure differential. v fss and fss are like terms representing the algebraic difference between full scale output and zero pressure offset. 2. maximum deviation from endpoint straight line fit at 0 and 200 mmhg. 3. slope of endpoint straight line fit to full scale span at 15 c and + 40 c relative to + 25 c. 4. slope of endpoint straight line fit to zero pressure offset at 15 c and + 40 c relative to + 25 c. 5. for a 0 to 300 mmhg pressure step change. 6. stability is defined as the maximum difference in output at any pressure within p op and temperature within +10 c to + 85 c after: a. 1000 temperature cycles, 40 c to +125 c. b. 1.5 million pressure cycles, 0 to 300 mmhg. 7. recommended voltage supply: 6 v 0.2 v, regulated. sensor output is ratiometric to the voltage supply. supply voltages above +10 v may induce additional error due to device selfheating. 8. offset measurement with respect to the measured sensitivity when a 150k ohm resistor is connected to v s and s+ output. 9. accuracy is calculated using the following equation: error p = {[v p offset)/(sens nom *v ex )]p}/p where: v p = actual output voltage at pressure p in microvolts ( m v) offset = voltage output at p = 0mmhg in microvolts ( m v) sens nom = nominal sensitivity = 5.01 m v/v/mmhg v ex = excitation voltage p = pressure applied to the device f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

353 motorola sensor device data www.motorola.com/semiconductors ordering information the mpx2300dt1/mpx2301dt1 silicon pressure sensors are available in tape and reel packaging. device type/order no. case no. device description marking mpx2300dt1 423a chip pak, full gel date code, lot id mpx2301dt1 423a chip pak, 1/3 gel date code, lot id packaging information reel size tape width quantity tape and reel 330 mm 24 mm 1000 pc/reel f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
354 motorola sensor device data www.motorola.com/semiconductors
" " !!# ! " "# !" " the mpx4080d series piezoresistive transducer is a stateoftheart monolithic silicon pressure sensor designed for a wide range of applications, but particularly those employing a microcontroller or microprocessor with a/d inputs. this patented, single element transducer c ombines advanced micromachining techniques, thinfilm metalliza- tion, and bipolar processing to provide an accurate, high level analog output signal that is proportional to the applied pressure. features ? 3.0% maximum error over 0 to 85 c ? ideally suited for microprocessor or microcontrollerbased systems ? temperature compensated from 40 to 105 c ? easytouse, durable epoxy unibody package figure 1 shows a block diagram of the internal circuitry integrated on the pressure sensor chip. v s sensing element gnd thin film temperature compensation and gain stage #1 gain stage #2 and ground reference shift circuitry pins 4, 5 and 6 are no connects figure 1. fully integrated pressure sensor schematic v out semiconductor technical data integrated pressure sensor 0 to 80 kpa (0 to 11.6 psi) 0.58 to 4.9 volts output note: pin 1 is the notched pin. pin number note: pins 4, 5, and 6 are internal device connections. do not connect to external circuitry or ground. pin 1 is noted by the notch in the lead. mpx4080d case 867 1 2 3 v out gnd v s 4 5 6 n/c n/c n/c unibody package rev 1 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
355 motorola sensor device data www.motorola.com/semiconductors maximum ratings (note) parametrics symbol value unit maximum pressure (p1 > p2) (p2 > p1) p max 400 400 kpa storage temperature t stg 40 to +125 c note: exposure beyond the specified limits may cause permanent damage or degradation to the device. operating characteristics (v s = 5.1 vdc, t a = 25 c unless otherwise noted, p1 > p2. decoupling circuit shown in figure 4 required to meet electrical specifications.) characteristic symbol min typ max unit pressure range (1) p op 0 e 80 kpa supply voltage (2) v s 4.85 5.1 5.35 vdc supply current i o e 7.0 10 madc minimum pressure offset (3) (0 to 85 c) @ v s = 5.1 volts v off 0.478 0.575 0.672 vdc full scale output (4) (0 to 85 c) @ v s = 5.1 volts v fso 4.772 4.900 5.020 vdc full scale span (5) (0 to 85 c) @ v s = 5.1 volts v fss e 4.325 e vdc accuracy (6) e e e 3.0 %v fss sensitivity v/p e 54 e mv/kpa notes: 1. 1.0kpa (kilopascal) equals 0.145 psi. 2. device is ratiometric within this specified excitation range. 3. offset (v off ) is defined as the output voltage at the minimum rated pressure. 4. full scale output (v fso ) is defined as the output voltage at the maximum or full rated pressure. 5. full scale span (v fss ) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 6. accuracy (error budget) consists of the following: ? linearity: output deviation from a straight line relationship with pressure over the specified pressure range. ? temperature hysteresis: output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. ? pressure hysteresis: output deviation at any pressure within the specified range, when this pressure is cycled to and from minimum or maximum rated pressure at 25 c. ? tcspan: output deviation over the temperature range of 0 to 85 c, relative to 25 c. ? tcoffset: output deviation with minimum pressure applied, over the temperature range of 0 to 85 c, relative to 25 c. ? variation from nominal: the variation from nominal values, for offset or full scale span, as a percent of v fss at 25 c. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
356 motorola sensor device data www.motorola.com/semiconductors onchip temperature compensation, calibration and signal conditioning figure 2. output versus pressure differential figure 2 shows the sensor output signal relative to differential pressure input. typical, minimum, and maximum output curves are shown for operation over a temperature range of 0 to 85 c using the decoupling circuit shown in figure 4. the output will saturate out- side of the specified pressure range. output (v) 5 4.5 4 3.5 3 pressure (kpa) typ max min 0 10 20 30 40 50 60 70 80 2.5 2 1.5 1 0.5 0 v s = 5.1 vdc t a = 25 c mpx4080 span range (typ) output range (typ) offset (typ) fluoro silicone gel die coat wire bond lead frame die stainless steel metal cover epoxy plastic case differential/gauge element die bond figure 3. crosssectional diagrams (not to scale) figure 3 illustrates the differential sensing chip in the basic chip carrier (case 867). a fluorosilicone gel isolates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the sensor dia- phragm. the mpx4080d pressure sensor operating character- istics, internal reliability, and qualification tests are based on use of dry air as the pressure media. media, other than dry air, may have adverse effects on sensor perfor- mance and longterm reliability. contact the factory for information regarding media compatibility in your applica- tion. figure 4 shows the recommended decoupling circuit for in- terfacing the output of the integrated sensor to the a/d input of a microprocessor or microcontroller. proper decoupling of the power supply is recommended. figure 4. recommended power supply decoupling and output filtering. for additional output filtering, please refer to application note an1646. 1.0 f ips 470 pf output vs 5 v 0.01 f gnd vout f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
357 motorola sensor device data www.motorola.com/semiconductors nominal transfer value: v out = v s (p x 0.01059 + 0.11280) +/ (pressure error x temp. mult. x 0.01059 x v s ) v s = 5.1 v 0.25v p kpa transfer function (mpx4080d) temperature error multiplier break points temp multiplier temperature in c 4.0 3.0 2.0 0.0 1.0 40 20 0 20 40 60 130 120 100 80 mpx4080d pressure error band pressure in kpa 3.0 2.0 1.0 1.0 2.0 3.0 0.0 0 20 40 60 80 100 120 pressure error (max) 0 to 6 kpa 1.8 kpa 0 to 60 kpa 1.5 kpa 60 to 80 kpa 2.3 kpa 40 3 0 to 85 1 +105 2 note: the temperature multiplier is a linear response from 0 to 40 c and from 85 to 105 c. 140 error (kpa) error limits for pressure mpx4080d f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
358 motorola sensor device data www.motorola.com/semiconductors pressure (p1)/vacuum (p2) side identification table motorola designates the two sides of the pressure sensor as the pressure (p1) side and the vacuum (p2) side. the pressure (p1) side is the side containing fluoro silicone gel which protects the die from harsh media. the motorola pres- sure sensor is designed to operate with positive differential pressure applied, p1 > p2. the pressure (p1) side is identified by the stainless steel cap. ordering information: the mpx4080d is available only in the unibody package. device order no device type case no device marking device order no . device type case no . device marking mpx4080d differential 867 mpx4080d f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
359 motorola sensor device data www.motorola.com/semiconductors
#!# !""$! "! "$# !""$! "! # !#$! "# !# the motorola mpx4100 series manifold absolute pressure (map) sensor for engine control is designed to sense absolute air pressure within the intake manifold. this measurement can be used to compute the amount of fuel required for each cylinder. the small form factor and high reliability of onchip integration makes the motorola map sensor a logical and economical choice for automotive system designers. features ? 1.8% maximum error over 0 to 85 c ? specifically designed for intake manifold absolute pressure sensing in engine control systems ? ideally suited for microprocessor interfacing ? temperature compensated over 40 c to +125 c ? durable epoxy unibody element ? ideal for nonautomotive applications application examples ? manifold sensing for automotive systems figure 1. fully integrated pressure sensor schematic v s 3 sensing element 1 v out 2 gnd thin film temperature compensation and gain stage #1 gain stage #2 and ground reference shift circuitry pins 4, 5 and 6 are no connects the mpx4100 series piezoresistive transducer is a state oftheart, monolithic, signal conditioned, silicon pressure sensor. this sensor combines advanced micromachining techniques, thin film metallization, and bipolar semiconductor processing to provide an accurate, high level analog output signal that is proportional to applied pressure. figure 1 shows a block diagram of the internal circuitry integrated on a pressure sensor chip. semiconductor technical data
integrated pressure sensor 20 to 105 kpa (2.9 to 15.2 psi) 0.3 to 4.9 v output pin number note: pins 4, 5, and 6 are internal device connections. do not connect to external circuitry or ground. pin 1 is noted by the notch in the lead. basic chip carrier element case 86708, style 1 1 2 3 v out gnd v s 4 5 6 n/c n/c n/c rev 5 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

360 motorola sensor device data www.motorola.com/semiconductors maximum ratings (1) parametric symbol value unit overpressure (2) (p1 > p2) p max 400 kpa burst pressure (2) (p1 > p2) p burst 1000 kpa storage temperature t stg 40 to +125 c operating temperature t a 40 to +125 c 1. t c = 25 c unless otherwise noted. 2. exposure beyond the specified limits may cause permanent damage or degradation to the device. operating characteristics (v s = 5.1 vdc, t a = 25 c unless otherwise noted, p1 > p2) characteristic symbol min typ max unit pressure range (1) p op 20 e 105 kpa supply voltage (1) v s 4.85 5.1 5.35 vdc supply current i o e 7.0 10 madc minimum pressure offset (3) (0 to 85 c) @ v s = 5.1 volts v off 0.225 0.306 0.388 vdc full scale output (4) (0 to 85 c) @ v s = 5.1 volts v fso 4.815 4.897 4.978 vdc full scale span (5) (0 to 85 c) @ v s = 5.1 volts v fss e 4.59 e vdc accuracy (6) (0 to 85 c) e e e 1.8 %v fss sensitivity v/p e 54 e mv/kpa response time (7) t r e 1.0 e ms output source current at full scale output i o+ e 0.1 e madc warmup time (8) e e 20 e ms offset stability (9) e e 0.5 e %v fss decoupling circuit shown in figure 3 required to meet electrical specifications. mechanical characteristics characteristic symbol min typ max unit weight, basic element (case 867) e e 4.0 e grams common mode line pressure (10) e e e 690 kpa notes: 1. 1.0 kpa (kilopascal) equals 0.145 psi. 2. device is ratiometric within this specified excitation range. 3. offset (v off ) is defined as the output voltage at the minimum rated pressure. 4. full scale output (v fso ) is defined as the output voltage at the maximum or full rated pressure. 5. full scale span (v fss ) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 6. accuracy (error budget) consists of the following: ? linearity: output deviation from a straight line relationship with pressure over the specified pressure range. ? temperature hysteresis: output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. ? pressure hysteresis: output deviation at any pressure within the specified range, when this pressure is cycled to and from the minimum or maximum rated pressure, at 25 c. ? tcspan: output deviation over the temperature range of 0 to 85 c, relative to 25 c. ? tcoffset: output deviation with minimum rated pressure applied, over the temperature range of 0 to 85 c, relative to 25 c. ? variation from nominal: the variation from nominal values, for offset or full scale span, as a percent of v fss , at 25 c. 7. response time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when s ubjected to a specified step change in pressure. 8. warmup is defined as the time required for the product to meet the specified output voltage after the pressure has been stab ilized. 9. offset stability is the product's output deviation when subjected to 1000 hours of pulsed pressure, temperature cycling with bias test. 10. common mode pressures beyond specified may result in leakage at the casetolead interface. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

361 motorola sensor device data www.motorola.com/semiconductors figure 2. cross sectional diagram (not to scale) fluoro silicone gel die coat wire bond lead frame stainless steel cap epoxy plastic case die bond absolute element sealed vacuum reference die p1 p2 figure 3. recommended power supply decoupling. for output filtering recommendations, please refer to application note an1646. 1.0 f ips output 3 5 v 0.01 f 2 1 figure 2 illustrates an absolute sensing chip in the basic chip carrier (case 867). a fluorosilicone gel isolates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the sen- sor diaphragm. the mpx4100a series pressure sensor operating characteristics, and internal reliability and quali- fication tests are based on use of dry air as the pressure media. media, other than dry air, may have adverse effects on sensor performance and longterm reliability. contact the factory for information regarding media compatibility in your application. figure 4 shows the sensor output signal relative to pres- sure input. typical, minimum, and maximum output curves are shown for operation over a temperature range of 0 to 85 c. (the output will saturate outside of the specified pres- sure range.) output (volts) 5.0 4.5 4.0 3.5 3.0 pressure (ref: to sealed vacuum) in kpa typ max min 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 2.5 2.0 1.5 1.0 0.5 0 110 figure 4. output versus absolute pressure temp = 0 to 85 c 20 kpa to 105 kpa mpx4100a transfer function: v out = v s * (.01059*p.152) error v s = 5.1 vdc f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

362 motorola sensor device data www.motorola.com/semiconductors transfer function (mpx4100a) nominal transfer value: v out = v s (p x 0.01059 0.1518) +/ (pressure error x temp. factor x 0.01059 x v s ) v s = 5.1 v 0.25 vdc temperature error band mpx4100a series temp multiplier 40 3 0 to 85 1 +125 3 temperature in c 4.0 3.0 2.0 0.0 1.0 40 20 0 20 40 60 140 120 100 80 temperature error factor pressure error band error limits for pressure 3.0 2.0 1.0 1.0 2.0 3.0 0.0 20 40 60 80 100 120 pressure (in kpa) pressure error (kpa) pressure error (max) 20 to 105 (kpa) 1.5 (kpa) f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

363 motorola sensor device data www.motorola.com/semiconductors pressure (p1)/vacuum (p2) side identification table motorola designates the two sides of the pressure sensor as the pressure (p1) side and the vacuum (p2) side. the pressure (p1) side is the side containing fluorosilicone gel which protects the die from harsh media. the motorola mpx pressure sensor is designed to operate with positive differen- tial pressure applied, p1 > p2. the pressure (p1) side may be identified by using the table below: part number case type pressure (p1) side identifier mpx4100a 86708 stainless steel cap mpx4100ap 867b04 side with port marking mpx4100as 867e03 side with port attached mpx4100asx 867f03 side with port attached ordering information the mpx4100a series map silicon pressure sensors are available in the basic element, or with pressure port fittings that provide mounting ease and barbed hose connections. mpx series device type options case type order number device marking basic element absolute, element only 86708 mpx4100a mpx4100a ported elements absolute, ported 867b04 mpx4100ap mpx4100ap absolute, stove pipe port 867e03 mpx4100as mpx4100a absolute, axial port 867f03 mpx4100asx mpx4100a f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
364 motorola sensor device data www.motorola.com/semiconductors
#!# !""$! "! ! "$# !""$! #" # !#$! "# !# the motorola mpx4100a/mpxa4100a series manifold absolute pressure (map) sensor for engine control is designed to sense absolute air pressure within the intake manifold. this measurement can be used to compute the amount of fuel required for each cylinder. the small form factor and high reliability of onchip integration makes the motorola map sensor a logical and economical choice for automotive system designers. the mpx4100a/mpxa4100a series piezoresistive transducer is a stateoftheart, monolithic, signal conditioned, silicon pressure sensor. this sensor combines advanced micromachining techniques, thin film metallization, and bipolar semiconductor processing to provide an accurate, high level analog output signal that is proportional to applied pressure. figure 1 shows a block diagram of the internal circuitry integrated on a pressure sensor chip. features ? 1.8% maximum error over 0 to 85 c ? specifically designed for intake manifold absolute pressure sensing in engine control systems ? temperature compensated over 40 c to +125 c ? durable epoxy unibody element or thermoplastic (pps) surface mount package application examples ? manifold sensing for automotive systems ? ideally suited for microprocessor or microcontroller based systems ? also ideal for nonautomotive applications v s sensing element v out gnd thin film temperature compensation and gain stage #1 gain stage #2 and ground reference shift circuitry pins 1, 5, 6, 7 and 8 are no connects for small outline package device pins 4, 5 and 6 are no connects for unibody device figure 1. fully integrated pressure sensor schematic semiconductor technical data integrated pressure sensor 15 to 115 kpa (2.2 to 16.7 psi) 0.2 to 4.8 volts output pin number note: pins 4, 5, and 6 are internal device connections. do not connect to external circuitry or ground. pin 1 is noted by the notch in the lead. mpx4100a case 867 mpx4100ap case 867b 1 2 3 v out gnd v s 4 5 6 n/c n/c n/c unibody package pin number note: pins 1, 5, 6, 7, and 8 are internal device connections. do not connect to external circuitry or ground. pin 1 is noted by the notch in the lead. 1 2 3 n/c v s gnd 5 6 7 n/c n/c n/c mpxa4100a6u case 482 mpxa4100ac6u case 482a 4v out 8 n/c small outline package mpx4100as case 867e
rev 5 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

365 motorola sensor device data www.motorola.com/semiconductors maximum ratings (note) parametrics symbol value units maximum pressure (p1 p2) p max 400 kpa storage temperature t stg 40 to +125 c operating temperature t a 40 to +125 c note: exposure beyond the specified limits may cause permanent damage or degradation to the device. operating characteristics (v s = 5.1 vdc, t a = 25 c unless otherwise noted, p1 > p2. decoupling circuit shown in figure 3 required to meet electrical specifications.) characteristic symbol min typ max unit pressure range (1) p op 20 e 105 kpa supply voltage (2) v s 4.85 5.1 5.35 vdc supply current i o e 7.0 10 madc minimum pressure offset (3) (0 to 85 c) @ v s = 5.1 volts v off 0.225 0.306 0.388 vdc full scale output (4) (0 to 85 c) @ v s = 5.1 volts v fso 4.870 4.951 5.032 vdc full scale span (5) (0 to 85 c) @ v s = 5.1 volts v fss e 4.59 e vdc accuracy (6) (0 to 85 c) e e e 1.8 %v fss sensitivity v/p e 54 e mv/kpa response time (7) t r e 1.0 e ms output source current at full scale output i o+ e 0.1 e madc warmup time (8) e e 20 e ms offset stability (9) e e 0.5 e %v fss notes: 1. 1.0 kpa (kilopascal) equals 0.145 psi. 2. device is ratiometric within this specified excitation range. 3. offset (v off ) is defined as the output voltage at the minimum rated pressure. 4. full scale output (v fso ) is defined as the output voltage at the maximum or full rated pressure. 5. full scale span (v fss ) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 6. accuracy (error budget) consists of the following: ? linearity: output deviation from a straight line relationship with pressure over the specified pressure range. ? temperature hysteresis: output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. ? pressure hysteresis: output deviation at any pressure within the specified range, when this pressure is cycled to and from the minimum or maximum rated pressure, at 25 c. ? tcspan: output deviation over the temperature range of 0 to 85 c, relative to 25 c. ? tcoffset: output deviation with minimum rated pressure applied, over the temperature range of 0 to 85 c, relative to 25 c. ? variation from nominal: the variation from nominal values, for offset or full scale span, as a percent of v fss , at 25 c. 7. response time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when s ubjected to a specified step change in pressure. 8. warmup time is defined as the time required for the product to meet the specified output voltage after the pressure has been stabilized. 9. offset stability is the product's output deviation when subjected to 1000 hours of pulsed pressure, temperature cycling with bias test. mechanical characteristics characteristics typ unit weight, basic element (case 867) 4.0 grams weight, small outline package (case 482) 1.5 grams f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

366 motorola sensor device data www.motorola.com/semiconductors figure 2. cross sectional diagram sop (not to scale) figure 3. recommended power supply decoupling and output filtering. for additional output filtering, please refer to application note an1646. 1.0 f ips 470 pf output vs 5 v 0.01 f gnd vout wire bond stainless steel cap thermoplastic case die bond sealed vacuum reference die p1 fluoro silicone gel die coat lead frame absolute element figure 2 illustrates the absolute sensing chip in the basic chip carrier (case 482). figure 3 shows the recommended decoupling circuit for interfacing the output of the integrated sensor to the a/d in- put of a microprocessor or microcontroller. proper decoup- ling of the power supply is recommended. output (volts) 5.0 4.5 4.0 3.5 3.0 pressure (ref: to sealed vacuum) in kpa typ max min 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 2.5 2.0 1.5 1.0 0.5 0 110 temp = 0 to 85 c 20 kpa to 105 kpa mpx4100a transfer function: v out = v s * (.01059*p.152) error v s = 5.1 vdc figure 4. output versus absolute pressure figure 4 shows the sensor output signal relative to pres- sure input. typical, minimum, and maximum output curves are shown for operation over a temperature range of 0 to 85 c. the output will saturate outside of the specified pres- sure range. a fluorosilicone gel isolates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the sensor diaphragm. the mpx4100a/mpxa4100a series pressure sensor operat- ing characteristics, and internal reliability and qualification tests are based on use of dry air as the pressure media. media, other than dry air, may have adverse effects on sensor performance and longterm reliability. contact the factory for information regarding media compatibility in your application. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

367 motorola sensor device data www.motorola.com/semiconductors transfer function (mpx4100a, mpxa4100a) nominal transfer value: v out = v s (p x 0.01059 0.1518) +/ (pressure error x temp. factor x 0.01059 x v s ) v s = 5.1 v 0.25 vdc temperature error band mpx4100a, mpxa4100a series temp multiplier 40 3 0 to 85 1 +125 3 temperature in c 4.0 3.0 2.0 0.0 1.0 40 20 0 20 40 60 140 120 100 80 temperature error factor note: the temperature multiplier is a linear response from 0 c to 40 c and from 85 c to 125 c. pressure error band error limits for pressure 3.0 2.0 1.0 1.0 2.0 3.0 0.0 20 40 60 80 100 120 pressure (in kpa) pressure error (kpa) pressure error (max) 20 to 105 (kpa) 1.5 (kpa) f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

368 motorola sensor device data www.motorola.com/semiconductors pressure (p1)/vacuum (p2) side identification table motorola designates the two sides of the pressure sensor as the pressure (p1) side and the vacuum (p2) side. the pressure (p1) side is the side containing fluorosilicone gel which protects the die from harsh media. the motorola mpx pressure sensor is designed to operate with positive differen- tial pressure applied, p1 > p2. the pressure (p1) side may be identified by using the table below: part number case type pressure (p1) side identifier mpx4100a 867 stainless steel cap mpx4100ap 867b side with port marking mpx4100as 867e side with port attached mpxa4100a6u/t1 482 stainless steel cap mpxa4100ac6u 482a side with port attached ordering information e unibody package mpx series device type options case type order number device marking basic element absolute, element only 867 mpx4100a mpx4100a ported elements absolute, ported 867b mpx4100ap mpx4100ap absolute, stove pipe port 867e mpx4100as mpx4100a ordering information e small outline package device type options case no. mpx series order no. packing options marking basic element absolute, element only 482 mpxa4100a6u rails mpxa4100a absolute, element only 482 mpxa4100a6t1 tape and reel mpxa4100a ported element absolute, axial port 482a mpxa4100ac6u rails mpxa4100a f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

369 motorola sensor device data www.motorola.com/semiconductors information for using the small outline package (case 482) minimum recommended footprint for surface mounted applications surface mount board layout is a critical portion of the total design. the footprint for the surface mount packages must be the correct size to ensure proper solder connection inter- face between the board and the package. with the correct footprint, the packages will self align when subjected to a solder reflow process. it is always recommended to design boards with a solder mask layer to avoid bridging and short- ing between solder pads. 0.660 16.76 0.060 typ 8x 1.52 0.100 typ 8x 2.54 0.100 typ 8x 2.54 0.300 7.62 inch mm scale 2:1 figure 5. sop footprint (case 482) f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
370 motorola sensor device data www.motorola.com/semiconductors %#% ! #$$&# $!# !# ! $!&% #$$&# ""%! $ " ! %! "#%&# !" $% #% the motorola mpx4101a/mpxa4101a/mpxh6101a series manifold absolute pressure (map) sensor for engine control is designed to sense absolute air pressure within the intake manifold. this measurement can be used to compute the amount of fuel required for each cylinder. the small form factor and high reliability of onchip integration makes the motorola map sensor a logical and economical choice for automotive system designers. the mpx4101a/mpxa4101a/mpxh 6101a series piezoresistive transducer is a stateoftheart, monolithic, signal conditioned, silicon pressure sensor. this sensor combines advanced micromachining tec hniques, thin film metallization, and bipolar semiconductor processing to provide an accurate, high level analog output signal that is proportional to applied pressure. figure 1 shows a block diagram of the internal circuitry integrated on a pressure sensor chip. features ? 1.72% maximum error over 0 to 85 c ? specifically designed for intake manifold absolute pressure sensing in engine control systems ? temperature compensated over 40 c to +125 c ? durable epoxy unibody element or thermoplastic (pps) surface mount package application examples ? manifold sensing for automotive systems ? ideally suited for microprocessor or microcontrollerbased systems ? also ideal for nonautomotive applications figure 1. fully integrated pressure sensor schematic v s sensing element v out gnd thin film temperature compensation and gain stage #1 gain stage #2 and ground reference shift circuitry pins 4, 5 and 6 are no connects for unibody device pins 1, 5, 6, 7 and 8 are no connects for small outline device semiconductor technical data

integrated pressure sensor 15 to 102 kpa (2.18 to 14.8 psi) 0.25 to 4.95 v output mpx4101a case 867 unibody package pin number note: pins 4, 5, and 6 are internal device connections. do not connect to external circuitry or ground. pin 1 is noted by the notch in the lead. 1 2 3 v out gnd v s 4 5 6 n/c n/c n/c small outline package mpxa4101ac6u case 482a pin number 1 2 3 n/c v s gnd 5 6 7 n/c n/c n/c 4v out 8 n/c note: pins 1, 5, 6, 7, and 8 are not device connections. do not connect to external circuitry or ground. pin 1 is noted by the notch in the lead. mpxh6101a6t1 case 1317 pin number note: pins 1, 5, 6, 7, and 8 are internal device connections. do not connect to external circuitry or ground. pin 1 is denoted by the chamfered corner of the package. 1 2 3 n/c v s gnd 5 6 7 n/c n/c n/c 4v out 8 n/c super small outline package rev 4 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

371 motorola sensor device data www.motorola.com/semiconductors maximum ratings (note) parametric symbol value unit maximum pressure (p1 > p2) p max 400 kpa storage temperature t stg 40 to +125 c operating temperature t a 40 to +125 c note: exposure beyond the specified limits may cause permanent damage or degradation to the device. operating characteristics (v s = 5.1 vdc, t a = 25 c unless otherwise noted, p1 > p2. decoupling circuit shown in figure 3 required to meet electrical specifications.) characteristic symbol min typ max unit pressure range (1) p op 15 e 102 kpa supply voltage (2) v s 4.85 5.1 5.35 vdc supply current i o e 7.0 10 madc minimum pressure offset (3) (0 to 85 c) @ v s = 5.1 volts v off 0.171 0.252 0.333 vdc full scale output (4) (0 to 85 c) @ v s = 5.1 volts v fso 4.870 4.951 5.032 vdc full scale span (5) (0 to 85 c) @ v s = 5.1 volts v fss e 4.7 e vdc accuracy (6) (0 to 85 c) e e e 1.72 %v fss sensitivity v/p e 54 e mv/kpa response time (7) t r e 15 e ms output source current at full scale output i o+ e 0.1 e madc warmup time (8) e e 20 e ms offset stability (9) e e 0.5 e %v fss notes: 1. 1.0 kpa (kilopascal) equals 0.145 psi. 2. device is ratiometric within this specified excitation range. 3. offset (v off ) is defined as the output voltage at the minimum rated pressure. 4. full scale output (v fso ) is defined as the output voltage at the maximum or full rated pressure. 5. full scale span (v fss ) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 6. accuracy (error budget) consists of the following: ? linearity: output deviation from a straight line relationship with pressure over the specified pressure range. ? temperature hysteresis: output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. ? pressure hysteresis: output deviation at any pressure within the specified range, when this pressure is cycled to and from the minimum or maximum rated pressure, at 25 c. ? tcspan: output deviation over the temperature range of 0 to 85 c, relative to 25 c. ? tcoffset: output deviation with minimum rated pressure applied, over the temperature range of 0 to 85 c, relative to 25 c. ? variation from nominal: the variation from nominal values, for offset or full scale span, as a percent of v fss , at 25 c. 7. response time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when s ubjected to a specified step change in pressure. 8. warmup time is defined as the time required for the product to meet the specified output voltage after the pressure has been stabilized. 9. offset stability is the product's output deviation when subjected to 1000 hours of pulsed pressure, temperature cycling with bias test. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

372 motorola sensor device data www.motorola.com/semiconductors figure 2. cross sectional diagram ssop (not to scale) wire bond stainless steel cap thermoplastic case die bond sealed vacuum reference die p1 fluoro silicone gel die coat lead frame absolute element figure 2 illustrates an absolute sensing chip in the super small outline package (case 1317). output (volts) 5 . 0 4.5 4.0 3.5 3.0 pressure (ref: to sealed vacuum) in kpa typ max min 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 2.5 2.0 1.5 1.0 0.5 0 110 transfer function: v out = v s * (px0.01059*p0.10941) error figure 3. recommended power supply decoupling and output filtering. figure 4. output versus absolute pressure v s = 5.1 vdc temp = 0 to 85 c 20 kpa to 105 kpa mpx4101a v s pin 2 5.1 v gnd pin 3 v out pin 4 to adc 100 nf 51 k 47 pf mpxh6101a figure 4 shows the sensor output signal relative to pres- sure input. typical, minimum, and maximum output curves are shown for operation over a temperature range of 0 to 85 c. the output will saturate outside of the specified pres- sure range. a fluorosilicone gel isolates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the sensor diaphragm. the mpx4101a/mpxa4101a/mpxh 6101a series pressure sen- sor operating characteristics, and internal reliability and qual- ification tests are based on use of dry air as the pressure media. media, other than dry air, may have adverse effects on sensor performance and longterm reliability. contact the factory for information regarding media compatibility in your application. figure 3 shows the recommended decoupling circuit for interfacing the output of the integrated sensor to the a/d in- put of a microprocessor or microcontroller. proper decoup- ling of the power supply is recommended. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

373 motorola sensor device data www.motorola.com/semiconductors nominal transfer value: v out = v s (p x 0.01059 0.10941) +/ (pressure error x temp. factor x 0.01059 x v s ) v s = 5.1 v 0.25 vdc transfer function (mpx4101a, mpxa4101a, mpxh 6101a) temperature error band temperature in c 4.0 3.0 2.0 0.0 1.0 40 20 0 20 40 60 120 100 80 mpx4101a, mpxa4101a, mpxh6101a series temp multiplier 40 3 0 to 85 1 +125 3 temperature error factor 140 note: the temperature multiplier is a linear response from 0 to 40 c and from 85 to 125 c. pressure error band error limits for pressure pressure (in kpa) 3.0 2.0 1.0 1.0 2.0 3.0 0.0 01530456075 90 105 120 pressure error (kpa) pressure error (max) 15 to 102 (kpa) 1.5 (kpa) f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

374 motorola sensor device data www.motorola.com/semiconductors pressure (p1)/vacuum (p2) side identification table motorola designates the two sides of the pressure sensor as the pressure (p1) side and the vacuum (p2) side. the pressure (p1) side is the side containing fluorosilicone gel which protects the die from harsh media. the motorola pres- sure sensor is designed to operate with positive differential pressure applied, p1 > p2. the pressure (p1) side may be identified by using the table below: part number case type pressure (p1) side identifier mpx4101a 867 stainless steel cap mpxa4101ac6u 482a side with port attached mpxh6101a6u 1317 stainless steel cap mpxh6101a6t1 1317 stainless steel cap ordering information e unibody package the mpx4101a series map silicon pressure sensors are available in the basic element, or with pressure port fittings that provide mounting ease and barbed hose connections. mpx series device type options case type order number device marking basic element absolute, element only 867 mpx4101a mpx4101a ordering information e small outline package device type options case no. mpx series order no. packing options marking ported element absolute, axial port 482a mpxa4101ac6u rails mpxa4101a ordering information e super small outline package device type options case no. mpx series order no. packing options marking basic element absolute, element only 1317 mpxh6101a6u rails mpxh6101a basic element absolute, element only 1317 mpxh6101a6t1 tape and reel mpxh6101a information for using the small outline packages minimum recommended footprint for surface mounted applications surface mount board layout is a critical portion of the total design. the footprint for the surface mount packages must be the correct size to ensure proper solder connection inter- face between the board and the package. with the correct footprint, the packages will self align when subjected to a solder reflow process. it is always recommended to design boards with a solder mask layer to avoid bridging and short- ing between solder pads. 0.660 16.76 0.060 typ 8x 1.52 0.100 typ 8x 2.54 0 . 100 ty p 8x 2.54 0.300 7.62 figure 5. sop footprint (case 482) inch mm scale 2:1 figure 6. ssop footprint (case 1317) 0.027 typ 8x 0.69 0.053 typ 8x 1.35 inch mm 0 .3 87 9.83 0.150 3.81 0 . 050 1.27 typ f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
375 motorola sensor device data www.motorola.com/semiconductors $"$ "##%" # " " # %$ "##%" !!$ # ! $ !"$%" !#$ "$ the motorola mpx4105a series manifold absolute pressure (map) sensor for engine control is designed to sense absolute air pressure within the intake manifold. this measurement can be used to compute the amount of fuel required for each cylinder. motorola's map sensor integrates onchip, bipolar op amp circuitry and thin film resistor networks to provide a high output signal and temperature compensation. the small form factor and high reliability of onchip integration make the motorola map sensor a logical and economical choice for the automotive system designer. the mpx4105a series piezoresistive transducer is a stateoftheart, monolithic, signal conditioned, silicon pressure sensor. this sensor combines advanced micromachining techniques, thin film metallization, and bipolar semiconductor processing to provide an accurate, high level analog output signal that is proportional to applied pressure. figure 1 shows a block diagram of the internal circuitry integrated on a pressure sensor chip. features ? 1.8% maximum error over 0 to 85 c ? specifically designed for intake manifold absolute pressure sensing in engine control systems ? temperature compensated over 40 to +125 c ? durable epoxy unibody element application examples ? manifold sensing for automotive systems ? ideally suited for microprocessor or microcontrollerbased systems ? also ideal for nonautomotive applications figure 1. fully integrated pressure sensor schematic v s sensing element v out gnd thin film temperature compensation and gain stage #1 gain stage #2 and ground reference shift circuitry pins 4, 5 and 6 are no connects for unibody device semiconductor technical data

mpx4105a case 867 unibody package pin number note: pins 4, 5, and 6 are internal device connections. do not connect to external circuitry or ground. pin 1 is noted by the notch in the lead. 1 2 3 v out gnd v s 4 5 6 n/c n/c n/c integrated pressure sensor 15 to 105 kpa (2.2 to 15.2 psi) 0.3 to 4.9 v output rev 4 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

376 motorola sensor device data www.motorola.com/semiconductors maximum ratings (note) parametrics symbol value units maximum pressure (p1 p2) p max 400 kpa storage temperature t stg 40 to +125 c operating temperature t a 40 to +125 c note: exposure beyond the specified limits may cause permanent damage or degradation to the device. operating characteristics (v s = 5.1 vdc, t a = 25 c unless otherwise noted. decoupling circuit shown in figure 3 required to meet specification.) characteristic symbol min typ max unit pressure range p op 15 e 105 kpa supply voltage (1) v s 4.85 5.1 5.35 vdc supply current i o e 7.0 10 madc minimum pressure offset (2) (0 to 85 c) v off 0.184 0.306 0.428 vdc full scale output (3) (0 to 85 c) v fso 4.804 4.896 4.988 vdc full scale span (4) (0 to 85 c) v fss e 4.590 e vdc accuracy (5) (0 to 85 c) e e e 1.8 %v fss sensitivity d v/ d p e 51 e mv/kpa response time (6) t r e 1.0 e ms output source current at full scale output i o+ e 0.1 e madc warmup time (7) e e 15 e ms offset stability (8) e e 0.65 e %v fss notes: 1. device is ratiometric within this specified excitation range. 2. offset (v off ) is defined as the output voltage at the minimum rated pressure. 3. full scale output (v fso ) is defined as the output voltage at the maximum or full rated pressure. 4. full scale span (v fss ) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 5. accuracy is the deviation in actual output from nominal output over the entire pressure range and temperature range as a perc ent of span at 25 c due to all sources of error including the following: ? linearity: output deviation from a straight line relationship with pressure over the specified pressure range. ? temperature hysteresis: output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with minimum specified pressure applied. ? pressure hysteresis: output deviation at any pressure within the specified range, when this pressure is cycled to and from minimum or maximum rated pressure at 25 c. ? tcspan: span deviation per c over the temperature range of 0 to 85 c, as a percent of span at 25 c. ? tcoffset: output deviation per c with minimum pressure applied, over the temperature range of 0 to 85 c. 6. response time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when s ubjected to a specified step change in pressure. 7. warmup time is defined as the time required for the product to meet the specified output voltage. 8. offset stability is the product's output deviation when subjected to 1000 hours of pulsed pressure, temperature cycling with bias test. mechanical characteristics characteristics typ unit weight, basic element (case 867) 4.0 grams f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

377 motorola sensor device data www.motorola.com/semiconductors figure 2. crosssectional diagram (not to scale) fluoro silicone gel die coat wire bond lead frame stainless steel cap epoxy plastic case die bond absolute element sealed vacuum reference die p1 p2 figure 3. recommended power supply decoupling and output filtering. for additional output filtering, please refer to application note an1646. 1.0 f ips 470 pf output vs 5 v 0.01 f gnd vout figure 2 illustrates an absolute sensing chip in the basic chip carrier (case 867). a fluorosilicone gel isolates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the sensor d iaphragm. the mpx4105a series pressure sensor operating characteristics, internal reliability and qualification tests are based on use of dry air as the pressure media. media other than dry air may have adverse effects on sensor performance and longterm reliability. contact the factory for information regarding me- dia compatibility in your application. figure 3 shows the recommended decoupling circuit for in- terfacing the output of the integrated sensor to the a/d input of a microprocessor or microcontroller. proper decoupling of the power supply is recommended. output (volts) 5.0 4.5 4.0 3.5 3.0 pressure (ref: to sealed vacuum) in kpa max min 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 2.5 2.0 1.5 1.0 0.5 0 105 figure 4. output versus absolute pressure temp = 0 to 85 c 15 kpa to 105 kpa mpx4105a transfer function: v out = v s * (0.01*p0.09) error v s = 5.1 vdc 110 typ figure 4 shows the sensor output signal relative to pres- sure input. typical minimum and maximum output curves are shown for operation over a temperature range of 0 to 85 c. the output will saturate outside of the specified pressure range. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

378 motorola sensor device data www.motorola.com/semiconductors transfer function (mpx4105a) nominal transfer value: v out = v s (p x 0.01 0.09) +/ (pressure error x temp. factor x 0.01 x v s ) v s = 5.1 v 0.25 vdc temperature error band mpx4105a series break points temp multiplier 40 3.0 20 1.5 0 to 85 1.0 125 2.5 temperature in c 4.0 3.0 2.0 0.0 1.0 40 20 0 20 40 60 140 120 100 80 temperature error factor note: the temperature multiplier is a linear response from 40 c to 20 c, 20 c to 0 c, and from 85 c to 125 c pressure error band error limits for pressure 3.0 2.0 1.0 1.0 2.0 3.0 0.0 20 40 60 80 100 120 pressure (in kpa) pressure error (kpa) pressure error (max) 40 to 94 (kpa) 1.5 (kpa) 15 (kpa) 2.4 (kpa) 105 (kpa) 1.8 (kpa) ordering information e unibody package device type options case no mpx series order no marking device type options case no . mpx series order no . marking basic element absolute element 867 mpx4105a mpx4105a basic element absolute , element 867 mpx4105a mpx4105a f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
379 motorola sensor device data www.motorola.com/semiconductors $"$ "##%" # " " # %$ "##%" $$" " " $" !!$ # ! $ !"$%" !#$ "$ motorola's mpx4115a/mpxa4115a series sensor integrates onc hip, bipolar op amp circuitry and thin film resistor networks to provide a high output signal and temperature compensation. the small form factor and high reliability of onchip integration make the motorola pressure sensor a logical and economical choice for the system designer. the mpx4115a/mpxa4115a series piezoresistive transducer is a stateoftheart, monolithic, signal conditioned, silicon pressure sensor. this sensor combines advanced micromachining tec hniques, thin film metallization, and bipolar semiconductor processing to provide an accurate, high level analog output signal that is proportional to applied pressure. figure 1 shows a block diagram of the internal circuitry integrated on a pressure sensor chip. features ? 1.5% maximum error over 0 to 85 c ? ideally suited for microprocessor or microcontroller based systems ? temperature compensated from 40 to +125 c ? durable epoxy unibody element or thermoplastic (pps) surface mount package application examples ? aviation altimeters ? industrial controls ? engine control ? weather stations and weather reporting devices figure 1. fully integrated pressure sensor schematic v s sensing element v out gnd thin film temperature compensation and gain stage #1 gain stage #2 and ground reference shift circuitry pins 1, 5, 6, 7 and 8 are no connects for small outline package device pins 4, 5 and 6 are no connects for unibody device semiconductor technical data

integrated pressure sensor 15 to 115 kpa (2.2 to 16.7 psi) 0.2 to 4.8 volts output pin number note: pins 4, 5, and 6 are internal device connections. do not connect to external circuitry or ground. pin 1 is noted by the notch in the lead. mpx4115a case 867 mpx4115ap case 867b 1 2 3 v out gnd v s 4 5 6 n/c n/c n/c unibody package pin number note: pins 1, 5, 6, 7, and 8 are internal device connections. do not connect to external circuitry or ground. pin 1 is noted by the notch in the lead. 1 2 3 n/c v s gnd 5 6 7 n/c n/c n/c mpxa4115a6u case 482 mpxa4115ac6u case 482a 4v out 8 n/c small outline package mpx4115as case 867e rev 4 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

380 motorola sensor device data www.motorola.com/semiconductors maximum ratings (note) parametrics symbol value units maximum pressure (p1 p2) p max 400 kpa storage temperature t stg 40 to +125 c operating temperature t a 40 to +125 c note: exposure beyond the specified limits may cause permanent damage or degradation to the device. operating characteristics (v s = 5.1 vdc, t a = 25 c unless otherwise noted, p1 p2. decoupling circuit shown in figure 3 required to meet electrical specifications.) characteristic symbol min typ max unit pressure range p op 15 e 115 kpa supply voltage (1) v s 4.85 5.1 5.35 vdc supply current i o e 7.0 10 madc minimum pressure offset (2) (0 to 85 c) @ v s = 5.1 volts v off 0.135 0.204 0.273 vdc full scale output (3) (0 to 85 c) @ v s = 5.1 volts v fso 4.725 4.794 4.863 vdc full scale span (4) (0 to 85 c) @ v s = 5.1 volts v fss 4.521 4.590 4.659 vdc accuracy (5) (0 to 85 c) e e e 1.5 %v fss sensitivity v/p e 45.9 e mv/kpa response time (6) t r e 1.0 e ms output source current at full scale output i o+ e 0.1 e madc warmup time (7) e e 20 e ms offset stability (8) e e 0.5 e %v fss notes: 1. device is ratiometric within this specified excitation range. 2. offset (v off ) is defined as the output voltage at the minimum rated pressure. 3. full scale output (v fso ) is defined as the output voltage at the maximum or full rated pressure. 4. full scale span (v fss ) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 5. accuracy is the deviation in actual output from nominal output over the entire pressure range and temperature range as a perc ent of span at 25 c due to all sources of error including the following: ? linearity: output deviation from a straight line relationship with pressure over the specified pressure range. ? temperature hysteresis: output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. ? pressure hysteresis: output deviation at any pressure within the specified range, when this pressure is cycled to and from minimum or maximum rated pressure at 25 c. ? tcspan: output deviation over the temperature range of 0 to 85 c, relative to 25 c. ? tcoffset: output deviation with minimum pressure applied, over the temperature range of 0 to 85 c, relative to 25 c. 6. response time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when s ubjected to a specified step change in pressure. 7. warmup time is defined as the time required for the product to meet the specified output voltage after the pressure has been stabilized. 8. offset stability is the product's output deviation when subjected to 1000 cycles of pulsed pressure, temperature cycling with bias test. mechanical characteristics characteristics typ unit weight, basic element (case 867) 4.0 grams weight, small outline package (case 482) 1.5 grams f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

381 motorola sensor device data www.motorola.com/semiconductors figure 2. cross sectional diagram sop (not to scale) figure 3. recommended power supply decoupling and output filtering. for additional output filtering, please refer to application note an1646. 1.0 f ips 470 pf output vs 5 v 0.01 f gnd vout wire bond stainless steel cap thermoplastic case die bond sealed vacuum reference die p1 fluoro silicone gel die coat lead frame absolute element figure 2 illustrates the absolute sensing chip in the basic chip carrier (case 482). figure 3 shows the recommended decoupling circuit for interfacing the output of the integrated sensor to the a/d in- put of a microprocessor or microcontroller. proper decoup- ling of the power supply is recommended. output (volts) 5.0 4.5 4.0 3.5 3.0 pressure (ref: to sealed vacuum) in kpa typ max min 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 2.5 2.0 1.5 1.0 0.5 0 110 figure 4. output versus absolute pressure transfer function: v out = v s * (.009*p.095) error v s = 5.1 vdc temp = 0 to 85 c 115 120 figure 4 shows the sensor output signal relative to pres- sure input. typical minimum and maximum output curves are shown for operation over 0 to 85 c temperature range. the output will saturate outside of the rated pressure range. a fluorosilicone gel isolates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the s ilicon diaphragm. the mpx4115a/mpxa4115a series pressure sensor operating characteristics, internal reliability and qualification tests are based on use of dry air as the pressure media. media other than dry air may have adverse effects on sensor perfor- mance and longterm reliability. contact the factory for information regarding media compatibility in your application. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

382 motorola sensor device data www.motorola.com/semiconductors transfer function (mpx4115a, mpxa4115a) nominal transfer value: v out = v s x (0.009 x p 0.095) (pressure error x temp. factor x 0.009 x v s ) v s = 5.1 0.25 vdc temperature error band mpx4115a, mpxa4115a series break points temp multiplier 40 3 0 to 85 1 125 3 temperature in c 4.0 3.0 2.0 0.0 1.0 40 20 0 20 40 60 140 120 100 80 temperature error factor note: the temperature multiplier is a linear response from 0 c to 40 c and from 85 c to 125 c pressure error band error limits for pressure 3.0 2.0 1.0 1.0 2.0 3.0 0.0 20 pressure (in kpa) pressure error (kpa) pressure error (max) 15 to 115 (kpa) 1.5 (kpa) 40 60 80 100 120 ordering information e unibody package device type options case no. mpx series order no. marking basic element absolute, element only 867 mpx4115a mpx4115a ported elements absolute, ported 867b mpx4115ap mpx4115ap absolute, stove pipe port 867e mpx4115as mpx4115a ordering information e small outline package device type options case no. mpx series order no. packing options marking basic element absolute, element only 482 mpxa4115a6u rails mpxa4115a absolute, element only 482 mpxa4115a6t1 tape and reel mpxa4115a ported element absolute, axial port 482a mpxa4115ac6u rails mpxa4115a absolute, axial port 482a mpxa4115ac6t1 tape and reel mpxa4115a f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

383 motorola sensor device data www.motorola.com/semiconductors information for using the small outline package (case 482) minimum recommended footprint for surface mounted applications surface mount board layout is a critical portion of the total design. the footprint for the surface mount packages must be the correct size to ensure proper solder connection inter- face between the board and the package. with the correct fottprint, the packages will selfalign when subjected to a solder reflow process. it is always recommended to design boards with a solder mask layer to avoid bridging and short- ing between solder pads. 0.660 16.76 0.060 typ 8x 1.52 0.100 typ 8x 2.54 0.100 typ 8x 2.54 0.300 7.62 figure 5. sop footprint (case 482) inch mm scale 2:1 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
384 motorola sensor device data www.motorola.com/semiconductors
#!# !""$! "! ! "$# !""$! #" # !#$! "# !# the motorola mpx4200a series manifold absolute pressure (map) sensor for turbo boost engine control is designed to sense absolute air pressure within the intake manifold. this measurement can be used to compute the amount of fuel required for each cylinder. the mpx4200a series sensor integrates onchip, bipolar op amp circuitry and thin film resistor networks to provide a high level analog output signal and temperature compensation. the small form factor and reliability of onchip integration make the motorola map sensor a logical and economical choice for automotive system designers. features ? specifically designed for intake manifold absolute pressure sensing in engine control systems ? patented silicon shear stress strain gauge ? temperature compensated over 40 to +125 c ? offers reduction in weight and volume compared to existing hybrid modules ? durable epoxy unibody element application examples ? manifold sensing for automotive systems ? ideally suited for microprocessor or microcontrollerbased systems ? also ideal for nonautomotive applications pins 4, 5 and 6 are no connects figure 1. fully integrated pressure sensor schematic v s sensing element v out gnd thin film temperature compensation and gain stage #1 gain stage #2 and ground reference shift circuitry semiconductor technical data
integrated pressure sensor 20 to 200 kpa (2.9 to 29 psi) 0.3 to 4.9 v output pin number note: pins 4, 5, and 6 are internal device connections. do not connect to external circuitry or ground. pin 1 is noted by the notch in the lead. mpx4200a case 867 1 2 3 v out gnd v s 4 5 6 n/c n/c n/c rev 1 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

385 motorola sensor device data www.motorola.com/semiconductors maximum ratings (note) parametrics symbol value unit maximum pressure (p1 > p2) p max 800 kpa storage temperature t stg 40 to +125 c operating temperature t a 40 to +125 c note: exposure beyond the specified limits may cause permanent damage or degradation to the device. operating characteristics (v s = 5.1 vdc, t a = 25 c unless otherwise noted, p1 > p2. decoupling circuit shown in figure 3 required to meet electrical specifications.) characteristic symbol min typ max unit pressure range (1) p op 20 e 200 kpa supply voltage (2) v s 4.85 5.1 5.35 vdc supply current i o e 7.0 10 madc minimum pressure offset (3) (0 to 85 c) @ v s = 5.1 volts v off 0.199 0.306 0.413 vdc full scale output (4) (0 to 85 c) @ v s = 5.1 volts v fso 4.725 4.896 4.978 vdc full scale span (5) (0 to 85 c) @ v s = 5.1 volts v fss e 4.590 e vdc accuracy (6) (0 to 85 c) e e e 1.5 %v fss sensitivity v/p e 25.5 e mv/kpa response time (7) t r e 1.0 e ms output source current at full scale output l o + e 0.1 e madc warmup time (8) e e 20 e ms offset stability (9) e e 0.5 e %v fss notes: 1. 1.0 kpa (kilopascal) equals 0.145 psi. 2. device is ratiometric within this specified excitation range. 3. offset (v off ) is defined as the output voltage at the minimum rated pressure. 4. full scale output (v fso ) is defined as the output voltage at the maximum or full rated pressure. 5. full scale span (v fss ) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 6. accuracy (error budget) consists of the following: ? linearity: output deviation from a straight line relationship with pressure over the specified pressure range. ? temperature hysteresis: output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. ? pressure hysteresis: output deviation at any pressure within the specified range, when this pressure is cycled to and from the minimum or maximum rated pressure, at 25 c. ? tcspan: output deviation over the temperature range of 0 to 85 c, relative to 25 c. ? tcoffset: output deviation with minimum rated pressure applied, over the temperature range of 0 to 85 c, relative to 25 c. ? variation from nominal: the variation from nominal values, for offset or full scale span, as a percent of v fss at 25 c. 7. response time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when s ubjected to a specified step change in pressure. 8. warmup time is defined as the time required for the product to meet the specified output voltage after the pressure has been stabilized. 9. offset stability is the product's output deviation when subjected to 1000 hours of pulsed pressure, temperature cycling with bias test. mechanical characteristics characteristics typ unit weight, basic element (case 867) 4.0 grams f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

386 motorola sensor device data www.motorola.com/semiconductors figure 2. crosssectional diagram (not to scale) silicone die coat wire bond stainless steel metal cover rtv die bond die p1 p2 epoxy case lead frame sealed vacuum reference 1.0 f ips 470 pf output vs 5 v 0.01 f gnd vout figure 3. recommended power supply decoupling and output filtering. for additional output filtering, please refer to application note an1646. figure 2 illustrates the absolute sensing chip in the basic chip carrier (case 867). a fluorosilicone gel isolates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the sen- sor diaphragm. the mpx4200a series pressure sensor operating characteristics, and internal reliability and quali- fication tests are based on use of dry air as the pressure media. media, other than dry air, may have adverse ef- fects on sensor performance and longterm reliability. contact the factory for information regarding media com- patibility in your application. figure 3 shows the recommended decoupling circuit for interfacing the output of the integrated sensor to the a/d in- put of a microprocessor or microcontroller. proper decoup- ling of the power supply is recommended. figure 4 shows the sensor output signal relative to pres- sure input. typical minimum and maximum output curves are shown for operation over temperature range of 0 to 85 c. the output will saturate outside of the specified pres- sure range. 0 10 20 30 50 60 70 80 90 100 200 210 0 output (volts) 5.0 4.5 4.0 3.5 3.0 max min 2.5 2.0 1.5 1.0 0.5 figure 4. output versus absolute pressure typ transfer function: v out = v s * (0.005 x p0.04) error v s = 5.1 vdc temp = 0 to 85 c 40 110 120 130 140 150 160 170 180 190 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

387 motorola sensor device data www.motorola.com/semiconductors ordering information device type options case no. mpx series order no. marking basic element absolute, element case 867 mpx4200a mpx4200a transfer function (mpx4200a) nominal transfer value: v out = v s x (0.005 x p 0.04) nominal transfer value: (pressure error x temp. factor x 0.005 x v s ) nominal transfer value: v s = 5.1 0.25 vdc temperature error band temp multiplier 40 3 18 1.56 0 to 85 1 +125 2 temperature in c 4.0 3.0 2.0 0.0 1.0 40 20 0 20 40 60 140 120 100 80 mpx4200a series temperature error factor pressure error band pressure in kpa pressure error (max) 20 kpa 4.2 (kpa) 40 kpa 2.4 (kpa) 160 kpa 2.4 (kpa) 200 kpa 3.2 (kpa) 6.0 4.0 2.0 2.0 4.0 6.0 60 80 100 120 140 160 pressure error (kpa) 180 20 40 200 mpx4200a series note: the temperature multiplier is a linear response from 0 c to 40 c and from 85 c to 125 c f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
388 motorola sensor device data www.motorola.com/semiconductors $"$ "##%" # " # %$ "##%" # " ! $ !"$%" !#$ "$ the motorola mpx4250a/mpxa4250a series manifold absolute pressure (map) sensor for engine control is designed to sense absolute air pressure within the intake manifold. this measurement can be used to compute the amount of fuel required for each cylinder. the mpx4250a/mpxa4250a series piezoresistive transducer is a stateoftheart monolithic silicon pressure sensor designed for a wide range of applications, particularly those employing a microcontroller or microprocessor with a/d inputs. this transducer combines advanced micromachining techniques, thinfilm metallization and bipolar processing to provide an accurate, highlevel analog output signal that is proportional to the applied pressure. the small form factor and high reliability of onchip integration make the motorola sensor a logical and economical choice for the automotive system engineer. features ? 1.5% maximum error over 0 to 85 c ? specifically designed for intake manifold absolute pressure sensing in engine control systems ? patented silicon shear stress strain gauge ? temperature compensated over 40 to +125 c ? offers reduction in weight and volume compared to existing hybrid modules ? durable epoxy unibody element or thermoplastic small outline, surface mount package ? ideal for nonautomotive applications application examples ? turbo boost engine control ? ideally suited for microprocessor or microcontroller based systems pins 4, 5, and 6 are no connects for unibody device pins 1, 5, 6, 7, and 8 are no connects for small outline package device figure 1. fully integrated pressure sensor schematic v s sensing element v out gnd thin film temperature compensation and gain stage #1 gain stage #2 and ground reference shift circuitry semiconductor technical data pin number note: pins 1, 5, 6, and 7 are internal device connections. do not connect to external circuitry or ground. pin 1 is noted by the notch in the lead. 1 2 3 n/c v s gnd 5 6 7 n/c n/c n/c port option case 482 port option case 482a 4v out 8 n/c small outline package

integrated pressure sensor 20 to 250 kpa (2.9 to 36.3 psi) 0.2 to 4.9 v output pin number note: pins 4, 5, and 6 are internal device connections. do not connect to external circuitry or ground. pin 1 is noted by the notch in the lead. basic chip carrier element case 867, style 1 port option case 867b, style 1 1 2 3 v out gnd v s 4 5 6 n/c n/c n/c unibody package rev 4 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

389 motorola sensor device data www.motorola.com/semiconductors maximum ratings (1) parametrics symbol value unit maximum pressure (2) (p1 > p2) p max 1000 kpa storage temperature t stg 40 to +125 c operating temperature t a 40 to +125 c notes: 1. t c = 25 c unless otherwise noted. 2. exposure beyond the specified limits may cause permanent damage or degradation to the device. operating characteristics (v s = 5.1 vdc, t a = 25 c unless otherwise noted, p1 > p2, decoupling circuit shown in figure 3 required to meet electrical specifications.) characteristic symbol min typ max unit pressure range (1) p op 20 e 250 kpa supply voltage (2) v s 4.85 5.1 5.35 vdc supply current i o e 7.0 10 madc minimum pressure offset (3) (0 to 85 c) @ v s = 5.1 volts v off 0.133 0.204 0.274 vdc full scale output (4) (0 to 85 c) @ v s = 5.1 volts v fso 4.826 4.896 4.966 vdc full scale span (5) (0 to 85 c) @ v s = 5.1 volts v fss e 4.692 e vdc accuracy (6) (0 to 85 c) e e e 1.5 %v fss sensitivity d v/ d p e 20 e mv/kpa response time (7) t r e 1.0 e msec output source current at full scale output l o + e 0.1 e madc warmup time (8) e e 20 e msec offset stability (9) e e 0.5 e %v fss notes: 1. 1.0 kpa (kilopascal) equals 0.145 psi. 2. device is ratiometric within this specified excitation range. 3. offset (v off ) is defined as the output voltage at the minimum rated pressure. 4. full scale output (v fso ) is defined as the output voltage at the maximum or full rated pressure. 5. full scale span (v fss ) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 6. accuracy (error budget) consists of the following: ? linearity: output deviation from a straight line relationship with pressure over the specified pressure range. ? temperature hysteresis: output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. ? pressure hysteresis: output deviation at any pressure within the specified range, when this pressure is cycled to and from the minimum or maximum rated pressure, at 25 c. ? tcspan: output deviation over the temperature range of 0 to 85 c, relative to 25 c. ? tcoffset: output deviation with minimum rated pressure applied, over the temperature range of 0 to 85 c, relative to 25 c. ? variation from nominal: the variation from nominal values, for offset or full scale span, as a percent of v fss , at 25 c. 7. response time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when s ubjected to a specified step change in pressure. 8. warmup is defined as the time required for the product to meet the specified output voltage after the pressure has been stab ilized. 9. offset stability is the product's output deviation when subjected to 1000 hours of pulsed pressure, temperature cycling with bias test. mechanical characteristics characteristics typ unit weight, basic element (case 867) 4.0 grams weight, small outline package (case 482) 1.5 grams f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

390 motorola sensor device data www.motorola.com/semiconductors figure 2. crosssectional diagram (not to scale) fluorosilicone die coat wire bond stainless steel metal cover rtv die bond die p1 p2 epoxy case lead frame sealed vacuum reference 1.0 f ips 470 pf output vs 5 v 0.01 f gnd vout figure 3. recommended power supply decoupling and output filtering. for additional output filtering, please refer to application note an1646. figure 2 illustrates the absolute pressure sensing chip in the basic chip carrier (case 867). a fluorosilicone gel iso- lates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the sensor diaphragm. the mpx4250 a/mpxa4250a series pressure sensor op- erating characteristics and internal reliability and qualifica- tion tests are based on use of dry air as the pressure media. media, other than dry air, may have adverse ef- fects on sensor performance and longterm reliability. contact the factory for information regarding media com- patibility in your application. figure 3 shows the recommended decoupling circuit for in- terfacing the output of the integrated sensor to the a/d input of a microprocessor or microcontroller. figure 4 shows the sensor output signal relative to pres- sure input. typical, minimum, and maximum output curves are shown for operation over temperature range of 0 to 85 c using the decoupling circuit shown in figure 3. the output will saturate outside of the specified pressure range. 0 output (volts) 5.0 4.5 4.0 3.5 3.0 pressure (ref: to sealed vacuum) in kpa max min 0 10 20 30 40 50 60 70 80 90 100 120 130 140 150 160 170 180 190 200 210 220 230 2.5 2.0 1.5 1.0 0.5 240 250 260 110 typ transfer function: v out = v s * (0.004 x p0.04) error v s = 5.1 vdc temp = 0 to 85 c figure 4. output versus absolute pressure f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

391 motorola sensor device data www.motorola.com/semiconductors transfer function nominal transfer value: v out = v s (p x 0.004 0.04) nominal transfer value: +/ (pressure error x temp. factor x 0.004 x v s ) nominal transfer value: v s = 5.1 v 0.25 vdc temperature error band temp multiplier 40 3 0 to 85 1 +125 3 temperature in c 4.0 3.0 2.0 0.0 1.0 40 20 0 20 40 60 140 120 100 80 temperature error factor pressure error band pressure error (max) 20 to 250 kpa 3.45 (kpa) note: the temperature multiplier is a linear response from 0 to 40 c and from 85 to 125 c. pressure (kpa) 75 100 125 150 175 200 225 25 50 250 4.0 3.0 2.0 1.0 0 1.0 2.0 3.0 4.0 5.0 5.0 0 pressure error (kpa) f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

392 motorola sensor device data www.motorola.com/semiconductors ordering information unibody package (case 867) the mpx4250a series pressure sensors are available in the basic element package or with pressure port fittings that provide mounting ease and barbed hose connections. device type/order no. options case no. marking mpx4250a basic element 867 mpx4250a mpx4250ap ported element 867b mpx4250ap ordering information small outline package (case 482) the mpxa4250a series pressure sensors are available in the basic element package or with a pressure port fitting. two packing options are offered for each type. device type/order no. case no. packing options device marking mpxa4250a6u 482 rails mpxa4250a mpxa4250a6t1 482 tape and reel mpxa4250a mpxa4250ac6u 482a rails mpxa4250a mpxa4250ac6t1 482a tape and reel mpxa4250a information for using the small outline package (case 482) minimum recommended footprint for surface mounted applications surface mount board layout is a critical portion of the total design. the footprint for the surface mount packages must be the correct size to ensure proper solder connection inter- face between the board and the package. with the correct fottprint, the packages will self align when subjected to a solder reflow process. it is always recommended to design boards with a solder mask layer to avoid bridging and short- ing between solder pads. 0.660 16.76 0.060 typ 8x 1.52 0.100 typ 8x 2.54 0.100 typ 8x 2.54 0.300 7.62 figure 5. sop footprint (case 482) inch mm scale 2:1 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
393 motorola sensor device data www.motorola.com/semiconductors $"$ "##%" # " ! $ !"$%" !#$ "$ the mpx4250d series piezoresistive transducer is a stateoftheart monolithic silicon pressure sensor designed for a wide range of applications, particularly those employing a microcontroller or microprocessor with a/d inputs. this transducer combines advanced micromachining techniques, thinfilm metallization, and bipolar processing to provide an accurate, highlevel analog output signal that is proportional to the applied pressure. the small form factor and high reliability of onchip integration make the motorola sensor a logical and economical choice for the automotive system engineer. features ? differential and gauge applications available ? 1.4% maximum error over 0 to 85 c ? patented silicon shear stress strain gauge ? temperature compensated over 40 to +125 c ? offers reduction in weight and volume compared to existing hybrid modules ? durable epoxy unibody element applications ? ideally suited for microprocessor or microcontrollerbased systems pins 4, 5 and 6 are no connects for unibody device figure 1. fully integrated pressure sensor schematic v s sensing element v out gnd thin film temperature compensation and gain stage #1 gain stage #2 and ground reference shift circuitry semiconductor technical data
integrated pressure sensor 0 to 250 kpa (0 to 36.3 psi) 0.2 to 4.9 volts output pin number note: pins 4, 5, and 6 are internal device connections. do not connect to external circuitry or ground. pin 1 is noted by the notch in the lead. basic chip carrier element case 867, style 1 gauge port option case 867b, style 1 1 2 3 v out gnd v s 4 5 6 n/c n/c n/c unibody package dual port option case 867c, style 1 rev 3 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

394 motorola sensor device data www.motorola.com/semiconductors maximum ratings (1) parametrics symbol value unit maximum pressure (2) (p1 > p2) p max 1000 kpa storage temperature t stg 40 to +125 c operating temperature t a 40 to +125 c notes: 1. t c = 25 c unless otherwise noted. 2. exposure beyond the specified limits may cause permanent damage or degradation to the device. operating characteristics (v s = 5.1 vdc, t a = 25 c unless otherwise noted, p1 > p2, decoupling circuit shown in figure 3 required to meet electrical specifications.) characteristic symbol min typ max unit pressure range (1) p op 0 e 250 kpa supply voltage (2) v s 4.85 5.1 5.35 vdc supply current i o e 7.0 10 madc minimum pressure offset (3) (0 to 85 c) @ v s = 5.1 volts v off 0.139 0.204 0.269 vdc full scale output (4) (0 to 85 c) @ v s = 5.1 volts v fso 4.844 4.909 4.974 vdc full scale span (5) (0 to 85 c) @ v s = 5.1 volts v fss e 4.705 e vdc accuracy (6) (0 to 85 c) e e e 1.4 %v fss sensitivity d v/ d p e 18.8 e mv/kpa response time (7) t r e 1.0 e msec output source current at full scale output l o + e 0.1 e madc warmup time (8) e e 20 e msec offset stability (9) e e 0.5 e %v fss notes: 1. 1.0 kpa (kilopascal) equals 0.145 psi. 2. device is ratiometric within this specified excitation range. 3. offset (v off ) is defined as the output voltage at the minimum rated pressure. 4. full scale output (v fso ) is defined as the output voltage at the maximum or full rated pressure. 5. full scale span (v fss ) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 6. accuracy (error budget) consists of the following: ? linearity: output deviation from a straight line relationship with pressure over the specified pressure range. ? temperature hysteresis: output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. ? pressure hysteresis: output deviation at any pressure within the specified range, when this pressure is cycled to and from the minimum or maximum rated pressure, at 25 c. ? tcspan: output deviation over the temperature range of 0 to 85 c, relative to 25 c. ? tcoffset: output deviation with minimum rated pressure applied, over the temperature range of 0 to 85 c, relative to 25 c. ? variation from nominal: the variation from nominal values, for offset or full scale span, as a percent of v fss , at 25 c. 7. response time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when s ubjected to a specified step change in pressure. 8. warmup is defined as the time required for the product to meet the specified output voltage after the pressure has been stab ilized. 9. offset stability is the product's output deviation when subjected to 1000 hours of pulsed pressure, temperature cycling with bias test. mechanical characteristics characteristics typ unit weight, basic element (case 867) 4.0 grams f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

395 motorola sensor device data www.motorola.com/semiconductors figure 2. crosssectional diagram (not to scale) fluorosilicone die coat wire bond lead frame die stainless steel metal cover rtv die bond p1 p2 epoxy case 1.0 f ips 470 pf output vs 5 v 0.01 f gnd vout figure 3. recommended power supply decoupling and output filtering. for additional output filtering, please refer to application note an1646. figure 2 illustrates the differential/gauge pressure sensing chip in the basic chip carrier (case 867). a fluorosilicone gel isolates the die surface and wire bonds from the environ- ment, while allowing the pressure signal to be transmitted to the sensor diaphragm. the mpx4250d series pressure sensor operating charac- teristics and internal reliability and qualification tests are based on use of dry air as the pressure media. media, other than dry air, may have adverse effects on sensor performance and longterm reliability. contact the factory for information regarding media compatibility in your application. figure 3 shows the recommended decoupling circuit for in- terfacing the output of the integrated sensor to the a/d input of a microprocessor or microcontroller. figure 4 shows the sensor output signal relative to pres- sure input. typical, minimum, and maximum output curves are shown for operation over a temperature range of 0 to 85 c using the decoupling circuit shown in figure 3. the output will saturate outside of the specified pressure range. 0 output (volts) 5.0 4.5 4.0 3.5 3.0 pressure in kpa max min 0 10 20 30 40 50 60 70 80 100 110 120 130 140 150 160 170 180 190 200 210 2.5 2.0 1.5 1.0 0.5 figure 4. output versus differential pressure 250 260 90 typ transfer function: v out = v s * (0.00369*p + 0.04) error v s = 5.1 vdc temp = 0 to 85 c f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

396 motorola sensor device data www.motorola.com/semiconductors ordering information the mpx4250d series silicon pressure sensors are available in the basic element package or with pressure port fittings that provide mounting ease and barbed hose connections. device type/order no. options case no. marking mpx4250d basic element 867 mpx4250d mpx4250gp gauge ported element 867b mpx4250gp mpx4250dp dual ported element 867c mpx4250dp transfer function (mpx4250d) nominal transfer value: v out = v s x (0.00369 x p + 0.04) nominal transfer value: (pressure error x temp. factor x 0.00369 x v s ) nominal transfer value: v s = 5.1 0.25 vdc temperature error band temp multiplier 40 3 0 to 85 1 +125 3 temperature in c 4.0 3.0 2.0 0.0 1.0 40 20 0 20 40 60 140 120 100 80 temperature error factor pressure error band pressure (kpa) pressure error (max) 0 to 250 kpa 3.45 kpa 75 100 125 150 175 200 225 25 50 250 note: the temperature multiplier is a linear response from 0 to 40 c and from 85 to 125 c. 4.0 3.0 2.0 1.0 0 1.0 2.0 3.0 4.0 5.0 5.0 0 pressure error (kpa) f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
397 motorola sensor device data www.motorola.com/semiconductors $"$ "##%" # " ! $ !"$%" !#$ "$ the mpx5010/mpxv5010g series piezoresistive transducers are stateoftheart monolithic silicon pres- sure sensors designed for a wide range of applications, but particularly those employing a microcontroller or micro- processor with a/d inputs. this transducer combines advanced micromachining techniques, thinfilm metal- lization, and bipolar processing to provide an accurate, high level analog output signal that is proportional to the applied pressure. features ? 5.0% maximum error over 0 to 85 c ? ideally suited for microprocessor or microcontroller based systems ? durable epoxy unibody and thermoplastic (pps) surface mount package ? temperature compensated over 40 to +125 c ? patented silicon shear stress strain gauge ? available in differential and gauge configurations ? available in surface mount (smt) or throughhole (dip) configurations application examples ? hospital beds ? hvac ? respiratory systems ? process control figure 1. fully integrated pressure sensor schematic v s sensing element v out gnd thin film temperature compensation and gain stage #1 gain stage #2 and ground reference shift circuitry pins 1 and 5 through 8 are no connects for surface mount package pins 4, 5, and 6 are no connects for unibody package semiconductor technical data mpxv5010gc7u case 482c mpxv5010gc6u case 482a mpxv5010g6u case 482
integrated pressure sensor 0 to 10 kpa (0 to 1.45 psi) 0.2 to 4.7 v output small outline package pin number note: pins 1, 5, 6, 7, and 8 are internal device connections. do not connect to external circuitry or ground. pin 1 is noted by the notch in the lead. 1 2 3 n/c v s gnd 5 6 7 n/c n/c n/c 4v out 8 n/c unibody package mpx5010d case 867 mpx5010dp case 867c pin number note: pins 4, 5, and 6 are internal device connections. do not connect to external circuitry or ground. pin 1 is noted by the notch in the lead. 1 2 3 v out gnd v s 4 5 6 n/c n/c n/c mpx5010gs case 867e motorola preferred device mpxv5010dp case 1351 mpxv5010gp case 1369 rev 9 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

398 motorola sensor device data www.motorola.com/semiconductors maximum ratings (note) parametrics symbol value unit maximum pressure (p1 > p2) p max 75 kpa storage temperature t stg 40 to +125 c operating temperature t a 40 to +125 c note: exposure beyond the specified limits may cause permanent damage or degradation to the device. operating characteristics (v s = 5.0 vdc, t a = 25 c unless otherwise noted, p1 > p2. decoupling circuit shown in figure 3 required to meet specification.) characteristic symbol min typ max unit pressure range (1) p op 0 e 10 kpa supply voltage (2) v s 4.75 5.0 5.25 vdc supply current i o e 5.0 10 madc minimum pressure offset (3) (0 to 85 c) @ v s = 5.0 volts v off 0 0.2 0.425 vdc full scale output (4) (0 to 85 c) @ v s = 5.0 volts v fso 4.475 4.7 4.925 vdc full scale span (5) (0 to 85 c) @ v s = 5.0 volts v fss 4.275 4.5 4.725 vdc accuracy (6) (0 to 85 c) e e e 5.0 %v fss sensitivity v/p e 450 e mv/kpa response time (7) t r e 1.0 e ms output source current at full scale output i o+ e 0.1 e madc warmup time (8) e e 20 e ms offset stability (9) e e 0.5 e %v fss notes: 1. 1.0 kpa (kilopascal) equals 0.145 psi. 2. device is ratiometric within this specified excitation range. 3. offset (v off ) is defined as the output voltage at the minimum rated pressure. 4. full scale output (v fso ) is defined as the output voltage at the maximum or full rated pressure. 5. full scale span (v fss ) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 6. accuracy (error budget) consists of the following: ? linearity: output deviation from a straight line relationship with pressure over the specified pressure range. ? temperature hysteresis: output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. ? pressure hysteresis: output deviation at any pressure within the specified range, when this pressure is cycled to and from the minimum or maximum rated pressure, at 25 c. ? tcspan: output deviation over the temperature range of 0 to 85 c, relative to 25 c. ? tcoffset: output deviation with minimum rated pressure applied, over the temperature range of 0 to 85 c, relative to 25 c. ? variation from nominal: the variation from nominal values, for offset or full scale span, as a percent of v fss , at 25 c. 7. response time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when s ubjected to a specified step change in pressure. 8. warmup time is defined as the time required for the product to meet the specified output voltage after the pressure has been stabilized. 9. offset stability is the product's output deviation when subjected to 1000 hours of pulsed pressure, temperature cycling with bias test. mechanical characteristics characteristics typ unit weight, basic element (case 867) 4.0 grams weight, basic element (case 482) 1.5 grams f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

399 motorola sensor device data www.motorola.com/semiconductors onchip temperature compensation, calibration and signal conditioning the performance over temperature is achieved by integrat- ing the shearstress strain gauge, temperature compensa- tion, calibration and signal conditioning circuitry onto a single monolithic chip. figure 2 illustrates the differential or gauge configuration in the basic chip carrier (case 482). a fluorosilicone gel isolates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the sensor diaphragm. the mpx5010 and mpxv5010g series pressure sensor operating characteristics, and internal reliability and qualifi- cation tests are based on use of dry air as the pressure me- dia. media, other than dry air, may have adverse effects on sensor performance and longterm reliability. contact the factory for information regarding media compatibility in your application. figure 3 shows the recommended decoupling circuit for in- terfacing the integrated sensor to the a/d input of a micropro- cessor or microcontroller. proper decoupling of the power supply is recommended. figure 4 shows the sensor output signal relative to pres- sure input. typical, minimum, and maximum output curves are shown for operation over a temperature range of 0 to 85 c using the decoupling circuit shown in figure 4. the output will saturate outside of the specified pressure range. figure 2. crosssectional diagram sop (not to scale) figure 3. recommended power supply decoupling and output filtering. for additional output filtering, please refer to application note an1646. 1.0 f ips 470 pf output vs 5 v 0.01 f gnd vout fluorosilicone gel die coat wire bond differential sensing element thermoplastic case stainless steel cap lead frame p1 p2 die bond die differential pressure (kpa) 5.0 4.0 3.0 2.0 0 11 7 3 0 output (v) 9 5 4.5 3.5 2.5 1.5 1 1.0 0.5 10 6 28 4 transfer function: v out = v s *(0.09*p+0.04) error v s = 5.0 vdc temp = 0 to 85 c typical max min figure 4. output versus pressure differential f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

3100 motorola sensor device data www.motorola.com/semiconductors transfer function (mpx5010, mpxv5010g) nominal transfer value: v out = v s x (0.09 x p + 0.04) nominal transfer value: (pressure error x temp. factor x 0.09 x v s ) nominal transfer value: v s = 5.0 v 0.25 vdc temperature error band temp multiplier 40 3 0 to 85 1 +125 3 temperature in c 4.0 3.0 2.0 0.0 1.0 40 20 0 20 40 60 140 120 100 80 mpx5010, mpxv5010g series temperature error factor pressure error band note: the temperature multiplier is a linear response from 0 to 40 c and from 85 to 125 c. pressure (kpa) 0.5 0.4 0.2 0.3 0.4 0.5 0 123456 7 pressure error (max) 0 to 10 kpa 0.5 kpa 89 0 0.3 0.1 0.2 0.1 10 pressure error (kpa) f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

3101 motorola sensor device data www.motorola.com/semiconductors pressure (p1)/vacuum (p2) side identification table motorola designates the two sides of the pressure sensor as the pressure (p1) side and the vacuum (p2) side. the pressure (p1) side is the side containing fluoro silicone gel which protects the die from harsh media. the motorola mpx pressure sensor is designed to operate with positive differen- tial pressure applied, p1 > p2. the pressure (p1) side may be identified by using the table below: part number case type pressure (p1) side identifier mpx5010d 867 c stainless steel cap mpx5010dp 867c side with part marking mpx5010gp 867b side with port attached mpx5010gs 867e side with port attached mpx5010gsx 867f side with port attached mpxv5010g6u 482 stainless steel cap mpxv5010g7u 482b stainless steel cap mpxv5010gc6u/t1 482a side with port attached mpxv5010gc7u 482c side with port attached mpxv5010gp 1369 side with port attached mpxv5010dp 1351 side with part marking ordering information e unibody package (mpx5010 series) mpx series device type options case type order number device marking basic element differential 867 mpx5010d mpx5010d ported elements differential, dual port 867c mpx5010dp mpx5010dp gauge 867b mpx5010gp mpx5010gp gauge, axial 867e mpx5010gs mpx5010d gauge, axial pc mount 867f mpx5010gsx mpx5010d ordering information e small outline package (mpxv5010g series) device type options case no. mpx series order no. packing options marking basic elements gauge, element only, smt 482 mpxv5010g6u rails mpxv5010g gauge, element only, dip 482b mpxv5010g7u rails mpxv5010g ported elements gauge, axial port, smt 482a mpxv5010gc6u rails mpxv5010g gauge, axial port, dip 482c mpxv5010gc7u rails mpxv5010g gauge, axial port, smt 482a mpxv5010gc6t1 tape and reel mpxv5010g gauge, side port, smt 1369 mpxv5010gp trays mpxv5010g differential, dual port, smt 1351 mpxv5010dp trays mpxv5010g f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

3102 motorola sensor device data www.motorola.com/semiconductors minimum recommended footprint for surface mounted applications surface mount board layout is a critical portion of the total design. the footprint for the surface mount packages must be the correct size to ensure proper solder connection inter- face between the board and the package. with the correct footprint, the packages will self align when subjected to a solder reflow process. it is always recommended to design boards with a solder mask layer to avoid bridging and short- ing between solder pads. 0.660 16.76 0.060 typ 8x 1.52 0.100 typ 8x 2.54 0.100 typ 8x 2.54 0.300 7.62 figure 5. sop footprint (case 482) inch mm scale 2:1 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3103 motorola sensor device data www.motorola.com/semiconductors
#!# !""$! "! # !#$! "# !# the mpx5050/mpxv5050g series piezoresistive transducer is a stateoftheart monolithic silicon pressure sensor designed for a wide range of applications, but particularly those employing a microcontroller or microprocessor with a/d inputs. this patented, single element transducer combines advanced micromachining techniques, thinfilm metallization, and bipolar processing to provide an accurate, high level analog output signal that is proportional to the applied pressure. features ? 2.5% maximum error over 0 to 85 c ? ideally suited for microprocessor or microcontrollerbased systems ? temperature compensated over 40 to +125 c ? patented silicon shear stress strain gauge ? durable epoxy unibody element ? easytouse chip carrier option figure 1. fully integrated pressure sensor schematic v s sensing element gnd thin film temperature compensation and gain stage #1 gain stage #2 and ground reference shift circuitry v out pins 4, 5, and 6 are no connects for unibody device pins 1, 5, 6, 7, and 8 are no connects for small outline package device semiconductor technical data
integrated pressure sensor 0 to 50 kpa (0 to 7.25 psi) 0.2 to 4.7 volts output pin number note: pins 4, 5, and 6 are internal device connections. do not connect to external circuitry or ground. pin 1 is noted by the notch in the lead. mpx5050d case 867 mpx5050dp case 867c 1 2 3 v out gnd v s 4 5 6 n/c n/c n/c mpx5050gp case 867b unibody package small outline package surface mount mpxv5050dp case 1351 mpxv5050gp case 1369 pin number 1 2 3 n/c v s gnd 5 6 7 n/c n/c n/c 4v out 8 n/c note: pins 1, 5, 6, 7, and 8 are internal device connections. do not connect to external circuitry or ground. pin 1 is noted by the notch in the lead. motorola preferred device rev 6 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

3104 motorola sensor device data www.motorola.com/semiconductors maximum ratings (note) parametrics symbol value unit maximum pressure (p1 > p2) p max 200 kpa storage temperature t stg 40 to +125 c operating temperature t a 40 to +125 c note: exposure beyond the specified limits may cause permanent damage or degradation to the device. operating characteristics (v s = 5.0 vdc, t a = 25 c unless otherwise noted, p1 > p2. decoupling circuit shown in figure 4 required to meet electrical specifications.) characteristic symbol min typ max unit pressure range (1) p op 0 e 50 kpa supply voltage (2) v s 4.75 5.0 5.25 vdc supply current i o e 7.0 10.0 madc minimum pressure offset (3) (0 to 85 c) @ v s = 5.0 volts v off 0.088 0.20 0.313 vdc full scale output (4) (0 to 85 c) @ v s = 5.0 volts v fso 4.587 4.70 4.813 vdc full scale span (5) (0 to 85 c) @ v s = 5.0 volts v fss e 4.50 e vdc accuracy (6) e e e 2.5 %v fss sensitivity v/p e 90 e mv/kpa response time (7) t r e 1.0 e ms output source current at full scale output i o + e 0.1 e madc warmup time (8) e e 20 e ms offset stability (9) e e 0.5 e %v fss notes: 1. 1.0kpa (kilopascal) equals 0.145 psi. 2. device is ratiometric within this specified excitation range. 3. offset (v off ) is defined as the output voltage at the minimum rated pressure. 4. full scale output (v fso ) is defined as the output voltage at the maximum or full rated pressure. 5. full scale span (v fss ) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 6. accuracy (error budget) consists of the following: ? linearity: output deviation from a straight line relationship with pressure over the specified pressure range. ? temperature hysteresis: output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. ? pressure hysteresis: output deviation at any pressure within the specified range, when this pressure is cycled to and from minimum or maximum rated pressure at 25 c. ? tcspan: output deviation over the temperature range of 0 to 85 c, relative to 25 c. ? tcoffset: output deviation with minimum pressure applied, over the temperature range of 0 to 85 c, relative to 25 c. ? variation from nominal: the variation from nominal values, for offset or full scale span, as a percent of v fss at 25 c. 7. response time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when s ubjected to a specified step change in pressure. 8. warmup time is defined as the time required for the product to meet the specified output voltage after the pressure has been stabilized. 9. offset stability is the product's output deviation when subjected to 1000 hours of pulsed pressure, temperature cycling with bias test. mechanical characteristics characteristics typ unit weight, basic element (case 867) 4.0 grams weight, basic element (case 1369) 1.5 grams f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

3105 motorola sensor device data www.motorola.com/semiconductors figure 3 illustrates the differential/gauge sensing chip in the basic chip carrier (case 867). a fluorosilicone gel isolates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the sensor diaphragm. the mpx5050/mpxv5050g series pressure sensor oper- ating characteristics, and internal reliability and qualification tests are based on use of dry air as the pressure media. me- dia, other than dry air, may have adverse effects on sensor performance and longterm reliability. contact the factory for information regarding media compatibility in your application. figure 2 shows the sensor output signal relative to pres- sure input. typical, minimum, and maximum output curves are shown for operation over a temperature range of 0 to 85 c using the decoupling circuit shown in figure 4 . the output will saturate outside of the specified pressure range. figure 4 shows the recommended decoupling circuit for interfacing the output of the integrated sensor to the a/d in- put of a microprocessor or microcontroller. proper decoup- ling of the power supply is recommended. figure 2. output versus pressure differential max differential pressure (kpa) 5.0 4.0 3.0 2.0 0 55 35 15 0 output (v) 45 25 4.5 3.5 2.5 1.5 5 transfer function: v out = v s *(0.018*p+0.04) error v s = 5.0 vdc temp = 0 to 85 c 1.0 0.5 50 30 10 40 20 min typical figure 3. crosssectional diagram (not to scale) fluoro silicone gel die coat wire bond lead frame die stainless steel metal cover epoxy plastic case differential/gauge element die bond p1 p2 figure 4. recommended power supply decoupling and output filtering. for additional output filtering, please refer to application note an1646. 1.0 f ips 470 pf output vs 5 v 0.01 f gnd vout f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

3106 motorola sensor device data www.motorola.com/semiconductors nominal transfer value: v out = v s (p x 0.018 + 0.04) +/ (pressure error x temp. factor x 0.018 x v s ) v s = 5.0 v 0.25 vdc transfer function 0.0 40 20 0 20 40 60 140 120 100 80 temperature error band 40 3 0 to 85 1 +125 3 temperature in c 4.0 3.0 2.0 1.0 mpx5050/mpxv5050g series temp multiplier temperature error factor note: the temperature multiplier is a linear response from 0 to 40 c and from 85 to 125 c. pressure error band error limits for pressure pressure (in kpa) 3.0 2.0 1.0 1.0 2.0 3.0 0.0 01020304050 60 pressure error (kpa) pressure error (max) 0 to 50 kpa 1.25 kpa f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

3107 motorola sensor device data www.motorola.com/semiconductors pressure (p1) / vacuum (p2) side identification table motorola designates the two sides of the pressure sensor as the pressure (p1) side and the vacuum (p2) side. the pressure (p1) side is the side containing fluorosilicone gel which protects the die from harsh media. the motorola mpx pressure sensor is designed to operate with positive differen- tial pressure applied, p1 > p2. the pressure (p1) side may be identified by using the table below: part number case type pressure (p1) side identifier mpx5050d 867 stainless steel cap mpx5050dp 867c side with part marking mpx5050gp 867b side with port attached mpxv5050gp 1369 side with port attached mpxv5050dp 1351 side with part marking ordering information e unibody package (mpx5050 series) mpx series device type options case type order number device marking basic element differential 867 mpx5050d mpx5050d ported elements differential dual ports 867c mpx5050dp mpx5050dp gauge 867b mpx5050gp mpx5050gp ordering information e small outline package (mpxv5050g series) device type options case no. mpx series order no. packing options marking ported elements side port 1369 mpxv5050gp trays mpxv5050g dual port 1351 mpxv5050dp trays mpxv5050g f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3108 motorola sensor device data www.motorola.com/semiconductors
" " !!# ! " "# !" " the mpx5100 series piezoresistive transducer is a stateoftheart monolithic silicon pressure sensor designed for a wide range of applications, but particularly those employing a microcontroller or microprocessor with a/d inputs. this patented, single element transducer c ombines advanced micromachining techniques, thinfilm metalliza- tion, and bipolar processing to provide an accurate, high level analog output signal that is proportional to the applied pressure. features ? 2.5% maximum error over 0 to 85 c ? ideally suited for microprocessor or microcontrollerbased systems ? patented silicon shear stress strain gauge ? available in absolute, differential and gauge configurations ? durable epoxy unibody element ? easytouse chip carrier option v s sensing element gnd thin film temperature compensation and gain stage #1 gain stage #2 and ground reference shift circuitry pins 4, 5 and 6 are no connects figure 1. fully integrated pressure sensor schematic v out semiconductor technical data
integrated pressure sensor 0 to 100 kpa (0 to 14.5 psi) 15 to 115 kpa (2.18 to 16.68 psi) 0.2 to 4.7 volts output pin number note: pins 4, 5, and 6 are internal device connections. do not connect to external circuitry or ground. pin 1 is noted by the notch in the lead. mpx5100d case 867 mpx5100dp case 867c 1 2 3 v out gnd v s 4 5 6 n/c n/c n/c mpx5100gsx case 867f rev 7 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

3109 motorola sensor device data www.motorola.com/semiconductors maximum ratings (note) parametrics symbol value unit maximum pressure (p1 > p2) p max 400 kpa storage temperature t stg 40 to +125 c operating temperature t a 40 to +125 c note: exposure beyond the specified limits may cause permanent damage or degradation to the device. operating characteristics (v s = 5.0 vdc, t a = 25 c unless otherwise noted, p1 > p2. decoupling circuit shown in figure 4 required to meet electrical specifications.) characteristic symbol min typ max unit pressure range (1) gauge, differential: mpx5100d absolute: mpx5100a p op 0 15 e e 100 115 kpa supply voltage (2) v s 4.75 5.0 5.25 vdc supply current i o e 7.0 10 madc minimum pressure offset (3) (0 to 85 c) @ v s = 5.0 volts v off 0.088 0.20 0.313 vdc full scale output (4) differential and absolute (0 to 85 c) @ v s = 5.0 volts vacuum (10) v fso 4.587 3.688 4.700 3.800 4.813 3.913 vdc full scale span (5) differential and absolute (0 to 85 c) @ v s = 5.0 volts vacuum (10) v fss e e 4.500 3.600 e e vdc accuracy (6) e e e 2.5 %v fss sensitivity v/p e 45 e mv/kpa response time (7) t r e 1.0 e ms output source current at full scale output i o+ e 0.1 e madc warmup time (8) e e 20 e ms offset stability (9) e e 0.5 e %v fss notes: 1. 1.0kpa (kilopascal) equals 0.145 psi. 2. device is ratiometric within this specified excitation range. 3. offset (v off ) is defined as the output voltage at the minimum rated pressure. 4. full scale output (v fso ) is defined as the output voltage at the maximum or full rated pressure. 5. full scale span (v fss ) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 6. accuracy (error budget) consists of the following: ? linearity: output deviation from a straight line relationship with pressure over the specified pressure range. ? temperature hysteresis: output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. ? pressure hysteresis: output deviation at any pressure within the specified range, when this pressure is cycled to and from minimum or maximum rated pressure at 25 c. ? tcspan: output deviation over the temperature range of 0 to 85 c, relative to 25 c. ? tcoffset: output deviation with minimum pressure applied, over the temperature range of 0 to 85 c, relative to 25 c. ? variation from nominal: the variation from nominal values, for offset or full scale span, as a percent of v fss at 25 c. 7. response time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when s ubjected to a specified step change in pressure. 8. warmup time is defined as the time required for the product to meet the specified output voltage after the pressure has been stabilized. 9. offset stability is the product's output deviation when subjected to 1000 hours of pulsed pressure, temperature cycling with bias test. mechanical characteristics characteristics typ unit weight, basic element (case 867) 4.0 grams f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

3110 motorola sensor device data www.motorola.com/semiconductors onchip temperature compensation, calibration and signal conditioning figure 2. output versus pressure differential figure 2 shows the sensor output signal relative to pressure input. typical, minimum, and maximum out- put curves are shown for operation over a temperature range of 0 to 85 c using the decoupling circuit shown in figure 4. the output will saturate outside of the spe- cified pressure range. output (v) 5 4.5 4 3.5 3 pressure (kpa) typ max min 0 10 20 30 40 50 60 70 80 90 100 2.5 2 1.5 1 0.5 0 110 v s = 5 vdc t a = 25 c mpx5100 span range (typ) output range (typ) offset (typ) fluoro s i l i cone gel die coat wire bond lead frame die sta i nless steel metal cover epoxy plastic case differential/gauge element die bond fluoro silicone gel die coat wire bond lead frame die sta i nless steel metal cover epoxy plastic case die bond absolute element figure 3. crosssectional diagrams (not to scale) figure 3 illustrates both the differential/gauge and the absolute sensing chip in the basic chip carrier (case 867). a fluorosilicone gel isolates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the sensor diaphragm. the mpx5100 series pressure sensor operating char- acteristics, and internal reliability and qualification tests are based on use of dry air as the pressure media. media, other than dry air, may have adverse effects on sensor performance and longterm reliability. contact the fac- tory for information regarding media compatibility in your application. figure 4 shows the recommended decoupling circuit for interfacing the output of the integrated sensor to the a/d in- put of a microprocessor or microcontroller. proper decoup- ling of the power supply is recommended. figure 4. recommended power supply decoupling and output filtering. for additional output filtering, please refer to application note an1646. 1.0 f ips 470 pf output vs 5 v 0.01 f gnd vout f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

3111 motorola sensor device data www.motorola.com/semiconductors nominal transfer value: v out = v s (p x 0.009 + 0.04) +/ (pressure error x temp. mult. x 0.009 x v s ) v s = 5.0 v 5% p kpa transfer function (mpx5100d, mpx5100g) temperature error multiplier break points temp multiplier temperature in c 4.0 3.0 2.0 0.0 1.0 40 20 0 20 40 60 130 120 100 80 mpx5100d series pressure error band pressure in kpa 3.0 2.0 1.0 1.0 2.0 3.0 0.0 0 20 40 60 80 100 120 pressure error (max) 0 to 100 kpa 2.5 kpa 40 3 0 to 85 1 +125 3 note: the temperature multiplier is a linear response from 0 to 40 c and from 85 to 125 c. 140 error (kpa) error limits for pressure mpx5100d series f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

3112 motorola sensor device data www.motorola.com/semiconductors nominal transfer value: v out = v s (p x 0.009 0.095) +/ (pressure error x temp. mult. x 0.009 x v s ) v s = 5.0 v 5% p kpa transfer function (mpx5100a) temperature error multiplier break points temp multiplier temperature in c 4.0 3.0 2.0 0.0 1.0 40 20 0 20 40 60 130 120 100 80 mpx5100a series pressure error band 40 3 0 to 85 1 +125 3 140 note: the temperature multiplier is a linear response from 0 to 40 c and from 85 to 125 c. pressure in kpa 3.0 2.0 1.0 1.0 2.0 3.0 0.0 0 20 40 60 80 100 130 pressure error (max) 15 to 115 kpa 2.5 kpa error (kpa) error limits for pressure mpx5100a series f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

3113 motorola sensor device data www.motorola.com/semiconductors pressure (p1)/vacuum (p2) side identification table motorola designates the two sides of the pressure sensor as the pressure (p1) side and the vacuum (p2) side. the pressure (p1) side is the side containing fluoro silicone gel which protects the die from harsh media. the motorola mpx pressure sensor is designed to operate with positive differen- tial pressure applied, p1 > p2. the pressure (p1) side may be identified by using the table below: part number case type pressure (p1) side identifier mpx5100a, mpx5100d 867 stainless steel cap mpx5100dp 867c side with part marking mpx5100ap, mpx5100gp 867b side with port attached mpx5100gsx 867f side with port attached ordering information: the mpx5100 pressure sensor is available in absolute, differential, and gauge configurations. devices are available in the basic element package or with pressure port fittings that provide printed circuit board mounting ease and barbed hose pres- sure connections. mpx series device name options case type order number device marking basic element absolute 867 mpx5100a mpx5100a differential 867 mpx5100d mpx5100d ported elements differential dual ports 867c mpx5100dp mpx5100dp absolute, single port 867b mpx5100ap mpx5100ap gauge, single port 867b mpx5100gp mpx5100gp gauge, axial pc mount 867f mpx5100gsx mpx5100d f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3114 motorola sensor device data www.motorola.com/semiconductors ! " the mpx53/mpxv53gc series silicon piezoresistive pressure sensors provide a very accurate and linear voltage output e directly proportional to the applied pressure. these standard, low cost, uncompensated sensors permit manufacturers to design and add their own external temperature compensating and signal conditioning networks. compensation techniques are simplified because of the predictability of motorola's single element strain gauge design. features ? low cost ? patented silicon shear stress strain gauge design ? ratiometric to supply voltage ? easy to use chip carrier package options ? 60 mv span (typ) ? differential and gauge options application examples ? air movement control ? environmental control systems ? level indicators ? leak detection ? medical instrumentation ? industrial controls ? pneumatic control systems ? robotics figure 1 shows a schematic of the internal circuitry on the standalone pressure sensor chip. voltage output versus applied differential pressure the differential voltage output of the sensor is directly proportional to the differential pressure applied. the output voltage of the differential or gauge sensor increases with increasing pressure applied to the pressure side (p1) relative to the vacuum side (p2). similarly, output voltage increases as increasing vacuum is applied to the vacuum side (p2) relative to the pressure side (p1). replaces mpx50/d
semiconductor technical data mpx53d case 344 mpx53gp case 344b 0 to 50 kpa (0 7.25 psi) 60 mv full scale span (typical) note: pin 1 is the notched pin. pin number 1 2 gnd +v out 3 4 v s v out small outline package mpxv53gc6u case 482a mpxv53gc7u case 482c pin number 1 2 3 gnd +v out v s 5 6 7 n/c n/c n/c 4v out 8 n/c unibody package note: pin 1 is the notched pin. mpx53dp case 344c figure 1. uncompensated pressure sensor schematic sensor + v out v out + v s gnd rev 2 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

3115 motorola sensor device data www.motorola.com/semiconductors maximum ratings (note) rating symbol value unit maximum pressure (p1 > p2) p max 200 kpa storage temperature t stg 40 to +125 c operating temperature t a 40 to +125 c note: exposure beyond the specified limits may cause permanent damage or degradation to the device. operating characteristics (v s = 3.0 vdc, t a = 25 c unless otherwise noted, p1 > p2) characteristic symbol min typ max unit pressure range (1) p op 0 e 50 kpa supply voltage (2) v s e 3.0 6.0 vdc supply current i o e 6.0 e madc full scale span (3) v fss 45 60 90 mv offset (4) v off 0 20 35 mv sensitivity d v/ d p e 1.2 e mv/kpa linearity (5) e 0.6 e 0.4 %v fss pressure hysteresis (5) (0 to 50 kpa) e e 0.1 e %v fss temperature hysteresis (5) ( 40 c to +125 c) e e 0.5 e %v fss temperature coefficient of full scale span (5) tcv fss 0.22 e 0.16 %v fss / c temperature coefficient of offset (5) tcv off e 15 e m v/ c temperature coefficient of resistance (5) tcr 0.31 e 0.37 %z in / c input impedance z in 355 e 505 w output impedance z out 750 e 1875 w response time (6) (10% to 90%) t r e 1.0 e ms warmup e e 20 e ms offset stability (7) e e 0.5 e %v fss notes: 1. 1.0 kpa (kilopascal) equals 0.145 psi. 2. device is ratiometric within this specified excitation range. operating the device above the specified excitation range may induce additional error due to device selfheating. 3. full scale span (v fss ) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 4. offset (v off ) is defined as the output voltage at the minimum rated pressure. 5. accuracy (error budget) consists of the following: ? linearity: output deviation from a straight line relationship with pressure, using end point method, over the specified pressure range. ? temperature hysteresis: output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. ? pressure hysteresis: output deviation at any pressure within the specified range, when this pressure is cycled to and from the minimum or maximum rated pressure, at 25 c. ? tcspan: output deviation at full rated pressure over the temperature range of 0 to 85 c, relative to 25 c. ? tcoffset: output deviation with minimum rated pressure applied, over the temperature range of 0 to 85 c, relative to 25 c. ? tcr: z in deviation with minimum rated pressure applied, over the temperature range of 40 c to +125 c, relative to 25 c. 6. response time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when s ubjected to a specified step change in pressure. 7. offset stability is the product's output deviation when subjected to 1000 hours of pulsed pressure, temperature cycling with bias test. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

3116 motorola sensor device data www.motorola.com/semiconductors temperature compensation figure 2 shows the typical output characteristics of the mpx53/mpxv53gc series over temperature. the piezoresistive pressure sensor element is a semicon- ductor device which gives an electrical output signal propor- tional to the pressure applied to the device. this device uses a unique transverse voltage diffused semiconductor strain gauge which is sensitive to stresses produced in a thin sili- con diaphragm by the applied pressure. because this strain gauge is an integral part of the silicon diaphragm, there are no temperature effects due to differ- ences in the thermal expansion of the strain gauge and the diaphragm, as are often encountered in bonded strain gauge pressure sensors. however, the properties of the strain gauge itself are temperature dependent, requiring that the device be temperature compensated if it is to be used over an extensive temperature range. temperature compensation and offset calibration can be achieved rather simply with additional resistive components, or by designing your system using the mpx2053 series sensors. several approaches to external temperature compensa- tion over both 40 to +125 c and 0 to + 80 c ranges are presented in motorola applications note an840. linearity linearity refers to how well a transducer's output follows the equation: v out = v off + sensitivity x p over the operating pressure range (see figure 3). there are two basic methods for calculating nonlinearity: (1) end point straight line fit or (2) a least squares best line fit. while a least squares fit gives the abest caseo linearity error (lower numerical value), the calculations required are burdensome. conversely, an end point fit will give the aworst caseo error (often more desirable in error budget calculations) and the calculations are more straightforward for the user. motoro- la's specified pressure sensor linearities are based on the end point straight line method measured at the midrange pressure. figure 2. output versus pressure differential figure 3. linearity specification comparison figure 4. crosssectional diagram (not to scale) silicone die coat wire bond lead frame die stainless steel metal cover epoxy case rtv die bond p1 p2 100 012 345 678 10 20 30 40 50 psi kpa 0 out p ut ( mv dc) pressure differential offset (typ) offset (v off ) 70 output (mvdc) 60 50 40 30 20 10 0 0 max p op span (v fss ) pressure (kpa) actual theoretical linearity 90 80 70 60 50 40 30 20 10 0 span range (typ) 40 c + 125 c +25 c mpx53 v s = 3 vdc p1 > p2 figure 4 illustrates the differential or gauge configuration in the unibody chip carrier (case 344). a silicone gel isolates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the silicon diaphragm. the mpx53/mpxv53gc series pressure sensor operating characteristics and internal reliability and qualification tests are based on use of dry air as the pressure media. media other than dry air may have adverse effects on sensor perfor- mance and long term reliability. contact the factory for in- formation regarding media compatibility in your application. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

3117 motorola sensor device data www.motorola.com/semiconductors pressure (p1)/vacuum (p2) side identification table motorola designates the two sides of the pressure sensor as the pressure (p1) side and the vacuum (p2) side. the pressure (p1) side is the side containing silicone gel which isolates the die from the environment. the motorola pres- sure sensor is designed to operate with positive differential pressure applied, p1 > p2. the pressure (p1) side may be identified by using the table below: part number case type pressure (p1) side identifier mpx53d 344 stainless steel cap mpx53dp 344c side with port marking mpx53gp 344b side with port attached mpxv53gc series 482a, 482c sides with port attached ordering information unibody package mpx53 series pressure sensors are available in differential and gauge configurations. devices are available with basic element package or with pressure port fittings which provide printed circuit board mounting ease and barbed hose pressure connections. mpx series device type options case type order number device marking basic element differential case 344 mpx53d mpx53d ported elements differential case 344c mpx53dp mpx53dp gauge case 344b mpx53gp mpx53gp ordering information e small outline package the mpxv53gc series pressure sensors are available with a pressure port, surface mount or dip leadforms, and two packing options. device order no. case no. packing options marking mpxv53gc6t1 482a tape & rail mpxv53g mpxv53gc6u 482a rails mpxv53g mpxv53gc7u 482c rails mpxv53g f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3118 motorola sensor device data www.motorola.com/semiconductors !! " ! !" ! ! the mpx5500 series piezoresistive transducer is a stateoftheart monolithic silicon pressure sensor designed for a wide range of applications, but particularly those employing a microcontroller or microprocessor with a/d inputs. this patented, single element transducer combines advanced micromachining techniques, thinfilm metalliza- tion, and bipolar processing to provide an accurate, high level analog output signal that is proportional to the applied pressure. features ? 2.5% maximum error over 0 to 85 c ? ideally suited for microprocessor or microcontrollerbased systems ? patented silicon shear stress strain gauge ? durable epoxy unibody element ? available in differential and gauge configurations v s sensing element v out gnd thin film temperature compensation and gain stage #1 gain stage #2 and ground reference shift circuitry pins 4, 5 and 6 are no connects figure 1. fully integrated pressure sensor schematic
semiconductor technical data integrated pressure sensor 0 to 500 kpa (0 to 72.5 psi) 0.2 to 4.7 volts output pin number note: pins 4, 5, and 6 are internal device connections. do not connect to external circuitry or ground. pin 1 is noted by the notch in the lead. mpx5500d case 867 mpx5500dp case 867c 1 2 3 v out gnd v s 4 5 6 n/c n/c n/c rev 5 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

3119 motorola sensor device data www.motorola.com/semiconductors maximum ratings (1) parametrics symbol value unit maximum pressure (2) (p2 1 atmosphere) p1 max 2000 kpa storage temperature t stg 40 to +125 c operating temperature t a 40 to +125 c notes: 1. maximum ratings apply to case 867 only. extended exposure at the specified limits may cause permanent damage or degradation to the device. 2. this sensor is designed for applications where p1 is always greater than, or equal to p2. p2 maximum is 500 kpa. operating characteristics (v s = 5.0 vdc, t a = 25 c unless otherwise noted, p1 > p2. decoupling circuit shown in figure 4 required to meet electrical specifications.) characteristic symbol min typ max unit pressure range (1) p op 0 e 500 kpa supply voltage (2) v s 4.75 5.0 5.25 vdc supply current i o e 7.0 10.0 madc zero pressure offset (3) (0 to 85 c) v off 0.088 0.20 0.313 vdc full scale output (4) (0 to 85 c) v fso 4.587 4.70 4.813 vdc full scale span (5) (0 to 85 c) v fss e 4.50 e vdc accuracy (6) e e e 2.5 %v fss sensitivity v/p e 9.0 e mv/kpa response time (7) t r e 1.0 e ms output source current at full scale output i o + e 0.1 e madc warmup time (8) e e 20 e ms notes: 1. 1.0kpa (kilopascal) equals 0.145 psi. 2. device is ratiometric within this specified excitation range. 3. offset (v off ) is defined as the output voltage at the minimum rated pressure. 4. full scale output (v fso ) is defined as the output voltage at full rated pressure. 5. full scale span (v fss ) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 6. accuracy (error budget) consists of the following: ? linearity: output deviation from a straight line relationship with pressure over the specified pressure range. ? temperature hysteresis: output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. ? pressure hysteresis: output deviation at any pressure within the specified range, when this pressure is cycled to and from minimum or maximum rated pressure at 25 c. ? tcspan: output deviation over the temperature range of 0 to 85 c, relative to 25 c. ? tcoffset: output deviation with minimum pressure applied, over the temperature range of 0 to 85 c, relative to 25 c. ? variation from nominal: the variation from nominal values, for offset or full scale span, as a percent of v fss at 25 c. 7. response time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when s ubjected to a specified step change in pressure. 8. warmup time is defined as the time required for the device to meet the specified output voltage after the pressure has been stabilized. mechanical characteristics characteristics typ unit weight, basic element (case 867) 4.0 grams f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

3120 motorola sensor device data www.motorola.com/semiconductors figure 3 illustrates the differential/gauge basic chip carrier (case 867). a fluorosilicone gel isolates the die surface and wire bonds from the environment, while allowing the pres- sure signal to be transmitted to the sensor diaphragm. (for use of the mpx5500d in a high pressure, cyclic application, consult the factory.) the mpx5500 series pressure sensor operating charac- teristics, and internal reliability and qualification tests are based on use of dry air as the pressure media. media, other than dry air, may have adverse effects on sensor perfor- mance and longterm reliability. contact the factory for information regarding media compatibility in your application. figure 2 shows the sensor output signal relative to pres- sure input. typical, minimum, and maximum output curves are shown for operation over a temperature range of 0 to 85 c using the decoupling circuit shown in figure 4 . the output will saturate outside of the specified pressure range. figure 4 shows the recommended decoupling circuit for interfacing the output of the integrated sensor to the a/d in- put of a microprocessor or microcontroller. proper decoup- ling of the power supply is recommended. max figure 2. output versus pressure differential differential pressure (kpa) 5.0 4.0 3.0 2.0 0 550 350 150 0 output (v) 450 250 4.5 3.5 2.5 1.5 50 transfer function: v out = v s *(0.0018*p+0.04) error v s = 5.0 vdc temp = 0 to 85 c 1.0 0.5 500 300 100 400 200 min typical fluoro silicone die coat lead frame stainless steel metal cover rtv die bond die epoxy case wire bond figure 3. crosssectional diagram (not to scale) p1 p2 figure 4. recommended power supply decoupling and output filtering. for additional output filtering, please refer to application note an1646. 1.0 f ips 470 pf output vs 5 v 0.01 f gnd vout f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

3121 motorola sensor device data www.motorola.com/semiconductors pressure (p1)/vacuum (p2) side identification table motorola designates the two sides of the pressure sensor as the pressure (p1) side and the vacuum (p2) side. the pressure (p1) side is the side containing fluorosilicone gel which protects the die from the environment. the motorola mpx pressure sensor is designed to operate with positive dif- ferential pressure applied, p1 > p2. the pressure (p1) side may be identified by using the table below: part number case type pressure (p1) side identifier mpx5500d 867 stainless steel cap mpx5500dp 867c side with part marking ordering information mpx series device name options case type order number device marking basic element differential 867 mpx5500d mpx5500d ported elements differential dual ports 867c mpx5500dp mpx5500dp f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3122 motorola sensor device data www.motorola.com/semiconductors
" " !!# ! " "# !" " the mpx5700 series piezoresistive transducer is a stateoftheart monolithic silicon pressure sensor designed for a wide range of applications, but particularly those employing a microcontroller or microprocessor with a/d inputs. this patented, single element transducer combines advanced micromachining techniques, thinfilm metalliza- tion, and bipolar processing to provide an accurate, high level analog output signal that is proportional to the applied pressure. features ? 2.5% maximum error over 0 to 85 c ? ideally suited for microprocessor or microcontrollerbased systems ? available in absolute, differential and gauge configurations ? patented silicon shear stress strain gauge ? durable epoxy unibody element figure 1. fully integrated pressure sensor schematic v s sensing element v out gnd thin film temperature compensation and gain stage #1 gain stage #2 and ground reference shift circuitry pins 4, 5 and 6 are no connects semiconductor technical data
integrated pressure sensor 0 to 700 kpa (0 to 101.5 psi) 15 to 700 kpa (2.18 to 101.5 psi) 0.2 to 4.7 v output pin number note: pins 4, 5, and 6 are internal device connections. do not connect to external circuitry or ground. pin 1 is noted by the notch in the lead. mpx5700d case 867 mpx5700dp case 867c 1 2 3 v out gnd v s 4 5 6 n/c n/c n/c mpx5700as case 867e rev 5 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

3123 motorola sensor device data www.motorola.com/semiconductors maximum ratings (1) parametrics symbol value unit maximum pressure (2) (p2 1 atmosphere) p1 max 2800 kpa storage temperature t stg 40 to +125 c operating temperature t a 40 to +125 c notes: 1. maximum ratings apply to case 867 only. extended exposure at the specified limits may cause permanent damage or degradation to the device. 2. this sensor is designed for applications where p1 is always greater than, or equal to p2. p2 maximum is 500 kpa. operating characteristics (v s = 5.0 vdc, t a = 25 c unless otherwise noted, p1 > p2. decoupling circuit shown in figure 4 required to meet electrical specifications.) characteristic symbol min typ max unit pressure range (1) gauge, differential: mpx5700d absolute: mpx5700a p op 0 15 e 700 700 kpa supply voltage (2) v s 4.75 5.0 5.25 vdc supply current i o 7.0 10 madc zero pressure offset (3) gauge, differential: (0 to 85 c) absolute (0 to 85 c) v off 0.088 0.184 0.2 0.313 0.409 vdc full scale output (4) (0 to 85 c) v fso 4.587 4.7 4.813 vdc full scale span (5) (0 to 85 c) v fss e 4.5 e vdc accuracy (6) (0 to 85 c) e e e 2.5 %v fss sensitivity v/p e 6.4 e mv/kpa response time (7) t r e 1.0 e ms output source current at full scale output i o+ e 0.1 e madc warmup time (8) e e 20 e ms notes: 1. 1.0 kpa (kilopascal) equals 0.145 psi. 2. device is ratiometric within this specified excitation range. 3. offset (v off ) is defined as the output voltage at the minimum rated pressure. 4. full scale output (v fso ) is defined as the output voltage at the maximum or full rated pressure. 5. full scale span (v fss ) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 6. accuracy (error budget) consists of the following: ? linearity: output deviation from a straight line relationship with pressure over the specified pressure range. ? temperature hysteresis: output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. ? pressure hysteresis: output deviation at any pressure within the specified range, when this pressure is cycled to and from the minimum or maximum rated pressure, at 25 c. ? tcspan: output deviation over the temperature range of 0 to 85 c, relative to 25 c. ? tcoffset: output deviation with minimum rated pressure applied, over the temperature range of 0 to 85 c, relative to 25 c. ? variation from nominal: the variation from nominal values, for offset or full scale span, as a percent of v fss , at 25 c. 7. response time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when s ubjected to a specified step change in pressure. 8. warmup time is defined as the time required for the device to meet the specified output voltage after the pressure has been stabilized. mechanical characteristics characteristics typ unit weight, basic element (case 867) 4.0 grams f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

3124 motorola sensor device data www.motorola.com/semiconductors onchip temperature compensation, calibration and signal conditioning figure 3 illustrates the differential/gauge basic chip car- rier (case 867). a fluorosilicone gel isolates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the sensor diaphragm. (for use of the mpx5700d in a high pressure, cyclic ap- plication, consult the factory.) the mpx5700 series pressure sensor operating character- istics, and internal reliability and qualification tests are based on use of dry air as the pressure media. media, other than dry air, may have adverse effects on sensor performance and longterm reliability. contact the factory for information regarding media compatibility in your application. figure 2 shows the sensor output signal relative to pres- sure input. typical, minimum, and maximum output curves are shown for operation over a temperature range of 0 to 85 c using the decoupling circuit shown in figure 4. the output will saturate outside of the specified pressure range. figure 4 shows the recommended decoupling circuit for interfacing the output of the integrated sensor to the a/d in- put of a microprocessor or microcontroller. proper decoup- ling of the power supply is recommended. differential pressure (kpa) figure 2. output versus pressure differential 5.0 4.0 3.0 2.0 0 700 300 0 500 4.5 3.5 2.5 1.5 100 1.0 0.5 600 200 800 400 typical output (v) transfer function: v out = v s *(0.0012858*p+0.04) error v s = 5.0 vdc temp = 0 to 85 c max min fluoro silicone die coat lead frame stainless steel metal cover rtv die bond die epoxy case wire bond figure 3. crosssectional diagram (not to scale) p1 p2 figure 4. recommended power supply decoupling and output filtering. for additional output filtering, please refer to application note an1646. 1.0 f ips 470 pf output vs 5 v 0.01 f gnd vout f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

3125 motorola sensor device data www.motorola.com/semiconductors pressure (p1)/vacuum (p2) side identification table motorola designates the two sides of the pressure sensor as the pressure (p1) side and the vacuum (p2) side. the pressure (p1) side is the side containing fluoro silicone gel which protects the die from harsh media. the motorola mpx pressure sensor is designed to operate with positive differen- tial pressure applied, p1 > p2. the pressure (p1) side may be identified by using the table below: part number case type pressure (p1) side identifier mpx5700d, mpx5700a 867 c stainless steel cap mpx5700dp 867c side with part marking mpx5700gp, mpx5700ap 867b side with port attached mpx5700gs, mpx5700as 867e side with port attached ordering information mpx series device type options case type order number device marking basic element differential 867 c mpx5700d mpx5700d absolute 867 c mpx5700a mpx5700a ported elements differential dual ports 867c mpx5700dp mpx5700dp gauge 867b mpx5700gp mpx5700gp gauge, axial 867e mpx5700gs mpx5700d absolute 867b mpx5700ap mpx5700ap absolute, axial 867e mpx5700as mpx5700a f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3126 motorola sensor device data www.motorola.com/semiconductors !! " ! !" ! ! the mpx5999d piezoresistive transducer is a stateoftheart pressure sensor designed for a wide range of applications, but particularly for those employing a microcontroller or microprocessor with a/d inputs. this patented, single element transducer combines advanced micromachining techniques, thinfilm metallization and bipolar semiconductor processing to provide an accurate, high level analog output signal that is proportional to applied pressure. figure 1 shows a block diagram of the internal circuitry integrated on the standalone sensing chip. features ? temperature compensated over 0 to 85 c ? ideally suited for microprocessor or microcontrollerbased systems ? patented silicon shear stress strain gauge ? durable epoxy unibody element figure 1. fully integrated pressure sensor schematic v s sensing element v out gnd thin film temperature compensation and gain stage #1 gain stage #2 and ground reference shift circuitry pins 4, 5 and 6 are no connects
semiconductor technical data integrated pressure sensor 0 to 1000 kpa (0 to 150 psi) 0.2 to 4.7 v output pin number 1 2 3 v out gnd v s 4 5 6 n/c n/c n/c mpx5999d case 867 note: pins 4, 5, and 6 are internal device connections. do not connect to external circuitry or ground. pin 1 is noted by the notch in the lead. rev 4 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3127 motorola sensor device data www.motorola.com/semiconductors maximum ratings (1) parametrics symbol value unit maximum pressure (2) (p1 > p2) p1 max 4000 kpa storage temperature t stg 40 to +125 c operating temperature t a 40 to +125 c notes: 1. extended exposure at the specified limits may cause permanent damage or degradation to the device. 2. this sensor is designed for applications where p1 is always greater than, or equal to p2. p2 maximum is 500 kpa. operating characteristics (v s = 5.0 vdc, t a = 25 c unless otherwise noted, p1 > p2. decoupling circuit shown in figure 4 required to meet electrical specifications.) characteristic symbol min typ max unit pressure range (1) p op 0 e 1000 kpa supply voltage (2) v s 4.75 5.0 5.25 vdc supply current i o e 7.0 10 madc zero pressure offset (3) (0 to 85 c) v off 0.088 0.2 0.313 vdc full scale output (4) (0 to 85 c) v fso 4.587 4.7 4.813 vdc full scale span (5) (0 to 85 c) v fss e 4.5 e vdc sensitivity v/p e 4.5 e mv/kpa accuracy (6) (0 to 85 c) e e e 2.5 %v fss response time (7) t r e 1.0 e ms output source current at full scale output i o+ e 0.1 e ma warmup time (8) e e 20 e ms notes: 1. 1.0 kpa (kilopascal) equals 0.145 psi. 2. device is ratiometric within this specified excitation range. 3. offset (v off ) is defined as the output voltage at the minimum rated pressure. 4. full scale output (v fso ) is defined as the output voltage at the maximum or full rated pressure. 5. full scale span (v fss ) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 6. accuracy (error budget) consists of the following: ? linearity: output deviation from a straight line relationship with pressure over the specified pressure range. ? temperature hysteresis: output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. ? pressure hysteresis: output deviation at any pressure within the specified range, when this pressure is cycled to and from the minimum or maximum rated pressure, at 25 c. ? tcspan: output deviation over the temperature range of 0 to 85 c, relative to 25 c. ? tcoffset: output deviation with minimum rated pressure applied, over the temperature range of 0 to 85 c, relative to 25 c. ? variation from nominal: the variation from nominal values, for offset or full scale span, as a percent of v fss , at 25 c. 7. response time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when s ubjected to a specified step change in pressure. 8. warmup time is defined as the time required for the device to meet the specified output voltage after the pressure has been stabilized. mechanical characteristics characteristics typ unit weight, basic element (case 867) 4.0 grams f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3128 motorola sensor device data www.motorola.com/semiconductors onchip temperature compensation, calibration and signal conditioning figure 2 shows the sensor output signal relative to pres- sure input. typical, minimum, and maximum output curves are shown for operation over a temperature range of 0 to 85 c using the decoupling circuit shown in figure 4. the output will saturate outside of the specified pressure range. the performance over temperature is achieved by integrat- ing the shearstress strain gauge, temperature compensa- tion, calibration and signal conditioning circuitry onto a single monolithic chip. figure 3 illustrates the differential or gauge configuration in the basic chip carrier (case 867). a fluoro silicone gel isolates the die surface and wire bonds from harsh environments, while al- lowing the pressure signal to be transmitted to the silicon dia- phragm. the mpx5999d pressure sensor operating characteristics, and internal reliability and qualification tests are based on use of dry air as the pressure media. media other than dry air may have adverse effects on sensor performance and longterm reliability. contact the factory for information regarding media compatibility in your application. figure 4 shows the recommended decoupling circuit for interfacing the output of the integrated sensor to the a/d in- put of a microprocessor or microcontroller. proper decoup- ling of the power supply is recommended. max figure 2. output versus pressure differential differential pressure (kpa) 5.0 4.0 3.0 2.0 0 1100 700 300 0 output (v) 900 500 4.5 3.5 2.5 1.5 100 transfer function: v out = v s *(0.000901*p+0.04) error v s = 5.0 vdc temp = 0 to 85 c 1.0 0.5 1000 600 200 800 400 min typical silicone die coat lead frame stainless steel metal cover rtv die bond die wire bond figure 3. crosssectional diagram (not to scale) thermoplastic case p1 p2 figure 4. recommended power supply decoupling and output filtering. for additional output filtering, please refer to application note an1646. 1.0 f ips 470 pf output vs 5 v 0.01 f gnd vout f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3129 motorola sensor device data www.motorola.com/semiconductors pressure (p1) / vacuum (p2) side identification table motorola designates the two sides of the pressure sensor as the pressure (p1) side and the vacuum (p2) side. the pressure (p1) side is the side containing fluoro silicone gel which protects the die from harsh media. the motorola mpx pressure sensor is designed to operate with positive differen- tial pressure applied, p1 > p2. the pressure (p1) side may be identified by using the table below: part number case type pressure (p1) side identifier mpx5999d 867 stainless steel cap ordering information the mpx5999d pressure sensor is available as an element only. mpx series device type options case type order number device marking basic element differential 867 mpx5999d mpx5999d f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3130 motorola sensor device data www.motorola.com/semiconductors
!"$%" %"& $"$ "##%" # " " #%" # %$ "##%" ! $ !"$%" !#$ "$ motorola's mpxa6115a/mpxh6115a series sensor integrates onc hip, bipolar op amp circuitry and thin film resistor networks to provide a high output signal and temperature compensation. the small form factor and high reliability of onchip integration make the motorola pressure sensor a logical and economical choice for the system designer. the mpxa6115a/mpxh6115a series piezoresistive transducer is a stateoftheart, monolithic, signal conditioned, silicon pressure sensor. this sensor combines advanced micromachining tec hniques, thin film metallization, and bipolar semiconductor processing to provide an accurate, high level analog output signal that is proportional to applied pressure. figure 1 shows a block diagram of the internal circuitry integrated on a pressure sensor chip. features ? improved accuracy at high temperature ? available in small and super small outline packages ? 1.5% maximum error over 0 to 85 c ? ideally suited for microprocessor or microcontrollerbased systems ? temperature compensated from 40 to +125 c ? durable thermoplastic (pps) surface mount package application examples ? aviation altimeters ? industrial controls ? engine control/manifold absolute pressure (map) ? weather station and weather reporting device barometers figure 1. fully integrated pressure sensor schematic v s sensing element v out gnd thin film temperature compensation and gain stage #1 gain stage #2 and ground reference shift circuitry pins 1, 5, 6, 7 and 8 are no connects semiconductor technical data
integrated pressure sensor 15 to 115 kpa (2.2 to 16.7 psi) 0.2 to 4.8 volts output pin number note: pins 1, 5, 6, 7, and 8 are internal device connections. do not connect to external circuitry or ground. pin 1 is denoted by the notch in the lead. 1 2 3 n/c v s gnd 5 6 7 n/c n/c n/c mpxa6115a6u case 482 mpxa6115ac6u case 482a 4v out 8 n/c small outline package pin number note: pins 1, 5, 6, 7, and 8 are internal device connections. do not connect to external circuitry or ground. pin 1 is denoted by the chamfered corner of the package. 1 2 3 n/c v s gnd 5 6 7 n/c n/c n/c mpxh6115a6u case 1317 mpxh6115ac6u case 1317a 4v out 8 n/c super small outline package rev 1 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

3131 motorola sensor device data www.motorola.com/semiconductors maximum ratings (1) parametrics symbol value units maximum pressure (p1 p2) p max 400 kpa storage temperature t stg 40 to +125 c operating temperature t a 40 to +125 c output source current @ full scale output (2) i o + 0.5 madc output sink current @ minimum pressure offset (2) i o 0.5 madc notes: 1. exposure beyond the specified limits may cause permanent damage or degradation to the device. 2. maximum output current is controlled by effective impedance from v out to gnd or v out to v s in the application circuit. operating characteristics (v s = 5.0 vdc, t a = 25 c unless otherwise noted, p1 p2.) characteristic symbol min typ max unit pressure range p op 15 e 115 kpa supply voltage (1) v s 4.75 5.0 5.25 vdc supply current i o e 6.0 10 madc minimum pressure offset (2) (0 to 85 c) @ v s = 5.0 volts v off 0.133 0.200 0.268 vdc full scale output (3) (0 to 85 c) @ v s = 5.0 volts v fso 4.633 4.700 4.768 vdc full scale span (4) (0 to 85 c) @ v s = 5.0 volts v fss 4.433 4.500 4.568 vdc accuracy (5) (0 to 85 c) e e e 1.5 %v fss sensitivity v/p e 45.9 e mv/kpa response time (6) t r e 1.0 e ms warmup time (7) e e 20 e ms offset stability (8) e e 0.25 e %v fss notes: 1. device is ratiometric within this specified excitation range. 2. offset (v off ) is defined as the output voltage at the minimum rated pressure. 3. full scale output (v fso ) is defined as the output voltage at the maximum or full rated pressure. 4. full scale span (v fss ) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 5. accuracy is the deviation in actual output from nominal output over the entire pressure range and temperature range as a perc ent of span at 25 c due to all sources of error including the following: ? linearity: output deviation from a straight line relationship with pressure over the specified pressure range. ? temperature hysteresis: output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. ? pressure hysteresis: output deviation at any pressure within the specified range, when this pressure is cycled to and from minimum or maximum rated pressure at 25 c. ? tcspan: output deviation over the temperature range of 0 to 85 c, relative to 25 c. ? tcoffset: output deviation with minimum pressure applied, over the temperature range of 0 to 85 c, relative to 25 c. 6. response time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when s ubjected to a specified step change in pressure. 7. warmup time is defined as the time required for the product to meet the specified output voltage after the pressure has been stabilized. 8. offset stability is the product's output deviation when subjected to 1000 cycles of pulsed pressure, temperature cycling with bias test. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

3132 motorola sensor device data www.motorola.com/semiconductors figure 2. cross sectional diagram ssop (not to scale) figure 3. typical application circuit (output source current operation) wire bond stainless steel cap thermoplastic case die bond sealed vacuum reference di e p1 fluoro silicone gel die coat lead frame absolute element v s pin 2 5.0 v gnd pin 3 v out pin 4 mpxa6115a to adc 100 nf 51 k 47 pf mpxh6115a figure 2 illustrates the absolute sensing chip in the basic super small outline chip carrier (case 1317). figure 3 shows a typical application circuit (output source current operation). output (volts) 5.0 4.5 4.0 3.5 3.0 pressure (ref: to sealed vacuum) in kpa typ max min 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 2.5 2.0 1.5 1.0 0.5 0 110 figure 4. output versus absolute pressure transfer function: v out = v s * (.009*p.095) error v s = 5.0 vdc temp = 0 to 85 c 115 120 figure 4 shows the sensor output signal relative to pres- sure input. typical minimum and maximum output curves are shown for operation over 0 to 85 c temperature range. the output will saturate outside of the rated pressure range. a fluorosilicone gel isolates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the s ilicon diaphragm. the mpxa6115a/mpxh6115a series pressure sensor operating characteristics, internal reliability and qualification tests are based on use of dry air as the pressure media. media other than dry air may have adverse effects on sensor perfor- mance and longterm reliability. contact the factory for information regarding media compatibility in your application. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

3133 motorola sensor device data www.motorola.com/semiconductors transfer function (mpxa6115a/mpxh6115a) nominal transfer value: v out = v s x (0.009 x p 0.095) (pressure error x temp. factor x 0.009 x v s ) v s = 5.0 0.25 vdc temperature error band mpxa6115a/mpxh6115a series break points temp multiplier 40 3 0 to 85 1 125 1.75 temperature in c 4.0 3.0 2.0 0.0 1.0 40 20 0 20 40 60 140 120 100 80 temperature error factor note: the temperature multiplier is a linear response from 0 c to 40 c and from 85 c to 125 c pressure error band error limits for pressure 3.0 2.0 1.0 1.0 2.0 3.0 0.0 20 pressure (in kpa) pressure error (kpa) pressure error (max) 15 to 115 (kpa) 1.5 (kpa) 40 60 80 100 120 ordering information e small outline package device type options case no. mpx series order no. packing options marking basic element absolute, element only 482 mpxa6115a6u rails mpxa6115a absolute, element only 482 mpxa6115a6t1 tape and reel mpxa6115a ported element absolute, axial port 482a mpxa6115ac6u rails mpxa6115a absolute, axial port 482a mpxa6115ac6t1 tape and reel mpxa6115a ordering information e super small outline package device type options case no. mpx series order no. packing options marking basic element absolute, element only 1317 mpxh6115a6u rails mpxh6115a absolute, element only 1317 mpxh6115a6t1 tape and reel mpxh6115a ported element absolute, axial port 1317a mpxh6115ac6u rails mpxh6115a absolute, axial port 1317a mpxh6115ac6t1 tape and reel mpxh6115a f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

3134 motorola sensor device data www.motorola.com/semiconductors surface mounting information minimum recommended footprint for small and super small packages surface mount board layout is a critical portion of the total design. the footprint for the semiconductor package must be the correct size to ensure proper solder connection inter- face between the board and the package. with the correct pad geometry, the packages will selfalign when subjected to a solder reflow process. it is always recommended to fabri- cate boards with a solder mask layer to avoid bridging and/or shorting between solder pads, especially on tight tolerances and/or tight layouts. 0.660 16.76 0.060 typ 8x 1.52 0.100 typ 8x 2.54 0.100 typ 2.54 0.300 7.62 figure 5. sop footprint (case 482) inch mm figure 6. ssop footprint (case 1317 and 1317a) 0.027 typ 8x 0.69 0.053 typ 8x 1.35 inch mm 0.387 9.83 0.150 3.81 0.050 1.27 typ f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3135 motorola sensor device data www.motorola.com/semiconductors ##$$
$"$ "##%" # " " # %$ "##%" !!$ # ! $ !"$%" !#$ "$ the motorola mpxaz4100a series manifold absolute pressure (map) sensor for engine control is designed to sense absolute air pressure within the intake manifold. this measurement can be used to compute the amount of fuel required for each cylinder. the small form factor and high reliability of onchip integration makes the motorola map sensor a logical and economical choice for automotive system designers. the mpxaz4100a series piezoresistive transducer is a stateoftheart, monolithic, signal conditioned, silicon pressure sensor. this sensor combines advanced micromachining techniques, thin film metallization, and bipolar semiconductor processing to provide an accurate, high level analog output signal that is proportional to applied pressure. figure 1 shows a block diagram of the internal circuitry integrated on a pressure sensor chip. features ? resistant to high humidity and common automotive media ? 1.8% maximum error over 0 to 85 c ? specifically designed for intake manifold absolute pressure sensing in engine control systems ? ideally suited for microprocessor or microcontroller based systems ? temperature compensated over 40 c to +125 c ? durable thermoplastic (pps) surface mount package application examples ? manifold sensing for automotive systems ? also ideal for nonautomotive applications figure 1. fully integrated pressure sensor schematic v s sensing element v out gnd thin film temperature compensation and gain stage #1 gain stage #2 and ground reference shift circuitry pins 1, 5, 6, 7 and 8 are no connects for small outline package device semiconductor technical data 5 6 7 8 gnd v out 4 1 2 3
integrated pressure sensor 20 to 105 kpa (2.9 to 15.2 psi) 0.3 to 4.9 v output pin number n/c v s n/c n/c n/c n/c note: pins 1, 5, 6, 7, and 8 are not device connections. do not connect to external circuitry or ground. pin 1 is noted by the notch in the lead. mpxaz4100ac6u case 482a small outline package mpxaz4100a6u case 482 rev 0 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

3136 motorola sensor device data www.motorola.com/semiconductors maximum ratings (note) parametric symbol value unit maximum pressure (p1 > p2) p max 400 kpa storage temperature t stg 40 to +125 c operating temperature t a 40 to +125 c note: exposure beyond the specified limits may cause permanent damage or degradation to the device. operating characteristics (v s = 5.1 vdc, t a = 25 c unless otherwise noted, p1 > p2. decoupling circuit shown in figure 3 required to meet electrical specifications.) characteristic symbol min typ max unit pressure range (1) p op 20 e 105 kpa supply voltage (2) v s 4.85 5.1 5.35 vdc supply current i o e 7.0 10 madc minimum pressure offset (3) (0 to 85 c) @ v s = 5.1 volts v off 0.225 0.306 0.388 vdc full scale output (4) (0 to 85 c) @ v s = 5.1 volts v fso 4.870 4.951 5.032 vdc full scale span (5) (0 to 85 c) @ v s = 5.1 volts v fss e 4.59 e vdc accuracy (6) (0 to 85 c) e e e 1.8 %v fss sensitivity v/p e 54 e mv/kpa response time (7) t r e 1.0 e ms output source current at full scale output i o+ e 0.1 e madc warmup time (8) e e 20 e ms offset stability (9) e e 0.5 e %v fss notes: 1. 1.0 kpa (kilopascal) equals 0.145 psi. 2. device is ratiometric within this specified excitation range. 3. offset (v off ) is defined as the output voltage at the minimum rated pressure. 4. full scale output (v fso ) is defined as the output voltage at the maximum or full rated pressure. 5. full scale span (v fss ) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 6. accuracy (error budget) consists of the following: ? linearity: output deviation from a straight line relationship with pressure over the specified pressure range. ? temperature hysteresis: output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. ? pressure hysteresis: output deviation at any pressure within the specified range, when this pressure is cycled to and from the minimum or maximum rated pressure, at 25 c. ? tcspan: output deviation over the temperature range of 0 to 85 c, relative to 25 c. ? tcoffset: output deviation with minimum rated pressure applied, over the temperature range of 0 to 85 c, relative to 25 c. ? variation from nominal: the variation from nominal values, for offset or full scale span, as a percent of v fss , at 25 c. 7. response time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when s ubjected to a specified step change in pressure. 8. warmup time is defined as the time required for the product to meet the specified output voltage after the pressure has been stabilized. 9. offset stability is the product's output deviation when subjected to 1000 hours of pulsed pressure, temperature cycling with bias test. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

3137 motorola sensor device data www.motorola.com/semiconductors figure 2. cross sectional diagram sop (not to scale) wire bond stainless steel cap thermoplastic case die bond sealed vacuum reference die p1 fluoro silicone gel die coat lead frame absolute element figure 2 illustrates an absolute sensing chip in the basic chip carrier (case 482). output (volts) 5.0 4.5 4.0 3.5 3.0 pressure (ref: to sealed vacuum) in kpa typ max min 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 2.5 2.0 1.5 1.0 0.5 0 110 temp = 0 to 85 c 20 kpa to 105 kpa mpxaz4100a transfer function: v out = v s * (.01059*p.152) error v s = 5.1 vdc figure 3. recommended power supply decoupling and output filtering. for additional output filtering, please refer to application note an1646. figure 4. output versus absolute pressure 1.0 f ips 470 pf output vs 5 v 0.01 f gnd vout figure 4 shows the sensor output signal relative to pres- sure input. typical, minimum, and maximum output curves are shown for operation over a temperature range of 0 to 85 c using the decoupling circuit shown in figure 3. the output will saturate outside of the specified pressure range. a gel die coat isolates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the sensor diaphragm. the gel die coat and durable polymer package provide a media resis- tant barrier that allows the sensor to operate reliably in high humidity conditions as well as environments contain- ing common automotive media. contact the factory for more information regarding media compatibility in your specific application. figure 3 shows the recommended decoupling circuit for in- terfacing the output of the integrated sensor to the a/d input of a microprocessor or microcontroller. proper decoupling of the power supply is recommended. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

3138 motorola sensor device data www.motorola.com/semiconductors transfer function (mpxaz4100a) nominal transfer value: v out = v s (p x 0.01059 0.1518) +/ (pressure error x temp. factor x 0.01059 x v s ) v s = 5.1 v 0.25 vdc temperature error band mpxaz4100a series temp multiplier 40 3 0 to 85 1 +125 3 temperature in c 4.0 3.0 2.0 0.0 1.0 40 20 0 20 40 60 140 120 100 80 temperature error factor note: the temperature multiplier is a linear response from 0 c to 40 c and from 85 c to 125 c. pressure error band error limits for pressure 3.0 2.0 1.0 1.0 2.0 3.0 0.0 20 40 60 80 100 120 pressure (in kpa) pressure error (kpa) pressure error (max) 20 to 105 (kpa) 1.5 (kpa) ordering information e small outline package device type options case no. mpx series order no. packing options marking basic element absolute, element only 482 mpxaz4100a6u rails mpxaz4100a absolute, element only 482 mpxaz4100a6t1 tape and reel mpxaz4100a ported element absolute, axial port 482a mpxaz4100ac6u rails mpxaz4100a absolute, axial port 482a mpxaz4100ac6t1 tape and reel mpxaz4100a f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

3139 motorola sensor device data www.motorola.com/semiconductors information for using the small outline package (case 482) minimum recommended footprint for surface mounted applications surface mount board layout is a critical portion of the total design. the footprint for the surface mount packages must be the correct size to ensure proper solder connection inter- face between the board and the package. with the correct fottprint, the packages will self align when subjected to a solder reflow process. it is always recommended to design boards with a solder mask layer to avoid bridging and short- ing between solder pads. 0.660 16.76 0.060 typ 8x 1.52 0.100 typ 8x 2.54 0.100 typ 8x 2.54 0.300 7.62 figure 5. sop footprint (case 482) inch mm scale 2:1 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3140 motorola sensor device data www.motorola.com/semiconductors $$% % %#% ! #$$&# $!# !# ! $!&% #$$&# %%# !# #!%# ""%! $ " ! %! "#%&# !" $% #% motorola's mpxaz4115a series sensor integrates onc hip, bipolar op amp circuitry and thin film resistor networks to provide a high output signal and temperature compensation. the small form factor and high reliability of onchip integration make the motorola pressure sensor a logical and economical choice for the system designer. the mpxaz4115a series piezoresistive transducer is a stateoftheart, monolithic, signal conditioned, silicon pressure sensor. this sensor combines advanced micromachining tec hniques, thin film metallization, and bipolar semiconductor processing to provide an accurate, high level analog output signal that is proportional to applied pressure. figure 1 shows a block diagram of the internal circuitry integrated on a pressure sensor chip. features ? resistant to high humidity and common automotive media ? 1.5% maximum error over 0 to 85 c ? ideally suited for microprocessor or microcontroller based systems ? temperature compensated from 40 to +125 c ? durable thermoplastic (pps) surface mount package application examples ? aviation altimeters ? industrial controls ? engine control ? weather stations and weather reporting devices figure 1. fully integrated pressure sensor schematic v s sensing element v out gnd thin film temperature compensation and gain stage #1 gain stage #2 and ground reference shift circuitry pins 1, 5, 6, 7 and 8 are no connects for small outline package device semiconductor technical data 5 6 7 8 gnd v out 4 1 2 3

integrated pressure sensor 15 to 115 kpa (2.2 to 16.7 psi) 0.2 to 4.8 v output pin number n/c v s n/c n/c n/c n/c note: pins 1, 5, 6, 7, and 8 are not device connections. do not connect to external circuitry or ground. pin 1 is noted by the notch in the lead. mpxaz4115ac6u case 482a small outline package mpxaz4115a6u case 482 rev 0 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

3141 motorola sensor device data www.motorola.com/semiconductors maximum ratings (note) parametrics symbol value units maximum pressure (p1 p2) p max 400 kpa storage temperature t stg 40 to +125 c operating temperature t a 40 to +125 c note: exposure beyond the specified limits may cause permanent damage or degradation to the device. operating characteristics (v s = 5.1 vdc, t a = 25 c unless otherwise noted, p1 p2. decoupling circuit shown in figure 3 required to meet electrical specifications.) characteristic symbol min typ max unit pressure range p op 15 e 115 kpa supply voltage (1) v s 4.85 5.1 5.35 vdc supply current i o e 7.0 10 madc minimum pressure offset (2) (0 to 85 c) @ v s = 5.1 volts v off 0.135 0.204 0.273 vdc full scale output (3) (0 to 85 c) @ v s = 5.1 volts v fso 4.725 4.794 4.863 vdc full scale span (4) (0 to 85 c) @ v s = 5.1 volts v fss 4.521 4.590 4.659 vdc accuracy (5) (0 to 85 c) e e e 1.5 %v fss sensitivity v/p e 45.9 e mv/kpa response time (6) t r e 1.0 e ms output source current at full scale output i o+ e 0.1 e madc warmup time (7) e e 20 e ms offset stability (8) e e 0.5 e %v fss notes: 1. device is ratiometric within this specified excitation range. 2. offset (v off ) is defined as the output voltage at the minimum rated pressure. 3. full scale output (v fso ) is defined as the output voltage at the maximum or full rated pressure. 4. full scale span (v fss ) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 5. accuracy is the deviation in actual output from nominal output over the entire pressure range and temperature range as a perc ent of span at 25 c due to all sources of error including the following: ? linearity: output deviation from a straight line relationship with pressure over the specified pressure range. ? temperature hysteresis: output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. ? pressure hysteresis: output deviation at any pressure within the specified range, when this pressure is cycled to and from minimum or maximum rated pressure at 25 c. ? tcspan: output deviation over the temperature range of 0 to 85 c, relative to 25 c. ? tcoffset: output deviation with minimum pressure applied, over the temperature range of 0 to 85 c, relative to 25 c. 6. response time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when s ubjected to a specified step change in pressure. 7. warmup time is defined as the time required for the product to meet the specified output voltage after the pressure has been stabilized. 8. offset stability is the product's output deviation when subjected to 1000 cycles of pulsed pressure, temperature cycling with bias test. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

3142 motorola sensor device data www.motorola.com/semiconductors wire bond stainless steel cap thermoplastic case die bond sealed vacuum reference die p1 fluoro silicone gel die coat lead frame absolute element figure 2. cross sectional diagram sop (not to scale) 1.0 f ips 470 pf output vs 5 v 0.01 f gnd vout figure 3. recommended power supply decoupling and output filtering. for additional output filtering, please refer to application note an1646. figure 2 illustrates the absolute sensing chip in the basic chip carrier (case 482). figure 3 shows the recommended decoupling circuit for interfacing the output of the integrated sensor to the a/d in- put of a microprocessor or microcontroller. proper decoup- ling of the power supply is recommended. output (volts) 5.0 4.5 4.0 3.5 3.0 pressure (ref: to sealed vacuum) in kpa typ max min 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 2.5 2.0 1.5 1.0 0.5 0 110 figure 4. output versus absolute pressure transfer function: v out = v s * (.009*p.095) error v s = 5.1 vdc temp = 0 to 85 c 115 120 figure 4 shows the sensor output signal relative to pres- sure input. typical minimum and maximum output curves are shown for operation over a temperature range of 0 to 85 c using the decoupling circuit shown in figure 3. the output will saturate outside of the specified pressure range. a gel die coat isolates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the sensor diaphragm. the gel die coat and durable polymer package provide a media resis- tant barrier that allows the sensor to operate reliably in high humidity conditions as well as environments contain- ing common automotive media. contact the factory for more information regarding media compatibility in your specific application. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

3143 motorola sensor device data www.motorola.com/semiconductors transfer function (mpxaz4115a) nominal transfer value: v out = v s x (0.009 x p 0.095) (pressure error x temp. factor x 0.009 x v s ) v s = 5.1 0.25 vdc temperature error band mpxaz4115a series break points temp multiplier 40 3 0 to 85 1 125 3 temperature in c 4.0 3.0 2.0 0.0 1.0 40 20 0 20 40 60 140 120 100 80 temperature error factor note: the temperature multiplier is a linear response from 0 c to 40 c and from 85 c to 125 c pressure error band error limits for pressure 3.0 2.0 1.0 1.0 2.0 3.0 0.0 20 pressure (in kpa) pressure error (kpa) pressure error (max) 15 to 115 (kpa) 1.5 (kpa) 40 60 80 100 120 ordering information e small outline package device type options case no. mpx series order no. packing options marking basic element absolute, element only 482 mpxaz4115a6u rails mpxaz4115a absolute, element only 482 mpxaz4115a6t1 tape and reel mpxaz4115a ported element absolute, axial port 482a mpxaz4115ac6u rails mpxaz4115a absolute, axial port 482a mpxaz4115ac6t1 tape and reel mpxaz4115a f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

3144 motorola sensor device data www.motorola.com/semiconductors information for using the small outline package (case 482) minimum recommended footprint for surface mounted applications surface mount board layout is a critical portion of the total design. the footprint for the surface mount packages must be the correct size to ensure proper solder connection inter- face between the board and the package. with the correct fottprint, the packages will selfalign when subjected to a solder reflow process. it is always recommended to design boards with a solder mask layer to avoid bridging and short- ing between solder pads. 0.660 16.76 0.060 typ 8x 1.52 0.100 typ 8x 2.54 0.100 typ 8x 2.54 0.300 7.62 figure 5. sop footprint (case 482) inch mm scale 2:1 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3145 motorola sensor device data www.motorola.com/semiconductors $$% %
"#%&# &#' %#% ! #$$&# $!# !# $&# $!&% #$$&# " ! %! "#%&# !" $% #% motorola's mpxaz6115a series sensor integrates onc hip, bipolar op amp circuitry and thin film resistor networks to provide a high output signal and temperature compensation. the small form factor and high reliability of onchip integration make the motorola pressure sensor a logical and economical choice for the system designer. the mpxaz6115a series piezoresistive transducer is a stateoftheart, monolithic, signal conditioned, silicon pressure sensor. this sensor combines advanced micromachining tec hniques, thin film metallization, and bipolar semiconductor processing to provide an accurate, high level analog output signal that is proportional to applied pressure. figure 1 shows a block diagram of the internal circuitry integrated on a pressure sensor chip. features ? resistant to high humidity and common automotive media ? improved accuracy at high temperature ? 1.5% maximum error over 0 to 85 c ? ideally suited for microprocessor or microcontrollerbased systems ? temperature compensated from 40 to +125 c ? durable thermoplastic (pps) surface mount package application examples ? aviation altimeters ? industrial controls ? engine control/manifold absolute pressure (map) ? weather station and weather reporting devices figure 1. fully integrated pressure sensor schematic v s sensing element v out gnd thin film temperature compensation and gain stage #1 gain stage #2 and ground reference shift circuitry pins 1, 5, 6, 7 and 8 are no connects semiconductor technical data 5 6 7 8 n/c v s gnd v out n/c n/c n/c integrated pressure sensor 15 to 115 kpa (2.2 to 16.7 psi) 0.2 to 4.8 volts output pin number note: pins 1, 5, 6, 7, and 8 are internal device connections. do not connect to external circuitry or ground. pin 1 is denoted by the notch in the lead. 1 2 3 mpxaz6115a6u case 482 mpxaz6115ac6u case 482a 4 n/c small outline package rev 0 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

3146 motorola sensor device data www.motorola.com/semiconductors maximum ratings (1) parametrics symbol value units maximum pressure (p1 p2) p max 400 kpa storage temperature t stg 40 to +125 c operating temperature t a 40 to +125 c output source current @ full scale output (2) i o + 0.5 madc output sink current @ minimum pressure offset (2) i o 0.5 madc notes: 1. exposure beyond the specified limits may cause permanent damage or degradation to the device. 2. maximum output current is controlled by effective impedance from v out to gnd or v out to v s in the application circuit. operating characteristics (v s = 5.0 vdc, t a = 25 c unless otherwise noted, p1 p2.) characteristic symbol min typ max unit pressure range p op 15 e 115 kpa supply voltage (1) v s 4.75 5.0 5.25 vdc supply current i o e 6.0 10 madc minimum pressure offset (2) (0 to 85 c) @ v s = 5.0 volts v off 0.133 0.200 0.268 vdc full scale output (3) (0 to 85 c) @ v s = 5.0 volts v fso 4.633 4.700 4.768 vdc full scale span (4) (0 to 85 c) @ v s = 5.0 volts v fss 4.433 4.500 4.568 vdc accuracy (5) (0 to 85 c) e e e 1.5 %v fss sensitivity v/p e 45.9 e mv/kpa response time (6) t r e 1.0 e ms warmup time (7) e e 20 e ms offset stability (8) e e 0.25 e %v fss notes: 1. device is ratiometric within this specified excitation range. 2. offset (v off ) is defined as the output voltage at the minimum rated pressure. 3. full scale output (v fso ) is defined as the output voltage at the maximum or full rated pressure. 4. full scale span (v fss ) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 5. accuracy is the deviation in actual output from nominal output over the entire pressure range and temperature range as a perc ent of span at 25 c due to all sources of error including the following: ? linearity: output deviation from a straight line relationship with pressure over the specified pressure range. ? temperature hysteresis: output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. ? pressure hysteresis: output deviation at any pressure within the specified range, when this pressure is cycled to and from minimum or maximum rated pressure at 25 c. ? tcspan: output deviation over the temperature range of 0 to 85 c, relative to 25 c. ? tcoffset: output deviation with minimum pressure applied, over the temperature range of 0 to 85 c, relative to 25 c. 6. response time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when s ubjected to a specified step change in pressure. 7. warmup time is defined as the time required for the product to meet the specified output voltage after the pressure has been stabilized. 8. offset stability is the product's output deviation when subjected to 1000 cycles of pulsed pressure, temperature cycling with bias test. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

3147 motorola sensor device data www.motorola.com/semiconductors figure 2. cross sectional diagram sop (not to scale) figure 3. typical application circuit (output source current operation) wire bond stainless steel cap thermoplastic case die bond sealed vacuum reference die p1 fluoro silicone gel die coat lead frame absolute element v s pin 2 5.0 v gnd pin 3 v out pin 4 mpxaz6115a to adc 100 nf 51 k 47 pf figure 2 illustrates the absolute sensing chip in the basic small outline chip carrier (case 482). figure 3 shows a typical application circuit (output source current operation). output (volts) 5.0 4.5 4.0 3.5 3.0 pressure (ref: to sealed vacuum) in kpa typ max min 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 2.5 2.0 1.5 1.0 0.5 0 110 figure 4. output versus absolute pressure transfer function: v out = v s * (.009*p.095) error v s = 5.0 vdc temp = 0 to 85 c 115 120 figure 4 shows the sensor output signal relative to pres- sure input. typical minimum and maximum output curves are shown for operation over 0 to 85 c temperature range. the output will saturate outside of the rated pressure range. a gel die coat isolates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the sensor diaphragm. the gel die coat and durable polymer package provide a media resis- tant barrier that allows the sensor to operate reliably in high humidity conditions as well as environments contain- ing common automotive media. contact the factory for more information regarding media compatibility in your specific application. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

3148 motorola sensor device data www.motorola.com/semiconductors transfer function (mpxaz6115a) nominal transfer value: v out = v s x (0.009 x p 0.095) (pressure error x temp. factor x 0.009 x v s ) v s = 5.0 0.25 vdc temperature error band mpxaz6115a series break points temp multiplier 40 3 0 to 85 1 125 1.75 temperature in c 4.0 3.0 2.0 0.0 1.0 40 20 0 20 40 60 140 120 100 80 temperature error factor note: the temperature multiplier is a linear response from 0 c to 40 c and from 85 c to 125 c pressure error band error limits for pressure 3.0 2.0 1.0 1.0 2.0 3.0 0.0 20 pressure (in kpa) pressure error (kpa) pressure error (max) 15 to 115 (kpa) 1.5 (kpa) 40 60 80 100 120 ordering information e small outline package device type options case no. mpx series order no. packing options marking basic element absolute, element only 482 mpxaz6115a6u rails mpxaz6115a absolute, element only 482 mpxaz6115a6t1 tape and reel mpxaz6115a ported element absolute, axial port 482a mpxaz6115ac6u rails mpxaz6115a absolute, axial port 482a mpxaz6115ac6t1 tape and reel mpxaz6115a f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

3149 motorola sensor device data www.motorola.com/semiconductors surface mounting information minimum recommended footprint for small outline package surface mount board layout is a critical portion of the total design. the footprint for the semiconductor package must be the correct size to ensure proper solder connection inter- face between the board and the package. with the correct pad geometry, the packages will selfalign when subjected to a solder reflow process. it is always recommended to fabri- cate boards with a solder mask layer to avoid bridging and/or shorting between solder pads, especially on tight tolerances and/or tight layouts. 0.660 16.76 0.060 typ 8x 1.52 0.100 typ 8x 2.54 0.100 typ 2.54 0.300 7.62 figure 5. sop footprint (case 482 and 482a) inch mm f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3150 motorola sensor device data www.motorola.com/semiconductors ! " ! motorola has developed a low cost, high volume, miniature pressure sensor package which is ideal as a submodule component or a disposable unit. the unique concept of the chip pak allows great flexibility in system design while allowing an economic solution for the designer. this new chip carrier package uses motorola's unique sensor die with its piezoresistive technology, along with the added feature of onchip, thinfilm temperature compensation and calibration. note: motorola is also offering the chip pak package in applicationspecific configurations, which will have an aspxo prefix, followed by a fourdigit number, unique to the specific customer. features: ? low cost ? integrated temperature compensation and calibration ? ratiometric to supply voltage ? polysulfone case material (medical, class v approved) ? provided in easytouse tape and reel application examples ? respiratory diagnostics ? air movement control ? controllers ? pressure switching note: the die and wire bonds are exposed on the front side of the chip pak (pressure is applied to the backside of the device). front side die and wire protection must be provided in the customer's housing. use caution when handling the devices during all processes. motorola's mpxc2011dt1/mpxc2012dt1 pressure sensor has been designed for medical usage by combining the performance of motorola's shear stress pressure sensor design and the use of biomedically approved materials. materials with a proven history in medical situations have been chosen to provide a sensor that can be used with confidence in applications, such as invasive blood pressure monitoring. it can be sterilized using ethylene oxide. the portions of the pressure sensor that are required to be biomedically approved are the rigid housing and the gel coating. the rigid housing is molded from a white, medical grade polysulfone that has passed extensive biological testing including: tissue culture test, rabbit implant, hemolysis, intracutaneous test in rabbits, and system toxicity, usp. the mpxc2011dt1 contains a silicone dielectric gel which covers the silicon piezoresistive sensing element. the gel is a nontoxic, nonallergenic elastomer system which meets all usp xx biological testing class v requirements. the properties of the gel allow it to transmit pressure uni- formly to the diaphragm surface, while isolating the internal electrical connections from the corrosive effects of fluids, such as saline solution. the gel provides electrical isolation sufficient to withstand defibrillation testing, as specified in the proposed association for the advancement of medical instrumentation (aami) standard for blood pressure trans- ducers. a biomedically approved opaque filler in the gel pre- vents bright operating room lights from affecting the performance of the sensor. the mpxc2012dt1 is a nogel option. preferred devices are motorola recommended choices for future use and best overall value.
semiconductor technical data

pressure sensors 0 to 75 mmhg (0 to 10 kpa) pin number mpxc2011dt1/mpxc2012dt1 case 423a 1 2 gnd s+ 3 4 v s s chip pak package motorola preferred device rev 2 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

3151 motorola sensor device data www.motorola.com/semiconductors maximum ratings (note) rating symbol value unit maximum pressure (backside) p max 75 kpa storage temperature t stg 25 to +85 c operating temperature t a +15 to +40 c note: exposure beyond the specified limits may cause permanent damage or degradation to the device. operating characteristics (v s = 10 vdc, t a = 25 c unless otherwise noted, p1 > p2) characteristic symbol min typ max unit pressure range (1) p op 0 e 10 kpa supply voltage (2) v s e 3 10 vdc supply current i o e 6.0 e madc full scale span (3) v fss 24 25 26 mv offset (4) v off 1.0 e 1.0 mv sensitivity d v/ d p e 2.5 e mv/kpa linearity (5) e 1.0 e 1.0 %v fss pressure hysteresis (5) (0 to 10 kpa) e e 0.1 e %v fss temperature hysteresis (5) (+15 c to +40 c) e e 0.1 e %v fss temperature effect on full scale span (5) tcv fss 1.0 e 1.0 %v fss temperature effect on offset (5) tcv off 1.0 e 1.0 mv input impedance z in 1300 e 2550 w output impedance z out 1400 e 3000 w response time (6) (10% to 90%) t r e 1.0 e ms warmup e e 20 e ms offset stability (7) e e 0.5 e %v fss notes: 1. 1.0 kpa (kilopascal) equals 0.145 psi. 2. device is ratiometric within this specified excitation range. operating the device above the specified excitation range may i nduce additional error due to device selfheating. 3. full scale span (v fss ) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 4. offset (v off ) is defined as the output voltage at the minimum rated pressure. 5. accuracy (error budget) consists of the following: ? linearity: output deviation from a straight line relationship with pressure, using end point method, over the specified pressure range. ? temperature hysteresis: output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. ? pressure hysteresis: output deviation at any pressure within the specified range, when this pressure is cycled to and from the minimum or maximum rated pressure, at 25 c. ? tcspan: output deviation at full rated pressure over the temperature range of 0 to 85 c, relative to 25 c. ? tcoffset: output deviation with minimum rated pressure applied, over the temperature range of 0 to 85 c, relative to 25 c. 6. response time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when s ubjected to a specified step change in pressure. 7. offset stability is the product's output deviation when subjected to 1000 hours of pulsed pressure, temperature cycling with bias test. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

3152 motorola sensor device data www.motorola.com/semiconductors ordering information the mpxc2011dt1/mpxc2012dt1 silicon pressure sensors are available in tape and reel. device type/order no. case no. device description marking mpxc2011dt1 423a chip pak, 1/3 gel date code, lot id mpxc2012dt1 423a chip pak, no gel date code, lot id packaging information reel size tape width quantity tape and reel 330 mm 24 mm 1000 pc/reel f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3153 motorola sensor device data www.motorola.com/semiconductors
!"$%" %"& $"$ "##%" # " " #%" # %$ "##%" ! $ !"$%" !#$ "$ motorola's mpxh6300a series sensor integrates onc hip, bipolar op amp circuitry and thin film resistor networks to provide a high output signal and temperature compensation. the small form factor and high reliability of onchip integration make the motorola pressure sensor a logical and economical choice for the system designer. the mpxh6300a series piezoresistive transducer is a stateoftheart, monolithic, signal conditioned, silicon pressure sensor. this sensor combines advanced micromachining tec hniques, thin film metallization, and bipolar semiconductor processing to provide an accurate, high level analog output signal that is proportional to applied pressure. figure 1 shows a block diagram of the internal circuitry integrated on a pressure sensor chip. features ? improved accuracy at high temperature ? available in small and super small outline packages ? 1.5% maximum error over 0 to 85 c ? ideally suited for microprocessor or microcontrollerbased systems ? temperature compensated from 40 to +125 c ? durable thermoplastic (pps) surface mount package application examples ? aviation altimeters ? industrial controls ? engine control/manifold absolute pressure (map) ? weather station and weather reporting device barometers figure 1. fully integrated pressure sensor schematic v s sensing element v out gnd thin film temperature compensation and gain stage #1 gain stage #2 and ground reference shift circuitry pins 1, 5, 6, 7 and 8 are no connects semiconductor technical data
integrated pressure sensor 20 to 304 kpa (3.0 to 42 psi) 0.3 to 4.9 volts output pin number note: pins 1, 5, 6, 7, and 8 are internal device connections. do not connect to external circuitry or ground. pin 1 is denoted by the chamfered corner of the package. 1 2 3 n/c v s gnd 5 6 7 n/c n/c n/c mpxh6300a6t1 case 1317 mpxh6300ac6t1 case 1317a 4v out 8 n/c super small outline package rev 0 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

3154 motorola sensor device data www.motorola.com/semiconductors maximum ratings (1) parametrics symbol value units maximum pressure (p1 p2) p max 1200 kpa storage temperature t stg 40 to +125 c operating temperature t a 40 to +125 c output source current @ full scale output (2) i o + 0.5 madc output sink current @ minimum pressure offset (2) i o 0.5 madc notes: 1. exposure beyond the specified limits may cause permanent damage or degradation to the device. 2. maximum output current is controlled by effective impedance from v out to gnd or v out to v s in the application circuit. operating characteristics (v s = 5.1 vdc, t a = 25 c unless otherwise noted, p1 p2.) characteristic symbol min typ max unit pressure range p op 20 e 304 kpa supply voltage (1) v s 4.74 5.1 5.46 vdc supply current i o e 6.0 10 madc minimum pressure offset (2) (0 to 85 c) @ v s = 5.1 volts v off 0.241 0.306 0.371 vdc full scale output (3) (0 to 85 c) @ v s = 5.1 volts v fso 4.847 4.912 4.977 vdc full scale span (4) (0 to 85 c) @ v s = 5.1 volts v fss 4.476 4.606 4.736 vdc accuracy (5) (0 to 85 c) e e e 1.5 %v fss sensitivity v/p e 16.2 e mv/kpa response time (6) t r e 1.0 e ms warmup time (7) e e 20 e ms offset stability (8) e e 0.25 e %v fss notes: 1. device is ratiometric within this specified excitation range. 2. offset (v off ) is defined as the output voltage at the minimum rated pressure. 3. full scale output (v fso ) is defined as the output voltage at the maximum or full rated pressure. 4. full scale span (v fss ) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 5. accuracy is the deviation in actual output from nominal output over the entire pressure range and temperature range as a perc ent of span at 25 c due to all sources of error including the following: ? linearity: output deviation from a straight line relationship with pressure over the specified pressure range. ? temperature hysteresis: output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. ? pressure hysteresis: output deviation at any pressure within the specified range, when this pressure is cycled to and from minimum or maximum rated pressure at 25 c. ? tcspan: output deviation over the temperature range of 0 to 85 c, relative to 25 c. ? tcoffset: output deviation with minimum pressure applied, over the temperature range of 0 to 85 c, relative to 25 c. 6. response time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when s ubjected to a specified step change in pressure. 7. warmup time is defined as the time required for the product to meet the specified output voltage after the pressure has been stabilized. 8. offset stability is the product's output deviation when subjected to 1000 cycles of pulsed pressure, temperature cycling with bias test. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

3155 motorola sensor device data www.motorola.com/semiconductors figure 2. cross sectional diagram ssop (not to scale) figure 3. typical application circuit (output source current operation) wire bond stainless steel cap thermoplastic case die bond sealed vacuum reference di e p1 fluoro silicone gel die coat lead frame absolute element v s pin 2 5.1 v gnd pin 3 v out pin 4 to adc 100 nf 51 k 47 pf mpxh6300a figure 2 illustrates the absolute sensing chip in the basic super small outline chip carrier (case 1317). figure 3 shows a typical application circuit (output source current operation). output (volts) 5.0 4.5 4.0 3.5 3.0 pressure (ref: to sealed vacuum) in kpa typ max min 20 35 50 65 80 95 110 125 140 155 170 185 200 215 230 245 260 275 2.5 2.0 1.5 1.0 0.5 0 290 figure 4. output versus absolute pressure transfer function: v out = v s * (.00318*p.00353) error v s = 5.1 vdc temp = 0 to 85 c 305 figure 4 shows the sensor output signal relative to pres- sure input. typical minimum and maximum output curves are shown for operation over 0 to 85 c temperature range. the output will saturate outside of the rated pressure range. a fluorosilicone gel isolates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the s ilicon diaphragm. the mpxh6300a series pressure sensor operating characteris- tics, internal reliability and qualification tests are based on use of dry air as the pressure media. media other than dry air may have adverse effects on sensor performance and longterm reliability. contact the factory for information re- garding media compatibility in your application. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

3156 motorola sensor device data www.motorola.com/semiconductors transfer function (mpxh6300a) nominal transfer value: v out = v s x (0.00318 x p 0.00353) (pressure error x temp. factor x 0.00318 x v s ) v s = 5.1 0.36 vdc temperature error band mpxh6300a series break points temp multiplier 40 3 0 to 85 1 125 3 temperature in c 4.0 3.0 2.0 0.0 1.0 40 20 0 20 40 60 140 120 100 80 temperature error factor note: the temperature multiplier is a linear response from 0 c to 40 c and from 85 c to 125 c pressure error band error limits for pressure 3.0 2.0 1.0 1.0 2.0 4.0 0.0 20 pressure (in kpa) pressure error (kpa) pressure error (max) 20 to 304 (kpa) 4.0 (kpa) 60 100 4.0 3.0 140 180 220 260 300 ordering information e super small outline package device type options case no. mpx series order no. packing options marking basic element absolute, element only 1317 mpxh6300a6u rails mpxh6300a absolute, element only 1317 mpxh6300a6t1 tape and reel mpxh6300a ported element absolute, axial port 1317a mpxh6300ac6u rails mpxh6300a absolute, axial port 1317a mpxh6300ac6t1 tape and reel mpxh6300a f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

3157 motorola sensor device data www.motorola.com/semiconductors surface mounting information minimum recommended footprint for super small outline packages surface mount board layout is a critical portion of the total design. the footprint for the semiconductor package must be the correct size to ensure proper solder connection inter- face between the board and the package. with the correct pad geometry, the packages will selfalign when subjected to a solder reflow process. it is always recommended to fabri- cate boards with a solder mask layer to avoid bridging and/or shorting between solder pads, especially on tight tolerances and/or tight layouts. figure 5. ssop footprint (case 1317 and 1317a) 0.027 typ 8x 0.69 0.053 typ 8x 1.35 inch mm 0.387 9.83 0.150 3.81 0.050 1.27 typ f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3158 motorola sensor device data www.motorola.com/semiconductors "# !" " !!# ! ! the mpxm2010 device is a silicon piezoresistive pressure sensors providing a highly accurate and linear voltage output e directly proportional to the applied pressure. the sensor is a single, monolithic silicon diaphragm with the strain gauge and a thinfilm resistor network integrated onchip. the chip is laser trimmed for precise span and offset calibration and temperature compensation. features ? temperature compensated over 0 c to + 85 c ? available in easytouse tape & reel ? ratiometric to supply voltage ? gauge ported & non ported options application examples ? respiratory diagnostics ? air movement control ? controllers ? pressure switching figure 1 shows a block diagram of the internal circuitry on the standalone pressure sensor chip. figure 1. temperature compensated pressure sensor schematic v s 3 sensing element thin film temperature compensation and calibration circuitry 2 4 v out+ v out 1 gnd voltage output versus applied differential pressure the differential voltage output of the sensor is directly proportional to the differential pressure applied. the output voltage of the differential or gauge sensor increases with increasing pressure applied to the pressure side (p1) relative to the vacuum side (p2). similarly, output voltage increases as increasing vacuum is applied to the vacuum side (p2) relative to the pressure side (p1). preferred devices are motorola recommended choices for future use and best overall value. semiconductor technical data
0 to 10 kpa (0 to 1.45 psi) 25 mv full scale span (typical) pin number 1 2 gnd +v out 3 4 v s v out motorola preferred device mpxm2010d/dt1 case 1320 mpxm2010gs/gst1 case 1320a scale 1:1 scale 1:1 mpak package rev 1 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

3159 motorola sensor device data www.motorola.com/semiconductors maximum ratings (note) rating symbol value unit maximum pressure (p1 > p2) p max 75 kpa storage temperature t stg 40 to +125 c operating temperature t a 40 to +125 c note: exposure beyond the specified limits may cause permanent damage or degradation to the device. operating characteristics (v s = 10 vdc, t a = 25 c unless otherwise noted, p1 > p2) characteristic symbol min typ max unit pressure range (1) p op 0 e 10 kpa supply voltage (2) v s e 10 16 vdc supply current i o e 6.0 e madc full scale span (3) v fss 24 25 26 mv offset (4) v off 1.0 e 1.0 mv sensitivity d v/ d p e 2.5 e mv/kpa linearity (5) e 1.0 e 1.0 %v fss pressure hysteresis (5) (0 to 10 kpa) e e 0.1 e %v fss temperature hysteresis (5) ( 40 c to +125 c) e e 0.5 e %v fss temperature effect on full scale span (5) tcv fss 1.0 e 1.0 %v fss temperature effect on offset (5) tcv off 1.0 e 1.0 mv input impedance z in 1000 e 2550 w output impedance z out 1400 e 3000 w response time (6) (10% to 90%) t r e 1.0 e ms warmup e e 20 e ms offset stability (7) e e 0.5 e %v fss notes: 1. 1.0 kpa (kilopascal) equals 0.145 psi. 2. device is ratiometric within this specified excitation range. operating the device above the specified excitation range may i nduce additional error due to device selfheating. 3. full scale span (v fss ) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 4. offset (v off ) is defined as the output voltage at the minimum rated pressure. 5. accuracy (error budget) consists of the following: ? linearity: output deviation from a straight line relationship with pressure, using end point method, over the specified pressure range. ? temperature hysteresis: output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. ? pressure hysteresis: output deviation at any pressure within the specified range, when this pressure is cycled to and from the minimum or maximum rated pressure, at 25 c. ? tcspan: output deviation at full rated pressure over the temperature range of 0 to 85 c, relative to 25 c. ? tcoffset: output deviation with minimum rated pressure applied, over the temperature range of 0 to 85 c, relative to 25 c. 6. response time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when s ubjected to a specified step change in pressure. 7. offset stability is the product's output deviation when subjected to 1000 hours of pulsed pressure, temperature cycling with bias test. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

3160 motorola sensor device data www.motorola.com/semiconductors linearity linearity refers to how well a transducer's output follows the equation: v out = v off + sensitivity x p over the operating pressure range. there are two basic methods for calculating nonlinearity: (1) end point straight line fit (see figure 2) or (2) a least squares best line fit. while a least squares fit gives the abest caseo linearity error (lower numerical value), the calculations required are burdensome. conversely, an end point fit will give the aworst caseo error (often more desirable in error budget calculations) and the cal- culations are more straightforward for the user. motorola's specified pressure sensor linearities are based on the end point straight line method measured at the midrange pressure. figure 2. linearity specification comparison least square deviation relative voltage output pressure (% fullscale) 0 50 100 end point straight line fit exaggerated performance curve least squares fit straight line deviation offset onchip temperature compensation and calibration figure 3 shows the minimum, maximum and typical output characteristics of the mpxm2010 series at 25 c. the output is directly proportional to the differential pressure and is es- sentially a straight line. a silicone gel isolates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the silicon diaphragm. figure 3. output versus pressure differential min typ offset (typ) 30 20 15 10 5 output (mvdc) 25 0 5 kpa psi 2.5 0.362 5 0.725 7.5 1.09 10 1.45 a max span range (typ) v s = 10 vdc t a = 25 c p1 > p2 ordering information device type options case no device type options case no . mpxm2010d nonported 1320 mpxm2010dt1 nonported, tape and reel 1320 mpxm2010gs ported 1320a mpxm2010gst1 ported, tape and reel 1320a f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3161 motorola sensor device data www.motorola.com/semiconductors !#$! "# !# !""$! "!" the mpxm2053 device is a silicon piezoresistive pressure sensor providing a highly accurate and linear voltage output e directly proportional to the applied pressure. the sensor is a single, monolithic silicon diaphragm with the strain gauge and a thinfilm resistor network integrated onchip. the chip is laser trimmed for precise span and offset calibration and temperature compensation. features ? temperature compensated over 0 c to + 85 c ? available in easytouse tape & reel ? ratiometric to supply voltage ? gauge ported & non ported options application examples ? pump/motor controllers ? robotics ? level indicators ? medical diagnostics ? pressure switching ? noninvasive blood pressure measurement figure 1 shows a block diagram of the internal circuitry on the standalone pressure sensor chip. figure 1. temperature compensated pressure sensor schematic v s 3 xducer sensing element thin film temperature compensation and calibration circuitry 2 4 v out+ v out 1 gnd voltage output versus applied differential pressure the differential voltage output of the sensor is directly proportional to the differential pressure applied. the output voltage of the differential or gauge sensor increases with increasing pressure applied to the pressure side (p1) relative to the vacuum side (p2). similarly, output voltage increases as increasing vacuum is applied to the vacuum side (p2) relative to the pressure side (p1). preferred devices are motorola recommended choices for future use and best overall value. semiconductor technical data

0 to 50 kpa (0 to 7.25 psi) 40 mv full scale span (typical) pin number 1 2 gnd +v out 3 4 v s v out motorola preferred device mpxm2053d/dt1 case 1320 mpxm2053gs/gst1 case 1320a scale 1:1 scale 1:1 mpak package rev 1 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

3162 motorola sensor device data www.motorola.com/semiconductors maximum ratings (note) rating symbol value unit maximum pressure (p1 > p2) p max 200 kpa storage temperature t stg 40 to +125 c operating temperature t a 40 to +125 c note: exposure beyond the specified limits may cause permanent damage or degradation to the device. operating characteristics (v s = 10 vdc, t a = 25 c unless otherwise noted, p1 > p2) characteristic symbol min typ max unit pressure range (1) p op 0 e 50 kpa supply voltage (2) v s e 10 16 vdc supply current i o e 6.0 e madc full scale span (3) v fss 38.5 40 41.5 mv offset (4) v off 1.0 e 1.0 mv sensitivity d v/ d p e 0.8 e mv/kpa linearity (5) e 0.6 e 0.4 %v fss pressure hysteresis (5) (0 to 50 kpa) e e 0.1 e %v fss temperature hysteresis (5) ( 40 c to +125 c) e e 0.5 e %v fss temperature effect on full scale span (5) tcv fss 2.0 e 2.0 %v fss temperature effect on offset (5) tcv off 1.0 e 1.0 mv input impedance z in 1000 e 2500 w output impedance z out 1400 e 3000 w response time (6) (10% to 90%) t r e 1.0 e ms warmup e e 20 e ms offset stability (7) e e 0.5 e %v fss notes: 1. 1.0 kpa (kilopascal) equals 0.145 psi. 2. device is ratiometric within this specified excitation range. operating the device above the specified excitation range may i nduce additional error due to device selfheating. 3. full scale span (v fss ) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 4. offset (v off ) is defined as the output voltage at the minimum rated pressure. 5. accuracy (error budget) consists of the following: ? linearity: output deviation from a straight line relationship with pressure, using end point method, over the specified pressure range. ? temperature hysteresis: output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. ? pressure hysteresis: output deviation at any pressure within the specified range, when this pressure is cycled to and from the minimum or maximum rated pressure, at 25 c. ? tcspan: output deviation at full rated pressure over the temperature range of 0 to 85 c, relative to 25 c. ? tcoffset: output deviation with minimum rated pressure applied, over the temperature range of 0 to 85 c, relative to 25 c. 6. response time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when s ubjected to a specified step change in pressure. 7. offset stability is the product's output deviation when subjected to 1000 hours of pulsed pressure, temperature cycling with bias test. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

3163 motorola sensor device data www.motorola.com/semiconductors linearity linearity refers to how well a transducer's output follows the equation: v out = v off + sensitivity x p over the operating pressure range. there are two basic methods for calculating nonlinearity: (1) end point straight line fit (see figure 2) or (2) a least squares best line fit. while a least squares fit gives the abest caseo linearity error (lower numerical value), the calculations required are burdensome. conversely, an end point fit will give the aworst caseo error (often more desirable in error budget calculations) and the cal- culations are more straightforward for the user. motorola's specified pressure sensor linearities are based on the end point straight line method measured at the midrange pressure. figure 2. linearity specification comparison least square deviation relative voltage output pressure (% fullscale) 0 50 100 end point straight line fit exaggerated performance curve least squares fit straight line deviation offset onchip temperature compensation and calibration figure 3 shows the minimum, maximum and typical output characteristics of the mpxm2053 series at 25 c. the output is directly proportional to the differential pressure and is es- sentially a straight line. a silicone gel isolates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the silicon diaphragm. figure 3. output versus pressure differential output (mvdc) kpa psi 40 35 30 25 15 10 5 0 5 0 12.5 1.8 25 3.6 37.5 5.4 50 7.25 span range (typ) offset (typ) 20 max typ min v s = 10 vdc t a = 25 c p1 > p2 ordering information device type options case no device type options case no . mpxm2053d nonported 1320 mpxm2053dt1 nonported, tape and reel 1320 mpxm2053gs ported 1320a mpxm2053gst1 ported, tape and reel 1320a f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3164 motorola sensor device data www.motorola.com/semiconductors "# !" " !!# ! ! the mpxm2102 device is a silicon piezoresistive pressure sensors providing a highly accurate and linear voltage output e directly proportional to the applied pressure. the sensor is a single, monolithic silicon diaphragm with the strain gauge and a thinfilm resistor network integrated onchip. the chip is laser trimmed for precise span and offset calibration and temperature compensation. features ? temperature compensated over 0 c to + 85 c ? available in easy-to-use tape & reel ? ratiometric to supply voltage ? gauge ported & non ported options application examples ? pump/motor controllers ? robotics ? level indicators ? medical diagnostics ? pressure switching ? barometers ? altimeters figure 1 shows a block diagram of the internal circuitry on the standalone pressure sensor chip. figure 1. temperature compensated pressure sensor schematic v s 3 xducer sensing element thin film temperature compensation and calibration circuitry 2 4 v out+ v out 1 gnd voltage output versus applied differential pressure the differential voltage output of the sensor is directly proportional to the differential pressure applied. the output voltage of the differential or gauge sensor increases with increasing pressure applied to the pressure side (p1) relative to the vacuum side (p2). similarly, output voltage increases as increasing vacuum is applied to the vacuum side (p2) relative to the pressure side (p1). preferred devices are motorola recommended choices for future use and best overall value. semiconductor technical data
0 to 100 kpa (0 to 14.5 psi) 40 mv full scale span (typical) pin number 1 2 gnd +v out 3 4 v s v out motorola preferred device case 1320 case 1320a scale 1:1 scale 1:1 mpak package rev 1 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

3165 motorola sensor device data www.motorola.com/semiconductors maximum ratings (note) rating symbol value unit maximum pressure (p1 > p2) p max 200 kpa storage temperature t stg 40 to +125 c operating temperature t a 40 to +125 c note: exposure beyond the specified limits may cause permanent damage or degradation to the device. operating characteristics (v s = 10 vdc, t a = 25 c unless otherwise noted, p1 > p2) characteristic symbol min typ max unit pressure range (1) p op 0 e 100 kpa supply voltage (2) v s e 10 16 vdc supply current i o e 6.0 e madc full scale span (3) v fss 38.5 40 41.5 mv offset (4) mpxm2102d/g series mpxm2102a series v off 1.0 2.0 e e 1.0 2.0 mv sensitivity d v/ d p e 0.4 e mv/kpa linearity (5) mpxm2102d/g series mpxm2102a series e e 0.6 1.0 e e 0.4 1.0 %v fss pressure hysteresis (5) (0 to 100 kpa) e e 0.1 e %v fss temperature hysteresis (5) ( 40 c to +125 c) e e 0.5 e %v fss temperature effect on full scale span (5) tcv fss 2.0 e 2.0 %v fss temperature effect on offset (5) tcv off 1.0 e 1.0 mv input impedance z in 1000 e 2500 w output impedance z out 1400 e 3000 w response time (6) (10% to 90%) t r e 1.0 e ms warmup e e 20 e ms offset stability (7) e e 0.5 e %v fss notes: 1. 1.0 kpa (kilopascal) equals 0.145 psi. 2. device is ratiometric within this specified excitation range. operating the device above the specified excitation range may i nduce additional error due to device selfheating. 3. full scale span (v fss ) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 4. offset (v off ) is defined as the output voltage at the minimum rated pressure. 5. accuracy (error budget) consists of the following: ? linearity: output deviation from a straight line relationship with pressure, using end point method, over the specified pressure range. ? temperature hysteresis: output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. ? pressure hysteresis: output deviation at any pressure within the specified range, when this pressure is cycled to and from the minimum or maximum rated pressure, at 25 c. ? tcspan: output deviation at full rated pressure over the temperature range of 0 to 85 c, relative to 25 c. ? tcoffset: output deviation with minimum rated pressure applied, over the temperature range of 0 to 85 c, relative to 25 c. 6. response time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when s ubjected to a specified step change in pressure. 7. offset stability is the product's output deviation when subjected to 1000 hours of pulsed pressure, temperature cycling with bias test. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

3166 motorola sensor device data www.motorola.com/semiconductors linearity linearity refers to how well a transducer's output follows the equation: v out = v off + sensitivity x p over the operating pressure range. there are two basic methods for calculating nonlinearity: (1) end point straight line fit (see figure 2) or (2) a least squares best line fit. while a least squares fit gives the abest caseo linearity error (lower numerical value), the calculations required are burdensome. conversely, an end point fit will give the aworst caseo error (often more desirable in error budget calculations) and the cal- culations are more straightforward for the user. motorola's specified pressure sensor linearities are based on the end point straight line method measured at the midrange pressure. figure 2. linearity specification comparison least square deviation relative voltage output pressure (% fullscale) 0 50 100 end point straight line fit exaggerated performance curve least squares fit straight line deviation offset onchip temperature compensation and calibration figure 3 shows the minimum, maximum and typical output characteristics of the mpxm2102 series at 25 c. the output is directly proportional to the differential pressure and is es- sentially a straight line. a silicone gel isolates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the silicon diaphragm. figure 3. output versus pressure differential output (mvdc) kpa psi 40 35 30 25 15 10 5 0 5 025 3.62 50 7.25 75 10.87 100 14.5 span range (typ) offset (typ) 20 typ min v s = 10 vdc t a = 25 c p1 > p2 max ordering information device type options case type device type options case type mpxm2102d nonported 1320 mpxm2102dt1 nonported, tape and reel 1320 mpxm2102gs ported 1320a mpxm2102gst1 ported, tape and reel 1320a mpxm2102a nonported 1320 mpxm2102at1 nonported, tape and reel 1320 mpxm2102as ported 1320a mpxm2102ast1 ported, tape and reel 1320a f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3167 motorola sensor device data www.motorola.com/semiconductors !" ! ! " the mpxm2202 device is a silicon piezoresistive pressure sensors providing a highly accurate and linear voltage output e directly proportional to the applied pressure. the sensor is a single, monolithic silicon diaphragm with the strain gauge and a thinfilm resistor network integrated onchip. the chip is laser trimmed for precise span and offset calibration and temperature compensation. features ? temperature compensated over 0 c to + 85 c ? available in easy-to-use tape & reel ? ratiometric to supply voltage ? gauge ported & non ported options application examples ? pump/motor controllers ? robotics ? level indicators ? medical diagnostics ? pressure switching ? barometers ? altimeters figure 1 shows a block diagram of the internal circuitry on the standalone pressure sensor chip. figure 1. temperature compensated pressure sensor schematic v s 3 xducer sensing element thin film temperature compensation and calibration circuitry 2 4 v out+ v out 1 gnd voltage output versus applied differential pressure the differential voltage output of the sensor is directly proportional to the differential pressure applied. the output voltage of the differential or gauge sensor increases with increasing pressure applied to the pressure side (p1) relative to the vacuum side (p2). similarly, output voltage increases as increasing vacuum is applied to the vacuum side (p2) relative to the pressure side (p1). preferred devices are motorola recommended choices for future use and best overall value.
semiconductor technical data 0 to 200 kpa (0 to 29 psi) 40 mv full scale span (typical) motorola preferred device pin number 1 2 gnd +v out 3 4 v s v out case 1320 case 1320a scale 1:1 scale 1:1 mpak package rev 0 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

3168 motorola sensor device data www.motorola.com/semiconductors maximum ratings (note) rating symbol value unit maximum pressure (p1 > p2) p max 400 kpa storage temperature t stg 40 to +125 c operating temperature t a 40 to +125 c note: exposure beyond the specified limits may cause permanent damage or degradation to the device. operating characteristics (v s = 10 vdc, t a = 25 c unless otherwise noted, p1 > p2) characteristic symbol min typ max unit pressure range (1) p op 0 e 200 kpa supply voltage (2) v s e 10 16 vdc supply current i o e 6.0 e madc full scale span (3) v fss 38.5 40 41.5 mv offset (4) mpxm2202d/g series mpxm2202a series v off 1.0 2.0 e e 1.0 2.0 mv sensitivity d v/ d p e 0.2 e mv/kpa linearity (5) mpxm2202d/g series mpxm2202a series e e 0.6 1.0 e e 0.4 1.0 %v fss pressure hysteresis (5) (0 to 100 kpa) e e 0.1 e %v fss temperature hysteresis (5) ( 40 c to +125 c) e e 0.5 e %v fss temperature effect on full scale span (5) tcv fss 2.0 e 2.0 %v fss temperature effect on offset (5) tcv off 1.0 e 1.0 mv input impedance z in 1000 e 2500 w output impedance z out 1400 e 3000 w response time (6) (10% to 90%) t r e 1.0 e ms warmup e e 20 e ms offset stability (7) e e 0.5 e %v fss notes: 1. 1.0 kpa (kilopascal) equals 0.145 psi. 2. device is ratiometric within this specified excitation range. operating the device above the specified excitation range may i nduce additional error due to device selfheating. 3. full scale span (v fss ) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 4. offset (v off ) is defined as the output voltage at the minimum rated pressure. 5. accuracy (error budget) consists of the following: ? linearity: output deviation from a straight line relationship with pressure, using end point method, over the specified pressure range. ? temperature hysteresis: output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. ? pressure hysteresis: output deviation at any pressure within the specified range, when this pressure is cycled to and from the minimum or maximum rated pressure, at 25 c. ? tcspan: output deviation at full rated pressure over the temperature range of 0 to 85 c, relative to 25 c. ? tcoffset: output deviation with minimum rated pressure applied, over the temperature range of 0 to 85 c, relative to 25 c. 6. response time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when s ubjected to a specified step change in pressure. 7. offset stability is the product's output deviation when subjected to 1000 hours of pulsed pressure, temperature cycling with bias test. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

3169 motorola sensor device data www.motorola.com/semiconductors linearity linearity refers to how well a transducer's output follows the equation: v out = v off + sensitivity x p over the operating pressure range. there are two basic methods for calculating nonlinearity: (1) end point straight line fit (see figure 2) or (2) a least squares best line fit. while a least squares fit gives the abest caseo linearity error (lower numerical value), the calculations required are burdensome. conversely, an end point fit will give the aworst caseo error (often more desirable in error budget calculations) and the cal- culations are more straightforward for the user. motorola's specified pressure sensor linearities are based on the end point straight line method measured at the midrange pressure. figure 2. linearity specification comparison least square deviation relative voltage output pressure (% fullscale) 0 50 100 end point straight line fit exaggerated performance curve least squares fit straight line deviation offset onchip temperature compensation and calibration figure 3 shows the minimum, maximum and typical output characteristics of the mpxm2202 series at 25 c. the output is directly proportional to the differential pressure and is es- sentially a straight line. a silicone gel isolates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the silicon diaphragm. figure 3. output versus pressure differential 40 35 30 25 20 15 10 5 0 5 050 7.25 100 14.5 150 21.75 200 29 pressure output (mvdc) span range (typ) offset kpa psi v s = 10 vdc t a = 25 c p1 > p2 25 75 125 175 max typ min ordering information device type/order no options case type device type/order no . options case type mpxm2202d nonported 1320 mpxm2202dt1 nonported, tape and reel 1320 mpxm2202gs ported 1320a mpxm2202gst1 ported, tape and reel 1320a mpxm2202a nonported 1320 mpxm2202at1 nonported, tape and reel 1320 mpxm2202as ported 1320a mpxm2202ast1 ported, tape and reel 1320a f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3170 motorola sensor device data www.motorola.com/semiconductors $"$ "##%" # " ! $ !"$%" !#$ "$ the mpxv4006g series piezoresistive transducer is a stateoftheart monolithic silicon pressure sensor designed for a wide range of applications, but particularly those employing a microcontroller or microprocessor with a/d inputs. this sensor combines a highly sensitive implanted strain gauge with advanced micromachining techniques, thinfilm metallization, and bipolar processing to provide an accurate, high level analog output signal that is proportional to the applied pressure. features ? temperature compensated over 10 to 60 c ? ideally suited for microprocessor or microcontroller based systems ? available in gauge surface mount (smt) or through hole (dip) configurations ? durable thermoplastic (pps) package figure 1. fully integrated pressure sensor schematic v s sensing element v out gnd thin film temperature compensation and gain stage #1 gain stage #2 and ground reference shift circuitry pins 1, 5, 6, 7, and 8 are no connects for small outline package device replaces mpxt4006d/d semiconductor technical data
integrated pressure sensor 0 to 6 kpa (0 to 0.87 psi) 0.2 to 4.7 v output small outline package throughhole pin number 1 2 3 n/c v s gnd 5 6 7 n/c n/c n/c 4v out 8 n/c mpxv4006gc7u case 482c mpxv4006g7u case 482b note: pins 1, 5, 6, 7, and 8 are internal device connections. do not connect to external circuitry or ground. pin 1 is noted by the notch in the lead. mpxv4006g6u case 482 mpxv4006gc6u case 482a small outline package surface mount mpxv4006dp case 1351 mpxv4006gp case 1369 j rev 4 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

3171 motorola sensor device data www.motorola.com/semiconductors maximum ratings (note) parametrics symbol value unit maximum pressure (p1 > p2) p max 24 kpa storage temperature t stg 30 to +100 c operating temperature t a +10 to +60 c note: exposure beyond the specified limits may cause permanent damage or degradation to the device. operating characteristics (v s = 5.0 vdc, t a = 25 c unless otherwise noted, p1 > p2. decoupling circuit shown in figure 3 required to meet electrical specifications.) characteristic symbol min typ max unit pressure range p op 0 e 6.0 kpa supply voltage (1) v s 4.75 5.0 5.25 vdc supply current i s e e 10 madc full scale span (2) (rl = 51k w ) v fss e 4.6 e v offset (3)(5) (rl = 51k w ) v off 0.100 0.225 0.430 v sensitivity v/p e 766 e mv/kpa accuracy (4)(5) (10 to 60 c) e e e 5.0 %v fss notes: 1. device is ratiometric within this specified excitation range. 2. full scale span (v fss ) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 3. offset (v off ) is defined as the output voltage at the minimum rated pressure. 4. accuracy (error budget) consists of the following: ? linearity: output deviation from a straight line relationship with pressure over the specified pressure range. ? temperature hysteresis: output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. ? pressure hysteresis: output deviation at any pressure within the specified range, when this pressure is cycled to and from the minimum or maximum rated pressure, at 25 c. ? offset stability: output deviation, after 1000 temperature cycles, 30 to 100 c, and 1.5 million pressure cycles, with minimum rated pressure applied. ? tcspan: output deviation over the temperature range of 10 to 60 c, relative to 25 c. ? tcoffset: output deviation with minimum rated pressure applied, over the temperature range of 10 to 60 c, relative to 25 c. ? variation from nominal: the variation from nominal values, for offset or full scale span, as a percent of v fss , at 25 c. 5. auto zero at factory installation: due to the sensitivity of the mpxv4006g, external mechanical stresses and mounting positio n can affect the zero pressure output reading. to obtain the 5% fss accuracy, the device output must be aautozeroed'' after installation. autozeroing is defined as storing the zero pressure output reading and subtracting this from the device's output during normal operations. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

3172 motorola sensor device data www.motorola.com/semiconductors onchip temperature compensation, calibration and signal conditioning the performance over temperature is achieved by inte- grating the shearstress strain gauge, temperature com- pensation, calibration and signal conditioning circuitry onto a single monolithic chip. figure 2 illustrates the gauge configuration in the basic chip carrier (case 482). a fluorosilicone gel isolates the die surface and wire bonds from the environment, while allowing the pres- sure signal to be transmitted to the silicon diaphragm. the mpxv4006g series sensor operating characteristics are based on use of dry air as pressure media. media, other than dry air, may have adverse effects on sensor performance and longterm reliability. internal reliability and qualification test for dry air, and other media, are available from the factory. contact the factory for information regarding media tolerance in your application. figure 3 shows the recommended decoupling circuit for in- terfacing the output of the integrated sensor to the a/d input of a microprocessor or microcontroller. proper decoupling of the power supply is recommended. figure 4 shows the sensor output signal relative to pres- sure input. typical, minimum and maximum output curves are shown for operation over a temperature range of 10 c to 60 c using the decoupling circuit shown in figure 3. the output will saturate outside of the specified pressure range. figure 2. crosssectional diagram (not to scale) figure 3. recommended power supply decoupling and output filtering recommendations. for additional output filtering, please refer to application note an1646. figure 4. output versus pressure differential max differential pressure (kpa) 5.0 4.0 3.0 2.0 0 output (v) 4.5 3.5 2.5 1.5 transfer function: v out = v s *[(0.1533*p) + 0.045] 5% v fss v s = 5.0 v 0.25 vdc temp = 10 to 60 c 1.0 0.5 min typical 0 36 (see note 5 in operating characteristics) 1.0 f ips 470 pf output vs 5 v 0.01 f gnd vout fluoros i l i cone gel die coat wire bond differential sensing element thermoplastic case sta i nless steel cap lead frame p1 p2 die bond di e f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

3173 motorola sensor device data www.motorola.com/semiconductors pressure (p1)/vacuum (p2) side identification table motorola designates the two sides of the pressure sensor as the pressure (p1) side and the vacuum (p2) side. the pressure (p1) side is the side containing silicone gel which isolates the die from the environment. the motorola pres- sure sensor is designed to operate with positive differential pressure applied, p1 > p2. the pressure (p1) side may be identified by using the table below: part number case type pressure (p1) side identifier mpxv4006g6u/t1 482 stainless steel cap mpxv4006gc6u/t1 482a side with port attached mpxv4006g7u 482b stainless steel cap mpxv4006gc7u 482c side with port attached mpxv4006gp 1369 side with port attached mpxv4006dp 1351 side with part marking ordering information mpxv4006g series pressure sensors are available in the basic element package or with pressure ports. two packing options are offered for the 482 and 482a case configurations. device type options case no. mpx series order no. packing options marking basic element element only 482 mpxv4006g6u rails mpxv4006g element only 482 mpxv4006g6t1 tape and reel mpxv4006g element only 482 mpxv4006g7u rails mpxv4006g ported element axial port 482a mpxv4006gc6u rails mpxv4006g axial port 482a mpxv4006gc6t1 tape and reel mpxv4006g axial port 482a mpxv4006gc7u rails mpxv4006g side port 1369 mpxv4006gp trays mpxv4006g dual port 1351 mpxv4006dp trays mpxv4006g minimum recommended footprint for surface mounted applications surface mount board layout is a critical portion of the total design. the footprint for the surface mount packages must be the correct size to ensure proper solder connection inter- face between the board and the package. with the correct footprint, the packages will self align when subjected to a sol- der reflow process. it is always recommended to design boards with a solder mask layer to avoid bridging and short- ing between solder pads. 0.660 16.76 0.060 typ 8x 1.52 0.100 typ 8x 2.54 0.100 typ 8x 2.54 0.300 7.62 figure 5. sop footprint (case 482) inch mm scale 2:1 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3174 motorola sensor device data www.motorola.com/semiconductors
#!# !""$! "! # !#$! "# !# the mpxv4115v series piezoresistive transducer is a stateoftheart monolithic silicon pressure sensor designed for a wide range of applications, particularly those employing a microcontroller with a/d inputs. this transducer combines advanced micromachining techniques, thinfilm metallization and bipolar processing to provide an accurate, highlevel analog output signal that is proportional to the applied pressure/vac- uum. the small form factor and high reliability of onchip integration make the motorola sensor a logical and economical choice for the automotive system designer. figure 1 shows a block diagram of the internal circuitry integrated on a pressure sensor chip. features ? 1.5 % maximum error over 0 to 85 c ? temperature compensated from 40 + 125 c ? ideally suited for microprocessor or microcontrollerbased systems ? durable thermoplastic (pps) surface mount package application examples ? vacuum pump monitoring ? brake booster monitoring figure 1. fully integrated pressure sensor schematic v s sensing element v out gnd thin film temperature compensation and gain stage #1 gain stage #2 and ground reference shift circuitry pins 1, 5, 6, 7 and 8 are no connects for small outline package device semiconductor technical data
integrated pressure sensor 115 to 0 kpa (16.7 to 2.2 psi) 0.2 to 4.6 v output pin number 1 2 3 v out gnd 5 6 7 n/c n/c n/c 4 v s 8 n/c n/c note: pins 1, 5, 6, 7, and 8 are internal device connections. do not connect to external circuitry or ground. pin 1 is noted by the notch in the lead. mpxv4115vc6u case 482a small outline package mpxv4115v6u case 482 rev 1 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

3175 motorola sensor device data www.motorola.com/semiconductors maximum ratings (note) parametrics symbol value unit maximum pressure p max 400 kpa storage temperature t stg 40 to + 125 c operating temperature t a 40 to + 125 c note: exposure beyond the specified limits may cause permanent damage or degradation to the device. operating characteristics (v s = 5 vdc, t a = 25 c unless otherwise noted. decoupling circuit shown in figure 3 required to meet electrical specifications.) characteristic symbol min typ max unit pressure range (differential mode, vacuum on metal cap side, atmo- spheric pressure on back side) p op 115 e 0 kpa supply voltage (1) v s 4.75 5 5.25 vdc supply current i o e 6.0 10 madc full scale output (2) (0 to 85 c) (pdiff = 0 kpa) 2 v fso 4.535 4.6 4.665 vdc full scale span (3) (0 to 85 c) @vs = 5.0 v v fss 4.4 vdc accuracy (4) (0 to 85 c) e e 1.5% %v fss sensitivity v/p e 38.26 e mv/kpa response time (5) t r e 1.0 e ms output source current at full scale output i o e 0.1 e madc warmup time (6) e e 20 e ms offset stability (7) e 0.5 e %v fss notes: 1. device is ratiometric within the specified excitation voltage range. 2. fullscale output is defined as the output voltage at the maximum or fullrated pressure. 3. fullscale span is defined as the algebraic difference between the output voltage at fullrated pressure and the output volta ge at the mini- mumrated pressure. 4. accuracy is the deviation in actual output from nominal output over the entire pressure range and temperature range as a perc ent of span at 25 c due to all sources of errors, including the following: ? linearity: output deviation from a straight line relationship with pressure over the specified pressure range. ? temperature hysteresis: output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. ? pressure hysteresis: output deviation at any pressure within the specified range, when this pressure is cycled to and from minimum or maximum rated pressure at 25 c. ? tcspan: output deviation over the temperature range of 0 to 85 c, relative to 25 c. ? tcoffset: output deviation with minimum pressure applied, over the temperature range of 0 to 85 c, relative to 25 c. 5. response time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when s ubjected to a specified step change in pressure. 6. warmup time is defined as the time required for the product to meet the specified output voltage after the pressure has been stabilized. 7. offset stability is the product's output deviation when subjected to 1000 cycles of pulsed pressure, temperature cycling with bias test. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

3176 motorola sensor device data www.motorola.com/semiconductors onchip temperature compensation, calibration and signal conditioning the performance over temperature is achieved by inte- grating the shearstress strain gauge, temperature com- pensation, calibration and signal conditioning circuitry onto a single monolithic chip. figure 2 illustrates the gauge configuration in the basic chip carrier (case 482). a fluorosilicone gel isolates the die surface and wire bonds from the environment, while allowing the pres- sure signal to be transmitted to the silicon diaphragm. the mpxv4115v series sensor operating characteristics are based on use of dry air as pressure media. media, other than dry air, may have adverse effects on sensor performance and longterm reliability. internal reliability and qualification test for dry air, and other media, are available from the factory. contact the factory for information regarding media tolerance in your application. figure 3 shows the recommended decoupling circuit for interfacing the output of the integrated sensor to the a/d in- put of a microprocessor or microcontroller. proper decoup- ling of the power supply is recommended. figure 4 shows the sensor output signal relative to differ- ential pressure input. typical, minimum and maximum out- put curves are shown for operation over a temperature range of 0 c to 85 c using the decoupling circuit shown in figure 3. the output will saturate outside of the specified pressure range. figure 2. crosssectional diagram (not to scale) 1.0 f ips 470 pf output vs 5 v 0.01 f gnd vout figure 3. recommended power supply decoupling and output filtering. for additional output filtering, please refer to application note an1646. fluorosilicone gel die coat wire bond differential sensing element thermoplastic case stainless steel cap lead frame p1 p2 die bond die figure 4. applied vacuum in kpa (below atmospheric pressure) max transfer function: v out = v s *[(0.007652*p) + 0.92] (pressure error *temp factor*0.007652*v s ) v s = 5.0 v 0.25 vdc temp = 085 c min 115 95 75 55 35 15 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 v out vs. vacuum transfer function mpxv4115v output (volts) f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

3177 motorola sensor device data www.motorola.com/semiconductors ordering information the mpxv4115v series pressure sensors are available in the basic element package or with a pressure port. two packing options are also offered. device type case no packing options device marking device type case no . packing options device marking mpxv4115v6u 482 rails mpxv4115v mpxv4115v6t1 482 tape and reel mpxv4115v mpxv4115vc6u 482a rails mpxv4115v minimum recommended footprint for surface mounted applications surface mount board layout is a critical portion of the total design. the footprint for the surface mount packages must be the correct size to ensure proper solder connection inter- face between the board and the package. with the correct fottprint, the packages will self align when subjected to a solder reflow process. it is always recommended to design boards with a solder mask layer to avoid bridging and short- ing between solder pads. 0.660 16.76 0.060 typ 8x 1.52 0.100 typ 8x 2.54 0.100 typ 8x 2.54 0.300 7.62 figure 5. sop footprint (case 482) inch mm scale 2:1 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

3178 motorola sensor device data www.motorola.com/semiconductors 85 60 45 30 15 115 100 0 transfer function nominal transfer value: v out = v s (p x 0.007652 ) 0.92) +/ (pressure error x temp. factor x 0.007652 x v s ) v s = 5 v 0.25 vdc temperature error band temp multiplier 40 3 0 to 85 1 +125 3 temperature in c 4.0 3.0 2.0 0.0 1.0 40 20 0 20 40 60 140 120 100 80 mpxv4115v series temperature error factor pressure error band pressure in kpa (below atmospheric) pressure error (max) 1.950 1.725 1.500 1.500 1.725 1.950 pressure error (kpa) note: the temperature multiplier is a linear response from 0 to 40 c and from 85 to 125 c. 115 to 0 kpa 1.725 (kpa) 0 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3179 motorola sensor device data www.motorola.com/semiconductors $"$ "##%" # " ! $ !"$%" !#$ "$ the mpxv5004g series piezoresistive transducer is a stateoftheart monolithic silicon pressure sensor designed for a wide range of applications, but particularly those employing a microcontroller or microprocessor with a/d inputs. this sensor combines a highly sensitive implanted strain gauge with advanced micromachining techniques, thinfilm metallization, and bipolar processing to provide an accurate, high level analog output signal that is proportional to the applied pressure. features ? temperature compensated over 10 to 60 c ? available in gauge surface mount (smt) or through hole (dip) configurations ? durable thermoplastic (pps) package application examples ? washing machine water level ? ideally suited for microprocessor or microcontroller based systems figure 1. fully integrated pressure sensor schematic v s sensing element v out gnd thin film temperature compensation and gain stage #1 gain stage #2 and ground reference shift circuitry pins 1, 5, 6, 7, and 8 are no connects for small outline package device semiconductor technical data pin number 1 2 3 n/c v s gnd 5 6 7 n/c n/c n/c 4v out 8 n/c
integrated pressure sensor 0 to 3.92 kpa (0 to 400 mm h 2 o) 1.0 to 4.9 v output mpxv5004gc7u case 482c small outline package throughhole mpxv5004g7u case 482b j mpxv5004g6u case 482 mpxv5004gc6u case 482a note: pins 1, 5, 6, 7, and 8 are internal device connections. do not connect to external circuitry or ground. pin 1 is noted by the notch in the lead. small outline package surface mount mpxv5004dp case 1351 mpxv5004gvp case 1368 mpxv5004gp case 1369 rev 5 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

3180 motorola sensor device data www.motorola.com/semiconductors maximum ratings (note) parametrics symbol value unit maximum pressure (p1 > p2) p max 16 kpa storage temperature t stg 30 to +100 c operating temperature t a 0 to +85 c note: exposure beyond the specified limits may cause permanent damage or degradation to the device. operating characteristics (v s = 5.0 vdc, t a = 25 c unless otherwise noted, p1 > p2. decoupling circuit shown in figure 3 required to meet electrical specifications) characteristic symbol min typ max unit pressure range p op 0 e 3.92 400 kpa mm h 2 o supply voltage (1) v s 4.75 5.0 5.25 vdc supply current i s e e 10 madc span at 306 mm h 2 o (3 kpa) (2) v fss e 3.0 e v offset (3)(5) v off 0.75 1.00 1.25 v sensitivity v/p e 1.0 9.8 e v/kpa mv/mm h 2 o accuracy (4)(5) 0 to 100 mm h 2 o (10 to 60 c) 100 to 400 mm h 2 o (10 to 60 c) e e e 1.5 2.5 %v fss %v fss notes: 1. device is ratiometric within this specified excitation range. 2. span is defined as the algebraic difference between the output voltage at specified pressure and the output voltage at the mi nimum rated pressure. 3. offset (v off ) is defined as the output voltage at the minimum rated pressure. 4. accuracy (error budget) consists of the following: ? linearity: output deviation from a straight line relationship with pressure over the specified pressure range. ? temperature hysteresis: output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. ? pressure hysteresis: output deviation at any pressure within the specified range, when this pressure is cycled to and from the minimum or maximum rated pressure, at 25 c. ? offset stability: output deviation, after 1000 temperature cycles, 30 to 100 c, and 1.5 million pressure cycles, with minimum rated pressure applied. ? tcspan: output deviation over the temperature range of 10 to 60 c, relative to 25 c. ? tcoffset: output deviation with minimum rated pressure applied, over the temperature range of 10 to 60 c, relative to 25 c. ? variation from nominal: the variation from nominal values, for offset or full scale span, as a percent of v fss , at 25 c. 5. auto zero at factory installation: due to the sensitivity of the mpxv5004g, external mechanical stresses and mounting positio n can affect the zero pressure output reading. autozeroing is defined as storing the zero pressure output reading and subtracting this from the device's output during normal operations. reference an1636 for specific information. the specified accuracy assumes a maximum temperatur e change of 5 c between autozero and measurement. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

3181 motorola sensor device data www.motorola.com/semiconductors onchip temperature compensation, calibration and signal conditioning the performance over temperature is achieved by inte- grating the shearstress strain gauge, temperature com- pensation, calibration and signal conditioning circuitry onto a single monolithic chip. figure 2 illustrates the gauge configuration in the basic chip carrier (case 482). a fluorosilicone gel isolates the die surface and wire bonds from the environment, while allowing the pres- sure signal to be transmitted to the silicon diaphragm. the mpxv5004g series sensor operating characteristics are based on use of dry air as pressure media. media, other than dry air, may have adverse effects on sensor performance and longterm reliability. internal reliability and qualification test for dry air, and other media, are available from the factory. contact the factory for information regarding media tolerance in your application. figure 3 shows the recommended decoupling circuit for in- terfacing the output of the mpxv5004g to the a/d input of the microprocessor or microcontroller. proper decoupling of the power supply is recommended. figure 4 shows the sensor output signal relative to pres- sure input. typical, minimum and maximum output curves are shown for operation over a temperature range of 10 c to 60 c using the decoupling circuit shown in figure 3. the output will saturate outside of the specified pressure range. figure 2. crosssectional diagram (not to scale) 1.0 f ips 470 pf output vs 5 v 0.01 f gnd vout figure 3. recommended power supply decoupling and output filtering. for additional output filtering, please refer to application note an1646. fluorosilicone gel die coat wire bond differential sensing element thermoplastic case stainless steel cap lead frame p1 p2 die bond die figure 4. output versus pressure differential max differential pressure 5.0 4.0 3.0 2.0 output (v) transfer function: v out = v s *[(0.2*p) + 0.2] 1.5% v fss v s = 5.0 v 0.25 vdc temp = 10 to 60 c 1.0 min typical 2 kpa 200 mm h 2 o (see note 5 in operating characteristics) 4 kpa 400 mm h 2 o f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

3182 motorola sensor device data www.motorola.com/semiconductors pressure (p1)/vacuum (p2) side identification table motorola designates the two sides of the pressure sensor as the pressure (p1) side and the vacuum (p2) side. the pressure (p1) side is the side containing silicone gel which isolates the die from the environment. the motorola pressure sensor is designed to operate with positive differential pres- sure applied, p1 > p2. the pressure (p1) side may be identified by using the table below: part number case type pressure (p1) side identifier mpxv5004gc6u/t1 482a side with port attached mpxv5004g6u/t1 482 stainless steel cap mpxv5004gc7u 482c side with port attached mpxv5004g7u 482b stainless steel cap mpxv5004gp 1369 side with port attached mpxv5004dp 1351 side with port marking mpxv5004gvp 1368 stainless steel cap ordering information mpxv5004g series pressure sensors are available in the basic element package or with a pressure port. two packing options are offered for the surface mount configuration. device type / order no case no packing options device marking device type / order no . case no . packing options device marking mpxv5004g6u 482 rails mpxv5004g mpxv5004g6t1 482 tape and reel mpxv5004g mpxv5004gc6u 482a rails mpxv5004g mpxv5004gc6t1 482a tape and reel mpxv5004g mpxv5004gc7u 482c rails mpxv5004g mpxv5004g7u 482b rails mpxv5004g mpxv5004gp 1369 trays mpxv5004g mpxv5004dp 1351 trays mpxv5004g mpxv5004gvp 1368 trays mpxv5004g information for using the small outline package (case 482) minimum recommended footprint for surface mounted applications surface mount board layout is a critical portion of the total design. the footprint for the surface mount packages must be the correct size to ensure proper solder connection inter- face between the board and the package. with the correct fottprint, the packages will self align when subjected to a solder reflow process. it is always recommended to design boards with a solder mask layer to avoid bridging and short- ing between solder pads. 0.660 16.76 0.060 typ 8x 1.52 0.100 typ 8x 2.54 0.100 typ 8x 2.54 0.300 7.62 figure 5. sop footprint (case 482) inch mm scale 2:1 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3183 motorola sensor device data www.motorola.com/semiconductors !"$%" %"&
$"$ "##%" # " ! $ !"$%" !#$ "$ motorola's m pxv6115vc6u sensor integrates onc hip, bipolar op amp circuitry and thin film resistor networks to provide a high output signal and temperature compensation. the small form factor and high reliability of onchip integration make the motorola pressure sensor a logical and economical choice for the system designer. the mpxv6115vc6u piezoresistive transducer is a stateoftheart, monolithic, signal conditioned, silicon pressure sensor. this sensor combines advanced micromachining tec hniques, thin film metallization, and bipolar semi- conductor processing to provide an accurate, high level analog output signal that is proportional to applied pressure. figure 1 shows a block diagram of the internal circuitry integrated on a pressure sensor chip. features ? improved accuracy at high temperature ? 1.5% maximum error over 0 to 85 c ? ideally suited for microprocessor or microcontrollerbased systems ? temperature compensated from 40 to +125 c ? durable thermoplastic (pps) surface mount package application examples ? vacuum pump monitoring ? brake booster monitoring figure 1. fully integrated pressure sensor schematic v s sensing element v out gnd thin film temperature compensation and gain stage #1 gain stage #2 and ground reference shift circuitry pins 1, 5, 6, 7 and 8 are no connects semiconductor technical data 5 6 7 8 n/c v s gnd v out n/c n/c n/c integrated pressure sensor 115 to 0 kpa (16.7 to 2.2 psi) 0.2 to 4.6 volts output pin number note: pins 1, 5, 6, 7, and 8 are internal device connections. do not connect to external circuitry or ground. pin 1 is denoted by the notch in the lead. 1 2 3 mpxv6115vc6u case 482a 4 n/c small outline package rev 0 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3184 motorola sensor device data www.motorola.com/semiconductors maximum ratings (1) parametrics symbol value units maximum pressure (p1 p2) p max 400 kpa storage temperature t stg 40 to +125 c operating temperature t a 40 to +125 c output source current @ full scale output (2) i o + 0.5 madc output sink current @ minimum pressure offset (2) i o 0.5 madc notes: 1. exposure beyond the specified limits may cause permanent damage or degradation to the device. 2. maximum output current is controlled by effective impedance from v out to gnd or v out to v s in the application circuit. operating characteristics (v s = 5.0 vdc, t a = 25 c unless otherwise noted, p1 p2.) characteristic symbol min typ max unit pressure range p op 115 e 0 kpa supply voltage (1) v s 4.75 5.0 5.25 vdc supply current i o e 6.0 10 madc full scale output (2) (0 to 85 c) @ v s = 5.0 volts (p diff = 0 kpa) v fso 4.534 4.6 4.665 vdc full scale span (3) (0 to 85 c) @ v s = 5.0 volts v fss e 4.4 e vdc accuracy (4) (0 to 85 c) e e e 1.5 %v fss sensitivity v/p e 38.26 e mv/kpa response time (5) t r e 1.0 e ms warmup time (6) e e 20 e ms offset stability (7) e e 0.5 e %v fss notes: 1. device is ratiometric within this specified excitation range. 2. full scale output (v fso ) is defined as the output voltage at the maximum or full rated pressure. 3. full scale span (v fss ) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 4. accuracy is the deviation in actual output from nominal output over the entire pressure range and temperature range as a perc ent of span at 25 c due to all sources of error including the following: ? linearity: output deviation from a straight line relationship with pressure over the specified pressure range. ? temperature hysteresis: output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. ? pressure hysteresis: output deviation at any pressure within the specified range, when this pressure is cycled to and from minimum or maximum rated pressure at 25 c. ? tcspan: output deviation over the temperature range of 0 to 85 c, relative to 25 c. ? tcoffset: output deviation with minimum pressure applied, over the temperature range of 0 to 85 c, relative to 25 c. 5. response time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when s ubjected to a specified step change in pressure. 6. warmup time is defined as the time required for the product to meet the specified output voltage after the pressure has been stabilized. 7. offset stability is the product's output deviation when subjected to 1000 cycles of pulsed pressure, temperature cycling with bias test. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3185 motorola sensor device data www.motorola.com/semiconductors figure 2. cross sectional diagram sop (not to scale) figure 3. typical application circuit (output source current operation) v s pin 2 5.0 v gnd pin 3 v out pin 4 mpxv6115vc6u to adc 100 nf 51 k 47 pf fluoros i l i cone gel die coat wire bond differential sensing element thermoplastic case sta i nless steel cap lead frame p1 p2 die bond di e figure 2 illustrates the absolute sensing chip in the basic small outline chip carrier (case 482). figure 3 shows a typical application circuit (output source current operation). figure 4. output versus absolute pressure max transfer function: v out = v s *[(0.007652*p) + 0.92] (pressure error *temp factor*0.007652*v s ) v s = 5.0 v 0.25 vdc temp = 085 c min 115 95 75 55 35 15 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 v out vs. vacuum transfer function mpxv6115vc6u output (volts) 0 figure 4 shows the sensor output signal relative to pres- sure input. typical minimum and maximum output curves are shown for operation over 0 to 85 c temperature range. the output will saturate outside of the rated pressure range. a fluorosilicone gel isolates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the s ilicon diaphragm. the mpxv6115vc6u pressure sensor operating characteristics, internal reliability and qualification tests are based on use of dry air as the pressure media. media other than dry air may have adverse effects on sensor performance and longterm reliability. contact the factory for information regarding me- dia compatibility in your application. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3186 motorola sensor device data www.motorola.com/semiconductors transfer function (mpxv6115vc6u) nominal transfer value: v out = v s x (0.007652 x p + 0.92) (pressure error x temp. factor x 0.007652 x v s ) v s = 5.0 0.25 vdc temperature error band mpxv6115vc6u break points temp multiplier 40 3 0 to 85 1 125 2 temperature in c 4.0 3.0 2.0 0.0 1.0 40 20 0 20 40 60 140 120 100 80 temperature error factor note: the temperature multiplier is a linear response from 0 c to 40 c and from 85 c to 125 c pressure error band 85 60 45 30 15 115 100 0 pressure in kpa (below atmospheric) pressure error (max) 1.950 1.725 1.500 1.500 1.725 1.950 pressure error (kpa) 115 to 0 kpa 1.725 (kpa) 0 error limits for pressure ordering information e small outline package device type options case no. mpx series order no. packing options marking ported element vacuum, axial port 482a mpxv6115vc6u rails mpxv6115v f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3187 motorola sensor device data www.motorola.com/semiconductors surface mounting information minimum recommended footprint for small outline package surface mount board layout is a critical portion of the total design. the footprint for the semiconductor package must be the correct size to ensure proper solder connection inter- face between the board and the package. with the correct pad geometry, the packages will selfalign when subjected to a solder reflow process. it is always recommended to fabri- cate boards with a solder mask layer to avoid bridging and/or shorting between solder pads, especially on tight tolerances and/or tight layouts. 0.660 16.76 0.060 typ 8x 1.52 0.100 typ 8x 2.54 0.100 typ 2.54 0.300 7.62 figure 5. sop footprint (case 482a) inch mm f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3188 motorola sensor device data www.motorola.com/semiconductors ! !# !
" " prepared by: carl demington design engineering introduction this application note describes a technique to improve the linearity of motorola's mpx10 series (i.e., mpx10, mpxv10, and mpx12 pressure sensors) pressure transducers when they are interfaced to a microprocessor system. the linearization technique allows the user to obtain both high sensitivity and good linearity in a cost effective system. the mpx10, mpxv10 and mpx12 pressure transducers are semiconductor devices which give an electrical output signal proportional to the applied pressure over the pressure range of 010 kpa (075 mm hg). these devices use a unique transverse voltagediffused silicon straingauge which is sensitive to stress produced by pressure applied to a thin silicon diaphragm. one of the primary considerations when using a pressure transducer is the linearity of the transfer function, since this parameter has a direct effect on the total accuracy of the system, and compensating for nonlinearities with peripheral circuits is extremely complicated and expensive. the purpose of this document is to outline the causes of nonlinearity, the tradeoffs that can be made for increased system accuracy, and a relatively simple technique that can be utilized to maintain system performance, as well as system accuracy. origins of nonlinearity nonlinearity in semiconductor straingauges is a topic that has been the target of many experiments and much discussion. parameters such as resistor size and orientation, surface impurity levels, oxide passivation thickness and growth temperatures, diaphragm size and thickness are all contributors to nonlinear behavior in silicon pressure transducers. the motorola xducer was designed to minimize these effects. this goal was certainly accomplished in the mpx2000 series which have a maximum nonlinearity of 0.1% fs. however, to obtain the higher sensitivity of the mpx10 series, a maximum nonlinearity of 1% fs has to be allowed. the primary cause of the additional nonlinearity in the mpx10 series is due to the stress induced in the diaphragm by applied pressure being no longer linear. one of the basic assumptions in using semiconductor straingauges as pressure sensors is that the deflection of the diaphragm when pressure is applied is small compared to the thickness of the diaphragm. with devices that are very sensitive in the low pressure ranges, this assumption is no longer valid. the deflection of the diaphragm is a considerable percentage of the diaphragm thickness, especially in devices with higher sensitivities (thinner diaphragms). the resulting stresses do not vary linearly with applied pressure. this behavior can be reduced somewhat by increasing the area of the diaphragm and consequently thickening the diaphragm. due to the constraint, the device is required to have high sensitivity over a fairly small pressure range, and the nonlinearity cannot be eliminated. much care was given in the design of the mpx10 series to minimize the nonlinear behavior. however, for systems which require greater accuracy, external techniques must be used to account for this behavior. performance of an mpx device the output versus pressure of a typical mpx12 along with an endpoint straight line is shown in figure 1. all nonlinearity errors are referenced to the endpoint straight line (see data sheet). notice there is an appreciable deviation from the endpoint straight line at midscale pressure. this shape of curve is consistent with mpx10 and mpxv10, as well as mpx12 devices, with the differences between the parts being the magnitude of the deviation from the endpoint line. the major tradeoff that can be made in the total device performance is sensitivity versus linearity. figure 2 shows the relationship between full scale span and nonlinearity error for the mpx10 series of devices. the data shows the primary contribution to nonlinearity is nonproportional stress with pressure, while assembly and packaging stress (scatter of the data about the line) is fairly small and well controlled. it can be seen that relatively good accuracies (<0.5% fs) can be achieved at the expense of reduced sensitivity, and for high sensitivity the nonlinearity errors increase rapidly. the data shown in figure 2 was taken at room temperature with a constant voltage excitation of 3.0 volts.
semiconductor application note rev 3 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3189 motorola sensor device data www.motorola.com/semiconductors 90 80 70 60 50 40 30 20 10 0 90 80 70 60 50 40 30 20 10 0 pressure (t orr ) figure 1. mpx12 linearity analysis raw data v out (mv) 5.0 10 0 span (mv) figure 2. mpx10 series span versus linearity linearity (% fs) 4.0 3.0 2.0 1.0 0 1.0 90 80 70 60 50 40 30 20 compensation for nonlinearity the nonlinearity error shown in figure 1 arises from the assumption that the output voltage changes with respect to pressure in the following manner: v out =v off + sens*p [1] where v off = output voltage at zero pressure differential sens = sensitivity of the device p = applied pressure it is obvious that the true output does not follow this simple straight line equation. therefore, if an expression could be determined with additional higher order terms that more closely described the output behavior, increased accuracies would be possible. the output expression would then become v out = v off +(b 0 +b 1 *p+b 2 *p 2 +b 3 *p 3 +. . .) [2] where b 0 , b 1 , b 2 , b 3 , etc. are sensitivity coefficients. in order to determine the sensitivity coefficients given in equation [2] for the mpx10 series of pressure transducers, a polynomial regression analysis was performed on data taken from 139 devices with full scale spans ranging from 30 to 730 mv. it was found that second order terms are sufficient to give excellent agreement with experimental data. the calculated regression coefficients were typically 0.999999+ with the worst case being 0.99999. however, these sensitivity coefficients demonstrated a strong correlation with the full scale span of the device for which they were calculated. the correlation of b 0 , b 1 , and b 2 with full scale span is shown in figures 3 through 5. 0.5 25 span (mv) b 45 70 55 60 50 40 30 20 0.4 0.3 0.2 0.1 0 0.1 0.2 0.3 0.4 0.5 35 65 0 figure 3. mpx10 linearity analysis e correlation of b 0 v out = b 0 + b 1 (p) + b 2 (p) 2 b 0 = 0.1045 0.00295 * (span) 1.1 25 span (mv) b 45 70 55 60 50 40 30 20 35 65 1 figure 4. mpx10 linearity analysis e correlation of b 1 v out = b 0 + b 1 (p) + b 2 (p) 2 1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 b 1 = 0.2055 + 1.598e 3 * (span) + 1.723e 4 * (span) 2 0.0030 25 span (mv) b 45 70 55 60 50 40 30 20 35 65 2 figure 5. mpx10 linearity analysis e correlation of b 2 v out = b 0 + b 1 (p) + b 2 (p) 2 0.0025 0.0020 0.0015 0.0010 0.0005 b 2 = 1.293e 13 * (span) 5.68 in order to simplify the determination of these coefficients for the user, further regression analysis was performed so that expressions could be given for each coefficient as a function of full scale span. this would then allow the user to do a single pressure measurement, a series of calculations, and analytically arrive at the equation of the line that describes the output behavior of the transducer. nonlinearity errors were then calculated by comparing experimental data with the values calculated using equation [2] and the sensitivity coefficients given by the regression analysis. the resulting errors are shown in figures 6 through 9 at various pressure points. while using this technique has been successful in reducing the errors due to nonlinearity, the considerable spread and large number of devices that showed errors >1% indicate this technique was not as successful as desired. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3190 motorola sensor device data www.motorola.com/semiconductors figure 6. linearity error of general fit equation at 1/4 fs figure 7. linearity error of general fit equation at 1/2 fs 30 27 24 21 18 15 12 9.0 6.0 3.0 0.0 21.54 19.38 17.23 15.08 12.92 10.77 8.62 6.46 4.31 2.15 2.0 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 no. of units linearity error (% fs) general fit p = 1/4 fs average error = 0.15 standard deviation = 0.212 no. of units linearity error (% fs) general fit p = 1/2 fs average error = 0.02 standard deviation = 0.391 16.15 14.54 12.92 11.31 9.69 8.08 6.46 4.85 3.23 1.62 21 18 15 12 9.0 6.0 3.0 0.0 2.0 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 % % f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3191 motorola sensor device data www.motorola.com/semiconductors figure 8. linearity error of general fit equation at 3/4 fs figure 9. linearity error of general fit equation at fs 16.5 0.0 12.31 11.08 9.85 8.62 7.38 6.15 4.92 3.69 2.46 1.23 2.0 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 no. of units linearity error (% fs) general fit p = 3/4 fs average error = 0.10 standard deviation = 0.549 % 15 13.5 12 10.5 9.0 7.5 6.0 4.5 3.0 1.5 19.5 0.0 13.85 12.46 11.08 9.69 8.31 6.92 5.54 4.15 2.77 1.38 2.0 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 no. of units linearity error (% fs) general fit p = 1 fs average error = 0.11 standard deviation = 0.809 % 18 16.5 15 13.5 12 10.5 6.0 4.5 3.0 1.5 9.0 7.5 1.8 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3192 motorola sensor device data www.motorola.com/semiconductors a second technique that still uses a single pressure measurement as the input was investigated. in this method, the sensitivity coefficients are calculated using a piecewise linearization technique where the total span variation is divided into four windows of 10 mv (i.e., 3039.99, 4049.99, etc.) and coefficients calculated for each window. the errors that arise out of using this method are shown in figures 10 through 13. this method results in a large majority of the devices having errors <0.5%, while only one of the devices was >1%. the sensitivity coefficients that are substituted into equation [2] for the different techniques are given in table 1. it is important to note that for either technique the only measurement that is required by the user in order to clearly determine the sensitivity coefficients is the determination of the full scale span of the particular pressure transducer. figure 10. linearity error of piecewise linear fit at 1/4 fs 48 42 36 30 24 18 12 6.0 0.0 37.69 33.92 30.15 26.38 22.62 18.85 15.08 11.31 7.54 3.77 2.0 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 no. of units linearity error (% fs) general fit p = 1/4 fs average error = 0.18 standard deviation = 0.159 % 1.8 table 1. comparison of linearization methods span window b 0 b 1 b 2 general fit 0.1045 + 2.95e 3x 0.2055 + 1.598e 3x + 1.723e 4x 2 1.293e 13x 5.681 piecewise linear fit 3039.99 0.08209 2.246e 3x 0.02433 = 1.430e 2x 1.961e 4 + 8.816e 6x 4049.99 0.1803 4.67e 3x 0.119 + 1.655e 2x 1.572e 3 + 4.247e 5x 5059.99 0.1055 3.051e 3x 0.355 + 2.126e 2x 5.0813 3 + 1.116e 4x 6069.99 0.288 + 3.473e 3x 0.361 + 2.145e 2x 5.928e 3 + 1.259e 4x x = full scale span f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3193 motorola sensor device data www.motorola.com/semiconductors figure 11. linearity error of piecewise linear fit at 1/2 fs figure 12. linearity error of piecewise linear fit at 3/4 ps 27 24 21 18 15 12 9.0 6.0 0.0 20 18 16 14 12 10 8.0 6.0 4.0 2.0 2.0 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 no. of units linearity error (% fs) general fit p = 1/2 fs average error = 0.02 standard deviation = 0.267 % 1.8 3.0 21 18 15 12 9.0 6.0 0.0 16.15 14.54 12.92 11.31 9.69 8.08 6.46 4.85 3.23 1.62 2.0 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 no. of units linearity error (% fs) general fit p = 3/4 fs average error = 0.09 standard deviation = 0.257 % 1.8 3.0 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3194 motorola sensor device data www.motorola.com/semiconductors figure 13. linearity error of piecewise linear fit at fs 52.5 45 37.5 30 22.5 15 7.5 0.0 38.46 34.62 30.77 26.92 23.08 19.23 15.38 11.54 7.69 3.85 2.0 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 no. of units linearity error (% fs) general fit p = 1 fs average error = 0.13 standard deviation = 0.186 % 1.8 once the sensitivity coefficients have been determined, a system can then be built that provides an accurate output function with pressure. the system shown in figure 14 consists of a pressure transducer, a temperature compensation and amplification stage, an a/d converter, a microprocessor, and a display. the display block can be replaced with a control function if required. the a/d converter simply transforms the voltage signal to an input signal for the microprocessor, in which resides the lookup table of the transfer function generated from the previously determined sensitivity coefficients. the microprocessor can then drive a display or control circuit using standard techniques. summary while at first glance this technique appears to be fairly complicated, it can be a very cost effective method of building a highaccuracy, highsensitivity pressuremonitoring system for lowpressure ranges. figure 14. linearization system block diagram xducer temperature compensation and amplification microcontroller mc68hc908qt4 display f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3195 motorola sensor device data www.motorola.com/semiconductors
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" prepared by: randy frank motorola inc., semiconductor products sector phoenix, arizona introduction motorola's mpx series pressure sensors are silicon piezoresistive straingauges offered in a chipcarrier package (see figure 1). the exclusive chipcarrier package was developed to realize the advantages of highspeed, automated assembly and testing. in addition to high volume availability and low cost, the chipcarrier package offers users a number of packaging options. this application note describes several mounting techniques, offers lead forming recommendations, and suggests means of testing the mpx series of pressure sensors. figure 1. mpx pressure sensor in chip carrier package shown with port options differential port option case 344c01 figure 2. chip carrier and available ported packages basic element case 34415 suffix a / d gauge port case 344b01 suffix ap / gp gauge vacuum port case 344d01 suffix gvp dual port case 344c01 suffix dp axial port case 344f01 suffix asx / gsx axial vacuum port case 344g01 suffix gvsx stovepipe port case 344a01 suffix gvs stovepipe vacuum port case 344e01 suffix as/gs basic element case 86708 suffix a / d gauge port case 867b04 suffix ap / gp gauge vacuum port case 867d04 suffix gvp dual port case 867c05 suffix dp axial port case 867f03 suffix asx / gsx axial vacuum port case 867g03 suffix gvsx stovepipe port case 867e03 suffix as / gs stovepipe vacuum port case 867a04 suffix gvs
semiconductor application note rev 3 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3196 motorola sensor device data www.motorola.com/semiconductors port adapters available packages motorola's chipcarrier package and available ports for attachment of 1/8 i.d. hose are made from a high temperature thermoplastic that can withstand temperature extremes from 50 to 150 c (see figure 2). the port adapters were designed for rivet or 5/32 screw attachment to panels, printed circuit boards or chassis mounting. custom port adaptor installation techniques the motorola mpx silicon pressure sensor is available in a basic chip carrier cell which is adaptable for attachment to customer specific housings/ports (case 344 for 4pin devices and case 867 for 6pin devices). the basic cell has chamfered shoulders on both sides which will accept an oring such as parker seal's silicone oring (p/n#2015s46940). refer to figure 3 for the recommended oring to sensor cell interface dimensions. the sensor cell may also be glued directly to a custom housing or port using many commercial grade epoxies or rtv adhesives which adhere to grade valox 420, 30% glass reinforced polyester resin plastic or union carbide's udel ? polysulfone (mpx2300dt1 only). motorola recommends using thermoset ep530 epoxy or an equivalent. the epoxy should be dispensed in a continuous bead around the casetoport interface shoulder. refer to figure 4. care must be taken to avoid gaps or voids in the adhesive bead to help ensure that a complete seal is made when the cell is joined to the port. the recommended cure conditions for thermoset ep539 are 15 minutes at 150 c. after cure, a simple test for gross leaks should be performed to ensure the integrity of the cell to port bond. submerging the device in water for 5 seconds with full rated pressure applied to the port nozzle and checking for air bubbles will provide a good indication. testing mpx series pressure sensors pressure connection testing of pressure sensing elements in the chip carrier package can be performed easily by using a clamping fixture which has an oring seal to attach to the beveled surface. figure 8 shows a diagram of the fixture that motorola uses to apply pressure or vacuum to unported elements. when performing tests on packages with ports, a high durometer tubing is necessary to minimize leaks, especially in higher pressure range sensors. removal of tubing must be parallel to the port since large forces can be generated to the pressure port which can break the nozzle if applied at an angle. whether sensors are tested with or without ports, care must be exercised so that force is not applied to the back metal cap or offset errors can result. standard port attach connection motorola also offers standard port options designed to accept readily available silicone, vinyl, nylon or polyethylene tubing for the pressure connection. the inside dimension of the tubing selected should provide a snug fit over the port nozzle. installation and removal of tubing from the port nozzle must be parallel to the nozzle to avoid undue stress which may break the nozzle from the port base. whether sensors are used with motorola's standard ports or customer specific housings, care must be taken to ensure that force is uniformly distributed to the package or offset errors may be induced. figure 3. examples of motorola sensors in custom housings figure 4. case to port interface .114 .047 0 .125 .075 .037r 0 .021 .210 cell adhesive bead f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3197 motorola sensor device data www.motorola.com/semiconductors 3.40 0.134 2.39 0.094 1.27 0.050 2.21 2.13 0.087 0.084 14.48 0.570 16.23 0.639 a b f 0.36 (0.014) c m m m section ff 35 2 3.96 0.156 2.03 0.080 3 pl a b f 0.36 (0.014) c m m m 0.76 0.030 2.54 0.100 3.81 0.150 4.55 0.179 5.72 0.225 f 10.16 0.400 3.96 0.156 1.60 0.063 6.35 0.250 a b f 0.36 (0.014) c m m m 2 pl 13.66 13.51 0.538 0.532 a b c 0.36 (0.014) f 6.35 0.250 = diameter dimensions in mm inches zone d within zone d figure 5. port adapter dimensions figure 6. chipcarrier package figure 7. leadforming case 34415 all seals to be made on pressure sealing surface. top clamp area bottom clamp area leads should be securely clamped top and bottom in the area between the plastic body and the form being sure that no stress is being put on plastic body. the area between dotted lines represents surfaces to be clamped. style 1: pin 1. ground 2. + output 3. + supply 4. output m a m 0.136 (0.005) t 1234 pin 1 r n l g f d 4 pl seating plane t c m j b a dim min max min max millimeters inches a 0.595 0.630 15.11 16.00 b 0.514 0.534 13.06 13.56 c 0.200 0.220 5.08 5.59 d 0.016 0.020 0.41 0.51 f 0.048 0.064 1.22 1.63 g 0.100 bsc 2.54 bsc j 0.014 0.016 0.36 0.40 l 0.695 0.725 17.65 18.42 m 30 nom 30 nom n 0.475 0.495 12.07 12.57 r 0.430 0.450 10.92 11.43 notes: 1. dimensioning and tolerancing per asme y14.5m, 1994. 2. controlling dimension: inch. 3. dimension a is inclusive of the mold stop ring. mold stop ring not to exceed 16.00 (0.630). f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3198 motorola sensor device data www.motorola.com/semiconductors electrical connection the mpx series pressure sensor is designed to be installed on a printed circuit board (standard 0.100 lead spacing) or to accept an appropriate connector if installed on a baseplate. the leads of the sensor may be formed at right angles for assembly to the circuit board, but one must ensure that proper leadform techniques and tools are employed. hand or aneedlenoseo pliers should never be used for leadforming unless they are specifically designed for that purpose. refer to figure 7 for the recommended leadform technique. it is also important that once the leads are formed, they should not be straightened and reformed without expecting reduced durability. the recommended connector for offcircuit board applications may be supplied by jst corp. (18002924243) in mount prospect, il. the part numbers for the housing and pins are listed below. conclusion motorola's mpx series pressure sensors in the chip carrier package provide the design engineer several packaging alternatives. they can easily be tested with or without pressure ports using the information provided. connectors for chip carrier packages mfg./address/phone connector pin j.s. terminal corp. 4 pin housing: smp04vbc shf001t0.8ss 1200 business center dr. 6 pin housing: smp06vbc shf01t0.8ss mount prospect, il 60056 (800) 2924243 hand crimper yc12 recommended methode electronics, inc. 1300004 1400213 rolling meadows, il 60008 1402213 (312) 3923500 requires hand crimper 1402214 reel terminal blocks molex 22182043 2222 wellington court 22162041 lisle, il 60532 (312) 9694550 samtec ssw10402gsra p.o. box 1147 ssw10402gs new albany, in 47150 (812) 9446733 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3199 motorola sensor device data www.motorola.com/semiconductors a 0.002 total 0.0005 a a / 0.002 a 0.02 r 0.015 r 0.04 0.250 0.245 +0.003 0.000 0.525 0.60 1.00 1.25 ref 0.125 dia. for vacuum or pressure source for retaining ring (waldes kohinoor inc. truarc 510031) 30 0.01 x 45 4 pl 0.070 dia. 0.002 0.290 dia. 0.000 0.001 dia. 0.311 0.10 0.130 0.002 0.175 0.001 0.036 0.038 r 0.575 dia. 0.002 0.670 dia. 0.44 dia. 0.648 0.650 dia. 0.780 dia. for oring (parker seals 2015s46940) figure 8. oring test fixture f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3200 motorola sensor device data www.motorola.com/semiconductors !!
! ! " prepared by: jean claude hamelain motorola toulouse application lab manager introduction pressure is a very important parameter in most industrial applications such as air conditioning, liquid level sensing and flow control. in most cases, the sensor is located close to the measured source in a very noisy environment, far away from the receiver (recorder, computer, automatic controller, etc.) the transmission line can be as long as a few hundred meters and is subject to electromagnetic noise when the signal is transmitted as voltage. if the signal is transmitted as a current it is easier to recover at the receiving end and is less affected by the length of the transmission line. the purpose of this note is to describe a simple circuit which can achieve high performance, using standard motorola pressure sensors, operational amplifiers and discrete devices. performances the following performances have been achieved using an mpxv2102dp motorola pressure sensor and an mc33079 quad operational amplifier. the mpxv2102dp is a 100 kpa temperature compensated differential pressure sensor. the load is a 150 ohm resistor at the end of a 50 meter telephone line. the 15 volt power supply is connected at the receiver end. power supply +15 vdc, 30 ma connecting line 3 wire telephone cable load resistance 150 to 400 ohms temperature range 40 to + 85 c (up to +125 c with special hardware) pressure range 0 to 100 kpa total maximum error better than 2% full scale basic circuit the motorola mpxv2102dp pressure sensor is a very high performance piezoresistive pressure sensor. manufacturing technologies include standard bipolar processing techniques with state of the art metallization and onchip laser trim for offset and temperature compensation. this unique design, coupled with computer laser trimming, gives this device excellent performance at competitive cost for demanding applications such as automotive, industrial or healthcare. mc33078, 79 operational amplifiers are specially designed for very low input voltage, a high output voltage swing and very good stability versus temperature changes. first stage the motorola mpxv2102 and the operational amplifier are directly powered by the 15 vdc source. the first stage is a simple true differential amplifier made with both of the operational amplifiers in the mc33078. the potentiometer, r g , provides adjustment for the output. current generator the voltage to current conversion is made with a unity gain differential amplifier, one of the four operational amplifiers in an mc33079. the two output connections from the first stage are connected to the input of this amplifier through r3 and r5. good linearity is achieved by the matching between r3, r4, r5 and r6, providing a good common mode rejection. for the same reason, a good match between resistors r8 and r9 is needed. the mc33078 or mc33079 has a limited current output; therefore, a 2n2222 general purpose transistor is connected as the actual output current source to provide a 20 ma output. to achieve good performance with a very long transmission line it may be necessary to place some capacitors (c1, c2) between the power supply and output to prevent oscillations. calibration the circuit is electrically connected to the 15 vdc power supply and to the load resistor (receiver). the high pressure is connected to the pressure port and the low pressure (if using a differential pressure sensor), is connected to the vacuum port. it is important to perform the calibration with the actual transmission line connected. the circuit needs only two adjustments to achieve the 4 20 ma output current. 1. with no pressure (zero differential pressure), adjust r off to read exactly 4 ma on the receiver. 2. under the full scale pressure, adjust r g to exactly read 20 ma on the receiver. the calibration is now complete. semiconductor application note rev 2 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3201 motorola sensor device data www.motorola.com/semiconductors 4 2 3 6 figure 1. demo kit with 4 20 ma current loop r4 v cc = +15 volts dc c1 c2 r8 r9 r l r7 r6 r3 r5 r12 r10 r11 r off offset adjust a 3 2n2222 + + + + a 1 a 2 4 7 r2 r1 5 8 1 2 3 r g gain adj. 1 mpx2100dp output basic circuit of sek1 additional circuit for 4 to 20 ma current loop (receiver load resistance : r l = 150 to 400 ohms) r g = 47 k pot. r7 = 1 k r off = 1 m pot. r10 = 110 k * r1 = r2 = 330 k r11 = 1 m * r3 = r4 = 27 k r12 = 330 k * r5 = r6 = 27 k c1 = c2 = 0.1 m f * r8 = r9 = 150 a1, a2, a3 = 1/4 mc33079 * all resistor pairs must be matched at better than 0.5% note a: if using sek1 a1, a2, a3 = 1/2 mc33078 note a: r g from 20 k to 47 k note a: r1 and r2 from 1m to 330 k notice: the pressure sensor output is ratiometric to the power supply voltage. the output will change with the same ratio as voltage change. remote receiver the output is ratiometric to the power supply voltage. for example, if the receiver reads 18 ma at 80 kpa and 15 v power supply, the receiver should read 16.8 ma under the same pressure with 14 v power supply. for best results it is mandatory to use a regulated power supply. if that is not possible, the circuit must be modified by inserting a 12 v regulator to provide a constant supply to the pressure sensor. when using a motorola mc78l12ac voltage regulator, the circuit can be used with power voltage variation from 14 to 30 volts. the following results have been achieved using an mpx2100dp and two mc33078s. the resistors were regular carbon resistors, but pairs were matched at 0.3% and capacitors were 0.1 m f. the load was 150 ohms and the transmission line was a two pair telephone line with the +15 vdc power supply connected on the remote receiver side. note: best performances in temperature can be achieved using metal film resistors. the two potentiometers must be chosen for high temperatures up to 125 c. the complete circuit with pressure sensor is available under reference tza120 and can be ordered as a regular motorola product for evaluation. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3202 motorola sensor device data www.motorola.com/semiconductors + + + + + + + + + + 0 20 40 60 80 100 io (output ma) 3 4 5 6 7 8 9 10 13 12 11 14 15 16 17 18 19 20 21 22 figure 2. output versus pressure 85 pressure (kpa) power supply + 15 v dc, 150 ohm load +25 0 40 + + + + + + + + + figure 3. absolute error reference to algorithm reference algorithm io(ma) = 4 + 16 x p(kpa) pressure (kpa) 0 204060 80100 2.0 1.5 .5 0 .5 1.0 1.5 2.0 1.0 + error (kpa) reference algorithm is the straight from output at 255 0 pressure and output at full pressure 85 +25 0 40 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3203 motorola sensor device data www.motorola.com/semiconductors prepared by: michel burri, senior system engineer geneva, switzerland introduction the mpx2000 series pressure transducers are semiconductor devices which give an electrical output signal proportional to the applied pressure. the sensors are a single monolithic silicon diaphragm with strain gauge and thinfilm resistor networks on the chip. each chip is laser trimmed for full scale output, offset, and temperature compensation. the purpose of this document is to describe another method of measurement which should facilitate the life of the designer. the mpx2000 series sensors are available both as unported elements and as ported assemblies suitable for pressure, vacuum and differential pressure measurements in the range of 10 kpa through 200 kpa. the use of the onchip a/d converter of motorola's mc68hc05b6 hcmos mcu makes possible the design of an accurate and reliable pressure measurement system. system analysis the measurement system is made up of the pressure sensor, the amplifiers, and the mcu. each element in the chain has its own devicetodevice variations and temperature effects which should be analyzed separately. for instance, the 8bit a/d converter has a quantization error of about 0.2%. this error should be subtracted from the maximum error specified for the system to find the available error for the rest of elements in the chain. the mpx2000 series pressure sensors are designed to provide an output sensitivity of 4.0 mv/v excitation voltage with fullscale pressure applied or 20 mv at the excitation voltage of 5.0 vdc. an interesting property must be considered to define the configuration of the system: the ratiometric function of both the a/d converter and the pressure sensor device. the ratiometric function of these elements makes all voltage variations from the power supply rejected by the system. with this advantage, it is possible to design a chain of amplification where the signal is conditioned in a different way. + v s pin 3 rs1 r p pin 2 + pin 4 v out r in rs2 pin 1 gnd thermistor laser trimmed onchip figure 1. seven lasertrimmed resistors and two thermistors calibrate the sensor for offset, span, symmetry and temperature compensation ? ? ? ? ?? ?? ?? ?? ?? ?? ?? ?? ? ? ?? ?? the op amp configuration should have a good commonmode rejection ratio to cancel the dc component voltage of the pressure sensor element which is about half the excitation voltage value v s . also, the op amp configuration is important when the designer's objective is to minimize the calibration procedures which cost time and money and often don't allow the unittounit replacement of devices or modules. one other aspect is that most of the applications are not affected by inaccuracy in the region 0 kpa thru 40 kpa. therefore, the goal is to obtain an acceptable tolerance of the system from 40 kpa through 100 kpa, thus minimizing the inherent offset voltage of the pressure sensor.
semiconductor application note rev 1 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3204 motorola sensor device data www.motorola.com/semiconductors pressure sensor characteristics figure 2 shows the differential output voltage of the mpx2100 series at +25 c. the dispersion of the output voltage determines the best tolerance that the system may achieve without undertaking a calibration procedure, if any other elements or parameters in the chain do not introduce additional errors. v out (mv) v s = 5 vdc t a = 25 c p (kpa) fullscale 20 10 5 0 5 0 20 40 60 80 100 offset figure 2. spread of the output voltage versus the applied pressure at 25 c the effects of temperature on the full scale output and offset are shown in figure 3. it is interesting to notice that the offset variation is greater than the full scale output and both have a positive temperature coefficient respectively of +8.0 m v/degree and +5.0 m v excitation voltage. that means that the full scale variation may be compensated by modifying the gain somewhere in the chain amplifier by components arranged to produce a negative t c of 250 ppm/ c. the dark area of figure 3 shows the trend of the compensation which improves the full scale value over the temperature range. in the area of 40 kpa, the compensation acts in the ratio of 40/100 of the value of the offset temperature coefficient. figure 3. output voltage versus temperature. the dark area shows the trend of the compensation v out (f) d t positive full scale variation p (kpa) 0 20 40 60 80 100 offset variation 15 c +85 c op amp characteristics for systems with only one power supply, the instrument amplifier configuration shown in figure 4 is a good solution to monitor the output of a resistive transducer bridge. the instrument amplifier does provide an excellent cmrr and a symmetrical buffered high input impedance at both noninverting and inverting terminals. it minimizes the number of the external passive components used to set the gain of the amplifier. also, it is easy to compensate the temperature variation of the full scale output of the pressure sensor by implementing resistors ar f o having a negative coefficient temperature of 250 ppm/ c. the differentialmode voltage gain of the instrument amplifier is: avd = v1v2 vs2vs4 = 1 + 2 r f r g (1) +v s v1 v2 0 v + r f r g 2 4 figure 4. one power supply to excite the bridge and to develop a differential output voltage 3 1 + the major source of errors introduced by the op amp is offset voltages which may be positive or negative, and the input bias current which develops a drop voltage d v through the feedback resistance r f . when the op amp input is composed of pnp transistors, the whole characteristic of the transfer function is shifted below the dc component voltage value set by the pressure sensor as shown in figure 5. the gain of the instrument amplifier is calculated carefully to avoid a saturation of the output voltage, and to provide the maximum of differential output voltage available for the a/d converter. the maximum output swing voltage of the amplifiers is also dependent on the bias current which creates a d v voltage on the feedback resistance r f and on the full scale output voltage of the pressure sensor. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3205 motorola sensor device data www.motorola.com/semiconductors figure 5. instrument amplifier transfer function with spread of the device to device offset variation v1, v2 5 vdc 1/2 v cc v ee v cc v1 v2x v1x v2 vps (mv) 0 5 10 15 20 figure 5 shows the transfer function of different instrument amplifiers used in the same application. the same sort of random errors are generated by crossing the inputs of the instrument amplifier. the spread of the differential output voltage (v1v2) and (v2xv1x) is due to the unsigned voltage offset and its absolute value. figures 6 and 7 show the unittounit variations of both the offset and the bias current of the dual op amp mc33078. v io (mv) t ( c) +2 +1 0 1 2 50 25 0 25 50 75 100 125 figure 6. input offset voltage versus temperature unit 1 unit 2 unit 3 to realize such a system, the designer must provide a calibration procedure which is very time consuming. some extra potentiometers must be implemented for setting both the offset and the full scale output with a complex temperature compensation network circuit. the new proposed solution will reduce or eliminate any calibration procedure. figure 7. input bias current versus temperature l ib (na) t ( c) 600 450 300 150 0 50 25 0 25 50 75 100 125 unit 1 unit 2 mcu contribution as shown in figure 5, crossing the instrument amplifier inputs generated their mutual differences which can be computed by the mcu. 1 2 4 3 r g r f + + v1 v2 p 0 v figure 8. crossing of the instrument amplifier input using a port of the mcu +v s figure 8 shows the analog switches on the front of the instrument amplifier and the total symmetry of the chain. the residual resistance r ds(on) of the switches does not introduce errors due to the high input impedance of the instrument amplifier. with the aid of two analog switches, the mcu successively converts the output signals v1, v2. four conversions are necessary to compute the final result. first, two conversions of v1 and v2 are executed and stored in the registers r1, r2. then, the analog switches are commuted in the opposite position and the two last conversions of v2 x and v1x are executed and stored in the registers r2 x and r1x. then, the mcu computes the following equation: result = (r1 r2) + (r2x r1x) (2) f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3206 motorola sensor device data www.motorola.com/semiconductors the result is twice a differential conversion. as demonstrated below, all errors from the instrument amplifier are cancelled. other averaging techniques may be used to improve the result, but the appropriated algorithm is always determined by the maximum bandwidth of the input signal and the required accuracy of the system. 1 2 4 3 pressure sensor system mpx2100ap mc74hc4053 + 5 v i/o 0 v v1 r f r g r f v2 mc68hc05b6 ch1 p ch2 vrh v dd vrl v ss figure 9. two channel input and one output port are used by the mcu mc33078 + + system calculation sensor out 2 sensor out 4 vs2 = a (p) + of2 vs4 = b (p) + of4 amplifier out 1 amplifier out 2 v1 = avd (vs2 + of1) v2 = avd (vs4 + of2) inverting of the amplifier input v1x = avd (vs4 + of1) v2x = avd (vs2 + of2) delta = v1v2 1st differential result = avd * (vs2 of of1) avd * (vs4 + of2) deltax = v2xv1x 2nd differential result = avd * (vs2 + of2) vdc * (vs4 + of1) adding of the two differential results voutv = delta + deltax = avd*vs2 + avd*of2 + avd*of2 avd*of1 = 2 * avd * (vs2 vs4) = 2 * avd * [(a (p) + of2) (b (p) + of4)] = 2 * avd * [v(p) + voffset] + avd*of1 avd*of2 + avd*of2 avd*of1 there is a full cancellation of the amplifier offset of1 and of2. the addition of the two differential results v1v2 and v2xv1x produce a virtual output voltage voutv which becomes the applied input voltage to the a/d converter. the result of the conversion is expressed in the number of counts or bits by the ratiometric formula shown below: count = voutv * 255 vrhvrl 255 is the maximum number of counts provided by the a/d converter and vrhvrl is the reference voltage of the ratiometric a/d converter which is commonly tied to the 5.0 v supply voltage of the mcu. when the tolerance of the full scale pressure has to be in the range of 2.5%, the offset of the pressure sensor may be neglected. that means the system does not require any calibration procedure. the equation of the system transfer is then: count = 2 * avd * v(p) * 51/v where: avd is the differentialmode gain of the instrument amplifier which is calculated using the equation (1). then with r f = 510 k w and r g = 9.1 k w avd = 113 . the maximum counts available in the mcu register at the full scale pressure is: count (full scale) = 2 * 113 * 0.02 v * 51/v = 230 knowing that the mpx2100ap pressure sensor provides 20 mv at 5.0 excitation voltage and 100 kpa full scale pressure. the system resolution is 100 kpa/230 that give 0.43 kpa per count. mc68hc05b6 vrh ch1 p ch2 vrl v ss v dd + 5 v 0 v i/o fine cal. figure 10. full scale output calibration using the reference voltage vrhvrl f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3207 motorola sensor device data www.motorola.com/semiconductors when the tolerance of the system has to be in the range of 1%, the designer should provide only one calibration procedure which sets the full scale output (counts) at 25 c 100 kpa or under the local atmospheric pressure conditions. 1 2 4 3 pressure sensor system mpx2100ap mc74hc4053 mc33078 1/3 mc74hc4053 v1 v2 r f r g r f + 5 v 0 v i/o mc68hc05b6 p1 ch1 p2 vrl v ss vrh v dd + + figure 11. one channel input and two output ports are used by the mcu due to the high impedance input of the a/d converter of the mc68hc05b6 mcu, another configuration may be implemented which uses only one channel input as shown in figure 11. it is interesting to notice that practically any dual op amp may be used to do the job but a global consideration must be made to optimize the total cost of the system according the the requested specification. when the full scale pressure has to be sent with accuracy, the calibration procedure may be executed in different ways. for instance, the module may be calibrated directly using up/down push buttons. the gain of the chain is set by changing the vrh voltage of the ratiometric a/d converter with the r/2r ladder network circuit which is directly drived by the ports of the mcu. (see figure 12.) using a communication bus, the calibration procedure may be executed from a host computer. in both cases, the setting value is stored in the eerom of the mcu. the gain may be also set using a potentiometer in place of the resistor r f . but, this component is expensive, taking into account that it must be stable over the temperature range at long term. mc68hc05b6 vrh p3 p2 p1 ch1 ch2 v dd vrl v ss 2r ro r/2r ladder network 2r 2r 2r 2r r r r i/o + 5 v 0 v up down + 5 v figure 12. p0 bus table 1. pressure conversion table unity pa mbar torr atm at=kp/cm 2 mws psi 1 n/m 2 = 1 pascal 1 0.01 7.5 10 3 e e e e 1 mbar 100 1 0.75 e e 0.0102 0.014 1 torr = 1 mmhg 133.32 1.333 .1 e e e 0.019 1 atm (1) 101325 1013.2 760 1 1.033 10.33 14.69 1 at = 1 kp/cm 2 (2) 98066.5 981 735.6 0.97 1 10 14.22 1 m of water 9806.65 98.1 73.56 0.097 0.1 1 1.422 1 lb/sqin = 1 psi 6894.8 68.95 51.71 0.068 e e 1 (1) normal atmosphere (2) technical atmosphere f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3208 motorola sensor device data www.motorola.com/semiconductors
purpose this paper describes a simple method to gain more than 8bits of resolution with an 8bit a/d. the electronic design is relatively simple and uses standard components. principle consider a requirement to measure pressure up to 200 kpa. using a pressure sensor and an amplifier, this pressure can be converted to an analog voltage output. this analog voltage can then be converted to a digital value and used by the microprocessor as shown in figure 1. if we assume for this circuit that 200 kpa results in a +4.5 v output, the sensitivity of our system is:/ s 4.5 v 200kpa ( 1 ) 0.0225 v kpa or s 22.5 mv kpa if an 8bit a/d is used with 0 and 5 volt low and high references, respectively, then the resolution would be: s 5v 2 8 1 5v 255 ( 2 ) 0.01961 v or r v 19.60 mv per bit this corresponds to a pressure resolution of: r p 5v 19.60 mv bit ) 22.5 mv kpa ( 3 ) 0.871 kpa per bit assume a resolution of at least 0.1 kpa/bit is needed. this would require an a/d with at least 12 bits ( 2 12 = 4096 steps). one can artificially increase the a/d resolution as described below. refer to figure 1 and assume a pressure of 124 kpa is to be measured. with this system, the input signal to the a/d should read (assuming no offset voltage error): v m ( measured ) 4.5 ( papp ) x ( s )( 4 ) ( 124 kpa ) x 22.5 mv kpa 2790 mv, where papp is the pressure applied to the sensor. due to the resolution of the a/d, the microprocessor receives the following conversion: m ( 2790 mv ) 19.60 mv bit ( 5 ) 142.35 142 ( truncated to integer ) the calculated voltage for this stored value is: v c ( calculated ) ( 142 count ) x 19.60mv ( 6 ) count ) 2783 mv the microprocessor will output the stored value m to the d/a. the corresponding voltage at the analog output of the d/a, for an 8bit d/a with same references, will be 2783 mv. the calculated pressure corresponding to this voltage would be: p c ( calculated ) ( 2783 mv ) 22.5 mv kpa ( 7 ) 123.7 kpa thus, the error would be: e papppc ( 8 ) 124 kpa123.7 kpa 0.3 kpa this is greater than the 0.1 kpa resolution requirement. figure 1. block diagram +v g a/d mpu output circuitry vm m pc semiconductor application note rev 1 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3209 motorola sensor device data www.motorola.com/semiconductors a/d mpu +v g output circuitry g d/a figure 2. expanded block diagram vm vc d control c m m analog circuitry s figure 2 shows the block diagram of a system that can be used to reduce the inaccuracies caused by the limited a/d resolution. the microprocessor would use the stored value m, as described above, to cause a d/a to output the corresponding voltage, vc. vc is subtracted from the measured voltage, vm, using a differential amplifier, and the resulting voltage is amplified. assuming a gain, g, of 10 for the amplifier, the output would be: d ( vmvc ) g ( 9 ) ( 2790 mv2783 mv ) 10 70 mv the microprocessor will receive the following count from the a/d: c 70mv 19.60 mv count ( 10 ) 3.6 3 full counts the microprocessor then computes the actual pressure with the following equations: expanded voltage vc c r ) g )( 11 ) 2783 3 19.60 ) 10 ) 2789 mv, note: r is resolution of 8-bit d/a corresponding pressure 2789 mv ( 12 ) 22.5 mv kpa 123.9 kpa thus the error is: pressure error actual measured ( 13 ) 124 kpa 123.9 kpa 0.1 kpa figures 3 and 4 together provide a more detailed description of the analog portion of this system. +v r 3 r 2 r 5 r 8 r 9 r 10 a1 a2 + r 7 +v vm (to second stage) figure 3. first stage differential amplifier, offset adjust and gain adjust r 4 r 6 r 1 + note: r 7 = r 2 , r 1 = r 6 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3210 motorola sensor device data www.motorola.com/semiconductors vm (from first stage) r 11 r 15 r 17 a3 a4 vm r 12 r 13 r 14 r 16 d vc figure 4. second stage e difference amplifier and gain + + from d/a note: r 14 = r 12 , r 11 = r 13 first stage (figure 3) the first stage consists of the motorola pressure sensor; in this case the mpx2200 is used. this sensor typically gives a full scale span output of 40 mv at 200 kpa. the sensor output (v s ) is connected to the inputs of amplifier a1 (1/4 of the mc33079, a quad operational amplifier). the gain, g1, of this amplifier is r7/r6. the sensor has a typical zero pressure offset voltage of 1 mv. figure 3 shows offset compensation circuitry if it is needed. a1 output is fed to the noninverting input of a2 amplifier (1/4 of a mc33079) whose gain, g2, is 1+r 10 /r 9 . g2 should be set to yield 4.5 volts out with fullrated pressure. the second stage (figure 4) the output from a2 (vm = g1 x g2 x vs) is connected to the noninverting input of amplifier a3 (1/4 of a mc33079) and to the a/d where its corresponding (digital) value is stored by the microprocessor. the output of a3 is the amplified difference between vm, and the digitized/calculated voltage vc. amplifier a4 (1/4 of a mc33079) provides additional gain for an amplified difference output for the desired resolution. this difference output, d, is given by: d vm v c g3 g3 r14 r13 1 r17 r16 where g3 is the gain associated with amplifiers a3 and a4. the theoretical resolution is limited only by the accuracy of the programmable power supply. the motorola microprocessor used has an integrated a/d. the accuracy of this a/d is directly related to the reference voltage source stability, which can be selfcalibrated by the microprocessor. v expanded is the system output that is the sum of the voltage due to the count and the voltage due to the difference between the count voltage and the measured voltage. this is given by the following relation: v expanded v c d g3 therefore, pv expanded v expanded s. p expanded is the value of pressure (in units of kpa) that results from this improvedresolution system. this value can be output to a display or used for further processing in a control system. conclusion this circuit provides an easy way to have high resolution using inexpensive microprocessors and converters. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3211 motorola sensor device data www.motorola.com/semiconductors
! prepared by: denise williams discrete applications engineering introduction the two wire 4 20 ma current loop is one of the most widely utilized transmission signals for use with transducers in industrial applications. a two wire transmitter allows signal and power to be supplied on a single wirepair. because the information is transmitted as current, the signal is relatively immune to voltage drops from long runs and noise from motors, relays, switches and industrial equipment. the use of additional power sources is not desirable because the usefulness of this system is greatest when a signal has to be transmitted over a long distance with the sensor at a remote location. therefore, the 4 ma minimum current in the loop is the maximum usable current to power the entire control circuitry. figure 1 is a block diagram of a typical 4 20 ma current loop system which illustrates a simple two chip solution to converting pressure to a 4 20 ma signal. this system is designed to be powered with a 24 vdc supply. pressure is converted to a differential voltage by the motorola mpx5100 pressure sensor. the voltage signal proportional to the monitored pressure is then converted to the 4 20 ma current signal with the burrbrown xtr101 precision twowire transmitter. the current signal can be monitored by a meter in series with the supply or by measuring the voltage drop across r l . a key advantage to this system is that circuit performance is not affected by a long transmission line. ?? ?? ?? ?? ?? ?? ?? ?? sensor pressure port pressure source pressure sensor transmitter circuitry 4 20 ma pressure transducer transmission line r l current meter 24 vdc figure 1. system block diagram semiconductor application note rev 4 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3212 motorola sensor device data www.motorola.com/semiconductors input terminals a schematic of the 4 20 ma pressure transducer topology is shown in figure 2. connections to this topology are made at the terminals labeled (+) and (). because this system utilizes a current signal, the power supply, the load and any current meter must be put in series with the (+) to () terminals as indicated in the block diagram. the load for this type of system is typically a few hundred ohms. as described above, a typical use of a 4 20 ma current transmission signal is the transfer of information over long distances. therefore, a long transmission line can be connected between the (+) and () terminals on the evaluation board and the power supply/load. 2 14 d2 1n4565a 6.4v @ 0.5ma xdcr1 mpx7100 32 41 2 ma r3 39 r5 50 4 5 6 3 17 13 9 10 11 8 r1 750 1/2 w q1 mpsa06 u1 xtr101 12 r6 100k r4 1m r2 1k d1 1n4002 c1 0.01 m f + 4 20 ma output return figure 2. schematic diagram 4 20 ma pressure transducer pressure input the device supplied on this topology is an mpx5100dp, which provides two ports. p1, the positive pressure port, is on top of the sensor and p2, the vacuum port, is on the bottom of the sensor. the system can be supplied up to 15 psi of positive pressure to p1 or up to 15 psi of vacuum to p2 or a differential pressure up to 15 psi between p1 and p2. any of these pressure applications will create the same results at the sensor output. circuit description the xtr101 current transmitter provides two onemilliamp current sources for sensor excitation when its bias voltage is between 12 v and 40 v. the mpx5100 series sensors are constant voltage devices, so a zener, d2, is placed in parallel with the sensor input terminals. because the mpx5100 series parts have a high impedance the zener and sensor combination can be biased with just the two milliamps available from the xtr101. the offset adjustment is composed of r4 and r6. they are used to remove the offset voltage at the differential inputs to the xtr101. r6 is set so a zero input pressure will result in the desired output of 4 ma. r3 and r5 are used to provide the full scale current span of 16 ma. r5 is set such that a 15 psi input pressure results in the desired output of 20 ma. thus the current signal will span 16 ma from the zero pressure output of 4 ma to the full scale output of 20 ma. to calculate the resistor required to set the full scale output span, the input voltage span must be defined. the full scale output span of the sensor is 24.8 mv and is d v in to the xtr101. burrbrown specifies the following equation for r span . the 40 and 16 m w values are parameters of the xtr101. r span 40 16 ma vin ) 0.016 mhos ] 64 the xtr101 requires that the differential input voltage at pins 3 and 4, v2 v1 be less than 1v and that v2 (pin 4) always be greater than v1 (pin 3). furthermore, this differential voltage is required to have a common mode of 46 volts above the reference (pin 7). the sensor produces the differential output with a common mode of approximately 3.1 volts above its reference pin 1. because the current of both 1 ma sources will go through r2, a total common mode voltage of about 5.1 volts (1 k w x 2 ma + 3.1 volts = 5.1 volts) is provided. conclusion this circuit is an example of how the mpx5000 series sensors can be utilized in an industrial application. it provides a simple design alternative where remote pressure sensing is required. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3213 motorola sensor device data www.motorola.com/semiconductors table 1. parts list for 4 20 ma pressure transducer evaluation board designator quantity description rating manufacturer part number 1 1 4 4 2 2 pc board (see figure 3) input/output terminals 1/2 standoffs, nylon threaded 1/2 screws, nylon 5/8 screws, nylon 440 nuts, nylon motorola phx cont devb126 #1727010 c1 1 capacitor 0.01 m f 50 v d1 d2 1 1 diodes 100 v diode 6.4 v zener 1 a 1n4002 1n4565a q1 1 transistor npn bipolar motorola mpsa06 r1 r2 r3 r4 1 1 1 1 resistors, fixed 750 w 1 k w 39 w 1 m w 1/2 w r5 r6 1 1 resistors, variable 50 w , one turn 100 k w , one turn bourns bourns #3386p1500 #3386p1104 u1 1 integrated circuit two wire current transmitter burrbrown xtr101 xdcr1 1 sensor high impedance 15 psi motorola mpx5100dp note: all resistors are 1/4 w with a tolerance of 5% unless otherwise noted. all capacitors are 100 volt, ceramic capacitors w ith a tolerance of 10% unless otherwise noted. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3214 motorola sensor device data www.motorola.com/semiconductors ! ! prepared by: warren schultz discrete applications engineering introduction integrated semiconductor pressure sensors such as the mpx5100 greatly simplify electronic measurement of pressure. these devices translate pressure into a 0.5 to 4.5 volt output range that is designed to be directly compatible with microcomputer a/d inputs. the 0.5 to 4.5 volt range also facilitates interface with ics such as the lm3914, making bar graph pressure gauges relatively simple. a description of a bar graph pressure sensor evaluation board and its design considerations are presented here. figure 1. devb129 mpx5100 bar graph pressure gauge (board no longer available)
semiconductor application note rev 1 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3215 motorola sensor device data www.motorola.com/semiconductors evaluation board description a summary of the information required to use evaluation board number devb129 is presented as follows. a discussion of the design appears under the heading design considerations. function the evaluation board shown in figure 1 is designed to provide a 100 kpa full scale pressure measurement. it has two input ports. p1, the pressure port is on the top side of the mpx5100 sensor, and p2, a vacuum port, is on the bottom side. these ports can be supplied up to 100 kpa (15 psi)* of pressure on p1 or up to 100 kpa of vacuum on p2, or a differential pressure up to 100 kpa between p1 and p2. any of these sources will produce the same output. the primary output is a 10 segment led bar graph, which is labeled in increments of 10 kpa. if full scale pressure is adjusted for a value other than 100 kpa the bar graph may be read as a percent of full scale. an analog output is also provided. it nominally supplies 0.5 volts at zero pressure and 4.5 volts at 100 kpa. zero and full scale adjustments are made with potentiometers so labeled at the bottom of the board. both adjustments are independent of each other. electrical characteristics the following electrical characteristics are included to describe evaluation board operation. they are not specifications in the usual sense and are intended only as a guide to operation. characteristic symbol min typ max units power supply voltage b+ 6.8 e 13.2 volts full scale pressure p fs e e 100 kpa overpressure p max e e 700 kpa analog full scale v fs e 4.5 e volts analog zero pressure offset v off e 0.5 e volts analog sensitivity s aout e 40 e mv/kpa quiescent current i cc e 20 e ma full scale current i fs e 140 e ma content board contents are described in the following parts list, schematic, and silk screen plot. a pin by pin circuit description follows in the next section. pinbypin description b+: input power is supplied at the b+ terminal. minimum input voltage is 6.8 volts and maximum is 13.2 volts. the upper limit is based upon power dissipation in the lm3914 assuming all 10 led's are lit and ambient temperature is 25 c. the board will survive input transients up to 25 volts provided that power dissipation in the lm3914 does not exceed 1.3 watts. out: an analog output is supplied at the out terminal. the signal it provides is nominally 0.5 volts at zero pressure and 4.5 volts at 100 kpa. this output is capable of sourcing 100 m a at full scale output. gnd: there are two ground connections. the ground terminal on the left side of the board is intended for use as the power supply return. on the right side of the board, one of the test point terminals is also connected to ground. it provides a convenient place to connect instrumentation grounds. tp1: test point 1 is connected to the zero pressure reference voltage and can be used for zero pressure calibration. to calibrate for zero pressure, this voltage is adjusted with r6 to match the zero pressure voltage that is measured at the analog output (out) terminal. tp2: test point 2 performs a similar function at full scale. it is connected to the lm3914's reference voltage which sets the trip point for the uppermost led segment. this voltage is adjusted via r5 to set full scale pressure. p1, p2: pressure and vacuum ports p1 & p2 protrude from the mpx5100 sensor on the right side of the board. pressure port p1 is on the top and vacuum port p2 is on the bottom. neither is labeled. either one or a differential pressure applied to both can be used to obtain full scale readings up to 100 kpa (15 psi). maximum safe pressure is 700 kpa. * 100 kpa = 14.7 psi, 15 psi is used throughout the text for convenience f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3216 motorola sensor device data www.motorola.com/semiconductors design considerations in this type of an application the design challenge is how to interface a sensor with the bar graph output. mpx5100 sensors and lm3914 bar graph display drivers fit together so cleanly that having selected these two devices the rest of the design is quite straight forward. a block diagram that appears in figure 4 shows the lm3914's internal architecture. since the lower resistor in the input comparator chain is pinned out at r lo , it is a simple matter to tie this pin to a voltage that is approximately equal to the mpx5100's zero pressure output voltage. in figure 2, this is accomplished by dividing down the 5 volt regulator's output voltage through r1, r4, and adjustment pot r6. the voltage generated at the wiper of r6 is then fed into r lo which matches the sensor's zero pressure voltage and zeros the bar graph. the full scale measurement is set by adjusting the upper comparator's reference voltage to match the sensor's output at full pressure. an internal regulator on the lm3914 sets this voltage with the aid of resistors r2, r3, and adjustment pot r5 that are shown in figure 2. the mpx5100 requires 5 volt regulated power that is supplied by an mc78l05. the led's are powered directly from lm3914 outputs, which are set up as current sources. output current to each led is approximately 10 times the reference current that flows from pin 7 through r2, r5, and r3 to ground. in this design it is nominally (4.5 v/4.9k)10 = 9.2 ma. over a zero to 85 c temperature range accuracy for both the sensor and driver ic are 2.5%, totaling 5%. given a 10 segment display total accuracy is approximately (10 kpa +5%). conclusion perhaps the most noteworthy aspect to the bar graph pressure gauge described here is how easy it is to design. the interface between an mpx5100 sensor, lm3914 display driver, and bar graph output is direct and straight forward. the result is a simple circuit that is capable of measuring pressure, vacuum, or differential pressure; and will also send an analog signal to other control circuitry. figure 2. mpx5100 pressure gauge s1 on/off 1 2 3 4 5 6 7 8 9 18 17 16 15 14 13 12 11 10 led led gnd b+ rlo sig rhi ref adj mod u1 u1 lm3914 tp2 (full scale calibration) tp1 (zero calibration) gnd full scale calibration d1 d2 d3 d4 d5 d6 d7 d8 d9 d10 r2 1.2 k r5 1 k r3 2.7 k r1 100 r6 100 u2 mpx5100 1 2 3 1 2 3 i g o gnd analog out +12 v c1 0.1 m f c2 1 m f u3 mc78l05acp zero cal. r4 1.3k led led led led led led led led f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3217 motorola sensor device data www.motorola.com/semiconductors figure 3. silk screen 2x u3 r3 r2 r5 r6 full scale devb129 on off b+ out gnd tp1 tp2 gnd c1 c2 mpx5100 kpa 100 90 80 70 60 50 40 30 20 10 pressure mv57164 lm3914 motorola discrete applications mpx5100 pressure gauge zero table 1. parts list designators quant. description rating manufacturer part number c1 c2 1 1 ceramic cap ceramic cap 0.1 m f 1 m f d1d10 1 bar graph led gi mv57164 r1 r2 r3 r4 r5 r6 1 1 1 1 1 1 1/4 w film resistor 1/4 w film resistor 1/4 w film resistor 1/4 w film resistor trimpot trimpot 100 1.2k 2.7k 1.3k 1k 100 bourns bourns s1 1 on/off switch nkk 12sdp2 u1 u2 u3 1 1 1 bar graph ic pressure sensor voltage regulator national motorola motorola lm3914 mpx5100 mc78l05acp e e e e 1 3 4 4 terminal block test point terminal nylon spacer 440 nylon screw 3/8 1/4 augat components corp. 25v03 tp1040104 note: all resistors have a tolerance of 5% unless otherwise noted. note: all capacitors are 50 volt ceramic capacitors with a tolerance of 10% unless otherwise noted. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3218 motorola sensor device data www.motorola.com/semiconductors figure 4. lm3914 block diagram reference voltage source 1.25 v mode select amplifier + buffer ref out this load determines led brightness controls type of display, bar or single led comparator 1 of 10 lm3914 10 11 12 13 14 15 16 17 18 1 1 k 1 k 1 k 1 k 1 k 1 k 1 k 1 k 1 k 1 k led v + r hi 6 7 8 3 4 5 r lo ref adj v + sig in v 9 2 from pin 11 v + 20 k + + + + + + + + + + + f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3219 motorola sensor device data www.motorola.com/semiconductors "! $ ! # prepared by: bill lucas discrete applications engineering introduction interfacing pressure sensors to analogtodigital converters or microprocessors with onchip a/d converters has been a challenge that most engineers do not enjoy accepting. recent design advances in pressure sensing technology have allowed the engineer to directly interface a pressure sensor to an a/d converter with no additional active components. this has been made possible by integrating a temperature compensated pressure sensor element and active linear circuitry on the same die. a description of an evaluation board that shows the ease of interfacing a signal conditioned pressure sensor to an a/d converter is presented here. figure 1. devb114 mpx5100 evaluation module (board no longer available)
semiconductor application note rev 1 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3220 motorola sensor device data www.motorola.com/semiconductors purpose this evaluation system, shown in figure 1, demonstrates the ease of operation and interfacing of the motorola mpx5100 series pressure sensors with onchip temperature compensation, calibration and amplification. the board may be used to evaluate the sensor's suitability for a specific application. description the devb114 evaluation board is constructed on a small printed circuit board. it is powered from a single +5 vdc regulated power supply. the system will display the pressure applied to the mpx5100 sensor in pounds per square inch. the range is 0 psi through 15 psi, resolved to 0.1 psi. no potentiometers are used in the system to adjust the span and offset. the sensor's zero offset voltage with no pressure applied to the sensor is empirically computed each time power is applied to the system and stored in ram. the sensitivity of the mpx5100 is repeatable from unit to unit. there is a facility for a small arubberingo of the slope constant built into the program. it is accomplished with jumpers j1 and j2, and is explained in the operation section. the board contents are further described in the schematic, silk screen plot, and parts list that appear in figures 2, 3 and table 1. basic circuit the evaluation board consists of three basic subsystems: an mpx5100gp pressure sensor, a four digit liquid crystal display (only three digits and a decimal are used) and a programmed microprocessor with the necessary external circuitry to support the operation of the microprocessor. 30 29 28 27 26 25 24 31 38 37 36 35 34 33 32 48 45 44 42 43 46 47 49 44 v ss ~ .302 v ~ 4.85 v 15 ohm 453 ohm 22 pf 100 m f 52 50 td0 rdi 5 porta portb 3 4 5 6 7 1 2 0 3 4 5 6 7 1 2 76 543 21 0 portc gnd vpp6 15 1% 1% 1% 30.1 ohm xdcr1 reset in u1 u2 34064p 5 .1 + 10k 10k 4.7k 22 pf 10meg 4 mhz y1 c4 c3 c2 c1 r7 r6 r5 r4 r3 r2 r1 j3 mc68hc705b5fn +5 out v cc mpx5100 tcap2 tcap1 d/a pd5 pd0 pd1 pd2 pd3 pd4 v dd +5 pd7 pd6 17 16 osc2 osc1 +5 8 7 v rh v rl +5 gnd +5 18 reset irq 19 43 j2 j1 +5 14, 33 39, 38, 40 28 bp iee part number lcd5657 or equal liquid crystal display 26 37 36 35 34 32 31 30 29 27 25 24 23 22 21 20 19 14 12 11 17 18 16 15 13 10 9 8 7 6 5 14 13 12 11 10 9212223 lc d figure 2. devb114 system schematic ___ ______ f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3221 motorola sensor device data www.motorola.com/semiconductors table 1. devb114 parts list designators quant. description rating manufacturer part number c1 1 100 m f electrolytic capacitor 25 vdc sprague 513d107m025bb4 c2 1 0.1 m f ceramic capacitor 50 vdc sprague 1c105z5u104m050b c3, c4 2 22 pf ceramic capacitor 100 vdc mepco/centralab cn15a220k j1, j2 1 dual row straight .025 pins arranged on .1 grid molex 10891043 lcd 1 liquid crystal display amperex ltd226r12 r1 1 4.7 k ohm resistor r2 1 10 meg ohm resistor r3, r4 2 10 k ohm resistor r5 1 15 ohm 1% 1/4 w resistor r6 1 453 ohm 1% 1/4 w resistor r7 1 30.1 ohm 1% 1/4 w resistor xdcr1 1 pressure sensor motorola mpx5100gp u1 1 microprocessor motorola mc68hc705b5fn or motorola xc68hc705b5fn u2 1 under voltage detector motorola mc34064p5 y1 1 crystal (low profile) 4.0 mhz ecs ecs40s4 no designator 1 52 pin plcc socket amp 8215751 no designator 2 jumpers for j1 and j2 molex 15291025 no designator 1 bare printed circuit board note: all resistors are 1/4 w resistors with a tolerance of 5% unless otherwise noted. note: all capacitors are 100 volt, ceramic capacitors with a tolerance of 10% unless otherwise noted. figure 3. silk screen devb114 rev. 0 gnd +5 j3 r3 r4 r5 r6 r7 j1 j2 r1 u2 tp1 v cc 1 r2 y1 c4 c3 c2 c1 xdrc1 lcd1 u1 xdrc out gnd tp3 tp2 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3222 motorola sensor device data www.motorola.com/semiconductors theory of operation referring to the schematic, figure 2, the mpx5100 pressure sensor is connected to port d bit 5 of the microprocessor. this port is an input to the onchip 8 bit analog to digital converter. the pressure sensor provides a signal output to the microprocessor of approximately 0.5 vdc at 0 psi to 4.5 vdc at 15 psi of applied pressure as shown in figure 4. the input range of the a to d converter is set at approximately 0.3 vdc to 4.85 vdc. this compresses the range of the a to d converter around the output range of the sensor to maximize the a to d converter resolution; 0 to 255 counts is the range of the a to d converter. v rh and v rl are the reference voltage inputs to the a to d converter. the resolution is defined by the following: analogtodigital converter count = [(v xdcr v rl )/(v rh v rl )] ? 255 the count at 0 psi = [(.5 .302)/(4.85 .302)] ? 255 11 the count at 15 psi = [(4.5 .302)/(4.85 .302)] ? 255 235 therefore the resolution = count @ 15 psi count @ 0 psi or the resolution is (235 11) = 224 counts. this translates to a system that will resolve to 0.1 psi. min typ max output (vdc) kpa psi 4.5 0.5 0 0 25 50 75 100 3.62 7.25 10.87 14.5 typ span typ offset v s = 5.0 vdc t a =25 c mpx5100 figure 4. mpx5100 output versus pressure input the voltage divider consisting of r5 through r7 is connected to the +5 volts powering the system. the output of the pressure sensor is ratiometric to the voltage applied to it. the pressure sensor and the voltage divider are connected to a common supply; this yields a system that is ratiometric. by nature of this ratiometric system, variations in the voltage of the power supplied to the system will have no effect on the system accuracy. the liquid crystal display is directly driven from i/o ports a, b, and c on the microprocessor. the operation of a liquid crystal display requires that the data and backplane pins must be driven by an alternating signal. this function is provided by a software routine that toggles the data and backplane at approximately a 30 hz rate. the microprocessor section of the system requires certain support hardware to allow it to function. the mc34064p5 (u2) provides an under voltage sense function which is used to reset the microprocessor at system powerup. the 4 mhz crystal (y1) provides the external portion of the oscillator function for clocking the microprocessor and provides a stable base for time based functions. jumpers j1 and j2 are examined by the software and are used to arubbero the slope constant. operation the system must be connected to a 5 vdc regulated power supply. note the polarity marked on the power terminal j3. jumpers j1 and j2 must either both be installed or both be removed for the normal slope constant to be used. the pressure port on the mpx5100 sensor must be left open to atmosphere anytime the board is poweredup. as previously stated, the sensor's voltage offset with zero pressure applied is computed at powerup. you will need to apply power to the system. the lcd will display cal for approximately 5 seconds. after that time, the lcd will then start displaying pressure. to improve upon the accuracy of the system, you can change the constant used by the program that constitutes the span of the sensor. you will need an accurate test gauge to measure the pressure applied to the sensor. anytime after the display has completed the zero calculation (after cal is no longer displayed), apply 15.0 psi to the sensor. make sure that jumpers j1 and j2 are either both installed or both removed. referring to table 2, you can increase the displayed value by installing j1 and removing j2. conversely, you can decrease the displayed value by installing j2 and removing j1. j1 j2 action in out out in in out in out use normal span constant use normal span constant decrease span constant approximately 1.5% increase span constant approximately 1.5% table 2. software the source code, compiler listing, and srecord output for the software used in this system are available on the motorola freeware bulletin board service in the mcu directory under the filename devb114.arc. to access the bulletin board you must have a telephone line, a 300, 1200 or 2400 baud modem and a terminal or personal computer. the modem must be compatible with the bell 212a standard. call 15128913733 to access the bulletin board service. the software for the system consists of several modules. their functions provide the capability for system calibration as well as displaying the pressure input to the mpx5100 transducer. figure 5 is a flowchart for the program that controls the system. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3223 motorola sensor device data www.motorola.com/semiconductors figure 5. devb114 software flowchart yes start no initialize display i/o ports initialize timer registers allow interrupts perform auto zero timer interrupt j1 out? accumulate 100 a/d conversions compute input pressure convert to decimal place in result output buffer service timer registers setup counter for next interrupt service liquid crystal display return from interrupt slope = 64 slope = 63 j2 out? no slope = 65 yes the compiler used in this project was provided by byte craft ltd. (519) 8886911. a compiler listing of the program is included at the end of this document. the following is a brief explanation of the routines: delay() used to provide approximately a 20 ms loop. read_a2d() performs one hundred reads on the analog to digital converter on multiplexer channel 5 and returns the accumulation. fixcompare() services the internal timer for 30 ms timer compare interrupts. timercmp() alternates the data and backplane for the liquid crystal display. initio() sets up the microcomputer's i/o ports, timer, allows processor interrupts, and calls adzero(). adzero() this routine is necessary at powerup time because it delays the power supply and allows the transducer to stabilize. it then calls `read_atod()' and saves the returned value as the sensors output voltage with zero pressure applied. cvt_bin_dec(unsigned long arg) this routine converts the unsigned binary argument passed in `arg' to a five digit decimal number in an array called `digit'. it then uses the decimal results for each digit as an index into a table that converts the decimal number into a segment pattern for the display. it is then output to the display. display_psi() this routine is called from `main()'. the ana- log to digital converter routine is called, the pressure is calculated, and the pressure applied to the sensor is dis- played. the loop then repeats. main() this is the main routine called from reset. it calls `initio()' to set up the system's i/o. `display_psi()' is called to compute and display the pressure applied to the sensor. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3224 motorola sensor device data www.motorola.com/semiconductors software source/assembly program code #pragma option v ; /* rev 1.1 code rewritten to use the mc68hc705b5 instead of the mc68hc805b6. wll 6/17/91 the following 'c' source code is written for the devb114 demonstration board. it was compiled with a compiler courtesy of: byte craft ltd. 421 king st. waterloo, ontario canada n2j 4e4 (519)8886911 some source code changes may be necessary for compilation with other compilers. bill lucas 8/5/90 motorola, sps */ 0800 1700 #pragma memory romprog [5888] @ 0x0800 ; 0050 0096 #pragma memory rampage0 [150] @ 0x0050 ; /* vector assignments */ 1ffe #pragma vector __reset @ 0x1ffe ; 1ffc #pragma vector __swi @ 0x1ffc ; 1ffa #pragma vector irq @ 0x1ffa ; 1ff8 #pragma vector timercap @ 0x1ff8 ; 1ff6 #pragma vector timercmp @ 0x1ff6 ; 1ff4 #pragma vector timerov @ 0x1ff4 ; 1ff2 #pragma vector sci @ 0x1ff2 ; #pragma has stop ; #pragma has wait ; #pragma has mul ; /* register assignments for the 68hc705b5 microcontroller */ 0000 #pragma portrw porta @ 0x00; /* */ 0001 #pragma portrw portb @ 0x01; /* */ 0002 #pragma portrw portc @ 0x02; /* */ 0003 #pragma portrw portd @ 0x03; /* in , ,ss ,sck ,mosi,miso,txd,rxd */ 0004 #pragma portrw ddra @ 0x04; /* data direction, port a */ 0005 #pragma portrw ddrb @ 0x05; /* data direction, port b */ 0006 #pragma portrw ddrc @ 0x06; /* data direction, port c (all output) */ 0007 #pragma portrw eeclk @ 0x07; /* eeprom/eclk cntl */ 0008 #pragma portrw addata @ 0x08; /* a/d data register */ 0009 #pragma portrw adstat @ 0x09; /* a/d stat/control */ 000a #pragma portrw plma @ 0x0a; /* pulse length modulation a */ 000b #pragma portrw plmb @ 0x0b; /* pulse length modulation b */ 000c #pragma portrw misc @ 0x0c; /* miscellaneous register */ 000d #pragma portrw scibaud @ 0x0d; /* sci baud rate register */ 000e #pragma portrw scicntl1 @ 0x0e; /* sci control 1 */ 000f #pragma portrw scicntl2 @ 0x0f; /* sci control 2 */ 0010 #pragma portrw scistat @ 0x10; /* sci status reg */ f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3225 motorola sensor device data www.motorola.com/semiconductors 0011 #pragma portrw scidata @ 0x11; /* sci data */ 0012 #pragma portrw tcr @ 0x12; /* icie,ocie,toie,0;0,0,iege,olvl */ 0013 #pragma portrw tsr @ 0x13; /* icf,ocf,tof,0; 0,0,0,0 */ 0014 #pragma portrw icaphi1 @ 0x14; /* input capture reg (hi0x14, lo0x15) */ 0015 #pragma portrw icaplo1 @ 0x15; /* input capture reg (hi0x14, lo0x15) */ 0016 #pragma portrw ocmphi1 @ 0x16; /* output compare reg (hi0x16, lo0x17)*/ 0017 #pragma portrw ocmplo1 @ 0x17; /* output compare reg (hi0x16, lo0x17)*/ 0018 #pragma portrw tcnthi @ 0x18; /* timer count reg (hi0x18, lo0x19) */ 0019 #pragma portrw tcntlo @ 0x19; /* timer count reg (hi0x18, lo0x19) */ 001a #pragma portrw acnthi @ 0x1a; /* alternate count reg (hi$1a, lo$1b) */ 001b #pragma portrw acntlo @ 0x1b; /* alternate count reg (hi$1a, lo$1b) */ 001c #pragma portrw icaphi2 @ 0x1c; /* input capture reg (hi0x1c, lo0x1d) */ 001d #pragma portrw icaplo2 @ 0x1d; /* input capture reg (hi0x1c, lo0x1d) */ 001e #pragma portrw ocmphi2 @ 0x1e; /* output compare reg (hi0x1e, lo0x1f)*/ 001f #pragma portrw ocmplo2 @ 0x1f; /* output compare reg (hi0x1e, lo0x1f)*/ /* put constants and variables here...they must be global */ /***********************************************************************/ 1efe 74 #pragma mor @ 0x1efe = 0x74; /* this disables the watchdog counter and does not add pulldown resistors on ports b and c */ 0800 fc 30 da 7a 36 6e e6 38 fe const char lcdtab[]={0xfc,0x30,0xda,0x7a,0x36,0x6e,0xe6,0x38,0xfe,0x3e }; 0809 3e /* lcd pattern table 0 1 2 3 4 5 6 7 8 9 */ 080a 27 10 03 e8 00 64 00 0a const long dectable[] = { 10000, 1000, 100, 10 }; 0050 0005 unsigned int digit[5]; /* buffer to hold results from cvt_bin_dec functio */ 0000 registera ac; /* processor's a register */ 0055 long atodtemp; /* temp to accumulate 100 a/d readings for smoothing */ 0059 long slope; /* multiplier for adc to engineering units conversion */ 005b int adcnt; /* a/d converter loop counter */ 005c long xdcr_offset; /* initial xdcr offset */ 005e 0060 unsigned long i,j; /* counter for loops */ 0062 int k; /* misc variable */ struct bothbytes { int hi; int lo; }; union isboth { long l; struct bothbytes b; }; 0063 0002 union isboth q; /* used for timer setup */ f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3226 motorola sensor device data www.motorola.com/semiconductors /**************************************************************************/ /* code starts here */ /**************************************************************************/ /* these interrupts are not used...give them a graceful return if for some reason one occurs */ 1ffc 08 12 __swi(){} 0812 80 rti 1ffa 08 13 irq(){} 0813 80 rti 1ff8 08 14 timercap(){} 0814 80 rti 1ff4 08 15 timerov(){} 0815 80 rti 1ff2 08 16 sci(){} 0816 80 rti /**************************************************************************/ void delay(void) /* just hang around for a while */ { 0817 4f clra for (i=0; i<20000; ++i); 0818 3f 57 clr $57 081a b7 58 sta $58 081c b6 57 lda $57 081e b7 5e sta $5e 0820 b6 58 lda $58 0822 b7 5f sta $5f 0824 b6 5f lda $5f 0826 a0 20 sub #$20 0828 b6 5e lda $5e 082a a2 4e sbc #$4e 082c 24 08 bcc $0836 082e 3c 5f inc $5f 0830 26 02 bne $0834 0832 3c 5e inc $5e 0834 20 ee bra $0824 0836 81 rts } /**************************************************************************/ read_a2d(void) { /* read the a/d converter on channel 5 and accumulate the result in atodtemp */ 0837 3f 56 clr $56 atodtemp=0; /* zero for accumulation */ 0839 3f 55 clr $55 083b 4f clra for ( adcnt = 0 ; adcnt<100; ++adcnt) /* do 100 a/d conversions */ 083c b7 5b sta $5b 083e b6 5b lda $5b 0840 a8 80 eor #$80 0842 a1 e4 cmp #$e4 0844 24 21 bcc $0867 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3227 motorola sensor device data www.motorola.com/semiconductors { 0846 a6 25 lda #$25 adstat = 0x25; /* convert on channel 5 */ 0848 b7 09 sta $09 084a 0f 09 fd brclr 7,$09,$084a while (!(adstat & 0x80)); /* wait for a/d to complete */ 084d b6 08 lda $08 atodtemp = addata + atodtemp; 084f 3f 57 clr $57 0851 b7 58 sta $58 0853 bb 56 add $56 0855 b7 58 sta $58 0857 b6 57 lda $57 0859 b9 55 adc $55 085b b7 57 sta $57 085d b7 55 sta $55 085f b6 58 lda $58 0861 b7 56 sta $56 } 0863 3c 5b inc $5b 0865 20 d7 bra $083e 0867 b6 56 lda $56 atodtemp = atodtemp/100; 0869 b7 58 sta $58 086b b6 55 lda $55 086d b7 57 sta $57 086f 3f 66 clr $66 0871 a6 64 lda #$64 0873 b7 67 sta $67 0875 cd 0a 5e jsr $0a5e 0878 cd 0a 8f jsr $0a8f 087b bf 55 stx $55 087d b7 56 sta $56 087f 81 rts return atodtemp; } /**************************************************************************/ void fixcompare (void) /* setsup the timer compare for the next interrup */ { 0880 b6 18 lda $18 q.b.hi =tcnthi; 0882 b7 63 sta $63 0884 b6 19 lda $19 q.b.lo = tcntlo; 0886 b7 64 sta $64 0888 ab 4c add #$4c q.l +=7500; /* ((4mhz xtal/2)/4) = counter period = 2us.*7500 = 15ms.*/ 088a b7 64 sta $64 088c b6 63 lda $63 088e a9 1d adc #$1d 0890 b7 63 sta $63 0892 b7 16 sta $16 ocmphi1 = q.b.hi; 0894 b6 13 lda $13 ac=tsr; 0896 b6 64 lda $64 ocmplo1 = q.b.lo; 0898 b7 17 sta $17 089a 81 rts } /*************************************************************************/ void timercmp (void) /* timer service module */ 1ff6 08 9b { f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3228 motorola sensor device data www.motorola.com/semiconductors 089b 33 02 com $02 portc =~ portc; /* service the lcd */ 089d 33 01 com $01 portb =~ portb; 089f 33 00 com $00 porta =~ porta; 08a1 ad dd bsr $0880 fixcompare(); 08a3 80 rti } /************************************************************************/ void adzero(void) /* called by initio() to save initial xdcr's zero pressure offset voltage output */ { 08a4 4f clra for ( j=0; j<20; ++j) /* give the sensor time to owarmupo and the 08a5 3f 57 clr $57 08a7 b7 58 sta $58 08a9 b6 57 lda $57 08ab b7 60 sta $60 08ad b6 58 lda $58 08af b7 61 sta $61 08b1 b6 61 lda $61 08b3 a0 14 sub #$14 08b5 b6 60 lda $60 08b7 a2 00 sbc #$00 08b9 24 0b bcc $08c6 power supply time to settle down */ { 08bb cd 08 17 jsr $0817 delay(); } 08be 3c 61 inc $61 08c0 26 02 bne $08c4 08c2 3c 60 inc $60 08c4 20 eb bra $08b1 08c6 cd 08 37 jsr $0837 xdcr_offset = read_a2d(); 08c9 3f 5c clr $5c 08cb b7 5d sta $5d 08cd 81 rts } /**************************************************************************/ void initio (void) /* setup the i/o */ { 08ce a6 20 lda #$20 adstat = 0x20; /* powerup the a/d */ 08d0 b7 09 sta $09 08d2 3f 02 clr $02 porta = portb = portc = 0; 08d4 3f 01 clr $01 08d6 3f 00 clr $00 08d8 a6 ff lda #$ff ddra = ddrb = ddrc = 0xff; 08da b7 06 sta $06 08dc b7 05 sta $05 08de b7 04 sta $04 08e0 b6 13 lda $13 ac=tsr; /* dummy read */ 08e2 3f 1e clr $1e ocmphi1 = ocmphi2 = 0; 08e4 3f 16 clr $16 08e6 b6 1f lda $1f ac = ocmplo2; /* clear out output compare 2 if it happens to be set */ 08e8 ad 96 bsr $0880 fixcompare(); /* setup for the first timer interrupt */ f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3229 motorola sensor device data www.motorola.com/semiconductors 08ea a6 40 lda #$40 tcr = 0x40; 08ec b7 12 sta $12 08ee 9a cli cli; /* let the interrupts begin ! */ /* write cal to the display */ 08ef a6 cc lda #$cc portc = 0xcc; /* c */ 08f1 b7 02 sta $02 08f3 a6 be lda #$be portb = 0xbe; /* a */ 08f5 b7 01 sta $01 08f7 a6 c4 lda #$c4 porta = 0xc4; /* l */ 08f9 b7 00 sta $00 08fb ad a7 bsr $08a4 adzero(); 08fd 81 rts } /**************************************************************************/ void cvt_bin_dec(unsigned long arg) /* first converts the argument to a five digit decimal value. the msd is in the lowest address. then leading zero suppresses the value and writes it to the display ports. the argument value range is 0..65535 decimal. */ 0069 { 08fe bf 69 stx $69 0900 b7 6a sta $6a 006b char i; 006c unsigned long l; 0902 4f clra for ( i=0; i < 5; ++i ) 0903 b7 6b sta $6b 0905 b6 6b lda $6b 0907 a1 05 cmp #$05 0909 24 07 bcc $0912 { 090b 97 tax digit[i] = 0x0; /* put blanks in all digit positions */ 090c 6f 50 clr $50,x } 090e 3c 6b inc $6b 0910 20 f3 bra $0905 0912 4f clra for ( i=0; i < 4; ++i ) 0913 b7 6b sta $6b 0915 b6 6b lda $6b 0917 a1 04 cmp #$04 0919 24 70 bcc $098b { 091b 97 tax if ( arg >= dectable [i] ) 091c 58 lslx 091d d6 08 0b lda $080b,x 0920 b1 6a cmp $6a 0922 26 07 bne $092b 0924 d6 08 0a lda $080a,x 0927 b1 69 cmp $69 0929 27 5c beq $0987 { 092b be 6b ldx $6b l = dectable[i]; 092d 58 lslx 092e d6 08 0a lda $080a,x f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3230 motorola sensor device data www.motorola.com/semiconductors 0931 b7 6c sta $6c 0933 d6 08 0b lda $080b,x 0936 b7 6d sta $6d 0938 b6 6a lda $6a digit[i] = arg / l; 093a b7 58 sta $58 093c b6 69 lda $69 093e b7 57 sta $57 0940 b6 6c lda $6c 0942 b7 66 sta $66 0944 b6 6d lda $6d 0946 b7 67 sta $67 0948 cd 0a 5e jsr $0a5e 094b cd 0a 8f jsr $0a8f 094e bf 57 stx $57 0950 b7 58 sta $58 0952 be 6b ldx $6b 0954 e7 50 sta $50,x 0956 be 6b ldx $6b arg = arg(digit[i] * l); 0958 e6 50 lda $50,x 095a 3f 57 clr $57 095c b7 58 sta $58 095e b6 6c lda $6c 0960 b7 66 sta $66 0962 b6 6d lda $6d 0964 b7 67 sta $67 0966 cd 0a 3f jsr $0a3f 0969 bf 57 stx $57 096b b7 58 sta $58 096d 33 57 com $57 096f 30 58 neg $58 0971 26 02 bne $0975 0973 3c 57 inc $57 0975 b6 58 lda $58 0977 bb 6a add $6a 0979 b7 58 sta $58 097b b6 57 lda $57 097d b9 69 adc $69 097f b7 57 sta $57 0981 b7 69 sta $69 0983 b6 58 lda $58 0985 b7 6a sta $6a } } 0987 3c 6b inc $6b 0989 20 8a bra $0915 098b b6 6a lda $6a digit[i] = arg; 098d b7 58 sta $58 098f b6 69 lda $69 0991 b7 57 sta $57 0993 be 6b ldx $6b 0995 b6 58 lda $58 0997 e7 50 sta $50,x /* now zero suppress and send the lcd pattern to the display */ 0999 9b sei sei; f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3231 motorola sensor device data www.motorola.com/semiconductors 099a 3d 50 tst $50 if ( digit[0] == 0 ) /* leading zero suppression */ 099c 26 04 bne $09a2 099e 3f 02 clr $02 portc = 0; 09a0 20 07 bra $09a9 else 09a2 be 50 ldx $50 portc = ( lcdtab[digit[0]] ); /* 100's digit */ 09a4 d6 08 00 lda $0800,x 09a7 b7 02 sta $02 09a9 3d 50 tst $50 if ( digit[0] == 0 && digit[1] == 0 ) 09ab 26 08 bne $09b5 09ad 3d 51 tst $51 09af 26 04 bne $09b5 09b1 3f 01 clr $01 portb=0; 09b3 20 07 bra $09bc else 09b5 be 51 ldx $51 portb = ( lcdtab[digit[1]] ); /* 10's digit */ 09b7 d6 08 00 lda $0800,x 09ba b7 01 sta $01 09bc be 52 ldx $52 porta = ( lcdtab[digit[2]]+1 ); /* 1's digit + decimal point */ 09be d6 08 00 lda $0800,x 09c1 4c inca 09c2 b7 00 sta $00 09c4 9a cli cli; 09c5 cd 08 17 jsr $0817 delay(); 09c8 81 rts } /****************************************************************/ void display_psi(void) /* at powerup it is assumed that the pressure port of the sensor is open to atmosphere. the code in initio() delays for the sensor and power to stabilize. one hundred a/d conversions are averaged and divided by 100. the result is called xdcr_offset. this routine calls the a/d routine which performs one hundred conversions, divides the result by 100 and returns the value. if the value returned is less than or equal to the xdcr_offset, the value of xdcr_offset is substituted. if the value returned is greater than xdcr_offset, xdcr_offset is subtracted from the returned value. that result is multiplied by a constant to yield pressure in psi * 10 to yield a odecimal pointo. */ { while(1) { 09c9 3f 59 clr $59 slope = 64; 09cb a6 40 lda #$40 09cd b7 5a sta $5a 09cf b6 03 lda $03 k = portd & 0xc0; /* this lets us orubbero the slope to closer fit 09d1 a4 c0 and #$c0 09d3 b7 62 sta $62 the slope of the sensor */ 09d5 a1 80 cmp #$80 if ( k == 0x80 ) /* j2 removed, j1 installed */ 09d7 26 06 bne $09df 09d9 3f 59 clr $59 slope = 65; 09db a6 41 lda #$41 09dd b7 5a sta $5a 09df b6 62 lda $62 if ( k == 0x40 ) /* j1 removed, j2 installed */ f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3232 motorola sensor device data www.motorola.com/semiconductors 09e1 a1 40 cmp #$40 09e3 26 06 bne $09eb 09e5 3f 59 clr $59 slope = 63; 09e7 a6 3f lda #$3f 09e9 b7 5a sta $5a /* else both jumpers are removed or installed... don't change the slope */ 09eb cd 08 37 jsr $0837 atodtemp = read_a2d(); /* atodtemp = raw a/d ( 0..255 ) */ 09ee 3f 55 clr $55 09f0 b7 56 sta $56 09f2 b0 5d sub $5d if ( atodtemp <= xdcr_offset ) 09f4 b7 58 sta $58 09f6 b6 5c lda $5c 09f8 a8 80 eor #$80 09fa b7 57 sta $57 09fc b6 55 lda $55 09fe a8 80 eor #$80 0a00 b2 57 sbc $57 0a02 ba 58 ora $58 0a04 22 08 bhi $0a0e 0a06 b6 5c lda $5c atodtemp = xdcr_offset; 0a08 b7 55 sta $55 0a0a b6 5d lda $5d 0a0c b7 56 sta $56 0a0e b6 56 lda $56 atodtemp = xdcr_offset; /* remove the offset */ 0a10 b0 5d sub $5d 0a12 b7 56 sta $56 0a14 b6 55 lda $55 0a16 b2 5c sbc $5c 0a18 b7 55 sta $55 0a1a b6 56 lda $56 atodtemp *= slope; /* convert to psi */ 0a1c b7 58 sta $58 0a1e b6 55 lda $55 0a20 b7 57 sta $57 0a22 b6 59 lda $59 0a24 b7 66 sta $66 0a26 b6 5a lda $5a 0a28 b7 67 sta $67 0a2a cd 0a 3f jsr $0a3f 0a2d bf 55 stx $55 0a2f b7 56 sta $56 0a31 cd 08 fe jsr $08fe cvt_bin_dec( atodtemp ); /* convert to decimal and display */ 0a34 20 93 bra $09c9 } 0a36 81 rts } /************************************************************************/ main() { 0a37 cd 08 ce jsr $08ce initio(); /* setup the processor's i/o */ 0a3a ad 8d bsr $09c9 display_psi(); 0a3c 20 fe bra $0a3c while(1); /* should never get here */ 0a3e 81 rts } 0a3f be 58 ldx $58 0a41 b6 67 lda $67 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3233 motorola sensor device data www.motorola.com/semiconductors 0a43 42 mul 0a44 b7 70 sta $70 0a46 bf 71 stx $71 0a48 be 57 ldx $57 0a4a b6 67 lda $67 0a4c 42 mul 0a4d bb 71 add $71 0a4f b7 71 sta $71 0a51 be 58 ldx $58 0a53 b6 66 lda $66 0a55 42 mul 0a56 bb 71 add $71 0a58 b7 71 sta $71 0a5a 97 tax 0a5b b6 70 lda $70 0a5d 81 rts 0a5e 3f 70 clr $70 0a60 5f clrx 0a61 3f 6e clr $6e 0a63 3f 6f clr $6f 0a65 5c incx 0a66 38 58 lsl $58 0a68 39 57 rol $57 0a6a 39 6e rol $6e 0a6c 39 6f rol $6f 0a6e b6 6e lda $6e 0a70 b0 67 sub $67 0a72 b7 6e sta $6e 0a74 b6 6f lda $6f 0a76 b2 66 sbc $66 0a78 b7 6f sta $6f 0a7a 24 0d bcc $0a89 0a7c b6 67 lda $67 0a7e bb 6e add $6e 0a80 b7 6e sta $6e 0a82 b6 66 lda $66 0a84 b9 6f adc $6f 0a86 b7 6f sta $6f 0a88 99 sec 0a89 59 rolx 0a8a 39 70 rol $70 0a8c 24 d8 bcc $0a66 0a8e 81 rts 0a8f 53 comx 0a90 9f txa 0a91 be 70 ldx $70 0a93 53 comx 0a94 81 rts 1ffe 0a 37 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3234 motorola sensor device data www.motorola.com/semiconductors symbol table label value label value label value label value irq 0813 | sci 0816 | timercap 0814 | timercmp 089b timerov 0815 | __ldiv 0a5e | __longix 0066 | __mul 0000 __mul16x16 0a3f | __rdiv 0a8f | __reset 1ffe | __startup 0000 __stop 0000 | __swi 0812 | __wait 0000 | __longac 0057 acnthi 001a | acntlo 001b | adcnt 005b | addata 0008 adstat 0009 | adzero 08a4 | arg 0069 | atodtemp 0055 b 0000 | bothbytes 0002 | cvt_bin_dec 08fe | ddra 0004 ddrb 0005 | ddrc 0006 | dectable 080a | delay 0817 digit 0050 | display_psi 09c9 | eeclk 0007 | fixcompare 0880 hi 0000 | i 005e | icaphi1 0014 | icaphi2 001c icaplo1 0015 | icaplo2 001d | initio 08ce | isboth 0002 j 0060 | k 0062 | l 0000 | lcdtab 0800 lo 0001 | main 0a37 | misc 000c | ocmphi1 0016 ocmphi2 001e | ocmplo1 0017 | ocmplo2 001f | plma 000a plmb 000b | porta 0000 | portb 0001 | portc 0002 portd 0003 | q 0063 | read_a2d 0837 | scibaud 000d scicntl1 000e | scicntl2 000f | scidata 0011 | scistat 0010 slope 0059 | tcnthi 0018 | tcntlo 0019 | tcr 0012 tsr 0013 | xdcr_offset 005c | memory usage map ('x' = used, '' = unused) 0100 : 0140 : 0180 : 01c0 : x 0800 : xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx 0840 : xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx 0880 : xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx 08c0 : xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx 0900 : xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx 0940 : xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx 0980 : xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx 09c0 : xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx 0a00 : xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx 0a40 : xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx 0a80 : xxxxxxxxxxxxxxxx xxxxx 0ac0 : 1f00 : 1f40 : 1f80 : 1fc0 : xxxxxxxxxxxxxx all other memory blocks unused. errors : 0 warnings : 0 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3235 motorola sensor device data www.motorola.com/semiconductors prepared by: warren schultz discrete applications engineering introduction compensated semiconductor pressure sensors such as the mpx2000 family are relatively easy to interface with digital systems. with these sensors and the circuitry described herein, pressure is translated into a 0.5 to 4.5 volt output range that is directly compatible with microcomputer a/d inputs. the 0.5 to 4.5 volt range also facilitates interface with an lm3914, making bar graph pressure gauges relatively simple. figure 1. devb147 compensated pressure sensor evaluation board (board no longer available)
semiconductor application note rev 1 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3236 motorola sensor device data www.motorola.com/semiconductors evaluation board description the information required to use evaluation board number devb147 follows, and a discussion of the design appears in the design considerations section. function the evaluation board shown in figure 1 is supplied with an mpx2100dp sensor and provides a 100 kpa full scale pressure measurement. it has two input ports. p1, the pressure port, is on the top side of the sensor and p2, a vacuum port, is on the bottom side. these ports can be supplied up to 100 kpa (15 psi) of pressure on p1 or up to 100 kpa of vacuum on p2, or a differential pressure up to 100 kpa between p1 and p2. any of these sources will produce the same output. the primary output is a 10 segment led bar graph, which is labeled in increments of 10% of full scale, or 10 kpa with the mpx2100 sensor. an analog output is also provided. it nominally supplies 0.5 volts at zero pressure and 4.5 volts at full scale. zero and full scale adjustments are made with potentiometers so labeled at the bottom of the board. both adjustments are independent of one another. electrical characteristics the following electrical characteristics are included as a guide to operation. characteristic symbol min typ max units power supply voltage b+ 6.8 e 13.2 dc volts full scale pressure p fs e e 100 kpa overpressure p max e e 700 kpa analog full scale v fs e 4.5 e volts analog zero pressure offset v off e 0.5 e volts analog sensitivity s aout e 40 e mv/kpa quiescent current i cc e 40 e ma full scale current i fs e 160 e ma content board contents are described in the parts list shown in table 1. a schematic and silk screen plot are shown in figures 2 and 6. a pin by pin circuit description follows. pin-by-pin description b+: input power is supplied at the b+ terminal. minimum input voltage is 6.8 volts and maximum is 13.2 volts. the upper limit is based upon power dissipation in the lm3914 assuming all 10 led's are lit and ambient temperature is 25 c. the board will survive input transients up to 25 volts provided that average power dissipation in the lm3914 does not exceed 1.3 watts. out: an analog output is supplied at the out terminal. the signal it provides is nominally 0.5 volts at zero pressure and 4.5 volts at full scale. zero pressure voltage is adjustable and set with r11. this output is designed to be directly connected to a microcomputer a/d channel, such as one of the e ports on an mc68hc11. gnd: there are two ground connections. the ground terminal on the left side of the board is intended for use as the power supply return. on the right side of the board one of the test point terminals is also connected to ground. it provides a convenient place to connect instrumentation grounds. tp1: test point 1 is connected to the lm3914's full scale reference voltage which sets the trip point for the uppermost led segment. this voltage is adjusted via r1 to set full scale pressure. tp2: test point 2 is connected to the +5.0 volt regulator output. it can be used to verify that supply voltage is within its 4.75 to 5.25 volt tolerance. p1, p2: pressure and vacuum ports p1 and p2 protrude from the sensor on the right side of the board. pressure port p1 is on the top and vacuum port p2 is on the bottom. neither port is labeled. maximum safe pressure is 700 kpa. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3237 motorola sensor device data www.motorola.com/semiconductors + r5 1 k r1 1 k + + + r3 1.2 k r2 2.7 k r12 470 r14 470 r4 1 k r9 1 k r10 820 r13 1 k r11 200 b+ s1 on/off mc78l05acp u1 3 2 1 i g o c2 0.1 m f c1 1 m f gnd analog out zero cal. 10 9 u3c mc33274 8 11 mc33274 mc33274 mc33274 u3b u3a 12 13 6 5 2 3 4 7 14 1 u3d r7 75 r8 75 32 1 4 xdcr1 mpx2100dp full scale cal. lm3914n u2 d1 d9 d10 d2 d3 d4 d5 d6 d7 d8 d1-d10 mv5716 4 bar graph tp1 (full scale voltage) gnd tp2 +5 volts d11 mv57124a power on indicator led gnd b+ rlo sig rhi ref adj mod led 1 2 3 4 5 6 7 8 910 11 12 13 14 15 16 17 18 figure 2. compensated pressure sensor evb schematic r6 7.5 k led led led led led led led led + + + + b+ c1 0.1 m f c2 1 m f gnd u1 3 2 1 32 41 5 6 4 7 mc33274 i g o mc78l05acp u2b r4 1 k r5 1 k 13 12 r3 100 k u2d u2a 3 2 output 1 r2 1 k r1 1 k mc33274 mc33274 14 u2c mc33274 8 10 9 r6 1 k r7 1 k v offset figure 3. compensated sensor interface note: for zero pressure voltage independent of sensor common mode r6/r7 = r2/r1 xdcr mpx2100 11 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3238 motorola sensor device data www.motorola.com/semiconductors design considerations in this type of application the design challenge is how to take a relatively small dc coupled differential signal and produce a ground referenced output that is suitable for driving microcomputer a/d inputs. a user friendly interface circuit that will do this job is shown in figure 3. it uses one quad op amp and several resistors to amplify and level shift the sensor's output. most of the amplification is done in u2d which is configured as a differential amplifier. it is isolated from the sensor's positive output by u2b. the purpose of u2b is to prevent feedback current that flows through r3 and r4 from flowing into the sensor. at zero pressure the voltage from pin 2 to pin 4 on the sensor is zero volts. for example with the common mode voltage at 2.5 volts, the zero pressure output voltage at pin 14 of u2d is then 2.5 volts, since any other voltage would be coupled back to pin 13 via r3 and create a nonzero bias across u2d's differential inputs. this 2.5 volt zero pressure dc output voltage is then level translated to the desired zero pressure offset voltage (v offset ) by u2c and u2a. to see how the level translation works, assume 0.5 volts at (v offset ). with 2.5 volts at pin 10, pin 9 is also at 2.5 volts. this leaves 2.5 0.5 = 2.0 volts across r7. since no current flows into pin 9, the same current flows through r6, producing 2.0 volts across r6 also. adding the voltages (0.5 + 2.0 + 2.0) yields 4.5 volts at pin 8. similarly 2.5 volts at pin 3 implies 2.5 volts at pin 2, and the drop across r2 is 4.5 v 2.5 v = 2.0 volts. again 2.0 volts across r2 implies an equal drop across r1, and the voltage at pin 1 is 2.5 v 2.0 v = 0.5 volts. for this dc output voltage to be independent of the sensor's common mode voltage it is necessary to satisfy the condition that r6/r7 = r2/r1. gain is close but not exactly equal to r3/r4(r1/r2+1), which predicts 200.0 for the values shown in figure 3. a more exact calculation can be performed by doing a nodal analysis, which yields 199.9. cascading the gains of u2d and u2a using standard op amp gain equations does not give an exact result, because the sensor's negative going differential signal at pin 4 subtracts from the dc level that is amplified by u2a. the resulting 0.5 v to 4.5 v output from u2a is directly compatible with microprocessor a/d inputs. tying this output to an lm3914 for a bar graph readout is also very straight forward. the block diagram that appears in figure 4 shows the lm3914's internal architecture. since the lower resistor in the input comparator chain is pinned out at r lo , it is a simple matter to tie this pin to a voltage that is approximately equal to the interface circuit's 0.5 volt zero pressure output voltage. in figure 2, this is accomplished by dividing down the 5.0 volt regulator's output voltage through r13 and adjustment pot r11. the voltage generated at r11's wiper is the offset voltage identified as v offset in figure 3. its source impedance is chosen to keep the total input impedance to u3c at approximately 1k. the wiper of r11 is also fed into r lo for zeroing the bar graph. the full scale measurement is set by adjusting the upper comparator's reference voltage to match the sensor's output at full pressure. an internal regulator on the lm3914 sets this voltage with the aid of resistors r2, r3, and adjustment pot r1 that are shown in figure 2. five volt regulated power is supplied by an mc78l05. the led's are powered directly from lm3914 outputs, which are set up as current sources. output current to each led is approximately 10 times the reference current that flows from pin 7 through r3, r1, and r2 to ground. in this design it is nominally (4.5 v/4.9k)10 = 9.2 ma. over a zero to 50 c temperature range combined accuracy for the sensor, interface and driver ic are +/ 10%. given a 10 segment display total accuracy for the bar graph readout is approximately +/ (10 kpa +10%). application using the analog output to provide pressure information to a microcomputer is very straightforward. the output voltage range, which goes from 0.5 volts at zero pressure to 4.5 volts at full scale, is designed to make optimum use of microcomputer a/d inputs. a direct connection from the evaluation board analog output to an a/d input is all that is required. using the mc68hc11 as an example, the output is connected to any of the e ports, such as port e0 as shown in figure 5. to get maximum accuracy from the a/d conversion, v refh is tied to 4.85 volts and v refl is tied to 0.3 volts by dividing down a 5.0 volt reference with 1% resistors. conclusion perhaps the most noteworthy aspect to the bar graph pressure gauge described here is the ease with which it can be designed. the interface between an mpx2000 series sensor and lm3914 bar graph display driver consists of one quad op amp and a few resistors. the result is a simple and inexpensive circuit that is capable of measuring pressure, vacuum, or differential pressure with an output that is directly compatible to a microprocessor. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3239 motorola sensor device data www.motorola.com/semiconductors figure 4. lm3914 block diagram reference voltage source 1.25 v mode select amplifier + buffer ref out this load determines led brightness controls type of display, bar or single led comparator 1 of 10 lm3914 10 11 12 13 14 15 16 17 18 1 1 k 1 k 1 k 1 k 1 k 1 k 1 k 1 k 1 k 1 k led v + r hi 6 7 8 3 4 5 r lo ref adj v + sig in v 9 2 from pin 11 v + 20 k + + + + + + + + + + + f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3240 motorola sensor device data www.motorola.com/semiconductors gnd b+ analog out +12 v compensated sensor bar graph pressure gauge 15 ohms 1% 453 ohms 1% 30.1 ohms 1% 4.85 v 0.302 v v refh v refl 0 1 2 3 4 5 6 7 port e mc68hc11 figure 5. application example pressure/ vacuum in +5 v r12 r2 r3 r10 r9 r4 r5 r8 r6 r7 r12 r2 r3 r10 r9 r4 r5 r8 r6 r7 r14 r13 r14 r13 r11 r1 zero full scale tp2 tp1 gnd power + on off motorola discrete applications b+ out gnd sensor u1 u3 c1 c2 u3 lm3914n mv57164 % full scale compensated pressure sensor evb u2 devb147 100 90 70 60 50 40 30 20 10 80 figure 6. silk screen f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3241 motorola sensor device data www.motorola.com/semiconductors table 1. parts list designator qty. description value vendor part c1 c2 1 1 ceramic capacitor ceramic capacitor 1.0 m f 0.1 m f d1-d10 d11 1 1 bar graph led led gi gi mv57164 mv57124a r2 r3 r4, r5, r9, r13 r6 r7, r8 r10 r12, r14 r1 r11 1 1 4 1 2 1 2 1 1 1/4 watt film resistor 1/4 watt film resistor 1/4 watt film resistor 1/4 watt film resistor 1/4 watt film resistor 1/4 watt film resistor 1/4 watt film resistor trimpot trimpot 2.7k 1.2k 1.0k 7.5k 75 820 470 1.0k 200 bourns bourns 3386p-1-102 3386p-1-201 s1 1 switch nkk 12sdp2 u1 u2 u3 1 1 1 5.0 v regulator bar graph ic op amp motorola national motorola mc78l05acp lm3914n mc33274p xdcr1 1 pressure sensor motorola mpx2100dp e e e e 1 1 1 1 terminal block test point terminal (black) test point terminal (red) test point terminal (yellow) augat components corp. components corp. components corp. 2sv03 tp1040100 tp1040102 tp1040104 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3242 motorola sensor device data www.motorola.com/semiconductors #"! $ ! ! ! " ! prepared by: bill lucas discrete applications engineering introduction outputs from compensated and calibrated semiconductor pressure sensors such as the mpx2000 series devices are easily amplified and interfaced to a microprocessor. design considerations and the description of an evaluation board using a simple analog interface connected to a microprocessor is presented here. purpose the evaluation system shown in figure 1 shows the ease of operating and interfacing the motorola mpx2000 series pressure sensors to a quad operational amplifier, which amplifies the sensor's output to an acceptable level for an analogtodigital converter. the output of the op amp is connected to the a/d converter of the microprocessor and that analog value is then converted to engineering units and displayed on a liquid crystal display (lcd). this system may be used to evaluate any of the mpx2000 series pressure sensors for your specific application. description the devb158 evaluation system is constructed on a small printed circuit board. designed to be powered from a 12 vdc power supply, the system will display the pressure applied to the mpx2000 series sensor in pounds per square inch (psi) on the liquid crystal display. table 1 shows the pressure sensors that may be used with the system and the pressure range associated with that particular sensor as well as the jumper configuration required to support that sensor. these jumpers are installed at assembly time to correspond with the supplied sensor. should the user chose to evaluate a different sensor other than that supplied with the board, the jumpers must be changed to correspond to table 1 for the new sensor. the displayed pressure is scaled to the full scale (psi) range of the installed pressure sensor. no potentiometers are used in the system to adjust its span and offset. this function is performed by software. figure 1. devb158 2000 series lcd pressure gauge evb (board no longer available)
semiconductor application note rev 1 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3243 motorola sensor device data www.motorola.com/semiconductors table 1. input pressure jumpers sensor type input pressure psi j8 j3 j2 j1 mpx2010 0 1.5 in in in in mpx2050 0 7.5 out in in out mpx2100 0 15.0 out in out in mpx2200 030 out in out out the signal conditioned sensor's zero pressure offset voltage with no pressure applied to the sensor is empirically computed each time power is applied to the system and stored in ram. the sensitivity of the mpx2000 series pressure sensors is quite repeatable from unit to unit. there is a facility for a small adjustment of the slope constant built into the program. it is accomplished via jumpers j4 thru j7, and will be explained in the operation section. figure 2 shows the printed circuit silkscreen and figures 3a and 3b show the schematic for the system. j1 j2 j3 j4 j5 j6 j7 rp1 lcd1 r11 u5 u2 tp1 r15 y1 c8 c6 c1 c2 p1 +12 gnd u3 u4 c5 c4 r14 r6 j8 xdcr1 devb158 u1 motorola discrete applications engineering d1 r4 r8 r5 r7 r9 r10 r2 r3 r12 r13 d2 c3 c7 r1 2.9 5.2 figure 2. printed circuit silkscreen f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3244 motorola sensor device data www.motorola.com/semiconductors the analog section of the system can be broken down into two subsections. these sections are the power supply and the amplification section. the power supply section consists of a diode, used to protect the system from input voltage reversal, and two fixed voltage regulators. the 5 volt regulator (u3) is used to power the microprocessor and display. the 8 volt regulator (u4) is used to power the pressure sensor, voltage references and a voltage offset source. the microprocessor section (u5) requires minimal support hardware to function. the mc34064p5 (u2) provides an under voltage sense function and is used to reset the microprocessor at system powerup. the 4.0 mhz crystal (y1) provides the external portion of the oscillator function for clocking the microprocessor and providing a stable base for timing functions. table 2. parts list designators quant. description rating manufacturer part number c3, c4, c6 3 0.1 m f ceramic cap. 50 vdc sprague 1c105z5u104m050b c1, c2, c5 3 1 m f ceramic cap. 50 vdc murata erie rpe123z5u105m050v c7, c8 2 22 pf ceramic cap. 100 vdc mepco/centralab cn15a220k j1 j3, j8 3 or 4 #22 or #24 awg tined copper as required j4 j7 1 dual row straight 4 pos. arranged on 0.1 grid amp 872272 lcd1 1 liquid crystal display iee lcd5657 p1 1 power connector phoenix contact mkds 1/23.81 r1 1 6.98k ohm resistor 1% r2 1 121 ohm resistor 1% r3 1 200 ohm resistor 1% r4, r11 2 4.7k ohm resistor r7 1 340 ohm resistor 1% r5, r6 2 2.0k ohm resistor 1% r8 1 23.7 ohm resistor 1% r9 1 976 ohm resistor 1% r10 1 1k ohm resistor 1% r12 1 3.32k ohm resistor 1% r13 1 4.53k ohm resistor 1% r14 1 402 ohm resistor 1% r15 1 10 meg ohm resistor rp1 1 47k ohm x 7 sip resistor 2% cts 770 series tp1 1 test point red components corp. tp1040102 u1 1 quad operational amplifier motorola mc33274p u2 1 under voltage detector motorola mc34064p5 u3 1 5 volt fixed voltage regulator motorola mc78l05acp u4 1 8 volt fixed voltage regulator motorola mc78l08acp u5 1 microprocessor motorola motorola mc68hc705b5fn or xc68hc705b5fn xdcr 1 pressure sensor motorola mpx2xxxdp y1 1 crystal (low profile) 4.0 mhz cts ats040slv no designator 1 52 pin plcc socket for u5 amp 8215751 no designator 4 jumpers for j4 thru j7 molex 15291025 no designator 1 bare printed circuit board no designator 4 self sticking feet fastex 503301005001 note: all resistors are 1/4 w resistors with a tolerance of 5% unless otherwise noted. note: all capacitors are 100 volt, ceramic capacitors with a tolerance of 10% unless otherwise noted. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3245 motorola sensor device data www.motorola.com/semiconductors operational characteristics the following operational characteristics are included as a guide to operation. characteristic symbol min max unit power supply voltage +12 10.75 16 volts operating current i cc 75 ma full scale pressure mpx2010 mpx2050 mpx2100 mpx2200 p fs 1.5 7.5 15 30 psi psi psi psi pinbypin description +12: input power is supplied at the +12 terminal. the minimum operating voltage is 10.75 vdc and the maximum operating voltage is 16 vdc. gnd: the ground terminal is the power supply return for the system. tp1: test point 1 is connected to the final op amp stage. it is the voltage that is applied to the microprocessor's a/d converter. there are two ports on the pressure sensor located at the bottom center of the printed circuit board. the pressure port is on the top left and the vacuum port is on the bottom right of the sensor. + + + + pd1 2a2 pd2 2a3 pd3 2a3 pd4 2a3 pd5 2a3 pd6 2a3 pd7 2a3 +12 in ground p1 1n4002 d1 1 m f + c1 u4 78l08 in out ground u3 78l05 in out ground 1 m f + 0.1 c2 c3 +5 v +8 r12 r13 r14 vrh 2d4 vrl 2d4 402 3.32k 1 m f + c5 0.1 c4 cpu_reset 2b4 mc34064p5 +in gnd out u2 +5 v +5 v r11 4.7k pd0 2a2 tp1 +5 v 1n914 4.7k r4 8 10 9 r5 2k r6 2k 14 12 13 u1a u1c u1d u1b 3 2 11 1 976 r9 1k r10 340 r7 r8 23.7 +8 +8 14 23 xdcr1 121 r2 200 r3 6.98k r1 5 6 4 7 +12 v mc33274 d2 +5 v 7 x 47k j1 j2 j3 j4 j5 j6 j7 sensor type select slope adj. figure 3a. schematic j8 is installed for the mpx2010 only j8 4.53k f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3246 motorola sensor device data www.motorola.com/semiconductors 0217 6543 0 2 17 6 543 20 49 47 48 42 43 44 45 46 39 37 38 32 33 34 35 36 17 6 543 31 29 30 24 25 26 27 28 28 37 36 5 6 7 34 35 8 31 32 9 10 11 29 30 12 26 27 13 14 15 24 25 16 22 23 17 18 19 20 1 21 blk pln pins: 24, 33, 3840 c7 c8 22 pf 22 pf 17 r15 10m osc2 osc1 16 4.00 mhz y1 porta portb portc u5 mc68hc705b5 pd0 pd1 pd2 pd3 pd4 pd5 pd6 pd7 pd0 pd1 pd2 pd1 pd4 pd5 pd6 pd7 1-c2 1-e3 1-e3 1-e3 1-e3 1-e4 1-e4 1-e4 14 13 12 11 9 5 4 3 irq* reset* vpp6 vdd vss tcap1 d/a rdi tdo vrl vrh plma tcap2 19 18 15 10 41 22 23 21 50 52 7 8 20 +5 v cpu_reset 1-e2 0.1 c6 vrl 1-c4 vrh 1-c4 lcd1 figure 3b. schematic f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3247 motorola sensor device data www.motorola.com/semiconductors operation connect the system to a 12 vdc regulated power supply. (note the polarity marked on the power terminal p1.) depending on the particular pressure sensor being used with the system, wire jumpers j1 through j3 and j8 must be installed at board assembly time. if at some later time it is desirable to change the type of sensor that is installed on the board, jumpers j1 through j3 and j8, must be reconfigured for the system to function properly (see table 1). if an invalid j1 through j3 jumper combination (i.e., not listed in table 1) is used the lcd will display aseo to indicate that condition. these jumpers are read by the software and are used to determine which sensor is installed on the board. wire jumper j8 is installed only when an mpx2010dp pressure sensor is used on the system. the purpose of wire jumper j8 will be explained later in the text. jumpers j4 through j7 are read by the software to allow the user to adjust the slope constant used for the engineering units calculation (see table 3). the pressure and vacuum ports on the sensor must be left open to atmosphere anytime the board is poweredup. this is because the zero pressure offset voltage is computed at powerup. when you apply power to the system, the lcd will display cal for approximately 5 seconds. after that time, pressure or vacuum may be applied to the sensor. the system will then start displaying the applied pressure in psi. table 3. j7 j6 j5 j4 action in in in in normal slope in in in out decrease the slope approximately 7% in in out in decrease the slope approximately 6% in in out out decrease the slope approximately 5% in out in in decrease the slope approximately 4% in out in out decrease the slope approximately 3% in out out in decrease the slope approximately 2% in out out out decrease the slope approximately 1% out in in in increase the slope approximately 1% out in in out increase the slope approximately 2% out in out in increase the slope approximately 3% out in out out increase the slope approximately 4% out out in in increase the slope approximately 5% out out in out increase the slope approximately 6% out out out in increase the slope approximately 7% out out out out normal slope to improve the accuracy of the system, you can change the constant used by the program that determines the span of the sensor and amplifier. you will need an accurate test gauge (using psi as the reference) to measure the pressure applied to the sensor. anytime after the display has completed the zero calculation, (after cal is no longer displayed) apply the sensor's full scale pressure (see table 1), to the sensor. make sure that jumpers j4 through j7 are in the anormalo configuration (see table 3). referring to table 3, you can better acalibrateo the system by changing the configuration of j4 through j7. to acalibrateo the system, compare the display reading against that of the test gauge (with j4 through j7 in the anormal slopeo configuration). change the configuration of j4 through j7 according to table 3 to obtain the best results. the calibration jumpers may be changed while the system is powered up as they are read by the software before each display update. design considerations to build a system that will show how to interface an mpx2000 series pressure sensor to a microprocessor, there are two main challenges. the first is to take a small differential signal produced by the sensor and produce a ground referenced signal of sufficient amplitude to drive a microprocessor's a/d input. the second challenge is to understand the microprocessor's operation and to write software that makes the system function. from a hardware point of view, the microprocessor portion of the system is straight forward. the microprocessor needs power, a clock source (crystal y1, two capacitors and a resistor), and a reset signal to make it function. as for the a/d converter, external references are required to make it function. in this case, the power source for the sensor is divided to produce the voltage references for the a/d converter. accurate results will be achieved since the output from the sensor and the a/d references are ratiometric to its power supply voltage. the liquid crystal display is driven by ports a, b and c of the microprocessor. there are enough i/o lines on these ports to provide drive for three full digits, the backplane and two decimal points. software routines provide the ac waveform necessary to drive the display. the analog portion of the system consists of the pressure sensor, a quad operational amplifier and the voltage references for the microprocessor's a/d converter and signal conditioning circuitry. figure 4 shows an interface circuit that will provide a single ended signal with sufficient amplitude to drive the microprocessor's a/d input. it uses a quad operational amplifier and several resistors to amplify and level shift the sensor's output. it is necessary to level shift the output from the final amplifier into the a/d. using single power supplied op amps, the v ce saturation of the output from an op amp cannot be guaranteed to pull down to zero volts. the analog design shown here will provide a signal to the a/d converter with a span of approximately 4 volts when zero to fullscale pressure is applied to the sensor. the final amplifier's output is level shifted to approximately 0.7 volts. this will provide a signal that will swing between approximately 0.7 volts and 4.7 volts. the offset of 0.7 volts in this implementation does not have to be trimmed to an exact point. the software will sample the voltage applied to the a/d converter at initial power up time and call that value azeroo. the important thing to remember is that the span of the signal will be approximately 4 volts when zero to full scale pressure is applied to the sensor. the 4 volt swing in signal may vary slightly from sensor to sensor and can also vary due to resistor tolerances in the analog circuitry. jumpers j4 through j7 may be placed in various configurations to compensate for these variations (see table 3). f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3248 motorola sensor device data www.motorola.com/semiconductors + + + + pd0 tp1 +5 v 1n914 4.7k r4 8 10 9 r5 2k r6 2k 14 12 13 u1a u1c u1d u1b 3 2 11 1 976 r9 1k r10 340 r7 r8 23.7 +8 +8 14 23 xdcr1 121 r2 200 r3 6.98k r1 5 6 4 7 +12 v mc33274 d2 j8 is installed for the mpx2010 only j8 figure 3. figure 4. analog interface referring to figure 4, most of the amplification of the voltage from the pressure sensor is provided by u1a which is configured as a differential amplifier. u1b serves as a unity gain buffer in order to keep any current that flows through r2 (and r3) from being fed back into the sensor's negative output. with zero pressure applied to the sensor, the differential voltage from pin 2 to pin 4 of the sensor is zero or very close to zero volts. the common mode, or the voltage measured between pins 2 or 4 to ground, is equal to approximately one half of the voltage applied to the sensor, or 4 volts. the zero pressure output voltage at pin 7 of u1a will then be 4 volts because pin 1 of u1b is also at 4 volts, creating a zero bias between pins 5 and 6 of u1a. the four volt zero pressure output will then be level shifted to the desired zero pressure offset voltage (approximately 0.7 volts) by u1c and u1d. to further explain the operation of the level shifting circuitry, refer again to figure 4. assuming zero pressure is applied to the sensor and the common mode voltage from the sensor is 4 volts, the voltage applied to pin 12 of u1d will be 4 volts, implying pin 13 will be at 4 volts. the gain of amplifier u1d will be (r10/(r8+r9)) +1 or a gain of 2. r7 will inject a v offset (0.7 volts) into amplifier u1d, thus causing the output at u1d pin 14 to be 7.3 = (4 volts @ u1d pin 12 2) 0.7 volts. the gain of u1c is also set at 2 ((r5/r6)+1). with 4 volts applied to pin 10 of u1c, its output at u1c pin 8 will be 0.7 = ((4 volts @ u1c pin 10 2) 7.3 volts). for this scheme to work properly, amplifiers u1c and u1d must have a gain of 2 and the output of u1d must be shifted down by the v offset provided by r7. in this system, the 0.7 volts v offset was arbitrarily picked and could have been any voltage greater than the v sat of the op amp being used. the system software will take in account any variations of v offset as it assumes no pressure is applied to the sensor at system power up. the gain of the analog circuit is approximately 117. with the values shown in figure 4, the gain of 117 will provide a span of approximately 4 volts on u1c pin 8 when the pressure sensor and the 8 volt fixed voltage regulator are at their maximum output voltage tolerance. all of the sensors listed in table 1 with the exception of the mpx2010dp output approximately 33 mv when full scale pressure is applied. when the mpx2010dp sensor is used, its full scale sensor differential output is approximately 20 mv. j8 must be installed to increase the gain of the analog circuit to still provide the 4 volts span out of u1c pin 8 with a 20 mv differential from the sensor. diode d2 is used to protect the microprocessor's a/d input if the output from u1c exceeds 5.6 volts. r4 is used to provide current limiting into d4 under failure or overvoltage conditions. software the source code, compiled listing, and srecord output for the software used in this system are available on the motorola freeware bulletin board service in the mcu directory under the filename devb158.arc. to access the bulletin board, you must have a telephone line, a 300, 1200 or 2400 baud modem and a personal computer. the modem must be compatible with the bell 212a standard. call (512) 8913733 to access the bulletin board service. figure 5 is a flowchart for the program that controls the system. the software for the system consists of a number of modules. their functions provide the capability for system calibration as well as displaying the pressure input to the mpx2000 series pressure sensor. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3249 motorola sensor device data www.motorola.com/semiconductors figure 5. devb158 software flowchart timer interrupt service timer registers setup counter for next interrupt service liquid crystal display return accumulate 100 a/d conversions compute input pressure convert to decimal/segment data place in result output buffer compute slope constant initialize display i/o ports initialize timer registers determine sensor type enable interrupts start the aco compiler used in this project was provided by byte craft ltd. (519) 8886911. a compiler listing of the program is included at the end of this document. the following is a brief explanation of the routines: delay() used to provide a software loop delay. read_a2d() performs 100 reads on the a/d converter on multiplexer channel 0 and returns the accumulation. fixcompare() services the internal timer for 15 ms. timer compare interrupts. timercmp() alternates the data and backplane inputs to the liquid crystal display. initio() sets up the microprocessor's i/o ports, timer and enables processor interrupts. adzero() this routine is called at powerup time. it delays to let the power supply and the transducer stabilize. it then calls aread_atod()o and saves the returned value as the sensors output voltage with zero pressure applied. cvt_bin_dec(unsigned long arg) this routine converts the unsigned binary argument passed in aargo to a five digit decimal number in an array called adigit.o it then uses the decimal results for each digit as an index into a table that converts the decimal number into a segment pattern for the display. this is then output to the display. display_psi() this routine is called from amain()o never to return. the a/d converter routine is called, the pressure is calculated based on the type sensor detected and the pressure applied to the sensor is displayed. the loop then repeats. sensor_type() this routine determines the type of sensor from reading j1 to j3, setting the full scale pressure for that particular sensor in a variable for use by display_psi(). sensor_slope() this routine determines the slope constant to be used by display_psi() for engineering units output. main() this is the main routine called from reset. it calls ainitio()o to setup the system's i/o. adisplay_psi()o is called to compute and display the pressure applied to the sensor. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3250 motorola sensor device data www.motorola.com/semiconductors 6805 'c' compiler v3.48 16oct1991 page 1 #pragma option f0; /* the following 'c' source code is written for the devb158 evaluation board. it was compiled with a compiler courtesy of: byte craft ltd. 421 king st. waterloo, ontario canada n2j 4e4 (519)8886911 some source code changes may be necessary for compilation with other compilers. bill lucas 2/5/92 motorola, sps revision history rev. 1.0 initial release 3/19/92 rev. 1.1 added additional decimal digit to the mpx2010 sensor. originally resolved the output to .1 psi. modified cvt_bin_dec to output psi resolved to .01 psi. wll 9/25/92 */ 0800 1700 #pragma memory romprog [5888] @ 0x0800 ; 0050 0096 #pragma memory rampage0 [150] @ 0x0050 ; /* vector assignments */ 1ffe #pragma vector __reset @ 0x1ffe ; 1ffc #pragma vector __swi @ 0x1ffc ; 1ffa #pragma vector irq @ 0x1ffa ; 1ff8 #pragma vector timercap @ 0x1ff8 ; 1ff6 #pragma vector timercmp @ 0x1ff6 ; 1ff4 #pragma vector timerov @ 0x1ff4 ; 1ff2 #pragma vector sci @ 0x1ff2 ; #pragma has stop ; #pragma has wait ; #pragma has mul ; /* register assignments for the 68hc705b5 microcontroller */ 0000 #pragma portrw porta @ 0x00; /* */ 0001 #pragma portrw portb @ 0x01; /* */ 0002 #pragma portrw portc @ 0x02; /* */ 0003 #pragma portrw portd @ 0x03; /* in , ,ss ,sck ,mosi ,miso,txd,rxd */ 0004 #pragma portrw ddra @ 0x04; /* data direction, port a */ 0005 #pragma portrw ddrb @ 0x05; /* data direction, port b */ 0006 #pragma portrw ddrc @ 0x06; /* data direction, port c (all output) */ 0007 #pragma portrw eeclk @ 0x07; /* eeprom/eclk cntl */ 0008 #pragma portrw addata @ 0x08; /* a/d data register */ 0009 #pragma portrw adstat @ 0x09; /* a/d stat/control */ 000a #pragma portrw plma @ 0x0a; /* pulse length modulation a */ 000b #pragma portrw plmb @ 0x0b; /* pulse length modulation b */ 000c #pragma portrw misc @ 0x0c; /* miscellaneous register */ 000d #pragma portrw scibaud @ 0x0d; /* sci baud rate register */ 000e #pragma portrw scicntl1 @ 0x0e; /* sci control 1 */ 000f #pragma portrw scicntl2 @ 0x0f; /* sci control 2 */ 0010 #pragma portrw scistat @ 0x10; /* sci status reg */ 0011 #pragma portrw scidata @ 0x11; /* sci data */ 0012 #pragma portrw tcr @ 0x12; /* icie,ocie,toie,0;0,0,iege,olvl */ 0013 #pragma portrw tsr @ 0x13; /* icf,ocf,tof,0; 0,0,0,0 */ 0014 #pragma portrw icaphi1 @ 0x14; /* input capture reg (hi0x14, lo0x15) */ 0015 #pragma portrw icaplo1 @ 0x15; /* input capture reg (hi0x14, lo0x15) */ 0016 #pragma portrw ocmphi1 @ 0x16; /* output compare reg (hi0x16, lo0x17) */ 0017 #pragma portrw ocmplo1 @ 0x17; /* output compare reg (hi0x16, lo0x17) */ 0018 #pragma portrw tcnthi @ 0x18; /* timer count reg (hi0x18, lo0x19) */ 0019 #pragma portrw tcntlo @ 0x19; /* timer count reg (hi0x18, lo0x19) */ 001a #pragma portrw aregnthi @ 0x1a; /* alternate count reg (hi$1a, lo$1b) */ 001b #pragma portrw aregntlo @ 0x1b; /* alternate count reg (hi$1a, lo$1b) */ 001c #pragma portrw icaphi2 @ 0x1c; /* input capture reg (hi0x1c, lo0x1d) */ 001d #pragma portrw icaplo2 @ 0x1d; /* input capture reg (hi0x1c, lo0x1d) */ 001e #pragma portrw ocmphi2 @ 0x1e; /* output compare reg (hi0x1e, lo0x1f) */ 001f #pragma portrw ocmplo2 @ 0x1f; /* output compare reg (hi0x1e, lo0x1f) */ f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3251 motorola sensor device data www.motorola.com/semiconductors 1efe 74 #pragma mor @ 0x1efe = 0x74; /* this disables the watchdog counter and does not add pulldown resistors on ports b and c */ /* put constants and variables here...they must be global */ /***************************************************************************/ 0800 fc 30 da 7a 36 6e e6 38 fe const char lcdtab[]={0xfc,0x30,0xda,0x7a,0x36,0x6e,0xe6,0x38,0xfe,0x3e }; 0809 3e /* lcd pattern table 0 1 2 3 4 5 6 7 8 9 */ 080a 27 10 03 e8 00 64 00 0a const long dectable[] = { 10000, 1000, 100, 10 }; 0050 0005 unsigned int digit[5]; /* buffer to hold results from cvt_bin_dec function */ 0812 00 96 00 4b 00 96 00 1e 00 const long type[] = { 150, 75, 150, 30, 103 }; 081b 67 /* mpx2010 mpx2050 mpx2100 mpx2200 mpx2700 the table above will cause the final results of the pressure to engineering units to display the 1.5, 7.3 and 15.0 devices with a decimal place in the tens position. the 30 and 103 psi devices will display in integer units. */ const long slope_const[]={ 450,418,423,427,432,436,441,445,454,459, 081c 01 c2 01 a2 01 a7 01 ab 01 463,468,472,477,481,450 }; 0825 b0 01 b4 01 b9 01 bd 01 c6 082e 01 cb 01 cf 01 d4 01 d8 01 0837 dd 01 e1 01 c2 0000 registera areg; /* processor's a register */ 0055 long atodtemp; /* temp to accumulate 100 a/d readings for smoothing */ 0059 long slope; /* multiplier for adc to engineering units conversion */ 005b int adcnt; /* a/d converter loop counter */ 005c long xdcr_offset; /* initial xdcr offset */ 005e long sensor_model; /* installed sensor based on j1..j3 */ 0060 int sensor_index; /* determine the location of the decimal pt. */ 0061 0063 unsigned long i,j; /* counter for loops */ 0065 unsigned int k; /* misc variable */ struct bothbytes { int hi; { int lo; }; union isboth 0066 0002 { long l; 0066 0002 struct bothbytes b; 0066 0002 }; 0066 0002 union isboth q; /* used for timer setup */ /***************************************************************************/ /* variables for add32 */ 0068 0004 unsigned long sum[2]; /* result */ 006c 0004 unsigned long addend[2]; /* one input */ 0070 0004 unsigned long augend[2]; /* second input */ /* variables for sub32 */ 0074 0004 unsigned long minue[2]; /* minuend */ 0078 0004 unsigned long subtra[2]; /* subtrahend */ 007c 0004 unsigned long diff[2]; /* difference */ /* variables for mul32 */ 0080 0004 unsigned long multp[2]; /* multiplier */ 0084 0004 unsigned long mtemp[2]; /* high order 4 bytes at return */ 0088 0004 unsigned long mulcan[2]; /* multiplicand at input, low 4 bytes at return */ f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3252 motorola sensor device data www.motorola.com/semiconductors /* variables for div32 */ 008c 0004 unsigned long dvdnd[2]; /* dividend */ 0090 0004 unsigned long dvsor[2]; /* divisor */ 0094 0004 unsigned long quo[2]; /* quotient */ 0098 unsigned int cnt; /* loop counter */ /* the code starts here */ /***************************************************************************/ void add32() { #asm ** * add two 32bit values. * inputs: * addend: addend[0..3] high order byte is addend+0 * augend: augend[0..3] high order byte is augend+0 * output: * sum: sum[0..3] high order byte is sum+0 ** * 083c b6 6f lda addend+3 low byte 083e bb 73 add augend+3 0840 b7 6b sta sum+3 0842 b6 6e lda addend+2 medium low byte 0844 b9 72 adc augend+2 0846 b7 6a sta sum+2 0848 b6 6d lda addend+1 medium high byte 084a b9 71 adc augend+1 084c b7 69 sta sum+1 084e b6 6c lda addend high byte 0850 b9 70 adc augend 0852 b7 68 sta sum 0854 81 rts done * #endasm 0855 81 rts } void sub32() { #asm ** * subtract two 32bit values. * input: * minuend: minue[0..3] * subtrahend: subtra[0..3] * output: * difference: diff[1..0] ** * 0856 b6 77 lda minue+3 low byte 0858 b0 7b sub subtra+3 085a b7 7f sta diff+3 085c b6 76 lda minue+2 medium low byte 085e b2 7a sbc subtra+2 0860 b7 7e sta diff+2 0862 b6 75 lda minue+1 medium high byte 0864 b2 79 sbc subtra+1 0866 b7 7d sta diff+1 0868 b6 74 lda minue high byte 086a b2 78 sbc subtra 086c b7 7c sta diff 086e 81 rts done * #endasm 086f 81 rts } void mul32() { #asm ** * multiply 32bit value by a 32bit value * * * input: f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3253 motorola sensor device data www.motorola.com/semiconductors * multiplier: multp[0..3] * multiplicand: mulcan[0..3] * output: * product: mtemp[0..3] and mulcan[0..3] mtemp[0] is the high * order byte and mulcan[3] is the low order byte * * this routine does not use the mul instruction for the sake of users not * using the hc(7)05 series processors. ** * * 0870 ae 20 ldx #32 loop counter 0872 3f 84 clr mtemp cleanup for result 0874 3f 85 clr mtemp+1 * 0876 3f 86 clr mtemp+2 * 0878 3f 87 clr mtemp+3 * 087a 36 88 ror mulcan low but to carry, the rest one to the right 087c 36 89 ror mulcan+1 * 087e 36 8a ror mulcan+2 * 0880 36 8b ror mulcan+3 * 0882 24 18 mnext bcc rotate if carry is set, do the add 0884 b6 87 lda mtemp+3 * 0886 bb 83 add multp+3 * 0888 b7 87 sta mtemp+3 * 088a b6 86 lda mtemp+2 * 088c b9 82 adc multp+2 * 088e b7 86 sta mtemp+2 * 0890 b6 85 lda mtemp+1 * 0892 b9 81 adc multp+1 * 0894 b7 85 sta mtemp+1 * 0896 b6 84 lda mtemp * 0898 b9 80 adc multp * 089a b7 84 sta mtemp * 089c 36 84 rotate ror mtemp else: shift low bit to carry, the rest to the right 089e 36 85 ror mtemp+1 * 08a0 36 86 ror mtemp+2 * 08a2 36 87 ror mtemp+3 * 08a4 36 88 ror mulcan * 08a6 36 89 ror mulcan+1 * 08a8 36 8a ror mulcan+2 * 08aa 36 8b ror mulcan+3 * 08ac 5a dex bump the counter down 08ad 26 d3 bne mnext done yet ? 08af 81 rts done #endasm 08b0 81 rts } void div32() { #asm * ** * divide 32 bit by 32 bit unsigned integer routine * * input: * dividend: dvdnd [+0..+3] high order byte is dvnd+0 * divisor: dvsor [+0..+3] high order byte is dvsor+0 * output: * quotient: quo [+0..+3] high order byte is quo+0 ** * 08b1 3f 94 clr quozero result registers 08b3 3f 95 clr quo+1 * 08b5 3f 96 clr quo+2 * 08b7 3f 97 clr quo+3 * 08b9 a6 01 lda #1 initial loop count 08bb 3d 90 tst dvsor if the high order bit is set..no need to shift dvsor 08bd 2b 0f bmi div153 * 08bf 4c div151 inca bump the loop counter 08c0 38 93 asl dvsor+3 now shift the divisor until the high order bit = 1 08c2 39 92 rol dvsor+2 08c4 39 91 rol dvsor+1 * 08c6 39 90 rol dvsor * 08c8 2b 04 bmi div153 done if high order bit = 1 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3254 motorola sensor device data www.motorola.com/semiconductors 08ca a1 21 cmp #33 have we shifted all possible bits in the dvsor yet ? 08cc 26 f1 bne div151 no * 08ce b7 98 div153 sta cnt save the loop counter so we can do the divide * 08d0 b6 8f div163 lda dvdnd+3 sub 32 bit divisor from dividend 08d2 b0 93 sub dvsor+3 * 08d4 b7 8f sta dvdnd+3 * 08d6 b6 8e lda dvdnd+2 * 08d8 b2 92 sbc dvsor+2 * 08da b7 8e sta dvdnd+2 * 08dc b6 8d lda dvdnd+1 * 08de b2 91 sbc dvsor+1 * 08e0 b7 8d sta dvdnd+1 * 08e2 b6 8c lda dvdnd * 08e4 b2 90 sbc dvsor * 08e6 b7 8c sta dvdnd * 08e8 24 1b bcc div165 carry is clear if dvsor was larger than dvdnd * 08ea b6 8f lda dvdnd+3 add the divisor back...was larger than the dividend 08ec bb 93 add dvsor+3 * 08ee b7 8f sta dvdnd+3 * 08f0 b6 8e lda dvdnd+2 * 08f2 b9 92 adc dvsor+2 * 08f4 b7 8e sta dvdnd+2 * 08f6 b6 8d lda dvdnd+1 * 08f8 b9 91 adc dvsor+1 * 08fa b7 8d sta dvdnd+1 * 08fc b6 8c lda dvdnd * 08fe b9 90 adc dvsor * 0900 b7 8c sta dvdnd * 0902 98 clc this will clear the respective bit in quo due to * the need to add dvsor back to dvnd 0903 20 01 bra div167 0905 99 div165 sec this will set the respective bit in quo 0906 39 97 div167 rol quo+3 set or clear the low order bit in quo based on above 0908 39 96 rol quo+2 * 090a 39 95 rol quo+1 * 090c 39 94 rol quo * 090e 34 90 lsr dvsor divide the divisor by 2 0910 36 91 ror dvsor+1 * 0912 36 92 ror dvsor+2 * 0914 36 93 ror dvsor+3 * 0916 3a 98 dec cnt bump the loop counter down 0918 26 b6 bne div163 finished yet ? 091a 81 rtsyes * #endasm 091b 81 rts } /***************************************************************************/ /* these interrupts are not used...give them a graceful return if for some reason one occurs */ 1ffc 09 1c __swi(){} 091c 80 rti 1ffa 09 1d irq(){} 091d 80 rti 1ff8 09 1e timercap(){} 091e 80 rti 1ff4 09 1f timerov(){} 091f 80 rti 1ff2 09 20 sci(){} 0920 80 rti /***************************************************************************/ void sensor_type() { 0921 b6 03 lda $03 k = portd & 0x0e; /* we only care about bits 1..3 */ 0923 a4 0e and #$0e 0925 b7 65 sta $65 0927 34 65 lsr $65 k = k >> 1; /* right justify the variable */ 0929 b6 65 lda $65 if ( k > 4 ) 092b a1 04 cmp #$04 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3255 motorola sensor device data www.motorola.com/semiconductors 092d 23 0c bls $093b { /* we have a setup error in wire jumpers j1 j3 */ 092f 3f 02 clr $02 portc = 0; /* */ 0931 a6 6e lda #$6e portb = 0x6e; /* s */ 0933 b7 01 sta $01 0935 a6 ce lda #$ce porta = 0xce; /* e */ 0937 b7 00 sta $00 0939 20 fe bra $0939 while(1); } 093b b6 65 lda $65 sensor_index = k; 093d b7 60 sta $60 093f 97 tax sensor_model = type[k]; 0940 58 lslx 0941 d6 08 12 lda $0812,x 0944 b7 5e sta $5e 0946 d6 08 13 lda $0813,x 0949 b7 5f sta $5f 094b 81 rts } /***************************************************************************/ void sensor_slope() { 094c b6 03 lda $03 k=portd & 0xf0; /* we only care about bits 4..7 */ 094e a4 f0 and #$f0 0950 b7 65 sta $65 0952 34 65 lsr $65 k = k >> 4; /* right justify the variable */ 0954 34 65 lsr $65 0956 34 65 lsr $65 0958 34 65 lsr $65 095a be 65 ldx $65 slope = slope_const[k]; 095c 58 lslx 095d d6 08 1c lda $081c,x 0960 b7 59 sta $59 0962 d6 08 1d lda $081d,x 0965 b7 5a sta $5a 0967 81 rts } /***************************************************************************/ void delay(void) /* just hang around for a while */ { 0968 3f 62 clr $62 for (i=0; i<20000; ++i); 096a 3f 61 clr $61 096c b6 62 lda $62 096e a0 20 sub #$20 0970 b6 61 lda $61 0972 a2 4e sbc #$4e 0974 24 08 bcc $097e 0976 3c 62 inc $62 0978 26 02 bne $097c 097a 3c 61 inc $61 097c 20 ee bra $096c 097e 81 rts } /***************************************************************************/ read_a2d(void) { /* read the a/d converter on channel 5 and accumulate the result in atodtemp */ 097f 3f 56 clr $56 atodtemp=0; /* zero for accumulation */ 0981 3f 55 clr $55 0983 3f 5b clr $5b for ( adcnt = 0 ; adcnt<100; ++adcnt) /* do 100 a/d conversions */ 0985 b6 5b lda $5b 0987 a8 80 eor #$80 0989 a1 e4 cmp #$e4 098b 24 21 bcc $09ae { 098d a6 20 lda #$20 adstat = 0x20; /* convert on channel 0 */ 098f b7 09 sta $09 0991 0f 09 fd brclr 7,$09,$0991 while (!(adstat & 0x80)); /* wait for a/d to complete */ 0994 b6 08 lda $08 atodtemp = addata + atodtemp; 0996 3f 57 clr $57 0998 b7 58 sta $58 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3256 motorola sensor device data www.motorola.com/semiconductors 099a bb 56 add $56 099c b7 58 sta $58 099e b6 57 lda $57 09a0 b9 55 adc $55 09a2 b7 57 sta $57 09a4 b7 55 sta $55 09a6 b6 58 lda $58 09a8 b7 56 sta $56 } 09aa 3c 5b inc $5b 09ac 20 d7 bra $0985 09ae b6 56 lda $56 atodtemp = atodtemp/100; 09b0 b7 58 sta $58 09b2 b6 55 lda $55 09b4 b7 57 sta $57 09b6 3f 9a clr $9a 09b8 a6 64 lda #$64 09ba b7 9b sta $9b 09bc cd 0b f1 jsr $0bf1 09bf cd 0c 22 jsr $0c22 09c2 bf 55 stx $55 09c4 b7 56 sta $56 09c6 81 rts return atodtemp; } /***************************************************************************/ void fixcompare (void) /* setsup the timer compare for the next interrupt */ { 09c7 b6 18 lda $18 q.b.hi =tcnthi; 09c9 b7 66 sta $66 09cb b6 19 lda $19 q.b.lo = tcntlo; 09cd b7 67 sta $67 09cf ab 4c add #$4c q.l +=7500; /* ((4mhz xtal/2)/4) = counter period = 2us.*7500 = 15ms. */ 09d1 b7 67 sta $67 09d3 b6 66 lda $66 09d5 a9 1d adc #$1d 09d7 b7 66 sta $66 09d9 b7 16 sta $16 ocmphi1 = q.b.hi; 09db b6 13 lda $13 areg=tsr; /* dummy read */ 09dd b6 67 lda $67 ocmplo1 = q.b.lo; 09df b7 17 sta $17 09e1 81 rts } /***************************************************************************/ void timercmp (void) /* timer service module */ 1ff6 09 e2 { 09e2 33 02 com $02 portc =~ portc; /* service the lcd by inverting the ports */ 09e4 33 01 com $01 portb =~ portb; 09e6 33 00 com $00 porta =~ porta; 09e8 ad dd bsr $09c7 fixcompare(); 09ea 80 rti } /***************************************************************************/ void adzero(void) /* called by initio() to save initial xdcr's zero pressure offset voltage output */ { 09eb 3f 64 clr $64 for ( j=0; j<20; ++j) /* give the sensor time to owarmupo and the 09ed 3f 63 clr $63 09ef b6 64 lda $64 09f1 a0 14 sub #$14 09f3 b6 63 lda $63 09f5 a2 00 sbc #$00 09f7 24 0b bcc $0a04 power supply time to settle down */ { 09f9 cd 09 68 jsr $0968 delay(); } 09fc 3c 64 inc $64 09fe 26 02 bne $0a02 0a00 3c 63 inc $63 0a02 20 eb bra $09ef 0a04 cd 09 7f jsr $097f xdcr_offset = read_a2d(); f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3257 motorola sensor device data www.motorola.com/semiconductors 0a07 3f 5c clr $5c 0a09 b7 5d sta $5d 0a0b 81 rts } /***************************************************************************/ void initio (void) /* setup the i/o */ { 0a0c a6 20 lda #$20 adstat = 0x20; /* powerup the a/d */ 0a0e b7 09 sta $09 0a10 3f 02 clr $02 porta = portb = portc = 0; 0a12 3f 01 clr $01 0a14 3f 00 clr $00 0a16 a6 ff lda #$ff ddra = ddrb = ddrc = 0xff; 0a18 b7 06 sta $06 0a1a b7 05 sta $05 0a1c b7 04 sta $04 0a1e b6 13 lda $13 areg=tsr; /* dummy read */ 0a20 3f 1e clr $1e ocmphi1 = ocmphi2 = 0; 0a22 3f 16 clr $16 0a24 b6 1f lda $1f areg = ocmplo2; /* clear out output compare 2 if it happens to be set */ 0a26 ad 9f bsr $09c7 fixcompare(); /* setup for the first timer interrupt */ 0a28 a6 40 lda #$40 tcr = 0x40; 0a2a b7 12 sta $12 0a2c 9a cli cli; /* let the interrupts begin ! */ /* write cal to the display */ 0a2d a6 cc lda #$cc portc = 0xcc; /* c */ 0a2f b7 02 sta $02 0a31 a6 be lda #$be portb = 0xbe; /* a */ 0a33 b7 01 sta $01 0a35 a6 c4 lda #$c4 porta = 0xc4; /* l */ 0a37 b7 00 sta $00 0a39 cd 09 21 jsr $0921 sensor_type(); /* get the model of the sensor based on j1..j3 */ 0a3c ad ad bsr $09eb adzero(); /* auto zero */ 0a3e 81 rts } /***************************************************************************/ void cvt_bin_dec(unsigned long arg) /* first converts the argument to a five digit decimal value. the msd is in the lowest address. then leading zero suppress the value and write it to the display ports. the argument value is 0..65535 decimal. */ 009d { 0a3f bf 9d stx $9d 0a41 b7 9e sta $9e 009f char i; 00a0 unsigned long l; 0a43 3f 9f clr $9f for ( i=0; i < 5; ++i ) 0a45 b6 9f lda $9f 0a47 a1 05 cmp #$05 0a49 24 07 bcc $0a52 { 0a4b 97 tax digit[i] = 0x0; /* put blanks in all digit positions */ 0a4c 6f 50 clr $50,x } 0a4e 3c 9f inc $9f 0a50 20 f3 bra $0a45 0a52 3f 9f clr $9f for ( i=0; i < 4; ++i ) 0a54 b6 9f lda $9f 0a56 a1 04 cmp #$04 0a58 24 7a bcc $0ad4 { 0a5a 97 tax if ( arg >= dectable [i] ) 0a5b 58 lslx 0a5c d6 08 0b lda $080b,x 0a5f b0 9e sub $9e 0a61 b7 58 sta $58 0a63 b6 9d lda $9d 0a65 a8 80 eor #$80 0a67 b7 57 sta $57 0a69 d6 08 0a lda $080a,x 0a6c a8 80 eor #$80 0a6e b2 57 sbc $57 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3258 motorola sensor device data www.motorola.com/semiconductors 0a70 ba 58 ora $58 0a72 22 5c bhi $0ad0 { 0a74 be 9f ldx $9f l = dectable[i]; 0a76 58 lslx 0a77 d6 08 0a lda $080a,x 0a7a b7 a0 sta $a0 0a7c d6 08 0b lda $080b,x 0a7f b7 a1 sta $a1 0a81 b6 9e lda $9e digit[i] = arg / l; 0a83 b7 58 sta $58 0a85 b6 9d lda $9d 0a87 b7 57 sta $57 0a89 b6 a0 lda $a0 0a8b b7 9a sta $9a 0a8d b6 a1 lda $a1 0a8f b7 9b sta $9b 0a91 cd 0b f1 jsr $0bf1 0a94 cd 0c 22 jsr $0c22 0a97 bf 57 stx $57 0a99 b7 58 sta $58 0a9b be 9f ldx $9f 0a9d e7 50 sta $50,x 0a9f be 9f ldx $9f arg = arg(digit[i] * l); 0aa1 e6 50 lda $50,x 0aa3 3f 57 clr $57 0aa5 b7 58 sta $58 0aa7 b6 a0 lda $a0 0aa9 b7 9a sta $9a 0aab b6 a1 lda $a1 0aad b7 9b sta $9b 0aaf cd 0b d2 jsr $0bd2 0ab2 bf 57 stx $57 0ab4 b7 58 sta $58 0ab6 33 57 com $57 0ab8 30 58 neg $58 0aba 26 02 bne $0abe 0abc 3c 57 inc $57 0abe b6 58 lda $58 0ac0 bb 9e add $9e 0ac2 b7 58 sta $58 0ac4 b6 57 lda $57 0ac6 b9 9d adc $9d 0ac8 b7 57 sta $57 0aca b7 9d sta $9d 0acc b6 58 lda $58 0ace b7 9e sta $9e } } 0ad0 3c 9f inc $9f 0ad2 20 80 bra $0a54 0ad4 b6 9e lda $9e digit[i] = arg; 0ad6 b7 58 sta $58 0ad8 b6 9d lda $9d 0ada b7 57 sta $57 0adc be 9f ldx $9f 0ade b6 58 lda $58 0ae0 e7 50 sta $50,x /* now zero suppress and send the lcd pattern to the display */ 0ae2 9b sei sei; 0ae3 3d 52 tst $52 if ( digit[2] == 0 ) /* leading zero suppression */ 0ae5 26 04 bne $0aeb 0ae7 3f 02 clr $02 portc = 0; 0ae9 20 07 bra $0af2 else 0aeb be 52 ldx $52 portc = ( lcdtab[digit[2]] ); /* 100's digit */ 0aed d6 08 00 lda $0800,x 0af0 b7 02 sta $02 0af2 3d 52 tst $52 if ( digit[2] == 0 && digit[3] == 0 ) 0af4 26 08 bne $0afe 0af6 3d 53 tst $53 0af8 26 04 bne $0afe 0afa 3f 01 clr $01 portb=0; 0afc 20 07 bra $0b05 else 0afe be 53 ldx $53 portb = ( lcdtab[digit[3]] ); /* 10's digit */ 0b00 d6 08 00 lda $0800,x f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3259 motorola sensor device data www.motorola.com/semiconductors 0b03 b7 01 sta $01 0b05 be 54 ldx $54 porta = ( lcdtab[digit[4]] ); /* 1's digit */ 0b07 d6 08 00 lda $0800,x 0b0a b7 00 sta $00 /* place the decimal point only if the sensor is 15 psi or 7.5 psi */ 0b0c b6 60 lda $60 if ( sensor_index < 3 ) 0b0e a8 80 eor #$80 0b10 a1 83 cmp #$83 0b12 24 08 bcc $0b1c 0b14 be 54 ldx $54 porta = ( lcdtab[digit[4]]+1 ); /* add the decimal point to the lsd */ 0b16 d6 08 00 lda $0800,x 0b19 4c inca 0b1a b7 00 sta $00 0b1c 3d 60 tst $60 if(sensor_index ==0) /* special case */ 0b1e 26 0f bne $0b2f { 0b20 be 54 ldx $54 porta = ( lcdtab[digit[4]] ); /* get rid of the decimal at lsd */ 0b22 d6 08 00 lda $0800,x 0b25 b7 00 sta $00 0b27 be 53 ldx $53 portb = ( lcdtab[digit[3]]+1 ); /* decimal point at middle digit */ 0b29 d6 08 00 lda $0800,x 0b2c 4c inca 0b2d b7 01 sta $01 } 0b2f 9a cli cli; 0b30 cd 09 68 jsr $0968 delay(); 0b33 81 rts } /****************************************************************/ void display_psi(void) /* at powerup it is assumed that the pressure or vacuum port of the sensor is open to atmosphere. the code in initio() delays for the sensor and power supply to stabilize. one hundred a/d conversions are averaged. that result is called xdcr_offset. this routine calls the a/d routine which performs one hundred conversions, divides the result by 100 and returns the value. if the value returned is less than or equal to the xdcr_offset, the value of xdcr_offset is substituted. if the value returned is greater than xdcr_offset, xdcr_offset is subtracted from the returned value. */ { while(1) { 0b34 cd 09 7f jsr $097f atodtemp = read_a2d(); /* atodtemp = raw a/d ( 0..255 ) */ 0b37 3f 55 clr $55 0b39 b7 56 sta $56 0b3b b0 5d sub $5d if ( atodtemp <= xdcr_offset ) 0b3d b7 58 sta $58 0b3f b6 5c lda $5c 0b41 a8 80 eor #$80 0b43 b7 57 sta $57 0b45 b6 55 lda $55 0b47 a8 80 eor #$80 0b49 b2 57 sbc $57 0b4b ba 58 ora $58 0b4d 22 08 bhi $0b57 0b4f b6 5c lda $5c atodtemp = xdcr_offset; 0b51 b7 55 sta $55 0b53 b6 5d lda $5d 0b55 b7 56 sta $56 0b57 b6 56 lda $56 atodtemp = xdcr_offset; /* remove the offset */ 0b59 b0 5d sub $5d 0b5b b7 56 sta $56 0b5d b6 55 lda $55 0b5f b2 5c sbc $5c 0b61 b7 55 sta $55 0b63 cd 09 4c jsr $094c sensor_slope(); /* establish the slope constant for this output */ 0b66 b6 56 lda $56 atodtemp *= sensor_model; 0b68 b7 58 sta $58 0b6a b6 55 lda $55 0b6c b7 57 sta $57 0b6e b6 5e lda $5e f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3260 motorola sensor device data www.motorola.com/semiconductors 0b70 b7 9a sta $9a 0b72 b6 5f lda $5f 0b74 b7 9b sta $9b 0b76 cd 0b d2 jsr $0bd2 0b79 bf 55 stx $55 0b7b b7 56 sta $56 0b7d 3f 89 clr $89 multp[0] = mulcan[0] = 0; 0b7f 3f 88 clr $88 0b81 3f 81 clr $81 0b83 3f 80 clr $80 0b85 9f txa multp[1] = atodtemp; 0b86 b7 82 sta $82 0b88 b6 56 lda $56 0b8a b7 83 sta $83 0b8c b6 59 lda $59 mulcan[1] = slope; 0b8e b7 8a sta $8a 0b90 b6 5a lda $5a 0b92 b7 8b sta $8b 0b94 cd 08 70 jsr $0870 mul32(); /* analog value * slope based on j1 through j3 */ 0b97 3f 90 clr $90 dvsor[0] = 1; /* now divide by 100000 */ 0b99 a6 01 lda #$01 0b9b b7 91 sta $91 0b9d a6 86 lda #$86 dvsor[1] = 0x86a0; 0b9f b7 92 sta $92 0ba1 a6 a0 lda #$a0 0ba3 b7 93 sta $93 0ba5 b6 88 lda $88 dvdnd[0] = mulcan[0]; 0ba7 b7 8c sta $8c 0ba9 b6 89 lda $89 0bab b7 8d sta $8d 0bad b6 8a lda $8a dvdnd[1] = mulcan[1]; 0baf b7 8e sta $8e 0bb1 b6 8b lda $8b 0bb3 b7 8f sta $8f 0bb5 cd 08 b1 jsr $08b1 div32(); 0bb8 b6 96 lda $96 atodtemp = quo[1]; /* convert to psi */ 0bba b7 55 sta $55 0bbc b6 97 lda $97 0bbe b7 56 sta $56 0bc0 be 55 ldx $55 cvt_bin_dec( atodtemp ); /* convert to decimal and display */ 0bc2 cd 0a 3f jsr $0a3f 0bc5 cc 0b 34 jmp $0b34 } 0bc8 81 rts } /***************************************************************************/ void main() { 0bc9 cd 0a 0c jsr $0a0c initio(); /* setup the processor's i/o */ 0bcc cd 0b 34 jsr $0b34 display_psi(); 0bcf 20 fe bra $0bcf while(1); /* should never get back to here */ 0bd1 81 rts } 0bd2 be 58 ldx $58 0bd4 b6 9b lda $9b 0bd6 42 mul 0bd7 b7 a4 sta $a4 0bd9 bf a5 stx $a5 0bdb be 57 ldx $57 0bdd b6 9b lda $9b 0bdf 42 mul 0be0 bb a5 add $a5 0be2 b7 a5 sta $a5 0be4 be 58 ldx $58 0be6 b6 9a lda $9a 0be8 42 mul 0be9 bb a5 add $a5 0beb b7 a5 sta $a5 0bed 97 tax 0bee b6 a4 lda $a4 0bf0 81 rts 0bf1 3f a4 clr $a4 0bf3 5f clrx 0bf4 3f a2 clr $a2 0bf6 3f a3 clr $a3 0bf8 5c incx 0bf9 38 58 lsl $58 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3261 motorola sensor device data www.motorola.com/semiconductors 0bfb 39 57 rol $57 0bfd 39 a2 rol $a2 0bff 39 a3 rol $a3 0c01 b6 a2 lda $a2 0c03 b0 9b sub $9b 0c05 b7 a2 sta $a2 0c07 b6 a3 lda $a3 0c09 b2 9a sbc $9a 0c0b b7 a3 sta $a3 0c0d 24 0d bcc $0c1c 0c0f b6 9b lda $9b 0c11 bb a2 add $a2 0c13 b7 a2 sta $a2 0c15 b6 9a lda $9a 0c17 b9 a3 adc $a3 0c19 b7 a3 sta $a3 0c1b 99 sec 0c1c 59 rolx 0c1d 39 a4 rol $a4 0c1f 24 d8 bcc $0bf9 0c21 81 rts 0c22 53 comx 0c23 9f txa 0c24 be a4 ldx $a4 0c26 53 comx 0c27 81 rts 1ffe 0b c9 symbol table label value label value label value label value addend 006c | augend 0070 | cnt 0098 | diff 007c div151 08bf | div153 08ce | div163 08d0 | div165 0905 div167 0906 | dvdnd 008c | dvsor 0090 | irq 091d minue 0074 | mnext 0882 | mtemp 0084 | mulcan 0088 multp 0080 | quo 0094 | rotate 089c | sci 0920 subtra 0078 | sum 0068 | timercap 091e | timercmp 09e2 timerov 091f | __ldiv 0bf1 | __longix 009a | __main 0bc9 __mul 0000 | __mul16x16 0bd2 | __rdiv 0c22 | __reset 1ffe __startup 0000 | __stop 0000 | __swi 091c | __wait 0000 __longac 0057 | adcnt 005b | add32 083c | addata 0008 adstat 0009 | adzero 09eb | aregnthi 001a | aregntlo 001b arg 009d | atodtemp 0055 | b 0000 | bothbytes 0002 cvt_bin_dec 0a3f | ddra 0004 | ddrb 0005 | ddrc 0006 dectable 080a | delay 0968 | digit 0050 | display_psi 0b34 div32 08b1 | eeclk 0007 | fixcompare 09c7 | hi 0000 i 0061 | icaphi1 0014 | icaphi2 001c | icaplo1 0015 icaplo2 001d | initio 0a0c | isboth 0002 | j 0063 k 0065 | l 0000 | lcdtab 0800 | lo 0001 main 0bc9 | misc 000c | mul32 0870 | ocmphi1 0016 ocmphi2 001e | ocmplo1 0017 | ocmplo2 001f | plma 000a plmb 000b | porta 0000 | portb 0001 | portc 0002 portd 0003 | q 0066 | read_a2d 097f | scibaud 000d scicntl1 000e | scicntl2 000f | scidata 0011 | scistat 0010 sensor_index 0060 | sensor_model 005e | sensor_slope 094c | sensor_type 0921 slope 0059 | slope_const 081c | sub32 0856 | tcnthi 0018 tcntlo 0019 | tcr 0012 | tsr 0013 | type 0812 xdcr_offset 005c | memory usage map ('x' = used, '' = unused) 0800 : xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx 0840 : xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx 0880 : xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx 08c0 : xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx 0900 : xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx 0940 : xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx 0980 : xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx 09c0 : xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx 0a00 : xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx 0a40 : xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx 0a80 : xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx 0ac0 : xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3262 motorola sensor device data www.motorola.com/semiconductors 0b00 : xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx 0b40 : xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx 0b80 : xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx 0bc0 : xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx 0c00 : xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx xxxxxxxx 0c40 : 0c80 : 0cc0 : 1e00 : 1e40 : 1e80 : 1ec0 : x 1f00 : 1f40 : 1f80 : 1fc0 : xxxxxxxxxxxxxx all other memory blocks unused. errors : 0 warnings : 0 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3263 motorola sensor device data www.motorola.com/semiconductors prepared by: jeff baum discrete applications engineering introduction typically, a semiconductor pressure transducer converts applied pressure to a alowlevelo voltage signal. current technology enables this sensor output to be temperature compensated and amplified to higher voltage levels on a single silicon integrated circuit (ic). while onchip temperature compensation and signal conditioning certainly provide a significant amount of added value to the basic sensing device, one must also consider how this final output will be used and/or interfaced for further processing. in most sensing systems, the sensor signal will be input to additional analog circuitry, control logic, or a microcontroller unit (mcu). mcubased systems have become extremely cost effective. the level of intelligence which can be obtained for only a couple of dollars, or less, has made relatively simple 8bit microcontrollers the partner of choice for semiconductor pressure transducers. in order for the sensor to communicate its pressuredependent voltage signal to the microprocessor, the mcu must have an analogtodigital converter (a/d) as an onchip resource or an additional ic packaged a/d. in the latter case, the a/d must have a communications interface that is compatible with one of the mcu's communications protocols. mcu's are adept at detecting logiclevel transitions that occur at input pins designated for screening such events. as an alternative to the conventional a/d sensor/mcu interface, one can measure either a period (frequency) or pulse width of an incoming square or rectangular wave signal. common mcu timer subsystem clock frequencies permit temporal measurements with resolution of hundreds of nanoseconds. thus, one is capable of accurately measuring the the frequency output of a device that is interfaced to such a timer channel. if sensors can provide a frequency modulated signal that is linearly proportional to the applied pressure being measured, then an accurate, inexpensive (no a/d) mcubased sensor system is a viable solution to many challenging sensing applications. besides the inherent cost savings of such a system, this design concept offers additional benefits to remote sensing applications and sensing in electrically noisy environments. figure 1. devb160 frequency output sensor evb (board no longer available)
semiconductor application note rev 2 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3264 motorola sensor device data www.motorola.com/semiconductors the following sections will detail the design issues involved in such a system architecture, and will provide an example circuit which has been developed as an evaluation tool for frequency output pressure sensor applications. design considerations signal conditioning motorola's mpx2000 series sensors are temperature compensated and calibrated i.e. offset and fullscale span are precision trimmed pressure transducers. these sensors are available in fullscale pressure ranges from 10 kpa (1.5 psi) to 200 kpa (30 psi). although the specifications in the data sheets apply only to a 10 v supply voltage, the output of these devices is ratiometric with the supply voltage. at the absolute maximum supply voltage specified, 16 v, the sensor will produce a differential output voltage of 64 mv at the rated fullscale pressure of the given sensor. one exception to this is that the fullscale span of the mpx2010 (10 kpa sensor) will be only 40 mv due to a slightly lower sensitivity. since the maximum supply voltage produces the most output voltage, it is evident that even the best case scenario will require some signal conditioning to obtain a usable voltage level. many different ainstrumentationtypeo amplifier circuits can satisfy the signal conditioning needs of these devices. depending on the precision and temperature performance demanded by a given application, one can design an amplifier circuit using a wide variety of operational amplifier (op amp) ic packages with external resistors of various tolerances, or a precisiontrimmed integrated instrumentation amplifier ic. in any case, the usual goal is to have a singleended supply, arailtorailo output (i.e. use as much of the range from ground to the supply voltage as possible, without saturating the op amps). in addition, one may need the flexibility of performing zeropressure offset adjust and fullscale pressure calibration. the circuitry or device used to accomplish the voltagetofrequency conversion will determine if, how, and where calibration adjustments are needed. see evaluation board circuit description section for details. voltagetofrequency conversion since most semiconductor pressure sensors provide a voltage output, one must have a means of converting this voltage signal to a frequency that is proportional to the sensor output voltage. assuming the analog voltage output of the sensor is proportional to the applied pressure, the resultant frequency will be linearly related to the pressure being measured. there are many different timing circuits that can perform voltagetofrequency conversion. most of the asimpleo (relatively low number of components) circuits do not provide the accuracy or the stability needed for reliably encoding a signal quantity. fortunately, many voltagetofrequency (v/f) converter ic's are commercially available that will satisfy this function. switching time reduction one limitation of some v/f converters is the less than adequate switching transition times that effect the pulse or squarewave frequency signal. the required switching speed will be determined by the hardware used to detect the switching edges. the motorola family of microcontrollers have inputcapture functions that employ aschmitt triggerlikeo inputs with hysteresis on the dedicated input pins. in this case, slow rise and fall times will not cause an input capture pin to be in an indeterminate state during a transition. thus, cmos logic instability and significant timing errors will be prevented during slow transitions. since the sensor's frequency output may be interfaced to other logic configurations, a designer's main concern is to comply with a worstcase timing scenario. for highspeed cmos logic, the maximum rise and fall times are typically specified at several hundreds of nanoseconds. thus, it is wise to speed up the switching edges at the output of the v/f converter. a single smallsignal fet and a resistor are all that is required to obtain switching times below 100 ns. applications besides eliminating the need for an a/d converter, a frequency output is conducive to applications in which the sensor output must be transmitted over long distances, or when the presence of noise in the sensor environment is likely to corrupt an otherwise healthy signal. for sensor outputs encoded as a voltage, induced noise from electromagnetic fields will contaminate the true voltage signal. a frequency signal has greater immunity to these noise sources and can be effectively filtered in proximity to the mcu input. in other words, the frequency measured at the mcu will be the frequency transmitted at the output of a sensor located remotely. since highfrequency noise and 5060 hz line noise are the two most prominent sources for contamination of instrumentation signals, a frequency signal with a range in the low end of the khz spectrum is capable of being well filtered prior to being examined at the mcu. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3265 motorola sensor device data www.motorola.com/semiconductors table 1. specifications characteristics symbol min typ max units power supply voltage b + 10 30 volts full scale pressure p fs mpx2010 10 kpa mpx2050 50 kpa mpx2100 100 kpa mpx2200 200 kpa full scale output f fs 10 khz zero pressure offset f off 1 khz sensitivity s aout 9/p fs khz/kpa quiescent current i cc 55 ma evaluation board the following sections present an example of the signal conditioning, including frequency conversion, that was developed as an evaluation tool for the motorola mpx2000 series pressure sensors. a summary of the information required to use evaluation board number devb160 is presented as follows. description the evaluation board shown in figure 1 is designed to transduce pressure, vacuum or differential pressure into a singleended, ground referenced voltage that is then input to a voltagetofrequency converter. it nominally provides a 1 khz output at zero pressure and 10 khz at full scale pressure. zero pressure calibration is made with a trimpot that is located on the lower half of the left side of the board, while the full scale output can be calibrated via another trimpot just above the offset adjust. the board comes with an mpx2100dp sensor installed, but will accommodate any mpx2000 series sensor. one additional modification that may be required is that the gain of the circuit must be increased slightly when using an mpx2010 sensor. specifically, the resistor r5 must be increased from 7.5 k w to 12 k w . circuit description the following pin description and circuit operation corresponds to the schematic shown in figure 2. pinbypin description b + : input power is supplied at the b + terminal of connector cn1. minimum input voltage is 10 v and maximum is 30 v. f out : a logiclevel (5 v) frequency output is supplied at the out terminal (cn1). the nominal signal it provides is 1 khz at zero pressure and 10 khz at full scale pressure. zero pressure frequency is adjustable and set with r12. fullscale frequency is calibrated via r13. this output is designed to be directly connected to a microcontroller timer system inputcapture channel. gnd: the ground terminal on connector cn1 is intended for use as the power supply return and signal common. test point terminal tp3 is also connected to ground, for measurement convenience. tp1: test point 1 is connected to the final frequency output, f out . tp2: test point 2 is connected to the +5 v regulator output. it can be used to verify that this supply voltage is within its tolerance. tp3: test point 3 is the additional ground point mentioned above in the gnd description. tp4: test point 4 is connected to the +8 v regulator output. it can be used to verify that this supply voltage is within its tolerance. p1, p2: pressure and vacuum ports p1 and p2 protrude from the sensor on the right side of the board. pressure port p1 is on the top (marked side of package) and vacuum port p2, if present, is on the bottom. when the board is set up with a dual ported sensor (dp suffix), pressure applied to p1, vacuum applied to p2 or a differential pressure applied between the two all produce the same output voltage per kpa of input. neither port is labeled. absolute maximum differential pressure is 700 kpa. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3266 motorola sensor device data www.motorola.com/semiconductors figure 2. devb160 frequency output sensor evaluation board s1 1 3 2 on/off c1 1 f m 2 ground in out mc78l08acp u2 tp4 1 r8 620 d1 mv57124a 4 u1a mc33274 u1c 10 9 8 c4 0.1 f m r11 2 k 11 2 3 + r6 120 r5 7.5 k 6 5 7 u1b 12 13 r10 2 k r13 1 k r3 4.3 k fullscale c5 10 f m + tp3 tp1 gnd f b+ cn1 b+ + u1d r7 820 r9 1 k r4 1.5 k 1 2 3 4 fout logcom rt +v v ct ct v 8 7 6 5 c3 0.01 f m r2 1 k 2 3 1 tp2 c6 0.1 f m r1 240 u5 bs107a x1 mpx2100dp 4 1 2 3 c2 0.1 f m ad654 ground out in u4 mc78l05acp 3 1 + r12 200 offset + tantalum 1 2 3 14 w w w w w w w w w w w w out in ss cc w f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3267 motorola sensor device data www.motorola.com/semiconductors the following is a table of the components that are assembled on the devb160 frequency output sensor evaluation board. table 2. parts list designators quantity description manufacturer part number c1 1 1 m f capacitor c2 1 0.1 m f capacitor c3 1 0.01 m f capacitor c4 1 0.1 m f capacitor c5 1 10 m f cap+ tantalum c6 1 0.1 m f capacitor cn1 1 .15ls 3 term phx contact 1727023 d1 1 red led quality tech. mv57124a r1 1 240 w resistor r2, r9 2 1 k w resistor r3 1 4.3 k w resistor r4 1 1.5 k w resistor r5 1 7.5 k w resistor r6 1 120 w resistor r7 1 820 w resistor r8 1 620 w resistor r10, r11 2 2 k w resistor r12 1 200 w trimpot bourns 3386p1201 r13 1 1 k w trimpot bourns 3386p1102 s1 1 spdt miniature switch nkk ss12sdp2 tp1 1 yellow testpoint control design tp1040104 tp2 1 blue testpoint control design tp1040106 tp3 1 black testpoint control design tp1040100 tp4 1 green testpoint control design tp1040105 u1 1 quad op amp motorola mc33274 u2 1 8 v regulator motorola mc78l08acp u3 1 ad654 analog devices ad654 u4 1 5 v regulator motorola mc78l05acp u5 1 smallsignal fet motorola bs107a x1 1 pressure sensor motorola mpx2100dp note: all resistors are 1/4 watt, 5% tolerance values. all capacitors are 50 v rated, 20% tolerance values. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3268 motorola sensor device data www.motorola.com/semiconductors circuit operation the voltage signal conditioning portion of this circuit is a variation on the classic instrumentation amplifier configuration. it is capable of providing high differential gain and good commonmode rejection with very high input impedance; however, it provides a more user friendly method of performing the offset/bias point adjustment. it uses four op amps and several resistors to amplify and level shift the sensor's output. most of the amplification is done in u1a which is configured as a differential amplifier. unwanted current flow through the sensor is prevented by buffer u1b. at zero pressure the differential voltage from pin 2 to pin 4 on the sensor has been precision trimmed to essentially zero volts. the commonmode voltage on each of these nodes is 4 v (onehalf the sensor supply voltage). the zero pressure output voltage at pin 1 of u1a is then 4.0 v, since any other voltage would be coupled back to pin 2 via r5 and create a nonzero bias across u1a's differential inputs. this 4.0 v zero pressure dc output voltage is then level translated to the desired zero pressure offset voltage by u1c and u1d. the offset voltage is produced by r4 and adjustment trimpot r12. r7's value is such that the total source impedance into pin 13 is approximately 1 k. the gain is approximately (r5/r6)(1 + r11/r10), which is 125 for the values shown in figure 2. a gain of 125 is selected to provide a 4 v span for 32 mv of fullscale sensor output (at a sensor supply voltage of 8 v). the resulting .5 v to 4.5 v output from u1c is then converted by the v/f converter to the nominal 110 khz that has been specified. the ad654 v/f converter receives the amplified sensor output at pin 8 of op amp u1c. the fullscale frequency is determined by r3, r13 and c3 according to the following formula: f out (full-scale) v in ( 10v )( r3 r13 ) c3 for best performance, r3 and r13 should be chosen to provide 1 ma of drive current at the fullscale voltage produced at pin 3 of the ad654 (u3). the input stage of the ad654 is an opamp; thus, it will work to make the voltage at pin 3 of u3 equal to the voltage seen at pin 4 of u3 (pins 3 and 4 are the input terminals of the op amp). since the amplified sensor output will be 4.5 v at fullscale pressure, r3 + r13 should be approximately equal to 4.5 k w to have optimal linearity performance. once the total resistance from pin 3 of u3 to ground is set, the value of c3 will determine the fullscale frequency output of the v/f. trimpot r13 should be sized (relative to r3 value) to provide the desired amount of fullscale frequency adjustment. the zeropressure frequency is adjusted via the offset adjust provided for calibrating the offset voltage of the signal conditioned sensor output. for additional information on using this particular v/f converter, see the applications information provided in the analog devices data conversion products databook. the frequency output has its edge transitions aspedo up by a smallsignal fet inverter. this final output is directly compatible with microprocessor timer inputs, as well as any other highspeed cmos logic. the amplifier portion of this circuit has been patented by motorola inc. and was introduced on evaluation board devb150a. additional information pertaining to this circuit and the evaluation board devb150a is contained in motorola application note an1313. 1 test/calibration procedure 1. connect a +12 v supply between b+ and gnd terminals on the connector cn1. 2. connect a frequency counter or scope probe on the f out terminal of cn1 or on tp1 with the test instrumentation ground clipped to tp3 or gnd. 3 . turn the power switch, s1, to the on position. power led, d1, should be illuminated. verify that the voltage at tp2 and tp4 (relative to gnd or tp3) is 5 v and 8 v, respectively. while monitoring the frequency output by whichever means one has chosen, one should see a 50% duty cycle square wave signal. 4. turn the wiper of the offset adjust trimpot, r12, to the approximate center of the pot. 5. apply 100 kpa to pressure port p1 of the mpx2100dp (topside port on marked side of the package) sensor, x1. 6. adjust the fullscale trimpot, r13, until the output frequency is 10 khz. if 10 khz is not within the trim range of the fullscale adjustment trimpot, tweak the offset adjust trimpot to obtain 10 khz (remember, the offset pot was at an arbitrary midrange setting as per step 4). 7. apply zero pressure to the pressure port (i.e., both ports at ambient pressure, no differential pressure applied). adjust offset trimpot so frequency output is 1 khz. 8. verify that zero pressure and fullscale pressure (100 kpa) produce 1 and 10 khz respectively, at f out and/or tp1. a second iteration of adjustment on both fullscale and offset may be necessary to fine tune the 1 10 khz range. conclusion transforming conventional analog voltage sensor outputs to frequency has great utility for a variety of applications. sensing remotely and/or in noisy environments is particularly challenging for lowlevel (mv) voltage output sensors such as the mpx2000 series pressure sensors. converting the mpx2000 sensor output to frequency is relatively easy to accomplish, while providing the noise immunity required for accurate pressure sensing. the evaluation board presented is an excellent tool for either astandaloneo evaluation of the mpx2000 series pressure sensors or as a building block for system prototyping which can make use of devb160 as a adropino frequency output sensor solution. the output of the devb160 circuit is ideally conditioned for interfacing to mcu timer inputs that can measure the sensor frequency signal. references 1. schultz, warren (motorola, inc.), asensor building block evaluation board,o motorola application note an1313. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3269 motorola sensor device data www.motorola.com/semiconductors prepared by: warren schultz discrete applications engineering introduction the most popular silicon pressure sensors are piezoresistive bridges that produce a differential output voltage in response to pressure applied to a thin silicon diaphragm. output voltage for these sensors is generally 25 to 50 mv full scale. interface to microcomputers, therefore, generally involves gaining up the relatively small output voltage, performing a differential to single ended conversion, and scaling the analog signal into a range appropriate for analog to digital conversion. alternately, the analog pressure signal can be converted to a frequency modulated 5 v waveform or 420 ma current loop, either of which is relatively immune to noise on long interconnect lines. a variety of circuit techniques that address interface design are presented. sensing amplifiers, analog to digital conversion, frequency modulation and 420 ma current loops are considered. pressure sensor basics the essence of piezoresistive pressure sensors is the wheatstone bridge shown in figure 1. bridge resistors rp1, rp2, rv1 and rv2 are arranged on a thin silicon diaphragm such that when pressure is applied rp1 and rp2 increase in value while rv1 and rv2 decrease a similar amount. pressure on the diaphragm, therefore, unbalances the bridge and produces a differential output signal. one of the fundamental properties of this structure is that the differential output voltage is directly proportional to bias voltage b+. this characteristic implies that the accuracy of the pressure measurement depends directly on the tolerance of the bias supply. it also provides a convenient means for temperature compensation. the bridge resistors are silicon resistors that have positive temperature coefficients. therefore, when they are placed in series with zero t c temperature compensation resistors rc1 and rc2 the amount of voltage applied to the bridge increases with temperature. this increase in voltage produces an increase in electrical sensitivity which offsets and compensates for the negative temperature coefficient associated with piezoresistance. since rc1 and rc2 are approximately equal, the output voltage common mode is very nearly fixed at 1/2 b + . in a typical mpx2100 sensor, the bridge resistors are nominally 425 ohms; rc1 and rc2 are nominally 680 ohms. with these values and 10 v applied to b + , a delta r of 1.8 ohms at full scale pressure produces 40 mv of differential output voltage. figure 1. sensor equivalent circuit return b+ rc1 rv1 s+ rp1 rp2 rv2 s rc2 pressure instrumentation amplifier interfaces instrumentation amplifiers are by far the most common interface circuits that are used with pressure sensors. an example of an inexpensive instrumentation amplifier based interface circuit is shown in figure 2. it uses an mc33274 quad operational amplifier and several resistors that are configured as a classic instrumentation amplifier with one important exception. in an instrumentation amplifier resistor r3 is normally returned to ground. returning r3 to ground sets the output voltage for zero differential input to 0 v dc. for microcomputer interface a positive offset voltage on the order of 0.3 to 0.8 v is generally desired. therefore, r3 is connected to pin 14 of u1d which supplies a buffered offset voltage that is derived from the wiper of r6. this voltage establishes a dc output for zero differential input. the translation is one to one. within the tolerances of the circuit, whatever voltage appears at the wiper of r6 will also appear as the zero pressure dc offset voltage at the output. with r10 at 240 ohms, gain is set for a nominal value of 125. this provides a 4 v span for 32 mv of full scale sensor output. setting the offset voltage to .75 v results in a 0.75 v to 4.75 v output that is directly compatible with microprocessor a/d inputs. over a zero to 50 c temperature range, combined accuracy for an mpx2000 series sensor and this interface is on the order of 10%.

semiconductor application note rev 1 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3270 motorola sensor device data www.motorola.com/semiconductors figure 2. instrumentation amplifier interface b+ gnd c1 1 m f c2 0.1 m f c3 .001 m f u2 mc78l08acp u1b mc33274 i g o 3 r7 7.5 k r6 1 k 12 13 14 8 r2 1 k r5 r9 15 k 1 k u1a mc33274 r10 240* 5 6 4 7 r4 1 k r3 1 k u1c mc33274 10 9 2 3 1 2 3 4 1 xdcr1 mpx2000 series pressure sensor output 11 2 r8 15 k + + + + u1d mc33274 * note: for mpx2010, r10 = 150 ohms zero 1 for applications requiring greater precision a fully integrated instrument amplifier such as an ltc1100cn8 gives better results. in figure 3 one of these amplifiers is used to provide a gain of 100, as well as differential to single ended conversion. zero offset is provided by dividing down the precision reference to 0.5 v and buffering with u2b. this voltage is fed into the ltc1100cn8's ground pin which is equivalent to returning r3 to pin 14 of u1d in figure 2. an additional noninverting gain stage consisting of u2a, r1 and r2 is used to scale the sensor's full scale span to 4 v. r2 is also returned to the buffered .5 v to maintain the 0.5 v zero offset that was established in the instrumentation amplifier. output voltage range is therefore 0.5 to 4.5 v. both of these instrumentation amplifier circuits do their intended job with a relatively straightforward tradeoff between cost and performance. the circuit of figure 2 has the usual cumulative tolerance problem that is associated with instrumentation amplifiers that have discrete resistors, but it has a relatively low cost. the integrated instrumentation amplifier in figure 3 solves this problem with precision trimmed film resistors and also provides superior input offset performance. component cost, however, is significantly higher. sensor specific interface amplifier a low cost interface designed specifically for pressure sensors improves upon the instrumentation amplifier in figure 2. shown in figure 4, it uses one quad op amp and several resistors to amplify and level shift the sensor's output. most of the amplification is done in u1a which is configured as a differential amplifier. it is isolated from the sensor's positive output by u1b. the purpose of u1b is to prevent feedback current that flows through r5 and r6 from flowing into the sensor. at zero pressure the voltage from pin 2 to pin 4 on the sensor is 0 v. for example, let's say that the common mode voltage on these pins is 4.0 v. the zero pressure output voltage at pin 1 of u1a is then 4.0 v, since any other voltage would be coupled back to pin 2 via r6 and create a nonzero bias across u1a's differential inputs. this 4.0 v zero pressure dc output voltage is then level translated to the desired zero pressure offset voltage (v offset ) by u1c and u1d. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3271 motorola sensor device data www.motorola.com/semiconductors figure 3. precision instrument amplifier interface b + c1 1 m f 2 3 4 1 xdcr1 mpx2000 series pressure sensor output nc nc out trm nc v in vt gnd u1 1 2 3 4 8 7 6 5 mc1404 6 3 5 4 + 7 1 2 3 + 5 6 7 r4 1 k 1% mc34072 u2b r2 10 k 1% r1 6.04 k 1% 8 u2a c3 0.01 m f u1 mc34072 r3 19.1 k 1% c2 0.1 m f ltc1100cn8 + 1 4 figure 4. sensor specific interface circuit b+ gnd c1 1 m f c2 0.1 m f u2 mc78l08acp u1a mc33274 i g o 3 12 13 14 8 u1b mc33274 r5 120* 3 2 4 1 r4 1 k u1c mc33274 10 9 6 5 7 2 3 4 1 xdcr1 mpx2000 series pressure sensor output 11 2 r6 7.5 k + + + + * note: for mpx2010, r5 = 75 ohms u1d mc33274 r3 820 r1 2 k r2 2 k r9 200 zero cal. r8 1.5 k 1 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3272 motorola sensor device data www.motorola.com/semiconductors to see how the level translation works, let's look at the simplified schematic in figure 5. again assuming a common mode voltage of 4.0 v, the voltage applied to pin 12 of u1d is 4.0 v, implying that pin 13 is also at 4.0 v. this leaves 4.0 v v offset across r3, which is 3.5 v if v offset is set to 0.5 v. since no current flows into pin 13, the same current flows through both r3 and r4. with both of these resistors set to the same value, they have the same voltage drop, implying a 3.5 v drop across r4. adding the voltages (0.5 + 3.5 + 3.5) yields 7.5 v at pin 14 of u1d. similarly 4.0 v at pin 10 of u1c implies 4.0 v at pin 9, and the drop across r2 is 7.5 v 4.0 v = 3.5 v. again 3.5 v across r2 implies an equal drop across r1, and the voltage at pin 8 is 4.0 v 3.5 v = .5 v. for this dc output voltage to be independent of the sensor's common mode voltage it is necessary to satisfy the condition that r4/r3 = r2/r1. in figure 4, v offset is produced by r8 and adjustment pot r9. r3's value is adjusted such that the total source impedance into pin 13 is approximately 1 k. figure 5. simplified sensor specific interface b+ gnd u1a mc33274 12 13 14 8 u1b mc33274 r5 120* 3 2 4 1 r4 1 k u1c mc33274 10 9 6 5 7 2 3 4 1 xdcr1 mpx2000 series pressure sensor output 11 r6 7.5 k + + + + *note: for mpx2010, r5 = 75 ohms u1d mc33274 r3 1 k r1 2 k r2 2 k v +8 offset gain is approximately (r6/r5)(r1/r2 + 1), which is 125 for the values shown in figure 4. a gain of 125 is selected to provide a 4 v span for the 32 mv of full scale sensor output that is obtained with 8 v b + . the resulting 0.5 v to 4.5 v output from u1c is preferable to the 0.75 to 4.75 v range developed by the instrument amplifier configuration in figure 2. it also uses fewer parts. this circuit does not have the instrument amplifier's propensity for oscillation and therefore does not require compensation capacitor c3 that is shown in figure 2. it also requires one less resistor, which in addition to reducing component count also reduces accumulated tolerances due to resistor variations. this circuit as well as the instrumentation amplifier interfaces in figures 2 and 3 is designed for direct connection to a microcomputer a/d input. using the mc68hc11 as an example, the interface circuit output is connected to any of the e ports, such as port e0 as shown in figure 6. to get maximum accuracy from the a/d conversion, v refh is tied to 4.85 v and v refl is tied to 0.30 v by dividing down a 5 v reference with 1% resistors. single slope a/d converter the 8 bit a/d converters that are commonly available on chip in microcomputers are usually well suited to pressure sensing applications. in applications that require more than 8 bits, the circuit in figure 7 extends resolution to 11 bits with an external analogtodigital converter. it also provides an interface to digital systems that do not have an internal a/d function. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3273 motorola sensor device data www.motorola.com/semiconductors figure 6. application example return b+ rc1 rv1 s+ rp1 rp2 rv2 s rc2 bias + e b+ interface amplifier output gnd gnd vrefh vrefl +5 v 15.0 ohms 1% 30.1 ohms 1% 4.85 v .302 v 453 ohms 1% 0 1 2 3 4 5 6 7 port e mc68hc11 vss mpx2000 series pressure sensor vs beginning with the ramp generator, a timing ramp is generated with current source u5 and capacitor c3. initialization is provided by q1 which sets the voltage on c3 at approximately ground. with the values shown, 470 m a flowing into 0.47 m f provide approximately a 5 msec ramp time from zero to 5 v. assuming zero pressure on the sensor, inputs to both comparators u2a and u2b are at the same voltage. therefore, as the ramp voltage sweeps from zero to 5 v, both pa0 and pa1 will go low at the same time when the ramp voltage exceeds the common mode voltage. the processor counts the number of clock cycles between the time that pa0 and pa1 go low, reading zero for zero pressure. in this circuit, u4a and u4b form the front end of an instrument amplifier. they differentially amplify the sensor's output. the resulting amplified differential signal is then sampled and held in u1 and u3. the sample and hold function is performed in order to keep input data constant during the conversion process. the stabilized signals coming out of u1 and u3 feed a higher output voltage to u2a than u2b, assuming that pressure is applied to the sensor. therefore, the ramp will trip u2b before u2a is tripped, creating a time difference between pa0 going low and pa1 going low. the processor reads the number of clock cycles between these two events. this number is then linearly scaled with software to represent the amplified output voltage, accomplishing the analog to digital conversion. when the ramp reaches the reference voltage established by r9 and r10, comparator u2c is tripped, and a reset command is generated. to accomplish reset, q1 is turned on with an output from pa7, and the sample and hold circuits are delatched with an output from pb1. resolution is limited by clock frequency and ramp linearity. with the ramp generator shown in figure 7 and a clock frequency of 2 mhz; resolution is 11 bits. from a software point of view, the a/d conversion consists of latching the sample and hold, reading the value of the microcomputer's free running counter, turning off q1, and waiting for the three comparator outputs to change state from logic 1 to logic 0. the analog input voltage is determined by counting, in 0.5 m sec steps, the number of clock cycles between pa0 and pa1 going low. long distance interfaces in applications where there is a significant distance between the sensor and microcomputer, two types of interfaces are typically used. they are frequency output and 420 ma loops. in the frequency output topology, pressure is converted into a zero to 5 v digital signal whose frequency varies linearly with pressure. a minimum frequency corresponds to zero pressure and above this, frequency output is determined by a hz/unit pressure scaling factor. if minimizing the number of wires to a remote sensor is the most important design consideration, 420 ma current loops are the topology of choice. these loops utilize power and ground as the 420 ma signal line and therefore require only two wires to the sensor. in this topology 4 ma of total current drain from the sensor corresponds to zero pressure, and 20 ma to full scale. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3274 motorola sensor device data www.motorola.com/semiconductors +5 u4a mc33078 r2 402 k note: unless otherwise specified all resistors are 1% metal film 4 1 3 8 76 u4b mc33078 r3 402 k 3 8 76 14 u3 lf398a u1 + + + 5 5 r8 22 k 5% 10 11 6 7 5 4 lm139a lm139a lm139a u2b u2d u2a 1 2 13 +8.5 8.5 +8.5 8.5 lf398a r7 22 k 5% pa0 pb1 pa1 u5 lm334z-3 d1 1n914 r4 147 r6 1.5 k 5% r5 4.7 +10 q1 2n7000 8 9 14 u2c lm139a r10 9.09 k r9 1 k +5 + pa7 pa2 u7 mc68hc11e9fn c4 0.01 f m polyprop c5 0.01 f m polyprop c1 22 pf c2 22 pf c3 0.47 f m c7 0.1 f m xdcr1 mpx2000 series pressure sensor r5 120* 1 2 3 4 4 3 2 1 11 6 5 + + 7 5% figure 7. single slope a/d converter f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3275 motorola sensor device data www.motorola.com/semiconductors * note: for mpx2010, r8 = 75 ohms b+ gnd r6 2 k r7 2 k u2c mc33274 r1 1 k r2 820 xdcr1 mpx2000 series pressure sensor u2a mc33274 u2b mc33274 r4 7.5 k 12 13 14 u2d mc33274 10 9 8 1 3 2 i g o c1 1 f m r8 120* 3 4 67 c t c t + v s v rt v s c o m f r11 4.3 k 52 r12 1 k full scale cal. 1 r5 1.5 k 200 r3 u1 mc78l08acp c2 0.1 f m 1 3 i g o q1 bs107a 2 r9 1 k c3 0.01 f m 8 nominal output: 5 v 0 u3 ad654 zero cal. u4 mc78l05acp c4 0.1 f m output r10 240 out in 1 khz @ zero pressure 10 khz @ full scale 2 4 3 3 2 4 1 6 5 7 11 + + + + figure 8. frequency output pressure sensor f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3276 motorola sensor device data www.motorola.com/semiconductors a relatively straightforward circuit for converting pressure to frequency is shown in figure 8. it consists of three basic parts. the interface amplifier is the same circuit that was described in figure 4. its 0.5 to 4.5 v output is fed directly into an ad654 voltagetofrequency converter. on the ad654, c3 sets nominal output frequency. zero pressure output is calibrated to 1 khz by adjusting the zero pressure input voltage with r3. full scale adjustments are made with r12 which sets the full scale frequency to 10 khz. the output of the ad654 is then fed into a buffer consisting of q1 and r10. the buffer is used to clean up the edges and level translate the output to 5 v. advantages of this approach are that the frequency output is easily read by a microcomputer's timer and transmission over a twisted pair line is relatively easy. where very long distances are involved, the primary disadvantage is that 3 wires (v cc , ground and an output line) are routed to the sensor. a 420 ma loop reduces the number of wires to two. its output is embedded in the v cc and ground lines as an active current source. a straightforward way to apply this technique to pressure sensing is shown in figure 9. in this figure an mpx7000 series high impedance pressure sensor is mated to an xtr101 420 ma twowire transmitter. it is set up to pull 4 ma from its power line at zero pressure and 20 ma at full scale. at the receiving end a 240 ohm resistor referenced to signal ground will provide a 0.96 to 4.8 v signal that is suitable for microcomputer a/d inputs. figure 9. 420 ma pressure transducer 2 3 4 1 9 1 3 7 1 4 2 1 .96 4.8 v 24 v p loop 240 return d1 1n4002 420 ma output r1 750 1/2 w q1 mpsa06 u1 xtr101 xdcr1 mpx7000 series sensor d2 1n4565a 6.4 v @ .5 ma r3 30 r5 100 span r6 100 k offset r4 1m 12 1 1 1 0 8 4 5 6 3 c1 0.01 m f + 2 ma + r2 1 k bias for the sensor is provided by two 1 ma current sources (pins 10 and 11) that are tied in parallel and run into a 1n4565a 6.4 v temperature compensated zener reference. the sensor's differential output is fed directly into xtr101's inverting and noninverting inputs. zero pressure offset is calibrated to 4 ma with r6. biased with 6.4 v, the sensor's full scale output is 24.8 mv. given this input r3 + r5 nominally total 64 ohms to produce the 16 ma span required for 20 ma full scale. calibration is set with r5. the xtr101 requires that the differential input voltage at pins 3 and 4 has a common mode voltage between 4 and 6 v. the sensor's common mode voltage is one half its supply voltage or 3.2 v. r2 boosts this common mode voltage by 1k 2 ma or 2 v, establishing a common mode voltage for the transmitter's input of 5.2 v. to allow operation over a 12 to 40 v range, dissipation is offloaded from the ic by boosting the output with q1 and r1. d1 is also included for protection. it prohibits reverse polarity from causing damage. advantages of this topology include simplicity and, of course, the two wire interface. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3277 motorola sensor device data www.motorola.com/semiconductors 1 2 3 4 5 6 7 28 33 34 35 36 37 38 39 8 31 32 9 10 11 29 30 12 26 27 13 14 15 24 25 16 22 23 17 18 19 20 21 40 pc0 pc2 pc1 pc7 pc6 pc5 pc4 pc3 pb2 pb1 pb7 pb6 pb5 pb4 pb3 pa0 pa2 pa1 pa7 pa6 pa5 pa4 pa3 1 2 3 xdcr1 mpx5100 r4 4.7 k r3 10 k r2 10 k u2 mc34064p-5 j1 j2 c1 22 pf r1 10 m y1 4 mhz c2 22 pf r6 15 % r5 453 % r7 30.1 % vrh vrl d/a tcap1 tcap2 vdd pd0 pd1 pd2 pd3 vpp6 irq pd5 reset pd6 pd7 osc1 osc2 v rdi tdo pd4 u1 mc68hc705b5fn ieee lcd 5657 or equivalent liquid crystal display +5 ss figure 10. mpx5100 lcd pressure gauge f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3278 motorola sensor device data www.motorola.com/semiconductors direct interface with integrated sensors the simplest interface is achieved with an integrated sensor and a microcomputer that has an onchip a/d converter. figure 10 shows an lcd pressure gauge that is made with an mpx5100 integrated sensor and mc68hc05 microcomputer. although the total schematic is reasonably complicated, the interface between the sensor and the micro is a single wire. the mpx5100 has an internal amplifier that outputs a 0.5 to 4.5 v signal that inputs directly to a/d port pd5 on the hc05. the software in this system is written such that the processor assumes zero pressure at power up, reads the sensor's output voltage, and stores this value as zero pressure offset. full scale span is adjustable with jumpers j1 and j2. for this particular system the software is written such that with j1 out and j2 in, span is decreased by 1.5%. similarly with j1 in and j2 out, span is increased by 1.5%. given the 2.5% full scale spec on the sensor, these jumpers allow calibration to 1% without the use of pots. mix and match the circuits that have been described so far are intended to be used as functional blocks. they may be combined in a variety of ways to meet the particular needs of an application. for example, the frequency output pressure sensor in figure 8 uses the sensor interface circuit described in figure 4 to provide an input to the voltagetofrequency converter. alternately, an mpx5100 could be directly connected to pin 4 of the ad654 or the output of figure 3's precision instrumentation amplifier interface could by substituted in the same way. similarly, the pressure gauge described in figure 10 could be constructed with any of the interfaces that have been described. conclusion the circuits that have been shown here are intended to make interfacing semiconductor pressure sensors to digital systems easier. they provide cost effective and relatively simple ways of interfacing sensors to microcomputers. the seven different circuits contain many tradeoffs that can be matched to the needs of individual applications. when considering these tradeoffs it is important to throw software into the equation. techniques such as automatic zero pressure calibration can allow one of the inexpensive analog interfaces to provide performance that could otherwise only be obtained with a more costly precision interface. references 1. baum, jeff, afrequency output conversion for mpx2000 series pressure sensors,o motorola applica- tion note an1316/d. 2. lucas, william, aan evaluation system for direct inter- face of the mpx5100 pressure sensor with a micropro- cessor,o motorola application note an1305. 3. lucas, william, aan evaluation system for interfacing the mpx2000 series pressure sensors to a microproces- sor,o motorola application note an1315. 4. schultz, warren, acompensated sensor bar graph pressure gauge,o motorola application note an1309. 5. schultz, warren, ainterfaced sensor evaluation board,o motorola application note an1312. 6. schultz, warren, asensor building block evaluation board,o motorola application note an1313. 7. williams, denise, aa simple 420 ma pressure trans- ducer evaluation board,o motorola application note an1303. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3279 motorola sensor device data www.motorola.com/semiconductors
prepared by: warren schultz discrete applications engineering introduction bar graph displays are noted for their ability to very quickly convey a relative sense of how much of something is present. they are particularly useful in process monitoring applications where quick communication of a relative value is more important than providing specific data. designing bar graph pressure gauges based upon semiconductor pressure sensors is relatively straightforward. the sensors can be interfaced to bar graph display drive ic's, microcomputers and mc33161 voltage monitors. design examples for all three types are included. bar graph display driver interfacing semiconductor pressure sensors to a bar graph display ic such as an lm3914 is very similar to microcomputer interface. the same 0.5 to 4.5 v analog signal that a microcomputer's a/d converter wants to see is also quite suitable for driving an lm3914. in figure 1, this interface is provided by dual op amp u2 and several resistors. the op amp interface amplifies and level shifts the sensor's output. to see how this amplifier works, simplify it by grounding the output of voltage divider r3, r5. if the common mode voltage at pins 2 and 4 of the sensor is 4.0 v, then pin 2 of u2a and pin 6 of u2b are also at 4.0 v. this puts 4.0 v across r6. assuming that the current in r4 is equal to the current in r6, 323 m a ? 100 ohms produces a 32 mv drop across r4 which adds to the 4.0 v at pin 2. the output voltage at pin 1 of u2a is, therefore, 4.032 v. this puts 4.032 4.0 v across r2, producing 43 m a. the same current flowing through r1 again produces a voltage drop of 4.0 v, which sets the output at zero. substituting a divider output greater than zero into this calculation reveals that the zero pressure output voltage is equal to the output voltage of divider r3, r5. for this dc output voltage to be independent of the sensor's common mode voltage, it is necessary to satisfy the condition that r1/r2 = r6/r4. gain can be determined by assuming a differential output at the sensor and going through the same calculation. to do this assume 100 mv of differential output, which puts pin 2 of u2a at 3.95 v, and pin 6 of u2b at 4.05 v. therefore, 3.95 v is applied to r6, generating 319 m a. this current flowing through r4 produces 31.9 mv, placing pin 1 of u2a at 3950 mv + 31.9 mv = 3982 mv. the voltage across r2 is then 4050 mv 3982 mv = 68 mv, which produces a current of 91 m a that flows into r1. the output voltage is then 4.05 v + (91 m a ? 93.1k) = 12.5 v. dividing 12.5 v by the 100 mv input yields a gain of 125, which provides a 4.0 v span for 32 mv of full scale sensor output. setting divider r3, r5 at 0.5 v results in a 0.5 v to 4.5 v output that is easily tied to an lm3914. the block diagram that appears in figure 2 shows the lm3914's internal architecture. since the lower resistor in the input comparator chain is pinned out at r lo , it is a simple matter to tie this pin to a voltage that is approximately equal to the interface circuit's 0.5 v zero pressure output voltage. returning to figure 1, this is accomplished by using the zero pressure offset voltage that is generated at the output of divider r3, r5. again looking at figure 1, full scale is set by adjusting the upper comparator's reference voltage to match the sensor's output at full pressure. an internal regulator on the lm3914 sets this voltage with the aid of resistors r7, r9, and adjustment pot r8. eight volt regulated power is supplied by an mc78l08. the led's are powered directly from lm3914 outputs, which are set up as current sources. output current to each led is approximately 10 times the reference current that flows from pin 7 through r7, r8, and r9 to ground. in this design it is nominally (4.5 v/4.9 k)10 = 9.2 ma. over a zero to 50 c temperature range combined accuracy for the sensor, interface, and driver ic are 10%. given a 10 segment display total accuracy for the bar graph readout is approximately (10 kpa +10%). this circuit can be simplified by substituting an mpx5100 integrated sensor for the mpx2100 and the op amp interface. the resulting schematic is shown in figure 3. in this case zero reference for the bar graph is provided by dividing down the 5 v regulator with r4, r1 and adjustment pot r6. the voltage at the wiper of r6 is adjusted to match the sensor's zero pressure offset voltage. it is connected to r lo to zero the bar graph. semiconductor application note rev 1 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3280 motorola sensor device data www.motorola.com/semiconductors 2 3 4 1 9 8 7 6 5 4 3 2 1 10 11 12 13 14 15 16 17 18 d1 d2 d3 d4 d5 d6 d7 d8 d9 d10 b+ gnd i g o mc78l08acp u1 c2 0.1 m f 1 u2a mc33272 5 6 4 + + xdcr1 mpx2000 series sensor r9 2.7 k r8 1 k r7 1.2 k u3 lm3914n d1-d10 mv57164 bar graph 3 2 led gnd b+ rlo sig rhi ref adj mod led led led led led led led led led c2 1 m f u2b mc3327 2 7 for mpx2010 sensors: r1 = 150 k r4 = 61.9 ohms 8 r1 93.1 k 1% c3 0.001 m f 3 2 r6 12.4 k 1% r5 100 1% r3 1.5 k 1% r2 750 1% r4 100 1% reference voltage source 1.25 v mode select amplifier + buffer ref out this load determines led brightness controls type of display, bar or single led comparator 1 of 10 lm391 4 10 11 12 13 14 15 16 17 18 1 1 k 1 k 1 k 1 k 1 k 1 k 1 k 1 k 1 k 1 k led v + r hi 6 7 8 3 4 5 r lo ref adj v + sig in v 9 2 from pin 11 v + 20 k + + + + + + + + + + + figure 1. compensated sensor bar graph pressure gauge figure 2. lm3914 block diagram f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3281 motorola sensor device data www.motorola.com/semiconductors 1 3 2 9 8 7 6 5 4 3 2 1 10 11 12 13 14 15 16 17 18 d1 d2 d3 d4 d5 d6 d7 d8 d9 d10 +12 v gnd i g mc78l05acp u3 u2 mpx5100 r3 2.7 k r5 1 k r2 1.2 k u1 lm3914 3 2 led gnd b+ r lo sig rhi ref adj mod led led led led led led led led led c2 1 m f 1 o full scale cal. zero cal. c1 0.1 m f r4 1.3 k r1 100 r6 100 1 3 2 d1 d2 d3 d4 d5 +5 d/a tcap1 tcap2 v dd pd0 pd1 pd2 pd3 vpp6 irq pd5 vrh vrl pc0 pc1 pc2 pc3 pc4 xdcr1 mpx5100 u2 r3 4.7 k r2 10 k r1 10 k mc34064p-5 j1 j2 c1 22 pf r4 10 m y1 4 mhz osc1 pd7 pd6 reset c2 22 pf v ss rdi tdo osc2 i2 mdc4510a i3 mdc4510a i4 mdc4510a i5 mdc4510a mv53214a mv54124a mv54124a mv54124a mv57124a u1 mc68hc705b5fn i1 mdc4510a pd4 figure 3. mpx5100 bar graph pressure gauge figure 4. microcomputer bar graph pressure gauge f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3282 motorola sensor device data www.motorola.com/semiconductors d6 mv53124a low b+ c2 0.1 m f 3 u1 mc78l08acp i o g 2 1 32 1 4 5 6 7 u2b mc33272 c1 0.1 m f u2a mc33272 1 3 2 4 r8 10 k low r9 10 k hi r10 2.7 k r11 2.7 k i2 mdc4010a i3 mdc4010a d4 mv54124a 0 k d5 mv57124a high i1 mdc4510a 1 3 2 d1 1n914 d2 1n914 8 7 6 5 1 2 3 4 u3 mc33161 ref in1 in2 gnd v cc mode out1 out2 r7 7.5 k + + 1 2 1 2 gnd xdcr1 mpx2000 series sensor r3 6.65 k 1% r5 1.33 k 1% r6 11.3 k 1% r4 100 1% r2 750 1% c3 0.001 m f r1 93.1 k 1% 8 + + + + v ref v cc 2.54 v reference out1 out2 8 6 5 3 2 7 1 mode select input1 input2 1.27 v 1.27 v gnd 4 0.6 v 2.8 v figure 5. an inexpensive 3segment processor monitor figure 6. mc33161 block diagram f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3283 motorola sensor device data www.motorola.com/semiconductors microcomputer bar graph microcomputers with internal a/d converters such as an mc68hc05b5 lend themselves to easily creating bar graphs. using the a/d converter to measure the sensor's analog output voltage and output ports to individually switch led's makes a relatively straightforward pressure gauge. this type of design is facilitated by a new mdc4510a gated current sink. the mdc4510a takes one of the processor's logic outputs and switches 10 ma to an led. one advantage of this approach is that it is very flexible regarding the number of segments that are used, and has the availability through software to independently adjust scaling factors for each segment. this approach is particularly useful for process monitoring in systems where a microprocessor is already in place. figure 4 shows a direct connection from an mpx5100 sensor to the microcomputer. similar to the previous example, an mpx2000 series sensor with the op amp interface that is shown in figure 1 can be substituted for the mpx5100. in this case the op amp interface's output at pin 7 ties to port pd5, and its supply needs to come from a source greater than 6.5 v. process monitor for applications where an inexpensive high-low-ok process monitor is required, the circuit in figure 5 does a good job. it uses an mc33161 universal voltage monitor and the same analog interface previously described to indicate high, low or in-range pressure. a block diagram of the mc33161 is illustrated in figure 6. by tying pin 1 to pin 7 it is set up as a window detector. whenever input 1 exceeds 1.27 v, two logic ones are placed at the inputs of its exclusive or gate, turning off output 1. therefore this output is on unless the lower threshold is exceeded. when 1.27 v is exceeded on input 2, just the opposite occurs. a single logic one appears at its exclusive or gate, turning on output 2. these two outputs drive led's through mdc4010a 10 ma current sources to indicate low pressure and high pressure. returning to figure 5, an in-range indication is developed by turning on current source i1 whenever both the high and low outputs are off. this function is accomplished with a discrete gate made from d1, d2 and r7. its output feeds the input of switched current source i1, turning it on with r7 when neither d1 nor d2 is forward biased. thresholds are set independently with r8 and r9. they sample the same 4.0 v full scale span that is used in the other examples. however, zero pressure offset is targeted for 1.3 v. this voltage was chosen to approximate the 1.27 v reference at both inputs, which avoids throwing away the sensor's analog output signal to overcome the mc33161's input threshold. in addition, r10 and r11 are selected such that at full scale output, ie., 5.3 v on pin 7, the low side of the pots is nominally at 1.1 v. this keeps the minimum input just below the comparator thresholds of 1.27 v, and maximizes the resolution available from adjustment pots r8 and r9. when level adjustment is not desired, r8 r11 can be replaced by a simpler string of three fixed resistors. conclusion the circuits that have been shown here are intended to make simple, practical and cost effective bar graph pressure gauges. their application involves a variety of trade-offs that can be matched to the needs of individual applications. in general, the most important trade-offs are the number of segments required and processor utilization. if the system in which the bar graph is used already has a microprocessor with unused a/d channels and i/o ports, tying mdc4510a current sources to the unused output ports is a very cost effective solution. on a stand-alone basis, the mc33161 based process monitor is the most cost effective where only 2 or 3 segments are required. applications that require a larger number of segments are generally best served by one of the circuits that uses a dedicated bar graph display. references 1. alberkrack, jade, & barrow, stephen; apower supply monitor ic fills voltage sensing roles,o power conver- sion & intelligent motion, october 1991. 2. lucas, william, aan evaluation system for direct inter- face of the mpx5100 pressure sensor with a micropro- cessor,o motorola application note an1305. 3. schultz, warren, aintegrated sensor simplifies bar graph pressure gauge,o motorola application note an1304. 4. schultz, warren, acompensated sensor bar graph pressure gauge,o motorola application note an1309. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3284 motorola sensor device data www.motorola.com/semiconductors prepared by: warren schultz discrete applications engineering introduction amplifiers for interfacing semiconductor pressure sensors to electronic systems have historically been based upon classic instrumentation amplifier designs. instrumentation amplifiers have been widely used because they are well understood standard building blocks that also work reasonably well. for the specific job of interfacing semiconductor pressure sensors to today's mostly digital systems, other circuits can do a better job. this application note presents an evolution of amplifier design that begins with a classic instrumentation amplifier and ends with a simpler circuit that is better suited to sensor interface. interface amplifier requirements design requirements for interface amplifiers are determined by the sensor's output characteristics, and the zero to 5 v input range that is acceptable to microcomputer a/d converters. since the sensor's full scale output is typically tens of millivolts, the most obvious requirement is gain. gains from 100 to 250 are generally needed, depending upon bias voltage applied to the sensor and maximum pressure to be measured. a differential to singleended conversion is also required in order to translate the sensor's differential output into a single ended analog signal. in addition, level shifting is necessary to convert the sensor's 1/2 b + common mode voltage to an appropriate dc level. for microcomputer a/d inputs, generally that level is from 0.3 1.0 v. typical design targets are 0.5 v at zero pressure and enough gain to produce 4.5 v at full scale. the 0.5 v zero pressure offset allows for output saturation voltage in op amps operated with a single supply (v ee = 0). at the other end, 4.5 v full scale keeps the output within an a/d converter's 5 v range with a comfortable margin for component tolerances. the resulting 0.5 to 4.5 v singleended analog signal is also quite suitable for a variety of other applications such as bar graph pressure gauges and process monitors. classic instrumentation amplifier a classic instrumentation amplifier is shown in figure 1. this circuit provides the gain, level shifting and differential to singleended conversion that are required for sensor interface. it does not, however, provide for single supply operation with a zero pressure offset voltage in the desired range. + + + 8 10 9 r2 1 k 3 2 11 1 5 6 4 7 * note: for mpx2020 r10 = 150 ohms r 3 1 k r5 1 k r9 15 k r8 15 k + u1a mc33274 u1b mc33274 v ee r10 240* v cc output r4 1k u1c mc33274 c3 0.001 m f figure 1. classic instrumentation amplifier

semiconductor application note rev 2 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3285 motorola sensor device data www.motorola.com/semiconductors figure 2. instrumentation amplifier interface + + xdcr1 mpx2000 series pressure sensor + + b+ gnd output i o g c1 1 m f u2 mc78l08acp 3 1 2 1 2 4 3 1 2 3 11 r9 r5 r2 1 k 15 k 1 k 8 9 10 u1c mc33274 r3 1 k r4 1 k u1b mc33274 r8 15 k c3 0.001 m f 7 4 5 6 c2 0.1 m f r7 7.5 k zero r6 1 k 12 13 14 u1d mc33274 * note: for mpx2010 r10 = 150 ohms u1a mc33274 r10 240* to provide the desired dc offset, a slight modification is made in figure 2. r3 is connected to pin 14 of u1d, which supplies a buffered offset voltage that is derived from the wiper of r6. this voltage establishes a dc output for zero differential input. the translation is one to one. whatever voltage appears at the wiper of r6 will, within component tolerances, appear as the zero pressure dc offset voltage at the output. with r10 at 240 w gain is set for a nominal value of 125, providing a 4 v span for 32 mv of full scale sensor output. setting the offset voltage to 0.75 v, results in a 0.75 v to 4.75 v output that is directly compatible with microprocessor a/d inputs. this circuit works reasonably well, but has several notable limitations when made with discrete components. first, it has a relatively large number of resistors that have to be well matched. failure to match these resistors degrades common mode rejection and initial tolerance on zero pressure offset voltage. it also has two amplifiers in one gain loop, which makes stability more of an issue than it is in the following two alternatives. this circuit also has more of a limitation on zero pressure offset voltage than the other two. the minimum output voltage of u1d restricts the minimum zero pressure offset voltage that can be accommodated, given component tolerances. the result is a 0.75 v zero pressure offset voltage, compared to 0.5 v for each of the following two circuits. sensor specific amplifier the limitations associated with classic instrumentation amplifiers suggest that alternate approaches to sensor interface design are worth looking at. one such approach is shown in figure 3. it uses one quad op amp and several resistors to amplify and level shift the sensor's output. most of the amplification is done in u1a, which is configured as a differential amplifier. it is isolated from the sensor's minus output by u1b. the purpose of u1b is to prevent feedback current that flows through r5 and r6 from flowing into the sensor. at zero pressure the voltage from pin 2 to pin 4 on the sensor is zero v. for example, assume that the common mode voltage is 4.0 v. the zero pressure output voltage at pin 1 of u1a is then 4.0 v, since any other voltage would be coupled back to pin 2 via r6 and create a non zero bias across u1a's differential inputs. this 4.0 v zero pressure dc output voltage is then level translated to the desired zero pressure offset voltage by u1c and u1d. to see how the level translation works, assume that the wiper of r9 is at ground. with 4.0 v at pin 12, pin 13 is also at 4.0 v. this leaves 4.0 v across (r3+r9), which total essentially 1 k w . since no current flows into pin 13, the same current flows through r4, producing approximately 4.0 v across r4, as well. adding the voltages (4.0 + 4.0) yields 8.0 v at pin 14. similarly 4.0 v at pin 10 implies 4.0 v at pin 9, and the drop across r2 is 8.0 v 4.0 = 4.0 v. again 4.0 v across r2 implies an equal drop f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3286 motorola sensor device data www.motorola.com/semiconductors figure 3. sensor specific amplifier * note: for mpx2010 r5 = 75 ohms c1 1 m f i o g 3 1 2 b+ gnd out r9 200 zero cal. r8 1.5 k xdcr1 mpx2000 series pressure sensor 1 2 4 3 + u1a mc33274 1 4 3 2 tp2 +8 v c2 0.1 m f r6 7.5 k r5 120* + u1b mc33274 7 11 6 5 r3 820 + u1c mc33274 8 10 9 r1 2 k r2 2 k + u1d mc33274 14 12 13 r4 1 k u2 mc78l08acp across r1, and the voltage at pin 8 is 4.0 v 4.0 v = 0 v. in practice, the output of u1c will not go all the way to ground, and the voltage injected by r8 at the wiper of r9 is approximately translated into a dc offset. gain is approximately equal to r6/r5(r1/r2+1), which predicts 125 for the values shown in figure 3. a more exact calculation can be performed by doing a nodal analysis, which yields 127. cascading the gains of u1a and u1c using standard op amp gain equations does not give an exact result, because the sensor's negative going differential signal at pin 4 subtracts from the dc level that is amplified by u1c. setting offset to 0.5 v results in an analog zero to full scale range of 0.5 to 4.5 v. for this dc output voltage to be independent of the sensor's common mode voltage it is necessary to satisfy the condition that r1/r2 = (r3+r9)/r4. this approach to interface amplifier design is an improvement over the classic instrument amplifier in that it uses fewer resistors, is inherently more stable, and provides a zero pressure output voltage that can be targeted at .5 v. it has the same tolerance problem from matching discrete resistors that is associated with classic instrument amplifiers. sensor mini amp further improvements can be made with the circuit that is shown in figure 4. it uses one dual op amp and several resistors to amplify and level shift the sensor's output. to see how this amplifier works, let's simplify it by grounding the output of voltage divider r3, r5 and assuming that the divider impedance is added to r6, such that r6 = 12.4 k. if the common mode voltage at pins 2 and 4 of the sensor is 4.0 v, then pin 2 of u2a and pin 6 of u2b are also at 4.0 v. this puts 4.0 v across r6, producing 323 m a. assuming that the current in r4 is equal to the current in r6, 323 m a ? 100 w produces a 32 mv drop across r4 which adds to the 4.0 v at pin 2. the output voltage at pin 1 of u2a is, therefore, 4.032 v. this puts 4.032 4.0 v across r2, producing 43 m a. the same current flowing through r1 again produces a voltage drop of 4.0 v, which sets the output at zero. substituting a divider output greater than zero into this calculation reveals that the zero pressure output voltage is equal to the output voltage of divider r3, r5. for this dc output voltage to be independent of the sensor's common mode voltage it is necessary to satisfy the condition that r1/r2 = r6/r4, where r6 includes the divider impedance. gain can be determined by assuming a differential output at the sensor and going through the same calculation. to do this assume 100 mv of differential output, which puts pin 2 of u2a at 3.95 v, and pin 6 of u2b at 4.05 v. therefore, 3.95 v is applied to r6, generating 319 ua. this current flowing through r4 produces 31.9 mv, placing pin 1 of u2a at 3950 mv + 31.9 mv = 3982 mv. the voltage across r2 is then 4050 mv 3982 mv = 68 mv, which produces a current of 91 m a that flows into r1. the output voltage is then 4.05 v + (91 m a ? 93.1 k) = 12.5 v. dividing 12.5 v by the 100 mv input yields a gain of 125, which provides a 4 v span for 32 mv of full scale sensor output. setting divider r3, r5 at 0.5 v results in a 0.5 v to 4.5 v output that is comparable to the other two circuits. this circuit performs the same function as the other two with significantly fewer components and lower cost. in most cases it is the optimum choice for a low cost interface amplifier. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3287 motorola sensor device data www.motorola.com/semiconductors notes: r7 is nominally 39.2 k and selected for zero pressure v out = 0.5 v for mpx2010 sensors r1 = 150 k and r4 = 61.9 ohms c1 0.2 m f i o g 3 1 2 b+ gnd out c2 0.2 m f xdcr1 mpx2000 series sensor 1 2 4 3 u1b mc33272 1 4 3 2 + 8 6 r1 93.1 k 1% u1 mc78l08acp c2 0.001 m f r2 750 1% r4 100 1% r6 11 k 1% r5 1.33 k 1% r7 trim r3 39.2 k 1% 5 7 u2b mc33272 figure 4. sensor mini amp + performance performance differences between the three topologies are minor. accuracy is much more dependent upon the quality of the resistors and amplifiers that are used and less dependent on which of the three circuits are chosen. for example, input offset voltage error is essentially the same for all three circuits. to a first order approximation, it is equal to total gain times the difference in offset between the two amplifiers that are directly tied to the sensor. errors due to resistor tolerances are somewhat dependent upon circuit topology. however, they are much more dependent upon the choice of resistors. choosing 1% resistors rather than 5% resistors has a much larger impact on performance than the minor differences that result from circuit topology. assuming a zero pressure offset adjustment, any of these circuits with an mpx2000 series sensor, 1% resistors and an mc33274 amplifier results in a 5% pressure to voltage translation from 0 to 50 c. software calibration can significantly improve these numbers and eliminate the need for analog trim. conclusion although the classic instrumentation amplifier is the best known and most frequently used sensor interface amplifier, it is generally not the optimal choice for inexpensive circuits made from discrete components. the circuit that is shown in figure 4 performs the same interface function with significantly fewer components, less board space and at a lower cost. it is generally the preferred interface topology for mpx2000 series semiconductor pressure sensors. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3288 motorola sensor device data www.motorola.com/semiconductors
prepared by: chris winkler and jeff baum discrete applications engineering abstract the most recent advances in silicon micromachining technology have given rise to a variety of lowcost pressure sensor applications and solutions. certain applications had previously been hindered by the highcost, large size, and overall reliability limitations of electromechanical pressure sensing devices. furthermore, the integration of onchip temperature compensation and calibration has allowed a significant improvement in the accuracy and temperature stability of the sensor output signal. this technology allows for the development of both analog and microcomputerbased systems that can accurately resolve the small pressure changes encountered in many applications. one particular application of interest is the combination of a silicon pressure sensor and a microcontroller interface in the design of a digital barometer. the focus of the following documentation is to present a lowcost, simple approach to designing a digital barometer system. figure 1. barometer system digit1 digit2 digit3 digit4 mcu signal conditioning pressure sensor semiconductor application note rev 1 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3289 motorola sensor device data www.motorola.com/semiconductors introduction figure 1 shows the overall system architecture chosen for this application. this system serves as a building block, from which more advanced systems can be developed. enhanced accuracy, resolution, and additional features can be integrated in a more complex design. there are some preliminary concerns regarding the measurement of barometric pressure which directly affect the design considerations for this system. barometric pressure refers to the air pressure existing at any point within the earth's atmosphere. this pressure can be measured as an absolute pressure, (with reference to absolute vacuum) or can be referenced to some other value or scale. the meteorology and avionics industries traditionally measure the absolute pressure, and then reference it to a sea level pressure value. this complicated process is used in generating maps of weather systems. the atmospheric pressure at any altitude varies due to changing weather conditions over time. therefore, it can be difficult to determine the significance of a particular pressure measurement without additional information. however, once the pressure at a particular location and elevation is determined, the pressure can be calculated at any other altitude. mathematically, atmospheric pressure is exponentially related to altitude. this particular system is designed to track variations in barometric pressure once it is calibrated to a known pressure reference at a given altitude. for simplification, the standard atmospheric pressure at sea level is assumed to be 29.9 inhg. astandardo barometric pressure is measured at particular altitude at the average weather conditions for that altitude over time. the system described in this text is specified to accurately measure barometric pressure variations up to altitudes of 15,000 ft. this altitude corresponds to a standard pressure of approximately 15.0 inhg. as a result of changing weather conditions, the standard pressure at a given altitude can fluctuate approximately 1 inhg. in either direction. table 1 indicates standard barometric pressures at several altitudes of interest. mc68hc11e9 micro controller 4digit lcd & mc145453 display driver signal cond. amplifier mpx2100ap pressure sensor data clock synch figure 2. barometer system block diagram table 1. altitude versus pressure data altitude (ft.) pressure (inhg) 0 29.92 500 29.38 1,000 28.85 6,000 23.97 10,000 20.57 15,000 16.86 system overview in order to measure and display the correct barometric pressure, this system must perform several tasks. the measurement strategy is outlined below in figure 2. first, pressure is applied to the sensor. this produces a proportional differential output voltage in the millivolt range. this signal must then be amplified and levelshifted to a singleended, microcontroller (mcu) compatible level (0.5 4.5 v) by a signal conditioning circuit. the mcu will then sample the voltage at the analogtodigital converter (a/d) channel input, convert the digital measurement value to inches of mercury, and then display the correct pressure via the lcd interface. this process is repeated continuously. there are several significant performance features implemented into this system design. first, the system will digitally display barometric pressure in inches of mercury, with a resolution of approximately onetenth of an inch of mercury. in order to allow for operation over a wide altitude range (0 15,000 ft.), the system is designed to display barometric pressures ranging from 30.5 inhg. to a minimum of 15.0 inhg. the display will read aloo if the pressure measured is below 30.5 inhg. these pressures allow for the system to operate with the desired resolution in the range from sealevel to approximately 15,000 ft. an overview of these features is shown in table 2. table 2. system features overview display units inhg resolution 0.1 inhg. system range 15.0 30.5 inhg. altitude range 0 15,000 ft. design overview the following sections are included to detail the system design. the overall system will be described by considering the subsystems depicted in the system block diagram, figure 2. the design of each subsystem and its function in the overall system will be presented. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3290 motorola sensor device data www.motorola.com/semiconductors table 3. mpx2100ap electrical characteristics characteristic symbol minimum typical max unit pressure range p op 0 100 kpa supply voltage v s 10 16 vdc full scale span v fss 38.5 40 41.5 mv zero pressure offset v off 1.0 mv sensitivity s 0.4 mv/kpa linearity 0.05 %fss temperature effect on span 0.5 %fss temperature effect on offset 0.2 %fss pressure sensor the first and most important subsystem is the pressure transducer. this device converts the applied pressure into a proportional, differential voltage signal. this output signal will vary linearly with pressure. since the applied pressure in this application will approach a maximum level of 30.5 inhg. (100 kpa) at sea level, the sensor output must have a linear output response over this pressure range. also, the applied pressure must be measured with respect to a known reference pressure, preferably absolute zero pressure (vacuum). the device should also produce a stable output over the entire operating temperature range. the desired sensor for this application is a temperature compensated and calibrated, semiconductor pressure transducer, such as the motorola mpxm2102a series sensor family. the mpx2000 series sensors are available in fullscale pressure ranges from 10 kpa (1.5 psi) to 200 kpa (30 psi). furthermore, they are available in a variety of pressure configurations (gauge, differential, and absolute) and porting options. because of the pressure ranges involved with barometric pressure measurement, this system will employ an mpxm2102as (absolute with single port). this device will produce a linear voltage output in the pressure range of 0 to 100 kpa. the ambient pressure applied to the single port will be measured with respect to an evacuated cavity (vacuum reference). the electrical characteristics for this device are summarized in table 3. as indicated in table 3, the sensor can be operated at different supply voltages. the fullscale output of the sensor, which is specified at 40 mv nominally for a supply voltage of 10 vdc, changes linearly with supply voltage. all nondigital circuitry is operated at a regulated supply voltage of 8 vdc. therefore, the fullscale sensor output (also the output of the sensor at sea level) will be approximately 32 mv. 8 10 40 mv the sensor output voltage at the systems minimum range (15 inhg.) is approximately 16.2 mv. thus, the sensor output over the intended range of operations is expected to vary from 32 to 16.2 mv. these values can vary slightly for each sensor as the offset voltage and fullscale span tolerances indicate. signal conditioning circuitry in order to convert the smallsignal differential output signal of the sensor to mcu compatible levels, the next subsystem includes signal conditioning circuitry. the operational amplifier circuit is designed to amplify, levelshift, and ground reference the output signal. the signal is converted to a singleended, 0.5 4.5 vdc range. the schematic for this amplifier is shown in figure 3. this particular circuit is based on classic instrumentation amplifier design criteria. the differential output signal of the sensor is inverted, amplified, and then levelshifted by an adjustable offset voltage (through r offset1 ). the offset voltage is adjusted to produce 0.5 volts at the maximum barometric pressure (30.5 inhg.). the output voltage will increase for decreasing pressure. if the output exceeds 5.1 v, a zener protection diode will clamp the output. this feature is included to protect the a/d channel input of the mcu. using the transfer function for this circuit, the offset voltage and gain can be determined to provide 0.1 inhg of system resolution and the desired output voltage level. the calculation of these parameters is illustrated below. in determining the amplifier gain and range of the trimmable offset voltage, it is necessary to calculate the number of steps used in the a/d conversion process to resolve 0.1 inhg. ( 30.5 15.0 ) in-hg * 10 steps hg 155 steps the span voltage can now be determined. the resolution provided by an 8bit a/d converter with low and high voltage references of zero and five volts, respectively, will detect 19.5 mv of change per step. v rh 5v, v rl 0v sensor output at 30.5 inhg = 32.44 mv sensor output at 15.0 inhg = 16.26 mv d sensor output = d so = 16.18 mv gain 3.04 v so 187 note: 30.5 inhg and 15.0 inhg are the assumed maximum and minimum absolute pressures, respectively. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3291 motorola sensor device data www.motorola.com/semiconductors this gain is then used to determine the appropriate resistor values and offset voltage for the amplifier circuit defined by the transfer function shown below. v out r 2 r 1 1 * v v off d v is the differential output of the sensor. the gain of 187 can be implemented with: r 1 r 3 = 121 w r 2 r 4 = 22.6 k w. choosing r offset1 to be 1 k w and r offset2 to be 2.5 k w, v out is 0.5 v at the presumed maximum barometric pressure of 30.5 inhg. the maximum pressure output voltage can be trimmed to a value other than 0.5 v, if desired via r offset1 . in addition, the trimmable offset resistor is incorporated to provide offset calibration if significant offset drift results from large weather fluctuations. the circuit shown in figure 3 employs an mc33272 (lowcost, lowdrift) dual operational amplifier ic. in order to control large supply voltage fluctuations, an 8 vdc regulator, mc78l08acp, is used. this design permits use of a battery for excitation. microcontroller interface the low cost of mcu devices has allowed for their use as a signal processing tool in many applications. the mcu used in this application, the mc68hc11, demonstrates the power of incorporating intelligence into such systems. the onchip resources of the mc68hc11 include: an 8 channel, 8bit a/d, a 16bit timer, an spi (serial peripheral interface synchronous), and sci (serial communications interface asynchronous), and a maximum of 40 i/o lines. this device is available in several package configurations and product variations which include additional ram, eeprom, and/or i/o capability. the software used in this application was developed using the mc68hc11 evb development system. the following software algorithm outlines the steps used to perform the desired digital processing. this system will convert the voltage at the a/d input into a digital value, convert this measurement into inches of mercury, and output this data serially to an lcd display interface (through the onboard spi). this process is outlined in greater detail below: 1. set up and enable a/d converter and spi interface. 2. initialize memory locations, initialize variables. 3. make a/d conversion, store result. 4. convert digital value to inches of mercury. 5. determine if conversion is in system range. 6a. convert pressure into decimal display digits. 6b. otherwise, display range error message. 7. output result via spi to lcd driver device. the signal conditioned sensor output signal is connected to pin pe5 (port ea/d input pin). the mcu communicates to the lcd display interface via the spi protocol. a listing of the assembly language source code to implement these tasks is included in the appendix. in addition, the software can be downloaded directly from the motorola mcu freeware bulletin board (in the mcu directory). further information is included at the beginning of the appendix. in ground out + 3 1 4 + +12 v u1 mc78l08acp v s = 8 v u2b mc33272 v out 5.1 v zener r4 22.6 k w c1 0.33 m f c2 0.33 m f mpxm2102as r offset1 1 k w r offset2 2.5 k w r2 22.6 k w r1 121 w u2a mc33272 r3 121 w s s+ 1 2 2 12 12 1 2 figure 3. signal conditioning circuit 1 2 1 2 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3292 motorola sensor device data www.motorola.com/semiconductors lcd interface in order to digitally display the barometric pressure conversion, a serial lcd interface was developed to communicate with the mcu. this system includes an mc145453 cmos serial interface/lcd driver, and a 4digit, nonmultiplexed lcd. in order for the mcu to communicate correctly with the interface, it must serially transmit six bytes for each conversion. this includes a start byte, a byte for each of the four decimal display digits, and a stop byte. for formatting purposes, decimal points and blank digits can be displayed through appropriate bit patterns. the control of display digits and data transmission is executed in the source code through subroutines bcdconv, lookup, sp12lcd, and transfer. a block diagram of this interface is included below. conclusion this digital barometer system described herein is an excellent example of a sensing system using solid state components and software to accurately measure barometric pressure. this system serves as a foundation from which more complex systems can be developed. the mpxm2102a series pressure sensors provide the calibration and temperature compensation necessary to achieve the desired accuracy and interface simplicity for barometric pressure sensing applications. mc68hc11 mosi sck digit1 digit2 digit3 digit4 bp bp v dd bp in bp out osc in out 33 data clock v ss out1 mc145453 +5 v 20 1 figure 4. lcd display interface diagram f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3293 motorola sensor device data www.motorola.com/semiconductors appendix mc68hc11 barometer software available on: motorola electronic bulletin board mcu freeware line 8bit, no parity, 1 stop bit 1200/300 baud (512) 891free (3733) * barometer applications project chris winkler * developed: october 1st, 1992 motorola discrete applications * this code will be used to implement an mc68hc11 microcontroller * as a processing unit for a simple barometer system. * the hc11 will interface with an mpx2100ap to monitor,store * and display measured barometric pressure via the 8bit a/d channel * the sensor output (32mv max) will be amplified to .5 2.5 v dc * the processor will interface with a 4digit lcd (fe202) via * a motorola lcd driver (mc145453) to display the pressure * within +/ one tenth of an inch of mercury. * the systems range is 15.0 30.5 inhg * a/d & cpu register assignment * this code will use index addressing to access the * important control registers. all addressing will be * indexed off of regbase, the base address for these registers. regbase equ $1000 * register base of control register adctl equ $30 * offset of a/d control register adr2 equ $32 * offset of a/d results register adopt equ $39 * offset for a/d option register location portb equ $04 * location of portb used for conversion portd equ $08 * portd data register index ddrd equ $09 * offset of data direction reg. spcr equ $28 * offset of spi control reg. spsr equ $29 * offset of spi status reg. spdr equ $2a * offset of spi data reg. * user variables * the following locations are used to store important measurements * and calculations used in determining the altitude. they * are located in the lower 256 bytes of user ram digit1 equ $0001 * bcd blank digit (not used) digit2 equ $0002 * bcd tens digit for pressure digit3 equ $0003 * bcd tenths digit for pressure digit4 equ $0004 * bcd ones digit for pressure counter equ $0005 * variable to send 5 dummy bytes poffset equ $0010 * storage location for max pressure offset sensout equ $0012 * storage location for previous conversion result equ $0014 * storage of pressure(in hg) in hex format flag equ $0016 * determines if measurement is within range * main program * the conversion process involves the following steps: * * 1. setup spi device spi_cnfg * 2. setup a/d, constants set_up * 3. read a/d, store sample adconv * 4. convert into inhg in_hg * 5. determine flag condition in_hg * a. display error error * b. continue conversion inrange * 6. convert hex to bcd format bcdconv * 7. convert lcd display digits lookup * 8. output via spi to lcd spi2lcd * this process is continually repeated as the loop convert * runs unconditionally through bra (the branch always statement) * repeats to step 3 indefinitely. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3294 motorola sensor device data www.motorola.com/semiconductors org $c000 * designates start of memory map for user code ldx #regbase * location of base register for indirect adr bsr spi_cnfg * setup spi module for data xmit to lcd bsr set_up * powerup a/d, initialize constants convert bsr adconv * calls subroutine to make an a/d conversion bsr delay * delay routine to prevent lcd flickering bsr in_hg * converts hex format to in of hg * the value of flag passed from in_hg is used to determine * if a range error has occurred. the following logical * statements are used to either allow further conversion or jump * to a routine to display a range error message. ldab flag * determines if an range error has ocurred cmpb #$80 * if no error detected (flag=$80) then beq inrange * system will continue conversion process bsr error * if error occurs (flag<>80), branch to error bra output * branches to output error code to display * no error detected, conversion process continues inrange jsr bcdconv * converts hex result to bcd jsr lookup * uses lookup table for bcddecimal output jsr spi2lcd * output transmission to lcd bra convert * continually converts using branch always * subroutine spi_cnfg * purpose is to initialize spi for transmission * and clear the display before conversion. spi_cnfg bset portd,x #$20 * set spi ss line high to prevent glitch ldaa #$38 * initializing data direction for port d staa ddrd,x * selecting ss, mosi, sck as outputs only ldaa #$5d * initialize spicontrol register staa spcr,x * selecting spe,mstr,cpol,cpha,cpro ldaa #$5 * sets counter to xmit 5 blank bytes staa counter ldaa spsr,x * must read spsr to clear spif flag clra * transmission of blank bytes to lcd eraselcd jsr transfer * calls subroutine to transmit dec counter bne eraselcd rts * subroutine set_up * purpose is to initialize constants and to powerup a/d * and to initialize poffset used in conversion purposes. set_up ldaa #$90 * selects adpu bit in option register staa adopt,x * powerup of a/d complete ldd #$0131+$001a * initialize poffset std poffset * poffset = 305 25 in hex ldaa #$00 * or pmax + offset voltage (5 v) rts * subroutine delay * purpose is to delay the conversion process * to minimize lcd flickering. delay lda #$ff * loop for delay of display outloop ldb #$ff * delay = clk/255*255 inloop decb bne inloop deca bne outloop rts * subroutine adconv * purpose is to read the a/d input, store the conversion into * sensout. for conversion purposes later. adconv ldx #regbase * loads base register for indirect addressing ldaa #$25 staa adctl,x * initializes a/d cont. register scan=1,mult=0 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3295 motorola sensor device data www.motorola.com/semiconductors wtconv brclr adctl,x #$80 wtconv * wait for completion of conversion flag ldab adr2,x * loads conversion result into accumulator clra std sensout * stores conversion as sensout rts * subroutine in_hg * purpose is to convert the measured pressure sensout, into * units of inhg, represented by a hex value of 305150 * this represents the range 30.5 15.0 inhg in_hg ldd poffset * loads maximum offset for subtraction subd sensout * result = poffsetsensout in hex format std result * stores hex result for p, in hg cmpd #305 bhi tohigh cmpd #150 blo tolow ldab #$80 stab flag bra end_conv tohigh ldab #$ff stab flag bra end_conv tolow ldab #$00 stab flag end_conv rts * subroutine error * this subroutine sets the display digits to output * an error message having detected an out of range * measurement in the main program from flag error ldab #$00 * initialize digits 1,4 to blanks stab digit1 stab digit4 ldab flag * flag is used to determine cmpb #$00 * if above or below range. bne set_hi * if above range goto set_hi ldab #$0e * else display lo on display stab digit2 * set digit2=l,digit3=o ldab #$7e stab digit3 bra end_err * goto exit of subroutine set_hi ldab #$37 * set digit2=h,digit3=1 stab digit2 ldab #$30 stab digit3 end_err rts * subroutine bcdconv * purpose is to convert altitude from hex to bcd * uses standard hexbcd conversion scheme * divide hex/10 store remainder, swap q & r, repeat * process until remainder = 0. bcdconv ldaa #$00 * default digits 2,3,4 to 0 staa digit2 staa digit3 staa digit4 ldy #digit4 * conversion starts with lowest digit ldd result * load voltage to be converted convlp ldx #$a * divide hex digit by 10 idiv * quotient in x, remainder in d stab 0,y * stores 8 lsb's of remainder as bcd digit dey cpx #$0 * determines if last digit stored xgdx * exchanges remainder & quotient bne convlp ldx #regbase * reloads base into main program rts * subroutine lookup f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3296 motorola sensor device data www.motorola.com/semiconductors * purpose is to implement a lookup conversion * the bcd is used to index off of table * where the appropriate hex code to display * that decimal digit is contained. * digit4,3,2 are converted only. lookup ldx #digit1+4 * counter starts at 5 tabloop dex * start with digit4 ldy #table * loads table base into ypointer ldab 0,x * loads current digit into b aby * adds to base to index off table ldaa 0,y * stores hex segment result in a staa 0,x cpx #digit2 * loop condition complete, digit2 converted bne tabloop rts * subroutine spi2lcd * purpose is to output digits to lcd via spi * the format for this is to send a start byte, * four digits, and a stop byte. this system * will have 3 significant digits: blank digit * and three decimal digits. * sending lcd start byte spi2lcd ldx #regbase ldaa spsr,x * reads to clear spif flag ldaa #$02 * byte, no colon, start bit bsr transfer * transmit byte * initializing decimal point & blank digit ldaa digit3 * sets msb for decimal pt. ora #$80 * after digit 3 staa digit3 ldaa #$00 * set 1st digit as blank staa digit1 * sending four decimal digits ldy #digit1 * pointer set to send 4 bytes dloop ldaa 0,y * loads digit to be xmitted bsr transfer * transmit byte iny * branch until both bytes sent cpy #digit4+1 bne dloop * sending lcd stop byte ldaa #$00 * end byte requires all 0's bsr transfer * transmit byte rts * subroutine transfer * purpose is to send data bits to spi * and wait for conversion complete flag bit to be set. transfer ldx #regbase bclr portd,x #$20 * assert ss line to start xmisssion staa spdr,x * load data into data reg.,xmit xmit brclr spsr,x #$80 xmit * wait for flag bset portd,x #$20 * disassert ss line ldab spsr,x * read to clear spi flag rts * location for fcb memory for lookup table * there are 11 possible digits: blank, 09 table fcb $7e,$30,$6d,$79,$33,$5b,$5f,$70,$7f,$73,$00 end f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3297 motorola sensor device data www.motorola.com/semiconductors "! " "
! ! " prepared by: brian pickard sensor products division semiconductor products sector introduction motorola offers a wide variety of ported, pressure sensing devices which incorporate a hose barb and mounting tabs. they were designed to give the widest range of design flexibility. the hose barbs are 1/8 ( 3 mm) diameter and the tabs have #6 mounting holes. these sizes are very common and should make installation relatively simple. more importantly, and often overlooked, are the techniques used in mounting and adapting the ported pressure sensors. this application note provides some recommendations on types of fasteners for mounting, how to use them with motorola sensors, and identifies some suppliers. this document also recommends a variety of hoses, hose clamps, and their respective suppliers. this information applies to all motorola mpx pressure sensors with ported packages, which includes the packages shown in figure 1. single side port differential port axial port stovepipe port figure 1. mpx pressure sensors with ported packages a review of recommended mounting hardware, mounting torque, hose applications, and hose clamps is also provided for reference. mounting hardware mounting hardware is an integral part of package design. different applications will call for different types of hardware. when choosing mounting hardware, there are three important factors: ? permanent versus removable ? application ? cost the purpose of mounting hardware is not only to secure the sensor in place, but also to remove the stresses from the sensor leads. in addition, these stresses can be high if the hose is not properly secured to the sensor port. screws, rivets, pushpins, and clips are a few types of hardware that can be used. refer to figure 2. pushpin rivet screw figure 2. mounting hardware

semiconductor application note rev 1 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3298 motorola sensor device data www.motorola.com/semiconductors figure 3. case outline drawings top: case 371d03, issue c bottom: case 35005, issue j notes: 1. dimensioning and tolerancing per ansi y14.5m, 1982. 2. controlling dimension: inch. dim min max min max millimeters inches a 1.080 1.120 27.43 28.45 b 0.740 0.760 18.80 19.30 c 0.630 0.650 16.00 16.51 d 0.016 0.020 0.41 0.51 e 0.160 0.180 4.06 4.57 f 0.048 0.064 1.22 1.63 g 0.100 bsc 2.54 bsc j 0.014 0.016 0.36 0.41 k n 0.070 0.080 1.78 2.03 p 0.150 0.160 3.81 4.06 q 0.150 0.160 3.81 4.06 r 0.440 0.460 11.18 11.68 s 0.695 0.725 17.65 18.42 u 0.840 0.860 21.34 21.84 v 0.182 0.194 4.62 4.92 e c j v t port #2 vacuum pin 1 4 pl d p g k m q m 0.25 (0.010) t u a f s n b s p m 0.13 (0.005) q s t q r 1234 positive pressure 0.220 0.240 5.59 6.10 seating plane b n r c j t d f u h l port #1 positive pressure pin 1 a q s k g 4 pl p s q m 0.25 (0.010) t s s m 0.13 (0.005) q s t 12 34 notes: 1. dimensioning and tolerancing per ansi y14.5, 1982. 2. controlling dimension: inch. dim min max min max millimeters inches a 1.145 1.175 29.08 29.85 b 0.685 0.715 17.40 18.16 c 0.305 0.325 7.75 8.26 d 0.016 0.020 0.41 0.51 f 0.048 0.064 1.22 1.63 g 0.100 bsc 2.54 bsc h 0.182 0.194 4.62 4.93 j 0.014 0.016 0.36 0.41 k 0.695 0.725 17.65 18.42 l 0.290 0.300 7.37 7.62 n 0.420 0.440 10.67 11.18 p 0.153 0.159 3.89 4.04 q 0.153 0.159 3.89 4.04 r 0.230 0.250 5.84 6.35 s u 0.910 bsc 23.11 bsc 0.220 0.240 5.59 6.10 to mount any of the devices except case 37107/08 and 867e) to a flat surface such as a circuit board, the spacing and diameter for the mounting holes should be made according to figure 3. mounting screws mounting screws are recommended for making a very secure, yet removable connection. the screws can be either metal or nylon, depending on the application. the holes are 0.155 diameter which fits a #6 machine screw. the screw can be threaded directly into the base mounting surface or go through the base and use a flat washer and nut (on a circuit board) to secure to the device. mounting torque the torque specifications are very important. the sensor package should not be over tightened because it can crack, causing the sensor to leak. the recommended torque specification for the sensor packages are as follows: port style torque range single side port: port side down port side up differential port (dual port) axial side port 34 inlb 67 inlb 9 10 in lb 9 10 in lb the torque range is based on installation at room temperature. since the sensor thermoplastic material has a higher tce (temperature coefficient of expansion) than common metals, the torque will increase as temperature increases. therefore, if the device will be subjected to very low temperatures, the torque may need to be increased slightly. if a precision torque wrench is not available, these torques all work out to be roughly 1/2 of a turn past afinger tighto (contact) at room temperature. tightening beyond these recommendations may damage the package, or affect the performance of the device. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3299 motorola sensor device data www.motorola.com/semiconductors nylon screws motorola recommends the use of #6 32 nylon screws as a hardware option. however, they should not be torqued excessively. the nylon screw will twist and deform under higher than recommended torque. these screws should be used with a nylon nut. rivets rivets are excellent fasteners which are strong and very inexpensive. however, they are a permanent connection. plastic rivets are recommended because metal rivets may damage the plastic package. when selecting a rivet size, the most important dimension, besides diameter, is the grip range. the grip range is the combined thickness of the sensor package and the thickness of the mounting surface. package thicknesses are listed below. port style thickness, a grip range = a + b single side port dual side port axial side port stovepipe port 0.321 (8.15 mm) 0.420 (10.66 mm) 0.321 (8.15 mm) (does not apply) a b pushpins plastic push pins or itw fastex achristmas treeo pins are an excellent way to make a low cost and easily removable connection. however, these fasteners should not be used for permanent connections. remember, the fastener should take all of the static and dynamic loads off the sensor leads. this type of fastener does not do this completely. hose applications by using a hose, a sensor can be located in a convenient place away from the actual sensing location which could be a hazardous and difficult area to reach. there are many types of hoses on the market. they have different wall thicknesses, working pressures, working temperatures, material compositions, and media compatibilities. all of the hoses referenced here are 1/8 inside diameter and 1/16 wall thickness, which produces a 1/4 outside diameter. since all the port hose barbs are 1/8 , they require 1/8 inside diameter hose. the intent is for use in air only and any questions about hoses for your specific application should be directed to the hose manufacturer. four main types of hose are available: ? vinyl ? tygon ? urethane ? nylon vinyl hose is inexpensive and is best in applications with pressures under 50 psig and at room temperature. it is flexible and durable and should not crack or deteriorate with age. this type of hose should be used with a hose clamp such as those listed later in this application note. two brands of vinyl hose are: hose wall thickness max. press. @ 70 f (24 c) max. temp. ( f)/( c) clippard #38141 herco clear #0500037 1/16 1/16 105 54 100/(38) 180/(82) tygon tubing is slightly more expensive than vinyl, but it is the most common brand, and it is also very flexible. it also is recommended for use at room temperature and applications below 50 psig. this tubing is also recommended for applications where the hose may be removed and reattached several times. this tubing should also be used with a hose clamp. tubing wall thickness max. press. @ 73 f (25 c) max. temp. ( f)/( c) tygon b443 1/16 62 165/(74) urethane tubing is the most expensive of the four types described herein. it can be used at higher pressures (up to 100 psig) and temperatures up to 100 f (38 c). it is flexible, although its flexibility is not as good as vinyl or tygon. urethane tubing is very strong and it is not necessary to use a hose clamp, although it is recommended. two brands of urethane hose are: hose wall thickness max. press. @ 70 f (24 c) max. temp. ( f)/( c) clippard #38146 herco clear #0585037 1/16 1/16 105 105 120/(49) 225/(107) nylon tubing does not work well with motorola's sensors. it is typically used in high pressure applications with metal fittings (such as compressed air). hose clamps hose clamps should be employed for use with all hoses listed above. they provide a strong connection with the sensor which prevents the hose from working itself off, and also reduces the chance of leakage. there are many types of hose clamps that can be used with the ported sensors. here are some of the most common hose clamps used with hoses. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3300 motorola sensor device data www.motorola.com/semiconductors crimpon clamp nylon snap spring wire screwon figure 4. hose clamps the two clamps most recommended by motorola are the crimpon clamp and the screwon, clippard reusable clamp. the crimpon type clamp is offered from both ryan herco (#0929007) and clippard (#50002). once crimped in place, it provides a very secure hold, but it is not easily removed and is not reusable. the clippard, reusable hose clamp is a brass, selfthreading clamp, which provides an equally strong grip as the crimpon type just described. the drawback is the reusable clamp is considerably more expensive. the nylon snap is also reusable, however the size options do not match the necessary outside diameter. the spring wire clamp, common in the automotive industry, and known for its very low cost and ease of use, also has a size matching problem. custom fit spring wire clamps may provide some cost savings in particular applications. hoses nortonperformance plastics worldwide headquarters 150 dey road, wayne, nj 074704599 usa (201) 5964700 telex: 7109885834 usa p.o. box 3660, akron, oh 443093660 usa (216) 7989240 fax: (216) 7980358 clippard instrument laboratory, inc. 7390 colerain rd. cincinnati, ohio 45239, usa (513) 5214261 fax: (513) 5214464 ryan herco products corporation p.o. box 588 burbank, ca 91503 18004232589 fax: (818) 8424488 spring wire clamps rotorclip, inc. 187 davidson avenue somerset, nj 088750461 18006315857 ext. 255 rivets and pushpins itw fastex 195 algonquin road des plaines, il 60016 (708) 2992222 fax: (708) 3908727 bolts quality screw and nut company 1331 jarvis avenue elk grove village, il 60007 (312) 5931600 crimpon and nylon clamps ryan herco products corporation p.o. box 588 burbank, ca 91503 18004232589 fax: (818) 8424488 crimpon and screwon clamps clippard instrument laboratory, inc. 7390 colerain rd. cincinnati, ohio 45239, usa (513) 5214261 fax: (513) 5214464 supplier list f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3301 motorola sensor device data www.motorola.com/semiconductors prepared by: jc hamelain toulouse pressure sensor laboratory semiconductor products sector, toulouse, france introduction motorola discrete products provides a complete solution for designing a low cost system for direct and accurate liquid level control using an ac powered pump or solenoid valve. this circuit approach which exclusively uses motorola semiconductor parts, incorporates a piezoresistive pressure sensor with onchip temperature compensation and a new solidstate relay with an integrated power triac, to drive directly the liquid level control equipment from the domestic 110/220 v 50/60 hz ac main power line. pressure sensor description the mpxm2000 series pressure sensor integrates onchip, lasertrimmed resistors for offset calibration and temperature compensation. the pressure sensitive element is a patented, single piezoresistive implant which replaces the four resistor wheatstone bridge traditionally used by most pressure sensor manufacturers. mpak axial port case 1320a depending on the application and pressure range, the sensor may be chosen from the following portfolio. for this application the mpxm2010gs was selected. device pressure range application sensitivity* mpxm2010gs 0 to 10 kpa 0.01 kpa (1 mm h 2 o) mpxm2053gs 0 to 50 kpa 0.05 kpa (5 mm h 2 o) mpxm2102gs 0 to 100 kpa 0.1 kpa (10 mm h 2 o) mpxm2202gs 0 to 200 kpa 0.2 kpa (20 mm h 2 o) * after proper gain adjustment pin 3 r s1 r p xducer r off1 pin 2 pin 4 + v out v out laser trimmed onchip r s2 pin 1 r off2 + v s r1 r2 figure 1. pressure sensor mpxm2000 series

semiconductor application note rev 2 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3302 motorola sensor device data www.motorola.com/semiconductors power opto isolator moc2a60 description the moc2a60 is a new motorola power opto ? isolator and consists of a gallium arsenide, infrared emitting diode, which is optically coupled to a zerocross triac driver and a power triac. it is capable of driving a load of up to 2 a (rms) directly from a line voltage of 220 v (50/60 hz). zva * device schematic 1, 4, 5, 6, 8. no pin 1, 4, 5, 6, 2. led cathode 1, 4, 5, 6, 3. led anode 1, 4, 5, 6, 7. main terminal 1, 4, 5, 6, 9. main terminal * zero voltage activate circuit 9 7 3 2 case 417 plastic package figure 2. moc2a60 power opto isolator signal conditioning when a full range pressure is applied to the mpxm2010gs, it will provide an output of about 20 mv (at an 8 v supply). therefore, for an application using only a few percent of the pressure range, the available signal may be as low as a few hundred microvolts. to be useful, the sensor signal must be amplified. this is achieved via a true differential amplifier (a1 and a2) as shown in figure 4. the gain adj (500 ohm) resistor, r g , sets the gain to about 200. the differential output of this stage is amplified by a second stage (a3) with a variable offset resistor. this stage performs a differential to singleended output conversion and references this output to the adjustable offset voltage. this output is then compared to a voltage (v ref = 4 v at tp2) at the input of the third stage (a4). this last amplifier is used as an inverted comparator amplifier with hysteresis (schmitt trigger) which provides a logic signal (tp3) within a preset range variation of about 10% of the input (selected by the ratio r9/(r9 + r7). if the pressure sensor delivers a voltage to the input of the schmitt trigger (pin 13) lower than the reference voltage (pin 12), then the output voltage (pin 14) is high and the drive current for the power stage moc2a60 is provided. when the sensor output increases above the reference voltage, the output at pin 14 goes low and no drive current is available. the amplifier used is a motorola mc33179. this is a quad amplifier with large current output drive capability (more than 80 ma). output power stage for safety reasons, it is important to prevent any direct contact between the ac main power line and the liquid environment or the tank. in order to maintain full isolation between the sensor circuitry and the main power, the solidstate relay is placed between the low voltage circuit (sensor and amplifier) and the ac power line used by the pump and compressor. the output of the last stage of the mc33179 is used as a current source to drive the led (light emitting diode). the series resistor, r8, limits the current into the led to approximately 15 ma and guarantees an optimum drive for the power optotriac. the ld1 (mfoe76), which is an infrared light emitting diode, is used as an indicator to detect when the load is under power. the moc2a60 works like a switch to turn on or off the pump's power source. this device can drive up to 2 a for an ac load and is perfectly suited for the medium power motors (less than 500 watts) used in many applications. it consists of an optotriac driving a power triac and has a zerocrossing detection to limit the power line disturbance problems when fast switching selfic loads. an rc network, placed in parallel with the output of the solidstate relay is not required, but it is good design practice for managing large voltage spikes coming from the inductive load commutation. the load itself (motor or solenoid valve) is connected in series with the solidstate relay to the main power line. example of application: accurate liquid level monitoring the purpose of the described application is to provide an electronic system which maintains a constant liquid level in a tank (within 5 mm h 2 o). the liquid level is kept constant in the tank by an ac electric pump and a pressure sensor which provides the feedback information. the tank may be of any size. the application is not affected by the volume of the tank but only by the difference in the liquid level. of course, the maximum level in the tank must correspond to a pressure within the operating range of the pressure sensor. liquid level sensors motorola has developed a piezoresistive pressure sensor family which is very well adapted for level sensing, especially when using an air pipe sensing method. these devices may also be used with a bubbling method or equivalent. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3303 motorola sensor device data www.motorola.com/semiconductors open pipe before calibration control module pressure sensor air liquid level in the pipe electrical pump ac line reference level h figure 3. liquid level monitoring level sensing theory if a pipe is placed vertically, with one end dipped into a liquid and the other end opened, the level in the pipe will be exactly the same as the level in the tank. however, if the upper end of the pipe is closed off and some air volume is trapped, the pressure in the pipe will vary proportionally with the liquid level change in the tank. for example, if we assume that the liquid is water and that the water level rises in the tank by 10 mm, then the pressure in the pipe will increase by that same value (10 mm of water). a gauge pressure sensor has one side connected to the pipe (pressure side) and the other side open to ambient (in this case, atmospheric) pressure. the pressure difference which corresponds to the change in the tank level is measured by the pressure sensor. pressure sensor choice in this example, a level sensing of 10 mm of water is desired. the equivalent pressure in kilo pascals is 0.09806 kpa. in this case, motorola's temperature compensated 0 10 kpa, mpxm2010gs is an excellent choice. the sensor output, with a pressure of 0.09806 kpa applied, will result in 2.0 mv/kpa x 0.09806 = 0.196 mv. the sensing system is designed with an amplifier gain of about 1000. thus, the conditioned signal voltage given by the module is 1000 x 0.196 mv = 0.196 v with 10 mm h 2 o pressure. table 1. liquid level sensors method sensor advantage disadvantages liquid weight magnetoresitive low power, no active electronic low resolution, range limited magnetoresitive very high resolution complex electronic ultrasonic easy to install need high power, low accuracy liquid resistivity no active electronic no active electronic low resolution, liquid dependent string potentiometer potentiometer low power, no active electronic poor linearity, corrosion pressure silicon sensors inexpensive good resolution, wide range measurements active electronic, need power f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3304 motorola sensor device data www.motorola.com/semiconductors rg = 500 w r1, r2 = 100 k r5, r7 = 100 k r3, r4 . . . r6 = 10 k r9 . . . r11 = 10 k r8 = 100 r off = 25 k var a1 . . . a4 = 1/4 mc33179 d1 = mled76 mc7808ac = regl 8 vdc tr = transformer 220:12 v c1 = 40 m f 40 v offset adjust reference adj r off r10 r11 r9 r7 r3 r4 r2 r1 rg 32 4 1 5 6 + a2 a1 2 1 3+ 4 7 11 gain adj + + 10 9 8 tp1 tp2 + 12 13 a3 a4 14 tp3 r6 r8 d1 r c motor n p l tr 220 vac +8 vdc c1 mpxm2010gs r5 mc78l08 moc2a60 figure 4. electrical circuit liquid level pressure sensing (tp1) trigger voltage (tp3) pump voltage (ac220v) max min 7 v 0 4.3 v 0.4 v ref (tp2) 3.7 v sensing for minimum level (pumping into the tank) the sensing probe is tied to the positive pressure port of the sensor. the pump is turned on to fill the tank when the minimum level is reached. figure 5. functional diagram 10 mm f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3305 motorola sensor device data www.motorola.com/semiconductors level control modes this application describes two ways to keep the liquid level constant in the tank; first, by pumping the water out if the liquid level rises above the reference, or second, by pumping the water in if the liquid level drops below the reference. if pumping water out, the pump must be off when the liquid level is below the reference level. to turn the pump on, the sensor signal must be decreased to drop the input to the schmitt trigger below the reference voltage. to do this, the sensing pipe must be connected to the negative pressure port (back or vacuum side) of the sensor. in the condition when the pressure increases (liquid level rises), the sensor voltage will decrease and the pump will turn on when the sensor output crosses the referenced level. as pumping continues, the level in the tank decreases (thus the pressure on the sensor decreases) and the sensor signal increases back up to the trigger point where the pump was turned off. in the case of pumping water into the tank, the pump must be off when the liquid level is above the reference level. to turn on the pump, the sensor signal must be decreased to drive the input schmitt trigger below the reference voltage. to do this, the sensing pipe must be connected to the positive pressure port (top side) of the sensor. in this configuration when the pressure on the sensor decreases, (liquid level drops) the sensor voltage also decreases and the pump is turned on when the signal exceeds the reference. as pumping continues, the water level increases and when the maximum level is reached, the schmitt trigger turns the pump off. adjustments the sensing tube is placed into the water at a distance below the minimum limit level anywhere in the tank. the other end of the tube is opened to atmosphere. when the tank is filled to the desired maximum (or minimum) level, the pressure sensor is connected to the tube with the desired port configuration for the application. then the water level in the tank is the reference. after connecting the tube to the pressure sensor, the module must be adjusted to control the water level. the output voltage at tp1 is preadjusted to about 4 v (half of the supply voltage). when the sensor is connected to the tube, the module output is on (lighted) or off. by adjusting the offset adjust potentiometer the output is just turned into the other state: off, if it was on or the reverse, on, if it was off, (the change in the tank level may be simulated by moving the sensing tube up or down). the reference point tp2 shows the on/off reference voltage, and the switching point of the module is reached when the voltage at tp1 just crosses the value of the tp2 voltage. the module is designed for about 10 mm of difference level between on and off (hysteresis). conclusion this circuit design concept may be used to evaluate motorola pressure sensors used as a liquid level switch. this basic circuit may be easily modified to provide an analog signal of the level within the controlled range. it may also be easily modified to provide tighter level control ( 2 mm h 2 o) by increasing the gain of the first amplifier stage (decreasing rg resistor). the circuit is also a useful tool to evaluate the performance of the power optocoupler moc2a60 when driving ac loads directly. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3306 motorola sensor device data www.motorola.com/semiconductors prepared by: eric jacobsen and jeff baum sensor design and applications group, motorola phoenix, az introduction the pressure switch concept is simple, as are the additions to conventional signal conditioning circuitry required to provide a pressure threshold (or thresholds) at which the output switches logic state. this logiclevel output may be input to a microcontroller, drive an led, control an electronic switch, etc. the userprogrammed threshold (or reference voltage) determines the pressure at which the output state will switch. an additional feature of this minimal component design is an optional userdefined hysteresis setting that will eliminate multiple output transitions when the pressure sensor voltage is comparable to the threshold voltage. this paper presents the characteristics and design criteria for each of the major subsystems of the pressure switch design: the pressure sensor, the signal conditioning (gain) stage, and the comparator output stage. additionally, an entire section will be devoted to comparator circuit topologies which employ comparator ics and/or operational amplifiers. a window comparator design (high and low thresholds) is also included. this section will discuss the characteristics and design criteria for each comparator circuit, while evaluating them in overall performance (i.e., switching speed, logiclevel voltages, etc.). basic sensor operation motorola's mpx2000 series sensors are temperature compensated and calibrated (i.e., offset and fullscale span are precision trimmed) pressure transducers. these sensors are available in fullscale pressure ranges from 10 kpa (1.5 psi) to 200 kpa (30 psi). although the specifications (see table 1) in the data sheets apply only to a 10 v supply voltage, the output of these devices is ratiometric with the supply voltage. for example, at the absolute maximum supply voltage rating, 16 v, the sensor will produce a differential output voltage of 64 mv at the rated fullscale pressure of the given sensor. one exception to this is that the fullscale span of the mpx2010 (10 kpa sensor) will be only 40 mv due to the device's slightly lower sensitivity. since the maximum supply voltage produces the most output voltage, it is evident that even the best case scenario will require some signal conditioning to obtain a usable voltage level. for this specific design, an mpx2100 and 5.0 v supply is used to provide a maximum sensor output of 20 mv. the sensor output is then signal conditioned to obtain a four volt signal swing (span). table 1. mpx2100 electrical characteristics for v s = 10 v, t a = 25 c characteristic symbol minimum typical max unit pressure range p op 0 100 kpa supply voltage v s 10 16 vdc full scale span v fss 38.5 40 41.5 mv zero pressure offset v off 0.05 0.1 mv sensitivity s 0.4 mv/kpa linearity 0.05 %fss temperature effect on span 0.5 %fss temperature effect on offset 0.2 %fss

semiconductor application note rev 2 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3307 motorola sensor device data www.motorola.com/semiconductors the signal conditioning the amplifier circuitry, shown in figure 1, is composed of two opamps. this interface circuit has a much lower component count than conventional quad op amp instrumentation amplifiers. the two op amp design offers the high input impedance, low output impedance, and high gain desired for a transducer interface, while performing a differential to singleended conversion. the gain is set by the following equation: gain 1 r6 r5 where r6 r3 and r4 r5. for this specific design, the gain is set to 201 by setting r6 = 20 k w and r5 = 100 w . using these values and setting r6 = r3 and r4 = r5 gives the desired gain without loading the reference voltage divider formed by r1 and r off . the offset voltage is set via this voltage divider by choosing the value of r off . this enables the user to adjust the offset for each application's requirements. figure 1. pressure switch schematic amplifier stage comparator stage r1 12.1 k w r4 100 w r5 100 w r6 20 k w r off x1 mpx2100dp pressure sensor r th 10 k w r h 121 k w r10 24.3 k w r7 10.0 k w r11 4.75 k w q1 mmbt3904lt1 u1 u1 lm324d v th cn1 v out gnd +5 v v4 r3 20 k w u1 3 4 1 2 the comparison stage the comparison stage is the ahearto of the pressure switch design. this stage converts the analog voltage output to a digital output, as dictated by the comparator's threshold. the comparison stage has a few design issues which must be addressed: ? the threshold for which the output switches must be pro- grammable. the threshold is easily set by dividing the sup- ply voltage with resistors r7 and r th . in figure 1, the threshold is set at 2.5 v for r7 = r th = 10 k w . ? a method for providing an appropriate amount of hystere- sis should be available. hysteresis prevents multiple tran- sitions from occurring when slow varying signal inputs oscillate about the threshold. the hysteresis can be set by applying positive feedback. the amount of hysteresis is determined by the value of the feedback resistor, r h (refer to equations in the following section). ? it is ideal for the comparator's logic level output to swing from one supply rail to the other. in practice, this is not pos- sible. thus, the goal is to swing as high and low as possible for a given set of supplies. this offers the greatest differ- ence between logic states and will avoid having a micro- controller read the switch level as being in an indeterminate state. ? in order to be compatible with cmos circuitry and to avoid microcontroller timing delay errors, the comparator must switch sufficiently fast. ? by using two comparators, a window comparator may be implemented. the window comparator may be used to monitor when the applied pressure is within a set range. by adjusting the input thresholds, the window width can be customized for a given application. as with the single f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3308 motorola sensor device data www.motorola.com/semiconductors threshold design, positive feedback can be used to provide hysteresis for both switching points. the window compara- tor and the other comparator circuits will be explained in the following section. example comparator circuits several comparator circuits were built and evaluated. comparator stages using the lm311 comparator, lm358 opamp (with and without an output transistor stage), and lm339 were examined. each comparator was evaluated on output voltage levels (dynamic range), transition speed, and the relative component count required for the complete pressure switch design. this comparison is tabulated in table 2 . figure 2. lm311 comparator circuit schematic r h r2 v in r1 r pu v out u1 lm311 v cc lm311 used in a comparator circuit the lm311 chip is designed specifically for use as a comparator and thus has short delay times, high slew rate, and an open collector output. a pullup resistor at the output is all that is needed to obtain a railtorail output. additionally, the lm311 is a reverse logic circuit; that is, for an input lower than the reference voltage, the output is high. likewise, when the input voltage is higher than the reference voltage, the output is low. figure 2 shows a schematic of the lm311 stage with threshold setting resistor divider, hysteresis resistor, and the opencollector pullup resistor. table 2 shows the comparator's performance. based on its performance, this circuit can be used in many types of applications, including interface to microprocessors. the amount of hysteresis can be calculated by the following equations: v ref r2 r1 r2 v cc , neglecting the effect of r h . v refh r1r2 r2r h r1r2 r1r h r2r h v cc v refl r2r h r1r2 r1r h r2r h v cc hysteresis v ref v refl hysteresis v refh v ref when the normal state is below v ref ,or when the normal state is above v ref . table 2. comparator circuits performance characteristics characteristic lm311 lm358 lm358 w/ trans. unit switching speeds rise time 1.40 5.58 2.20 m s fall time 0.04 6.28 1.30 m s output levels v oh 4.91 3.64 5.00 v v ol 61.1 38.0 66.0 mv circuit logic type negative negative positive the initial calculation for v ref will be slightly in error due to neglecting the effect of r h . to establish a precise value for v ref (including r h in the circuit), recompute r1 taking into account that v ref depends on r1, r2, and r h . it turns out that when the normal state is below v ref , r h is in parallel with r1: v ref r2 r1 r h r2 v cc which is identical to the equation for v refh alternately, when the normal state is above v ref , r h is in parallel with r2: v ref r2 r h r1 r2 r h v cc which is identical to the equation for v refl these two additional equations for v ref can be used to calculate a more precise value for v ref . f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3309 motorola sensor device data www.motorola.com/semiconductors the user should be aware that v ref , v refh and v refl are chosen for each application, depending on the desired switching point and hysteresis values. also, the user must specify which range (either above or below the reference voltage) is the desired normal state (see figure 3). referring to figure 3, if the normal state is below the reference voltage then v refl (v refh is only used to calculate a more precise value for v ref as explained above) is below v ref by the desired amount of hysteresis (use v refl to calculate r h ). alternately, if the normal state is above the reference voltage then v refh (v refl is only used to calculate a more precise value for v ref ) is above v ref by the desired amount of hysteresis (use v refh to calculate r h ). an illustration of hysteresis and the relationship between these voltages is shown in figure 3. v ref (v refuw) v refl hysteresis hysteresis v refh v ref (vreflw) normal state figure 3. setting the reference voltages lm358 op amp used in a comparator circuit figure 4 shows the schematic for the lm358 op amp comparator stage, and table 2 shows its performance. since the lm358 is an operational amplifier, it does not have the fast slewrate of a comparator ic nor the open collector output. comparing the lm358 and the lm311 (table 2), the lm311 is better for logic/switching applications since its output nearly extends from rail to rail and has a sufficiently high switching speed. the lm358 will perform well in applications where the switching speed and logicstate levels are not critical (led output, etc.). the design of the lm358 comparator is accomplished by using the same equations and procedure presented for the lm311. this circuit is also reverse logic. lm358 op amp with a transistor output stage used in a comparator circuit the lm358 with a transistor output stage is shown in figure 5. this circuit has similar performance to the lm311 comparator: its output reaches the upper rail and its switching speed is comparable to the lm311's. this enhanced performance does, however, require an additional transistor and base resistor. referring to figure 1, note that this comparator topology was chosen for the pressure switch design. the lm324 is a quad op amp that has equivalent amplifier characteristics to the lm358. figure 4. lm358 comparator circuit schematic r h r2 v in r1 v out u1 lm358 v cc figure 5. lm358 with a transistor output stage comparator circuit schematic r h r2 v in r1 r pu v out u1 lm358 rb q1 mmbt3904lt1 v cc like the other two circuits, this comparator circuit can be designed with the same equations and procedure. the values for r b and r pu are chosen to give a 5:1 ratio in q1's collector current to its base current, in order to insure that q1 is wellsaturated (v out can pull down very close to ground when q1 is on). once the 5:1 ratio is chosen, the actual resistance values determine the desired switching speed for turning q1 on and off. also, r pu limits the collector current to be within the maximum specification for the given transistor (see example values in figure 1). unlike the other two circuits, this circuit is positive logic due to the additional inversion created at the output transistor stage. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3310 motorola sensor device data www.motorola.com/semiconductors lm339 used in a window comparator circuit using two voltage references to detect when the input is within a certain range is another possibility for the pressure switch design. the window comparator's schematic is shown in figure 6. the lm339 is a quad comparator ic (it has open collector outputs), and its performance will be similar to that of the lm311. figure 6. lm339 window comparator circuit schematic + + v in v out u1 lm339 v cc r pu r1 r hu r2 r4 r3 r hl v reflw r5 v refuw 1 2 1 2 2 1 21 1 2 1 2 2 1 4 5 6 7 1 2 2 1 u1 obtaining the correct amount of hysteresis and the input reference voltages is slightly different than with the other circuits. the following equations are used to calculate the hysteresis and reference voltages. referring to figure 3, v refuw is the upper window reference voltage and v reflw is the lower window reference voltage. remember that reference voltage and threshold voltage are interchangeable terms. for the upper window threshold: choose the value for v refuw and r1 (e.g., 10 k w ). then, by voltage division, calculate the total resistance of the combination of r2 and r3 (named r23 for identification) to obtain the desired value for v refuw , neglecting the effect of r hu : v refuw r23 r1 r23 v cc the amount of hysteresis can be calculated by the following equation: v refl r23r hu r1r23 r1r hu r23r hu v cc notice that the upper window reference voltage, v refuw , is now equal to its v refl value, since at this moment, the input voltage is above the normal state. hysteresis v refuw v refl , where vrefl is chosen to give the desired amount of hysteresis for the application. the initial calculation for v refuw will be slightly in error due to neglecting the effect of r hu . to establish a precise value for v refuw (including r hu in the circuit), recompute r1 taking into account that v refuw depends on r2 and r3 and the parallel combination of r1 and r hu . this more precise value is calculated with the following equation: v refuw r23 r1 r hu r23 v cc for the lower window threshold choose the value for v reflw. set v reflw r3 r1 r hu r2 r3 v cc , where r2 + r3 = r23 from above calculation. to calculate the hysteresis resistor: the input to the lower comparator is one half v in (since r4 = r5) when in the normal state. when v reflw is above one half of v in (i.e., the input voltage has fallen below the win- dow), r hl parallels r4, thus loading down v in . the resulting input to the comparator can be referred to as v inl (a lower in- put voltage). to summarize, when the input is within the win- dow, the output is high and only r4 is connected to ground from the comparator's positive terminal. this establishes one half of v in to be compared with v reflw . when the input volt- age is below v reflw , the output is low, and r hl is effectively in parallel with r4. by voltage division, less of the input voltage will fall across the parallel combination of r4 and r hl , de- manding that a higher input voltage at v in be required to make the noninverting input exceed v reflw . therefore the following equations are established: hysteresis v reflw v inl choose r4 = r5 to simplify the design. r hl r4r5 v reflw v inl v cc ( r4 r5 ) v inl v reflw important note: as explained above, because the input voltage is divided in half by r4 and r5, all calculations are done relative to the one half value of v in . therefore, for a hysteresis of 200 mv (relative to v in ), the above equations must use one half this hysteresis value (100 mv). also, if a v reflw value of 2.0 v is desired (relative to v in ), then 1.0 v for its value should be used in the above equations. the value for v inl should be scaled by one half also. the window comparator design can also be designed using operational amplifiers and the same equations as for the lm339 comparator circuit. for the best performance, however, a transistor output stage should be included in the design. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3311 motorola sensor device data www.motorola.com/semiconductors test/calibration procedure 1. before testing the circuit, the userdefined values for r th , r h and r off should be calculated for the desired application. the sensor offset voltage is set by v off v off r1 r off v cc . then, the amplified sensor voltage corresponding to a given pressure is calculated by v sensor = 201 x 0.0002 x applied pressure + v off , where 201 is the gain, 0.0002 is in units of v/kpa and applied pressure is in kpa. the threshold voltage, v th , at which the output changes state is calculated by determining v sensor at the pressure that causes this change of state: r th r7 r th v cc . v th = v sensor (@ pressure threshold) = if hysteresis is desired, refer to the lm311 used in a comparator section to determine r h . 2. to test this design, connect a +5 volt supply between pins 3 and 4 of the connector cn1. 3. connect a volt meter to pins 1 and 4 of cn1 to measure the output voltage and amplified sensor voltage, respectively. 4. connect an additional volt meter to the v th probe point to verify the threshold voltage. 5. turn on the supply voltage. 6. with no pressure applied, check to see that v off is correct by measuring the voltage at the output of the gain stage (the volt meter connected to pin 4 of cn1). if desired, v off can be fine tuned by using a potentiometer for r off . 7. check to see that the volt meter monitoring v th displays the desired voltage for the output to change states. use a potentiometer for r th to fine tune v th , if desired. 8. apply pressure to the sensor. monitor the sensor's output via the volt meter connected to pin 4 of cn1. the output will switch from low to high when this pressure sensor voltage reaches or exceeds the threshold voltage. 9. if hysteresis is used, with the output high (pressure sensor voltage greater than the threshold voltage), check to see if v th has dropped by the amount of hysteresis desired. a potentiometer can be used for r h to fine tune the amount of hysteresis. conclusion the pressure switch design uses a comparator to create a logic level output by comparing the pressure sensor output voltage and a userdefined reference voltage. the flexibility of this minimal component, high performance design makes it compatible with many different applications. the design presented here uses an op amp with a transistor output stage, yielding excellent logiclevel outputs and output transition speeds for many applications. finally, several other comparison stage designs, including a window comparator, are evaluated and compared for overall performance. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3312 motorola sensor device data www.motorola.com/semiconductors

prepared by: eric jacobsen and jeff baum sensor design and applications group, motorola phoenix, az introduction for remote sensing and noisy environment applications, a frequency modulated (fm) or pulse width modulated (pwm) output is more desirable than an analog voltage. fm and pwm outputs inherently have better noise immunity for these types of applications. generally, fm outputs are more widely accepted than pwm outputs, because pwm outputs are restricted to a fixed frequency. however, obtaining a stable fm output is difficult to achieve without expensive, complex circuitry. with either an fm or pwm output, a microcontroller can be used to detect edge transitions to translate the timedomain signal into a digital representation of the analog voltage signal. in conventional voltagetofrequency (v/f) conversions, a voltagecontrolled oscillator (vco) may be used in conjunction with a microcontroller. this use of two time bases, one analog and one digital, can create additional inaccuracies. with either fm or pwm outputs, the microcontroller is only concerned with detecting edge transitions. if a programmable frequency, stable pwm output could be obtained with simple, inexpensive circuitry, a pwm output would be a costeffective solution for noisy environment/remote sensing applications while incorporating the advantages of frequency outputs. the pulse width modulated output pressure sensor design (figure 1) utilizes simple, inexpensive circuitry to create an output waveform with a duty cycle that is linear to the applied pressure. combining this circuitry with a single digital time base to create and measure the pwm signal, results in a stable, accurate output. two additional advantages of this design are 1) an a/d converter is not required, and 2) since the pwm output calibration is controlled entirely by software, circuittocircuit variations due to component tolerances can be nullified. the pwm output sensor system consists of a motorola mpx5000 series pressure sensor, a ramp generator (transistor switch, constant current source, and capacitor), a comparator, and an mc68hc05p9 microcontroller. these subsystems are explained in detail below. figure 1. pwm output pressure sensor schematic pwm output to micro + 5.0 v pulse train from micro comparator stage ramp generator pressure sensor u1 lm311d c2 1.0 m f r5 22.1 k w r4 4.75 k w q1 mmbt3904lt1 c1 3.3 m f u2 mdc4010ct1 r1 10 k w r3 4.75 k w x1 mpx5100dp r2 10 k w semiconductor application note rev 1 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3313 motorola sensor device data www.motorola.com/semiconductors pressure sensor motorola's mpx5000 series sensors are signal conditioned (amplified), temperature compensated and calibrated (i.e., offset and fullscale span are precision trimmed) pressure transducers. these sensors are available in fullscale pressure ranges of 50 kpa (7.3 psi) and 100 kpa (14.7 psi). with the recommended 5.0 v supply, the mpx5000 series produces an output of 0.5 v at zero pressure to 4.5 v at full scale pressure. referring to the schematic of the system in figure 1, note that the output of the pressure sensor is attenuated to onehalf of its value by the resistor divider comprised of resistors r1 and r2. this yields a span of 2.0 v ranging from 0.25 v to 2.25 v at the noninverting terminal of the comparator. table 1 shows the electrical characteristics of the mpx5100. table 1. mpx5100dp electrical characteristics characteristic symbol min typ max unit pressure range p op 0 e 100 kpa supply voltage v s e 5.0 6.0 vdc full scale span v fss 3.9 4.0 4.1 v zero pressure offset v off 0.4 0.5 0.6 v sensitivity s e 40 e mv/kpa linearity e 0.5 e 0.5 %fss temperature effect on span e 1.0 e 1.0 %fss temperature effect on offset e 50 0.2 50 mv the ramp generator the ramp generator is shown in the schematic in figure 1. a pulse train output from a microcontroller drives the ramp generator at the base of transistor q1. this pulse can be accurately controlled in frequency as well as pulse duration via software (to be explained in the microcontroller section). the ramp generator uses a constant current source to charge the capacitor. it is imperative to remember that this current source generates a stable current only when it has approximately 2.5 v or more across it. with less voltage across the current source, insufficient voltage will cause the current to fluctuate more than desired; thus, a design constraint for the ramp generator will dictate that the capacitor can be charged to only approximately 2.5 v, when using a 5.0 v supply. the constant current charges the capacitor linearly by the following equation: v i t c ( 1 ) where d t is the capacitor's charging time and c is the capacitance. referring to figure 2, when the pulse train sent by the microcontroller is low, the transistor is off, and the current source charges the capacitor linearly. when the pulse sent by the microcontroller is high, the transistor turns on into saturation, discharging the capacitor. the duration of the high part of the pulse train determines how long the capacitor discharges, and thus to what voltage it discharges. this is how the dc offset of the ramp waveform may be accurately controlled. since the transistor saturates at approximately 60 mv, very little offset is needed to keep the capacitor from discharging completely. figure 2. ideal ramp waveform for the pwm output pressure sensor microcontroller pulse train exaggerated capacitor discharge ramp waveform ramp waveform offset (100 mv) f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3314 motorola sensor device data www.motorola.com/semiconductors the pwm output is most linear when the ramp waveform's period consists mostly of the rising voltage edge (see figure 2). if the capacitor were allowed to completely discharge (see figure 3), a flat line at approximately 60 mv would separate the ramps, and these aflat spotso may result in nonlinearities of the resultant pwm output (after comparing it to the sensor voltage). thus, the best ramp waveform is produced when one ramp cycle begins immediately after another, and a slight dc offset disallows the capacitor from discharging completely. exaggerated capacitor discharge figure 3. non ideal ramp waveform for the pwm output pressure sensor microcontroller pulse train ramp waveform the flexibility of frequency control of the ramp waveform via the pulse train sent from the microcontroller allows a programmablefrequency pwm output. using equation 1 the frequency (inverse of period) can be calculated with a given capacitor so that the capacitor charges to a maximum d v of approximately 2.5 v (remember that the current source needs approximately 2.5 v across it to output a stable current). the importance of software control becomes evident here since the selected capacitor may have a tolerance of 20%. by adjusting the frequency and positive width of the pulse train, the desired ramp requirements are readily obtainable; thus, nullifying the effects of component variances. for this design, the ramp spans approximately 2.4 v from 0.1 v to 2.5 v. at this voltage span, the current source is stable and results in a linear ramp. this ramp span was used for reasons which will become clear in the next section. in summary, complete control of the ramp is achieved by the following adjustments of the microcontrollercreated pulse train: ? increase frequency: span of ramp decreases. the dc offset decreases slightly. ? decrease frequency: span of ramp increases. the dc offset increases slightly. ? increase pulse width: the dc offset decreases. span decreases slightly. ? decrease pulse width: the dc offset increases. span increases slightly. the comparator stage the lm311 chip is designed specifically for use as a comparator and thus has short delay times, high slew rate, and an opencollector output. a pullup resistor at the output is all that is needed to obtain a railtorail output. as figure 1 shows, the pressure sensor output voltage is input to the noninverting terminal of the op amp and the ramp is input to the inverting terminal. therefore, when the pressure sensor voltage is higher than a given ramp voltage, the output is high; likewise, when the pressure sensor voltage is lower than a given ramp voltage, the output is low (refer to figure 5). as mentioned in the pressure sensor section, resistors r1 and r2 of figure 1 comprise the voltage divider that attenuates the pressure sensor's signal to a 2.0 v span ranging from 0.25 v to 2.25 v. since the pressure sensor voltage does not reach the ramp's minimum and maximum voltages, there will be a finite minimum and maximum pulse width for the pwm output. these minimum and maximum pulse widths are design constraints dictated by the comparator's slew rate. the system design ensures a minimum positive and negative pulse width of 20 m s to avoid nonlinearities at the high and low pressures where the positive duty cycle of the pwm output is at its extremes (refer to figure 4 ). depending on the speed of the microcontroller used in the system, the minimum required pulse width may be larger. this will be explained in the next section. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3315 motorola sensor device data www.motorola.com/semiconductors the microcontroller the microcontroller for this application requires input capture and output compare timer channels. the output capture pin is programmed to output the pulse train that drives the ramp generator, and the input capture pin detects edge transitions to measure the pwm output pulse width. since software controls the entire system, a calibration routine may be implemented that allows an adjustment of the frequency and pulse width of the pulse train until the desired ramp waveform is obtained. depending on the speed of the microcontroller, additional constraints on the minimum and maximum pwm output pulse widths may apply. for this design, the software latency incurred to create the pulse train at the output compare pin is approximately 40 m s. consequently, the microcontroller cannot create a pulse train with a positive pulse width of less than 40 m s. also, the software that measures the pwm output pulse width at the input capture pin requires approximately 20 m s to execute. referring to figure 5, the software interrupt that manipulates the pulse train always occurs near an edge detection on the input capture pin (additional software interrupt). therefore, the minimum pwm output pulse width that can be accurately detected is approximately 60 m s (20 m s + 40 m s). this constrains the minimum and maximum pulse widths more than the slew rate of the comparator which was discussed earlier (refer to figure 4). figure 4. desired relationship between the ramp waveform and pressure sensor voltage spans d v sets minimum pulse width (60 m s) v sfs v soff d v sets maximum pulse width (period 60 m s) an additional consideration is the resolution of the pwm output. the resolution is directly related to the maximum frequency of the pulse train. in our design, 512 m s are required to obtain at least 8bit resolution. this is determined by the fact that a 4 mhz crystal yields a 2 mhz clock speed in the microcontroller. this, in turn, translates to 0.5 m s per clock tick. there are four clock cycles per timer count. this results in 2 m s per timer count. thus, to obtain 256 timer counts (or 8bit resolution), the difference between the zero pressure and full scale pressure pwm output pulse widths must be at least 512 m s (2 m s x 256). but since an additional 60 m s is needed at both pressure extremes of the output waveform, the total period must be at least 632 m s. this translates to a maximum frequency for the pulse train of approximately 1.6 khz. with this frequency, voltage span of the ramp generator, and value of current charging the capacitor, the minimum capacitor value may be calculated with equation 1. to summarize: the mc68hc705p9 runs off a 4 mhz crystal. the microcontroller internally divides this frequency by two to yield an internal clock speed of 2 mhz. 1 2mhz 0.5 s clock cycle and, 4 clock cycles = 1 timer count. therefore, 4 clock cycles timer count 0.5 s clock cycle 2 s timer count for 8bit resolution, 2 s timer count 256 counts 512 s adding a minimum of 60 m s each for the zero and full scale pressure pulse widths yields 512 m s + 60 m s + 60 m s = 632 m s, which is the required minimum pulse train period to drive the ramp generator. translating this to frequency, the maximum pulse train frequency is thus 1 632 s 1.58 khz . f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3316 motorola sensor device data www.motorola.com/semiconductors calibration procedure and results the following calibration procedure will explain how to systematically manipulate the pulse train to create a ramp that meets the necessary design constraints. the numbers used here are only for this design example. figure 6 shows the linearity performance achieved by following this calibration procedure and setting up the ramp as indicated by figures 4 and 5. 1. start with a pulse train that has a pulse width and frequency that creates a ramp with about 100 mv dc offset and a span smaller than required. in this example the initial pulse width is 84 m s and the initial frequency is 1.85 khz. 2. decrease the frequency of the pulse train until the ramp span increases to approximately 2.4 v. the ramp span of 2.4 v will ensure that the maximum pulse width at full scale pressure will be at least 60 m s less than the total period. note that by decreasing the frequency of the pulse train, a dc offset will begin to appear. this may result in the ramp looking nonlinear at the top. 3. if the ramp begins to become nonlinear, increase the pulse width to decrease the dc offset. 4. repeat steps 2 and 3 until the ramp spans 2.4 v and has a dc offset of approximately 100 mv. the dc offset value is not critical, but the bottom of the ramp should have a acrispo point at which the capacitor stops discharging and begins charging. simply make sure that the minimum pulse width at zero pressure is at least 60 m s. refer to figures 4 and 5 to determine if the ramp is sufficient for the application. figure 5. relationships between the pwm output pressure sensor voltages microcontroller pulse train exaggerated capacitor discharge ramp waveform ramp waveform offset (100 mv) sensor voltage pwm output voltage figure 6. pwm output pressure sensor linearity data pressure (kpa) 100 90 80 70 60 50 40 30 20 10 0 650 600 550 500 450 400 350 300 250 200 150 100 50 0 0 20406080100 duty cycle pulse width duty cycle (%) pulse width ( s) m f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3317 motorola sensor device data www.motorola.com/semiconductors conclusion the pulse width modulated output pressure sensor uses a ramp generator to create a linear ramp which is compared to the amplified output of the pressure sensor at the input of a comparator. the resulting output is a digital waveform with a duty cycle that is linearly proportional to the input pressure. although the pressure sensor output has a fixed offset and span, the ramp waveform is adjustable in frequency, dc offset, and voltage span. this flexibility enables the effect of component tolerances to be nullified and ensures that ramp span encompasses the pressure sensor output range. the ramp's span can be set to allow for the desired minimum and maximum duty cycle to guarantee a linear dynamic range. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3318 motorola sensor device data www.motorola.com/semiconductors !
! prepared by: eric jacobsen and jeff baum sensor applications engineering motorola signal products division phoenix, az introduction although fully signalconditioned, calibrated, and temperature compensated monolithic sensor ic's are commercially available today, there are many applications where the flexibility of designing custom signalconditioning is of great benefit. perhaps the need for a versatile lowlevel sensor output is best illustrated by considering two particular cases that frequently occur: (1) the user is in a prototyping phase of development and needs the ability to make changes rapidly to the overall transfer function of the combined sensor/amplifier subsystem, (2) the specific desired transfer function does not exist in a fully signalconditioned, precisiontrimmed sensor product (e.g., a signalconditioned device is precision trimmed over a different pressure range than that of the application of interest). in such cases, it is obvious that there will always be a need for lowlevel, nonsignalconditioned sensors. given this need, there is also a need for sensor interface amplifier circuits that can signal condition the arawo sensor output to a usable level. these circuits should also be user friendly, simple, and cost effective. today's unamplified solidstate sensors typically have an output voltage of tens of millivolts (motorola's basic 10 kpa pressure sensor, mpx10, has a typical fullscale output of 58 mv, when powered with a 5 v supply). therefore, a gain stage is needed to obtain a signal large enough for additional processing. this additional processing may include digitization by a microcontroller's analog to digital (a/d) converter, input to a comparator, etc. although the signalconditioning circuits described here are applicable to lowlevel, differentialvoltage output sensors in general, the focus of this paper will be on interfacing pressure sensors to amplifier circuits. this paper presents a basic two operationalamplifier signalconditioning circuit that provides the desired characteristics of an instrumentation amplifier interface: ? high input impedance ? low output impedance ? differential to singleended conversion of the pressure sensor signal ? high gain capability for this two opamp circuit, additional modifications to the circuit allow (1) gain adjustment without compromising common mode rejection and (2) both positive and negative dc level shifts of the zero pressure offset. varying the gain and offset is desirable since fullscale span and zero pressure offset voltages of pressure sensors will vary somewhat from unit to unit. thus, a variable gain is desirable to fine tune the sensor's fullscale span, and a positive or negative dc level shift (offset adjustment) of the pressure sensor signal is needed to translate the pressure sensor's signalconditioned output span to a specific level (e.g., within the high and low reference voltages of an a/d converter). for the two opamp gain stage, this paper will present the derivation of the transfer function and simplified transfer function for pressure sensor applications, the derivation and explanation of the gain stage with a gain adjust feature, and the derivation and explanation of the gain stage with the dc level shift modification. adding another amplifier stage provides an alternative method of creating a negative dc voltage level shift. this stage is cascaded with the output from the two opamp stage ( note: gain of the two opamp stage will be reduced due to additional gain provided by the second amplifier stage). for this three opamp stage, the derivation of the transfer function, simplified transfer function, and the explanation of the negative dc level shift feature will be presented. general note on offset adjustment pressure sensor interface circuits may require either a positive or a negative dc level shift to adjust the zero pressure offset voltage. as described above, if the signalconditioned pressure sensor voltage is input to an a/d, the sensor's output dynamic range must be positioned within the high and low reference voltages of the a/d; i.e., the zero pressure offset voltage must be greater than (or equal to) the low reference voltage and the fullscale pressure voltage must be less than (or equal to) the high reference voltage (see figure 1). otherwise, voltages above the high reference will be digitally converted as 255 decimal (for 8bit a/d), and voltages below the low reference will be converted as 0. this creates a nonlinearity in the analogtodigital conversion. semiconductor application note f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3319 motorola sensor device data www.motorola.com/semiconductors figure 1. positioning the sensor's fullscale span within the a/d's or amplifier's dynamic range a/d high reference or high saturation level of amplifier fullscale output voltage a/d low reference or low saturation level of amplifier zero pressure offset voltage sensor's fullscale voltage span a/d's or amplifier's dynamic range a similar requirement that warrants the use of a dc level shift is the prevention of the pressure sensor's voltage from extending into the saturation regions of the operational amplifiers. this also would cause a nonlinearity in the sensor output measurements. for example, if an opamp powered with a singleended 5 v supply saturates near the low rail of the supply at 0.2 v, a positive dc level shift may be required to position the zero pressure offset voltage at or above 0.2 v. likewise, if the same opamp saturates near the high rail of the supply at 4.8 v, a negative dc level shift may be required to position the fullscale pressure voltage at or below 4.8 v. it should be obvious that if the gain of the amplifiers is too large, the span may be too large to be positioned within the 4.6 v window (regardless of ability to level shift dc offset). in such a case, the gain must be decreased to reduce the span. the two opamp gain stage transfer function the transfer function of the two opamp signalconditioning stage, shown in figure 2, can be determined using nodal analysis at nodes 1 and 2. the analysis can be simplified by calculating the transfer function for each of the signals with the other two signals grounded (set to zero), and then employing superposition to realize the overall transfer function. as shown in figure 2, v in2 and v in1 are the differential amplifier input signals (with v in2 > v in1 ), and v ref is the positive dc level adjust point. for a sensor with a small zero pressure offset and operational amplifiers powered from a singleended supply, it may be necessary to add a positive dc level shift to keep the operational amplifiers from saturating near zero volts. figure 2. the two operationalamplifier gain stage v in2 v in1 v ref node 1 r 1 r 2 r 4 r 3 v cc node 2 u 1 v o v o u 1 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3320 motorola sensor device data www.motorola.com/semiconductors first, the transfer function for v in1 is determined by grounding v ref and v in2 at node 1: v in1 r 1 = v o v in1 r 2 (1) and at node 2: v o r 3 = v o r 4 (2) by solving equations (1) and (2) for v o and equating the results, equation (3) is established: r 2 r 1 1 v in1 = r 3 r 4 v o (3) solving for v o yields v o1 = r 4 r 3 r 2 r 1 1 v in1 (4) where v o1 represents the part of v o that v in1 contributes. to determine the transfer function for v in2 , v in1 and v ref are grounded, and a similar analysis is used, yielding v o2 = r 4 r 3 1 v in2 (5) where v o2 represents the part of v o that v in2 contributes. finally, to calculate the transfer function between v o and v ref , v in1 and v in2 are grounded to obtain the following transfer function: v oref = r 4 r 2 r 3 r 1 v ref (6) where v oref represents the part of v o that v ref contributes. using superposition for the contributions of v in1 , v in2 , and v ref gives the overall transfer function for the signal conditioning stage. v o = v o1 + v o2 + v oref v o = r 4 r 3 r 2 r 1 1 v in1 + r 4 r 3 1 v in2 + r 4 r 2 r 3 r 1 v ref (7) equation (7) is the general transfer function for the signalconditioning stage. however, the general form is not only cumbersome, but also if no care is taken to match certain resistance ratios, poor common mode rejection results. a simplified form of this equation that provides good common mode rejection is shown in the next section. application to pressure sensor circuits the previous section showed the derivation of the general transfer function for the two opamp signalconditioning circuit. the simplified form of this transfer function, as applied to a pressure sensor application, is derived in this section. for pressure sensors, v in1 and v in2 are referred to as s and s + , respectively. the simplification is obtained by setting r 4 r 3 = r 1 r 2 through this simplification, equation (7) simplifies to v o = r 4 r 3 1 ( s + s ) + v ref (8) by examining equation (8), the differential gain of the signal conditioning stage is: g = r 4 r 3 + 1 (9) also, since the differential voltage between s + and s is the pressure sensor's actual differential output voltage (v sensor ), the following equation is obtained for v o : v o = r 4 r 3 1 v sensor + v ref (10) finally, the term v ref is the positive offset voltage added to the amplified sensor output voltage. v ref can only be positive when using a positive singleended supply. this offset (dc level shift) allows the user to adjust the absolute range that the sensor voltage spans. for example, if the gain established by r 4 and r 3 creates a span of four volts and this signal swing is superimposed upon a dc level shift (offset) of 0.5 volts, then a signal range from 0.5 v to 4.5 v results. v ref is typically adjusted by a resistor divider as shown in figure 3. a few design constraints are required when designing the resistor divider to set the voltage at v ref . ? to establish a stable positive dc level shift (v ref ), v cc should be regulated; otherwise, v ref will vary as v cc va- ries. ? when alookingo into the resistor divider from r 1 , the effec- tive resistance of the parallel combination of the resistors, r ref1 and r ref2 , should be at least an order of magni- tude smaller than r 1 's resistance. if the resistance of the parallel combination is not small in comparison to r 1 , r 1 's value will be significantly affected by the parallel combina- tion's resistance. this effect on r 1 will consequently affect the amplifier's gain and reduce the common mode rejec- tion. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3321 motorola sensor device data www.motorola.com/semiconductors figure 3. a resistor divider to create v ref r 1 v ref to u 1 v cc r ref1 r ref2 the two opamp gain stage with variable gain varying the gain of the two opamp stage is desirable for finetuning the sensor's signalconditioned output span. however, to adjust the gain in the two opamp gain circuit in figure 2 and to simultaneously preserve the common mode rejection, two resistors must be adjusted. to adjust the gain, it is more desirable to change one resistor. by adding an additional feedback resistor, r g , the gain can be adjusted with this one resistor while preserving the common mode rejection. figure 4 shows the two opamp gain stage with the added resistor, r g . figure 4. two operationalamplifier gain stage with variable gain v in2 v in1 v ref node 1 r 1 r 2 r 4 r 3 v cc node 2 u 1 v o u 1 r g v o as with the two opamp gain stage, nodal analysis and superposition are used to derive the general transfer function for the variable gain stage. v o = r 4 r 3 r 4 r g r 2 r 4 r 3 r g 1 v in2 r 4 r 3 r 4 r g r 2 r 4 r 3 r g r 2 r 4 r 1 r 3 v in1 + r 2 r 4 r 1 r 3 v ref (11) this general transfer function also is quite cumbersome and is susceptible to producing poor common mode rejection without additional constraints on the resistor values. to obtain good common mode rejection, use a similar simplification as before; that is, set r 1 = r 4 and r 2 = r 3 defining the voltage differential between v in2 and v in1 as v sensor , the simplified transfer function is v o = r 4 r 3 2r 4 r g 1 (v sensor ) + v ref (12) thus, the gain is g = r 4 r 3 + 2r 4 r g + 1 (13) and v ref is the positive dc level shift (offset). use the following guidelines when determining the value for r g : ? by examining the gain equation, r g 's resistance should be comparable to r 4 's resistance. this will allow fine tun- ing of the gain established by r 4 and r 3 . if r g is too large (e.g., r g approaches ), it will have a negligible effect on the gain. if r g is too small (e.g., r g approaches zero), the r g term will dominate the gain expression, thus prohibit- ing fine adjustment of the gain established via the ratio of r 4 and r 3 . ? use a potentiometer for r g that has a resistance range on the order of r 4 (perhaps with a maximum resistance equal to the value of r 4 ). if a fixed resistor is preferable to a poten- tiometer, use the potentiometer to adjust the gain, measure the potentiometer's resistance, and replace the potentiom- eter with the closest 1% resistor value. ? to maintain good common mode rejection while varying the gain, r g should be the only resistor that is varied. r g equally modifies both of the resistor ratios which need to be wellmatched for good common mode rejection, thus pre- serving the common mode rejection. the two opamp gain stage with variable gain and negative dc level shift the last two opamp circuits both incorporate positive dc level shift capability. recall that a positive dc level shift is required to keep the operational amplifiers from saturating near the low rail of the supply or to keep the zero pressure offset above (or equal to) the low reference voltage of an a/d. this two opamp stage incorporates an additional resistor, r off , to provide a negative dc level shift. a negative dc level shift is useful when the zero pressure offset voltage of the sensor is too high. in this case, the user may be required to level shift the zero pressure offset voltage down (toward zero volts). now, for a specified amount of gain, the fullscale pressure output voltage does not saturate the amplifier at the high rail of the voltage supply, nor is it greater than the a/d's high reference voltage. figure 5 shows the schematic for this amplifier circuit. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3322 motorola sensor device data www.motorola.com/semiconductors figure 5. two opamp signalconditioning stage with variable gain and negative dc level shift adjust v in2 v in1 v ref node 1 r 1 r 2 r 4 r 3 v cc node 2 u 1 v o v o u 1 r g r off to derive the general transfer function, nodal analysis and superposition are used: v o = r 4 r 3 r 4 r g r 2 r 4 r 3 r g 1 v in2 r 4 r 3 r 4 r g r 2 r 4 r 1 r 3 r 2 r 4 r 3 r g v in1 + r 2 r 4 r 1 r 3 v ref + r 4 r off (v in2 v cc ) (14) as before, defining the sensor's differential output as v sensor , defining v in2 as s + for pressure sensor applications, and using the s implification that r 1 = r 4 and r 2 = r 3 obtains the following simplified transfer function: v o = r 4 r 3 2r 4 r g 1 (v sensor ) + v ref + r 4 r off (s + v cc ) (15) the gain is g = r 4 r 3 + 2r 4 r g + 1 (16) to adjust the gain, refer to the guidelines presented in the section on two opamp gain stage with variable gain . v ref is the positive dc level shift, and the negative dc level shift is: v shift = r 4 r off (s + v cc ) (17) the following guidelines will help design the circuitry for the negative dc voltage level shift: ? to establish a stable negative dc level shift, v cc should be regulated; otherwise, the amount of negative level shift will vary as v cc varies. ? r off should be the only resistor varied to adjust the negative level shift. varying r 4 will change the gain of the two opamp circuit and reduce the common mode rejec- tion. ? to determine the value of r off : 1. determine the amount of negative dc level shifting re- quired (defined here as v shift ). 2. r 4 already should have been determined to set the gain for the desired signalconditioned sensor output. 3. although v shift is dependent on s + , s + changes only slightly over the entire pressure range. with motorola's mpx10 powered at a 5 v supply, s + will have a value of approximately 2.51 v at zero pressure and will increase as high as 2.53 v at fullscale pressure. this error over the fullscale pressure span of the device is negligible when considering that many applications use an 8bit a/d converter to segment the pressure range. using an 8bit a/d, the 20 mv (0.02 v) error corresponds to only 1 bit of error over the entire pressure range (1 bit / 255 bits x 100% = 0.4% error). 4. r off is then calculated by the following equation: r off = s + v cc v shift r 4 (18) an alternative to using this equation is to use a potentiometer for r off that has a resistance range on the order of r 4 (perhaps 1 to 5 times the value of r 4 ). use the potentiometer to fine tune the negative dc level shift, while monitoring the zero pressure offset output voltage, v o . as before, if a fixed resistor is preferable, then measure the potentiometer's resistance and replace the potentiometer with the closest 1% resistor value. important note: the common mode rejection of this amplifier topology will be low and perhaps unacceptable in some applications. (a spice model of this amplifier topology showed the common mode rejection to be 28 db.) however, this circuit is presented as a solution for applications where only two operational amplifiers are available and the common mode rejection is not critical when considering the required f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3323 motorola sensor device data www.motorola.com/semiconductors system performance. adding a third opamp to the circuit for the negative dc level shifting capability (as shown in the next section) is a solution that provides good common mode rejection, but at the expense of adding an additional opamp. the three opamp gain stage for negative dc level shifting this circuit adds a third opamp to the output of the two opamp gain block (see figure 6). this opamp has a dual function in the overall amplifier circuit: ? its noninverting configuration provides gain via the ratio of r 6 and r 5 . ? it has negative dc voltage level shifting capability typically created by a resistor divider at v shift , as discussed in the section on application to pressure sensor circuits. al- though this configuration requires a third opamp for the negative dc level shift, it has no intrinsic error nor low com- mon mode rejection associated with the negative level shift (as does the previous two opamp stage). depending on the application's accuracy requirement, this may be a more desirable configuration for providing the negative dc level shift. first, use the same simplifications as before; that is, set r 1 = r 4 and r 2 = r 3 defining the voltage differential between v in2 and v in1 as v sensor , the simplified transfer function is v o = 1 r 6 r 5 r 4 r 3 2r 4 r g 1 v sensor + v ref r 6 r 5 v shift (20) the gain is g = 1 r 6 r 5 r 4 r 3 2r 4 r g 1 (21) v ref is the positive dc level shift (offset), and v shift is the negative dc level shift. figure 6. three opamp gain stage with variable gain and negative dc level shift v in2 v in1 v ref r 1 r 2 r 4 r 3 v cc u 1 v o u 1 r g v o v o v shift r 5 r 6 u 1 the transfer function for this stage will be similar to the chosen two opamp gain stage configuration (either the fixed gain with positive dc level shift circuit or the variable gain with positive dc level shift circuit) with additional terms for the negative level shift and gain. as an example, the variablegain two opamp gain circuit is used here. all of the design considerations and explanations for the variable gain two opamp circuit apply. the transfer function may be derived with nodal analysis and superposition. v o = 1 r 6 r 5 r 4 r 3 r 4 r g r 2 r 4 r 3 r g 1 v in2 r 4 r 3 r 4 r g r 2 r 4 r 3 r g r 2 r 4 r 1 r 3 v in1 + r 2 r 4 r 1 r 3 v ref r 6 r 5 v shift (19) the preceding simplifications have been performed in the previous sections, but by examining equation 20, notice that the third opamp's gain term also amplifies the positive and negative dc voltage level shifts, v ref and v shift . if r 6 and r 5 are chosen to make an arbitrary contribution to the overall system gain, designing an appropriate amount of positive and negative dc level shift can be difficult. to simplify the transfer function, set r 5 = r 6 , and the following equation for v o results: v o = 2 r 4 r 3 2r 4 r g 1 v sensor v ref v shift (22) now the third opamp's contribution to the overall system gain is a factor of two. when designing the overall system gain and the positive dc level shift, use the following guidelines: f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3324 motorola sensor device data www.motorola.com/semiconductors ? since the third opamp contributes a gain of two to the overall system, design the gain that the two opamp circuit contributes to the system to be onehalf the desired sys- tem gain. the gain term for the two opamp circuit is: g = r 4 r 3 + 2r 4 r g + 1 which is the same as presented in equation 16. ? similarly, since the third opamp also amplifies v ref by two (refer to equation 22), the resistor divider that creates v ref should be designed to provide onehalf the desired positive dc voltage level shift needed for the final output. when designing the voltage divider for v ref , use the same design constraints as were given in the section on applica- tion to pressure sensor circuits. with the above simplification of r 5 = r 6 , the negative dc level shift, v shift , which is also created by a voltage divider, is now amplified by a factor of unity. when designing the voltage divider, use the same design constraints as were presented in the section on application to pressure sensor circuits. conclusion the amplifier circuits discussed in this paper apply to pressure sensor applications, but the amplifier circuits can be interfaced to lowlevel, differentialvoltage output sensors, in general. all of the circuits exhibit the desired instrumentation amplifier characteristics of high input impedance, low output impedance, high gain capability, and differential to singleended conversion of the sensor signal. each amplifier circuit provides positive dc level shift capability, while the last two circuit topologies presented are also able to provide a negative dc voltage level shift. this enables the user to position the sensor's dynamic output within a specified range (e.g., within the high and low references of an a/d converter). also detailed is a method of using an additional feedback resistor to adjust easily the differential voltage gain, while not sacrificing common mode rejection. combining the appropriate sensor device and amplifier interface circuit provides sensor users with a versatile system solution for applications in which the ideal fully singleconditioned sensor does not exist or in which such signal flexibility is warranted. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3325 motorola sensor device data www.motorola.com/semiconductors prepared by: bill lucas industrial technology center introduction this application note describes a digital boat speedometer concept which uses a monolithic, temperature compensated silicon pressure sensor, analog signalconditioning circuitry, microcontroller hardware/software and a liquid crystal display. this sensing system converts water head pressure to boat speed. this speedometer design using a 30 psi pressure sensor (motorola p/n: mpxm2202gs) yields a speed range of 5 mph to 45 mph. calibration of the system is performed using data programmed into the microcontroller's internal memory. a key advantage in all motorola pressure sensors is the patented xducer ? , a single piezoresistive implant that replaces the traditional wheatstone bridge configuration used by competitors. in addition to the xducer, motorola integrates onchip all necessary temperature compensation, eliminat- ing the need for separate substrates/hybrids. this stat eof theart tec hnology yields superior performance and reliability. motorola pressure sensors are offered in several different port configurations to allow measurement of absolute, differential and gauge pressure. motorola offers three pressure sensor types: uncompensated, temperature compensated and calibrated or fully signal conditioned. water pressure to boat speed conversion a typical analog boat speedometer employs a pitot tube, a calibrated pressure gauge/speedometer and a hose to connect the two. the pitot tube, located at the boat transom, provides the pressure signal corresponding to boat speed. this pressure signal is transmitted to the gauge via the hose. boat speed is related to the water pressure at the pitot tube as described by the following equation: p e*(v 2 2g) where: v = speed p = pressure at pitot tube e = specific weight of media g = gravitational acceleration for example, to calculate p in lb/in 2 for an ocean application use: v = speed in mph e = 63.99 lbs/ft 3 at 60 f, seawater (e will be smaller for fresh water) g = 32 ft/sec 2 15 mph = 22 ft/sec 1 ft 2 = 144 in 2 p (63.99[lb ft 3 ] 144[in 2 ft 2 ]) (v 2 [mph] 2 (22 15) 2 [(ft sec) mph] 2 2 (32.2)[ft sec 2 ]) p[psi] v 8.208 2 for example, if the boat is cruising at 30 mph, the impact pressure on the pitot tube is: p (30 8.208) 2 13.36 psi. digital boat speedometer description and operation the mpxm2202gs senses the impact water pressure against the pitot tube and outputs a proportional differential voltage signal. this differential voltage signal is then fed (via an analog switch and gain circuitry) to a single slope analogtodigital converter (a/d) which is external to the microcontroller. the a/d circuit can complete two separate conversions as well as a reference conversion simultaneous- ly. this a/d utilizes the microcontroller's internal timers as counters and software to properly manipulate the data. the analog switch provides a way to flip the sensor outputs after an a/d conversion step, which is necessary to null out the offset effects of the opamps. this is accomplished by performing an analog conversion, reversing the sensor's differential output signal, performing another analog conver- sion, summing the two readings, then dividing this sum by two. any opamp offset present will be the same polarity regardless of the sensor output polarity, thus the opamp offset can be mathematically nulled out. the digital representation of any analog signal is ratiometric to the reference voltages of the a/d converter. also, the sensor's output is ratiometric to its excitation voltage. therefore, if both the sensor and a/d reference voltages are connected to the same unregulated supply, the variations in sensor output will be nullified, and system accuracy will be maintained (i.e., systems in which both the a/d converter's digital value e due to variations in the a/d's reference voltages e and sensor's output voltage are ratiometric to the supply voltage so that a voltage regulator is not necessary).
semiconductor application note f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3326 motorola sensor device data www.motorola.com/semiconductors figure 1 shows the pressure sensor (xdcr) connected to the analog switches of the 74hc4053 which feeds the differential signal to the first stage of opamps. an a/d conversion is performed on the two opamp output signals, v out1 and v out2 . the difference (v out1 v out2 ) is com- puted and stored in microcontroller memory. the analog switch commutates (opamp connections switch from y 0 and z 0 to y 1 and z 1 ), reversing the sensor output signals to the two opamps, and another conversion is performed. this value is then also stored in the microcontroller memory. to summarize, via software, the following computation takes place: step 1: v first = v out1 v out2 step 2: v second = v out2 v out1 step 3: v result = (v first + v second ) / 2 again, because any opamp offset will remain the same polarity regardless of sensor output polarity, this routine will effectively cancel any amplifier offset. any offset the sensor may introduce is compensated for by software routines that are invoked when the initial system calibration is done. the single slope a/d provides 11 or more unsigned bits of resolution. this capability provides a water pressure resolution to at least 0.05 psi. this translates to a boat speed resolution of 0.1 mph over the entire speed range. figure 2 describes the pressure versus voltage transfer function of the first opamp stage. figure 1. xducer, instrument amplifier and analog switch + 33078 + 33078 mpxm2202gs 74hc4053 y0 y1 z0 z1 32 41 2 1 5 3 11 12 13 9 10 +8 + 8 7 616 +5 15 4 5 3 2 6 7 1 8 4 +8 v out1 v out2 denotes analog ground denotes logic ground xdcr input reverse control 10 k 10 k 22 pf 22 pf 316 k 316 k 10 k figure 2. instrument amplifier transfer function 8 6 4 2 0 0 10 20 30 psi pressure in u31 (u37) volts out u37 (u31) figure 3 details the analog circuitry, microcontroller's timer capture registers and i/o port which comprise the single slope a/d. the microcontroller's 16bit free running counter is also employed, but not shown in the figure. comparators u6a, u6b and u6d of the lm139a are used to provide the a/d function. constant current source, u7, resistors r13 and r14 and diode d2 provide a linear voltage ramp to the inverting inputs of u6, with about 470 microamps charge current to capacitor c8, with transistor q1 in the off state. c8 will charge to 5 volts in about 5 milliseconds at the given current. q1 is turned on to provide a discharge path for c8 when required. the circuit is designed such that when the voltage to the inverting inputs of the comparators exceeds the voltage to the noninverting comparators, each comparator output will trip from a logic 1 to a logic 0. one a/d conversion consists of the following steps: (1) setting the pressure sensor output polarity (via software and the analog switches of u4) to the amplifier inputs of the mc33078 (u3), (2) reading the value of the free running f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3327 motorola sensor device data www.motorola.com/semiconductors counter, (3) turning off q1, and (4) charging c8 and waiting for the three (u6) comparator outputs to change from 1 to 0. when the comparator outputs change state, the microcontroller free running counter value is clocked into the microcontroller's input capture register. contained in this register then is the number of counts required to charge c8 to a value large enough to trip the comparators. via software, the voltage signal from u3 (corresponding to the applied pressure signal) can be compared to the areference.o the boat speed display for this design employs an mc145453 lcd driver and fourdigit liquid crystal display, of which three digits and a decimal point are used. figure 4 shows the connections between the display driver and the display. the display driver is connected to the microprocessor's serial peripheral interface (spi). the software necessary to initialize, format and drive the lcd is included in the software listing contained in this article. figure 3. analogtodigital converter front end with microcontroller + lm139a + lm139a + lm139a input capture register 1 general purpose output input capture register 2 input capture register 3 +8 lm334z3 u7 d2 (approx. 470 m a) 1n914 r13 147 w r14 1.5 k 5% r12 4.7 w 5% 2n7000 q1 c8 0.47 m f polycarbonate 10 11 8 9 4 5 13 14 2 32 27 33 34 +5 r10 10 k 5% r11 10 k 5% +8 3 1/4 u6c r9 10 k 5% 1/4 u6b 1/4 u6a from u37 from u31 12 v ref (approx. 4.5 v) ic1 (pa2) pa7 ic2 (pa1) ic3 (pa0) mc68hc711e9 +5 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3328 motorola sensor device data www.motorola.com/semiconductors figure 4. boat speedometer display board lcd liquid crystal display iee part number lcd5657 or equal 26 37 36 5 6 7 34 35 8 31 32 9 10 11 29 30 12 26 27 13 14 15 24 25 16 22 23 17 18 19 20 21 1 19 18 17 16 15 14 13 11 10 9 8 7 6 5 4 3 44 43 42 41 40 39 38 37 36 35 33 32 31 30 29 28 27 nc bp 26 22 21 2 +5 r1 470 k c1 470 pf osc in v ss v cc out in data bit u1 mc145453fn data clock 25 24 1 2 3 4 clock data + gnd 5 v dd v ss c2 0.1 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3329 motorola sensor device data www.motorola.com/semiconductors table 1 lists the jumper wire selections needed for calibration and operational modes. the jumper wire junction block (j1, j2, j3) is connected to the microprocessor, pins pc0, pc1 and pc2, respectively as shown in figure 5. table 1. j1 j2 j3 out out out display speed in mph out out in 100 psi xducer installed out in out 30 psi xducer installed out in in 15 psi xducer installed in out out full scale calibrate in out in zero calibrate in in out display pressure in psi in in in display speed in mph figure 5. boat speedometer processor board + + + lm139a + + + +8 lm334z3 u7 r13 147 w d2 (approx. 470 m a) polycarbonate c8 0.47 m f r14 1.5 k 5% r12 4.7 w 5% 2n7000 q1 lm139a lm139a lm139a 33078 33078 +8 10 11 8 9 4 5 3 1/4 u6 1/4 u6 1/4 u6 v ref +5 r11 10 k 5% r10 10 k 5% r9 10 k 5% +5 13 14 2 r4 10 k 5% r8 10 k 5% +8 5 6 8 1/2 u3 7 15 2 3 4 1/2 u3 4 c14 22 pf c13 22 pf r5 316 k r7 316 k r6 10 k +5 16 8 7 6 10 9 13 12 11 u4 y0 y1 z0 z1 2 1 5 3 +8 32 41 74hc4053 6 7 1/4 u6 +12 gnd 5 6 d1 1n4004 r1 4.7 w 5% c1 0.1 c2 33 m f + mc78l05 acp u2 mc78l08 acp u1 v ref (approx. 4.5 v) c7 10 m f + c6 0.1 c4 10 m f + c3 0.1 +5 +8 r2 1.15 k r3 1.5 k c5 0.1 notes: unless otherwise noted, all resistors 1% metal film. * u5 pins 1116 (pc2pc7) are connected here for * termination purposes. 32 27 43 33 34 45 42 52 51 47 49 44 46 48 50 v ref 7 8 17 2 18 19 26 11* 10 9 1 31 3 20 21 22 25 4 24 23 r15 r16 r17 310 k 5% ic1 (pa2) pa7 pe0 ic2 (pa1) ic3 (pa0) pe1 pb0 v rh v rl pe2 pe3 pe4 pe5 pe6 pe7 xtal extal reset modb xirq irq v dd pc2 pc1 pc0 v ss pa3 moda pd0 pd1 pd2 pd5 stra (pd4) sck (pd3) mosi r19 10 meg 5% y1 8 mhz c12 22 pf +5 +5 r18 4.7 k 5% mc34064 p5 u8 j3 j2 j1 test jumpers 1 2 3 4 +5 c10 0.1 u5 mc68hc711e9fn mpxm2202gs f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3330 motorola sensor device data www.motorola.com/semiconductors the calibration of this system is as follows. refer to table 1. caution: while installing or changing the proper jumpers described by each step, power must be off. reapply power to read the display after jumpers have been installed in their proper location for each step. in each step there is a few seconds' delay after switching the power on and before an output is displayed. steps 1 through 3 must be performed prior to system being operational. calibration 1. the pressure range of the system must be established. the present software installed in this design supports 15, 30 and 100 psi sensors. using an mpxm2202gs sensor (30 psi) for example, only jumper j2 should be installed. after power is applied, the lcd should read a30.o power off the system prior to proceeding to step 2. 2. the total system offset, due to the sensor and a/d, must be established for the software routine to effectively calibrate. with power off, jumpers j1 and j3 should be installed. reapply power, and the lcd should respond with a000.o the offset value measured in this step is thus stored for use in circuit operation. power off the system prior to proceeding to step 3. 3. in this step, the system full scale span is calibrated. with power off, install jumper j1 only. now apply the full rated pressure (30 psi for mpxm2202gs) to the sensor, power on and ensure the display reads afff.o the full scale span measured in this step is thus stored for use in circuit operation. power off the system prior to step 4. operation 4. ensure power is off, and install jumpers j1, j2 and j3. the system is now ready for operation. simply apply power and pressure to the sensor, and the lcd will display the proportional speed above 5 mph, up to the limits of the sensor. references burry, michael (1989). acalibrationfree pressure sensor system,o motorola application note an1097. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3331 motorola sensor device data www.motorola.com/semiconductors note. this was compiled with a compiler courtesy of: introl corp. 9220 w. howard ave. milwaukee, wi. 53228 phone (414) 3277734. some source code changes may be necessary for compilation with other compilers. the header file io6811.h has i/o port definitions for the i/o ports particular to the mc68hc711e9. a typical entry for port a will follow. the first line establishes a base address by which all i/o facilities and counters are biased. refer to the mc68hc711e9 data for more information relative to i/o and timer addresses. #define iobias 0x1000 /* base address of the i/o for the 68hc11 */ #define porta (* (char *) (iobias + 0)) /* port a */ the startup routine need only load the stack to the top of ram, zero the microcontroller's ram and perform a bsr main (branch to subroutine amaino). this source code, header file, compiled object code, and listing files are available on: the motorola freeware line austin, tx. (512) 8913733. bill lucas 6/21/90 the code starts here */ #include /* i/o port definitions */ /* define locations in the eeprom to store calibration information */ #define eeprom (char*)0xb600 /* used by calibration functions */ #define eebase 0xb600 /* start address of the eeprom */ #define adzero (* ( long int *)( eebase + 0 )) /* auto zero value */ #define hiatod (* ( long int *)( eebase + 4 )) /* full scale measured input */ #define xdcrmax (* ( char *)( eebase + 8 )) /* full scale input of the xdcr */ union bytes { unsigned long int l; char b[4]; }; /* adzero.l for long word adzero.b[0]; for byte */ const char lcdtab[] = { 95, 6, 59, 47, 102, 109, 125, 7, 127, 111, 0 }; /* lcd pattern table 0 1 2 3 4 5 6 7 8 9 blank */ const int dectable[] = { 10000, 1000, 100, 10 }; char digit[5]; /* buffer to hold results from cvt_bin_dec function */ /* ################################################################### */ /* real time interrupt service routine */ void real_time_interrupt (void) /* hits every 4.096 ms. */ { tflg2 = 0x40; /* clear the interrupt flag */ } /* ################################################################### */ /* ################################################################### */ /* write_eeprom(0xa5,eeprom); write a5h to first byte of eeprom */ void write_eeprom(char data, char *address) { pprog = 0x16; /* singlebyte erase mode */ *address = 0xff; /* write anything */ pprog = 0x17; /* turn on programming voltage */ delay(); pprog = 0x0; /* erase complete */ /* now program the data */ pprog = 0x02; /* set eelat bit */ *address = data; /* write data */ pprog = 0x03; /* set eelat and eepgm bits */ delay(); pprog = 0; /* read mode */ /* programming complete */ } /* ################################################################### */ long int convert(char polarity) f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3332 motorola sensor device data www.motorola.com/semiconductors { unsigned int cntr; /* free running timer system counter */ unsigned int r0; /* difference between cntr and input capture 1 register */ unsigned int r1; /* difference between cntr and input capture 2 register */ unsigned int r2; /* difference between cntr and input capture 3 register */ unsigned long difference; /* the difference between the upper and lower instrument amplifier outputs */ unsigned long int pfs; /* result defined as percent of full scale relative to the reference voltage */ if (polarity == 1) /* set the hc4053 configuration */ portb &= 0xfe; /* polarity = 1 means + output of sensor */ else portb |= 0x1; /* is connected to the upper opamp */ delay(); /* this will allow the hc4053 to stabilize and the cap to discharge from the previous conversion */ tflg1=0x07; /* clear the input capture flags */ cntr=tcnt; /* get the current count */ porta &= 0x7f; /* turn the fet off */ while ((tflg1 & 0x7) < 7); /* loop until all three input capture flags are set */ r0 = tic1 cntr; /* reference voltage */ r1 = tic2 cntr; /* top side of the inst. amp */ r2 = tic3 cntr; /* lower side of the inst. amp */ porta |= 0x80; /* turn the fet on */ if (polarity == 1) difference = ( r1 + 1000 ) r2; else difference = ( r2 + 1000 ) r1; pfs = (difference * 10000) / r0; if (difference > 32767) /* this will cover up the case where the a to d computes a negative value */ pfs=0; return ( pfs ); } atod() /* computes the a/d value in terms of % full scale */ { unsigned long int x,y,z; x = convert(1); /* normal */ y = convert(0); /* reversed */ z = (x + y)>>1 ; /* 2x difference / 2 */ return(z); /* z is percent of full scale */ } integrate() /* returns the a/d value in terms of % full scale and computes offset from calibration values */ { unsigned long int j; int i; j=0; for (i=0; i<20; ++i) j +=atod(); j = (j/20) adzero; /* null out the xdcr zero input offset */ return(j); } cala2d() /* returns the average of 50 raw a/d conversions this is only used by the calibration functions */ { unsigned long int j; int i; j=0; for (i=0; i<50; ++i) { j +=atod(); } j=j/50; return(j); } /* ################################################################### */ cvt_bin_dec ( unsigned int arg ) { char i; for ( i=0; i < 6; ++i ) f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3333 motorola sensor device data www.motorola.com/semiconductors { digit[i] = 0; /* put blanks in all digit positions */ } for ( i=0; i < 4; ++i ) { if ( arg >= dectable [i] ) { digit[i] = arg /dectable[i]; arg = arg(digit[i] * dectable[i]); } } digit[i] = arg; } /* ################################################################### */ delay() { int i; for (i=0; i<1000; ++i); /* delay about 15 ms. @ 8 mhz xtal */ } /* ################################################################### */ /* setup i/o for the single slope a/d, initialize the spi port, then initialize the mc145453 for output */ init_io(void) { char i; /* setup i/o for the a/d */ pactl |= 0x80; /* make pa7 an output */ porta |= 0x80; /* turn the fet on */ portb &= 0x7f; /* setup the hc4053 in the y0/z0 connect mode */ tctl2 = 0x2a; /* capture on falling edge for timer capture 0,1,2 */ tflg1 = 0x07; /* clear any pending capture flags */ /* setup the i/o for the spi subsystem */ portd=0x2f; /* set output low before setting the direction register */ ddrd=0x38; /* ss = 1, sck = 1, mosi = 1 */ spcr=0x51; /* enable spi, make the cpu the master, e clock /4 */ /* initialize the lcd driver */ for (i=0; i<4; ++i) /* four bytes of zeros */ { write_spi(0); } write_spi (2); /* this creates a start bit and data bit 1 for the next write to the mc145453 */ } /* ################################################################### */ /* this is an attempt at the newton square root method */ sqrt(unsigned long b) { unsigned long x0,x1; if ( b < 4 ) { b=2; return (b); } else x0=4; x1=10; while (x0 != x1) { if( (x1x0) ==1 ) break; x1=x0; x0=(( (b/x0) +x0 ) >> 1 ); } b=x0; return (b); } /* ################################################################### */ f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3334 motorola sensor device data www.motorola.com/semiconductors write() { char i; digit[1]=10; if (digit[2]==0) {digit[2]=10;} if ( digit[2]==10 && digit[3]==0 ) {digit[3]=10;} for ( i=1; i<5; ++i ) { if (i==4) write_spi((lcdtab[digit[i]])+0x80); else write_spi(lcdtab[digit[i]]); } write_spi (2); /* this creates a start bit and data bit 1 for the next write to the mc145453 */ } write_spi( char a ) /* write a character to the spi port */ { spdr=a; while ( ! ( spsr & 0x80 ) ) {} /* loop until the spif = 1 */ } /* ################################################################### */ /* this function is called at powerup and will determine the operation of the system. the user must complete the system configuration prior to setting the jumper in the first or last two configurations in the table or erroneous operation is guaranteed! test/operation jumper configuration: j3 j2 j1 1 = jumper removed 1 1 1 display speed in mph 1 1 0 reserved 1 0 1 30 psi xdcr installed 1 0 0 15 psi xdcr installed 0 1 1 full scale calibrate 0 1 0 zero calibrate 0 0 1 display pressure in psi 0 0 0 display speed in mph */ setconfig() { char i; for ( i=0; i<125; ++i ) delay(); /* to let the charge pump come to life wll */ i = portc & 0x07; /* and off the unused bits */ if ( i == 7 ) display_speed(); if ( i == 6 ) setup_error(); /* nonvalid pattern output se on display*/ if ( i == 5 ) {write_eeprom(30,&xdcrmax); /* xdcr is 30 psi */ display(30); } if ( i == 4 ) {write_eeprom(15,&xdcrmax); /* xdcr is 15 psi */ display(15); } if ( i == 3 ) fullscale_calibrate(); if ( i == 2 ) zero_calibrate(); if ( i == 1 ) display_pressure(); else display_speed(); } /* ################################################################### */ display(char d) f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3335 motorola sensor device data www.motorola.com/semiconductors { if (d==30) { write_spi(0); /* blank the upper digit */ write_spi(0); /* blank the next to upper digit */ write_spi(47); /* 3 */ write_spi(95); /* 0 */ } if (d==15) { write_spi(0); /* blank the upper digit */ write_spi(0); /* blank the next to upper digit */ write_spi(6); /* 1 */ write_spi(109); /* 5 */ } write_spi(2); while(1); } /* ################################################################### */ fullscale_calibrate() { int i; long int temp; union bytes average; temp=0; average.l = cala2d(); /* get the average of 50 a/d conversions */ for ( i=0; i<4; ++i) write_eeprom(average.b[i],eeprom+i+4); write_spi(0); /* blank the upper digit */ write_spi(113); /* f */ write_spi(113); /* f */ write_spi(113); /* f */ write_spi(2); while(1); } /* ################################################################### */ zero_calibrate() { int i; long int temp; union bytes average; temp=0; average.l = cala2d(); /* get the average of 50 a/d conversions */ for ( i=0; i<4; ++i) write_eeprom(average.b[i],eeprom+i); write_spi(0); /* blank the upper digit */ write_spi(95); /* 0 */ write_spi(95); /* 0 */ write_spi(95); /* 0 */ write_spi(2); while(1); } /* ################################################################### */ /* speed=8.208(square root(%full scale*transducer full scale)) */ display_speed() { long atod_result; unsigned int j; while(1) { atod_result = integrate(); /* read the a/d */ atod_result=( (atod_result*10000) / (hiatodadzero) ) * xdcrmax; atod_result=sqrt(atod_result); atod_result=(atod_result*8208)/10000; j=atod_result; f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3336 motorola sensor device data www.motorola.com/semiconductors if (j<50) { j=0; } cvt_bin_dec ( j ); write(); } } /* ################################################################### */ /* pressure=%full scale*transducer max pressure */ display_pressure() { long atod_result; int j; while(1) { atod_result = integrate(); /* read the a/d */ atod_result=( (atod_result*1000) / (hiatodadzero) ) * xdcrmax; j=atod_result/100; cvt_bin_dec ( j ); write(); } } /* ################################################################### */ setup_error() /* write oseo on the display */ { write_spi(0); write_spi(109); /* s */ write_spi(121); /* e */ write_spi(0); write_spi(2); while(1); } /* ################################################################### */ main() { init_io(); setconfig(); /* determine how to function */ while(1); /* should never return here except after calibration */ } f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3337 motorola sensor device data www.motorola.com/semiconductors
prepared by: jeffery baum systems engineering group leader sensor products division motorola semiconductor products sector phoenix, az introduction until recently, lowcost semiconductor pressure sensors were designed to measure typical fullscale pressures only as low as 10 kpa (1.5 psi). of course, ameasureo is a relative term. ameasureo is used here to imply that an output of reasonable magnitude, signaltonoise ratio, and accuracy is produced by the sensing device. such sensor products are available in various levels of integration and package types. depending on the level of application customization required and the budget available, a sensor user may choose from a range of lowpressure sensor products such as a 10 kpa abareelemento (uncompensated) device, a 10 kpa calibrated and temperature compensated device, or a fully signalconditioned (highlevel output), calibrated, and temperature compensated integrated 10 kpa device. these options are typically available as well for higher pressures ranging up to 1000 kpa. what if the sensor user must measure fullscale pressures that are two, four, or even ten times lower than what conventional sensor technology is capable of measuring? ado such applications and customers exist?'' the answer is ayeso and ayes.o there are many potential customers that require such lowpressure sensing ability, the two application examples discussed here are: (1) heating ventilation and airconditioning (hvac) in the context of building controls and (2) waterlevel sensing in appliance applications such as clothes washing machines. for the purposes of measuring low pressures, the units of inches of water ( h 2 o) or millimeters of water (mm h 2 o) will be used. typical hvac applications have a fullscale pressure of 40 mm h 2 o and washing machines have either 300 or 600 mm h 2 o, depending on the region of the world ( note: just for reference purposes, 10 kpa 40 h 2 o 1000 mm h 2 o 1.5 psi). of course, a sensor intended for a higher pressure range than the one of interest can be used. however, the effect is that only a small portion on the device's dynamic output range is used for the actual operating range. this lowlevel output may then be paired up with a larger than ideal amplifier gain. thus, a poor signaltonoise ratio is usually the result. some sensor manufacturers have recently introduced pressure sensors designed for 4 and 5 h 2 o fullscale ranges (approx. 100125 mm h 2 o). these devices typically employ silicon with very thinly micromachined diaphragms or other sensing technologies that are significantly larger in form factor without any additional functionality. thin diaphragm devices tend to be extremely fragile and unstable. even in cases where the device is sufficiently robust for the intended operating pressure range, the sensor has very poor overpressure capability. now that the pressure range of interest has been established, the stage has been set to consider the system solution that is the enabling technology for achieving such lowpressure sensing capability. also important in presenting this lowpressure system solution are some of the other application characteristics besides the pressure range. for example, the desired pressure resolution, accuracy, available power supply voltage, and endequipment system architecture play a major role in determining the implementation of this system solution. development history for simplicity's sake, let's refer to this lowpressure sensing system solution as the asmart sensingo or asmart sensor system.o one of the key performance advantages of the smart sensor system is that the output of the actual sensing element is ratiometric (linearly proportional) to the excitation voltage applied to the sensing element. since most semiconductor pressure sensors are characterized with a constant voltage power supply, current excitation will not be discussed. although a sensor's operation is specified at a given power supply voltage, there is some maximum supply that can be applied, beyond which power dissipation and selfheating produce significant output errors or exceed the package's thermal handling capability. this means that the strategy of increasing the sensor's excitation to improve the sensor's sensitivity (increase signal output for a given applied pressure) can be done in a dc fashion only up to some maximum supply voltage. for motorola pressure sensors, this limit allows only about a 50% to 60% increase in sensitivity, depending on the specific device family. about five years ago, some of my colleagues were working on pulsing the sensor supply voltage with a conventional voltage and very low dutycycle, samplingandholding the resulting output, and then filtering the output to produce a dc sensor output with very lowpower consumption. this was the impetus to consider pulsing a sensor at a much higher than recommended voltage and a low dutycycle (10% or less) for the purpose of increased sensitivity. it is true that some of the sensor's parasitic drawbacks, like its zeropressure offset voltage and temperature coefficient of offset, are increased as well, but some of the sensor's negative characteristics are lessened. in addition, other sources of error and noise in the system are not subjected to the higher amplifier gain that would be required if operating the sensor at a conventional supply voltage. semiconductor application note f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3338 motorola sensor device data www.motorola.com/semiconductors the motorola mpx2010 (see table 1) is a calibrated and temperature compensated, 10 kpa (fullscale), pressure sensor device. the data sheet specifies a fullscale output of 25 mv at a 10 v supply voltage, for an applied pressure of 10 kpa. this same device can be pulsed at 40 v at a 10% dutycycle and produce either 100 mv for the same 10 kpa pressure or 25 mv for only 2.5 kpa of pressure. this technique allows a fourfold increase in the signal level for the rated fullscale pressure of 10 kpa or the ability to maintain the same signal level for a pressure that is four times lower (2.5 kpa). although the idea is relatively simple, the key to providing a lowcost smart sensing solution is in both the hardware and software implementation of this system. in the case of the micropower application, having a astandaloneo analog sensing solution was a key criteria. as such, this design used micropower opamps, analog cmos switches, gated timers (one to control pulsed sensor excitation and one to control sampleandhold function), and capacitive sampleandhold circuitry. the effect was a very lowcurrent drain, micropower sensor solution. since lowpower, rather than lowpressure, was the driving design goal, errors induced by power supply variation, temperature drift, and devicetodevice tolerances were not critical. not that these issues are not important for all applications, but for lowpressure sensing, even small temperature drifts, device parameter tolerances, and power supply variations cause significant errors as a percentage of the sensor output signal. it should be apparent that the agatedtimer pulsing/sampleandholdo system architecture can be equally well employed to pulse at higher voltages for increased sensitivity. however, a lowcost mcu can also accomplish the functions of providing a control pulse to a switching circuit (for the pulsed sensor excitation) and affecting a synchronized sampleandhold feature via software control of an onchip a/d converter. in addition, the mcu has the capability to implement other asmarto features that can lend the additional required accuracy and functionality desired for many lowpressure sensing applications. the system design intended for lowpressure applications, as well as the performanceenhancing features of pulsed excitation for increased sensitivity, signal averaging, software calibration, and software power supply rejection are presented. the added functionality of intelligent communications capability and serial digital output flexibility are also discussed. of course, these features lead to increased performance at conventional, or even highpressure ranges. nonetheless, these features have been developed in the context of lowpressure sensing where the performance benefits are a requisite of the application. also, driving acceptance of this system technology is a much easier task when coupled to providing a sensing capability and level of functionality that is otherwise not available in the industry today. who would have suspected that a viable smart sensing technology would have resulted from the pursuit of addressing the lowpressure sensing market? significant pieces of this system solution are protected intellectual property. motorola holds several key patents on using pulsed excitation for semiconductor sensors and has filed several others regarding other portions and future enhancements to this technology. table 1. mpx2010 operating characteristics (supply voltage = 10 vdc, t a = 25 c unless otherwise noted) characteristic min typ max unit pressure range 0 e 10 kpa supply voltage e 10 16 vdc supply current e 6.0 e madc full scale span (fss) 24 25 26 mv zeropressure offset 1.0 e 1.0 mv sensitivity e 2.5 e mv/kpa linearity 1.0 e 1.0 %v fss pressure hysteresis (0 to 10 kpa) e 0.1 e %v fss temperature hysteresis ( 40 c to +125 c) e 0.5 e %v fss temperature effect on full scale span 1.0 e 1.0 %v fss temperature effect on offset (0 c to 85 c) 1.0 e 1.0 mv input impedance 1300 e 2550 w output impedance 1400 e 3000 w response time (10% to 90%) e 1.0 e ms temperature error band 0 e 85 c offset stability e 0.5 e %v fss f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3339 motorola sensor device data www.motorola.com/semiconductors system design as mentioned in the introduction, the lowest pressure devices in the motorola portfolio are rated at a fullscale pressure of 10 kpa (40 of h 2 o). the calibrated and temperature compensated, 10 kpa device (mpx2010) is specified to operate at a 10 vdc supply voltage and produce 25 mv (nominal) at the fullscale pressure of 10 kpa. this translates to a 0.25 mv/(v*kpa) pressure sensitivity. additionally, the absolute maximum supply voltage specified is 16 vdc. thus, the maximum fullscale output signal that can be achieved without exceeding the maximum supply voltage rating is 40 mv, or 60% greater than the output at the 10 vdc specification. so, a 60% increase can be achieved in the output signal of the sensor for the 010 kpa pressure range, or the same signal level of 25 mv can be preserved over a proportionally lower applied pressure range (i.e., 06.25 kpa). the point here is that increasing the dc supply excitation only produces limited improvement in the output signal level. much greater gains in output signal level (sensor span) can be obtained, if it is possible to operate the sensor at significantly higher voltages. since the thermal/power dissipation limitation imposed by the maximum dc supply voltage can be avoided by using a pulsed excitation at a low dutycycle (ontime) and reasonable period, and second order junction effects do not occur until much higher voltages, the sensor output can be greatly increased by operating at a much higher ac voltage than permitted by the dc counterpart of this same higher voltage. as an example, industrial applications like hvac have 24 v commonly available, and we want to accurately measure pressures below 10 h 2 o. to achieve a 12% of fullscale accuracy (based on temperature drift errors, system noise, device tolerance, power supply variation/rejection, etc.), 912 mv is the typical minimum fullscale span that is the desired target for the pressure range of interest. for the mpx2010 pulsed at 24 v, we obtain 15 mv of output for an applied pressure of 10 h 2 o (2.5 kpa). this same sensor device will only produce 6.25 mv at its normally specified supply of 10 v and 2.5 kpa, thus not meeting the signaltonoise ratio criteria for a 12% accuracy performance. this smart sensing solution is intended to sense fullscale pressures below 10 h 2 o with 1% of fullscale pressure resolution and better than 2% of fullscale accuracy. the following subsystems comprise the hardware portion of this solution (see figure 1): figure 1. smart sensing block diagram pressure sensor signal conditioning switching circuitry low voltage inhibit 8bit microcontroller 5 v 5% regulator power supply rejection circuitry v pp d out d in sclk cs v cc gnd f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3340 motorola sensor device data www.motorola.com/semiconductors ? highside switch pulsing circuitry ? signalconditioning amplifier interface with resistors to ad- just the sensor's amplified, fullscale span and zeropres- sure offset ? onchip resources of a complete 8bit microcontroller (mcu) ? mcu oscillator circuitry (4 mhz) ? 5 v 5% linear voltage regulator ? lowvoltage inhibit (lvi) supervisory voltage monitoring cir- cuit ? resistor divider connected to the sensor's power supply bias to sense the excitation voltage across the sensor these subsystems are explained as follows to provide an understanding of the system design and its intelligent features (refer to figure 2). pulsing circuitry as previously mentioned, the sensor's output is ratiometric to the excitation voltage across the sensing element; the sensor's sensitivity increases with increasing supply voltage. thus, to detect low pressures and minute changes in pressure, it is desirable to operate the sensor at the highest possible excitation voltage. the maximum supply voltage at which the sensor can reliably operate is determined by one or both of the following two limitations: (1) maximum allowable sensor die temperature, (2) maximum supply voltage available in the sensing application/system. in terms of thermal/power dissipation, the maximum voltage that can be supplied to the sensor on a continuous basis is relatively low compared to that which can be pulsed on the sensor at a low dutycycle. the average power that is dissipated in the sensor is the square of the average sensor excitation voltage divided by the input resistance of the sensor. when the sensor's supply bias is operated in a pulsed fashion, the average excitation voltage is simply the product of the dc supply voltage used and the percent dutycycle that the dc voltage is aon.o the pulsing circuitry is a highside switch (two smallsignal switching transistors with associated bias resistors) that is controlled via the output compare (tcmp) pin of the mcu. the output compare timer function of the mcu provides a logiclevel pulse waveform to the switch that has a 2ms period and a 200 m s ontime ( note: this is userprogrammable). figure 2. system schematic signal conditioning even with pulsing at a relatively high supply voltage, the pressure sensing element still has a fullscale output that is only on the order of tens of millivolts. to input this signal to the a/d converter of the mcu, the sensing element output must be amplified to allow adequate digital resolution. a basic twooperational amplifier signalconditioning circuit is used to provide the following desired characteristics of an instrumentation amplifier interface: ? high input impedance ? low output impedance ? differential to singleended conversion of the pressure sen- sor signal ? moderate gain capability both the nominal gain and offset reference pedestal of this interface circuit can be adjusted to fit a given distribution of sensor devices. varying the gain and offset reference pedestal f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3341 motorola sensor device data www.motorola.com/semiconductors is desirable since pressure sensors' fullscale span and zeropressure offset voltages will vary somewhat from lot to lot and unit to unit. during software calibration, each sensor device's specific offset and fullscale output characteristics will be stored. nonetheless, a variable gain amplifier circuit is desirable to coarsely tune the sensor's fullscale span, and a positive or negative dc level shift (offset pedestal adjustment) of the pressure sensor signal is needed to translate the pressure sensor's signalconditioned output span to a specific level (e.g., within the high and low reference voltages of the a/d converter). microcontroller the microcontroller performs all of the necessary tasks to give the smart sensor system the specified performance and intelligent features. the following describes its responsibilities: ? creates the control signal to pulse the sensor. ? samples the pressure sensor's output. ? signal averages a programmable number of samples for noise reduction. ? samples a scaleddown version of the pressure sensor supply voltage. monitoring the power supply voltage allows the microcontroller to reject sensor output changes result- ing from power supply variations. ? uses serial communications interface (spi) to receive com- mands from and to send sensor information to a master mcu. resistor divider for rejection of supply voltage variation since the pressure sensor's output voltage is ratiometric to its supply voltage, any variation in supply voltage will result in variation of the pressure sensor's output voltage. by attenuating the supply voltage (since the supply voltage may exceed the 5 v range of the a/d) with a resistor divider, this scaled voltage can be sampled by the microcontroller's a/d converter. by sampling the scaled supply voltage, the microcontroller can compensate for any variances in the pressure sensor's output voltage that are due to supply variations. this technique allows correct pressure determination even when the pressure sensor is powered with an unregulated supply. 5 v regulator a 5 v 5% voltage regulator is required for the following functions: ? to provide a stable 5 v for the high voltage reference (vrh) of the microcontroller's a/d converter. a stable voltage ref- erence is crucial for sampling any analog voltage signals. ? to provide a stable 5 v for the resistor divider that is used to level shift the amplified zeropressure offset voltage. low voltage inhibit (lvi) circuitry low voltage inhibit circuitry is required to ensure proper poweronreset (por) of the microcontroller and to put the mcu in a known state when the supply voltage is decreased below the mcu supply voltage threshold. software description the smart sensor system's eprom resident code provides the control pulse for the sensor's excitation voltage and performs calibration with respect to a wide range of excitation voltages (20 ~ 28 v typically for hvac). pressure measurement averaging is also incorporated to reduce both signal error and noise. in addition, the availability of a serial communications interface allows a variety of software commands to be sent to the smart sensor system. the following brief outline provides a more detailed description about the software features included in the smart sensor system. software calibration and power supply rejection only six 8bit words of information are stored both to calibrate the smart sensor system for a given sensor device and to store the relationship between sensor output and power supply voltage. this information is used to reduce errors due to devicetodevice variations and to reject variations in power supply voltage that can introduce error into the pressure measurement. the sensor's amplified output at the zeropressure offset and fullscale pressure are stored at each of two different supply voltages. in addition, the scaled and digitized representation of the applied supply voltages is stored. compensating for power supply variation in software allows higher performance with lower tolerance, or even unregulated, supply voltages. for hvac applications, where a 24vac line voltage will be simply rectified and filtered to provide a crude 24vdc supply, this approach has major performance benefits. the impact on applications where a regulated supply is available is that a lowercost regulator or dctodc converter can be used without compromising system accuracy significantly. a/d sample averaging noise inherent to the 8bit a/d successive approximation conversion method used by the smart sensor accounts for 1bit resolution. signal noise, which exhibits a measured peaktopeak range larger in magnitude than 1 bit of a/d resolution, can be minimized by a sample averaging technique. the current technique uses 16 a/d converted pressure samples, sums the result, and divides by 16 (the number of samples) to get the average: avg = ; where n = 16 (1) ( a n ) n n 1 assuming a gaussian distribution of noise, this averaging technique improves the signaltonoise ratio (snr). smart sensor unit id and software revision level this solution may be implemented as a single sensing system using a nondedicated mcu to provide the sensing function and smart features or as a slaved smart sensor (with dedicated sensing mcu) that communicates over a serial bus to a master controller or microprocessor (host). part identification and software revision level can also be read on request from the master mcu. this information is utilized by the master mcu to determine what the fullscale pressure range of a given smart sensor unit is. this allows for multiple sensor units with different pressure ranges to be controlled and sensed from a single master mcu. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3342 motorola sensor device data www.motorola.com/semiconductors table 2. software command codes function (command codes) command from host data from smart sensor request pressure $01 $00$ff dynamic zero $02 e undo dynamic zero $03 e pressure range $04 tbd communication the serial peripheral interface (spi) is used to communicate to a master/host mcu. the master mcu initiates all i/o control and sends commands to the slave regarding data requests, calibration, etc. the command codes are parsed at the slave in a lookup table, at which time the corresponding request is serviced via subroutine. table 2 lists the master/slave commands. request pressure returns the percent of fullscale pressure applied to the sensor in the form of $00 (0) through $ff (255) and is equivalent to: pressure range (from 0 to 255), where x fs = measured pressure (2) (0 255) 255 (this calculation is performed by the master mcu.) dynamic zero assigns current input pressure as the offset value, in order to use a nonzero pressure as the offset reference. undo dynamic zero resets offset to the original stored offset (see dynamic zero). pressure range returns a value representing the sensor's fullscale pressure range. figure 3. spi timing diagram f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3343 motorola sensor device data www.motorola.com/semiconductors software examples the following example listings show how a user may communicate with the smart sensor via a master mcu. the software example shown assumes that the master mcu is an mc68hc11. any mcu with the proper i/o functionality will operate similarly with the smart sensor system. when using parallel i/o instead of an spi port to interface the smart sensor, the user must abit bango the clock and data out of the parallel i/o, so as to simulate the spi port. as long as the timing relationships of data and clock follow those of figure 3 (see also table 3), the smart sensor will function properly when interfaced to a processor with a parallel type interface. in the following two code examples, the sensor unit is interfaced to the master mcu via the spi port, and the sensor's cs input is connected to the hc11's port d pin 5. this example is coded in `c' for the mc68hc11: /* first initialize the i/o (include a header file to include i/o definitions) */ void init_io(void) { portd = 0x29; /* ss* pd5 = 1, pd3 = 1, pd0 = 1 */ ddrd = 0x3b; /* ss* pd5 = 1, pd3 = 1, pd1 = 1, pd0 = 1 */ spcr = 0x5e; /* enable the spi, make mcu the mastr, sck = e clk /4 */ /* i/o initialization is complete */ } /* we need a function to write to and read from the spi */ write_spi(char data) { spdr = data; /* write the data to the spi data port */ while( ! (spsr & 0x80 )); /* wait until data has shifted out of and back into the spi */ return(spdr): /* retrieve the results of the last command to the sensor and return */ } /* now we need to call the above */ void main(void) { char rtn_data; /* rtn_data is the returned data from the sensor */ init_io(); while(1) /* just loop forever */ rtn_data = write_spi(0x01); /* 0x01 is the command to the sensor that requests pressure. the value in rtn_data will be in the range of 0..0xff = 0..100% full scale pressure the second time through the loop. the initial time through the loop, the data returned is indeterminate */ } the next example is coded in assembly for the mc68hc11: * port offsets into the i/o map ports equ $1000 assume the i/o starts at $1000 portd equ $8 ddrd equ $9 spcr equ $8 spsr equ $29 spdr equ $2a org $e000 * first initialize the i/o initio ldx #ports base address of the i/o ldaa #$29 staa portd,x ss* pd5 = 1, pd3 = 1, pd0 = 1 ldaa #$3b staa ddrd,x ss* pd5 = 1, pd3 = 1, pd1 = 1, pd0 = 1 ldaa #$5e staa spcr,x enable the spi, make mcu the mastr, * sck = e clk /4 rts i/o initialization is complete f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3344 motorola sensor device data www.motorola.com/semiconductors *we need a subroutine to write to and read from the spi *to call this routine load accumulator a with the command data *and jsr writspi. when the routine returns, accumulator a *contains the data returned from the sensor writspi ldx #ports base address of the i/o staa spdr,x send the command to the sensor wrloop brclr 7,spsr,wrloop loop until the data has shifted out of and back into the spi ldaa spdr,x retrieve the results of the last command * to the sensor rts * now we need to call the above */ start jsr initio setup the i/o loop ldaa #$1 1 is the command to the sensor that * requests pressure jsr writspi send the command to the sensor. * ... the value returned in accumulator a * will be in the range 0..0xff = 0..100% * full scale pressure the second time * through the loop. the initial time * through the loop, the data returned is indeterminate data from the sensor bra loop table 3. spi timing characteristics characteristic symbol min max unit frequency of operation f op dc 525 khz cycle time t sclk e 1920 ns clock (sclk) low time t sclkl 932 e ns d out data valid time t v e 200 ns d in setup time t s 100 e ns d in hold time t h 100 e ns onbus delay time t d1 1 e ms offbus delay time t d2 e 50 m s chip select period t d3 tbd e ms serial data output format the serial data output is an 8bit number of value 0255. this number represents the current applied pressure as a percentage of the fullscale pressure rating of the smart sensor. the master mcu can simply consider an output of a0o to be zero pressure and a255o to be fullscale pressure. to convert this number to engineering units, such as inches of water ( h 2 o), the master mcu must multiply the smart sensor output (0255) by the fullscale pressure of the smart sensor in h 2 o and then divide (normalize) by 255. see equation 2. the master mcu can either use an absolute number for the fullscale pressure of the smart sensor (as indicated previously) or can query each smart sensor that is connected to the serial bus for its rated pressure range. the latter technique allows multiple smart sensors of various fullscale pressure ranges to be communicating with a single master mcu, without the need for an absolute addressing scheme that contains fullscale pressure information for each sensor. conclusion a smart sensing system that achieves high performance for lowpressure applications has been presented here. the key performance advantage of the smart sensor system is that it takes advantage of the fact that the output of the actual sensing element is ratiometric (linearly proportional) to the excitation voltage applied to the sensing element. a sensor device is pulsed at a much higher than normally specified voltage and a low dutycycle for the purpose of increased sensitivity. although some of the sensor's parasitic drawbacks are increased in magnitude, some of the sensor's negative characteristics are lessened, and other sources of error and noise in the system are reduced. the net effect is that a better signaltonoise ratio is obtained. this, combined with several other performanceenhancing smart features, provides better pressure resolution and accuracy than inherent in the sensor device alone. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3345 motorola sensor device data www.motorola.com/semiconductors besides the sensor excitation pulsing and output sampling functions, a lowcost mcu provides the performance enhancing features of signal averaging, software calibration, and software power supply rejection. the addedfunctionality of intelligent communications capability, serial digital output flexibility, and local control and decisionmaking capability are also at the user's disposal. the development history, system design, software functions, example communications routines, and serial output format have been detailed to provide the reader with an understanding of how lowpressure capability can be greatly enhanced via a smart sensor system approach. acknowledgments i wish to acknowledge my colleagues bill lucas and warren schultz for their outstanding efforts and major contributions to the pursuit of lowpressure sensing technology. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3346 motorola sensor device data www.motorola.com/semiconductors
! prepared by: eric jacobsen and jeff baum sensor systems engineering group motorola sensor products division phoenix, az introduction when designing a circuit for a sensor system, it is desirable to use fixedvalue components in the design. this makes the system easier and cheaper to produce in high volume. the alternatives to using fixedvalue circuitry are very expensive and usually impractical: lasertrimming resistances, manually calibrating potentiometers, or measuring and selecting specific component values are all very laborintensive processes. however, every sensor has devicetodevice variations in offset output voltage, fullscale output voltage, dynamic output voltage range (difference between the fullscale output voltage and zeroscale output voltage which is commonly referred to as the span), etc. moreover, these same parameters also vary with temperature e e.g., temperature coefficient of offset (tcv off ) and temperature coefficient of fullscale span (tcv fss ). to further complicate this situation, the fixedvalue circuit in which a sensor is applied also has variation e e.g., the voltage or current regulator and resistors all have a specified tolerance. since today's unamplified solidstate sensors typically have an output voltage on the order of tens of millivolts (motorola's basic 10 kpa pressure sensor, mpx10, has a typical fullscale span of 58 mv, when powered with a 5 v supply), a major part of the fixedvalue circuitry is a gain stage that amplifies the signal to a level that is large enough for additional processing. typically, this additional processing is digitization of the amplified analog sensor signal by a microcontroller's a/d converter. to obtain the best signal resolution with an a/d, the sensor's amplified dynamic output voltage range should fill as much of the a/d window (difference between the a/d's high and low reference voltages) as possible without extending beyond the high and low reference voltages (i.e., the zeropressure offset voltage must be greater than or equal to the low reference voltage, and the fullscale output voltage must be less than or equal to the high reference voltage). in any case, the devicetodevice, temperature, and circuit variations create a design dilemma: with a fixedvalue amplifier circuit, the gain as well as any dc level shift incorporated in the amplifier design are fixed. if the variation of any of the aforementioned sensor parameters is too large, the amplified sensor output may saturate the amplifier near either its high or low supply rail or may extend beyond either the high or low reference voltages of the a/d converter. in either case, error (nonlinearity) results in the system. to avoid this scenario, the solution is to design a fixedvalue circuit that optimizes performance (signal resolution) while taking into account all possible types of variation that may cause the sensor output to vary. in other words, the goal of this fixedvalue sensor system is to attain the best performance possible while ensuring through design, regardless of any system variation, that the sensor's amplified output will always be within the saturation levels of the amplifier and the high and low reference voltages of an a/d converter. the implication of ensuring that the sensor's amplified output is always unsaturated and within the high and low reference voltages of the a/d is that an accurate software calibration of the sensor's output is possible. by sampling the sensor's output voltage at a couple of points at room temperature (zero and fullscale output, for example), all the room temperature devicetodevice and circuit variations are nullified. obviously, temperature variations will create error in the system (sensor's output voltage will drift with changing temperature), but, by design, the sensor's output voltage will remain within the a/d's valid range. this paper discusses a methodology that optimizes a sensor system's performance while considering devicetodevice, temperature, and circuit variations that can create variation in the amplified sensor output. the methodology starts with a desired performance and some established parameters and then considers each type of variation in a worst case analysis to determine if the desired performance is attainable. while this paper discusses this methodology for pressure sensors and a specific amplifier topology, the methodology is applicable to lowlevel, differentialvoltage output sensors and amplifier circuits in general. two specific examples are presented that apply this methodology. the first example uses motorola's mpx10 pressure sensor, and the second example uses motorola's mpx2010 pressure sensor. both sensors have a fullscale rated pressure of 10 kpa; the difference between the devices is the mpx2010 has onchip calibration and temperature compensation circuitry to calibrate and temperature compensate the zeropressure offset voltage and span. the comparison of these two devices will emphasize how dramatically devicetodevice and temperature variations, if not compensated, can affect a system's overall performance.
semiconductor application note f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3347 motorola sensor device data www.motorola.com/semiconductors the example circuit referring to figure 1, both pressure sensors are interfaced to the same amplifier circuit topology. in tables 1 and 2, the relevant characteristics for the mpx10 and mpx2010 show the devicetodevice and temperature variations. additionally, the tolerances on the voltage regulator and the resistors that establish the gain and dc voltage level shift (v ref ) are considered in the methodology. the voltage regulator's devicetodevice tolerance is 5%, and each resistor's tolerance is 1%. + + v in 5 v reg. ( 5%) in out gnd v s r ref1 s s+ x1 mpx10 or mpx2010 r1 r2 r3 r4 u1 u1 lm33272 v o to a/d r ref2 v ref figure 1. mpx10/mpx2010 circuit schematic table 1. mpx10 variation characteristics characteristic (v s = 5.0 v) symbol min typ max unit pressure range p op 0 e 10 kpa fullscale span v fss 33 58 83 mv zero pressure offset v off 0 33 58 mv temperature coefficient of fullscale span (see note 1) tcv fss 0.22 0.19 0.16 %/ c temperature coefficient of offset (see note 2) tcv off e 15 e m v/ c note 1: slope of endpoint straight line fit to fullscale span at 40 c and +125 c relative to 25 c note 2: slope of endpoint straight line fit to zero pressure offset at 40 c and +125 c relative to 25 c table 2. mpx2010 variation characteristics characteristic (v s = 5.0 v) symbol min typ max unit pressure range p op 0 e 10 kpa fullscale span v fss 12 12.5 13 mv zero pressure offset v off 0.5 e 0.5 mv temperature effect on fullscale span (see note 1) tcv fss 1.0 e 1.0 %fss temperature effect on offset (see note 2) tcv off 0.5 e 0.5 mv note 1: maximum change in fullscale span at 0 c and 85 c relative to 25 c note 2: maximum change in offset at 0 c and 85 c relative to 25 c the amplifier topology used is a twooperational amplifier gain stage that has all the desirable characteristics of a differentialsignal instrumentation amplifier: ? high input impedance ? low output impedance ? differential to singleended conversion of the input signal ? high gain capability ? dc level shifting capability for good common mode rejection, the following resistor ratios are used: r 4 r 3 r 1 r 2 with this simplification, the transfer function of the amplifier is v o ( r 4 r 3 1 ) (s s ) v ref f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3348 motorola sensor device data www.motorola.com/semiconductors where the gain is ( r 4 r 3 1 ) , the pressure sensor's differential output voltage is the quantity (s + s ), and the positive dc voltage level shift, created by the voltage divider comprised of r ref1 and r ref2 , is v ref . in addition to using the above resistor ratios to preserve the common mode rejection, the effective resistance of the parallel combination of r ref1 and r ref2 should be a low impedance to ground relative to the resistance of r 1 . resolution and factors that affect it performance of a pressure sensor system is directly related to its resolution. resolution is the smallest increment of pressure that the system can resolve e e.g., a system that measures pressure up to 10 kpa (fullscale) with a resolution of 1% of fullscale can resolve pressure increments of 0.1 kpa. similarly, the resolution (smallest increment of voltage) of an 8bit a/d converter with a 5 v window (a high reference voltage of 5 v and a low reference voltage of 0 v) is 5v 255 (8 bits) 19.6 mv many pressure sensor systems interface an a/d converter. if the above system example requires 1% resolution when interfaced to an a/d, the pressure sensor signal's span must be at least 19.6 mv 1% 1.96 v if the system resolution required is 0.5%, the pressure sensor signal's span must be at least 19.6 mv 0.5% 3.92 v from these examples, the greater the resolution required, the greater the sensor's amplified span must be to meet the resolution requirement. since a pressure sensor's span before amplification is only on the order of tens of millivolts, the amplifier must be designed to provide the minimum span that gives the desired resolution. if the amplifier has a fixed gain, any devicetodevice variation in the sensor's unamplified span will result in variation of the amplified span. if, for example, the sensor's span variation results in an amplified span that is smaller than required, the resolution of the system will not be as high as desired. alternately, if the sensor's span variation results in an amplified span that is larger than required, the resolution will be better than desired, but the amplified span may also either saturate the amplifier near its supply rails or extend outside the high and low reference voltages of the a/d. voltages above the high reference will be digitally converted as 255 decimal (for 8bit a/d), and voltages below the low reference will be converted as 0. this creates a nonlinearity in the analogtodigital conversion and in the overall system transfer function. as presented above, the variation of the sensor's span creates a dilemma: how does one design a fixedgain amplifier that gives the desired resolution, does not violate the limits of the linear output ranges of the opamps and a/d converter, and also accommodates the complete distribution of possible sensor spans? the same question is presented to the additional sources of variation: devicetodevice variation in the zeropressure offset voltage and temperature effects on both the sensor's span and zeropressure offset voltage. also any component tolerances for the voltage regulator and resistors must be considered. designing the system when only one source of variation is involved is not difficult; however, when all of these variations are interacting, the solution becomes complicated. the rest of this paper describes a design methodology that considers all of the above variations and their interactions. worst case limits will be used in designing the fixedvalue system. resolution vs. headroom as stated previously, the amplified span of the sensor must afito within the high and low references of an a/d to avoid any nonlinearity errors. and the span must also be large enough to provide the resolution required for the application. any part of the a/d's awindowo that is not used for the sensor's dynamic signal range is called headroom. headroom may be thought of as a cushion between the high and low reference voltages and the sensor's dynamic output range. this acushiono is used to allow the sensor's dynamic range to move and/or vary within the a/d's window. a general description is shown in figure 2. the total amount of sensor output signal variation (due to temperature effects, devicetodevice variation, and interface circuit component tolerances) cannot exceed the headroom that is available for the requisite amount of system resolution. a larger sensor span (more bits used for signal resolution) means a smaller amount of headroom available to accommodate sensor parameter and interface circuit variations. this makes the tradeoff between resolution and variation obvious. the more variation in the system, the more headroom that is required to allow for the variation and, consequently, less of the a/d window is available for the sensor's atruesignalo span. less span results in poorer resolution (less bits used for resolving sensor output signal). a/d high reference or high sat. level of amplifier fullscale output voltage zero pressure offset voltage a/d low reference or low sat. level of amplifier headroom headroom a/d's or amplifier's dynamic range sensor's fullscale voltage span figure 2. sensor's fullscale span vs. headroom f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3349 motorola sensor device data www.motorola.com/semiconductors the methodology to optimize performance the methodology starts with defining all the known parameters. the parameters with an asterisk (*) are specified at 25 c. ? resolution ? maxfss (*) ? minfss (*) ? tcv fss (*) ? maxsensoff (*) ? minsensoff (*) ? tcv off ? v lo ? v hi ? v ref ? v tol ? mintemp ? maxtemp = desired system resolution = maximum fullscale voltage span of = the pressure sensor = minimum fullscale voltage span of = the pressure sensor = the maximum temperature coefficient = of the sensor's fullscale voltage span = the maximum zero pressure offset = voltage of the pressure sensor = the minimum zero pressure offset = voltage of the pressure sensor = the sensor's maximum temperature = coefficient of offset voltage = the low saturation level of the amplifier = or low reference voltage of an a/d = (whichever is most limiting case) = the high saturation level of the = amplifier or the high reference voltage = of an a/d (whichever is most limiting = case) = the reference voltage for positive dc = voltage level shifting = the voltage regulator tolerance = the application's minimum operating = temperature = the application's maximum operating = temperature these parameters are either chosen for the application (e.g., system resolution) or can be determined from the sensor's data sheet. tables 1 and 2 provide the necessary information for the design examples presented here. note: the data in tables 1 and 2 are scaled for a 5 v supply voltage, whereas the mpx10 and mpx2010 data sheets are specified at a 3 v and 10 v supply voltage, respectively. the following steps outline the methodology that will be applied to the mpx10 in the first design example and then applied to the mpx2010 in the second design example. 1. determine/choose the required resolution for the system. 2. calculate the number of steps required for the chosen resolution. the resolution determines the number of steps into which the pressure signal needs to be broken [see figure 3 where an 8bit a/d (255 steps of resolution) is assumed]. a conservative approach to determining this number of steps is to assume that with an a/d, the digital quantization of the pressure signal can be plus or minus one step. therefore, assume that it takes twice the number of steps previously determined to resolve a given minimum incremental pressure. the number of steps for the chosen resolution is number of steps 2 100 resolution the scaling factor of 100 in the numerator converts the resolution from a percentage to a decimal fraction. a/d high reference a/d low reference step 255 step 0 step 127 a/d's dynamic range figure 3. the 255 digital steps of an 8bit a/d 3. calculate the minimum amplified sensor span (defined as the minimum required span e see figure 4) required for this resolution requirement. using an 8bit a/d with a 5 v window where one step equals 19.6 mv (for the nominal regulator voltage), the minimum amplified sensor span is minimum required span (number of steps) (19.6 mv) a/d high reference a/d low reference zero pressure offset voltage fullscale output voltage minimum required span maximum span a/d's dynamic range figure 4. the minimum required span for the required resolution and the maximum span due to sensor span variations 4. calculate the amplifier's gain. the gain must be large enough to achieve, over the entire distribution of sensor spans, the minimum required span. therefore, this gain is calculated using the smallest pressure sensor voltage span, minfss. by using the worst case smallest pres- sure sensor voltage span to calculate the gain, the minimum required span (the minimum span that will achieve the resolution requirement) is guaranteed for the entire distribution of sensor spans. the worst case minimum fullscale sensor span will occur at the hottest temperature, maxtemp, in the application (not exceeding the operating temperature of the sensor), since the span decreases with increasing temperature (tcv fss is negative). gain minimum required span [minfss] [1 tcv fss (maxtemp25)] the term [1 + tcv fss ? (maxtemp 25)] is the temperature effect on the span. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3350 motorola sensor device data www.motorola.com/semiconductors summarizing (through step 4), the calculations are based on a minimum desired resolution. the resolution requirement determines the number of steps or apieceso into which the signal must be broken. this number of steps or apieceso multiplied by the number of millivolts per step equals a minimum voltage range which is defined as the minimum required span. finally to ensure that this minimum required span is achieved over the entire distribution of sensor spans, the gain is calculated using the worst case smallest sensor span. note: the gain also will have variation due to resistor tolerances in the amplifier circuit. to ensure that the system variation due to resistor tolerances is negligible when compared to other sources of variation, the system should be designed using resistors with tolerances of 1% or better. 5. calculate the worst case maximum span. the maximum span is the largest possible span and is calculated using the maximum fullscale sensor voltage span, maxfss, and the gain. the worst case maximum fullscale sensor span occurs at the coldest temperature, mintemp. after calculating the maximum span, the remaining dynamic range within the a/d's window or saturation levels of the amplifier is the smallest number of abitso (most limiting case) available for headroom. maximum span = [gain] ? [maxfss] ? [1 + tcv fss ? (mintemp 25)] the term [1 + tcv fss ? (mintemp 25)] is the temperature effect on the span. the maximum span calculated from the above equation is depicted in figure 4. 6. calculate the calculated headroom. the calculated headroom is a subset of the general term aheadroomo because it reserves abitso in the a/d's dynamic range only for the sources of variation from the sensor's zeropres- sure offset voltage. headroom, in general, is reserved for all sources of variation: system components, resistor tolerances (if significant), and the sensor. however, the largest part of the aheadroomo must be reserved for the devicetodevice variations and temperature effects on the sensor's zeropressure offset voltage. therefore, the sources of variation from the other system components are subtracted immediately from the headroom so that the focus can be on the sensorrelated variations (refer to figure 5 and the following equation for the calculated headroom). for these design examples, the supply is a single, regulated 5 v 5% supply (the regulator's tolerance is referred to as v tol ). an assumption for a typical railtorail opamp's saturation levels (referred to as v lo and v hi ) is 0.2 v above the low supply rail (ground) and 0.2 v below the high supply rail (5 v). additionally, the worst case (smallest) supply voltage is 5 v 5% or 4.75 v. calculated headroom 5 (1 v tol 100 )2 v lo maximum span the preceding equation assumes that the difference between v hi and the high supply rail (or high reference of an a/d) is equal to the difference between v lo and the low supply rail (or low reference of an a/d); thus the term (2 ? v lo ). v s 's nominal value (not including v tol ) v s (including v tol ) and a/d high reference high sat. level of amplifier fullscale output voltage zero pressure offset voltage low sat. level of amplifier ground and a/d low reference maximum span calculated headroom amplifier's dynamic range figure 5. from ground to v s , a section of voltage is reserved for each source of variation step 6 is considered a pivotal step because it transitions the methodology's calculations from the performance require- ments to the headroom requirements. up to step 6, the methodology considered only the span of the sensor to guarantee a minimum resolution despite devicetodevice variation, component tolerances, and temperature effects. upon calculating the calculated headroom, the remaining steps of the methodology that are detailed below consider the offset variations (due to devicetodevice and temperature). these offset variations are added together to comprise what is defined as the required headroom which is the required number of abitso in the a/d's dynamic range needed to accommodate the offset variations. this required headroom is then compared to the calculated headroom (from the preceding calculation) to determine if the calculated head- room is sufficient to allow for the offset variations (i.e., the calculated headroom must be greater than or equal to the required headroom). in the case that the calculated head- room is not sufficiently large, relaxing the resolution require- ment or reducing, if possible, the variation of either offset, span, component tolerances, or a combination of all three is required. 7. calculate the maximum offset drift due to temperature fluctuations (defined as the maximum temperature effect on offset). a conservative approach to this calculation is to determine the maximum total voltage change of offset over the application's entire operating temperature range. this maximum change of offset is the product of the gain, tcv off , and the application's entire operating temperature range (from maxtemp to mintemp). since the tempera- ture coefficient of offset can be positive or negative, the offset may increase or decrease with increasing tempera- ture and, likewise, for decreasing temperature. though this step only considers the maximum magnitude of the change in offset due to temperature, a segment in the required headroom is reserved for both possibilities of a positive or negative temperature coefficient of offset (see figure 6). the sign (positive or negative) of the total offset change due to temperature is also considered in upcom- ing steps. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3351 motorola sensor device data www.motorola.com/semiconductors maximum temperature effect on offset = (gain) ? (tcv off ) ? (maxtemp mintemp) max. temperature effect on offset (positive temp. coeff.) max. temperature effect on offset (negative temp. coeff.) required headroom figure 6. the maximum temperature effect on offset 8. calculate the maximum offset variation. the maximum offset variation is the total amount of the required headroom that must be reserved to account for the entire distribution of sensor offsets (at room temperature e refer to figure 7). where largest offset is and the smallest offset is maximum offset variation = [gain] ? [maxsensoff minsensoff] [gain] ? [maxsensoff] [gain] ? [minsensoff] 9. calculate the worst case minimum offset. the worst case minimum offset includes both temperature effects (from step 7) and devicetodevice variations (from step 8) to determine the smallest possible offset over the entire distribution of sensor offsets and over the operating temperature range. this worst case minimum offset occurs when a sensor has a nominal room temperature offset of minsensoff (smallest offset in the sensor offset distribution) and a negative temperature coefficient so that the offset decreases with increasing temperature. refer to figure 7. minimum offset = [gain] ? [minsensoff] maximum temperature effect on offset 10. similar to step 9, calculate the worst case maximum offset. the worst case maximum offset includes both temperature effects (from step 7) and devicetodevice variations (from step 8) to determine the largest possible offset over the entire distribution of sensor offsets and over the operating temperature range. this worst case maximum offset occurs when a sensor has a nominal room temperature offset of maxsensoff (largest offset in the sensor offset distribution) and a positive temperature coefficient so that the offset increases with increasing temperature. refer to figure 7. maximum offset = [gain] ? [maxsensoff] + maximum temperature effect on offset maximum offset minimum offset max. temperature effect on offset (positive temp. coeff.) max. temperature effect on offset (negative temp. coeff.) required headroom max. offset variation (before adding temp. effects) figure 7. calculating the maximum and minimum offsets 11. calculate the required headroom. referring to figure 7, the required headroom is the difference between the maximum offset and minimum offset and is the amount of voltage range (bits of the a/d) required to allow for devicetodevice and temperature variations of the sensor's offset. required headroom = maximum offset minimum offset 12. compare the required headroom of step 11 to the calculated headroom of step 6. the calculated head- room is the absolute maximum amount of offset variation (due to devicetodevice variations and temperature effects) that the system can allow for the desired resolution. if the required headroom is greater than the calculated headroom, the desired resolution is not attainable for all worst case variations due to temperature effects, component tolerances, and devicetodevice variations. therefore, the requirement to attain the desired system resolution is: calculated headroom required headroom if this requirement is not met, as stated previously, the alternatives to meeting this requirement are the following: ? relax the resolution requirement and repeat the meth- odology. ? reduce (tighten) the span or offset (or both) variation and repeat the methodology. ? reduce temperature coefficients. ? reduce the component tolerances and repeat the methodology. ? repeat the methodology by performing a combination of the above suggestions. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3352 motorola sensor device data www.motorola.com/semiconductors once the above headroom requirement is met, the final step is to determine the proper value of v ref : 13. a dc offset, v ref , is required to position the sensor's span within the a/d window so that no devicetodevice or temperature variation nor component tolerances cause the sensor's output to be outside the a/d window. therefore, calculate the v ref required to ensure that the sensor's smallest zeropressure offset voltage (minimum offset) is greater than or equal to v lo (refer to figures 5 and 7). in other words, the sum of the reference voltage and minimum offset must be greater than or equal to the amplifier's low saturation voltage: v ref + minimum offset v lo solving for v ref : v ref v lo minimum offset note: the reference voltage, v ref , also will have variation due to resistor tolerances in the resistor divider used to create v ref . to ensure that the system variation due to resistor tolerances is negligible when compared to other sources of variation, the system should be designed using resistors with tolerances of 1% or better. the following design examples use the methodology. design examples with the mpx10 and mpx2010 the following table lists the methodology's steps. the table entries (names) will correspond to the names used in the methodology outlined above; additionally, the step number (step 1, etc.) is bracketed ( [ ] ) and superscripted next to the entry to which the step refers. the first column lists the given parameters that should be available in or derived from the appropriate component's (sensor, amplifier, voltage regulator, resistors) data sheet. the second column lists the performance requirements of the sensor system (i.e., this column lists all the calculations that relate to ensuring a minimum sensor span to achieve the desired resolution despite devicetodevice variations, temperature effects and component tolerances). the third column lists the calculations that determine the headroom for the system given component tolerances and the devicetodevice variations and temperature effects on the sensor's offset. the table and associated system design equations may easily be implemented in a spreadsheet to efficiently perform the required calculations. table 3. design example using the mpx10 given parameters performance parameters headroom parameters maxfss (mv @ 25 c) 83 [1] resolution (% fss) 4.5 [7] maximum temperature effect on offset (v) 0.03 minfss (mv @ 25 c) 33 [2] number of steps 44 [8] maximum offset variation (v) 1.76 tcv fss (% fss/ c) 0.22 [3] minimum required span (v) 0.87 [9] minimum offset (v) 0.03 maxsensoff (mv @ 25 c) 58 [4] gain 29 [10] maximum offset (v) 1.73 minsensoff (mv @ 25 c) 0 [5] maximum span (v) 2.57 [13] v ref (v) 0.23 tcv off ( m v/ c) 15 v s (v) 5 [6] calculated headroom (v) 1.78 [11] required headroom (v) 1.75 v hi (v) 4.8 v lo (v) 0.2 [12] i s calculated headroom required headroom ? v tol (%) 5 maxtemp ( c) 70 mintemp ( c) 0 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3353 motorola sensor device data www.motorola.com/semiconductors table 4. design example using the mpx2010 given parameters performance parameters headroom parameters maxfss (mv @ 25 c) 13 [1] resolution (% fss) 1.2 [7] maximum temperature effect on offset (v) 0.14 minfss (mv @ 25 c) 12 [2] number of steps 167 [8] maximum offset variation (v) 0.55 tcv fss (% fss) 1 [3] minimum required span (v) 3.27 [9] minimum offset (v) 0.27 maxsensoff (mv @ 25 c) 0.5 [4] gain 275 [10] maximum offset (v) 0.27 minsensoff (mv @ 25 c) 0.5 [5] maximum span (v) 3.61 [13] v ref (v) 0.47 tcv off (mv, 0 c to 85 c) 0.5 v s (v) 5 [6] calculated headroom (v) 0.74 [11] required headroom (v) 0.55 v hi (v) 4.8 v lo (v) 0.2 [12] i s calculated headroom required headroom ? v tol (%) 5 maxtemp ( c) 85 mintemp ( c) 0 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3354 motorola sensor device data www.motorola.com/semiconductors design example comparison summary the preceding examples show how sources of variation can affect the overall system resolution. the mpx2010 has onchip temperature compensation and calibration circuitry to reduce devicetodevice variations and temperature effects. consequently, when designing the fixedvalue amplifier circuitry, the resolution possible with the mpx2010 is almost four times greater than the same amplifier circuit using an mpx10. in both examples, both systems' performance (resolution) are optimized to be the best possible, given the distribution of the sensor device parameters and the other component variations. as stated previously if the methodology's calculations show that the sensor's signal will always be within the dynamic range of the amplifier (and high and low reference voltages of the a/d), a software calibration may then be implemented to nullify any room temperature devicetodevice and component variations. it should be noted, however, that this methodology does not consider how to obtain the best performance from a single sensor system. rather, the focus of the methodology is to obtain the best possible system performance while considering the distribution of device parameters that result from manufacturing and other sources of variation. by considering the sources of variation, the system may then be massproduced without individually calibrating the sensor system hardware. obviously, if each sensor system is handcalibrated, the performance will be better. however, the handcalibration also requires additional cost and time when producing the sensor system. conclusion to guarantee a specified performance when designing a fixedvalue circuit for sensor systems, all significant sources of variation must be considered. by considering the sources of variation (devicetodevice variations, temperature effects, and component tolerances), the system may be designed so that the specified performance (resolution) is achieved while still keeping the sensor's amplified dynamic range within the a/d window (or saturation levels of the amplifier). the specified performance may be achieved in all cases by applying the methodology described herein. by first calculat- ing the minimum required span to achieve the required resolution in all scenarios and then determining if the remaining dynamic range or headroom is large enough to accommodate the sources of variation, the methodology determines if the resolution requirement is feasible. if the sources of variation are too large, the resolution requirement may not be attainable. in such a case, the resolution requirement should be relaxed, or the sources of variation must be decreased. finally, once the system is successfully designed to ensure that the sensor signal will always be within the dynamic range of the amplifier (and high and low reference voltages of the a/d), a software calibration may be implement- ed to nullify any room temperature devicetodevice and component variations. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3355 motorola sensor device data www.motorola.com/semiconductors
prepared by: c.s. chua and siew mun hin sensor application engineering singapore, a/p introduction this application note describes a digital blood pressure meter concept which uses an integrated pressure sensor, analog signalconditioning circuitry, microcontroller hardware/software and a liquid crystal display. the sensing system reads the cuff pressure (cp) and extracts the pulses for analysis and determination of systolic and diastolic pressure. this design uses a 50 kpa integrated pressure sensor (motorola p/n: mpxv5050gp) yielding a pressure range of 0 mmhg to 300 mmhg. concept of oscillometric method this method is employed by the majority of automated noninvasive devices. a limb and its vasculature are compressed by an encircling, inflatable compression cuff. the blood pressure reading for systolic and diastolic blood pressure values are read at the parameter identification point. the simplified measurement principle of the oscillometric method is a measurement of the amplitude of pressure change in the cuff as the cuff is inflated from above the systolic pressure. the amplitude suddenly grows larger as the pulse breaks through the occlusion. this is very close to systolic pressure. as the cuff pressure is further reduced, the pulsation increase in amplitude, reaches a maximum and then diminishes rapidly. the index of diastolic pressure is taken where this rapid transition begins. therefore, the systolic blood pressure (sbp) and diastolic blood pressure (dbp) are obtained by identifying the region where there is a rapid increase then decrease in the amplitude of the pulses respectively. mean arterial pressure (map) is located at the point of maximum oscillation. hardware description and operation the cuff pressure is sensed by motorola's integrated pressure xducer ? . the output of the sensor is split into two paths for two different purposes. one is used as the cuff pressure while the other is further processed by a circuit. since mpxv5050gp is signalconditioned by its internal opamp, the cuff pressure can be directly interfaced with an analogtodigital (a/d) converter for digitization. the other path will filter and amplify the raw cp signal to extract an amplified version of the cp oscillations, which are caused by the expansion of the subject's arm each time pressure in the arm increases during cardiac systole. the output of the sensor consists of two signals; the oscillation signal ( 1 hz) riding on the cp signal ( 0.04 hz). hence, a 2pole high pass filter is designed to block the cp signal before the amplification of the oscillation signal. if the cp signal is not properly attenuated, the baseline of the oscillation will not be constant and the amplitude of each oscillation will not have the same reference for comparison. figure 1 shows the oscillation signal amplifier together with the filter. figure 1. oscillation signal amplifier c2 +5v r2 + +dc offset u1a 3 2 1 150k lm324n 0.33u vi r3 1m 11 4 vo r1 1k c1 33u semiconductor application note f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3356 motorola sensor device data www.motorola.com/semiconductors the filter consists of two rc networks which determine two cutoff frequencies. these two poles are carefully chosen to ensure that the oscillation signal is not distorted or lost. the two cutoff frequencies can be approximated by the following equations. figure 2 describes the frequency response of the filter. this plot does not include the gain of the amplifier. 10 0 10 20 30 40 50 60 70 80 10 100 1 0.1 0.01 frequency (hz) figure 2. filter frequency response oscillation signal (1 hz) cp signal (0.04 hz) attenuation (db) f p1 = 1 2 r 1 c 1 f p2 = 1 2 r 3 c 2 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3357 motorola sensor device data www.motorola.com/semiconductors the oscillation signal varies from person to person. in general, it varies from less than 1 mmhg to 3 mmhg. from the transfer function of mpxv5050gp, this will translate to a voltage output of 12 mv to 36 mv signal. since the filter gives an attenuation of 10 db to the 1 hz signal, the oscillation signal becomes 3.8 mv to 11.4 mv respectively. experiments indicate that, the amplification factor of the amplifier is chosen to be 150 so that the amplified oscillation signal is within the output limit of the amplifier (5 mv to 3.5 v). figure 3(a) shows the output from the pressure sensor and figure 3(b) shows the extracted oscillation signal at the output of the amplifier. figure 3. cp signal at the output of the pressure sensor oscillation signal is extracted here 3 2.5 2 1.5 1 0.5 0 0 5 10 15 20 25 30 35 40 time (seconds) vi (volts) 3 2.5 2 1.5 1 0.5 0 vo (volts) 10 15 20 25 30 35 time (seconds) map dbp sbp 3.5 figure 3b. extracted oscillation signal at the output of amplifier f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3358 motorola sensor device data www.motorola.com/semiconductors referring to the schematic, figure 4, the mpx5050gp pressure sensor is connected to port d bit 5 and the output of the amplifier is connected to port d bit 6 of the microcontroller. this port is an input to the onchip 8bit analogtodigital (a/d) converter. the pressure sensor provides a signal output to the microprocessor of approximately 0.2 vdc at 0 mmhg to 4.7 vdc at 375 mmhg of applied pressure whereas the amplifier provides a signal from 0.005 v to 3.5 v. in order to maximize the resolution, separate voltage references should be provided for the a/d instead of using the 5 v supply. in this example, the input range of the a/d converter is set at approximately 0 vdc to 3.8 vdc. this compresses the range of the a/d converter around 0 mmhg to 300 mmhg to maximize the resolution; 0 to 255 counts is the range of the a/d converter. v rh and v rl are the reference voltage inputs to the a/d converter. the resolution is defined by the following: count = [(v xdcr v rl )/(v rh v rl )] x 255 the count at 0 mmhg = [(0.2 0)/(3.8 0)] x 255 14 the count at 300 mmhg = [(3.8 0)/(3.8 0)] x 255 255 therefore the resolution = 255 14 = 241 counts. this translates to a system that will resolve to 1.24 mmhg. the voltage divider consisting of r5 and r6 is connected to the +5 volts powering the system. the output of the pressure sensor is ratiometric to the voltage applied to it. the pressure sensor and the voltage divider are connected to a common supply; this yields a system that is ratiometric. by nature of this ratiometric system, variations in the voltage of the power supplied to the system will have no effect on the system accuracy. the liquid crystal display (lcd) is directly driven from i/o ports a, b, and c on the microcontroller. the operation of a lcd requires that the data and backplane (bp) pins must be driven by an alternating signal. this function is provided by a software routine that toggles the data and backplane at approximately a 30 hz rate. other than the lcd, there are two more i/o devices that are connected to the pulse length converter (plm) of the microcontroller; a buzzer and a light emitting diode (led). the buzzer, which connected to the plma, can produce two different frequencies; 122 hz and 1.953 khz tones. for instance when the microcontroller encounters certain error due to improper inflation of cuff, a low frequency tone is alarm. in those instance when the measurement is successful, a high frequency pulsation tone will be heard. hence, different musical tone can be produced to differential each condition. in addition, the led is used to indicate the presence of a heart beat during the measurement. the microcontroller section of the system requires certain support hardware to allow it to function. the mc34064p5 provides an undervoltage sense function which is used to reset the microprocessor at system powerup. the 4 mhz crystal provides the external portion of the oscillator function for clocking the microcontroller and provides a stable base for time based functions, for instance calculation of pulse rate. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3359 motorola sensor device data www.motorola.com/semiconductors figure 4. blood pressure meter schematic drawing pc0 pc1 pc2/eclk pc3 pc4 pc5 pc6 pc7 pd0/an0 +5v +5v +5v +5v +5v +5v +5v +5v pressure sensor mpxv5050gp vout gnd 2 3 vs 9v battery c5 1 1 2 gnd 0.33u input output 5v regulator mc78l05acp buzzer 0.33u c2 3 1 3 2 r4 r0 10k 24k r3 1m 11 lm324n 4 r1 c1 1k 33u 150k r2 c7 led r8 100r 100n 100u c8 c6 330u r10 10m x1 4mhz c3 c4 22p 22p pd1/an1 pd2/an2 pd3/an3 pd4/an4 pd5/an5 pd6/an6 pd7/an7 plmb plma sclk tdo tcmp2 tcmp1 vdd osc2 mc68hc05b16cfn osc1 /reset /irq tcap1 tcap2 rd vrh vrl pa0 pa1 pa2 pa3 pa4 pa5 pa6 pa7 pb0 pb1 pb2 pb3 pb4 pb5 pb6 pb7 r6 r5 4.7k + 36r 15k r9 4.7k +5v mc34064 reset input gnd lcd5657 1 3 2 17 10 2 1 52 51 20 21 49 48 47 46 45 44 43 42 14 13 12 11 9 5 4 3 32 33 34 35 36 37 38 39 24 25 26 27 28 29 30 31 7 8 50 23 22 19 18 16 16 23 22 21 20 19 18 17 12 27 26 25 24 15 14 13 cb a g 1 d dp ef 2 dp ll 3 dp 4 dp1 g1 f1 a1 b1 c1 d1 e1 dp2 g2 f2 a2 b2 c2 d2 e2 37 36 35 34 7 6 5 28 40 1 8 32 31 30 29 11 10 9 g4 f4 a4 b4 c4 d4 e4 l bp bp dp3 g3 f3 a3 b3 c3 d3 e3 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3360 motorola sensor device data www.motorola.com/semiconductors software description upon system powerup, the user needs to manually pump the cuff pressure to approximately 160 mmhg or 30 mmhg above the previous sbp. during the pumping of the inflation bulb, the microcontroller ignores the signal at the output of the amplifier. when the subroutine take senses a decrease in cp for a continuous duration of more than 0.75 seconds, the microcontroller will then assume that the user is no longer pumping the bulb and starts to analyze the oscillation signal. figure 5 shows zoomin view of a pulse. 7.1 7.3 7.5 7.7 7.9 8.1 8.3 8.5 time (second) figure 5. zoomin view of a pulse vo (volt) 450 ms premature pulse 1.75 first of all, the threshold level of a valid pulse is set to be 1.75 v to eliminate noise or spike. as soon as the amplitude of a pulse is identified, the microcontroller will ignore the signal for 450 ms to prevent any false identification due to the presence of premature pulse oovershooto due to oscillation. hence, this algorithm can only detect pulse rate which is less than 133 beats per minute. next, the amplitudes of all the pulses detected are stored in the ram for further analysis. if the microcontroller senses a nontypical oscillation envelope shape, an error message (aerro) is output to the lcd. the user will have to exhaust all the pressure in the cuff before repumping the cp to the next higher value. the algorithm ensures that the user exhausts all the air present in the cuff before allowing any repumping. otherwise, the venous blood trapped in the distal arm may affect the next measurement. therefore, the user has to reduce the pressure in the cuff as soon as possible in order for the arm to recover. figure 6 is a flowchart for the program that controls the system. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3361 motorola sensor device data www.motorola.com/semiconductors figure 6. main program flowchart main program initialization clear i/o ports display ocalo and output a musical tone clear all the variables take in the amplitude of all the oscillation signal when the user has stop pumping calculate the sbp and dbp and also the pulse rate repump? is there any error in the calculation or the amplitude envelope detected? output a high frequency musical tone exhaust cuff before repump exhaust cuff before repump display pulse rate. display osyso follow by sbp. display odlao follow by dbp. display oerro output a low frequency alarm n n n n y y y y f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3362 motorola sensor device data www.motorola.com/semiconductors selection of microcontroller although the microcontroller used in this project is mc68hc05b16, a smaller rom version microcontroller can also be used. the table below shows the requirement of microcontroller for this blood pressure meter design in this project. table 1. selection of microcontroller onchip rom space 2 kilobytes onchip ram space 150 bytes 2channel a/d converter (min.) 16bit free running counter timer lcd driver onchip eeprom space 32 bytes power saving stop and wait modes conclusion this circuit design concept may be used to evaluate motorola pressure sensors used in the digital blood pressure meter. this basic circuit may be easily modified to provide suitable output signal level. the software may also be easily modified to provide better analysis of the sbp and dbp of a person. references lucas, bill (1991). aan evaluation system for direct interface of the mpx5100 pressure sensor with a microprocessor,o motorola application note an1305. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3363 motorola sensor device data www.motorola.com/semiconductors prepared by: david heeley systems and applications engineering motorola semiconductor products sector sensor products division phoenix, arizona introduction fluid systems, pressure and pressure measurements are extremely complex. the typical college curriculum for mechanical engineers includes at least two semesters in fluid mechanics. this paper will define and explain the basic concepts of fluid mechanics in terms that are easily understood while maintaining the necessary technical accuracy and level of detail. pressure and pressure measurement what is fluid pressure? fluid pressure can be defined as the measure of force perunitarea exerted by a fluid, acting perpendicularly to any surface it contacts (a fluid can be either a gas or a liquid, fluid and liquid are not synonymous). the standard si unit for pressure measurement is the pascal (pa) which is equivalent to one newton per square meter (n/m 2 ) or the kilopascal (kpa) where 1 kpa = 1000 pa. in the english system, pressure is usually expressed in pounds per square inch (psi). pressure can be expressed in many different units including in terms of a height of a column of liquid. the table below lists commonly used units of pressure measurement and the conversion between the units. kpa mm hg millibar in h2o psi 1 atm 101.325 760.000 1013.25 406.795 14.6960 1 kpa 1.000 7.50062 10.000 4.01475 0.145038 1 mm hg 0.133322 1.000 1.33322 0.535257 0.0193368 1 millibar 0.1000 0.750062 1.000 0.401475 0.0145038 1 in h2o 0.249081 1.86826 2.49081 1.000 0.0361 1 psi 6.89473 51.7148 68.9473 27.6807 1.000 1 mm h2o 0.009806 0.07355 9.8 x 10 8 0.03937 0.0014223 figure 1. conversion table for common units of pressure pressure measurements can be divided into three different categories: absolute pressure, gage pressure and differential pressure . absolute pressure refers to the absolute value of the force perunitarea exerted on a surface by a fluid. therefore the absolute pressure is the difference between the pressure at a given point in a fluid and the absolute zero of pressure or a per fect vacuum. gage pressure is the measurement of the difference between the absolute pressure and the local atmospheric pressure. local atmospheric pressure can vary depending on ambient temperature, altitude and local weather conditions. the u.s. standard atmospheric pressure at sea level and 59 f (20 c) is 14.696 pounds per square inch absolute (psia) or 101.325 kpa absolute (abs). when referring to pressure measurement, it is critical to specify what reference the pressure is related to. in the engl ish system of units, measurement relating the pressure to a reference is accomplished by specifying pressure in terms of pounds per square inch absolute (psia) or pounds per square inch gage (psig). for other units of measure it is important to specify gage or absolute. the abbreviation `abs' refers to an absolute measurement. a gage pressure by convention is always positive. a `negati ve' gage pressure is defined as vacuum. vacuum is the measurement of the amount by which the local atmospheric pressure exceeds the absolute pressure. a perfect vacuum is zero absolute pressure. figure 2 shows the relationship between absolute, gage pressure and vacuum. differential pressure is simply the measurement of one unknown pressure with reference to another unknown pressure. the pressure measured is the difference between the two unknown pressures. this type of pressure measurement is commonly used to measure the pressure drop in a fluid system. since a differential pressure is a measure of one pressure referenced to another, it is not necessary to specify a pressure reference. for the english system of units this could simply be psi and for the si system it could be kpa.

semiconductor application note f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3364 motorola sensor device data www.motorola.com/semiconductors pressure local atmospheric pressure vacuum (negative gage) absolute absolute atmospheric gage figure 2. pressure term relationships in addition to the three types of pressure measurement, there are different types of fluid systems and fluid pressures. there a re two types of fluid systems; static systems and dynamic systems . as the names imply, a static system is one in which the fluid is at rest and a dynamic system is on in which the fluid is moving. static pressure systems the pressure measured in a static system is static pressure . in the pressure system shown in figure 3, a uniform static fluid is continuously distributed with the pressure varying only with vertical distance. the pressure is the same at all points alon g the same horizontal plane in the fluid and is independent of the shape of the container. the pressure increases with depth in the f luid and acts equally in all directions. the increase in pressure at a deeper depth is essentially the effect of the weight of the f luid above that depth. figure 4 shows two containers with the same fluid exposed to the same external pressure p . at any equal depth within either tank the pressure will be the same . note that the sides of the large tank are not vertical. the pressure is dependent o nly on depth and has nothing to do with the shape of the container. if the working fluid is a gas, the pressure increase in the flu id due to the height of the fluid is in most cases negligible since the density and therefore the weight of the fluid is much smaller than the pressure being applied to the system. however, this may not remain true if the system is large enough or the pressures low enou gh. one example considers how atmospheric pressure changes with altitude. at sea level the standard u.s. atmospheric pressure is 14.696 psia (101.325 kpa). at an altitude of 10,000 ft (3048 m) above sea level the standard u.s. atmospheric pressure is 10 .106 psia (69.698 kpa) and at 30,000 ft (9144 m), the standard u.s. atmospheric pressure is 4.365 psia (30.101 kpa). the pressure in a static liquid can be easily calculated if the density of the liquid is known. the absolute pressure at a dept h h in a liquid is defined as: p abs = p + ( r x g x h) where : p abs is the absolute pressure at depth h. p is the external pressure at the top of the liquid. for most open systems this will be atmospheric pressure. r is the density of the fluid. g is the acceleration due to gravity (g = 32.174 ft/sec 2 (9.81 m/sec 2 )). h is the depth at which the pressure is desired. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3365 motorola sensor device data www.motorola.com/semiconductors ???????????????????????? ???????????????????????? ???????????????????????? ???????????????????????? ???????????????????????? ???????????????????????? ???????????????????????? ??????????????? ??????????????? ??????????????? ??????????????? ??????????????? ??????????????? ??????????????? ??? ??? ??? ??? ??? ??? ??? figure 3. continuous fluid system figure 4. pressure measurement at a depth in a liquid dynamic pressure systems dynamic pressure systems are more complex than static systems and can be more difficult to measure. in a dynamic system, pressure typically is defined using three different terms. the first pressure we can measure is static pressure . this pressure is the same as the static pressure that is measured in a static system. static pressure is independent of the fluid movement or flow. as with a static system the static pressure acts equally in all directions. the second type of pressure is what is referred to as the dynamic pressure . this pressure term is associated with the velocity or the flow of the fluid. the third pressure is total pressure and is simply the static pressure plus the dynamic pressure. steadystate dynamic systems care must be taken when measuring dynamic system pressures. for a dynamic system, under steadystate conditions, accurate static pressures may be measured by tapping into the fluid stream perpendicular to the fluid flow. for a dynamic syste m, steadystate conditions are defined as no change in the system flow conditions: pressure, flow rate, etc. figure 5 illustrates a dynamic system with a fluid flowing through a pipe or duct. in this example a static pressure tap is located in the duct wall a t point a. the tube inserted into the flow is called a pitot tube. the pitot tube measures the total pressure at point b in the system . the total pressure measured at this point is referred to as the stagnation pressure . the stagnation pressure is the value obtained when a flowing fluid is decelerated to zero velocity in an isentropic (frictionless) process. this process converts all of the energ y from the flowing fluid into a pressure that can be measured. the stagnation or total pressure is the static pressure plus the dynami c pressure. it is very difficult to accurately measure dynamic pressures. when dynamic pressure measurement is desired, the total and static pressures are measured and then subtracted to obtain the dynamic pressure. dynamic pressures can be used to determine the fluid velocities and flow rates in dynamic systems. when measuring dynamic system pressures, care must be taken to ensure accuracy. for static pressure measurements, the pressure tap location should be chosen so that the measurement is not influenced by the fluid flow. typically, taps are located perpendicular to the flow field. in figure 5, the static pressure tap at point a is in the wall of the duct and perpendicular t o the flow field. in figures 6a and 6c the static taps (point a) in the pressure probes are also perpendicular to the flow field. these ex amples show the most common type of static pressure taps, however there are many different static pressure tap options. for total or stagnation pressure measurements, it is important that the pitot or impact tube be aligned parallel to the flow field with th e tip of the tube pointing directly into the flow. in figures 6b and 6c, the pitot tube is aligned parallel with the flow, with the t ube opening pointing directly into the flow. although the static pressure is independent of direction, the dynamic pressure is a vector qua ntity which depends on both magnitude and direction for the total measured value. if the pitot tube is misaligned with the flow, accu racy of the total pressure measurement may suffer. in addition, for accurate pressure measurements the pressure tap holes and probes must be smooth and free from any burrs or obstructions that could cause disturbances in the flow. the location of the pressure taps and probes, static and total, must also be selected carefully. any location in the system where the flow field may be dist urbed f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3366 motorola sensor device data www.motorola.com/semiconductors should be avoided, both upstream and downstream. these locations include any obstruction or change such as valves, elbows, flow splits, pumps, fans, etc. to increase the accuracy of pressure measurement in a dynamic system, allow at least 10 pipe / duct diameters downstream of any change or obstruction and at least 2 pipe / duct diameters upstream. in addition the pipe / du ct diameter should be much larger than the diameter of the pitot tube. the pipe / duct diameter should be at least 30 times the pi tot tube diameter. flow straighteners can also be used to minimize any variations in the direction of the flow. also, when using a pitot tube, it is recommended that the static pressure tap be aligned in the same plane as the total pressure tap. on the pitotstati c tube, the difference in location is assumed to be negligible. flowthrough pipes and ducts will result in a velocity field and dynamic pressure field that are nonuniform. at the wall of an y duct or pipe there exists a noslip boundary due to friction. this means that at the wall itself the velocity of the fluid is z ero. figure 5 shows an imaginary velocity distribution in a duct. the shape of the distribution will depend on the fluid conditions, system flow and pressure. in order to accurately determine the average dynamic pressure across a duct section, a series of total pressure readings must be taken across the duct. these pressure measurements should be taken at different radii and clock positions across the cross section of a round duct or at various width and height locations for a rectangular duct. once this characteriz ation has been performed for the duct , a correlation can be easily made between the total pressure measurement at the center of the duct relative to the average duct total pressure. this technique is also used to determine the velocity profile within the duct . velocity distribution static pressure tap pitot tube b a (a) static pressure probe (b) total pressure pitot tube (c) combination static pressure and total pressure pitot tube (pitotstatic tube) flow flow flow bb a a p s p s p o p o figure 5. static and total pressure measurements within a dynamic fluid system. figure 6. types of pressure probes f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3367 motorola sensor device data www.motorola.com/semiconductors transient systems transient systems are systems with changing conditions such as pressures, flow rates, etc. measurements in transient systems are the most difficult to accurately obtain. if the measurement system being used to measure the pressure has a faster response time than the rate of change in the system, then the system can be treated as quasisteadystate. that is, the measurements wil l be about as accurate as those taken in the steadystate system. if the measurement of the system is assumed to be a snap shot of what is happening in the system, then you want to be able to take the picture faster than the rate of change in the system o r the picture will be blurred. in other words, the measurement results will not be accurate. in a pressure measurement system, th ere are two factors that determine the overall measurement response: (1) the response of the transducer element that senses the pressure, and (2) the response of the interface between the transducer and the pressure system such as the pressure transmittin g fluid and the connecting tube, etc. for motorola pressure sensors, the second factor usually determines the overall frequency response of the pressure measurement system. the vast majority of pressure systems that require measurements today are quasisteadystate systems where system conditions are changing relatively slowly compared to the response rate of the measurement system or the change happens instantaneously and then stabilizes. two transient system examples include washing machines and ventilation ducts in buildings. in a washing machine, the height of the water in the tub is measured indirectly by measuring the pressure at the bottom of the tub. as the tub fills the pressur e changes. the rate at which the tub fills and the pressure changes is much slower than the response rate of the measurement system. in a ventilation duct, the pressure changes as the duct registers are opened and closed, adjusting the air movement wit hin the building. as more registers are opened and closed, the system pressure changes. the pressure changes are virtually instantaneous. in this case, pressure changes are essentially incremental and therefore easy to measure accurately except at th e instant of the change. for most industrial and building control applications, the lag in the pressure measurement system is negligible. as the control or measurement system becomes more precise, the frequency response of the measurement system must be considered. motorola pressure sensors this application note has covered various types of pressures that are measured and how to tap into a system to measure the desired pressures. how are the actual pressure measurements made? there are many types of pressure measurement systems ranging from simple liquid tube manometers to bourdontube type gages to piezoelectric silicon based transducers. today, as electronic control and measurement systems are replacing mechanical systems, siliconbased pressure transducers and sensors are becoming the sensors of choice. silicon micromachined sensors offer very high accuracies at very low cost and provide an interface between the mechanical world and the electrical system. motorola carries a complete line of silicon based pressure sensors which feature a wide range of pressures with various levels of integration on a single chip. these levels of integratio n start with the basic uncompensated, uncalibrated pressure sensor all the way to the fully integrated, temperature compensated, calibrated and signal conditioned pressure sensors. the response time of motorola's mpx series silicon pressure sensors is typically 1 millisecond or less. for static or dynamic systems, motorola's pressure sensors are an excellent solution for pr essure measurement systems. conclusion pressures and pressure measurements can be extremely complex and complicated. however, for most systems it is relatively easy to obtain accurate pressure measurements if the proper techniques are used. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3368 motorola sensor device data www.motorola.com/semiconductors by: eric jacobsen systems and applications engineer sensor products division motorola, inc. a digital output is more desirable than an analog output in noisy environments (e.g. automotive, washing machines, etc.) and remote sensing applications (building controls, industrial applications, etc.) because a digital signal inherently has better noise immunity compared to analog signals. additional applications requiring a sensor with a digital output include microcontrollerbased systems that have no a/d in the system or that have no a/d channels available for the sensing function. for these applications, there is no other option but a digital output to further process the signal. via a design example this paper shows how to easily convert an analog voltage output sensor to a digital output sensor. for the design example, each of the required circuit components is discussed in detail. while the design is applicable to analog voltage output sensors (differential or singleended output) in general, the design example and following discussions will pertain specifically to semiconductor pressure sensors. the digital output sensor in figure 1. consists of the following: ? motorola mpx2000 series pressure sensor ? a two op amp gain stage to amplify the sensor's signal ? an integrator (i.e. a low pass filter consisting of one resistor and one capacitor) ? an lm311 comparator ? an mc68hc05p9 microcontroller with which only two pins are used: the output compare timer channel (tcmp) and one general i/o pin (the input capture timer channel, tcap, can be used in place of the general i/o pin). since only two of the mc68hc05p9's pins are used, the remaining pins are available for other system functions. figure 1. the digital output sensor schematic amplifier comparator integrator to mc68hc05p9's general i/o pin or tcap pin pressure sensor + + from mc68hc05p9's tcmp pin + r6 +5 v r5 c1 r4 r2 u1 mc33272 u1 mc33272 +5 v +5 v u2 lm311 r3 r+shift1 r+shift2 r1 +5 v x1 mpx2000 series 2 4 3 1 +5 v rh (optional)
semiconductor application note f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3369 motorola sensor device data www.motorola.com/semiconductors after the discussion of the circuit components, the following systemrelated issues will be discussed simultaneously using the design example: ? how the system works ? defining and designing the digital output for a desired sig- nal resolution ? a stepbystep procedure that shows you how to digitize the signal ? a procedure to show you how to software calibrate the digi- tal output ? related software examples this system, in addition to the benefits of a digital output (noise immunity, etc.), also has the following additional inherent benefits. these benefits will be addressed in more detail in the systems topics. ? the circuit topology and method of adigitizingo the sensor's analog output is very stable and accurate. the system uses the microcontroller's precise, internal, digital time base to digitize the analog signal. ? the signal resolution is userprogrammable via software e i.e. the user can program whether the resolution is 8bit, 10bit, etc. ? the digital output is calibrated in software so that compo- nent tolerances can be nullified. ? the software required to digitize the signal requires very little cpu time and overhead. ? the required circuitry is minimal, simple, and costeffec- tive. the pressure sensor motorola's mpx2000 series sensors are temperature compensated and calibrated (i.e. offset and span are precision trimmed) pressure transducers. these sensors are available in full scale pressure ranges from 10 kpa (1.5 psi) to 700 kpa (100 psi). although the specifications (see table 1) in the data sheets apply to a 10 v supply voltage, the output of these devices is ratiometric with the supply voltage. for example, at the absolute maximum supply voltage rating, 16 v, the sensor will typically produce a differential output voltage of 64 mv at the rated full scale pressure of the given sensor. one exception to this is that the span of the mpx2010 (10 kpa sensor) will be only 40 mv due to the device's slightly lower sensitivity. since the maximum supply voltage produces the largest output signal, it is evident that even the best case scenario will require some signal conditioning to obtain a usable signal (input to an a/d, etc.). for this specific design, an mpx2100 and 5.0 v supply are used, yielding a typical maximum sensor output of 20 mv (typical zero pressure offset is 0.0 mv and typical span is 20 mv). the sensor's output is then signal conditioned (amplified and level shifted) to provide a four volt span with a zero pressure offset of 0.5 v. table 1. mpx2100 electrical characteristics for v s = 10 v, t a = 25 c characteristic symbol min typ max unit pressure range p op 0 100 kpa supply voltage v s 10 16 vdc full scale span v fss 38.5 40 41.5 mv zero pressure off- set v off 1.0 1.0 mv sensitivity d v/ d p 0.4 mv/kpa linearity e 0.25 0.25 %v fss temperature effect on span tcv fss 1.0 1.0 %v fss temperature effect on offset tcv off 1.0 1.0 mv amplifier stage the amplifier circuitry, shown in figure 1. , is composed of two op amps. this interface circuit has a much lower component count than conventional quad op amp instrumentation amplifiers. the two op amp design offers the high input impedance, low output impedance, and high gain desired for a transducer interface, while performing a differential to singleended conversion. the amplifier incorporates level shifting capability. the amplifier has the following transfer function: v o 1 r4 r3 ? (v sensor ) + v + shift where r1 = r4, r2 = r3, the gain is 1 r4 r3 , v sensor is the sensor's differential output (s + s ), and v+shift is the positive dc level shift voltage created by the resistor divider comprised of r+shift1 and r+shift2. v+shift is used to position the zero pressure offset at the desired level. table 2 summarizes the 1% resistor values used to obtain a four volt span with a zero pressure offset of 0.5 v (assuming the typical sensor offset and span values of 0.0 mv and 20 mv, respectively). table 2. resistor values for the mpx2100 amplifier design r+shift1 r+shift2 r1 r2 r3 r4 4.99 k w 549 w 20.0 k w 100 w 100 w 20.0 k w f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3370 motorola sensor device data www.motorola.com/semiconductors the integrator as shown in figure 1. , the integrator consists of a single resistor and single capacitor. a programmable duty cycle pulse train from the microcontroller is input to the integrator. assuming that the rc time constant of the integrator is sufficiently long compared to the pulse train's frequency, the resulting output which is input to the inverting terminal of the comparator is a dc voltage that is linearly proportional to the pulse train's duty cycle, i.e.: dc output voltage = pulse train's duty cycle (%) ? 5 v where the pulse train's duty cycle is multiplied by the pulse train's logiclevel one voltage value which is typically the same voltage as the microcontroller's 5 v supply. table 3 shows a few examples of pulse train duty cycles and the corresponding dc output voltage assuming a typical pulse train logiclevel one value of 5 v. table 3. example pulse train duty cycles and the integrator's corresponding dc voltage output pulse train's duty cycle (%) 0 25 50 75 100 dc output voltage (v) 0 1.25 2.5 3.75 5 to establish a stable constant dc voltage at the integrator's output, its time constant must be sufficiently long compared to the frequency of the pulse train. however, the system resolution and thus performance are directly related to the pulse train's frequency. the design of the time constant and choice of the resistor and capacitor values is discussed in system design: defining and designing for a desired signal resolution. comparator the lm311 chip is designed specifically for use as a comparator and thus has short delay times, high slew rate, and an opencollector output. a pullup resistor (r6 = 5 k w ) at the output is all that is needed to obtain a railtorail output. as figure 1. shows, the pressure sensor's amplified output voltage is input to the noninverting terminal of the op amp and the integrator's dc output voltage is input to the inverting terminal. therefore, when the pressure sensor's output voltage is greater than the integrator's dc output voltage, the comparator's output is high (logiclevel one); conversely, when the pressure sensor's output voltage is less than the integrator's dc output voltage, the comparator's output is low (logiclevel zero). an optional resistor, rh is used as positive feedback around u2 in figure 1 to provide a small amount of hysteresis to ensure a clean logiclevel transition (prevents multiple transitions (squegging)) when the comparator's inputs are similar in value. the amount of hysteresis increases as the value of rh decreases. for this design, the value of rh is not critical but should be on the order of 100 k w . the mc68hc05p9 microcontroller the microcontroller for this application requires an output compare timer channel and one general i/o pin. the output compare pin is programmed to output the pulse train that is input to the integrator, and the general i/o pin is configured as an input to monitor the logiclevel of the comparator's output. the remainder of this paper discusses the system and software requirements. system design: how the system works for any analog sensor voltage output, there's a pulse train with a duty cycle that when integrated will equal the sensor's output. therefore, by incrementing via software the pulse train's duty cycle from 0% to 100%, there's a duty cycle that when integrated will be larger than the sensor's current voltage output. when the integrated pulse train voltage becomes larger than the sensor's output voltage, the comparator's output will change from a logiclevel one to a logiclevel zero. this logiclevel, in turn, is monitored on the general i/o pin. the pulse train's duty cycle creating the integrated voltage that caused the comparator's logiclevel transition is the digital representation of the sensor's voltage. thus every sensor analog output voltage is mapped to a specific duty cycle. this design inherently has outstanding performance (very stable and accurate) since the digital representation of the sensor signal is created by the microcontroller's digital time base. also the pressure measurement, made via software that first increments the pulse train's duty cycle and then determines if an edge transition occurred on the general i/o pin, is straightforward and easy. in a calibration routine (discussed below) the sensor's output at two known pressures (e.g. zero and fullscale pressure) can be mapped to two corresponding pulse train duty cycles. since the pressure sensor's output voltage is linear with the applied pressure, and the integrator's dc output voltage is linear with the input pulse train duty cycle, then the pulse train's duty cycle that causes the logiclevel transition at the comparator's output will also be linear with the applied pressure. thus by knowing the duty cycles for two known pressures, a linear interpolation of any duty cycle gives an accurate measurement of the current pressure. the following equation is used to interpolate the pressure measurement where the pressure units are in kpa: duty cycle @ fullscale pressure duty cycle @ zero pressure current duty cycle duty cycle @ zero pressure ? fullscale pressure in kpa current pressure = for example: at zero pressure, if the pulse train's duty cycle required to cause a logiclevel transition at the comparator's output is 25% and at fullscale pressure the pulse train's duty cycle is 75%, then the current pressure that corresponds to a duty cycle of 50% (required to obtain the logiclevel one to logiclevel zero transition at the comparator's output) is current pressure 50% 25% 75% 25% ? 100 kpa = 50 kpa until now, the pulse train has been defined in terms of duty cycle. however, in practice duty cycle is calculated from the ratio of the high time to the total period of the pulse train. therefore, there is a high time (typically in m s) of the pulse train that causes the logiclevel transition of the comparator's output. the interpolation of the current pressure can then be calculated directly from the high time of the pulse train that is programmed by the user to be generated by the f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3371 motorola sensor device data www.motorola.com/semiconductors microcontroller's output compare pin. the equation is similar to the one above for current pressure: high time @ fullscale pressure high time @ zero pressure current high time high time @ zero pressure ? fullscale pressure in kpa current pressure = via this equation, the digital nature of the design is revealed. the analog voltage signal has been translated into a signal in the time domain where the high time generated by the output compare pin is actually the digital time representation of the sensor's output. since the user precisely controls the high time of the pulse train (and period) via software which is based on the accurate digital time base of the microcontroller, the digital representation of the signal is very stable and accurate. additionally, the high accuracy of the digital representation is possible since all the user must do to digitize the signal is detect a single logiclevel transition at the comparator's output. system design: defining and designing for a desired signal resolution the resolution is directly related to the period (and thus frequency) of the pulse train. in our design, the difference between the pulse train's high time at full scale pressure and the pulse train's high time and zero pressure must be 512 m s to obtain at least 8bit resolution. this is determined by the fact that a 4 mhz crystal yields a 2 mhz clock speed in the mc68hc05p9 microcontroller. this, in turn, translates to 0.5 m s per clock tick. there are four clock cycles per timer count. this results in 2 m s per timer count. thus, to obtain 256 timer counts (discrete hightime time intervals or 8bit resolution), the difference between the zero pressure and full scale pressure high times must be at least 2 m s x 256 = 512 m s. to determine the pulse train's maximum frequency (or minimum period), the sensor's analog dynamic range (span) must be known. for this design, the span is 4 v. thus the 4 v span of the sensor must translate to 512 m s of time for 8bit resolution. but the pulse train typically has a logiclevel high value of 5 v, indicating that for a 100% duty cycle or a period with all high time, the integrator's output would be 5 v; likewise for a duty cycle of 0% or a period with no high time, the output would be 0 v. therefore 512 m s accounts for only 4 v/5 v (80%) of the pulse train's total period. see figure 2. . to calculate the pulse train's total period, divide the 512 m s by 4/5 (0.8) to obtain the required minimum period for the pulse train of 640 m s. the reciprocal of this minimum period is the maximum frequency (1.56 khz) of the pulse train to obtain at least 8bit resolution. to summarize: the mc68hc05p9 runs off a 4 mhz crystal. the microcontroller internally divides this frequency by two to yield an internal clock speed of 2 mhz. 1 2mhz 0.5 s clock cycle and, 4 clock cycles = 1 timer count. therefore, 4 clock cycles timer count 0.5 s clock cycle 2 s timer count ? for 8bit resolution, 2 s timer count ? 256 timer counts = 512 m s which is the required minimum time into which the sensor's 4 v span is translated. to calculate the required period of the pulse train to yield the 0 to 5 v output (from 0% to 100% duty cycle based on the pulse train's logiclevel high value of 5 v): 512 s for a 4 v sensor span 4 5 of integrator s output 640 s minimum required period = translating this to frequency, the maximum pulse train frequency is thus 1 640 s 1.56 khz. the above procedure can be implemented easily for other resolution requirements (i.e. a resolution of 1%, 2%, etc.). figure 2. designing the pulse train's period for 8bit resolution 5 v (pulse train's logiclevel one value) 4.5 v (sensor's analog voltage output at fullscale pressure) 0.5 v (sensor's analog voltage output at zero pressure) 0 v (pulse train's logiclevel zero value) 4.0 v span pulse train high time of 640 s (100% duty cycle) pulse train high time of 576 s pulse train high time of 64 s 512 s for 8bit resolution pulse train high time of 0 s (0% duty cycle) f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3372 motorola sensor device data www.motorola.com/semiconductors important note: very small and very large high times (assuming a fixed period) are typically unattainable due to the finite amount of time it takes to generate the pulse train on the output compare pin. this amount of time will vary depending on the microcontroller's clock speed and the latency of the actual software routines implemented. thus the sensor's analog voltage to which the integrator's dc voltage is compared must be within the possible ranges of voltages created by the integrator's input pulse train e i.e. the sensor's zero pressure offset voltage must be greater than the smallest voltage created by the integrator (corresponding to the pulse train's smallest possible high time) and the sensor's full scale output voltage must be less than the largest voltage created by the integrator (corresponding to the pulse train's largest possible high time). after establishing the frequency of the pulse train, the rc time constant for the integrator can be determined and the resistor and capacitor value can be chosen. the rc time constant should be long compared to the period of the pulse train so that a stable dc voltage (very little ripple due to the capacitor's charging and discharging) is obtained at the output of the comparator. follow these steps to design the rc time constant and integrator's component values. the design example's calculations are presented simultaneously. for the resolution desired, determine the number of volts (typically mv) that corresponds to the least significant bit (one timer count). for this design example, 8bit resolution (256 timer counts) over the desired pressure sensor span corresponds to #of mv timer count desired pressure sensor span (v) number of timer counts 4v 256 timer counts 15.6 mv timer count therefore the stability of the integrator's output voltage should be less than 15.6 mv (least significant bit). choosing an rc time constant that allows a ripple of approximately onefourth of the least significant bit is sufficient (approximately 3.9 mv). the most ripple occurs at a 50% duty cycle pulse train. for this design the entire period is 640 m s. 50% duty cycle indicates a high time (and low time) of 320 m s. furthermore, the capacitor should discharge no more than approximately 3.9 mv (defined as d v) over the 320 m s. the following equation is used to calculate the value for rc: t rc v(t) = v initial d v = pulse train logiclevel one value ? duty cycle ? e where v initial = pulse train logiclevel one value ? duty cycle and d v is the voltage discharge of the capacitor. solving for rc: t ln v(t) pulse train logiclevel one value duty cycle ? rc = 320 s ln 2.5v3.9mv 5 v 50% 0.205 s ? finally, choose the values of the resistor and capacitor. a typical resistor value is on the order of a tens of k w . the resistor's value can be higher (hundreds of k w ) but care must be taken to avoid increased thermal noise. for this design, the resistor value is chosen to be 49.9 k w (1% resistor). the capacitor's value is readily calculated to be c 0.205 s 49.9 k 4.1 f choose the values of the resistor and capacitor so that the actual time constant is equal to or greater than the calculated time constant. note: be aware that temperature variations can create errors in the system (thus reducing system performance); therefore, be sure to use low temperature coefficient resistors, capacitors, etc. system design: stepbystep procedure for pressure measurement and calibration to measure pressure (note: there are other measurement algorithms that can be performed that in some cases may be more acceptable (see below, additional notes)): 1. start with a pulse train with the minimum high time feasible with the system's microcontroller. pulse train should run at a frequency equal to or less than the frequency calculated above. 2. make sure the general i/o pin's input is high (sensor's output voltage is greater than the integrator's output voltage). 3. increment the high time of the pulse train by one timer count. 4. check the general i/o pin to see if its input is low (sensor's output voltage has become less than the integrator's output voltage). 5. if the general i/o pin is reading a logiclevel zero, store in memory the high time of the pulse train as the current pressure high time reading that created the logiclevel transition in the comparator's output. 6. if the general i/o pin is reading a logiclevel one, go back to step 3 and repeat. 7. using the equation acurrent pressure = .......o shown above, calculate the current pressure (assuming the system has already been calibrated). 8. repeat steps 1 through 7 for additional pressure measurements. to calibrate the system: at zero and full scale pressures, perform the above 8 step pressure measurement routine. store the appropriate pulse train high times corresponding to zero and full scale pressure. these high times will be used to calculate the current pressure as mentioned in step 7 above. software examples to generate pulse train on output compare timer channel the following software examples are written in assembly language for the mc68hc05p9 (the code is applicable to any hc05 series microcontroller with tcmp pin). f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3373 motorola sensor device data www.motorola.com/semiconductors * generates the pulse train on tcmp gen lda periodl * low byte of the period sub hightimel * low byte of the hightime sta lowtimel * low byte of the lowtime lda periodh * high byte of the period sbc hightimeh * high byte of the hightime sta lowtimeh * high byte of the lowtime rts * increase the high time (duty cycle) of the pulse train incpw lda hightimel add #$01 * increment pulse width by 2 m s sta hightimel lda hightimeh adc #$0 sta hightimeh rts * decrease the high time (duty cycle) of the pulse train decpw lda hightimel sub #$01 * decrement pulse width by 2 m s sta hightimel lda hightimeh sbc #$0 sta hightimeh jsr gen rts * increase the period (decrease frequency) of the pulse train incper lda periodl add #$05 * increment period by 10 m s sta periodl lda periodh adc #$0 * adjust high byte of period if carry sta periodh jsr gen rts * decrease the period (increase frequency) of the pulse train decper lda periodl sub #$05 * decrement period by 10 m s sta periodl lda periodh sbc #$0 * adjust high byte of period if borrow sta periodh jsr gen rts timer * interrupt service routine for tcmp lda tsr * clear ocf flag in tsr lda tcmpl brset 0,tcr,addhigh * high or low pulse time needed? addlow bset 0,tcr * add low time to the pulse train lda lowtimel add tcmpl tax lda tcmph adc lowtimeh sta tcmph stx tcmpl rti addhigh bclr 0,tcr * add high time to the pulse train lda hightimel add tcmpl tax lda tcmph adc hightimeh sta tcmph stx tcmpl rti f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3374 motorola sensor device data www.motorola.com/semiconductors additional notes this type of a/d conversion method (one type of a/d conversion) inherently takes a finite period of time to digitize the signal (incrementing the pulse train's high time while polling the general i/o pin); however, for most sensor applications the physical phenomenon being measured does not change quickly (<1 ms) enough to warrant an ultrafast a/d conversion process. an additional advantage of this design is that the measurement process may be performed only as necessary, keeping the cpu processing time and overhead minimal. if an input capture timer channel (tcap) is available, it may be configured to detect the logiclevel one to logiclevel zero transition of the comparator's output. when the edge transition occurs, an interrupt service routine is executed that stores the pulse train's high times, calculates the current pressure, etc. this is typically more convenient and eliminates the need to poll a general i/o pin every time the pulse train's high time is incremented (interrupt subroutine is executed only when the edge transition occurs). summary shown above is a minimal component design that can convert an analog sensor's output into a digital output. each major subsystem (sensor, amplifier, integrator, comparator, and microcontroller) is explained in detail simultaneously with a design example. next the system operation is discussed including how it works and how to design a desired system resolution. finally a flow chart for measuring and calibrating the sensor's output is presented. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3375 motorola sensor device data www.motorola.com/semiconductors prepared by ador reodique motorola sensor systems and applications engineering introduction this application note describes how to implement an auto zero function when using a motorola integrated pressure sen- sor with a microcontroller and an analog to digital converter (mcu and an a/d). autozero is a compensation technique based on sampling the offset of the sensor at reference pres- sure (atmospheric pressure is a zero reference for a gauge measurement) in order to correct the sensor output for long term offset drift or variation. sources of offset errors are due to device to device offset vari- ation (trim errors), mechanical stresses (mounting stresses), shifts due to temperature and aging. performing autozero will greatly reduce these errors. the amount of error correction is limited by the resolution of the a/d. in pressure sensing applications where a zeropressure reference condition can exist, autozero can be implemented easily when an integrated pressure sensor is interfaced to an mcu. effects of offset errors figure 1 illustrates the transfer function of an integrated pressure sensor. it is expressed by the linear function: v out =v off + [(v fso v off )/(p max p ref )]*p =v off + s*p. here, v out is the voltage output of the sensor, v fso is the fullscale output, v off is the offset, p max is the maximum pressure and p ref is the reference pressure. note that (v fso v off /p max p ref ) can be thought of as the slope of the line and v off as they yintercept. the slope is also referred to as the sensitivity, s, of the sensor. figure 1. definition of span, fullscale output, offset and sensitivity sensor output v fso v off p ref p max pressure span s a twopoint pressure calibration can be performed to accurately determine the sensitivity and get rid of the offset calibration errors altogether. however, this can be very expensive in a high volume production due to extra time and labor involved. the system designer therefore designs a pressure sensor system by relying on the sensitivity and offset data given in the data sheet and using a linear equation to determine the pressure. using the later, the sensed pressure is easily determined by: p = (v out v off )/s. if an offset error is introduced due to device to device varia- tion, mechanical stresses, or offset shift due to temperature (the offset has a temperature coefficient or tco), those errors will show up as an error, d p, in the pressure reading: p + d p = [v out (v off + d v off )]/s. as evident in figure 2, offset errors, d v off , have the effect of moving the intercept up and down without affecting the sensitivity. we can therefore correct this error by sampling the pressure at zero reference pressure (atmosphere) and subtracting this from the sensor output. figure 2. effect of offset errors sensor output v out v fso v off p ref (atm) p max pressure d v off v p d p p autozero considerations in applications there is an important consideration when implementing autozero. in order to use this technique, a zero pressure reference condition must be known to exist in the system.

semiconductor application note rev 1 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3376 motorola sensor device data www.motorola.com/semiconductors there are a lot of applications that will lend themselves naturally to autozeroing. typical applications are those that: ? experience a zeropressure condition at system start up, ? are idle for a long time (zero pressure), take a pressure measurement then go back to idle again. for example, in a water level measurement in a washing machine application, there is a zero pressure reference condition when the water in the tub is fully pumped out. another application that is perfect for autozeroing is a beverage fill level measurement; a zero reference condition exists before the bottle is filled. hvac air flow applications can also use autozeroing; before system start up, an autozero can be initiated. in other words, it can be used in applications where a zero pressure condition can exist in order to autozero the system. an autozero command can be automated by the system or can be commanded manually. each system will have a different algorithm to command an autozero signal. for example, using the beverage fill level measurement as an example, the system will auto zero the sensor before the bottle is filled. implementation of autozero with a microcontroller autozero can be implemented easily when the integrated sensor is interfaced to a microcontroller. the autozero algorithm is listed below: 1. sample the sensor output when a known zero refer- ence is applied to the sensor (atmospheric pressure is a zero reference for gauge type measurement). store current zero pressure offset as czpo. 2. sample the sensor output at the current applied pressure. call this sp. 3. subtract the stored offset correction, czpo, from sp. the pressure being measured is simply calculated as: p meas = (sp czpo)/s. note that the equation is simply a straight line equation, where s is the sensitivity of the sensor. the autozero algorithm is shown graphically in figure 3. figure 3. flowchart of the autozero algorithm start sample current zero offset, czpo sample current pressure, sp p meas cp czpo s calculate pressure measure again autozero command received end f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3377 motorola sensor device data www.motorola.com/semiconductors improvement on offset error in the following calculations, we will illustrate how autozero will improve the offset error contribution. we will use the mpxv4006g interfaced to an 8bit a/d as an example. when autozero is performed, the offset errors are reduced and the resulting offset errors are replaced with the error (due to resolution) of the a/d. we can categorize the offset error contributions into temperature and calibration errors. temperature coefficient of offset error the offset error due to temperature is due to temperature coefficient of offset, or tco. this parameter is the rate of change of the offset when the sensor is subject to temperature. it is defined as: tco = ( d v off / d t). the mpxv4006g has a temperature coefficient of offset (normalized with the span at 25 c) of: d tco = ( d v off / d t)/v fs@25 c = 0.06% fs/ c. as an example, if the sensor is subjected to temperature range between 10 c and 60 c, the error due to tco is: d tco = (0.06% fs/c)*(60 c 10 c) = 3.0% fs. offset calibration errors even though the offset is laser trimmed, offset can shift due to packaging stresses, aging and external mechanical stresses due to mounting and orientation. this results in offset calibration error. for example, the mpxv4006g data sheet shows this as: v off min = 0.100 v, v off typical = 0.225 v and v off max = 0.430 v. we can then calculate the offset calibration error with respect to the full scale span as: d v off min,max = (v off typical v off min,max )/v fs. this results in the following offset calibration error, d v off min = 2.7% fs and d v off max = 4.5% fs. a/d error as mentioned above, we can reduce offset errors (calibration and tco) when we perform autozero. these errors are replaced with the a/d error (due to its resolution), d offset autozero = d tco + d offset = d a/d. typically, a sensor is interfaced to an 8bit a/d. with the a/d reference tied to v rh = 5 v and v rl = 0 v, the a/d can resolve 19.6 mv/bit. for example, the mxpv4006g has a sensitivity of 7.5 mv/mmh 2 0, the resolution is therefore, a/d resolution = 19.6 mv/bit)/(7.5 mv/mmh 2 0) = 2.6 mmh 2 0/bit. assuming +/ 1 lsb error, the error due to digitization and the resulting offset error is, d a/d = d offset autozero = 2.6 mmh 2 0/612 mmh 2 0 =+/ 0.4% fs. it can be seen that with increasing a/d resolution, offset errors can be further reduced. for example, with a 10bit a/d, the resulting offset error contribution is only 0.1% fs when autozero is performed. if autozero is to be performed only once and offset correction data is stored in nonvolatile memory, the tco offset error and calibration error will not be corrected if the sensor later experiences a wide temperature range or later experience an offset shift. however, if autozero is performed at the operating temperature, tco error will be compensated although subsequent offset calibration error will not be compensated. it is therefore best to autozero as often as possible in order to dynamically compensate the system for offset errors. conclusion autozero can be used to reduce offset errors in a sensor system. this technique can easily be implemented when an integrated pressure sensor is interfaced to an a/d and a microcontroller. with a few lines of code, the offset errors are effectively reduced; the resulting offset error reduction is limited only by the resolution of the a/d. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3378 motorola sensor device data www.motorola.com/semiconductors

prepared by ador reodique, sensor and systems applications engineering and warren schultz, field engineering introduction motorola integrated pressure sensors (ips) have trimmed outputs, builtin temperature compensation and an amplified singleended output which make them compatible with analog to digital converters (a/d's) on low cost microcontrol- lers. although 8bit a/d's are most common, higher resolution a/d's are becoming increasingly available. with these higher resolution a/d's, the noise that is inherent to piezoresistive bridges becomes a design consideration. the two dominant types of noise in a piezoresistive inte- grated pressure sensor are shot (white) noise and 1/f (flicker noise). shot noise is the result of nonuniform flow of carriers across a junction and is independent of temperature. the second, 1/f, results from crystal defects and also due to wafer processing. this noise is proportional to the inverse of fre- quency and is more dominant at lower frequencies 3 . noise can also come from external circuits. in a sensor sys- tem, power supply, grounding and pcb layout is important and needs special consideration. the following discussion presents simple techniques for mitigating these noise signals, and achieving excellent results with high resolution a/d converters. effects of noise in sensor system the transducer bridge produces a very small differential voltage in the millivolt range. the onchip differential amplifier amplifies, level shifts and translates this voltage to a single ended output of typically 0.2 volts to 4.7 volts. although the transducer has a mechanical response of about 500 hz, its noise output extends from 500 hz to 1 mhz. this noise is amplified and shows up at the output as depicted in figure 1. there is enough noise here to affect 1 count on an 8 bit a/d, and 4 or 5 counts on a 10 bit a/d. it is therefore important to consider filtering. filtering options are discussed as follows. figure 1. mpx5006 raw output semiconductor application note rev 1 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3379 motorola sensor device data www.motorola.com/semiconductors noise filtering techniques and considerations for mitigating the effects of this sensor noise, two general approaches are effective, low pass filtering with hardware, and low pass filtering with software. when filtering with hard- ware, a lowpass rc filter with a cutoff frequency of 650 hz is recommended. a 750 ohm resistor and a 0.33 m f capacitor have been determined to give the best results (see figure 2) since the 750 ohm series impedance is low enough for most a/d converters. figure 2. integrated pressure sensor with rc lp filter to filter out noise 1.0 f ips 0.33 f a/d 3 5 v 0.01 f 750 2 1 this filter has been tested with an mc68hc705p9 micro- controller which has a successive approximation a/d con- verter. successive approximation a/d's are generally compatible with the dc source impedance of the filter in figure 2. results are shown in figure 4. some a/d's will not work well with the source impedance of a single pole rc filter. please consult your a/d converter tech- nical data sheet if input impedance is a concern. in applica- tions where the a/d converter is sensitive to high source impedance, a buffer should be used. the integrated pressure sensor has a railtorail output swing, which dictates that a railtorail operational amplifier (op amp) should be used to avoid saturating the buffer. a mc33502 railtorail input and output op amp works well for this purpose (see figure 3). 1.0 f ips 0.33 f a/d 3 5 v 0.01 f 750 2 1 + mc33502 figure 3. use a railtorail buffer to reduce output impedance of rc filter averaging is also effective for filtering sensor noise. averag- ing is a form of low pass filtering in software. a rolling average of 8 to 64 samples will clean up most of the noise. a 10 sample average reduces the noise to about 2.5 mv peak to peak and a 64 sample average reduces the noise to about 1 mv peak to peak (see figures 5 and 6). this method is simple and requires no external compo- nents. however, it does require ram for data storage, extra computation cycles and code. in applications where the microcontroller is resource limited or pressure is changing relatively rapidly, averaging alone may not be the best solu- tion. in these situations, a combination of rc filtering and a limited number of samples gives the best results. for exam- ple, a rolling average of 4 samples combined with the rc filter in figure 2 results in a noise output on the order of 1 mv peak to peak. another important consideration is that the incremental effectiveness of averaging tends to fall off as the number of samples is increased. in other words, the signaltonoise (s/n) ratio goes up more slowly than the number of samples. to be more precise, the s/n ratio improves as the square root of the number of samples is increased. for example, increas- ing the number of samples from 10, in figure 5, to 64, in figure 6, reduced noise by a factor of 2.5. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3380 motorola sensor device data www.motorola.com/semiconductors figure 4. output after low pass filtering figure 5. output with 10 averaged samples f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3381 motorola sensor device data www.motorola.com/semiconductors figure 6. output with 64 averaged samples figure 7. filtered sensor output and averaged over 10 samples f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3382 motorola sensor device data www.motorola.com/semiconductors power supply since the sensor output is ratiometric with the supply volt- age, any variation in supply voltage will also proportionally appear at the output of the sensor. the integrated pressure sensor is designed, characterized and trimmed to be powered with a 5 v +/ 5% power supply which can supply the maxi- mum 10 ma current requirement of the sensor. powering the integrated sensor at another voltage than specified is not rec- ommended because the offset, temperature coefficient of off- set (tco) and temperature coefficient of span (tcs) trim will be invalidated and will affect the sensor accuracy. from a noise point of view, adequate decoupling is impor- tant. a 0.33 m f to 1.0 m f ceramic capacitor in parallel with a 0.01 m f ceramic capacitor works well for this purpose. also, with respect to noise, it is preferable to use a linear regulator such as an mc78l05 rather than a relatively more noisy switching power supply 5 volt output. an additional consider- ation is that the power to the sensor and the a/d voltage refer- ence should be tied to the same supply. doing this takes advantage of the sensor output ratiometricity. since the a/d resolution is also ratiometric to its reference voltage, varia- tions in supply voltage will be canceled by the system. layout optimization in mixed analog and digital systems, layout is a critical part of the total design. often, getting a system to work properly depends as much on layout as on the circuit design. the fol- lowing discussion covers some general layout principles, digi- tal section layout and analog section layout. general principles: there are several general layout principles that are impor- tant in mixed systems. they can be described as five rules: rule 1: minimize loop areas. this is a general principle that applies to both analog and digital circuits. loops are antennas. at noise sensitive inputs, the area enclosed by an incoming signal path and its return is proportional to the amount of noise picked up by the input. at digital output ports, the amount of noise that is radiated is also proportional to loop area. rule 2: cancel fields by running equal currents that flow in opposite directions as close as possible to each other. if two equal currents flow in opposite directions, the resulting electromagnetic fields will cancel as the two currents are brought infinitely close together. in printed circuit board layout, this situation can be approximated by running signals and their returns along the same path but on different layers. field cancellation is not perfect due to the finite physical sepa- ration, but is sufficient to warrant serious attention in critical paths. looked at from a different perspective, this is another way of looking at rule # 1, i.e., minimize loop areas. rule 3: on traces that carry high speed signals avoid 90 degree angles, including ato connections. if you think of high speed signals in terms of wavefronts moving down a trace, the reason for avoiding 90 degree angles is simple. to a high speed wavefront, a 90 degree angle is a discontinuity that produces unwanted reflections. from a practical point of view, 90 degree turns on a single trace are easy to avoid by using two 45 degree angles or a curve. where two traces come together to form a ato connection, adding some material to cut across the right angles accomplishes the same thing. rule 4: connect signal circuit grounds to power grounds at only one point. the reason for this constraint is that transient voltage drops along the power grounds can be substantial, due to high values of di/dt flowing through finite in- ductance. if signal processing circuit returns are connected to power ground at multiple points, then these transients will show up as return voltage differences at different points in the signal processing circuitry. since signal processing circuitry seldom has the noise immunity to handle power ground tran- sients, it is generally necessary to tie signal ground to power ground at only one point. rule 5: use ground planes selectively. although ground planes are highly beneficial when used with digital circuitry, in the analog world they are better used selectively. a single ground plane on an analog board puts parasitic capacitance in places where it is not desired, such as at the inverting inputs of op amps. ground planes also limit efforts to take advantage of field cancellation, since the return is distributed. analog layout in analog systems, both minimizing loop areas and field cancellation are useful design techniques. field cancellation is applicable to power and ground traces, where currents are equal and opposite. running these two traces directly over each other provides field cancellation for unwanted noise, and minimum loop area. figure 8 illustrates the difference between a power supply decoupling loop that has been routed correctly and one that has not. in this figure, the circles represent pads, the sche- matic symbols show the components that are connected to the pads, and the routing layers are shown as dark lines (top trace) or grey lines (bottom trace). note that by routing the two traces one over the other that the critical loop area is mini- mized. in addition, it is important to keep decoupling capaci- tors close to active devices such as mpx5000series sensors and operational amplifiers. as a rule of thumb, when 50 mil ground and vcc traces are used, it is not advisable to have more than 1 inch between a decoupling capacitor and the active device that it is intended to be decoupled. figure 8. minimizing loop areas sensor sensor recommended avoid +5 v gnd +5 v gnd top trace bot trace f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3383 motorola sensor device data www.motorola.com/semiconductors for similar reasons it is desirable to run sensor output sig- nals and their return traces as close to each other as pos- sible. minimizing this loop area will minimize the amount of external noise that is picked up by making electrical connec- tions to the sensor. digital layout the primary layout issue with digital circuits is ground partitioning. a good place to start is with the architecture that is shown in figure 9. this architecture has several key attrib- utes. analog ground and digital ground are both separate and distinct from each other, and come together at only one point. for analog ground it is preferable to make the one point as close as possible to the analog to digital converter's ground reference (v refl ). the power source ground con- nection should be as close as possible to the microcontrol- ler's power supply return (v ss ). note also that the path from v refl to v ss is isolated from the rest of digital ground until it approaches v ss . digital ground/ground plane power ground sensor/analog ground v refl v ss figure 9. ground partitioning in addition to grounding, the digital portion of a system benefits from attention to avoiding 90 degree angles, since there are generally a lot of high speed signals on the digital portion of the board. routing with 45 degree angles or curves minimizes unwanted reflections, which increases noise immu- nity. single traces are easy, two forty five degree angles or a curve easily accomplish a 90 degree turn. it is just as important to avoid 90 degree angles in t connections. figure 10 illus- trates correct versus incorrect routing for both cases. figure 10. 90 degree angles single trace avoid good practice tconnection avoid good practice conclusion piezoresistive pressure sensors produce small amounts of noise that can easily be filtered out with several methods. these methods are low pass filtering with an rc filter, averag- ing or a combination of both which can be implemented with minimal hardware cost. in a mixed sensor system, noise can be further reduced by following recommended power supply, grounding and layout techniques. references [1] an1626 noise management in motor drives, warren schultz, motorola, inc. [2] noise reduction techniques in electronic systems 2nd edition, henry w. ott, john wiley & sons. [3] noise: comparing integrated pressure sensors and op amps, ira basket, motorola sensor products division internal paper. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3384 motorola sensor device data www.motorola.com/semiconductors
prepared by: warren schultz pspice models for uncompensated, mpx2000 series, and mpx5000 series pressure sensors are presented here. these models use compound coefficients to improve modeling of temperature dependent behavior. the discussion begins with an overview of how the models are structured, and is followed by an explanation of compound coefficients. the emphasis is on how to use these models to estimate sensor performance. they can be found electronically on a disk included in asb200 motorola sensor development controller kits, and on the web at: http://www.motsps.com/home2/models/bin/sensor2.html model structure models for all three sensors series share a common structure. they are complete models set up to run as is. to obtain output voltage versus pressure, it is only necessary to run the model and display v(2,4) or v(1,0). v(2,4) gives the output voltage for uncompensated and mpx2000 series sensors. v(1,0) applies to mpx5000 sensors. in both cases, v(2,4) and v(1,0) correspond to the pin numbers where output voltage would be, if probed on an actual part. these models are divided into five sections to facilitate ease of use. they are: ? input parameters ? linear to compound conversion ? model coefficients ? transducer ? stimulus each of these sections is described in the following discussion. input parameters this section contains input parameters that describe measurable sensor characteristics. inputs such as full scale pressure (fsp), full scale span (fss) offset voltage (voffset), and temperature coefficient of offset voltage (tcos) are made here. characteristics that are specific to the transducer, such as bridge impedance (rbridge), temperature coefficient of bridge resistance (tcrb), and temperature coefficient of span (tcsp) are also listed here. parameters such as voffset that set an output value for the sensor are used to calculate resistance values that produce those outputs. for example, if you input 100 mv of offset voltage and a 10 m v/degree temperature coefficient of offset voltage, the model will calculate the bridge resistance values necessary to produce 100 mv of offset voltage and a 10 m v/degree temperature coefficient. in the mpx2000 and mpx5000 models, temperature coefficient of span (tcsp) is handled differently than the other parameters. the nonlinear behavior of span over temperature is calculated from the interaction of the transducer's temperature coefficient of span (tcsp), the transducer's temperature coefficient of resistance (tcrb), and the effects of inserting fixed resistance, rtcspan, in series with the bridge. the result is a temperature coefficient of span that closely resembles the real thing, but is not directly controlled by the user. linear to compound conversion the compound coefficients used in these models are from equations of the form: (1) r(temp) = r 25 (1 tcr) (temp 25) where r 25 is resistance at 25 degrees celsius , tcr is temperature coefficient of resistance, temp is an abbreviation for temperature in degrees celsius, and r(temp) is the function resistance versus temperature. the tcr (temperature coefficient of resistance) in equation (1) is a different number than a temperature coefficient that is stated in linear terms. the three statements in this section convert linear coefficients to the compound values that the models need. this conversion is based upon a 100 degree difference between the two points at which the linear coefficients have been measured. model coefficients in this section most of the calculation is performed. values for the transducer bridge resistors are determined from pressure, temperature, offset, temperature coefficient of offset, span, temperature coefficient of span, and temperature coefficient of resistance inputs. a series of parameter statements are used, as much as is practical, to do calculations that will fit in an 80 character line without wraparounds. these calculations use pspice's .parameter function, making the models specific to pspice. parameters are described as follows: kp e pressure constant; translates pressure into a bridge resistance multiplier ko e offset constant; offset component of bridge resistance dt e delta temperature; temperature 25 degrees celsius ktco e temperature coefficient of offset constant; trans- lates temperature coefficient of offset into bridge resistance
semiconductor application note rev 1 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3385 motorola sensor device data www.motorola.com/semiconductors tcr e temperature coefficient of bridge resistance; shaped by a table that accounts for cold temperature nonlinearity's tcr2 e temperature coefficient of contact resistance; shaped by a table that accounts for cold temperature nonlinearity's tcs e temperature coefficient of span; shaped by a table that accounts for cold temperature nonlinearity's rph e bridge resistance (rs1 and rs3) modified by pressure and temperature roh e offset component of bridge resistors rs1 and rs3 rpl e bridge resistance (rs2 and rs4) modified by pressure and temperature rol e offset component of bridge resistors rs2 and rs4 kb e bias constant; adjusts kp for bias voltage effects of span compensation network (mpx2000 and mpx5000 series sensors) kbt e bias constant; adjusts ko for bias voltage effects of span compensation network (mpx2000 and mpx5000 series sensors) gain e instrumentation amplifier gain; differential gain (mpx5000 series) roff e offset resistance; determines value of rs13 (mpx5000 series) after these calculations are made, the final bridge resis- tance calculation is performed in the circuit section. the value for bridge resistors rs1 and rs3 is rph + roh. bridge resis- tors rs2 and rs4 are equal to rplrol. circuit three circuits are used to model the three sensor families, one each for the uncompensated series, mpx2000 series, and mpx5000 series sensors. schematics that are derived from the circuit netlists are shown in figures 1, 2, and 3. they are discussed beginning with the uncompensated series, which is the least complex. uncompensated series: the uncompensated series sensors (mpx10, mpx50, and mpx100) are modeled as wheatstone bridges. in the configu- ration that is shown in figure 1, resistors rs2 and rs4 decrease in value as pressure is applied. similarly, rs1 and rs3 increase in value as pressure is applied. resistors rs5 and rs7 are contact resistors. they represent real physical resistors that are used to make contact to the bridge. resistors rs6 and rs8 are included to satisfy pspice's requirement for no floating nodes. that's it. the netlist in this model is quite simple. the hard part is calculating the values for rs1, rs2, rs3, and rs4. figure 1. mpx10 and 100 pspice compound coefficient model 3 0 2 4 5 1 ** ** ** ** * * notes: * temperature sensitive * * temperature & pressure sensitive rs4 475 rs1 475 rs2 475 rs3 475 rs8 1000meg rs7 675 rs5 750 rs6 1000meg f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3386 motorola sensor device data www.motorola.com/semiconductors mpx2000 series: the mpx2000 series sensors (mpx2010, mpx2050, mpx2100, and mpx2200) add span compensation and trim resistors to the uncompensated model. these resistors are shown in figure 2 as rs9, rs11, and rs10. the temperature coefficient of resistance (tcr) for the bridge resistors works against fixed resistors rs9 and rs11 to produce a bias to the bridge that increases with temperature. this increasing bias compensates for the temperature coefficient of span, which is negative. resistor rs12 is also added to the uncompensated model. it represents additional impedance that is associated with the mpx2000 series sensors' offset trim network. offset perfor- mance is modeled behaviorally. inputs for offset (voffset) and temperature coefficient of offset (tcos) are translated into bridge resistance values that produce the specified per- formance. this behavioral approach was chosen in order to make it easy to plug in different values for voffset and tcos. figure 2. mpx2000 series pspice compound coefficient model 6 0 2 4 51 3 7 8 ** ** ** ** * * notes: * temperature sensitive * * temperature & pressure sensitive rs11 rs4 rs1 rs2 rs3 rs9 rs8 rs7 rs12 rs5 rs6 rs10 mpx5000 series: the mpx5000 series sensors (mpx5010, mpx5050, mpx5100, mpx5700, and mpx5999) add an instrumentation amplifier to the mpx2000 series model. this amplifier is shown in figure 3. it consists of operational amplifiers es1, es2, es3, and es4. amplifiers es1, es2 and es3 are mod- eled as voltage controlled voltage sources with gains of 100,000. offset voltage, input bias current effects, etc. are tak- en into account with the values that are used to determine off- set voltage and t emperature coefficient of the sensor bridge. amplifier es4 m odels saturation voltage. its output follows the output of es3 with saturation limits at 75 millivolts and 4.9 volts. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3387 motorola sensor device data www.motorola.com/semiconductors figure 3. mpx5000 series pspice compound coefficient model 6 5 14 3 7 ** ** ** ** ** notes: * temperature sensitive * * temperature & pressure sensitive 0 8 11 13 12 10 9 2 4 1 rs2 350 rs3 350 rs7 675 rs10 rs9 1350 rs6 1000meg rs1 350 rs4 350 rs5 750 rs11 1k rs8 1000meg rs17 112k rs16 500 v(1,0) rs13 265.5 rs12 10k es3 g=100,000 + es1 g=100,000 + es2 g=100,000 + rs14 112k rs15 500 es4 + stimulus the last section of these models is labeled stimulus. bias voltage, pressure, and temperature are applied here. nominal bias voltage (vcc) is 3.0 volts for uncompensated sensors, 10.0 volts for mpx2000 sensors, and 5.0 volts for mpx5000 sensors. pressure is selected on the second line. it is effective when the * on line 4 is removed to command a temperature sweep. line 3 calls for a sweep of pressure and temperature. an * placed in front of line 3 allows the temperature sweep on line 4 to be selected. compound coefficients applying temperature coefficients to variables such as resistance is an essential part of modeling. the linear approach, that is usually used, is based upon the assumption that changes are small, and can be modeled with a linear approximation. using temperature coefficient of resistance as (tcr) as an example, the linear expression takes the form: (2) r(temp) = r 25 (1 tcr(temp 25)) provided that the tcr in equation (2) is 100 parts per million per degree celsius or less this approach works quite well. with sensor tcr's of several thousand parts per million per degree celsius, however, the small change assumption does not hold. to accurately model changes of this magnitude, the mathematical expression has to describe a physical process where a unit change in temperature produces a constant per- centage change in resistance. for example, a 1% per degree tcr applied to a 1 k ohm resistor should add 10 ohms to the resistor's value going from 25 to 26 degrees. at 70 degrees, where the resistor has increased to 2006 ohms, going from 70 to 71 degrees should add 20.06 ohms to its value. the error in the linear expression comes from that fact that it adds 10 ohms to the resistor's value at all temperatures. a physical process whereby a unit change in temperature produces a constant percentage change in resistance is easi- ly modeled by borrowing an expression from finance. com- pound interest is a direct analog of temperature coefficients. with compound interest, a unit change in time produces a constant percentage change in the value of a financial instru- ment. it can be described by the expression: (3) future value = present value (1 i) n where i is the interest rate and n is the number of periods. substituting r 25 for present value, r(temp) for future value, tcr for i, and (temp 25) for n yields: (4) r(temp) = r 25 (1 tcr) (temp 25) equation (4) works quite well, provided that tcr is constant over temperature. when modeling semiconductor resistors, it is also necessary to account for variable tcr's. at cold, the tcr for p type resistors changes with temperature. these changes are modeled using table functions that have 3 val- ues for tcr. results of this modeling technique versus actual measurements and a linear model are summarized in table 1. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3388 motorola sensor device data www.motorola.com/semiconductors table 1. actual versus modeled r(temp) temp measured r(temp) compound model linear model 40 406 406 372 25 418 418 395 0 445 445 434 25 474 474 474 50 509 508 513 75 545 545 552 100 585 584 592 125 627 626 632 150 671 671 671 in table 1, 25 and 150 degree celsius data points were used to determine both linear and compound temperature coeffi- cients. therefore, measured values, linear model values and compound model values all match at these two temperatures. at other temperatures, the linear model exhibits errors that are significant when modeling piezoresistive pressure sensors. the compound model, however, tracks with measured values to within 1 ohm out of 500 ohms. examples two examples of what the model outputs look like are shown in figures 4 and 5. figure 4 shows a sweep of pressure versus output voltage (v out ) at 0, 25, and 85 degrees celsius, for an mpx2010 sensor. it has the expected 0 to 25 mv output voltage, given a 0 to 10 kpa pressure input. at these three temperatures, compensation is sufficiently good that all three plots look like the same straight line. figure 4. mpx2010 v out versus pressure and temperature to produce the plot in figure 4, the stimulus section is set up as follows, and v(2,4) is probed. ***************************stimulus**************************** vcc 6 0 dc=10; dc bias from pin 3 to pin 1 .param pressure=0; input pressure (kpa) .dc param pressure 0_kpa 10_kpa .5_kpa temp list 0 25 85 *.dc param temp 40 125 5 * this is the default configuration with which the model is shipped. to change to a sweep of zero pressure voltage ver- sus temperature, an asterisk is placed on line 3 and removed from line 4. the stimulus section then looks as follows: ****************************stimulus*************************** vcc 6 0 dc=10; dc bias from pin 3 to pin 1 .param pressure=0; input pressure (kpa) *.dc param pressure 0_kpa 10_kpa .5_kpa temp list 0 25 85 .dc param temp 40 125 5 * again, v(2,4) is probed. the resulting output appears in figure 5. this plot shows offset versus temperature performance that is typical of mpx2000 series sensors. from 40 to 85 degrees celsius, offset compensation is quite good. above 85 degrees there is a hook in this curve, that is an important attrib- ute of the sensor's performance. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3389 motorola sensor device data www.motorola.com/semiconductors figure 5. mpx2010 offset versus temperature conclusion pspice models for uncompensated, mpx2000 series, and mpx5000 series pressure sensors are available for estimat- ing sensor performance. these models make use of the com- pounding concept that is used in finance to calculate compound interest. the resulting compound temperature coefficients do a better job than linear methods of modeling temperature dependent behavior. these models make exten- sive use of pspice's .parameter statement, and are, therefore, specific to pspice. they are intended as refer- ences for determining typical sensor performance, and are structured for easy entry of alternate assumptions. disclaimers macromodels, simulation models, or other models pro- vided by motorola, directly or indirectly, are not warranted by motorola as fully representing all of the specifications and operating characteristics of the semiconductor product to which the model relates. moreover, these models are fur- nished on an aas iso basis without support or warranty of any kind, either expressed or implied, regarding the use thereof and motorola specifically disclaims all implied warranties of merchantability and fitness of the models for any purpose. motorola does not assume any liability arising out of the application or use of the models including infringement of patents and copyrights nor does motorola convey any license under its patents and copyrights or the rights of others. motorola reserves the right to make changes without notice to any model. although macromodels can be a useful tool in evaluating device performance in various applications, they cannot model exact device performance under all conditions, nor are they intended to replace breadboarding for final verification. motorola reserves the right to make changes without further notice to any products herein. motorola makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does motorola assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liabil- ity, including without limitation consequential or incidental damages. atypicalo parameters can and do vary in different applications. all operating parameters, including atypicalso must be validated for each customer application by custom- er's technical experts. motorola does not convey any license under its patent rights nor the rights of others. motorola prod- ucts are not designed, intended, or authorized for use as com- ponents in systems intended for surgical implant into the body, or other applications intended to support or sustain life, or for any other application in which the failure of the motorola prod- uct could create a situation where personal injury or death may occur. should buyer purchase or use motorola products for any such unintended or unauthorized application, buyer shall indemnify and hold motorola and its officers, employees, sub- sidiaries, affiliates, and distributors harmless against all claims, costs, damages, and expenses, and reasonable attor- ney fees arising out of, directly or indirectly, any claim of per- sonal injury or death associated with such unintended or unauthorized use, even if such claim alleges that motorola was negligent regarding the design or manufacture of the part. motorola and (motorola logo symbol) are registered trade- marks of motorola, inc. motorola, inc. is an equal opportunity/ affirmative action employer. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3390 motorola sensor device data www.motorola.com/semiconductors prepared by ador reodique sensor and systems applications engineer introduction north american washing machines currently in production use mechanical sensors for water level measurement func- tion. these sensors are either purely mechanical pressure switch with discrete trip points or electromechanical pressure sensor with an onboard electronics for a frequency output. high efficiency machines require high performance sen- sors (accuracy, linearity, repeatability) even at lower pres- sure ranges. benchmarks indicate that these performance goals is difficult to achieve using current mechanical pres- sure sensors 1 . in europe, where energy conservation is mandated, washing machine manufacturers have started to look at electronic solu- tions where accuracy, reliability, repeatability and additional functionality is to be implemented. north american and asia pacific manufacturers are also looking for better solutions. from surveys of customer requirements, a typical vertical axis machine calls for a sensor with 600 mmh 2 o (24 a h 2 o ~ 6 kpa) sensor with a 5 % fs accuracy spec. certain appli- ances call for a lower pressure range especially in europe where horizontal axis machines are common. sensor solutions for the typical 600 mmh 2 o, 5 % fs spec, an off the shelf solution available today is the mpx10/mpx12, mxp2010 and the mpxv4006g sensor. the mpx10 (or the mpx12) is 10 kpa (40 a h 2 o) fullscale pressure range device. it is uncom- pensated for temperature and untrimmed offset and fullscale span. this means that the end user must temperature com- pensate as well as calibrate the fullscale offset and span of the device. the output of the device must be amplified using a differential amplifier (see figure 1) so it can be interfaced to an a/d and to obtain the desired range. since the mpx10/mpx12 sensors must be calibrated, the implications of this device being used in highvolume pro- duction is expensive. because the offset and fullscale out- put can vary from part to part, a twopoint calibration is required as a minimum. a two point calibration is a time con- suming procedure as well as possible modification to the pro- duction line to accommodate the calibration process. the circuitry must also accommodate for trimming, i.e., via trim- pots and/or eeprom to store the calibration data. this adds extra cost to the system. the mpx2010 is a 10kpa (40o h 2 o), temperature compen- sated, offset and fullscale output calibrated device. a differ- ential amplifier like the one shown in figure 1 should be used to amplify its output. unlike the mpx10 or mpx12, this device does not need a twopoint calibration but autozeroing can improve its performance. this procedure is easily imple- mented using the system mcu. the mpxv4006g is a fully integrated pressure sensor spe- cifically designed for appliance water level sensing applica- tion. this device has an on board amplification, temperature compensation and trimmed span. an autozero procedure should be implemented with this device (see application note an1636). because expensive and time consuming calibra- tion, temperature compensation and amplification is already implemented, this device is more suitable for high volume pro- duction. the mpxv4006g integrated sensor is guaranteed to be have an accuracy of +/3 % fs over its pressure and tem- perature range. for washing machine applications where low cost and high volume productions are involved, both the mpx2010 and mpxv4006g are recommended. both solutions can be used in current vertical axis machines where the water level in the 600 mmh 2 o or 24 a h 2 o range. in the following, a comparison is made between mpx2010 and mpxv4006g in terms of system and performance considerations to help the customer make a decision. expected accuracy of the mpx2010 system solution the mpx2010 compensated sensor has an off the shelf overall rms accuracy of +/7.2 % fs over 0 to 85 c tempera- ture range. autozeroing can improve the sensor accuracy to +/ 4.42 % fs. however, since this sensor does not have an integrated amplification, its amplifier section must be designed carefully in order to meet the target accuracy requirement. the mpx2010 compensated sensor has the following specifica- tions shown on table 1.
semiconductor application note f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3391 motorola sensor device data www.motorola.com/semiconductors table 1. mpx2010 specifications characteristic min typ max unit pressure range 0 10 kpa supply voltage 10 16 vdc supply current 6 ma full scale span 24 25 26 mv offset 1 1 mv sensitivity 25 mv/kpa linearity 1 1 %v fss pressure hysterisis 0.1 %v fss temperature hysterisis ( 40 to 125 c) 0.5 %v fss temperature effect on span 1 1 %v fss temperature effect offset (0 to 85 c) 1 1 mv input impedance 1300 2550 ohms output impedance 1400 3000 ohms response time (10% to 90%) 1 ms warmup 20 ms the sensor system errors is made up of the sensor errors, amplifier errors and a/d errors. in other words, (1) system sensor 2 amplifier 2 adresolution 2 table 2 shows the mpx2010 with the errors converted to %v fss . the expected maximum root mean squared error of the sensor is (2) sensor spancal 2 lin 2 phys 2 thys 2 tcs 2 offcal 2 tco 2 offstab 2 = +/ 7.19 % fs. with autozeroing, the offset calibration, temperature effect on offset and offset stability is reduced or eliminated, sensor spancal 2 lin 2 phys 2 thys 2 tcs 2 (3) = +/ 4.42 % fs. the sensor error is calculated using the fullscale pres- sure range of the device, 0 to 85 c temperature and 10 v excitation. in comparison with the mpxv4006g solution, the expected accuracy of the system (mpxv4006g + 8 bit a/d) with autozero is 3.1 % fs. table 2. mpx2010 span, offset and calculated maximum rms error. *this assumes that the power supply is constant. span errors (converted to %v fss ) symbol error value note unit span calibration spancal 4 %v fss linearity lin 1 %v fss pressure hysterisis phys 0.1 %v fss temperature hysterisis thys 0.5 %v fss temperature effect on span tc s 1.5 %v fss offset errors (converted to %v fss ) offset calibration offcal 4 %v fss temperature effect on offset tc o 4 %v fss offset stability offstab 0.5 %v fss calculated maximum rms errors rms error no compensation* 7.19 % fs with autozero 4.42 % fs f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3392 motorola sensor device data www.motorola.com/semiconductors amplifier selection and amplifier induced errors a differential amplifier is needed to convert the differential output of the mpx2010 sensor to a high level ground referenced (s ingleended). the classic threeop amp instru- mentation amplifier can be used. however, it requires additional components (3 opamps and possibly a split power supply). an instrumentation topology shown in figure 1 requires only a single supply and only 2 opamps and 1% resistors. figure 1. mpx2010 amplifier circuit v ref +v cc r+s2 r+s1 + r1 r2 2 3 1 r3 + r4 6 7 5 u1b v out_fs +v cc 4 3 x1 12 s+ pressure sensor s u1a the circuit uses a voltage divider r+s1 and r+s2 to provide the reference (level shift), u1a and u1b are noninverting amplifiers arranged in a differential configuration with gain resistors r1, r2, r3 and r4. note that u1b is the main gain stage and it has the most gain. it is recommended to place a 0.015 m f capacitor in it's feedback loop (in parallel with r4) to reduce noise. the amplifier output can be characterized with the equation below: (4) gain r4 r3 1 (5) voffset vref r2r1 r1r3 vscm r2r4 r1r3 1 (6) vout (s s ) gain voffset (7) where (s s ) sensor differential output sensor offset equation 4 is the differential gain of the amplifier and equation 5 is the resulting offset voltage of the amplifier. the above equations assume that the amplifier is close to ideal (high a ol , low input offset voltage and low input offset bias currents). since an ideal opamp is hard to come by, the customer should select an opamp based on cost and perfor- mance. below are some points to keep in mind when selecting an opamp and designing the amplifier circuit. note that the ratio r2*r4/r1*r3 controls the system offset as well as the common mode error of the amplifier. mis- matches in these resistors will result in an offset and common mode error which appear as offset. it is therefore recom- mended to use 1% metal film resistors to reduce these errors. also, vref source impedance should be minimized in compari- son with r1 in order to reduce common mode error. amplifier input offset and input bias currents can induce errors. for example, an input offset (vio) of the amplifier can become significant when the closedloop gain of the amplifier is increased. furthermore, there is also a temperature coeffi- cient of the input voltage offset which contribute an additional error across temperature. if the input bias current of the ampli- fier is not taken into account in the design, it can also become a source of error. a technique to reduce this error is to match the impedance the source impedance of what the opamp input pins sees. it is important to note that high performance opamps are more expensive. an mc33272 opamp has a low input offset and low input bias current which is suitable for the twoop amp amplifier design. we can see that there is a tradeoff between accuracy and cost when designing a solution with the mpx2010. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3393 motorola sensor device data www.motorola.com/semiconductors when designing a system based on the mpx2010, it is important to take into account errors due to parametric varia- tion of the sensor (i.e. offset calibration, span calibration, tcs, tco), power supply and the inherent errors of the amplification circuit. the offset and span errors greatly determines the reso- lution of the system (which adds to the system error). even though the system offset error can be nulled out by autozero- ing, these errors must be accounted for when setting the sys- tem gain (see an1556 for more details). this forces the total span of the system to be smaller, because we must reserve an extra headroom from the total span to account for amplifier and a/d variations (i.e. amp. sat. voltage, power supply varia- tion, a/d quantization error, and gain errors ). if these errors are not accounted for, it could, for example, result in non linearity errors if the sensor span or offset error causes the amplified output of the sensor to reach the saturation voltage of the amplifier. as an example, a mpx2010 sensor system is designed which has a range of 600 mmh 2 o fs range with a +/ 5 % fs rms error. the system uses a +5 v +/ 5% linear regulated power supply, a mc33272 dual opamp and a 1% resistors. table 3 shows the resulting specification and component values for the system based on mpx2010 sensor. table 3. mpx2010 sensor system values mpx2010 sensor design parameter description value units vcc reg power supply 5 v differential gain gain 433 v/v vout_fs full scale span 3.02 v vref offset reference 0.66 v parts list u1a,u1b mc33272 opamp r1 gain resistor 39.2k ohms r2 gain resistor 90.9 ohms r3 gain resistor 909 ohms r4 gain resistor 392k ohms r + s1 level shift resistor 1k ohms r + s2 level shift resistor 150 ohms x1 mpx2010 table 4. performance comparison between mpx2010 and mpxv4006g solution mpx2010 solution error (fs = 600 mmh 2 o) mpxv4006g solution error (fs = 612 mmh 2 o) error contribution +/ % fs +/ mmh 2 o +/ % fs +/ mmh 2 o max sensor error 7.19 43 3.00 18 system resolution (a/d + amplification) 1.30 8 0.80 5 system error (sensor + a/d + amplification) 7.3 44 3.10 19 system error with autozero 4.6 28 3 19 note that the error due to system resolution is higher for the mpx2010 solution (+/ 2 bit a/d accuracy). this is because the mpx2010 span is limited as discussed above. also, this accuracy assumes that the amplifier does not induce signifi- cant errors. as noted mpxv4006g sensor has better overall accuracy. the system resolution is very good because of its large span (4.6 v versus 3.0 v typical). f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3394 motorola sensor device data www.motorola.com/semiconductors summary several washing machine solutions were examined. the mpx10/12 solution can be expensive in terms of additional support circuitry and the added time and labor involved during the calibration procedure. the mpx2010 is good alternative for high volume manufacturing because is already calibrated. with this solution, however, the system amplifier design must be chosen and designed carefully in order to minimize the sys- tem error. this is a consideration when deciding to implement a high accuracy solution with the mpx2010 because the cost of the system will go up. the mpxv4006g solution is geared towards high volume manufacturing because trimming, compensation and amplifi- cation is already on board. besides the system simplicity and using less component, the resolution and overall accuracy of this solution is better than the mpx2010 solution. in some cases, less components can actually improve the reliability and manufacturability the system. references [1] benc hmark of washing machine mechanical sensor, jack rondoni, motorola internal document. [2] mec hanical sensor characterization, ador reodique, motorola internal document. [3] an 1551 low pressure sensing with the mpx2010 pressure sensor, jeff baum, motorola application note. [4] an 1636 implementing autozero for integrated pressure sensors, ador reodique, motorola application note. [5] an1556 designing sensor performance specifications for mcubased systems, eric jacobsen and jeff baum, motorola application note. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3395 motorola sensor device data www.motorola.com/semiconductors by michelle clifford applications engineer sensor products division tempe, az introduction many washing machines that are currently in production use a mechanical sensor for water level detection. mechanical sensors work with discrete trip points that enable water level detection only at those points. the purpose for this reference design is to allow the user to evaluate a pressure sensor for not only water level sensing to replace a mechanical switch, but also for water flow measurement, leak detection, and other solutions for smart appliances. this system continuously monitors water level and water flow using the temperature compensated mpxm2010gs pressure sensor in the low cost mpak package, a dual opamp, and the mc68hc908qt4, 8pin microcontroller. system design pressure sensor the motorola pressure sensor family has three levels of integration uncompensated, compensated and integrated. for this design, the mpxm2010gs compensated pressure sensor was selected because it has both temperature compensation and calibration circuitry on the silicon, allowing a simpler yet more robust system circuit design. an integrated pressure sensor, such as the mpxv5004g, is also a good choice for the design eliminating the need for the amplification circuitry. the height of most washing machine tubs is 40cm, therefore the water height range that this system will be measuring is between 040cm. this corresponds to a pressure range of 0 4 kpa. therefore, the mpxm2010gs was selected for this system. the sensor sensitivity is 2.5mv/kpa, with a fullscale span of 25mv at the supply voltage of 10 vdc. the fullscale output of the sensor changes linearly with supply voltage, so a supply voltage of 5v will return a fullscale span of 12.5 mv. (v s actual / v s spec ) x v out fullscale spec = v out fullscale (5 v/ 10 v) x 25 mv = 12.5 mv since this application will only be utilizing 40% of the pressure range, 04kpa, our maximum output voltage will be 40% of the fullscale span. v out fs x (percent fs range ) = v out max 12.5 mv x 40% = 5.0 mv the package of the pressure sensor is a ported mpak package. this allows a tube to be connected to the sensor; the tube is connected to the bottom of the tub. this isolates the sensor from direct contact with the water. the small size, and low cost are additional features that make this package a perfect fit for this application. figure 1. mpxm2010gs/gst1 case 1320a

semiconductor application note rev 0 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3396 motorola sensor device data www.motorola.com/semiconductors table 1: mpxm2010d operating characteristics (v s = 10 vdc, t a = 25 c unless otherwise noted, p1 > p2) characteristic symbol min typ max unit pressure range (1) p op 0 e 10 kpa supply voltage (2) v s e 10 16 vdc supply current i o e 6.0 e madc full scale span (3) v fss 24 25 26 mv offset (4) v off 1.0 e 1.0 mv sensitivity d v/ d p e 2.5 e mv/kpa linearity (5) e 1.0 e 1.0 %v fss amplifier selection and amplifier induced errors the sensor output needs to be amplified before being inputted directly to the microcontroller through an 8bit a/d input pin. to determine the amplification requirements, the pressure sensor output characteristics and the 05v input range for the a/d converter had to be considered. the amplification circuit uses three opamps to add an offset and convert the differential output of the mpxm2010gs sensor to a groundreferenced, singleended voltage in the range of 0 5v. the pressure sensor has a possible offset of +/ 1mv at the minimum rated pressure. to avoid a nonlinear response when a pressure sensor chosen for the system has a negative offset (voff), we have added a 5mv offset to the positive sensor output signal. this offset will remain the same regardless of the sensor output. any additional offset that the sensor or opamp introduce is compensated for by software routines that are invoked when the initial system calibration is done. to determine the gain required for the system, the maximum output voltage from the sensor for this application had to be determined. the maximum output voltage from the sensor is approximately 12.5mv with a 5v supply since the fullscale output of the sensor changes linearly with supply voltage. this system will have a maximum pressure of 4kpa at 40cm of water. at a 5v supply, we will have a maximum sensor output of 5mv at 4kpa of pressure. to amplify the maximum sensor output to 5.0v, the following gain is needed: gain = (max output needed) / (max sensor output and initial offset) = 5.0v / (.005v + .005) = 500 the gain for the system was set for 500 to avoid railing from possible offsets from the pressure sensor or the opamp. the voltage outputs from the sensor are each connected to a noninverting input of an opamp. each opamp circuit has the same resistor ratio. the amplified voltage signal from the negative sensor lead is v a . the resulting voltage is calculated as follows: v a = (1+r8/r6) * v 4 = (1+10/1000) * v 4 = (1.001) * v 4 the amplified voltage signal from the positive sensor lead is v b . this amplification adds a small gain to ensure that the positive lead, v 2 , is always greater than the voltage output from the negative sensor lead, v 4 . this ensures the linearity of the differential voltage signal. v b = (1+r7/r5) * v 2 (r7/r5) * vcc = (1+10/1000) * v 2 + (10/1000)*(5v) = (1.001) * v 2 + .005v the difference between the positive sensor voltage, v b , and the negative sensor voltage, v a is calculated and amplified with a resulting by a gain of 500. v c = (r12/r11) * (v b v a ) = (500k/1k) * (v b v a ) = 500 * (v b v a ) the output voltage, vc, is connected to a voltage follower. therefore, the resulting voltage, vc, is passed to an a/d pin of the microcontroller. the range of the a/d converter is 0 to 255 counts. however, the a/d values that the system can achieve are dependent on the maximum and minimum system output values: count = (v out v rl ) / ( v rh v rl ) x 255 where v xdcr = transducer output voltage vrh = maximum a/d voltage vlh = minimum a/d voltage count (0mm h20) = (2.5 0) / (5.0 0) x 255 = 127 count (40mm h20) = (5.0 0) / (5.0 0) x 255 = 255 total # counts = 255 127 = 127 counts. the resolution of the system is determined by the mm of water that is represented by each a/d count. as calculate above, the system has a span of 226 counts to represent water level up to and including 40cm. therefore, the resolution is: resolution = mm of water / total # counts = 400mm/127 counts = 3.1 mm per a/d count f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3397 motorola sensor device data www.motorola.com/semiconductors + + + + figure 2. amplification scheme r5 1k r7 10 r8 10 r6 1k r11 1k r9 1k r10 500k r12 500k v2 sensor v4 sensor vout vcc c5 0.1 m f 6 5 7 2 3 1 9 10 8 13 12 14 11 4 vcc v a v c v b microprocessor to provide the signal processing for pressure values, a microprocessor is needed. the mcu chosen for this application is the mc68hc908qt4. this mcu is perfect for appliance applications due to its low cost, small 8pin package, and other onchip resources. the mc68hc908qt4 provides: a 4 channel, 8bit a/d, a 16bit timer, a trimmable internal timer, and insystem flash programming. the central processing unit is based on the high performance m68hc08 cpu core and it can address 64 kbytes of memory space. the mc68hc908qt4 provides 4096 bytes of user flash and 128 bytes of random access memory (ram) for ease of software development and maintenance. there are 5 bidirectional input/output lines and one input line that are shared with other pin features. the mcu is available in 8pin as well as 16pin packages in both pdip and soic. for this application, the 8pin pdip was selected. the 8pin pdip was chosen for a small package, eventually to be designed into applications as the 8pin soic. the pdip enables the customer to reprogram the software on a programming board and retest. display depending on the quality of the display required, water level and water flow can be shown with 2 leds. if a higher quality, digital output is needed, an optional lcd interface is provided on the reference board. using a shift register to hold display data, the lcd is driven with only 3 lines outputted from the microcontroller: an enable line, a data line, and a clock signal. the two leds are multiplexed with the data line and clock signal. figure 3. multiplexed lcd circuit hc908qt4 hc164 lcd en rs rw db0 db1 db2 db3 db4 db5 db6 db7 a b clk pta4 pta3 pta5 r3 r2 1k 1k multiplexing of the microcontroller output pins allows communication of the lcd to be accomplished with 3 pins instead of 8 or 11 pins of i/o lines that are usually needed. with an 8bit shift register, we are able to manually clock in 8 bits of data. the enable line, en, is manually enabled when 8 bytes have been shifted in, telling the lcd that the data on the data bus is available to execute. the leds are used to show pressure output data, by displaying binary values that correspond to a pressure range. leak detection or waterflow speed is displayed by blinking a green led at a speed relating to the speed of water flow. the red led will display the direction of water flow. turning the red led off signifies water flowing into the tub. turning the red led on signifies water flowing out of the tub, or there is a leak. digital values for water height, rate of water flow, and calibration values are displayed if an lcd is connected to the board. other this system is designed to run on a 9v battery. it contains a 5v regulator to provide 5v to the pressure sensor, microcontroller, and lcd. the battery is mounted on the back of the board using a space saving spring battery clip. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3398 motorola sensor device data www.motorola.com/semiconductors table 2: parts list ref qty. description value vendor part no. u2 1 pressure sensor 1 motorola mpxm2010gs c1 1 vcc cap 0.1uf generic c2 1 opamp cap 0.1uf generic c3 1 shift register cap 0.1uf generic d1 1 red led generic d2 1 green led generic s2,s3 2 pushbuttons generic u1 1 quad opamp adi ad8544 u3 1 voltage regulator 5v fairchild lm78l05ach u4 1 microcontroller 8pin motorola mc68hc908qt4 r1 1 w resister 22k generic r2 1 w resister 2.4k generic r3,r6 2 w resister 1.2m generic r4,r5 2 w resister 1.5k generic r7,r8 2 w resister 10k generic r9,r10 2 w resister 1k generic u6 1 lcd (optional) 16x2 seiko l168200j000 u5 1 shift register texas instruments 74hc164 smart washer software this application note describes the first software version that was available. however updated software versions may be available with further functionality and menu selections. software user instructions when the system is turned on or reset, the microcontroller will flash the select led and display the program title on the lcd for 5 seconds or until the select (sel) button is pushed. then the menu screen is displayed. using the select (sel) pushbutton, the user can scroll through the menu options for a software program. to run the water level program, use the select button to highlight the awater levelo option, then press the enter (ent) pushbutton. the water level program will display current water level, the rate of flow, a message if the container is afillingo, aemptyingo, afullo, or aemptyo, and a scrolling graphical history displaying data points representing the past forty level readings. the water level is displayed by retrieving the digital voltage from the internal a/d converter. this voltage is converted to pressure in millimeters of water and then displayed on the lcd. calibration and calibration software to calibrate the system, a twopoint calibration is performed. the sensor will take a calibration point at 0mm and at 40mm of water. hold down both the sel and ent buttons on system powerup to enter calibration mode. at this point, the calibration menu will be displayed with the previously sampled offset voltage. to recalibrate the system, expose the sensor to atmospheric pressure and press the sel button (pb1). at this point, the zero offset voltage will be sampled and saved to a location in the microcontroller memory. to obtain the second calibration point, place the end of the plastic tube from the pressure sensor to the bottom of a container holding 40mm of water. then press the ent button (pb2). the voltage output will be sampled, averaged and saved to a location in memory. to exit the calibration mode, press the sel (pb1) button. figure 4. water level system setup for demonstration 40 cm 35 cm 30 cm 25 cm 20 cm 15 cm 10 cm 5 cm converting pressure to water level hydrostatic pressure that we are measuring is the pressure at the bottom of a column of fluid caused by the weight of the fluid and the pressure of the air above the fluid. therefore, the hydrostatic pressure depends on the air pressure, the fluid density and the height of the column of fluid. p= pa + r g d h where p = pressure pa = pressure r = mass density of fluid g = 9.8066 m/s^2 h = height of fluid column to calculate the water height, we can use the measured pressure with the following equation, assuming the atmospheric pressure is already compensated for by the selection of the pressure sensor being gauge: d h = p \ r g f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3399 motorola sensor device data www.motorola.com/semiconductors software function descriptions main function the main function calls an initialization function aallinito, calls a warmup function awarmupo to allow extra time for the lcd to initialize, then checks if buttons pb1 and pb2 are being pressed. if they are both pressed, then it calls a calibration function acalibo. if they are not both pressed, then it enters the main function loop. the main loop displays the menu, moves the cursor when the pb1 is pressed and enters the function corresponding to the highlighted menu option when pb2 is pressed. calibration function the calibration function is used to obtain two calibration points. the first calibration point is taken when the head tube is not placed in water to obtain the pressure for 0mm of water. the second calibration point is obtained when the head tube is placed at the bottom of a container with a height of 160mm. when the calibration function starts, a message appears displaying the a/d values for the corresponding calibration points currently stored in the flash. to program new calibration points, the user must press pb1 to take 256 a/d readings at 0mm of water. the average is calculated and stored in a page of flash. then the user has the option to press pb1 to exit the calibration function or obtain the second calibration point. to obtain the second calibration point, the head tube should be placed in 160mm of water and then the user should press pb2 to take 256 a/d readings. the average is taken and stored in a page of flash. once the two readings have been taken, averaged, and stored in the flash, a message displays the two a/d values that were stored. level function the level function will initialize the graphics characters. once this is complete, it will continue looping to obtain an average a/d reading and display the water level, the water flow, and a graphical history until the user presses and holds both pb1 and pb2 to return to the main function. the function first clears the 40 pressure readings that it will be updating for the graphical history. it then enters the loop which first displays 8 special characters, each containing 5 data points of water level history. the function aadcbytao is called to obtain the current averaged a/d value. the function alfnxo is called to convert the a/d value to a water level, which is then compared to the calibration points, the maximum and minimum points, to determine if the container is full or empty. if true, then it displays the corresponding message. the current water level is compared to the previous read and displays the message afillingo if it has increased, aemptyingo if it has decreased, and asteadyo if it has not changed. the water level calculation has to be converted to decimal in order to display it in the lcd. to convert the water level calculation to decimal, the value is continually divided with the remainder displayed to the screen for each decimal place. to display the rate of water flow, the sign of the value is first determined. if the value is negative, the one's complement is taken, a negative sign is displayed, and then the value is continually divided to display each decimal place. if the number is positive, a plus sign is displayed to maintain the display alignment and the value is continually divided to display each decimal place. the most complicated part of this function is updating the graphics history display. the characters for the 16x2 lcd that were chosen for this reference design are 8x5 pixels by default. therefore, each special character that is created will be able to display 5 water level readings. since the height of the special character is 8 pixel, each vertical pixel position will represent a water level in increments of 20mm. resolution = (h1 h0) / d where h1 and h2 are the maximum and minimum water levels respectively and d is the possible datapoints available per character. resolution = (160mm 0mm) / 8 = 20mm / data point. the graphical history is displayed using the 8 special characters. to update the graphics, all the characters have to be updated. the characters are updated by first positioning a pixel for the most recent water level reading in the first column of the first character. then the four right columns of the first character are shifted to the right. the pixel in the last column of that character is then carried to the first column of the next character. this column shifting is continued until all 40 data points have been updated in the 8 special characters. lfnx function the lfnx function calculates the water level from the current a/d pressure reading. the a/d pressure value is stored in register a before this function is called. using the a/d value and the calibration values stored in the flash, the water level is calculated from the following function: rbra: = (nx n1) * 160 / (n2 n1), where nx is the current a/d value n1 is the a/d value at 0mm h20 n2 is the a/d value at 160mm h20 to simplify the calculation, the multiplication is done first. then the function andivdo is called to divide the values. ndivd function the andivdo function performs a division by counting successive subtractions of the denominator from the numerator to determine the quotient. the denominator is subtracted from the numerator until the result is zero. if there is an overflow, the remainder from the last subtraction is the remainder of the division. wrflash and ersflsh functions the awrflasho and aersflsho functions are used to write to and erase values from the flash. for more information regarding flash functionality, refer to section 4. flash memory from the mc68hc908qy4/d databook. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3400 motorola sensor device data www.motorola.com/semiconductors allinit function the allinit function disables the cop for this version of software, sets the data direction bits, and disables the data to the lcd and turns off the lcd enable line. it also sets up the microcontroller's internal clock to half the speed of the bus clock. see section 15, computer operating properly, of the mc68908qt4 datasheet for information on utilizing the cop module to help software recover from runaway code. warmup function the warmup function alternates the blinking of the two leds ten times. this gives the lcd some time to warm up. then the function awarmupo calls the lcd initialization function, alcdinito. bintasc function the abinasco function converts a binary value to its ascii representation. a/d functions the a/d functions are used to input the amplified voltage from the pressure sensor from channel 0 of the a/d converter. the function aadcbytio will set the a/d control register, wait for the a/d reading and load the data from the a/d data register into the accumulator. the function aadcbytao is used to obtain an averaged a/d reading by calling aadcbytio 256 times and returning the resulting average in the accumulator. lcd functions the lcd hardware is set up for multiplexing 3 pins from the microcontroller using an 8bit shift register. channels 3, 4, and 5 are used on port a for the lcd enable (e), the lcd reset (rs), and the shift register clock bit, respectively. the clock bit is used to manually clock data from channel 4 into the 8bit shift register. this is the same line as the lcd rs bit because the msb of the data is low for a command and high for data. the rs bit prepares the lcd for instructions or data with the same bit convention. when the 8 bits of data are available on the output pins of the shift register, the lcd enable (e) is toggled to receive the data. the lcd functions consist of an initialization function alcdinito which is used once when the system is started and five output functions. the functions alcdcmdoo and alcdchroo both send a byte of data. the function ashiftao is called by both alcdcmdoo and alcdchroo to manually shift 8 bits of data into the shift register. the function alcdniboo converts the data to binary before displaying. the alcdbytoo displays a byte of data by calling alcdniboo for each nibble of data. the function alcdstroo enables strings to be easily added to the software for display. the function accepts a commadelimited string of data consisting of 12 commands for clearing the screen and positioning the cursor. it then continues to output characters from the string until the a@o symbol is found, signally the end of the string. conclusion the water level reference design uses a mpxm2010gs pressure sensor in the low cost mpak package, the low cost, 8pin microcontroller, and a quad opamp to amplify the sensor output voltage. this system uses very few components, reducing the overall system cost. this allows for a solution to compete with a mechanical switch for water level detection but also offer additional applications such as monitoring water flow for leak detection, and the other applications for smart washing machines. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3401 motorola sensor device data www.motorola.com/semiconductors software listing ;nitrowater 2.0 15nov02 ; ; ;water level reference design ;**************************** ; uses nitron (mc68hc08qc4) and mpak (mpxm2010gs) ; calib: 2point pressure calibration (0mm and 160mm) ; level: displays water level, flow, and graphics ; units: displays a/d value, calib max/min values ;__________________________________________________________ ram equ $0080 ;memory pointers rom equ $ee00 vectors equ $ffde ;__________________________________________________________ porta equ $00 ;registers ddra equ $04 config2 equ $1e config1 equ $1f tsc equ $20 tmodh equ $23 icgcr equ $36 adscr equ $3c adr equ $3e adiclk equ $3f flcr equ $fe08 flbpr equ $ffbe ;__________________________________________________________ org $fd00 ;flash variables n1 db $96 ;1st calibration pt. = 0mm org $fd40 n2 db $f6 ;2nd calibration pt. = 160mm org $fd80 ;__________________________________________________________ org vectors dw cold ;adc dw cold ;keyboard dw cold ;not used dw cold ;not used dw cold ;not used dw cold ;not used dw cold ;not used dw cold ;not used dw cold ;not used dw cold ;not used dw cold ;tim overflow dw cold ;tim channel 1 dw cold ;tim channel 0 dw cold ;not used dw cold ;irq dw cold ;swi dw cold ;reset ($fffe) ;__________________________________________________________ org ram bb ds 1 flshadr ds 2 flshbyt ds 1 memsp ds 2 mem03 ds 2 cnt ds 1 lgfx ds 1 weath ds 1 ram0 ds 1 nc ds 1 nb ds 1 na ds 1 dc ds 1 db ds 1 da ds 1 mb ds 1 ma ds 1 ob ds 1 oa ds 1 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3402 motorola sensor device data www.motorola.com/semiconductors rb ds 1 ra ds 1 p0c ds 1 p0b ds 1 p0a ds 1 nptr ds 1 ramfree ds 80 ;used both for running ram version of wrflash & storing 40 readings ;__________________________________________________________ ;__________________________________________________________ org rom cold: rsp jsr allinit ;general initialization jsr warmup ;give lcd extra time to initialize brset 1,porta,nocalib brset 2,porta,nocalib jmp calib ;do calibration if sel & ent at reset nocalib: ldhx #msg01 ;otherwise skip and show welcome messages jsr lcdstro ;oreference designo msg jsr del1s ldhx #msg01a ;owater levelo msg jsr lcdstro jsr del1s menu: ldhx #msg01b jsr lcdstro clr ra ;menu choice=0 to begin with lda #$0d jsr lcdcmdo ;blink cursor on menu choice luke: ldx ra ;get current menu choice clrh lda menupos,x ;and look up corresponding lcd address jsr lcdcmdo warm: brclr 1,porta,pb1 ;wait for sel brclr 2,porta,pb2 ;or for ent bclr 4,porta bset 5,porta ;toggle leds jsr del100ms ;delay bset 4,porta bclr 5,porta ;toggle again: sel ***or*** ent jsr del100ms ;delay and repeat until sel or ent bra warm pb1: inc ra ;***sel*** toggles menu choices lda ra cmp #$02 ;menu choices are $00 and $01 blt pb1ok cmp #$03 bgt menureset ; shift up and display 3 menu2: ldhx #msg01c jsr lcdstro menureset: clr ra ;back to $00 when all others have been offered pb1ok: bclr 4,porta bclr 5,porta ;leds off jsr del100ms ;wait a little bit brclr 1,porta,pb1ok ;make sure they let go of sel bra luke pb2: bclr 4,porta ;***ent*** confirms menu choice bclr 5,porta ;leds off lda ra ;get menu choice cmpa #$00 bne skip00 jmp level ;do ===level=== if choice=$00 skip00: cmpa #$01 bne skip01 jmp units ;do ===units=== if choice=$01 skip01: cmpa #$02 bne skip02 ;do ==mancalib= if choice=$02 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3403 motorola sensor device data www.motorola.com/semiconductors jmp mancalib skip02: jmp test ;__________________________________________________________ ;__________________________________________________________ calib: ldhx #msg05 ;===calib=== 2point calibration jsr lcdstro ;calibration current values lda n1 ;0mm jsr lcdbyto lda #'/' jsr lcdchro lda n2 ;160mm jsr lcdbyto bset 4,porta bset 5,porta ;leds on lego1: brclr 1,porta,lego1 lego2: brclr 2,porta,lego2 bclr 4,porta bclr 5,porta ;leds off when both sel & ent are released jsr del1s jsr del1s ;wait 2s ldhx #msg05a jsr lcdstro ;show instructions waitpb1: brset 2,porta,no2 ;if ent is not pressed, skip jmp nocalib ;if ent is pressed then cancel calibration no2: brclr 1,porta,do1st ;if sel is pressed then do 1st point cal bra waitpb1 ;otherwise wait for sel do1st: ldhx #msg05b ;1st point cal: show values jsr lcdstro clr cnt ;cnt will count 256 a/d readings clr rb clr ra ;rb:ra contains 16bit addup of those 256 values do256: lda #$c9 jsr lcdcmdo ;position lcd cursor at the right spot lda cnt deca jsr lcdbyto ;display current iteration $ff downto $00 lda #':' jsr lcdchro jsr adcbyti ;get reading add ra sta ra lda rb adc #$00 sta rb ;add into rb:ra (16 bit add) jsr lcdbyto ;show rb lda ra jsr lcdbyto ;then ra dbnz cnt,do256 ;and do 256x lsl ra ;get bit7 into carry bcc nochg ;if c=0 then no need to round up inc rb ;otherwise round up nochg: lda rb ;we can discard ra: average value is in rb ldhx #n1 ;point to flash location jsr wrflash ;burn it in! ldhx #msg05c ;ask for 160mm jsr lcdstro waitpb2: brset 2,porta,waitpb2 ;wait for ent ldhx #msg05d ;2nd point cal: show values jsr lcdstro clr cnt ;ditto as 1st point cal clr rb clr ra do256b: lda #$c9 jsr lcdcmdo lda cnt deca jsr lcdbyto lda #':' jsr lcdchro jsr adcbyti add ra sta ra lda rb adc #$00 sta rb f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3404 motorola sensor device data www.motorola.com/semiconductors jsr lcdbyto lda ra jsr lcdbyto dbnz cnt,do256b lsl ra bcc nochg2 inc rb nochg2: lda rb cmp n1 ;compare n2 to n1 bne validcal ;if different, we are ok ldhx #msg05e ;otherwise warn of invalid cal! jsr lcdstro jsr del1s jsr del1s jsr del1s ;wait 2s jmp calib ;try cal again validcal: ldhx #n2 jsr wrflash ;burn n2 into flash ldhx #msg05 ;and display new current cal values from flash jsr lcdstro lda n1 ;0mm value jsr lcdbyto lda #'/' jsr lcdchro lda n2 ;160mm value jsr lcdbyto jsr del1s jsr del1s jmp nocalib ;done! ;__________________________________________________________ level: lda #$01 ;===level=== main routine: displays level, flow & graphics jsr lcdcmdo ;clear screen lda #$0c jsr lcdcmdo ;cursor off lda #$88 ;position cursor at lcd graphics portion jsr lcdcmdo ;(2nd half of first line) clra ;and write ascii $00 through $07 fillgfx: jsr lcdchro ;which contain the graphics related to inca ;40 different readings cmp #$08 bne fillgfx lvl: ldhx #ramfree ;point to 40 pressure readings lda #$28 ;count down from 40 purge: clr 0,x ;clear all those locations incx ;next (h cannot change: we are in page0 ram) dbnza purge jsr adcbyta ;get lref: reference a/d reading jsr lfnx sta lgfx ;store in olevel graphicso lvlwarm: bset 4,porta bset 5,porta ;leds on during this cycle ldhx #ramfree ;point to 40 pressure readings mov #$27,ra ;count down from 39 shiftgfx: lda 1,x ;take location+1 sta 0,x ;and move to location+0, i.e. shift graphics left incx ;next x (once again: we are in page 0, no need to worry about h) dbnz ra,shiftgfx ;do this 39x lda #$80 jsr lcdcmdo lda lgfx jsr adcbyta ;get averaged a/d reading (i.e. lx) jsr lfnx ;lx:=(nxn1)*160/(n2n1) mov ra,oa clr rb cmp #$03 ;if <=2mm bcs lzero ;then oemptyo cmp #$9e bcc lsat ;then ofullo clrh ldx #$14 ;div by 20 div mov #$01,rb f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3405 motorola sensor device data www.motorola.com/semiconductors cmp #$01 beq lzero makerb lsl rb dbnza makerb bra lzero lsat: mov #$80,rb lzero: lda rb ldhx #ramfree+$27 ;last of the 40 sta 0,x ;put it at then end of the 40 bytes (new value), all others were shifted left clr weath lda rb beq donew ;$00 if oemptyo cmp #$80 bne notfull mov #$01,weath ;set ofullo if $80 bra donew notfull mov #$02,weath ;prepare for osteadyo if l(i)=l(i1) lda oa cmp lgfx beq donew mov #$03,weath ;ofillingo if l(i)>l(i1) bcc donew mov #$04,weath ;oemptyingo otherwise donew: lda oa sub lgfx sta ma ;rate:=l(i)l(i1) mov ra,lgfx ;update l(i1) lda #$80 ;******** now let's display the level in decimal ******** jsr lcdcmdo ;start on 1st character of 1st line lda oa clrh ldx #$64 clr rb div bne over100 lda #$20 ;prepare for a space in case first value is 0 jsr lcdchro bra lnext over100: jsr lcdnibo inc rb lnext: pshh pula clrh ldx #$0a ;divide by 10 div bne nospace tst rb bne nospace lda #$20 jsr lcdchro bra lnexta nospace: jsr lcdnibo ;display tens digit lnexta: pshh pula jsr lcdnibo ;and first decimal lda #'m' jsr lcdchro lda #'m' jsr lcdchro ;then the unit lda #$c0 ;******** now let's display the flow in decimal ******** jsr lcdcmdo ;position cursor on 1st character 2nd line lda ma lsla ;test sign of rate (in ma) bcc positiv ;if positive, then it's easy lda ma ;otherwise 1's complement of mb coma inca sta ma lda #'' jsr lcdchro ;display that minus sign f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3406 motorola sensor device data www.motorola.com/semiconductors bra goconv positiv: lda #'+' jsr lcdchro ;display the plus sign (to keep alignment) goconv: lda ma clrh ldx #$64 clr rb div bne over100b lda #$20 ;prepare for a space in case first value is 0 jsr lcdchro bra lnextb over100b: jsr lcdnibo inc rb lnextb: pshh pula clrh ldx #$0a ;divide by 10 div bne nospaceb tst rb bne nospaceb lda #$20 jsr lcdchro bra lnextab nospaceb: jsr lcdnibo ;display tens digit lnextab: pshh pula jsr lcdnibo ;and first decimal lda #'m' jsr lcdchro lda #'m' jsr lcdchro ;then the unit lda #'/' jsr lcdchro lda #'s' jsr lcdchro lda #$40 ;======== graphics update: tough stuff =========== jsr lcdcmdo ;prepare to write 8 bytes into cgram starting at @ $40 ldhx #ramfree ;point to 40 pressure readings (this reuses wrflash ram) mov #$08,da ;da will count those 8 cgram addresses cg8: lda 0,x sta nc lda 1,x sta nb lda 2,x sta na lda 3,x sta dc lda 4,x sta db ;readings 04 go into nc,nb,na,dc,db and will form 1 lcd special charac- ter mov #$08,ra ;ra will count the 8 bits fill: clr rb ;start with rb=0, this will eventually contain the data for cgram rol nc rol rb rol nb rol rb rol na rol rb rol dc rol rb rol db rol rb ;rotate left those 5 values and use carry bits to form rb (tough part) lda rb jsr lcdchro ;and put it into cgram dec ra ;do this 8 times to cover all 8 bits bne fill incx incx incx incx incx ;now point to next 5 values for next cgram address (5 values per charac- ter) f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3407 motorola sensor device data www.motorola.com/semiconductors dec da ;do this for all 8 cgram characters bne cg8 lda weath ;get weather variable and decide which message to display cmp #$04 bne try3210 ldhx #msg02e ;if $04 bra showit try3210: cmp #$03 bne try210 ldhx #msg02d ;if $03 bra showit try210: cmp #$02 bne try10 ldhx #msg02c ;if $02 bra showit try10: cmp #$01 bne try0 ldhx #msg02b ;if $01 bra showit try0: ldhx #msg02a ;otherwise this one showit: jsr lcdstro jsr del1s ;1s between pressure/altitude readings brset 1,porta,contin ;exit only if sel brset 2,porta,contin ;and ent pressed together jmp menu contin: jmp lvlwarm ;__________________________________________________________ lfnx: sub n1 ;*** px=f(nx,n2,n1) *** ldx #$a0 ;x160 mul sta na stx nb clr nc ;ncnbna:=(nxn1)*160 lda n2 sub n1 sta da clr db clr dc jsr ndivd ;rbra:=(nxn1)*160/(n2n1) lda ra rts ;__________________________________________________________ ndivd: clr ra ;rbra:=ncnbna/dcdbda clr rb ;destroys ncnbna and dcdbda keepatit: lda ra add #$01 sta ra lda rb adc #$00 sta rb ;increment rb:ra lda na sub da sta na lda nb sbc db sta nb lda nc sbc dc sta nc ;nc:nb:na:=nc:nb:nadc:db:da bcc keepatit ;keep counting how many times until overflow lda ra sub #$01 sta ra lda rb sbc #$00 sta rb ;we counted once too many, so undo that lsr dc ror db ror da ;divide dc:db:da by 2 lda na add da sta na lda nb f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3408 motorola sensor device data www.motorola.com/semiconductors adc db sta nb lda nc adc dc sta nc ;and add into nc:nb:na lsla bcs nornd ;if carry=1 then remainder<1/2 of dividend lda ra add #$01 sta ra lda rb adc #$00 sta rb ;otherwise add 1 to result nornd: rts ;__________________________________________________________ units: lda #$01 ;===units=== : displays a/d value, calib max/min values jsr lcdcmdo ;clear screen untwarm: lda #$0c jsr lcdcmdo ;cursor off lda #$80 jsr lcdcmdo ;(pos cursor begining of first line) jsr adcbyta ;get lref: reference a/d reading bset 4,porta ;sel ledon signals getting reading jsr lcdbyto jsr del1s bclr 4,porta ;sel ledoff signals reading received jsr adcbyta ;get lref: reference a/d reading tstlfnx: sub n1 ;*** px=f(nx,n2,n1) *** cmp #$00 ; if nx n1 > 0 then calculate bgt skipzero lda #'' ; else if nx << n1 then display error message to recalibrate jsr lcdbyto lda #'' jsr lcdbyto bra skipneg skipzero: ldx #$a0 ;x160 mul sta na stx nb clr nc ;ncnbna:=(nxn1)*160 lda #$90 jsr lcdcmdo ;(pos cursor 2nd half of first line) jsr lcdbyto ; display na lda #$87 jsr lcdcmdo lda nb jsr lcdbyto ; display nb skipneg: jsr del1s ;1s between pressure/altitude readings brset 1,porta,untcon ;exit only if sel brset 2,porta,untcon ;and ent pressed together jmp menu untcon: jmp untwarm ;__________________________ mancalib: jsr del1s rts test: jsr del1s f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3409 motorola sensor device data www.motorola.com/semiconductors rts ;__________________________________________________________ wrflash: sthx flshadr ;this is the address in the flash sta flshbyt ;and the byte we want to put there flash: tsx sthx memsp ;store sp in memsp, so it can be temporarily used as a 2nd index regis- ter ldhx #ramfree+1 ;sp now points to ram (remember to add 1 to the address!!!, hc08 quirk) txs ;sp changed (careful not to push or call subroutines) ldhx #ersflsh ;h:x points to beginning of flash programming code doall: lda 0,x ;get 1st byte from flash sta 0,sp ;copy it into ram aix #$0001 ;hx:=hx+1 ais #$0001 ;sp:=sp+1 cphx #lastbyt ;and continue until we reach the last byte bne doall ldhx memsp ;once done, restore the sp txs jsr ramfree ;and run the subroutine from ram, you cannot write the flash while rts ;running a code in it, so the ram has to take over for that piece ; ersflsh: lda #$02 ;textbook way to erase flash sta flcr lda flbpr clra ldhx flshadr sta 0,x bsr delayf lda #$0a sta flcr bsr delayf lda #$08 sta flcr bsr delayf clra sta flcr bsr delayf pgmflsh: lda #$01 ;textbook way to program flash sta flcr lda flbpr clra ldhx flshadr sta 0,x bsr delayf lda #$09 sta flcr bsr delayf lda flshbyt ldhx flshadr sta 0,x bsr delayf lda #$08 sta flcr bsr delayf clra sta flcr bsr delayf rts delayf: ldhx #$0005 mov #$36,tsc ;stop tim & / 64 sthx tmodh ;count h:x x 20us bclr 5,tsc ;start clock delayfls: brclr 7,tsc,delayfls rts lastbyt: nop ; general routines allinit: bset 0,config1 ;disable cop mov #$38,ddra ;pta0=mpak,pta1=sel,pta2=ent,pta3=e,pta4=rs,pta5=clk bclr 3,porta ;e=0 bclr 4,porta ;grn=off; rs=0 bclr 5,porta ;red=off; clk=0 mov #$30,adiclk ;adc clock /2 rts ; warmup: bclr 4,porta f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3410 motorola sensor device data www.motorola.com/semiconductors bclr 5,porta ;leds off lda #$0a ;prepare to do this 10x tenx: jsr del25ms ;delay bclr 4,porta bset 5,porta ;alternate on/off jsr del25ms bset 4,porta bclr 5,porta ;and off/on dbnza tenx ;10 times so the lcd can get ready (slow startup) jsr lcdinit ;now initialize it bclr 4,porta bclr 5,porta ;leds off rts ; bintasc: add #$30 ;add $30 (09 offset) cmp #$39 ;is it a number (09) ? bls d0to9b ;if so skip add #$07 ;else add $07 = total of $37 (af offset) d0to9b: rts ; del1s: pshh pshx ldhx #$c350 bra delmain del100ms: pshh pshx ldhx #$1388 bra delmain del50ms: pshh pshx ldhx #$09c4 bra delmain del25ms: pshh pshx ldhx #$04e2 bra delmain del5ms: pshh pshx ldhx #$00fa bra delmain del1ms: pshh pshx ldhx #$0032 bra delmain del100us: pshh pshx ldhx #$0005 bra delmain delmain: mov #$36,tsc ;stop tim & / 64 sthx tmodh ;count h:x x 20us bclr 5,tsc ;start clock delwait: brclr 7,tsc,delwait pulx pulh rts ; a/d routines adcbyti: mov #$00,adscr ;adc set to pta0 brclr 7,adscr,* ;wait for adc reading lda adr rts ;;;;;;;;;;;;;;;;;;;;;;;;;; adcbyta; clr cnt ;average 256 readings clr rb clr ra do256a: bsr adcbyti add ra sta ra lda rb adc #$00 sta rb f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3411 motorola sensor device data www.motorola.com/semiconductors dbnz cnt,do256a lsl ra bcc nochga inc rb nochga: lda rb rts ; lcd routines lcdinit: lda #$3c bsr lcdcmdo lda #$0c bsr lcdcmdo lda #$06 bsr lcdcmdo lda #$01 bsr lcdcmdo rts ; lcdcmdo: bsr shifta bclr 4,porta ;rs=0 for command bset 3,porta bclr 3,porta ;toggle e bsr del5ms rts ; lcdchro: bsr shifta bset 4,porta ;rs=1 for data bset 3,porta bclr 3,porta ;toggle e bsr del100us rts ; shifta: psha mov #$08,bb all8: lsla bcc shift0 shift1: bset 4,porta bra shift shift0: bclr 4,porta shift: bclr 5,porta bset 5,porta bclr 5,porta ;toggle clk dbnz bb,all8 pula rts ; lcdnibo: psha jsr bintasc ;convert binary to asc bsr lcdchro pula rts ; lcdbyto: psha psha lsra lsra lsra lsra bsr lcdnibo ;high nibble pula and #$0f bsr lcdnibo ;low nibble pula rts ; lcdstro: psha lda 0,x lcon: cmp #$80 bhs iscmd cmp #$1f bls iscmd isdta: bsr lcdchro ;output it to lcd reuse1: aix #$0001 lda 0,x ;indexed by y cmp #$40 ;continue until bne lcon ;character = '@' f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3412 motorola sensor device data www.motorola.com/semiconductors pula bclr 4,porta bclr 5,porta rts iscmd: bsr lcdcmdo bra reuse1 ; rom data msg01 db $01,$80,'*nitron & mpak* ' db $c0,'reference design','@' msg01a db $01,$80,'water level & ' db $c0,'flow v2.0','@' msg01b db $01,$80,'1:level/flow ' db $c0,'2:a/d sys demo','@' msg01c db $01,$80,'1:level/flow ' db $c0,'2:a/d sys demo','@' msg05 db $01,$80,'* calibration! *' db $c0,'curr lo/hi:','@' msg05a db $01,$80,'1st point: 0mm' db $c0,'sel:cal ent:quit','@' msg05b db $01,$80,'calibrating... ' db $c0,' 0mm: ','@' msg05c db $01,$80,'2nd point: 160mm' db $c0,'ent:continue ','@' msg05d db $01,$80,'calibrating... ' db $c0,' 160mm: ','@' msg05e db $01,$80,'invalid ' db $c0,'calibration! ','@' msg02a db $c8,' empty','@' msg02b db $c8,' full','@' msg02c db $c8,' steady','@' msg02d db $c8,' filling','@' msg02e db $c8,'emptying','@' menupos db $80,$c0 end references 1) baum, jeff, afrequency output conversion for mpx2000 series pressure sensors,o motorola application note an1316/d. 2) hamelain, jc, aliquid level control using a motorola pressure sensor,o motorola application note an1516/d. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3413 motorola sensor device data www.motorola.com/semiconductors

# ! " !! ! prepared by: marc osajda automotive sensors marketing sensor products division motorola semiconductors s.a. toulouse france braking systems different types of braking principles can be found in vehicles depending on whether the brake system is only activated by muscular energy or power assisted (partially or completely). muscular activated brakes are mostly found on motorcycles and very light vehicles. the driver's effort on the hand lever or pedal is directly transmitted via a hydraulic link to the brake pads. power assisted brakes are found on most passenger cars and some light vehicle trucks. in this case, the driver's effort is amplified by a brake booster to increase the force applied to the brake pedal. brake booster operation principle the vacuum brake booster is a system using the differential between atmospheric pressure and a lower pressure source (vacuum) to assist the braking operation. the brake booster is located between the brake pedal and the master cylinder. figure 1 shows a simplified schematic of a vacuum brake booster. when no brake pressure is applied on the push rod (brake pedal side), the air intake valve is closed and the vacuum valve open. thus, both the vacuum and working chambers are at the same pressure, typically around 70 kpa (70 kpa below atmospheric pressure). vacuum is generated by either the engine intake manifold or by an auxiliary vacuum pump. figure 1. brake booster simplified schematic connection to vacuum pump or engine intake manifold push rod from air intake valve working chamber vacuum chamber vacuum valve the brake pedal pistion rubber membrane push rod to master cylinder semiconductor application note rev 1 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3414 motorola sensor device data www.motorola.com/semiconductors figure 2. braking phase fp pv fp + fb pw once the brake pedal is activated (force fp), the vacuum valve is closed and the air intake valve is open proportionally to the displacement of the push rod (figure 2). the working chamber is progressively open to atmospheric pressure, which creates a differential between the vacuum chamber and the working chamber. this differential pressure applied to the surface (s) of the piston results in a force fb = (pw pv) x s . the forces fb + fp are then applied to the brake pads through the master cylinder and hydraulic links. when the brake pedal is released, the spring moves the piston back, closing the air intake valve and opening the vacuum valve to rebalance the pressure between the two chambers. vacuum generation on most passenger cars, vacuum is generated by the engine itself. when the engine throttle valve is closed, the displacement of the pistons produces vacuum in the intake manifold. thanks to a tube or hose connected between the engine intake manifold and the brake booster, vacuum can be applied to the chambers. a backslash valve inserted between the intake manifold and the booster maintains the vacuum in the booster when the engine throttle valve is open. this principle has some limitations, however. for example, it can be only used on engines that have the ability to generate enough vacuum. on diesel engines, which have no throttle valve, it is necessary to use an auxiliary pump to generate vacuum. this will also be the case on the gasoline direct injection (gdi) engine, where in some driving conditions (idle, lean burn) the electrically assisted throttle valve will be maintained slightly open. in this situation, the vacuum available on the intake manifold is not sufficient to provide an efficient braking. figure 3. vacuum pump monitoring pump control circuit electrical vacuum pump vacuum feedback vacuum generation pressure sensor bus interface therefore, it is necessary and desirable to use an electrical pump that will generate the vacuum for the brake booster. the use of an auxiliary electrical pump (figure 3) provides several advantages over the aintake manifoldo vacuum. ? vacuum generation is no longer related to the engine running condition. vacuum is only generated and con- trolled by the pump thanks to a vacuum pressure sensor that provides an accurate reading to the pump electrical control circuit. ? the electrical pump can be switched on and off based on the required vacuum. to compensate atmospheric pres- sure variation in order to maintain a constant booster effect, the pump also can be switched on independently from the atmospheric pressure. various algorithms for driving the pump can be implemented depending on the required braking conditions. ? pressure variations during braking can be measured, and the pump can be activated to generated additional vacuum if required to increase the braking force. ? leakage can be detected by the pressure sensors and the pump can be switched on to compensate them. the driver can be informed of any type of failure thanks to the bus interface. vacuum level, and thus available braking force can be communicated through the bus to other braking systems such as, for example, abs or esp. motorola, a worldwide leader in automotive semiconductors, has introduced a new integrate pressure sensor dedicated to vacuum measurements in applications such as brake booster monitoring. the singlechip vacuum sensor may be placed directly onto the pump electronic control unit or integrated as component within the brake booster, thus providing flexibility, system integration and reduced system cost. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3415 motorola sensor device data www.motorola.com/semiconductors motorola's new mpxv6115vc6u vacuum sensor piezoresistive/amplified sensors motorola's pressure sensors are based on a piezoresistive technology that consists of a silicon micromachined diaphragm and a diffused piezoresistive strain gauge. when vacuum or pressure is applied on the die, the diaphragm is deformed and stressed. the resulting constraints create a variation of resistance in the piezoresistive strain gauge. in order to read this variation, an excitation current passes through the gauge, and a voltage proportional to the applied pressure and excitation current appears between the voltage taps. to get an accurate pressure reading, such a sensing element needs usually to be calibrated, temperature compensated and amplified. in order to solve the inherent limitation of the basic sensing element, motorola produces an entire family of calibrated, thermally compensated and amplified pressure sensors (figure 4) called integrated pressure sensors (ips). the ips is a state of the art, monolithic, amplified and signalconditioned silicon pressure sensor. the sensor combines advanced micromachining techniques, thin film memorization and bipolar semiconductor processing to provide an accurate, highlevel analog output that is proportional to the applied pressure. ips sensors can be directly connected to an a/d converter. figure 4. integrated pressure sensor block diagram sensing p element thermal compensation amplifier v pressure measurement convention pressure measurements can be divided into three different categories: absolute, gage and differential pressure. absolute pressure refers to the absolute value of the force per unit area exerted on a surface by a fluid. therefore, the absolute pressure is the difference between the pressure at a given point in a fluid and the absolute zero of pressure or a perfect vacuum. gage pressure is the measurement of the difference between the absolute pressure and the local atmospheric pressure. local atmospheric pressure can vary depending on ambient temperature, altitude and local weather conditions. the standard atmospheric pressure at sea level and 20 c is 101.325 kpa absolute. when referring to pressure measurement, it is critical to specify what reference the pressure is related to: gage or absolute. a gage pressure by convention is always positive. a `negative' gage pressure is defined as vacuum. figure 5 shows the relationship between absolute, gage pressure and vacuum. differential pressure is simply the measurement of one unknown pressure with reference to another unknown pressure. the pressure measured is the difference between the two unknown pressures. since a differential pressure is a measure of one pressure referenced to another, it is not necessary to specify a pressure reference. figure 5. pressure convention absolute gage (+) local atmospheric pressure vacuum () atmospheric absolute f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3416 motorola sensor device data www.motorola.com/semiconductors transfer function the behavior of an ips is defined by a linear transfer function. this transfer function applies to all motorola's integrated pressure sensors whatever the pressure range and type of sensing element (absolute or differential). v out v s (p k1 k2) (pe tm v s k1) ? v out : sensor output voltage ? p: applied pressure in kpa ? vs: sensor supply voltage in v ? k1: sensitivity constant in v/v/kpa ? k2: offset constant inv/v ? pe: pressure error in kpa ? tm: temperature multiplier the constants, k1, k2, pe & tm are specific to each device, temperature and pressure encountered in the application. the variables p and vs are dependent on the user application but must remain within the operating specification of the device. the mpxv6115vc6u integrated pressure sensor the motorola mpxv6115vc6u gauge vacuum sensor, designed to measure pressure below the atmospheric pressure, is suitable for automotive application such as vacuum pump or brake booster monitoring. the mxpv4115v is also ideal for nonautomotive applications where vacuum control is required. the mpxv6115vc6u has the following basic characteristics (note: detailed characteristics of motorola's pressure sensors can be found on http://www.motorola.com/semiconductors). mpxv6115vc6u characteristics v out v s (p 0.007652 0.92) (pe tm v s 0.007652) figure 6. mpxv6115vc6u transfer function transfer function: v out = 2.30 v @ p = 60 kpa v out = v s ([0.007652 *p] + 0.92) 120 100 80 60 20 0 0 1 2 3 4 5 vacuum in kpa (below atmospheric pressure) typical v in volts @ v = 5 vdc 20 40 reference: atmospheric pressure vacuum s out ? p is the applied vacuum to the sensor pressure port. pressures below atmospheric pressure have a negative sign. for example, 50 kpa below atmospheric is p = 50 in the transfer function. for pressure higher than the atmospheric pressure, the device will electrically satu- rate. the sensor is designed to measure vacuum from 0 kpa (atmospheric pressure applied to the sensor pres- sure port) down to 115kpa. since the mpxv6115vc6u is using the atmospheric pressure as reference, 115 kpa can only be reached if the atmospheric pressure is higher or equal than 115 kpa. the device will electrically saturate for vacuum below 115 kpa. ? pe = 1.725 kpa (1.5% of full scale span) over the entire pressure range ? tm = 1 between 0 and +85 c, 3 at 40 c and +125 c. tm is a linear response from 40 to 0 c and from 85 to 125 c. the real intent for the pressuresensor user is to know the measured pressure. in this case it is preferable to express the transfer function as: p (v out v s 0.92) 0.007652 (pe tm) as an example, if v out = 2.30 v for a 5 vdc power supply and at 25 c ambient temperature, the measured vacuum is p = 60.1 kpa 1.725 kpa. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3417 motorola sensor device data www.motorola.com/semiconductors sensor packaging the packaging of a pressure sensor die is critical to achieve optimal performances of the final product. the package must isolate the pressure sensor die from unwanted external stress which can cause undesired drift of the electrical signal while being robust enough to support the pressure applied to the device without cracks, leaks or mechanical failures. it must be media compatible for the same reasons. figure 7. mounting suggestion customer flat ring applied pressure (or vacuum) pressure port application housing screw snapfit printed circuit board sop package case 482 the new small pressure sensor package from motorola addresses those requirements and lets designers mount a pressure sensor directly on a printed circuit board, thus providing great flexibility for space saving design. figure 7 shows a typical assembly using a small outline package (sop) case 48201. the sensor can be mounted on the printed circuit board by an automatic pick and place machine as with every other surface mount component. sealing is done by using a silicone flat ring inserted in the application housing. the printed circuit board must be maintained against the flat ring either by a snap fit, or by a screws as shown. the new small outline package (sop) is fabricated using polyphenyl sulfide (pps), a robust material, which can withstand high temperatures and is highly resistant to chemicals. consequently, the package is ideal for harsh environment such as automotive, industrial or medical systems. the small outline package is suitable for any of motorola's sensor chips from the basic uncompensated sensor to the fully integrated sensing solution that include amplifiers and other circuitry all on one chip. motorola's sensors using this package are available in both tubes and tape and reel configuration for high productivity on your assembly line. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3418 motorola sensor device data www.motorola.com/semiconductors
prepared by: memo romero and raul figueroa motorola sensor products division systems and applications engineering introduction this application note presents a design for a low pressure evaluation board using motorola mpx2010 series pressure sensors. by providing large gain amplification and allowing for package flexibility, this board is intended to serve as a design-in tool for customers seeking to quickly evaluate this family of pressure sensors. the mpx2010 family of pressure sensors appeals to customers needing to measure small gauge, vacuum, or differential pressures at a low cost. however, different applications present designin challenges for these sensors. for very low pressure sensing, large signal amplification is required, with gains substantially larger than what is provided in motorola's current integrated pressure sensor portfolio. in terms of packaging, customers often need more mechanical flexibility such as smaller size, dual porting or both. in many cases, customers often lack the engineering resources, time or expertise to evaluate the sensor. the low-pressure evaluation board, shown in figure 1, facilitates the design-in-process by providing large signal gain and by providing for different package designs in a relatively small footprint. circuit description for adequate and stable signal gain and output flexibility, a twostage differential op-amp circuit with analog or switch output is utilized, as shown in figure 2. the four op-amps are packaged in a single 14 pin quad package. there are several features to note about the circuitry. the first gain stage is accomplished by feeding both pressure sensor outputs (v s & v s +) into the non-inverting inputs of operational amplifiers. these op-amps are used in the standard non-inverting feedback configuration. with the condition that resistors r2=r3, and r1=r4 (as closely as possible), this configuration results in a gain of g1= r4/r3+1 . the default gain is 101, but there are provisions for easily changing this value. the signal v (op-amp pin 7) is then calculated as: v 1 = g1*(v s+ v s ) + v offset . .equation (1) figure 1. low pressure evaluation board semiconductor application note f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3419 motorola sensor device data www.motorola.com/semiconductors figure 2. circuit schematic v offset is the reference voltage for the first op-amp and is pre-set with a voltage divider from the supply voltage. this value is set to be 6.7 percent of the supply voltage. it is important to keep this value relatively small simply because it too is amplified by the second gain stage. it is also desirable to have resistors r7 and r8 sufficiently large to reduce power consumption. the second gain stage takes the signal from the first gain stage, v, and feeds it into the non-inverting input of a single op-amp. this op-amp is also configured with standard non-inverting feedback, resulting in a gain of g2=r5/r6+1 . the default value is set to 2, but can easily be changed. the signal produced at the output of the second stage amplifier, v (op-amp pin 8) is the fully amplified signal. this is calculated as v 2 = g2* v 1 . .equation (2) from this point, there are two possible output types available. one is a simple follower circuit, as shown in figure 3, in which the circuit output, vout (op-amp pin 14), is essentially a buffered v signal. this analog output option is available for applications in which the real time nature of the pressure signal needs to be measured. this option is selected by connecting jumpers j5 and j6. j4 and j7 are not connected for analog output. the second output choice, a switch output as shown in figure 4, is accomplished by setting jumpers j4 and j7, and leaving j5 and j6 unconnected. this is appropriate for applications in which a switching function is desired. in this case, the fourth op-amp is configured as a comparator, which will invert v 2 , high or low, depending on whether v 2 is larger or smaller than the preset reference signal, set by trim-pot r9. this signal can be used to simulate a real world threshold. figure 3. analog output jumper settings figure 4. switch output jumper settings f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3420 motorola sensor device data www.motorola.com/semiconductors table 1 shows the jumper settings for both analog and switches outputs. table 1. output jumper settings output jp4 jp5 jp6 jp7 analog out in in out switch in out out in for the switch output option, it is desirable to apply some hysteresis on the output signal to make it relatively immune to potential noise that may be present in the voltage signal as it reaches and passes the threshold value. this is accomplished with feedback resistor r10. from basic op-amp theory, it can be shown that the amount of hysteresis is computed as follows: v h = vout *[1(10 / ( r10 + r pot-eff))] where: v h is the output voltage attenuation, due to hystere- sis, in volts vout is the output voltage (railed hi or low) r10 is the feedback resistor, = 50k rpot-eff is the effective potentiometer resistance v h may vary depending on the particular value of the potentiometer. figure 5a. output transition without hysteresis figure 5b. output transition with hysteresis to take an example, suppose that the supply voltage, vs is 5 volts, and the threshold is set to 60 percent of vs, or 3 volts. this corresponds to one leg of the 1k potentiometer set to 0.4k while the other is set to 0.6k. thus the effective pot resistance is 0.4k // 0.6k = 0.24k. therefore, v h = 5v* [1 (50k/(50k + 0.24k))] = 24 mv. under these conditions, v signals passing through the threshold will not cause vout to oscillate between vs and ground as long as noise and signal variations in v are less than 24mv during the transition. figure 5. illustrates the benefit of having a hysteresis feedback resistor. gain customization the low-pressure evaluation board comes with default gains for both g1 and g2. g1 is factory set at 101, while g2 is set to 1. jumpers jp1, jp2 and jp3 physically connect the resistors that produce these default gains. three resistor sockets (r11, r41 and r51) are provided in parallel with r1, r4 and r5, respectively. by removing jumpers jp1,jp2 and jp3, and soldering different resistor values in the appropriate sockets, different gain values can be achieved. the limit on the largest overall gain that can be used is determined by opamp saturation. thus if gain values are chosen such that the output would be larger than the supply voltage, then the opamp would saturate, and the pressure would not be accurately reflected. table 2 outlines the jumper settings for customizing the gain. table 2. resistor and jumper settings for gain customization gain resistors jumpers remarks g1 g2 r11 r41 r51 jp1 jp2 jp3 101 2 no load no load no load in in in default user set 2 load load no load out out in r11=r41 101 user set no load no load load in in out user set user set load load load out out out r11=r41 design considerations since the evaluation board is primarily intended for lowpressure gage and differential applications, large gain values can be utilized for pressures less than 1.0 kpa. for example if g1 is set to 101, and g2 set to 6, then the total gain is 606. inherent in the mpx2010 family of pressure sensors is a zero-pressure offset voltage, which can be up to 1 mv. this offset is amplified by the circuit and appears as a dc offset at vout with no pressure applied. the op-amp also has a voltage offset specification, though for the recommended op-amp this value is small and does not contribute significantly to the vout offset. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3421 motorola sensor device data www.motorola.com/semiconductors for example, if the evaluation board is being used under the following conditions: vs = 3v g1 = 101 g2 = 6 mpx2010 zero pressure offset = 0.3mv at this supply voltage, voffset can be calculated to be 6.7% x 3v = 0.2v. the voltage v, due simply to the zero pressure sensor offset voltage of 0.3mv, can be calculated from equation (1): v 1 = 0.3mv * 101 + 0.2v = 0.23v the voltage after the second gain stage comes from equation (2), v 2 = 6 x 0.23v = 1.38 v. therefore, before any pressure is applied to the sensor, a 1.38v dc signal will appear at v. since the supply voltage is 3v, the available signal for actual pressure is 1.62 v. with a total gain of g1 x g2 = 606, the largest raw pressure signal that can be accurately measured would be 1.62v/606 = 2.67 mv. for the mpx2010 family operating at vs = 3v, this corresponds to roughly 3.5 kpa. the board lends itself well to system integration via an a/d converter and microprocessor. for particular applications, general knowledge of the expected pressure signal can aid in choosing the proper customized gain. this will avoid op-amp saturation and will also ensure that the full-scale output signal is suitable for a/d conversion. to take another example, suppose that a particular application has the following constraints: supply voltage, vs = 5.0 v, (thus voffset = 6.7% x 5 = 0.335 v) sensor zeropressure offset voltage, v zp = 0.3mv expected pressure range = 0e2 kpa, (corresponds to v sensor-max = 2.5mv @ 5v) desired maximum output range, v 2max = 2v (assume vmin = 2v, v 2max = 4v for reasonable a/d resolution) by manipulating equations (1) and (2) it can be shown that, v 2max = g t x v sensormax where g t is the total gain, equal to g1g2. thus g t = 2v/2.5mv = 800 to find g1 and g2, evaluate v 2min at the zero pressure condition. v 2min = g2 v 1min , but v 1min = g1 v zp + v offset thus v 2min = g t v zp + g2 v offset solving for g2, g2 = (v 2min g t v zp )/ v offset numerically, g2 = (2v e (800x.0003v))/.335v g2 = 5.2, and g1 = gt /g2 = 152 board layout & content the low-pressure evaluation board has been designed using standard components. the only item that requires careful selection is the operation amplifier ic. because the selected gain may be relatively high as in the previous example, it is essential that this device have a low offset voltage. a device with a typical voltage offset of 35 mv has been selected. even with a gain of 1500, this will result in a 52mv offset. table 3 is a parts list for the board layout shown in figure1. table 3. parts list ref. qty. description value vendor part no. x1 1 pressure sensor 10 kpa motorola mpx2010 mpxc2011 c1 1 vcc cap 1 uf generic c2 1 op-amp cap 0.1 uf generic c3 1 2nd stage cap 4700 pf generic d1 1 led generic for u1 1 op-amp socket generic u1 1 op-amp analog devices op496gp r1, r4 2 1/4 w resistor 100k generic r2,r3, r5,r6 4 1/4 w resistor 1k generic r7 1 1/4 w resistor 6.8k generic r8 1 1/4 w resistor 510 generic r9 1 potentiometer 1k bourns 3386p102 r10 1 1/4 w resistor 51k generic r11 1 1/4 w resistor custom generic r12 1 1/4 w resistor 2k generic r41 1 1/4 w resistor custom generic r51 1 1/4 w resistor custom generic jp1 jp7 7 jumper generic j1 1 3 pos connector phoenix mkds1 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3422 motorola sensor device data www.motorola.com/semiconductors figure 6 illustrates the particular layout chosen for the evaluation board (led and r12 are not shown). this layout can serve as a fully functional standalone board or can be the basis for integration into a system level layout. through hole mounted components have been selected, and this dictates the particular footprint dimensions. however, with surface mount components, this layout can be made significantly smaller. component side figure 6a. board layout figure 6b. board layout back side evaluation notes: this board is designed to run from a regulated power source or from batteries. since the pressure sensors are ratiometric (meaning that the output scales with the applied supply voltage), supply voltages ranging from 3v to 10v can be used. the specified op-amp operates well within these values. in terms of sensor packages, four variations are recommended. they are the mpx2010d, mpx201dp, mpx2010gp and the mpxc2011dt1. either of these sensors can be directly mounted on the board itself or can be remotely mounted and connected to it via wires. the customer can select the proper package depending on size requirements and on whether gauge, vacuum or differential pressure will be sensed. in particular, the mpxc2011dt1, known as the chippak sensor, is a very small package and can be used to sense differential and vacuum pressure provided that ports are attached on each side as shown in figure 1. note that motorola does not provide these ports as standard products. since the output signal of the evaluation board can be fined tuned to be a very measurable voltage, interfacing the board to an a/d, microprocessor, or other circuitry is very straightforward. conclusion the low-pressure evaluation board provides design flexibility in terms of amplification, output type and packaging. gains ranging from 50 up to 1500 can be easily implemented by simply soldering specific resistors and manipulating a few jumpers. jumpers also control the type of output and allow the user to select analog or switching signals. two sets of through hole sensor connections are provided for various pressure sensor packages, and customers are free to remotely mount the board via wires. in many applications, such as hvac systems or medical respiratory equipment, quick and effective component evaluation is critical. the flexible features of this board allow a customer to reduce development time. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3423 motorola sensor device data www.motorola.com/semiconductors package outline dimensions case 34415 issue aa style 1: pin 1. ground 2. + output 3. + supply 4. output style 1: pin 1. ground 2. + output 3. + supply 4. output case 344b01 issue b seating plane b n r c j t d f u h l port #1 positive pressure pin 1 a q s k g 4 pl p s q m 0.25 (0.010) t s s m 0.13 (0.005) q s t 12 34 notes: 1. dimensioning and tolerancing per ansi y14.5, 1982. 2. controlling dimension: inch. dim min max min max millimeters inches a 1.145 1.175 29.08 29.85 b 0.685 0.715 17.40 18.16 c 0.305 0.325 7.75 8.26 d 0.016 0.020 0.41 0.51 f 0.048 0.064 1.22 1.63 g 0.100 bsc 2.54 bsc h 0.182 0.194 4.62 4.93 j 0.014 0.016 0.36 0.41 k 0.695 0.725 17.65 18.42 l 0.290 0.300 7.37 7.62 n 0.420 0.440 10.67 11.18 p 0.153 0.159 3.89 4.04 q 0.153 0.159 3.89 4.04 r 0.230 0.250 5.84 6.35 s u 0.910 bsc 23.11 bsc 0.220 0.240 5.59 6.10 (p1) m a m 0.136 (0.005) t 1234 pin 1 r n l g f d 4 pl seating plane t c m j b a dim min max min max millimeters inches a 0.595 0.630 15.11 16.00 b 0.514 0.534 13.06 13.56 c 0.200 0.220 5.08 5.59 d 0.016 0.020 0.41 0.51 f 0.048 0.064 1.22 1.63 g 0.100 bsc 2.54 bsc j 0.014 0.016 0.36 0.40 l 0.695 0.725 17.65 18.42 m 30 nom 30 nom n 0.475 0.495 12.07 12.57 r 0.430 0.450 10.92 11.43 notes: 1. dimensioning and tolerancing per asme y14.5m, 1994. 2. controlling dimension: inch. 3. dimension a is inclusive of the mold stop ring. mold stop ring not to exceed 16.00 (0.630). dambar trim zone: f this is included within dim. afo 8 pl 1 23 4 y z y 0.048 0.052 1.22 1.32 z 0.106 0.118 2.68 3.00 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3424 motorola sensor device data www.motorola.com/semiconductors package outline dimensions (continued) style 1: pin 1. ground 2. + output 3. + supply 4. output port #2 port #1 port #2 vacuum seating plane seating plane k s w h l u f g d port #1 positive pressure q 12 4 3 pin 1 4 pl p t t s q m 0.25 (0.010) t s s m 0.13 (0.005) q s t b n j c v r notes: 1. dimensioning and tolerancing per ansi y14.5m, 1982. 2. controlling dimension: inch. dim min max min max millimeters inches a 1.145 1.175 29.08 29.85 b 0.685 0.715 17.40 18.16 c 0.405 0.435 10.29 11.05 d 0.016 0.020 0.41 0.51 f 0.048 0.064 1.22 1.63 g 0.100 bsc 2.54 bsc h 0.182 0.194 4.62 4.93 j 0.014 0.016 0.36 0.41 k 0.695 0.725 17.65 18.42 l 0.290 0.300 7.37 7.62 n 0.420 0.440 10.67 11.18 p 0.153 0.159 3.89 4.04 q 0.153 0.159 3.89 4.04 r 0.063 0.083 1.60 2.11 s u 0.910 bsc 23.11 bsc v 0.248 0.278 6.30 7.06 w 0.310 0.330 7.87 8.38 a 0.220 0.240 5.59 6.10 (p2) (p1) case 344c01 issue b case 344d01 issue b style 1: pin 1. ground 2. + output 3. + supply 4. output notes: 1. dimensioning and tolerancing per ansi y14.5, 1982. 2. controlling dimension: inch. seating plane b n r c j t d f u l h port #2 vacuum positive pressure pin 1 a q s k g 4 pl p s q m 0.25 (0.010) t s s m 0.13 (0.005) q s t dim min max min max millimeters inches a 1.145 1.175 29.08 29.85 b 0.685 0.715 17.40 18.16 c 0.305 0.325 7.75 8.26 d 0.016 0.020 0.41 0.51 f 0.048 0.064 1.22 1.63 g 0.100 bsc 2.54 bsc h 0.182 0.194 4.62 4.93 j 0.014 0.016 0.36 0.41 k 0.695 0.725 17.65 18.42 l 0.290 0.300 7.37 7.62 n 0.420 0.440 10.67 11.18 p 0.153 0.159 3.89 4.04 q 0.153 0.158 3.89 4.04 r 0.230 0.250 5.84 6.35 s u 0.910 bsc 23.11 bsc 12 34 0.220 0.240 5.59 6.10 (p2) (p1) f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3425 motorola sensor device data www.motorola.com/semiconductors package outline dimensions (continued) style 1: pin 1. ground 2. + output 3. + supply 4. output s notes: 1. dimensioning and tolerancing per ansi y14.5m, 1982. 2. controlling dimension: inch. dim min max min max millimeters inches a 0.690 0.720 17.53 18.28 b 0.245 0.255 6.22 6.48 c 0.780 0.820 19.81 20.82 d 0.016 0.020 0.41 0.51 f 0.048 0.064 1.22 1.63 g 0.100 bsc 2.54 bsc j 0.014 0.016 0.36 0.41 k 0.345 0.375 8.76 9.53 n 0.300 0.310 7.62 7.87 r 0.178 0.186 4.52 4.72 s v 0.182 0.194 4.62 4.93 back side vacuum pin 1 4 pl port #1 positive pressure 4 seating plane 32 1 k a g f d m b m 0.13 (0.005) t c n r v j b t 0.220 0.240 5.59 6.10 (p1) (p2) case 344e01 issue b notes: 1. dimensioning and tolerancing per ansi y14.5m, 1982. 2. controlling dimension: inch. style 1: pin 1. ground 2. v (+) out 3. v supply 4. v () out e c j v t port #1 positive pressure pin 1 4 pl d p g k m q m 0.25 (0.010) t u a f s n b s p m 0.13 (0.005) q s t dim min max min max millimeters inches a 1.080 1.120 27.43 28.45 b 0.740 0.760 18.80 19.30 c 0.630 0.650 16.00 16.51 d 0.016 0.020 0.41 0.51 e 0.160 0.180 4.06 4.57 f 0.048 0.064 1.22 1.63 g 0.100 bsc 2.54 bsc j 0.014 0.016 0.36 0.41 k n 0.070 0.080 1.78 2.03 p 0.150 0.160 3.81 4.06 q 0.150 0.160 3.81 4.06 r 0.440 0.460 11.18 11.68 s 0.695 0.725 17.65 18.42 u 0.840 0.860 21.34 21.84 v 0.182 0.194 4.62 4.92 q r 4321 0.220 0.240 5.59 6.10 (p1) case 344f01 issue b f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3426 motorola sensor device data www.motorola.com/semiconductors package outline dimensions (continued) case 423a03 issue c dim a min max min max millimeters 6.10 6.60 0.240 0.260 inches b 8.89 9.40 0.350 0.370 c 3.56 3.81 0.140 0.150 d1 0.30 0.51 0.012 0.020 e 2.24 2.59 0.088 0.102 f 3.12 3.25 0.123 0.128 g 1.14 1.40 0.045 0.055 h 0.94 1.19 0.037 0.047 j 0.18 0.28 0.007 0.011 k 3.05 3.56 0.120 0.140 l 2.41 2.67 0.095 0.105 m 4.19 4.45 0.165 0.175 n 5.66 6.07 0.223 0.239 v 2.67 2.92 0.105 0.115 aa 2.41 2.72 0.095 0.107 ab 0.38 0.89 0.015 0.035 ac 3.05 4.45 0.120 0.175 ad 2.54 2.92 0.100 0.115 style 1: pin 1. v cc 2. +out 3. out 4. ground ab ad aa f ac back view g d1 v n front view m a 12 4 3 c l b f k h e j t end view d2 detail a detail a d2 0.36 0.56 0.014 0.022 notes: 1. dimensioning and tolerancing per ansi y14.5m, 1982. 2. controlling dimension: inch. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3427 motorola sensor device data www.motorola.com/semiconductors package outline dimensions (continued) case 48201 issue o dim min max min max millimeters inches a 10.54 0.425 0.415 10.79 b 10.54 0.425 0.415 10.79 c 5.38 0.230 0.212 5.84 d 0.96 0.042 0.038 1.07 g 0.100 bsc 2.54 bsc h 0.002 0.010 0.05 0.25 j 0.009 0.011 0.23 0.28 k 0.061 0.071 1.55 1.80 m 0 7 0 7 n 0.405 0.415 10.29 10.54 s 0.709 0.725 18.01 18.41 notes: 1. dimensioning and tolerancing per ansi y14.5m, 1982. 2. controlling dimension: inch. 3. dimension a and b do not include mold protrusion. 4. maximum mold protrusion 0.15 (0.006). 5. all vertical surfaces 5 typical draft. s d g 8 pl 4 5 8 1 n s b m 0.25 (0.010) a s t a b c m j k pin 1 identifier h seating plane t case 482a01 issue a dim min max min max millimeters inches a 10.54 0.425 0.415 10.79 b 10.54 0.425 0.415 10.79 c 12.70 0.520 0.500 13.21 d 0.96 0.042 0.038 1.07 g 0.100 bsc 2.54 bsc h 0.002 0.010 0.05 0.25 j 0.009 0.011 0.23 0.28 k 0.061 0.071 1.55 1.80 m 0 7 0 7 n 0.444 0.448 11.28 11.38 s 0.709 0.725 18.01 18.41 notes: 1. dimensioning and tolerancing per ansi y14.5m, 1982. 2. controlling dimension: inch. 3. dimension a and b do not include mold protrusion. 4. maximum mold protrusion 0.15 (0.006). 5. all vertical surfaces 5 typical draft. s d g 8 pl 4 5 8 1 s b m 0.25 (0.010) a s t a b c m j k pin 1 identifier h seating plane t n v w v 0.245 0.255 6.22 6.48 w 0.115 0.125 2.92 3.17 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3428 motorola sensor device data www.motorola.com/semiconductors package outline dimensions (continued) case 482b03 issue b dim min max min max millimeters inches a 10.54 0.425 0.415 10.79 b 10.54 0.425 0.415 10.79 c 5.33 0.220 0.210 5.59 d 0.66 0.034 0.026 0.864 g 0.100 bsc 2.54 bsc j 0.009 0.011 0.23 0.28 k 0.100 0.120 2.54 3.05 m 0 15 0 15 n 0.405 0.415 10.29 10.54 s 0.540 0.560 13.72 14.22 notes: 1. dimensioning and tolerancing per ansi y14.5m, 1982. 2. controlling dimension: inch. 3. dimension a and b do not include mold protrusion. 4. maximum mold protrusion 0.15 (0.006). 5. all vertical surfaces 5 typical draft. 6. dimension s to center of lead when formed parallel. pin 1 identifier k seating plane t s g 4 5 8 1 a b c m j n d 8 pl s b m 0.25 (0.010) a s t detail x detail x case 482c03 issue b dim min max min max millimeters inches a 10.54 0.425 0.415 10.79 b 10.54 0.425 0.415 10.79 c 12.70 0.520 0.500 13.21 d 0.66 0.034 0.026 0.864 g 0.100 bsc 2.54 bsc j 0.009 0.011 0.23 0.28 k 0.100 0.120 2.54 3.05 m 0 15 0 15 n 0.444 0.448 11.28 11.38 s 0.540 0.560 13.72 14.22 notes: 1. dimensioning and tolerancing per ansi y14.5m, 1982. 2. controlling dimension: inch. 3. dimension a and b do not include mold protrusion. 4. maximum mold protrusion 0.15 (0.006). 5. all vertical surfaces 5 typical draft. 6. dimension s to center of lead when formed parallel. pin 1 k seating plane t s g 4 5 8 1 a b c n v w m j v 0.245 0.255 6.22 6.48 w 0.115 0.125 2.92 3.17 identifier d 8 pl s b m 0.25 (0.010) a s t detail x detail x f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3429 motorola sensor device data www.motorola.com/semiconductors package outline dimensions (continued) basic element (a, d) case 86708 issue n style 1: pin 1. vout 2. ground 3. vcc 4. v1 5. v2 6. vex pin 1 f g n l r c b m j s a 123456 6 pl d seating plane t m a m 0.136 (0.005) t dim min max min max millimeters inches a 0.595 0.630 15.11 16.00 b 0.514 0.534 13.06 13.56 c 0.200 0.220 5.08 5.59 d 0.027 0.033 0.68 0.84 f 0.048 0.064 1.22 1.63 g 0.100 bsc 2.54 bsc j 0.014 0.016 0.36 0.40 l 0.695 0.725 17.65 18.42 m 30 nom 30 nom n 0.475 0.495 12.07 12.57 r 0.430 0.450 10.92 11.43 s 0.090 0.105 2.29 2.66 positive pressure (p1) notes: 1. dimensioning and tolerancing per ansi y14.5m, 1982. 2. controlling dimension: inch. 3. dimension a is inclusive of the mold stop ring. mold stop ring not to exceed 16.00 (0.630). pressure side ported (ap, gp) case 867b04 issue f style 1: pin 1. v out 2. ground 3. v cc 4. v1 5. v2 6. v ex seating plane r n c j pin 1 m q m 0.25 t b 6x d g f s k v s p m 0.173 q s t l u a 1 2 34 5 6 notes: 1. dimensions are in millimeters. 2. dimensions and tolerances per asme y14.5m, 1994. dim min max millimeters a 29.08 29.85 b 17.4 18.16 c 7.75 8.26 d 0.68 0.84 f 1.22 1.63 g 2.54 bsc j 0.36 0.41 k 17.65 18.42 l 7.37 7.62 n 10.67 11.18 p 3.89 4.04 q 3.89 4.04 r 5.84 6.35 s 5.59 6.1 u 23.11 bsc v 4.62 4.93 t p p q q f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3430 motorola sensor device data www.motorola.com/semiconductors package outline dimensions (continued) pressure and vacuum sides ported (dp) case 867c05 issue f notes: 1. dimensioning and tolerancing per ansi y14.5m, 1982. 2. controlling dimension: inch. style 1: pin 1. v out 2. ground 3. v cc 4. v1 5. v2 6. v ex r x 123456 dim min max min max millimeters inches a 1.145 1.175 29.08 29.85 b 0.685 0.715 17.40 18.16 c 0.405 0.435 10.29 11.05 d 0.027 0.033 0.68 0.84 f 0.048 0.064 1.22 1.63 g 0.100 bsc 2.54 bsc j 0.014 0.016 0.36 0.41 k 0.695 0.725 17.65 18.42 l 0.290 0.300 7.37 7.62 n 0.420 0.440 10.67 11.18 p 0.153 0.159 3.89 4.04 q 0.153 0.159 3.89 4.04 r 0.063 0.083 1.60 2.11 s u 0.910 bsc 23.11 bsc v 0.182 0.194 4.62 4.93 w 0.310 0.330 7.87 8.38 x 0.248 0.278 6.30 7.06 port #2 vacuum (p2) port #1 positive port #1 pin 1 port #2 positive vacuum pressure seating plane seating plane t t p g c j n b f d w v l u 6 pl s k q a m q m 0.25 (0.010) t m a m 0.13 (0.005) pressure (p1) 0.220 0.240 5.59 6.10 (p1) (p2) pressure side ported (as, gs) case 867e03 issue d notes: 1. dimensioning and tolerancing per ansi y14.5m, 1982. 2. controlling dimension: inch. style 1: pin 1. v out 2. ground 3. v cc 4. v1 5. v2 6. v ex a 654321 c k n e b port #1 positive pressure j t s g f d 6 pl pin 1 m b m 0.13 (0.005) t dim min max min max millimeters inches a 0.690 17.53 18.28 b 0.245 0.255 6.22 6.48 c 0.780 0.820 19.81 20.82 d 0.027 0.033 0.69 0.84 e 0.178 0.186 4.52 4.72 f 0.048 0.064 1.22 1.63 g 0.100 bsc 2.54 bsc j 0.014 0.016 0.36 0.41 k 0.345 0.375 8.76 9.53 n 0.300 0.310 7.62 7.87 s 0.220 0.240 5.59 6.10 0.720 v v 0.182 0.194 4.62 4.93 (p1) f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3431 motorola sensor device data www.motorola.com/semiconductors package outline dimensions (continued) pressure side ported (asx, gsx) case 867f03 issue d style 1: pin 1. v out 2. ground 3. v cc 4. v1 5. v2 6. v ex notes: 1. dimensioning and tolerancing per ansi y14.5m, 1982. 2. controlling dimension: inch. c e v j port #1 positive pressure t p m q m 0.25 (0.010) t d f g 6 pl k s pin 1 u a r b q n s p m 0.13 (0.005) q s t 654321 dim min max min max millimeters inches a 1.080 1.120 27.43 28.45 b 0.740 0.760 18.80 19.30 c 0.630 0.650 16.00 16.51 d 0.027 0.033 0.68 0.84 e 0.160 0.180 4.06 4.57 f 0.048 0.064 1.22 1.63 g 0.100 bsc 2.54 bsc j 0.014 0.016 0.36 0.41 k n 0.070 0.080 1.78 2.03 p 0.150 0.160 3.81 4.06 q 0.150 0.160 3.81 4.06 r 0.440 0.460 11.18 11.68 s 0.695 0.725 17.65 18.42 u 0.840 0.860 21.34 21.84 v 0.182 0.194 4.62 4.93 0.220 0.240 5.59 6.10 (p1) f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3432 motorola sensor device data www.motorola.com/semiconductors package outline dimensions (continued) case 131703 issue b 0.025 0.298 0.050 a m 0.004 b c 0.165 0.280 a b c notes: 1. all dimensions are in inches. 2. dimensioning and tolerancing per asme y14.5m1994. 3. dimensions do not include mold flash or protrusions. mold flash or protrusions shall not exceed .006 inches per side. 4. all vertical surfaces to be 5 maximum. 5. dimension does not include dambar protrusion. allowable dambar protrusion shall be .008 inches maximum. 0.004 a 0.006 b c gage plane detail e 0.023 0.010 .010 8x 0.014 2x detail e seating plane 0.019 0.300 0.280 0.300 0.400 0.420 3 5 0.278 0.145 0.002 0.013 10 0 3 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3433 motorola sensor device data www.motorola.com/semiconductors package outline dimensions (continued) case 1317a01 issue a 0.025 0.130 0.050 a m 0.004 b c 0.390 0.325 a b c notes: 1. all dimensions are in inches. 2. dimensioning and tolerancing per asme y14.5m1994. 3. dimensions do not include mold flash or protrusions. mold flash or protrusions shall not exceed .006 inches per side. 4. all vertical surfaces to be 5 maximum. 5. dimension does not include dambar protrusion. allowable dambar protrusion shall be .008 inches maximum. 0.004 a 0.006 b c gage plane detail e 0.048 0.010 .014 8x 0.014 2x detail e seating plane 0.018 0.345 0.325 0.345 0.400 0.420 5 0.110 0.370 0.002 0.038 10 0 0.200 0.180 0.280 a b 0.300 0.280 0.300 3 3 bottom view f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3434 motorola sensor device data www.motorola.com/semiconductors package outline dimensions (continued) case 132002 issue a dim min max inches a .155 .165 a1 .002 .010 b .014 .018 b1 .120 .130 d .245 .255 e .475 .485 e e/2 l .038 .048 e1 .325 .335 0 7 .025 bsc .050 bsc q notes: 1. dimensions are in inches. 2. interpret dimensions and tolerances per asme y14.5m1994. 3. dimensions odo and oe1o do not include mold flash or protrusion. mold flash or protrusion shall not exceed .006o per side. 4. all vertical surfaces to be 5 maximum. 5. dimensions obo does not include dambar protrusion. allowable dambar protrusion shall be .008 maximum. b1 e e/2 e a m 0.004 b c a 0.006 b c 4x b 2x a m 0.004 b c e1 a c 0.004 detail e seating plane gage plane detail e l a1 q .014 b d a pin 1 pin 4 style 1: pin 1. gnd 2. +vout 3. vs 4. vout f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3435 motorola sensor device data www.motorola.com/semiconductors package outline dimensions (continued) case 1320a02 issue o dim min max inches a .377 .397 a1 .002 .010 b .014 .018 b1 .120 .130 d .245 .255 e .475 .485 e e/2 l .013 .023 e1 .325 .335 0 7 .025 bsc .050 bsc q notes: 1. dimensions are in inches. 2. interpret dimensions and tolerances per asme y14.5m1994. 3. dimensions odo and oe1o do not include mold flash or protrusion. mold flash or protrusion shall not exceed .006o per side. 4. all vertical surfaces to be 5 maximum. 5. dimensions obo does not include dambar protrusion. allowable dambar protrusion shall be .008 maximum. b1 e e/2 e a m 0.004 b c a 0.006 b c 4x b 2x a m 0.004 b c e1 a c 0.004 detail e seating plane gage plane detail e l a1 q .014 b d a m .283 .293 n .363 .373 p .107 .117 s .192 .202 n s p f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3436 motorola sensor device data www.motorola.com/semiconductors package outline dimensions (continued) case 135101 issue o d e e/2 n e a m 0.004 (0.1) b c a e1 a b c 0.004 (0.1) a 0.006 (0.15) b c 8x b 2 places 4 tips detail g seating plane 8x p 1 4 8 5 notes: 1. controlling dimension: inch. 2. interpret dimensions and tolerances per asme y14.5m1994. 3. dimensions odo and oe1o do not include mold flash or protrusions. mold flash or protrusions shall not exceed 0.006 (0.152) per side. 4. dimension obo does not include dambar protrusion. allowable dambar protrusion shall be 0.008 (0.203) maximum. dim a min max min max millimeters 0.370 0.390 9.39 9.91 inches a1 0.002 0.010 0.05 0.25 b 0.038 0.042 0.96 1.07 d 0.465 0.485 11.81 12.32 e 0.680 0.700 17.27 17.78 e1 0.465 0.485 11.81 12.32 e m 0.270 0.290 6.86 7.37 n 0.160 0.180 4.06 4.57 p 0.009 0.011 0.23 0.28 t 0.110 0.130 2.79 3.30 0.100 bsc 2.54 bsc f 0.240 0.260 6.10 6.60 k 0.115 0.135 2.92 3.43 l 0.040 0.060 1.02 1.52 f k m t ? gage detail g l a1 q .014 (0.35) plane 0 7 0 7 q style 1: pin 1. gnd 2. +vout 3. vs 4. vout 5. n/c 6. n/c 7. n/c 8. n/c style 2: pin 1. n/c 2. vs 3. gnd 4. vout 5. n/c 6. n/c 7. n/c 8. n/c f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3437 motorola sensor device data www.motorola.com/semiconductors package outline dimensions (continued) case 136801 issue o d e e/2 n e a m 0.004 (0.1) b c a e1 a b c 0.004 (0.1) a 0.006 (0.15) b c 8x b 2 places 4 tips detail g seating plane 8x p 1 4 8 5 notes: 1. controlling dimension: inch. 2. interpret dimensions and tolerances per asme y14.5m1994. 3. dimensions odo and oe1o do not include mold flash or protrusions. mold flash or protrusions shall not exceed 0.006 (0.152) per side. 4. dimension obo does not include dambar protrusion. allowable dambar protrusion shall be 0.008 (0.203) maximum. dim a min max min max millimeters 0.280 0.300 7.11 7.62 inches a1 0.002 0.010 0.05 0.25 b 0.038 0.042 0.96 1.07 d 0.465 0.485 11.81 12.32 e e1 0.465 0.485 11.81 12.32 e m 0.035 0.055 1.90 2.41 n 0.075 0.095 0.89 1.39 p 0.009 0.011 0.23 0.28 r 0.405 0.415 10.28 10.54 0.100 bsc 2.54 bsc f 0.240 0.260 6.10 6.60 k 0.115 0.135 2.92 3.43 l 0.040 0.060 1.02 1.52 f k m r ? gage detail g l a1 q .014 (0.35) plane 0 7 0 7 q style 1: pin 1. gnd 2. +vout 3. vs 4. vout 5. n/c 6. n/c 7. n/c 8. n/c style 2: pin 1. n/c 2. vs 3. gnd 4. vout 5. n/c 6. n/c 7. n/c 8. n/c t ? t 0.110 0.130 2.79 3.30 0.690 bsc 17.52 bsc f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3438 motorola sensor device data www.motorola.com/semiconductors package outline dimensions (continued) case 136901 issue o d e e/2 n e a m 0.004 (0.1) b c a e1 a b c 0.004 (0.1) a 0.008 (0.20) b c 8x b 2 places 4 tips detail g seating plane 8x p 1 4 8 5 notes: 1. controlling dimension: inch. 2. interpret dimensions and tolerances per asme y14.5m1994. 3. dimensions odo and oe1o do not include mold flash or protrusions. mold flash or protrusions shall not exceed 0.006 (0.152) per side. 4. dimension obo does not include dambar protrusion. allowable dambar protrusion shall be 0.008 (0.203) maximum. dim a min max min max millimeters 0.300 0.330 7.11 7.62 inches a1 0.002 0.010 0.05 0.25 b 0.038 0.042 0.96 1.07 d 0.465 0.485 11.81 12.32 e e1 0.465 0.485 11.81 12.32 e m 0.270 0.290 6.86 7.36 n 0.080 0.090 2.03 2.28 p 0.009 0.011 0.23 0.28 t 0.115 0.125 2.92 3.17 0.100 bsc 2.54 bsc f 0.245 0.255 6.22 6.47 k 0.120 0.130 3.05 3.30 l 0.061 0.071 1.55 1.80 f k m gage detail g l a1 q .014 (0.35) plane 0 7 0 7 q t ? 0.717 bsc 18.21 bsc f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3439 motorola sensor device data www.motorola.com/semiconductors reference tables flow equivalents 1 cu. ft./hr. 1 cu. ft./min. 1 cc/min. 1 cc/hr. 0.0166 0.4719 28.316 471.947 28317 0.1247 7.481 cu. ft./min lpm lph cc/min. cc/hr. gal/min. gal/hr. 60 28.316 1699 28317 1,699,011 7.481 448.831 cu. ft./min lpm lph cc/min. cc/hr. gal/min. gal/hr. 60 0.000035 0.0021 0.001 0.06 0.00026 0.0159 cc/hr. cu. ft./min cu. ft./hr. lpm lph gal/min. gal/hr. 0.0167 0.0000005 0.00003 0.000017 0.001 0.000004 0.00026 cc/min. cu. ft./min. cu. ft./hr. lpm lph gal/min. gal/hr. 1 lpm 1 lph 1 gal/min. 1 gal/hr. lph cu. ft./min. cu. ft./hr. cc/min. cc/hr. gal/min. gal/hr. 60 0.035 2.1189 1000 60,002 0.264 15.851 0.0166 0.00059 0.035 16.667 1000 0.004 0.264 lpm cu. ft./min. cu. ft./hr. cc/min. cc/hr. gal/min. gal/hr. 60 0.1337 8.021 3.785 227.118 3,785.412 227,125 gal/hr. cu. ft./min. cu. ft./hr. lpm lph cc/min. cc/hr. 0.0167 0.002 0.1337 0.063 3.785 63.069 3785 gal/min. cu. ft./min. cu. ft./hr. lpm lph cc/min. cc/hr. airspeed knots inches of mercury knots inches of mercury 8 60 8 80 100 110 120 130 140 150 175 200 225 250 275 300 325 350 375 0.1727 0.3075 0.4814 0.5832 0.6950 0.8168 0.9488 1.0910 1.4918 1.9589 2.4943 3.1002 3.7792 4.5343 5.3687 6.2859 7.2900 8, 400 8, 425 8, 450 8, 475 8, 500 8, 525 8, 550 8, 575 8, 600 8, 650 8, 700 8, 750 8, 800 8, 850 8, 900 1,000 8 8.3850 8 9.5758 10.8675 12.2654 13.7756 15.4045 17.1590 19.0465 21.0749 25.5893 30.7642 36.5662 42.9378 49.8423 57.2554 73.5454 altitude (feet) equivalent pressure (inches of mercury) altitude (feet) equivalent pressure (inches of mercury) 1,000 900 0 500 1,000 1,500 2,000 3,000 4,000 6,000 8,000 10,000 12,000 31.0185 30.9073 29.9213 29.3846 28.8557 28.3345 27.8210 26.8167 25.8418 23.9782 22.2250 20.5770 19.0294 14,000 16,000 18,000 20,000 22,000 25,000 30,000 35,000 40,000 45,000 49,900 50,000 17.5774 16.2164 14.9421 13.7501 12.6363 11.1035 8.88544 7.04062 5.53802 4.35488 3.44112 3.42466 (est) f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3440 motorola sensor device data www.motorola.com/semiconductors reference tables (continued) conversion table for common units of pressure kilopascals mm hg millibars inches h 2 o psi 1 atm 101.325 760.000 1013.25 406.795 14.6960 1 kilopascal 1.00000 7.50062 10.0000 4.01475 0.145038 1 mm hg 0.133322 1.00000 1.33322 0.535257 0.0193368 1 millibar 0.100000 0.750062 1.00000 0.401475 0.0145038 1 inch h 2 o 0.249081 1.86826 2.49081 1.00000 0.0361 1 psi 6.89473 51.7148 68.9473 27.6807 1.00000 1 hectopascal 0.100000 0.75006 1.00000 0.401475 0.0145038 1 cm h 2 o 0.09806 0.7355 9.8 x 10 7 0.3937 0.014223 quick conversion chart for common units of pressure kilopascals inches h 2 o millibars mm hg psi 0 20 40 60 80 100 120 140 160 180 200 0 100 200 300 400 500 600 700 800 0 200 400 600 800 1000 1200 1400 1600 1800 2000 0 200 400 600 800 1000 1200 1400 1600 0 5 10 15 20 25 30 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3441 motorola sensor device data www.motorola.com/semiconductors mounting and handling suggestions custom port adaptor installation techniques the motorola mpx silicon pressure sensor is available in a basic chip carrier cell which is adaptable for attachment to customer specific housings/ports (case 344 for 4-pin devices and case 867 for 6-pin devices). the basic cell has chamfered shoulders on both sides which will accept an o- ring such as parker seal's silicone o-ring (p/n#2-015-s-469-40). refer to figure 1 for the recommended o-ring to sensor cell interface dimensions. the sensor cell may also be glued directly to a custom housing or port using many commercial grade epoxies or rtv adhesives which adhere to grade valox 420, reinforced polyester resin plastic polysulfone (mpx2040d only). the epoxy should be dispensed in a continuous bead around the cell-to-port interface shoulder. refer to figure 2. care must be taken to avoid gaps or voids in the adhesive bead to help ensure that a complete seal is made when the cell is joined to the port. after cure, a simple test for gross leaks should be performed to ensure the integrity of the cell to port bond. submerging the device in water for 5 seconds with full rated pressure applied to the port nozzle and checking for air bubbles will provide a good indication. be sure device is thoroughly dried after this test. figure 2. adhesive bead standard port attach connection motorola also offers standard port options designed to accept readily available silicone, vinyl, nylon or polyethylene tubing for the pressure connection. the inside dimension of the tubing selected should provide a snug fit over the port nozzle. dimensions of the ports may be found in the case outline drawings. installation and removal of tubing from the port nozzle must be parallel to the nozzle to avoid undue stress which may break the nozzle from the port base. whether sensors are used with motorola's standard ports or customer specific housings, care must be taken to ensure that force is uniformly distributed to the package or offset errors may be induced. electrical connection the mpx series pressure sensor is designed to be installed on a printed circuit board (standard 0.100 lead spacing) or to accept an appropriate connector if installed on a baseplate. the leads of the sensor may be formed at right angles for assembly to the circuit board, but one must ensure that proper leadform techniques and tools are employed. hand or aneedlenoseo pliers should never be used for leadforming unless they are specifically designed for that purpose. industrial leadform tooling is available from various compan- ies including janesville tool & manufacturing (608-868-4925). refer to figure 3 for the recommended leadform technique. it is also important that once the leads are formed, they should not be straightened and reformed without expecting reduced durability. the recommended connector for off-circuit board applications may be supplied by jst corp. (1-800-292-4243) in mount prospect, il. the part numbers for the housing and pins are: 4 pin housing: smp-04v-bc 6 pin housing: smp-06v-bc pin: shf-01t-0.8ss the crimp tool part number is: yc12. figure 1. .114 .047 0 .125 .075 .037r 0 .021 .210 cell figure 3. leadforming top clamp area bottom clamp area leads should be securely clamped top and bottom in the area between the plastic body and the form being sure that no stress is being put on plastic body. the area between dotted lines represents surfaces to be clamped. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3442 motorola sensor device data www.motorola.com/semiconductors standard warranty clause seller warrants that its products sold hereunder will at the time of shipment be free from defects in material and workmanship, and will conform to seller's approved specifications. if products are not as warranted, seller shall, at its option and as buyer's exclusive remedy, either refund the purchase price, or repair, or replace the product, provided proof of purchase and written notice of nonconformance are received within the applicable periods noted below and provided said nonconforming products are, with seller's written authorization, returned in protected shipping containers fob seller's plant within thirty (30) days after expiration of the warranty period unless otherwise specified herein. if product does not conform to this warranty, seller will pay for the reasonable cost of transporting the goods to and from seller's plant. this warranty shall not apply to any products seller determines have been, by buyer or otherwise, subjected to improper testing, or have been the subject of mishandling or misuse. this warranty extends to buyer only and may be invoked by buyer only for its customers. seller will not accept warranty returns directly from buyer's customers or users of buyer's products. this warranty is in lieu of all other warranties whether express, implied or statutory including implied warranties of merchantability or fitness for a particular purpose. seller's warranty shall not be enlarged, and no obligation or liability shall arise out of seller's rendering of technical advice and/or assistance. a. time periods, products, exceptions and other restrictions applicable to the above warranty are: (1) unless otherwise stated herein, products are warranted for a period of one (1) year from date of shipment. (2) device chips/wafers. seller warrants that device chips or wafers have, at shipment, been subjected to electrical test/probe and visual inspection. warranty shall apply to products returned to seller within ninety (90) days from date of shipment. this warranty shall not apply to any chips or wafers improperly removed from their original shipping container and/or subjected to testing or operational procedures not approved by seller in writing. b. development products and licensed programs are licensed on an aas iso basis. in no event shall seller be liable for any incidental or consequential damages. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3443 motorola sensor device data www.motorola.com/semiconductors glossary of terms absolute pressure sensor a sensor which measures input pressure in relation to a zero pressure (a total vacuum on one side of the diaphragm) reference. analog output an electrical output from a sensor that changes proportionately with any change in input pressure. accuracy e also see pressure error a comparison of the actual output signal of a device to the true value of the input pressure. the various errors (such as linearity, hysteresis, repeatability and temperature shift) attributing to the accuracy of a device are usually expressed as a percent of full scale output (fso). altimetric pressure transducer a barometric pressure transducer used to determine altitude from the pressure-altitude profile. barometric pressure transducer an absolute pressure sensor that measures the local ambient atmospheric pressure. burst pressure the maximum pressure that can be applied to a transducer without rupture of either the sensing ele- ment or transducer case. calibration a process of modifying sensor output to improve output accuracy. chip a die (unpackaged semiconductor device) cut from a silicon wafer, incorporating semiconductor cir- cuit elements such as resistors, diodes, transistors, and/or capacitors. compensation added circuitry or materials designed to counteract known sources of error. diaphragm the membrane of material that remains after etching a cavity into the silicon sensing chip. changes in input pressure cause the diaphragm to deflect. differential pressure sensor a sensor which is designed to accept simultaneously two independent pressure sources. the output is proportional to the pressure difference between the two sources. diffusion a thermochemical process whereby controlled impurities are introduced into the silicon to define the piezoresistor. compared to ion implantation, it has two major disadvantages: 1) the maximum impuri- ty concentration occurs at the surface of the silicon rendering it subject to surface contamination, and making it nearly impossible to produce buried piezoresistors; 2) control over impurity concentra- tions and levels is about one thousand times poorer than obtained with ion implantation. drift an undesired change in output over a period of time, with constant input pressure applied. end point straight line fit motorola's method of defining linearity. the maximum deviation of any data point on a sensor output curve from a straight line drawn between the end data points on that output curve. error the algebraic difference between the indicated value and the true value of the input pressure. usually expressed in percent of full scale span, sometimes expressed in percent of the sensor output reading. error band the band of maximum deviations of the output values from a specified reference line or curve due to those causes attributable to the sensor. usually expressed as a % of full scale output.o the error band should be specified as applicable over at least two calibration cycles, so as to include repeatability, and verified accordingly. excitation voltage (current) e see supply voltage (current) the external electrical voltage and/or current applied to a sensor for its proper operation (often referred to as the supply circuit or voltage). motorola specifies constant voltage operation only. full scale output the output at full scale pressure at a specified supply voltage. this signal is the sum of the offset signal plus the full scale span. full scale span the change in output over the operating pressure range at a specified supply voltage. the span of a device is the output voltage variation given between zero differential pressure and any given pressure. full scale span is the output variation between zero differential pressure and when the maximum recommended operating pressure is applied. hysteresis e also see pressure hysteresis and temperature hysteresis hysteresis refers to a transducer's ability to reproduce the same output for the same input, regardless of whether the input is increasing or decreasing. pressure hysteresis is measured at a constant temperature while temperature hysteresis is measured at a constant pressure in the operating pressure range. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3444 motorola sensor device data www.motorola.com/semiconductors glossary of terms (continued) input impedance (resistance) the impedance (resistance) measured between the positive and negative (ground) input terminals at a specified frequency with the output terminals open. for motorola x-ducer, this is a resistance measurement only. ion implantation a process whereby impurity ions are accelerated to a specific energy level and impinged upon the silicon wafer. the energy level determines the depth to which the impurity ions penetrate the silicon. impingement time determines the impurity concentration. thus, it is possible to independently control these parameters, and buried piezoresistors are easily produced. ion implantation is increasingly used throughout the semiconductor industry to provide a variety of products with improved performance over those produced by diffusion. laser trimming (automated) a method for adjusting the value of thin film resistors using a computer-controlled laser system. leakage rate the rate at which a fluid is permitted or determined to leak through a seal. the type of fluid, the differential pressure across the seal, the direction of leakage, and the location of the seal must be specified. linearity error the maximum deviation of the output from a straight line relationship with pressure over the operating pressure range, the type of straight line relationship (end point, least square approximation, etc.) should be specified. load impedance the impedance presented to the output terminals of a sensor by the associated external circuitry. null the condition when the pressure on each side of the sensing diaphragm is equal. null offset the electrical output present, when the pressure sensor is at null. null temperature shift the change in null output value due to a change in temperature. null output see zero pressure offset offset see zero pressure offset operating pressure range the range of pressures between minimum and maximum pressures at which the output will meet the specified operating characteristics. operating temperature range the range of temperature between minimum and maximum temperature at which the output will meet the specified operating characteristics. output impedance the impedance measured between the positive and negative (ground) output terminals at a speci- fied frequency with the input open. overpressure the maximum specified pressure which may be applied to the sensing element of a sensor without causing a permanent change in the output characteristics. piezoresistance a resistive element that changes resistance relative to the applied stress it experiences (e.g., strain gauge). pressure error the maximum difference between the true pressure and the pressure inferred from the output for any pressure in the operating pressure range. pressure hysteresis the difference in the output at any given pressure in the operating pressure range when this pressure is approached from the minimum operating pressure and when approached from the maximum operating pressure at room temperature. pressure range e also see operating pressure range the pressure limits over which the pressure sensor is calibrated or specified. pressure sensor a device that converts an input pressure into an electrical output. proof pressure see overpressure ratiometric ratiometricity refers to the ability of the transducer to maintain a constant sensitivity, at a constant pressure, over a range of supply voltage values. ratiometric (ratiometricity error) at a given supply voltage, sensor output is a proportion of that supply voltage. ratiometricity error is the change in this proportion resulting from any change to the supply voltage. usually expressed as a percent of full scale output. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3445 motorola sensor device data www.motorola.com/semiconductors glossary of terms (continued) range see operating pressure range repeatability the maximum change in output under fixed operating conditions over a specified period of time. resolution the maximum change in pressure required to give a specified change in the output. response time the time required for the incremental change in the output to go from 10% to 90% of its final value when subjected to a specified step change in pressure. room conditions ambient environmental conditions under which sensors most commonly operate. sensing element that part of a sensor which responds directly to changes in input pressure. sensitivity the change in output per unit change in pressure for a specified supply voltage or current. sensitivity shift a change in sensitivity resulting from an environmental change such as temperature. stability the maximum difference in the output at any pressure in the operating pressure range when this pressure is applied consecutively under the same conditions and from the same direction. storage temperature range the range of temperature between minimum and maximum which can be applied without causing the sensor to fail to meet the specified operating characteristics. strain gauge a sensing device providing a change in electrical resistance proportional to the level of applied stress. supply voltage (current) the voltage (current) applied to the positive and negative (ground) input terminals. temperature coefficient of full scale span the percent change in full scale span per unit change in temperature relative to the full scale span at a specified temperature. temperature coefficient of resistance the percent change in the dc input impedance per unit change in temperature relative to the dc input impedance at a specified temperature. temperature error the maximum change in output at any pressure in the operating pressure range when the tempera- ture is changed over a specified temperature range. temperature hysteresis the difference in output at any temperature in the operating temperature range when the tempera- ture is approached from the minimum operating temperature and when approached from the maximum operating temperature with zero pressure applied. thermal offset shift see temperature coefficient of offset thermal span shift see temperature coefficient of full scale span thermal zero shift see temperature coefficient of offset thin film a technology using vacuum deposition of conductors and dielectric materials onto a substrate (frequently silicon) to form an electrical circuit. vacuum a perfect vacuum is the absence of gaseous fluid. zero pressure offset the output at zero pressure (absolute or differential, depending on the device type) for a speci- fied supply voltage or current. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
3446 motorola sensor device data www.motorola.com/semiconductors symbols, terms and definitions the following are the most commonly used letter symbols, terms and definitions associated with solid state silicon pressure sensors. p burst burst pressure the maximum pressure that can be applied to a transducer without rupture of either the sensing element or transducer case. i o supply current the current drawn by the sensor from the voltage source. i o+ output source current the current sourcing capability of the pressure sensor. kpa kilopascals unit of pressure. 1 kpa = 0.145038 psi. e linearity the maximum deviation of the output from a straight line relationship with pressure over the operating pressure range, the type of straight line relationship (end point, least square approximation, etc.) should be specified. mm hg millimeters of mercury unit of pressure. 1 mmhg = 0.0193368 psi. p max overpressure the maximum specified pressure which may be applied to the sensing element without causing a permanent change in the output characteristics. p op operating pressure range the range of pressures between minimum and maximum temperature at which the output will meet the specified operating characteristics. e pressure hysteresis the difference in the output at any given pressure in the operating pressure range when this pressure is approached from the minimum operating pressure and when approached from the maximum operating pressure at room temperature. psi pounds per square inch unit of pressure. 1 psi = 6.89473 kpa. e repeatability the maximum change in output under fixed operating conditions over a specified period of time. r o input resistance the resistance measured between the positive and negative input terminals at a specified frequency with the output terminals open. t a operating temperature the temperature range over which the device may safely operate. tcr temperature coefficient of resistance the percent change in the dc input impedance per unit change in temperature relative to the dc input impedance at a specified temperature (typically +25 c). tcv fss temperature coefficient of full scale span the percent change in full scale span per unit change in temperature relative to the full scale span at a specified temperature (typically +25 c). tcv off temperature coefficient of offset the percent change in offset per unit change in temperature relative to the offset at a speci- fied temperature (typically +25 c). t stg storage temperature the temperature range at which the device, without any power applied, may be stored. t r response time the time required for the incremental change in the output to go from 10% to 90% of its final value when subjected to a specified step change in pressure. e temperature hysteresis the difference in output at any temperature in the operating temperature range when the temperature is approached from the minimum operating temperature and when approached from the maximum operating temperature with zero pressure applied. v fss full scale span voltage the change in output over the operating pressure range at a specified supply voltage. v off offset voltage the output with zero differential pressure applied for a specified supply voltage or current. v s supply voltage dc the dc excitation voltage applied to the sensor. for precise circuit operation, a regulated supply should be used. v s max maximum supply voltage the maximum supply voltage that may be applied to a circuit or connected to the sensor. z in input impedance the resistance measured between the positive and negative input terminals at a specified frequency with the output terminals open. for motorola x-ducer, this is a resistance measure- ment only. z out output impedance the resistance measured between the positive and negative output terminals at a speci- fied frequency with the input terminals open. d v/ d p sensitivity the change in output per unit change in pressure for a specified supply voltage. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
41 motorola sensor device data www.motorola.com/semiconductors
section four motorola's safety and alarm integrated circuits (ic's) are low power, cmos devices designed to meet a wide range of smoke detector applications at very competitive prices. moto- rola has been producing both photoelectric and ionization safety and alarm ic's for more than 20 years. found in con- sumer and commercial applications worldwide, these inte- grated circuits can be operated using a battery or ac power. in addition, these devices are designed to be used in stand alone units or as an interconnected system of up to 40 units. all of motorola's safety and alarm ic's have component recog- nition from underwriter's laboratories and the newest devices meet the nfpa's new temporal new tone horn pattern. mini selector guide 42 . . . . . . . . . . . . . . . . . . . . . . . . . data sheets mc144671 4 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mc14468 4 9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mc14578 4 15 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mc14600 419 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mc145010 4 24 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mc145011 4 34 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mc145012 4 44 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mc145017 454 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mc145018 4 60 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . application notes an1690 4 66 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . an4009 470 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . case outlines 472 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
42 motorola sensor device data www.motorola.com/semiconductors mini selector guide safety and alarm integrated circuits smoke ion product operating voltage (v) horn tone interconnectable primary power source ordering suffix note mc14467 6 to 12 continuous old tone 4/6 no dc p1 mc14468 6 to 12 continuous old tone 4/6 yes ac/dc p mc145017 6 to 12 temporal new tone nfpa tone no dc p mc145018 6 to 12 temporal new tone nfpa tone yes ac/dc p smoke photo product operating voltage (v) horn tone interconnectable primary power source ordering suffix note mc145010 6 to 12 continuous old tone 4/6 yes ac/dc p, dw, dwr2 mc145011 6 to 12 continuous old tone 4/6 yes ac p, dw, dwr2 mc145012 6 to 12 temporal new tone nfpa tone yes ac/dc p, dw, dwr2 comparator product operating voltage (v) description horn modulation primary power source ordering suffix note mc14578 3.5 to 14 micropower comparator plus voltage follower no horn driver ac/dc p general alarm product operating voltage (v) description horn tone(ms) primary power source ordering suffix note mc14600 6.0 to 12 alarm detection, horn driver, low battery detection, led driver continuous old tone 4/6 ac/dc p, dw, dwr2 note: p or p1 = 16pin dip, dw = soic 16pin, dwr2 = soic 16pin tape & reel f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
43 motorola sensor device data www.motorola.com/semiconductors lowpower cmos

the mc144671, when used with an ionization chamber and a small number of external components, will detect smoke. when smoke is sensed, an alarm is sounded via an external piezoelectric transducer and internal drivers. this circuit is designed to operate in smoke detector systems that comply with ul217 and ul268 specifications. ? ionization type with onchip fet input comparator ? piezoelectric horn driver ? guard outputs on both sides of detect input ? inputproduction diodes on the detect input ? lowbattery trip point, internally set, can be altered via external resistor ? detect threshold, internally set, can be altered via external resistor ? pulse testing for low battery uses led for battery loading ? comparator outputs for detect and low battery ? internal reverse battery protection maximum ratings* (voltages referenced to v ss ) rating symbol value unit dc supply voltage v dd 0.5 to + 15 v input voltage, all inputs except pin 8 v in 0.25 to v dd + 0.25 v dc current drain per input pin, except pin 15 = 1 ma i 10 ma dc current drain per output pin i 30 ma operating temperature range t a 10 to +60 c storage temperature range t stg 55 to + 125 c reverse battery time t rb 5.0 s * maximum ratings are those values beyond which damage to the device may occur. this device contains circuitry to protect the inputs against damage due to high static voltages or electric fields; however, it is advised that normal precautions be taken to avoid application of any voltage higher than maximum rated voltages to this high impedance circuit. for proper operation it is recommended that except for pin 8, v in and v out be constrained to the range v ss (v in or v out ) v dd . for pin 8, refer to the electrical characteristics. semiconductor technical data p suffix plastic dip case 64808 pin assignment (16 pin dip) 16 15 14 13 12 11 10 9 1 2 3 4 5 6 7 8 detect comp. out n/c low v set low v comp. out led v dd timing resistor feedback guard hiz detect input guard loz sensitivity set osc capacitor silver brass v ss ordering information mc14467p1 plastic dip 1 16 rev 3 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
44 motorola sensor device data www.motorola.com/semiconductors recommended operating conditions (voltages referenced to v ss ) parameter symbol value unit supply voltage v dd 9.0 v timing capacitor e 0.1 m f timing resistor e 8.2 m w battery load (resistor or led) e 10 ma electrical characteristics (voltages referenced to v ss , t a = 25 c) characteristic symbol v dd v dc min typ# max unit operating voltage v dd e 6.0 e 12 v output voltage piezoelectric horn drivers (i oh = 16 ma) comparators (i oh = 30 m a) piezoelectric horn drivers (i ol = +16 ma) comparators (i ol = +30 m a) v oh v ol 7.2 9.0 7.2 9.0 6.3 8.5 e e e 8.8 e 0.1 e e 0.9 0.5 v v output voltage e led driver, i ol = 10 ma v ol 7.2 e e 3.0 v output impedance, active guard pin 14 pin 16 loz hiz 9.0 9.0 e e e e 10 1000 k w operating current (r bias = 8.2 m w ) i dd 9.0 12.0 e e 5.0 e 9.0 12.0 m a input current e detect (40% r.h.) i in 9.0 e e 1.0 pa internal set voltage low battery sensitivity v low v set 9.0 e 7.2 47 e 50 7.8 53 v %v dd hysteresis v hys 9.0 75 100 150 mv offset voltage (measured at vin = vdd/2) active guard detect comparator v os 9.0 9.0 e e e e 100 50 mv input voltage range, pin 8 v in e vss 10 e vdd + 10 v input capacitance c in e e 5.0 e pf common mode voltage range, pin 15 v cm e 0.6 e vdd 2 v # data labelled atyp'' is not to be used for design purposes but is intended as an indication of the ic's potential performance . f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
45 motorola sensor device data www.motorola.com/semiconductors timing parameters (c = 0.1 m f, r bias = 8.2 m w , v dd = 9.0 v, t a = 25 c, see figure 6) characteristics symbol min typ# max units oscillator period no smoke smoke t ci 1.34 32 1.67 40 2.0 48 s ms oscillator rise time t r 8.0 10 12 ms horn output on time (during smoke) off time pw on pw off 120 60 160 80 208 104 ms ms led output between pulses on time t led pw on 32 8.0 40 10 48 12 s ms horn output on time (during low battery) between pulses t on t off 8.0 32 10 40 12 48 ms s # data labelled atyp'' is not to be used for design purposes but is intended as an indication of the ic's potential performance . figure 1. block diagram + v dd latch low battery comp. oscillator timer latch + v dd 80 k 3 1045 k 7 12 1 13 1125 k + 15 detect input 14 loz active guard 16 hiz v dd 4 v dd 8 piezoelectric horn driver 11 10 5 led driver v dd 6 9 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
46 motorola sensor device data www.motorola.com/semiconductors figure 2. typical led output iv characteristic figure 3. typical comparator output iv characteristic figure 4. typical p horn driver output iv characteristic 0 1234 56 7 8910 0.1 1.0 10.0 100 . 0 t a = 25 c v ds , drain to source voltage (vdc) v dd = 7.2 vdc v dd = 9.0 vdc 012345678910 1.0 10.0 100.0 1000.0 d i , drain current (ma) t a = 25 c v ds , drain to source voltage (vdc) pch source current v dd = 7.2 vdc v dd = 9.0 vdc 012345678910 1.0 10.0 100.0 1000.0 d i , drain current (ma) t a = 25 c v ds , drain to source voltage (vdc) nch sink current v dd = 7.2 vdc v dd = 9.0 vdc 012 34 56 78910 0.01 0.1 1.0 10 . 0 d i , drain current (ma) t a = 25 c v ds , drain to source voltage (vdc) pch source and nch sink current v dd = 9.0 vdc or 7.2 vdc d i , drain current (ma) f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
47 motorola sensor device data www.motorola.com/semiconductors device operation timing the internal oscillator of the mc144671 operates with a period of 1.67 seconds during nosmoke conditions. each 1.67 seconds, internal power is applied to the entire ic and a check is made for smoke, except during led pulse, low bat- tery alarm chirp, or horn modulation (in smoke). every 24 clock cycles a check is made for low battery by comparing v dd to an internal zener voltage. since very small currents are used in the oscillator, the oscillator capacitor should be of a low leakage type. detect circuitry if smoke is detected, the oscillator period becomes 40 ms and the piezoelectric horn oscillator circuit is enabled. the horn output is modulated 160 ms on, 80 ms off. during the off time, smoke is again checked and will inhibit further horn out- put if no smoke is sensed. during smoke conditions the low battery alarm is inhibited, but the led pulses at a 1.0 hz rate. an active guard is provided on both pins adjacent to the detect input. the voltage at these pins will be within 100 mv of the input signal. this will keep surface leakage currents to a minimum and provide a method of measuring the input volt- age without loading the ionization chamber. the active guard op amp is not power strobed and thus gives constant protec- tion from surface leakage currents. pin 15 (the detect input) has internal diode protection against static damage. sensitivity/low battery thresholds both the sensitivity threshold and the low battery voltage levels are set internally by a common voltage divider (please see figure 1) connected between v dd and v ss . these volt- ages can be altered by external resistors connected from pins 3 or 13 to either v dd or v ss . there will be a slight inter- action here due to the common voltage divider network. the sensitivity threshold can also be set by adjusting the smoke chamber ionization source. test mode since the internal op amps and comparators are power strobed, adjustments for sensitivity or low battery level could be difficult and/or timeconsuming. by forcing pin 12 to v ss , the power strobing is bypassed and the outputs, pins 1 and 4, constantly show smoke/no smoke and good battery/low battery, respectively. pin 1 = v dd for smoke and pin 4 = v dd for low battery. in this mode and during the 10 ms power strobe, chip current rises to approximately 50 m a. led pulse the 9volt battery level is checked every 40 seconds dur- ing the led pulse. the battery is loaded via a 10 ma pulse for 10 ms. if the led is not used, it should be replaced with an equivalent resistor such that the battery loading remains at 10 ma. hysteresis when smoke is detected, the resistor/divider network that sets sensitivity is altered to increase sensitivity. this yields approximately 100 mv of hysteresis and reduces false triggering. figure 5. typical application as ionization smoke detector mc144671 116 2 3 4 5 6 7 8 15 14 13 12 11 10 9 330 w 8.2 m w + 9 v 0.1 m f 1.5 m w * 0.001* m f 220 k w * 0.1 m f 1 m 1 m test *note: component values may change depending on type of piezoelectric horn used. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
48 motorola sensor device data www.motorola.com/semiconductors figure 6. timing diagram hysteresis (internal) (pin 13 ) (pin 14) detect out (pin 1) low battery out (pin 4) sample (internal) smoke horn (pin 10 and 11) led (pin 5) oscillator (pin 12) standby smoke/no low battery smoke/low battery no smoke/ no low battery no smoke/low battery 40 ms 10 ms 1.67 s 24 clock cycles (0.96 s) 24 clock cycles (40s) 24 clock cycles 6 clock suppressed chirp battery test (note 3) (note 3) (note 1) cycles (10.0s) notes: 1. horn modulation is selfcompleting. when going from smoke to no smoke, the alarm condition will terminate only when horn is o ff. 2. comparators are strobed on once per clock cycle (1.67 s for no smoke, 40 ms for smoke). 3. low battery comparator information is latched only during led pulse. 4. 100 mv pp swing. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
49 motorola sensor device data www.motorola.com/semiconductors lowpower cmos the mc14468, when used with an ionization chamber and a small number of external components, will detect smoke. when smoke is sensed, an alarm is sounded via an external piezoelectric transducer and internal drivers. this circuit is designed to operate in smoke detector systems that comply with ul217 and ul268 specifications. ? ionization type with onchip fet input comparator ? piezoelectric horn driver ? guard outputs on both sides of detect input ? inputproduction diodes on the detect input ? lowbattery trip point, internally set, can be altered via external resistor ? detect threshold, internally set, can be altered via external resistor ? pulse testing for low battery uses led for battery loading ? comparator output for detect ? internal reverse battery protection ? strobe output for external trim resistors ? i/o pin allows up to 40 units to be connected for common signaling ? poweron reset prevents false alarms on battery change maximum ratings* (voltages referenced to v ss ) rating symbol value unit dc supply voltage v dd 0.5 to + 15 v input voltage, all inputs except pin 8 v in 0.25 to v dd + 0.25 v dc current drain per input pin, except pin 15 = 1 ma i 10 ma dc current drain per output pin i 30 ma operating temperature range t a 10 to + 60 c storage temperature range t stg 55 to + 125 c reverse battery time t rb 5.0 s * maximum ratings are those values beyond which damage to the device may occur. this device contains circuitry to protect the inputs against damage due to high static voltages or electric fields; however, it is advised that normal precautions be taken to avoid application of any voltage higher than maximum rated voltages to this high impedance circuit. for proper operation it is recommended that v in and v out be constrained to the range v ss (v in or v out ) v dd .
semiconductor technical data p suffix plastic dip case 64808 pin assignment (16 pin dip) 16 15 14 13 12 11 10 9 1 2 3 4 5 6 7 8 detect comp. out i/o low v set strobe out led v dd timing resistor feedback guard hiz detect input guard loz sensitivity set osc capacitor silver brass v ss ordering information mc14468p plastic dip 1 16 rev 3 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
410 motorola sensor device data www.motorola.com/semiconductors recommended operating conditions (voltages referenced to v ss ) parameter symbol value unit supply voltage v dd 9.0 v timing capacitor e 0.1 m f timing resistor e 8.2 m w battery load (resistor or led) e 10 ma electrical characteristics (t a = 25 c) characteristic symbol v dd v dc min typ# max unit operating voltage v dd e 6.0 e 12 v output voltage piezoelectric horn drivers (i oh = 16 ma) comparators (i oh = 30 m a) piezoelectric horn drivers (i ol = +16 ma) comparators (i ol = +30 m a) v oh v ol 7.2 9.0 7.2 9.0 6.3 8.5 e e e 8.8 e 0.1 e e 0.9 0.5 v v output voltage e led driver, i ol = 10 ma v ol 7.2 e e 3.0 v output impedance, active guard pin 14 pin 16 loz hiz 9.0 9.0 e e e e 10 1000 k w operating current (r bias = 8.2 m w ) i dd 9.0 12.0 e e 5.0 e 9.0 12.0 m a input current e detect (40% r.h.) i in 9.0 e e 1.0 pa input current, pin 8 i in 9.0 e e 0.1 m a input current @ 50 c, pin 15 i in e e e 6.0 pa internal set voltage low battery sensitivity v low v set 9.0 e 7.2 47 e 50 7.8 53 v %v dd hysteresis v hys 9.0 75 100 150 mv offset voltage (measured at vin = vdd/2) active guard detect comparator v os 9.0 9.0 e e e e 100 50 mv input voltage range, pin 8 v in e vss 10 e vdd + 10 v input capacitance c in e e 5.0 e pf common mode voltage range, pin 15 v cm e 0.6 e vdd 2 v i/o current, pin 2 input, v ih = vdd 2 output, v oh = vdd 2 i ih i oh e e 25 4.0 e e 100 16 m a ma # data labelled atyp'' is not to be used for design purposes but is intended as an indication of the ic's potential performance . f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
411 motorola sensor device data www.motorola.com/semiconductors timing parameters (c = 0.1 m f, r bias = 8.2 m w , v dd = 9.0 v, t a = 25 c, see figure 6) characteristics symbol min typ# max units oscillator period no smoke smoke t ci 1.34 32 1.67 40 2.0 48 s ms oscillator rise time t r 8.0 10 12 ms horn output on time (during smoke) off time pw on pw off 120 60 160 80 208 104 ms ms led output between pulses on time t led pw on 32 8.0 40 10 48 12 s ms horn output on time (during low battery) between pulses t on t off 8.0 32 10 40 12 48 ms s # data labelled atyp'' is not to be used for design purposes but is intended as an indication of the ic's potential performance . figure 1. block diagram + v dd low battery comparator poweron reset + v dd 45 k 3 280 k 7 12 13 325 k + 15 detect input 14 loz 16 hiz v dd v dd 8 11 10 5 low v set 1 detect comparator out alarm logic detect comparator i/o 2 osc and timing silver brass guard amp strobe out 4 led feedback to other units v dd = pin 6 v ss = pin 9 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
412 motorola sensor device data www.motorola.com/semiconductors figure 2. typical led output iv characteristic figure 3. typical comparator output iv characteristic figure 4. typical p horn driver output iv characteristic 0 1234 56 7 8910 0.1 1.0 10.0 100 . 0 t a = 25 c v ds , drain to source voltage (vdc) v dd = 7.2 vdc v dd = 9.0 vdc 012345678910 1.0 10.0 100.0 1000.0 d i , drain current (ma) t a = 25 c v ds , drain to source voltage (vdc) pch source current v dd = 7.2 vdc v dd = 9.0 vdc 012345678910 1.0 10.0 100.0 1000.0 d i , drain current (ma) t a = 25 c v ds , drain to source voltage (vdc) nch sink current v dd = 7.2 vdc v dd = 9.0 vdc 012 34 56 78910 0.01 0.1 1.0 10 . 0 d i , drain current (ma) t a = 25 c v ds , drain to source voltage (vdc) pch source and nch sink current v dd = 9.0 vdc or 7.2 vdc d i , drain current (ma) f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
413 motorola sensor device data www.motorola.com/semiconductors device operation timing the internal oscillator of the mc14468 operates with a period of 1.67 seconds during nosmoke conditions. each 1.67 seconds, internal power is applied to the entire ic and a check is made for smoke, except during led pulse, low bat- tery alarm chirp, or horn modulation (in smoke). every 24 clock cycles a check is made for low battery by comparing v dd to an internal zener voltage. since very small currents are used in the oscillator, the oscillator capacitor should be of a low leakage type. detect circuitry if smoke is detected, the oscillator period becomes 40 ms and the piezoelectric horn oscillator circuit is enabled. the horn output is modulated 160 ms on, 80 ms off. during the off time, smoke is again checked and will inhibit further horn out- put if no smoke is sensed. during local smoke conditions the low battery alarm is inhibited, but the led pulses at a 1.0 hz rate. in remote smoke, the led is inhibited as well. an active guard is provided on both pins adjacent to the detect input. the voltage at these pins will be within 100 mv of the input signal. this will keep surface leakage currents to a minimum and provide a method of measuring the input volt- age without loading the ionization chamber. the active guard op amp is not power strobed and thus gives constant protec- tion from surface leakage currents. pin 15 (the detect input) has internal diode protection against static damage. interconnect the i/o (pin 2), in combination with v ss , is used to inter- connect up to 40 remote units for common signaling. a local smoke condition activates a current limited output driver, thereby signaling remote smoke to interconnected units. a small current sink improves noise immunity during non smoke conditions. remote units at lower voltages do not draw excessive current from a sending unit at a higher volt- age. the i/o is disabled for three oscillator cycles after power up, to eliminate false alarming of remote units when the bat- tery is changed. sensitivity/low battery thresholds both the sensitivity threshold and the low battery voltage levels are set internally by a common voltage divider (please see figure 1) connected between v dd and v ss . these volt- ages can be altered by external resistors connected from pins 3 or 13 to either v dd or v ss . there will be a slight inter- action here due to the common voltage divider network. the sensitivity threshold can also be set by adjusting the smoke chamber ionization source. test mode since the internal op amps and comparators are power strobed, adjustments for sensitivity or low battery level could be difficult and/or timeconsuming. by forcing pin 12 to v ss , the power strobing is bypassed and the output, pin 1, constantly shows smoke/no smoke. pin 1 = v dd for smoke. in this mode and during the 10 ms power strobe, chip current rises to approximately 50 m a. led pulse the 9volt battery level is checked every 40 seconds dur- ing the led pulse. the battery is loaded via a 10 ma pulse for 10 ms. if the led is not used, it should be replaced with an equivalent resistor such that the battery loading remains at 10 ma. hysteresis when smoke is detected, the resistor/divider network that sets sensitivity is altered to increase sensitivity. this yields approximately 100 mv of hysteresis and reduces false triggering. figure 5. typical application as ionization smoke detector mc14468 116 2 3 4 5 6 7 8 15 14 13 12 11 10 9 330 w 8.2 m w + 9 v 0.1 m f 1.5 m w * 0.001 m f 220 k w * 0.1 m f 1 m 1 m test *note: component values may change depending on type of piezoelectric horn used. to other units f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
414 motorola sensor device data www.motorola.com/semiconductors figure 6. timing diagram hysteresis (internal) (pin 13 ) (pin 14) detect out (pin 1) low battery (internal) sample (internal) smoke horn (pin 10 and 11) led (pin 5) oscillator (pin 12) standby smoke/no low battery smoke/low battery no smoke/ no low battery no smoke/low battery 40 ms 10 ms 1.67 s 24 clock cycles (0.96 s) 24 clock cycles (40s) 24 clock cycles 6 clock suppressed chirp battery test (note 3) (note 3) (note 1) cycles (10.0 s) strobe out (pin 14) i/o (pin 2) output (local) i/o (pin 2) input (remote) led note: horn modulation not selfcompleting low = disable high = enable (suppressed led for remote only) notes: 1. horn modulation is selfcompleting. when going from smoke to no smoke, the alarm condition will terminate only when horn is o ff. 2. comparators are strobed on once per clock cycle (1.67 s for no smoke, 40 ms for smoke). 3. low battery comparator information is latched only during led pulse. 4. 100 mv pp swing. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
415 motorola sensor device data www.motorola.com/semiconductors cmos
the mc14578 is an analog building block consisting of a veryhigh input impedance comparator. the voltage follower allows monitoring the noninverting input of the comparator without loading. four enhancementmode mosfets are also included on chip. these fets can be externally configured as opendrain or totempole outputs. the drains have onchip staticprotecting diodes. therefore, the output voltage must be main- tained between v ss and v dd . the chip requires one external component. a 3.9 m w 10% resistor must be connected from the r bias pin to v dd . this circuit is designed to operate in smoke detector systems that comply with ul217 and ul268 specifications. ? applications: pulse shapers linepowered smoke detectors threshold detectors liquid/moisture sensors lowbattery detectors co detector and micro interface ? operating voltage range: 3.5 to 14 v ? operating temperature range: 30 to 70 c ? input current (in + pin): 1 pa @ 25 c (dip only) ? quiescent current: 10 m a @ 25 c ? electrostatic discharge (esd) protection circuitry on all pins semiconductor technical data p suffix plastic dip case 64808 pin assignment 16 15 14 13 12 11 10 9 1 2 3 4 5 6 7 8 comp out in a in b v dd out b in c out c1 nc in + nc buff out ine r bias v ss out c2 ordering information mc14578p plastic dip 1 16 out a logic detail 2 + comp bias ckt + buff comp out 13 buff out 15 in+ 12 in 11 r bias in a in b 3 4 5 6 out a out b 9 8 out c2 out c1 7 in c pin 1 = v dd pin 10 = v ss pins 14, 16 = no connection rev 1 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
416 motorola sensor device data www.motorola.com/semiconductors maximum ratings* (voltages referenced to v ss ) symbol parameter value unit v dd dc supply voltage 0.5 to +14 v v in dc input voltage 0.5 to v dd +0.5 v v out dc output voltage 0.5 to v dd +0.5 v i in dc input current, except in + 10 ma i in dc input current, in + 1.0 ma i out dc output current, per pin 25 ma i dd dc supply current, v dd and v ss pins 50 ma p d power dissipation, per package 500 mw t stg storage temperature 65 to +150 c t l lead temperature (10second soldering) 260 c *maximum ratings are those values beyond which damage to the device may occur. this device contains protection circuitry to guard against damage due to high static voltages or electric fields. however, prec autions must be taken to avoid applications of any voltage higher than maximum rated voltages to this highimpedance circuit. for proper ope ration, v in and v out should be constrained to the range v ss (v in or v out ) v dd . unused inputs must always be tied to an appropriate logic voltage level (e.g., either v ss or v dd ). unused outputs must be left open. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
417 motorola sensor device data www.motorola.com/semiconductors electrical characteristics (voltages referenced to v ss , r bias = 3.9 m w to v dd , t a = 30 to 70 c unless otherwise indicated) symbol parameter test condition v dd v guaranteed limit unit v dd power supply voltage range e 3.5 to 14.0 v v il maximum lowlevel input voltage, mosfets wired as inverters; i.e., in a tied to in b, out a to out b, out c1 to out c2. v out = 9.0 v, |i out | 1 m a 10.0 2.0 v v ih minimum highlevel input voltage, mosfets wired as inverters; i.e., in a tied to in b, out a to out b, out c1 to out c2. v out = 1.0 v, |i out | 1 m a 10.0 8.0 v v io comparator input offset voltage t a = 25 c, over common mode range 10.0 50 mv t a = 0 to 50 c, over common mode range 3.5 to 14.0 75 v cm comparator common mode voltage range 3.5 to 14.0 0.7 to v dd 1.5 v v ol maximum lowlevel comparator output voltage in +: v in = v ss , in : v in = v dd , i out = 30 m a 10.0 0.5 v v oh minimum highlevel comparator output voltage in +: v in = v dd , in : v in = v ss , i out = 30 m a 10.0 9.5 v v oo buffer amp output offset voltage r load = 10 m w to v dd or v ss , over common mode range e 100 mv v ol maximum lowlevel output voltage, mosfets wired as inverters ; i e in a tied to in b out out c1, out c2: i out = 1.1 ma 10.0 0.5 v wired as inverters i . e ., in a tied to in b , out a to out b, out c1 to out c2. out a, out b: i out = 270 m a 10.0 0.5 v v oh minimum highlevel output voltage, mosfets wired as inverters ; i e in a tied to in b out out c1, out c2: i out = 1.1 ma 10.0 9.5 v wired as inverters i . e ., in a tied to in b , out a to out b, out c1 to out c2. out a, out b: i out = 270 m a 10.0 9.5 v i in maximum input leakage in + (dip only) current t a = 25 c, 40% r.h., v in = v ss or v dd 10.0 1.0 pa in + (dip only) t a = 50 c, v in = v ss or v dd 10.0 6.0 in + (sog), in a, in b, in c, in v in = v ss or v dd 10.0 40 na i oz maximum offstate mosfet leakage current in a, in c: v in = v dd , out a, out c2: v out = v ss or v dd 10.0 100 na in b, in c: v in = v ss , out b, out c1: v out = v ss or v dd 10.0 100 i dd maximum quiescent current t a = 25 c in a, in b, in c: v in = v ss or v dd , |v in + v in | = 100 mv, i out = 0 m a 10.0 10 m a c in maximum input capacitance in + other inputs f = 1 khz e e 5.0 15 pf f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
418 motorola sensor device data www.motorola.com/semiconductors 16 15 14 13 12 11 10 9 1 2 3 4 5 6 7 8 nc in + nc buff out in r bias v ss out c2 out a out b in c out c1 in b in a v dd comp out r2 r1 mc14578 r4 3.9 m note: in + and in have very high input impedance. interconnect to these pins should be as short as possible. figure 1. lowbattery detector v+ d1 r3 v+ v+ v+ r5 6.8 k d2 lowbattery indicator output high = battery low low = battery ok applications information example values near the switchpoint, the comparator output in the circuit of figure 1 may chatter or oscillate. this oscillation appears on the signal labelled output. in some cases, the oscilla- tion in the transition region will not cause problems. for example, an mpu reading output could sample the signal two or three times to ensure a solid level is attained. but, in a low battery detector, this probably is not necessary. to eliminate comparator chatter, hysteresis can be added as shown in figure 2. the circuit of figure 2 requires slightly more operating current than the figure 1 arrangement. r1 r2 r3 nominal trip point 470 k w 1.3 m w 20 k w 4.08 v 820 k w 1.2 m w 39 k w 5.05 v 1.2 m w 1.2 m w 62 k w 6.00 v figure 2. adding hysteresis + r7 2 15 12 r6 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
419 motorola sensor device data www.motorola.com/semiconductors lowpower cmos
with horn driver the mc14600 alarm ic is designed to simplify the process of interfacing an alarm level voltage condition to a piezoelectric horn and/or led. with an extremely low average current requirement and an integrated low battery detect feature, the part is ideally suited to battery operated applications. the mc14600 is easily configured with a minimum number of external components to serve a wide range of applications and circuit configurations. typical applications include intrusion alarms, moisture or water ingress alarms, and personal safety devices. ? high impedance, fet input comparator ? comparator outputs for low battery and alarm detect ? alarm detect threshold easily established with 2 resistor ? integrated oscillator and piezoelectric horn driver ? low battery trip point set internally (altered externally) ? horn achirp'' during low battery condition ? pulsed led drive output ? reverse battery protection ? input protection diodes on the detect input ? average supply current: 9 m a maximum ratings* (voltages referenced to v ss ) rating symbol value unit dc supply voltage v dd 0.5 to + 15 v input voltage, all inputs except pin 8 v in 0.25 to v dd + 0.25 v dc current drain per input pin, except pin 15 = 1 ma i 10 ma dc current drain per output pin i 30 ma operating temperature range t a 10 to + 60 c c storage temperature range t stg 55 to + 125 c reverse battery time t rb 5.0 s * maximum ratings are those values beyond which damage to the device may occur. this device contains circuitry to protect the inputs against damage due to high static voltages or electric fields; however, it is advised that normal precautions be taken to avoid application of any voltage higher than maximum rated voltages to this high impedance circuit. for proper operation it is recommended that v in and v out be constrained to the range v ss (v in or v out ) v dd .
semiconductor technical data
p suffix plastic dip case 64808 pin assignment (16 pin dip) 16 15 14 13 12 11 10 9 1 2 3 4 5 6 7 8 detect comp. out n/c low v set low v comp. out led v dd timing resistor horn feedback guard alarm detect input n/c alarm threshold osc capacitor horn out 2 horn out 1 v ss ordering information 1 16 mc14600p plastic dip mc14600dw soic mc14600dwr2 soic tape & reel dw suffix soic package case 751g03 1 16 rev 3 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
420 motorola sensor device data www.motorola.com/semiconductors recommended operating conditions (voltages referenced to v ss ) parameter symbol value unit supply voltage v dd 9.0 v led (pin 5) load e 10 ma electrical characteristics (voltages referenced to v ss , ta = 25 c) characteristic pin # symbol v dd v dc min typ max unit operating voltage 6 v dd e 6.0 e 12 v output voltage piezoelectric horn drivers (i oh = +16 ma) comparators (i oh = +30 m a) piezoelectric horn drivers (i ol = 16 ma) comparators (i ol = 30 m a) (i ol = 200 m a) 10,11 4 10,11 4 1 v oh v ol 7.4 9.0 7.4 9.0 e 6.5 8.5 e e e e 8.8 e 0.1 e e e 0.9 0.5 0.5 v v output voltage e led driver, i ol = 10 ma 5 v ol 7.2 e e 2.0 v output impedance, active guard 16 hiz 9.0 e e 1000 k w standby current (r bias = 8.2 m w ) e i dd 9.0 12.0 e e 5.0 e 9.0 12.0 m a input leakage current 1 8 13 e i in e 9.0 9.0 9.0 e e e e e e 30 0.1 30 na m a na detect comp. out v = 3 v v = 9 v 1 e e e e 2.50 e e e e 8.00 ma ma low battery threshold voltage (pin 3 open) 6 v low 9.0 7.2 e 7.8 v offset voltage (measured at v in = vdd/2) active guard detect comparator 16 13,15 v os 9.0 9.0 e e e e 100 50 mv input voltage range 8 v in e vss 10 e vdd + 10 v input capacitance (to v ss @ 1 khz) 15 c in e e 5.0 e pf common mode voltage range 13,15 v cm e 1.5 e vdd 2 v breakdown voltage human body models per milstd883 method 3015 all pins except 15 15 e e e e 500 400 e e e e v # data labelled atyp'' is not to be used for design purposes but is intended as an indication of the ic's potential performance . f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
421 motorola sensor device data www.motorola.com/semiconductors timing parameters (cosc = 0.1 m f, r bias = 8.2 m w , v dd = 9.0 v, t a = 25 c, see figure 2) characteristics pin # symbol min max units oscillator period (1 clock cycle = 1 oscillator period) no alarm alarm 12 t ci e 1.25 30 2.25 52 s ms oscillator pulse width (no alarm and alarm condition) 3,4,5,13 t r 7.0 13 ms led output period no alarm alarm 5 t led e 30 .71 52 1.25 s ms alarm horn output hi time low time 10,11 t on t off 120 60 208 104 ms ms low battery horn output hi time between pulses 10,11 t on t off 7.0 30 13 52 ms s figure 1. block diagram 11 10 8 horn feedback horn out 2 horn out 1 alarm logic osc and timing 5 led v dd = pin 6 v ss = pin 9 7 v dd + low battery comparator v dd low v comp. out 4 v dd 3 low v set 1 detect comparator out + 13 detect comparator alarm threshold 15 alarm detect input + v dd hiz 16 guard amp 12 cosc rbias f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
422 motorola sensor device data www.motorola.com/semiconductors device operation timing the internal oscillator of the mc14600 operates with a period of 1.65 seconds during noalarm conditions. each 1.65 seconds, internal power is applied to the entire ic and a check is made for an alarm input level except during led pulse, low battery alarm chirp, or horn modulation (in alarm). every 24 clock cycles a check is made for low battery by comparing v dd to an internal zener voltage. since very small currents are used in the oscillator, the oscillator capaci- tor should be of a low leakage type. detect circuitry if an alarm condition is detected, the oscillator period becomes 41.67 ms and the piezoelectric horn oscillator cir- cuit is enabled. the horn output is modulated 167 ms on, 83 ms off. during the off time, alarm detect input (pin 15) is again checked and will inhibit further horn output if no alarm condition is sensed. during alarm conditions the low battery chirp is inhibited, and the led pulses at a 1.0 hz rate. an active guard is provided on a pin adjacent to the detect input (pin 16). the voltage at this pin will be within 100 mv of the input signal. pin 16 will allow monitoring of the input sig- nal at pin 15 through a buffer. the active guard op amp is not power strobed and thus gives constant protection from sur- face leakage currents. pin 15 (the detect input) has internal diode protection against static damage. low battery threshold the low battery voltage level is set internally by a voltage divider connected between v dd and v ss . this voltage can be altered by external resistors connected from pin 3 to either v dd or v ss . a resistor to v dd will decrease the thresh- old while a resistor to gnd will increase it. alarm threshold (sensitivity) the alarm condition voltage level is set externally through pin 13. a voltage divider can be used to set the alarm trip point. pin 13 is connected internally to the negative input of the detect comparator. led pulse the 9volt battery level is checked every 40 seconds dur- ing the led pulse. the battery is loaded via a 10 ma pulse for 10 ms. if the led is not used, it should be replaced with an equivalent resistor so that the battery loading remains at 10 ma. figure 2. typical application components mc14600 116 2 3 4 5 6 7 8 15 14 13 12 11 10 9 330 w r bias 0.1 m f 1.5 m w * 0.001 m f 220 k w * c osc *note: component values may change depending on type of piezoelectric horn used. detect input r1 r2 v dd rp v dd v dd f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
423 motorola sensor device data www.motorola.com/semiconductors figure 3. mc14600 timing diagram osc pin 12 alarm n y low batt comp (pin 4) detect out (pin 1) led off on 234567 9 8 no alarm, low battery 1 no alarm no low bat low battery chirp osc pin 12 alarm n y no alarm 23 24 1 6 12 18 24 alarm latch alarm condition horn on off led off on (note 1) 24 clocks 24 clocks horn (pins 10 and 11) low batt comp detect out (pin 1) notes: 1. horn modulation is selfcompleting. when going from alarm to no alarm, the alarm condition will terminate only when horn is o ff. 2. comparators are strobed once per cycle. 3. low battery comparator information is latched only during led pulse. 4. current source required into pin 1. 5. alarm condition can initiate on any clock pulse except 1 and 7. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
424 motorola sensor device data www.motorola.com/semiconductors

the cmos mc145010 is an advanced smoke detector component containing sophisticated verylowpower analog and digital circuitry. the ic is used with an infrared photoelectric chamber. detection is accomplished by sensing scattered light from minute smoke particles or other aerosols. when detection occurs, a pulsating alarm is sounded via onchip pushpull drivers and an external piezoelectric transducer. the variablegain photo amplifier allows direct interface to ir detectors (photodiodes). two external capacitors, c1 and c2, c1 being the larger, determine the gain settings. low gain is selected by the ic during most of the standby state. medium gain is selected during a localsmoke condition. high gain is used during pushbutton test. during standby, the special monitor circuit which periodically checks for degraded chamber sensitivity uses high gain, also. the i/o pin, in combination with v ss , can be used to interconnect up to 40 units for common signaling. an onchip current sink provides noise immunity when the i/o is an input. a localsmoke condition activates the shortcircuit protected i/o driver, thereby signaling remote smoke to the interconnected units. additionally, the i/o pin can be used to activate escape lights, enable auxiliary or remote alarms, and/or initiate autodialers. while in standby, the lowsupply detection circuitry conducts periodic checks using a pulsed load current from the led pin. the trip point is set using two external resistors. the supply for the mc145010 can be a 9 v battery. a visible led flash accompanying a pulsating audible alarm indicates a localsmoke condition. a pulsating audible alarm with no led flash indicates a remotesmoke condition. a beep or chirp occurring virtually simultaneously with an led flash indicates a lowsupply condition. a beep occurring halfway between led flashes indicates degraded chamber sensitivity. a lows upply condition does not affect the smoke detection capability if v dd 6 v. therefore, the lowsupply condition and degraded chamber sensitivity can be further distinguished by performing a pushbutton (chamber) test. ? circuit is designed to operate in smoke detector systems that comply with ul217 and ul268 specifications ? operating voltage range: 6 to 12 v ? operating temperature range: 10 to 60 c ? average supply current: 12 m a ? poweron reset places ic in standby mode (nonalarm state) ? electrostatic discharge (esd) and latch up protection circuitry on all pins ? chip complexity: 2000 fets, 12 npns, 16 resistors, and 10 capacitors ? ideal for battery powered applications. semiconductor technical data p suffix plastic dip case 64808 pin assignment 16 15 14 13 12 11 10 9 1 2 3 4 5 6 7 8 c1 c2 detect strobe v dd ired i/o brass test lowsupply trip v ss r1 osc led feedback silver ordering information mc145010p plastic dip mc145010dw soic package 1 16 dw suffix soic package case 751g03 1 16 rev 4 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
425 motorola sensor device data www.motorola.com/semiconductors block diagram + + detect osc r1 test strobe lowsupply trip 3 12 13 16 4 15 2 1 c1 c2 osc amp comp comp alarm logic horn modulator and driver v dd 5 v ref timing logic v dd 3.5 v ref zero gain low supply smoke gate on/off gate on/off 8 9 10 6 11 7 pin 5 = v dd pin 14 = v ss led ired feedback silver brass i/o maximum ratings* (voltages referenced to v ss ) symbol parameter value unit v dd dc supply voltage 0.5 to +12 v v in dc input voltage c1, c2, detect osc, lowsupply trip i/o feedback test 0.25 to v dd +0.25 0.25 to v dd +0.25 0.25 to v dd +10 15 to +25 1.0 to v dd +0.25 v i in dc input current, per pin 10 ma i out dc output current, per pin 25 ma i dd dc supply current, v dd and v ss pins +25 / 150 ma p d power dissipation in still air, 5 seconds continuous 1200** 350*** mw t stg storage temperature 55 to +125 c t l lead temperature, 1 mm from case for 10 seconds 260 c * maximum ratings are those values beyond which damage to the device may occur. functional operation should be restricted to the limits in the electrical characteristics tables. ** derating: 12 mw/ c from 25 to 60 c. *** derating: 3.5 mw/ c from 25 to 60 c. this device contains protection circuitry to guard against damage due to high static voltages or electric fields. however, prec autions must be taken to avoid applications of any voltage higher than maximum rated voltages to this highimpedance circuit. for proper ope ration, v in and v out should be constrained to the range v ss (v in or v out ) v dd except for the i/o, which can exceed v dd , and the test input, which can go below v ss . unused inputs must always be tied to an appropriate logic voltage level (e.g., either v ss or v dd ). unused outputs and/or an unused i/o must be left open. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
426 motorola sensor device data www.motorola.com/semiconductors electrical characteristics (t a = 10 to 60 c unless otherwise indicated, voltages referenced to v ss ) symbol parameter test condition v dd v min max unit v dd power supply voltage range e 6.0 12 v v th supply threshold voltage, lowsupply alarm lowsupply trip: vin = vdd/3 e 6.5 7.8 v i dd average operating supply current (per package) standby configured per figure 5 12.0 e 12 m a i dd peak supply current (per package) during strobe on, ired off configured per figure 5 12.0 e 2.0 ma during strobe on, ired on configured per figure 5 12.0 e 3.0 v il lowlevel input voltage i/o feedback test 9.0 9.0 9.0 e e e 1.5 2.7 7.0 v v ih highlevel input voltage i/o feedback test 9.0 9.0 9.0 3.2 6.3 8.5 e e e v i in input current osc, detect lowsupply trip feedback v in = v ss or v dd v in = v ss or v dd v in = v ss or v dd 12.0 12.0 12.0 e e e 100 100 100 na i il lowlevel input current test v in = v ss 12.0 e 1 m a i ih pulldown current test i/o v in = v dd no local smoke, v in = v dd no local smoke, v in = 17 v 9.0 9.0 12.0 0.5 25 e 10 100 140 m a v ol lowlevel output voltage led silver, brass i out = 10 ma i out = 16 ma 6.5 6.5 e e 0.6 1.0 v v oh highlevel output voltage silver, brass i out = 16 ma 6.5 5.5 e v v out output voltage strobe (for line regulation, see pin descriptions) inactive, i out = 1 m a active, i out = 100 m a to 500 m a (load regulation) e 9.0 v dd 0.1 v dd 4.4 e v dd 5.6 v ired inactive, i out = 1 m a active, i out = 6 ma (load regulation) e 9.0 e 2.25* 0.1 3.75* i oh highlevel output current i/o local smoke, v out = 4.5 v 6.5 4 e ma local smoke, v out = v ss (short circuit current) 12.0 e 16 i oz offstate output leakage current led v out = v ss or v dd 12.0 e 1 m a v ic common mode c1, c2, detect voltage range local smoke, pushbutton test, or chamber sensitivity test e v dd 4 v dd 2 v v ref smoke comparator internal reference voltage local smoke, pushbutton test, or chamber sensitivity test e v dd 3.08 v dd 3.92 v *t a = 25 c only. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
427 motorola sensor device data www.motorola.com/semiconductors ac electrical characteristics (reference timing diagram figures 3 and 4) (t a = 25 c, v dd = 9.0 v, component values from figure 5: r1 = 100.0 k w , c3 = 1500.0 pf, r2 = 10.0 m w ) no. symbol parameter test condition clocks min max unit 1 1/f osc oscillator period* freerunning sawtooth measured at pin 12 1 9.5 11.5 ms 2 t led led pulse period no local smoke, and no remote smoke 4096 38.9 47.1 s 3 remote smoke, but no local smoke e none 4 local smoke or pushbutton test 64 0.60 0.74 5 t w(led) , t w(stb) led pulse width and strobe pulse width 1 9.5 11.5 ms 6 t ired ired pulse period smoke test 1024 9.67 11.83 s 7 chamber sensitivity test, without local smoke 4096 38.9 47.1 8 pushbutton test 32 0.302 0.370 9 t w(ired) ired pulse width t f * 94 116 m s 10 t r ired rise time e e 30 m s t f ired fall time e e 200 11 t mod silver and brass modulation period local or remote smoke e 297 363 ms 11,12 t on /t mod silver and brass duty cycle local or remote smoke e 73 77 % 13 t ch silver and brass chirp pulse period low supply or degraded chamber sensitivity 4096 38.9 47.1 s 14 t w(ch) silver and brass chirp pulse width low supply or degraded chamber sensitivity 1 9.5 11.5 ms 15 t rr rising edge on i/o to smoke alarm response time remote smoke, no local smoke e e 800 ms 16 t stb strobe out pulse period smoke test 1024 9.67 11.83 s 17 chamber sensitivity test, without local smoke 4096 38.9 47.1 18 low supply test, without local smoke 4096 38.9 47.1 19 pushbutton test e 0.302 0.370 * oscillator period t (= t r + t f ) is determined by the external components r1, r2, and c3 where t r = (0.6931) r 2 * c 3 and t f = (0.6931) r 1 * c 3 . the other timing characteristics are some multiple of the oscillator timing as shown in the table. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
428 motorola sensor device data www.motorola.com/semiconductors figure 1. ac characteristics versus supply pulse width of ired period or pulse width of other parameters ac parameter (normalized to 9.0 v value) v dd , power supply voltage (v) 1.02 0.98 0.96 1.00 1.04 6.0 7.0 8.0 9.0 10.0 11.0 12.0 t a = 25 c figure 2a. ac characteristics versus temperature note: includes external component variations. see figure 2b. pulse width of ired period or pulse width of other parameters ac parameter (normalized to 25 c value) t a , ambient temperature ( c) 10 0 10 20 30 40 50 60 1.02 1.01 0.99 0.98 1.00 v dd = 9.0 v figure 2. figure 2b. rc component variation over temperature note: these components were used to generate figure 2a. 10 m w carbon composition 100 k w metal film 1500 pf dipped mica component value (normalized to 25 c value) t a , ambient temperature ( c) 10 0 10 20 30 40 50 60 1.03 1.02 1.01 1.00 0.99 0.98 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
429 motorola sensor device data www.motorola.com/semiconductors figure 3. standby timing diagram low supply test (internal) smoke test (internal) chamber test (internal) 7 osc (pin 12) 1 led (pin 11) silver, brass (internal) enable 2 13 13 poweron reset no low supply chirps ired (pin 6) strobe (pin 4) 6 6 16 17 5 14 18 notes: numbers refer to the ac electrical characteristics table. illustration is not to scale. chamber sensitivity ok indicate low supply chirps indicate degraded chamber sensitivity 9 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
430 motorola sensor device data www.motorola.com/semiconductors figure 4. smoke timing diagram low supply test (internal) ired (pin 6) chamber test (internal) strobe (pin 4) 6 i/o (pin 7) silver, brass (not performed) (not performed) 11 10 9 ired 10% 90% 5 8 19 led (pin 11) 5 4 3 (no pulses) (as input) (as output) (as output) enable (internal) 15 12 11 no smoke pushbutton no smoke local smoke (remote smoke = don't care) remote smoke (no local smoke) 4 notes: numbers refer to the ac electrical characteristics table. illustration is not to scale. test f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
431 motorola sensor device data www.motorola.com/semiconductors 16 15 14 13 12 11 10 9 1 2 3 4 5 6 7 8 test lowsupply trip v ss r1 osc led feedback silver v dd ired i/o brass strobe detect c1 c2 horn x1 to other mc145010(s), escape light(s), auxiliary alarm(s), remote alarm(s), and/or autodialer ir current r13* 4.7 to 22 q1 2.2 m r5 d4 visible led r7 47 k r6 100 k sw1 + + mc145010 reverse polarity protection circuit pushbutton test r2 10 m 0.01 m f c6 c3 1500 pf r1 100 k r3 470 r4 100 k 9 v b1 d1 1 to 22 m f c4** c1 0.047 m f c2* 4700 pf r14 560 w r11 250 k d2 ir detector r8 8.2 k r9 2 5 k r10 4.7 k d3 ir emitter r12 1 k c5 100 m f values for r4, r5, and c6 may differ depending on type of piezoelectric horn used. * c2 and r13 are used for coarse sensitivity adjustment. typical values are shown. 2r9 is for fine sensitivity adjustment (optional). if fixed resistors are used, r8 = 12 k, r10 is 5.6 k to 10 k, and r9 is elim inated. when r9 is used, noise pickup is increased due to antenna effects. shielding may be required. **c4 should be 22 m f if b1 is a carbon battery. c4 could be reduced to 1 m f when an alkaline battery is used. figure 5. typical batterypowered application pin descriptions c1 (pin 1) a capacitor connected to this pin as shown in figure 5 determines the gain of the onchip photo amplifier during pushbutton test and chamber sensitivity test (high gain). the capacitor value is chosen such that the alarm is tripped from background reflections in the chamber during pushbutton test. a v 1 + (c1/10) where c1 is in pf. caution: the value of the closedloop gain should not exceed 10,000. c2 (pin 2) a capacitor connected to this pin as shown in figure 5 determines the gain of the onchip photo amplifier except during pushbutton or chamber sensitivity tests. a v 1 + (c2/10) where c2 is in pf. this gain increases about 10% during the ired pulse, after two consecutive local smoke detections. resistor r14 must be installed in series with c2. r14 [1/(12 c2 )] 680 where r14 is in ohms and c2 is in farads. detect (pin 3) this input to the highgain pulse amplifier is tied to the cathode of an external photodiode. the photodiode should have low capacitance and low dark leakage current. the diode must be shunted by a load resistor and is operated at zero bias. the detect input must be ac/dc decoupled from all other signals, v dd , and v ss . lead length and/or foil traces to this pin must be minimized, also. see figure 6. strobe (pin 4) this output provides a strobed, regulated voltage refer- enced to v dd . the temperature coefficient of this voltage is 0.2%/ c maximum from 10 to 60 c. the supplyvoltage coefficient (line regulation) is 0.2%/v maximum from 6 to 12 v. strobe is tied to external resistor string r8, r9, and r10. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
432 motorola sensor device data www.motorola.com/semiconductors v dd (pin 5) this pin is connected to the positive supply potential and may range from +6 to +12 v with respect to v ss . caution: in batterypowered applications, reverse polarity protection must be provided externally. ired (pin 6) this output provides pulsed base current for external npn transistor q1 used as the infrared emitter driver. q1 must have b 100. at 10 ma, the temperature coefficient of the output voltage is typically + 0.5%/ c from 10 to 60 c. the supplyvoltage coefficient (line regulation) is 0.2%/v maxi- mum from 6 to 12 v. the ired pulse width (activehigh) is determined by external components r1 and c3. with a 100 k w /1500 pf combination, the nominal width is 105 m s. to minimize noise impact, ired is not active when the vis- ible led and horn outputs are active. ired is active near the end of strobe pulses for smoke tests, chamber sensitivity test, and pushbutton test. i/o (pin 7) this pin can be used to connect up to 40 units together in a wiredor configuration for common signaling. v ss is used as the return. an onchip current sink minimizes noise pick up during nonsmoke conditions and eliminates the need for an external pulldown resistor to complete the wiredor. remote units at lower supply voltages do not draw excessive current from a sending unit at a higher supply voltage. i/o can also be used to activate escape lights, auxiliary alarms, remote alarms, and/or autodialers. as an input, this pin feeds a positiveedgetriggered flip flop whose output is sampled nominally every 625 ms during standby (using the recommended component values). a localsmoke condition or the pushbuttontest mode forces this currentlimited output to source current. all input signals are ignored when i/o is sourcing current. i/o is disabled by the onchip poweron reset to elimi- nate nuisance signaling during battery changes or system powerup. if unused, i/o must be left unconnected. brass (pin 8) this half of the pushpull driver output is connected to the metal support electrode of a piezoelectric audio transducer and to the hornstarting resistor. a continuous modulated tone from the transducer is a smoke alarm indicating either local or remote smoke. a short beep or chirp is a trouble alarm indicating a low supply or degraded chamber sensitivity. silver (pin 9) this half of the pushpull driver output is connected to the ceramic electrode of a piezoelectric transducer and to the hornstarting capacitor. feedback (pin 10) this input is connected to both the feedback electrode of a selfresonating piezoelectric transducer and the hornstart- ing resistor and capacitor through currentlimiting resistor r4. if unused, this pin must be tied to v ss or v dd . led (pin 11) this activelow opendrain output directly drives an exter- nal visible led at the pulse rates indicated below. the pulse width is equal to the osc period. the load for the lowsupply test is applied by this output. this lowsupply test is noncoincident with the smoke tests, chamber sensitivity test, pushbutton test, or any alarm signals. the led also provides a visual indication of the detector status as follows, assuming the component values shown in figure 5: standby (includes lowsupply and chamber sensitivity tests) e pulses every 43 seconds (nominal) local smoke e pulses every 0.67 seconds (nominal) remote smoke e no pulses pushbutton test e pulses every 0.67 seconds (nominal) osc (pin 12) this pin is used in conjunction with external resistor r2 (10 m w ) to v dd and external capacitor c3 (1500 pf) to v dd to form an oscillator with a nominal period of 10.5 ms. r1 (pin 13) this pin is used in conjunction with resistor r1 (100 k w ) to pin 12 and c3 (1500 pf, see pin 12 description) to determine the ired pulse width. with this rc combination, the nominal pulse width is 105 m s. v ss (pin 14) this pin is the negative supply potential and the return for the i/o pin. pin 14 is usually tied to ground. lowsupply trip (pin 15) this pin is connected to an external voltage which deter- mines the lowsupply alarm threshold. the trip voltage is obtained through a resistor divider connected between the v dd and led pins. the lowsupply alarm threshold voltage (in volts) (5r7/r6) + 5 where r6 and r7 are in the same units. test (pin 16) this input has an onchip pulldown device and is used to manually invoke a test mode. the pushbutton test mode is initiated by a high level at pin 16 (usually depression of a s.p.s.t. normallyopen pushbut- ton switch to v dd ). after one oscillator cycle, ired pulses approximately every 336 ms, regardless of the presence of smoke. additionally, the amplifier gain is increased by auto- matic selection of c1. therefore, the background reflections in the smoke chamber may be interpreted as smoke, gener- ating a simulatedsmoke condition. after the second ired pulse, a successful test activates the horndriver and i/o cir- cuits. the active i/o allows remote signaling for system test- ing. when the pushbutton test switch is released, the test input returns to v ss due to the onchip pulldown device. after one oscillator cycle, the amplifier gain returns to nor- mal, thereby removing the simulatedsmoke condition. after two additional ired pulses, less than a second, the ic exits the alarm mode and returns to standby timing. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
433 motorola sensor device data www.motorola.com/semiconductors calibration to facilitate checking the sensitivity and calibrating smoke detectors, the mc145010 can be placed in a calibration mode. in this mode, certain device pins are controlled/recon- figured as shown in table 1. to place the part in the calibra- tion mode, pin 16 (test) must be pulled below the v ss pin with 100 m a continuously drawn out of the pin for at least one cycle on the osc pin. to exit this mode, the test pin is floated for at least one osc cycle. in the calibration mode, the ired pulse happens at every clock cycle and strobe is always on (active low). also, low battery and supervisory tests are disabled in this mode. table 1. configuration of pins in the calibration mode description pin comment i/o 7 disabled as an output. forcing this pin high places the photo amp output on pin 1 or 2, as determined by lowsupply trip. the amp's output appears as pulses and is referenced to v dd . lowsupply trip 15 if the i/o pin is high, pin 15 controls which gain capacitor is used. low: normal gain, amp output on pin 1. high: supervisory gain, amp output on pin 2. feedback 10 driving this input high enables hysteresis (10% gain increase) in the photo amp; pin 15 must be low. osc 12 driving this input high brings the internal clock high. driving the input low brings the internal clock low. if desired, the rc network for the oscillator may be left intact; this allows the oscillator to run similar to the normal mode of operation. silver 9 this pin becomes the smoke comparator output. when the osc pin is toggling, positive pulses indicate that smoke has been detected. a static low level indicates no smoke. brass 8 this pin becomes the smoke integrator output. that is, 2 consecutive smoke detections are required for aono (static high level) and 2 consecutive nodetections for aoffo (static low level). notes: illustration is bottom view of layout using a dip. top view for soic layout is mirror image. optional potentiometer r9 is not included. drawing is not to scale. leads on d2, r11, r8, and r10 and their associated traces must be kept as short as possible. this practice minimizes noise pick up. pin 3 must be decoupled from all other traces. figure 6. recommended pcb layout do not run any additional traces in this region pin 8 pin 16 pin 9 pin 1 c1 r14 r11 d2 r8 mounted in chamber c2 r10 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
434 motorola sensor device data www.motorola.com/semiconductors

for linepowered applications the cmos mc145011 is an advanced smoke detector component containing sophisticated verylowpower analog and digital circuitry. the ic is used with an infrared photoelectric chamber. detection is accomplished by sensing scattered light from minute smoke particles or other aerosols. when detection occurs, a pulsating alarm is sounded via onchip pushpull drivers and an external piezoelectric transducer. the variablegain photo amplifier allows direct interface to ir detectors (photodiodes). two external capacitors c1 and c2, c1 being the larger, determine the gain settings. low gain is selected by the ic during most of the standby state. medium gain is selected during a localsmoke condition. high gain is used during pushbutton test. during standby, the special monitor circuit which periodically checks for degraded chamber sensitivity uses high gain, also. the i/o pin, in combination with v ss , can be used to interconnect up to 40 units for common signaling. an onchip current sink provides noise immunity when the i/o is an input. a localsmoke condition activates the shortcircuitprotected i/o driver, thereby signaling remote smoke to the interconnected units. additionally, the i/o pin can be used to activate escape lights, enable auxiliary or remote alarms, and/or initiate autodialers. while in standby, the lowsupply detection circuitry conducts periodic checks using a load current from the led pin. the trip point is set using two external resistors. the supply for the mc145011 must be a dc power source capable of supplying 35 ma continuously and 45 ma peak. when the mc145011 is in standby, an external led is continuously illuminated to indicate that the device is receiving power. an extinguished led accompanied by a pulsating audible alarm indicates a localsmoke condition. a pulsating audible alarm with the led illuminated indicates a remotesmoke condition. a beep or chirp indicates a lowsupply condition or degraded chamber sensitivity. a lowsupply condition does not affect the smoke detection capability if v dd 6 v. therefore, the lowsupply condition and degraded chamber sensitivity can be distinguished by performing a pushbutton (chamber) test. this circuit is designed to operate in smoke detector systems that comply with ul217 and ul268 specifications. ? operating voltage range: 6 to 12 v ? operating temperature range: 10 to 60 c ? average standby supply current (visible led illuminated): 20 ma ? poweron reset places ic in standby mode (nonalarm state) ? electrostatic discharge (esd) and latch up protection circuitry on all pins ? chip complexity: 2000 fets, 12 npns, 16 resistors, and 10 capacitors semiconductor technical data p suffix plastic dip case 64808 pin assignment 16 15 14 13 12 11 10 9 1 2 3 4 5 6 7 8 c1 c2 detect strobe v dd ired i/o brass test lowsupply trip v ss r1 osc led feedback silver ordering information mc145011p plastic dip mc145011dw soic package 1 16 dw suffix plastic soic case 751g03 1 16 rev 3 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
435 motorola sensor device data www.motorola.com/semiconductors + + detect osc r1 test strobe lowsupply trip 3 12 13 16 4 15 2 1 c1 c2 osc amp comp comp alarm logic horn modulator and driver v dd 5 v ref timing logic v dd 3.5 v ref zero gain low supply smoke gate on/off gate on/off 8 9 10 6 11 7 pin 5 = v dd pin 14 = v ss led ired feedback silver brass i/o block diagram maximum ratings* (voltages referenced to v ss ) symbol parameter value unit v dd dc supply voltage 0.5 to +12 v v in dc input voltage c1, c2, detect osc, lowsupply trip i/o feedback test 0.25 to v dd +0.25 0.25 to v dd +0.25 0.25 to v dd +10 15 to +25 1.0 to v dd +0.25 v i in dc input current, per pin 10 ma i out dc output current, per pin 25 ma i dd dc supply current, v dd and v ss pins +25 / 150 ma p d power dissipation in still air, 5 seconds continuous 1200** 350*** mw t stg storage temperature 55 to +125 c t l lead temperature, 1 mm from case for 10 seconds 260 c * maximum ratings are those values beyond which damage to the device may occur. functional operation should be restricted to the limits in the electrical characteristics tables. ** derating: 12 mw/ c from 25 to 60 c. *** derating: 3.5 mw/ c from 25 to 60 c. this device contains protection circuitry to guard against damage due to high static voltages or electric fields. however, prec autions must be taken to avoid applications of any voltage higher than maximum rated voltages to this highimpedance circuit. for proper ope ration, v in and v out should be constrained to the range v ss (v in or v out ) v dd except for the i/o, which can exceed v dd , and the test input, which can go below v ss . unused inputs must always be tied to an appropriate logic voltage level (e.g., either v ss or v dd ). unused outputs and/or an unused i/o must be left open. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
436 motorola sensor device data www.motorola.com/semiconductors electrical characteristics (t a = 10 to 60 c unless otherwise indicated, voltages referenced to v ss ) symbol parameter test condition v dd v min max unit v dd power supply voltage range e 6.0 12 v v th supply threshold voltage, lowsupply alarm lowsupply trip: v in = v dd /3 e 6.5 7.8 v i dd average operating supply current, excluding the visible led current (per package) standby configured per figure 5 12.0 e 12 m a i dd peak supply current , excluding the visible led current (per package) during strobe on, ired off configured per figure 5 12.0 e 2.0 ma during strobe on, ired on configured per figure 5 12.0 e 3.0 v il lowlevel input voltage i/o feedback test 9.0 9.0 9.0 e e e 1.5 2.7 7.0 v v ih highlevel input voltage i/o feedback test 9.0 9.0 9.0 3.2 6.3 8.5 e e e v i in input current osc, detect lowsupply trip feedback v in = v ss or v dd v in = v ss or v dd v in = v ss or v dd 12.0 12.0 12.0 e e e 100 100 100 na i il lowlevel input current test v in = v ss 12.0 e 1 m a i ih pulldown current test i/o v in = v dd no local smoke, v in = v dd no local smoke, v in = 17 v 9.0 9.0 12.0 0.5 25 e 10 100 140 m a v ol lowlevel output voltage led silver, brass i out = 10 ma i out = 16 ma 6.5 6.5 e e 0.6 1.0 v v oh highlevel output voltage silver, brass i out = 16 ma 6.5 5.5 e v v out output voltage strobe (for line regulation, see pin descriptions) inactive, i out = 1 m a active, i out = 100 m a to 500 m a (load regulation) e 9.0 v dd 0.1 v dd 4.4 e v dd 5.6 v ired inactive, i out = 1 m a active, i out = 6 ma (load regulation) e 9.0 e 2.25* 0.1 3.75* i oh highlevel output current i/o local smoke, v out = 4.5 v 6.5 4 e ma local smoke, v out = v ss (short circuit current) 12.0 e 16 i oz offstate output leakage current led v out = v ss or v dd 12.0 e 1 m a v ic common mode c1, c2, detect voltage range local smoke, pushbutton test, or chamber sensitivity test e v dd 4 v dd 2 v v ref smoke comparator internal reference voltage local smoke, pushbutton test, or chamber sensitivity test e v dd 3.08 v dd 3.92 v *t a = 25 c only. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
437 motorola sensor device data www.motorola.com/semiconductors ac electrical characteristics (reference timing diagram figures 3 and 4) (t a = 25 c, v dd = 9.0 v, component values from figure 5: r1 = 100.0 k w , c3 = 1500.0 pf, r2 = 10.0 m w ) no. symbol parameter test condition min max unit 1 1/f osc oscillator period* freerunning sawtooth measured at pin 12 9.5 11.5 ms 2 t led led status no local smoke, and no remote smoke illuminated 3 remote smoke, but no local smoke illuminated 4 local smoke or pushbutton test extinguished 5 t w(stb) strobe pulse width 9.5 11.5 ms 6 t ired ired pulse period smoke test 9.67 11.83 s 7 chamber sensitivity test, without local smoke 38.9 47.1 8 pushbutton test 0.302 0.370 9 t w(ired) ired pulse width 94 116 m s 10 t r ired rise time e 30 m s t f ired fall time e 200 11 t mod silver and brass modulation period local or remote smoke 297 363 ms 11, 12 t on /t mod silver and brass duty cycle local or remote smoke 73 77 % 13 t ch silver and brass chirp pulse period low supply or degraded chamber sensitivity 38.9 47.1 s 14 t w(ch) silver and brass chirp pulse width low supply or degraded chamber sensitivity 9.5 11.5 ms 15 t rr rising edge on i/o to smoke alarm response time remote smoke, no local smoke e 800 ms 16 t stb strobe pulse period smoke test 9.67 11.83 s 17 chamber sensitivity test, without local smoke 38.9 47.1 18 low supply test, without local smoke 38.9 47.1 19 pushbutton test 0.302 0.370 * oscillator period t (= t r + t f ) is determined by the external components r1, r2, and c3 where t r = (0.6931) r2 c3 and t f = (0.6931) r1 c3. the other timing characteristics are some multiple of the oscillator timing as shown in the table. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
438 motorola sensor device data www.motorola.com/semiconductors figure 1. ac characteristics versus supply pulse width of ired period or pulse width of other parameters ac parameter (normalized to 9.0 v value) v dd , power supply voltage (v) 1.02 0.98 0.96 1.00 1.04 6.0 7.0 8.0 9.0 10.0 11.0 12.0 t a = 25 c figure 2a. ac characteristics versus temperature note: includes external component variations. see figure 2b. pulse width of ired period or pulse width of other parameters ac parameter (normalized to 25 c value) t a , ambient temperature ( c) 10 0 10 20 30 40 50 60 1.02 1.01 0.99 0.98 1.00 v dd = 9.0 v figure 2. figure 2b. rc component variation over temperature note: these components were used to generate figure 2a. 10 m w carbon composition 100 k w metal film 1500 pf dipped mica component value (normalized to 25 c value) t a , ambient temperature ( c) 10 0 10 20 30 40 50 60 1.03 1.02 1.01 1.00 0.99 0.98 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
439 motorola sensor device data www.motorola.com/semiconductors low supply test (internal) smoke test (internal) chamber test (internal) 7 osc (pin 12) 1 led (pin 11) silver, brass (internal) enable 2 13 13 poweron reset no low supply e chamber sensitivity ok chirps indicate low supply chirps indicate degraded chamber sensitivity ired (pin 6) strobe (pin 4) 6 6 16 17 14 18 notes: numbers refer to the ac electrical characteristics table. illustration is not to scale. (continuously illuminated) 9 figure 3. standby timing diagram f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
440 motorola sensor device data www.motorola.com/semiconductors figure 4. smoke timing diagram low supply test (internal) ired (pin 6) chamber test (internal) strobe (pin 4) 6 i/o (pin 7) silver, brass (not performed) (not performed) 10 10 9 ired 10% 90% 5 8 19 led (pin 11) 3 (as input) (as output) (as output) enable (internal) 15 12 11 no smoke pushbutton no smoke local smoke (remote smoke = don't care) remote smoke (no local smoke) notes: numbers refer to the ac electrical characteristics table. illustration is not to scale. 4 (extinguished) (continuously illuminated) 4 test f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
441 motorola sensor device data www.motorola.com/semiconductors 16 15 14 13 12 11 10 9 1 2 3 4 5 6 7 8 test lowsupply trip v ss r1 osc led feedback silver v dd ired i/o brass strobe detect c1 c2 horn x1 to other mc145011(s), escape light(s), auxiliary alarm(s), remote alarm(s), and/or autodialer ir current r13* 4.7 to 22 q1 2.2 m r5 h d3 visible led r7 47 k r6 100 k sw1 + + mc145011 pushbutton test r2 10 m 0.01 m f c6 h c3 1500 pf r1 100 k r3 470 r4 h 100 k 1 to 22 m f c4** c1 0.047 m f c2* 4700 pf r14 560 w r11 250 k d1 ir detector r8 8.2 k r9 2 5 k r10 4.7 k d2 ir emitter r12 1 k c5 100 m f h values for r4, r5, and c6 may differ depending on type of piezoelectric horn used. * c2 and r13 are used for coarse sensitivity adjustment. typical values are shown. 2 r9 is for fine sensitivity adjustment (optional). if fixed resistors are used, r8 = 12 k, r10 is 5.6 k to 10 k, and r9 is elim inated. when r9 is used, noise pickup is increased due to antenna effects. shielding may be required. ** c4 should be 22 m f if supply line resistance is high (up to 50 w ). c4 could be reduced to 1 m f when supply line resistance is < 30 w . v+ figure 5. typical application pin descriptions c1 (pin 1) a capacitor connected to this pin as shown in figure 5 determines the gain of the onchip photo amplifier during pushbutton test and chamber sensitivity test (high gain). the capacitor value is chosen such that the alarm is tripped from background reflections in the chamber during pushbutton test. a v 1 + (c1/10) where c1 is in pf. caution: the value of the closedloop gain should not exceed 10,000. c2 (pin 2) a capacitor connected to this pin as shown in figure 5 determines the gain of the onchip photo amplifier except during pushbutton or chamber sensitivity tests. a v 1 + (c2/10) where c2 is in pf. this gain increases about 10% during the ired pulse, after two consecutive local smoke detections. resistor r14 must be installed in series with c2. r14 [1/(12 c2 )] 680 where r14 is in ohms and c2 is in farads. detect (pin 3) this input to the highgain pulse amplifier is tied to the cathode of an external photodiode. the photodiode should have low capacitance and low dark leakage current. the diode must be shunted by a load resistor and is operated at zero bias. the detect input must be ac/dc decoupled from all other signals, v dd , and v ss . lead length and/or foil traces to this pin must be minimized, also. see figure 6. strobe (pin 4) this output provides a strobed, regulated voltage refer- enced to v dd . the temperature coefficient of this voltage is 0.2%/ c maximum from 10 to 60 c. the supplyvoltage coefficient (line regulation) is 0.2%/v maximum from 6 to 12 v. strobe is tied to external resistor string r8, r9, and r10. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
442 motorola sensor device data www.motorola.com/semiconductors v dd (pin 5) this pin is connected to the positive supply potential and may range from + 6 to + 12 v with respect to v ss . ired (pin 6) this output provides pulsed base current for external npn transistor q1 used as the infrared emitter driver. q1 must have b 100. at 10 ma, the temperature coefficient of the output voltage is typically + 0.5%/ c from 10 to 60 c. the supplyvoltage coefficient (line regulation) is 0.2%/v maxi- mum from 6 to 12 v. the ired pulse width (activehigh) is determined by external components r1 and c3. with a 100 k w /1500 pf combination, the nominal width is 105 m s. to minimize noise impact, ired is not active when the vis- ible led and horn outputs are active. ired is active near the end of strobe pulses for smoke tests, chamber sensitivity test, and pushbutton test. i/o (pin 7) this pin can be used to connect up to 40 units together in a wiredor configuration for common signaling. v ss is used as the return. an onchip current sink minimizes noise pick up during nonsmoke conditions and eliminates the need for an external pulldown resistor to complete the wiredor. remote units at lower supply voltages do not draw excessive current from a sending unit at a higher supply voltage. i/o can also be used to activate escape lights, auxiliary alarms, remote alarms, and/or autodialers. as an input, this pin feeds a positiveedgetriggered flip flop whose output is sampled nominally every 625 ms during standby (using the recommended component values). a localsmoke condition or the pushbuttontest mode forces this currentlimited output to source current. all input signals are ignored when i/o is sourcing current. i/o is disabled by the onchip poweron reset to elimi- nate nuisance signaling during battery changes or system powerup. if unused, i/o must be left unconnected. brass (pin 8) this half of the pushpull driver output is connected to the metal support electrode of a piezoelectric audio trans- ducer and to the hornstarting resistor. a continuous mod- ulated tone from the transducer is a smoke alarm indicating either local or remote smoke. a short beep or chirp is a trouble alarm indicating a low supply or degraded chamber sensitivity. silver (pin 9) this half of the pushpull driver output is connected to the ceramic electrode of a piezoelectric transducer and to the hornstarting capacitor. feedback (pin 10) this input is connected to both the feedback electrode of a selfresonating piezoelectric transducer and the hornstart- ing resistor and capacitor through currentlimiting resistor r4. if unused, this pin must be tied to v ss or v dd . led (pin 11) this activelow opendrain output directly drives an exter- nal visible led. the load for the lowsupply test is applied by this output. this lowsupply test is noncoincident with the smoke tests, chamber sensitivity test, pushbutton test, or any alarm signals. the led also provides a visual indication of the detector status as follows, assuming the component values shown in figure 5: standby (includes lowsupply and chamber sensitivity tests) e constantly illuminated local smoke e constantly extinguished remote smoke e constantly illuminated pushbutton test e constantly extinguished (system ok); constantly illuminated (system problem) osc (pin 12) this pin is used in conjunction with external resistor r2 (10 m w ) to v dd and external capacitor c3 (1500 pf) to v dd to form an oscillator with a nominal period of 10.5 ms. r1 (pin 13) this pin is used in conjunction with resistor r1 (100 k w ) to pin 12 and c3 (1500 pf, see pin 12 description) to determine the ired pulse width. with this rc combination, the nominal pulse width is 105 m s. v ss (pin 14) this pin is the negative supply potential and the return for the i/o pin. pin 14 is usually tied to ground. lowsupply trip (pin 15) this pin is connected to an external voltage which deter- mines the lowsupply alarm threshold. the trip voltage is obtained through a resistor divider connected between the v dd and led pins. the lowsupply alarm threshold voltage (in volts) (5r7/r6) + 5 where r6 and r7 are in the same units. test (pin 16) this input has an onchip pulldown device and is used to manually invoke a test mode. the pushbutton test mode is initiated by a high level at pin 16 (usually depression of a s.p.s.t. normallyopen pushbut- ton switch to v dd ). after one oscillator cycle, ired pulses approximately every 336 ms, regardless of the presence of smoke. additionally, the amplifier gain is increased by auto- matic selection of c1. therefore, the background reflections in the smoke chamber may be interpreted as smoke, gener- ating a simulatedsmoke condition. after the second ired pulse, a successful test activates the horndriver and i/o cir- cuits. the active i/o allows remote signaling for system test- ing. when the pushbutton test switch is released, the test input returns to v ss due to the onchip pulldown device. af- ter one oscillator cycle, the amplifier gain returns to normal, thereby removing the simulatedsmoke condition. after two additional ired pulses, less than a second, the ic exits the alarm mode and returns to standby timing. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
443 motorola sensor device data www.motorola.com/semiconductors calibration to facilitate checking the sensitivity and calibrating smoke detectors, the mc145011 can be placed in a calibration mode. in this mode, certain device pins are controlled/recon- figured as shown in table 1. to place the part in the calibra- tion mode, pin 16 (test) must be pulled below the v ss pin with 100 m a continuously drawn out of the pin for at least one cycle on the osc pin. to exit this mode, the test pin is floated for at least one osc cycle. in the calibration mode, the ired pulse rate is increased to one for every osc cycle. also, strobe is always active low. table 1. configuration of pins in the calibration mode description pin comment i/o 7 disabled as an output. forcing this pin high places the photo amp output on pin 1 or 2, as determined by lowsupply trip. the amp's output appears as pulses and is referenced to v dd . lowsupply trip 15 if the i/o pin is high, pin 15 controls which gain capacitor is used. low: normal gain, amp output on pin 1. high: supervisory gain, amp output on pin 2. feedback 10 driving this input high enables hysteresis (10% gain increase) in the photo amp; pin 15 must be low. osc 12 driving this input high brings the internal clock high. driving the input low brings the internal clock low. if desired, the rc network for the oscillator may be left intact; this allows the oscillator to run similar to the normal mode of operation. silver 9 this pin becomes the smoke comparator output. when the osc pin is toggling, positive pulses indicate that smoke has been detected. a static low level indicates no smoke. brass 8 this pin becomes the smoke integrator output. that is, 2 consecutive smoke detections are required for aono (static high level) and 2 consecutive nodetections for aoffo (static low level). notes: illustration is bottom view of layout using a dip. top view for soic layout is mirror image. optional potentiometer r9 is not included. drawing is not to scale. leads on d1, r11, r8, and r10 and their associated traces must be kept as short as possible. this practice minimizes noise pick up. pin 3 must be decoupled from all other traces. figure 6. recommended pcb layout do not run any additional traces in this region pin 8 pin 16 pin 9 pin 1 c1 r14 r11 d1 r8 mounted in chamber c2 r10 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
444 motorola sensor device data www.motorola.com/semiconductors !!
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" the cmos mc145012 is an advanced smoke detector component containing sophisticated verylowpower analog and digital circuitry. the ic is used with an infrared photoelectric chamber. detection is accomplished by sensing scattered light from minute smoke particles or other aerosols. when detection occurs, a pulsating alarm is sounded via onchip pushpull drivers and an external piezoelectric transducer. the variablegain photo amplifier allows direct interface to ir detectors (photodiodes). two external capacitors, c1 and c2, c1 being the larger, determine the gain settings. low gain is selected by the ic during most of the standby state. medium gain is selected during a localsmoke condition. high gain is used during pushbutton test. during standby, the special monitor circuit which periodically checks for degraded chamber sensitivity uses high gain also. the i/o pin, in combination with v ss , can be used to interconnect up to 40 units for common signaling. an onchip current sink provides noise immunity when the i/o is an input. a localsmoke condition activates the shortcircuit protected i/o driver, thereby signaling remote smoke to the interconnected units. additionally, the i/o pin can be used to activate escape lights, enable auxiliary or remote alarms, and/or initiate autodialers. while in standby, the lowsupply detection circuitry conducts periodic checks using a pulsed load current from the led pin. the trip point is set using two external resistors. the supply for the mc145012 can be a 9 v battery. a visible led flash accompanying a pulsating audible alarm indicates a localsmoke condition. a pulsating audible alarm with no led flash indicates a remotesmoke condition. a beep or chirp occurring virtually simultaneously with an led flash indicates a lowsupply condition. a beep or chirp occurring halfway between led flashes indicates degraded chamber sensitivity. a lowsupply condition does not affect the smoke detection capability if v dd 6 v. therefore, the lowsupply condition and degraded chamber sensitivity can be further distinguished by performing a pushbutton (chamber) test. ? circuit is designed to operate in smoke detector systems that comply with ul217 and ul268 specifications ? operating voltage range: 6 to 12 v ? operating temperature range: 10 to 60 c ? average supply current: 8 m a ? i/o pin allows units to be interconnected for common signalling ? poweron reset places ic in standby mode (nonalarm state) ? electrostatic discharge (esd) and latch up protection circuitry on all pins ? chip complexity: 2000 fets, 12 npns, 16 resistors, and 10 capacitors ? supports nfpa 72, ansi s3.41, and iso 8201 audible emergency evacuation signals ? ideal for batterypowered applications semiconductor technical data p suffix plastic dip case 64808 pin assignment 16 15 14 13 12 11 10 9 1 2 3 4 5 6 7 8 c1 c2 detect strobe v dd ired i/o brass test lowsupply trip v ss r1 osc led feedback silver ordering information mc145012p plastic dip mc145012dw soic package 1 16 dw suffix soic package case 751g03 1 16 rev 4 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
445 motorola sensor device data www.motorola.com/semiconductors block diagram + + detect osc r1 test strobe lowsupply trip 3 12 13 16 4 15 2 1 c1 c2 osc amp comp comp alarm logic temporal pattern horn modulator and driver v dd 5 v ref timing logic v dd 3.5 v ref zero gain low supply smoke gate on/off gate on/off 8 9 10 6 11 7 pin 5 = v dd pin 14 = v ss led ired feedback silver brass i/o maximum ratings* (voltages referenced to v ss ) symbol parameter value unit v dd dc supply voltage 0.5 to +12 v v in dc input voltage c1, c2, detect osc, lowsupply trip i/o feedback test 0.25 to v dd +0.25 0.25 to v dd +0.25 0.25 to v dd +10 15 to +25 1.0 to v dd +0.25 v i in dc input current, per pin 10 ma i out dc output current, per pin 25 ma i dd dc supply current, v dd and v ss pins +25 / 150 ma p d power dissipation in still air, 5 seconds continuous 1200** 350*** mw t stg storage temperature 55 to +125 c t l lead temperature, 1 mm from case for 10 seconds 260 c * maximum ratings are those values beyond which damage to the device may occur. functional operation should be restricted to the limits in the electrical characteristics tables. ** derating: 12 mw/ c from 25 to 60 c. *** derating: 3.5 mw/ c from 25 to 60 c. this device contains protection circuitry to guard against damage due to high static voltages or electric fields. however, prec autions must be taken to avoid applications of any voltage higher than maximum rated voltages to this highimpedance circuit. for proper ope ration, v in and v out should be constrained to the range v ss (v in or v out ) v dd except for the i/o, which can exceed v dd , and the test input, which can go below v ss . unused inputs must always be tied to an appropriate logic voltage level (e.g., either v ss or v dd ). unused outputs and/or an unused i/o must be left open. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
446 motorola sensor device data www.motorola.com/semiconductors electrical characteristics (voltages referenced to v ss , t a = 10 to 60 c unless otherwise indicated) symbol parameter test condition v dd v min max unit v dd power supply voltage range e 6 12 v v th supply threshold voltage, lowsupply alarm lowsupply trip: v in = v dd /3 e 6.5 7.8 v i dd average operating supply current (per package) (does not include current through d3ir emitter) standby configured per figure 5 12.0 e 8.0 m a i dd peak supply current (per package) (does not include ired current into base of q1) during strobe on, ired off configured per figure 5 12.0 e 2.0 ma o f q1) during strobe on, ired on configured per figure 5 12.0 e 3.0 v il lowlevel input voltage i/o feedback test 9.0 9.0 9.0 e e e 1.5 2.7 7.0 v v ih highlevel input voltage i/o feedback test 9.0 9.0 9.0 3.2 6.3 8.5 e e e v i in input current osc, detect lowsupply trip feedback v in = v ss or v dd v in = v ss or v dd v in = v ss or v dd 12.0 12.0 12.0 e e e 100 100 100 na i il lowlevel input current test v in = v ss 12.0 100 1 m a i ih pulldown current test i/o v in = v dd no local smoke, v in = v dd no local smoke, v in = 17 v 9.0 9.0 12.0 0.5 25 e 10 100 140 m a v ol lowlevel output voltage led silver, brass i out = 10 ma i out = 16 ma 6.5 6.5 e e 0.6 1.0 v v oh highlevel output voltage silver, brass i out = 16 ma 6.5 5.5 e v v out output voltage strobe (for line regulation, see pin descriptions) inactive, i out = 1 m a active, i out = 100 m a to 500 m a (load regulation) e 9.0 v dd 0.1 v dd 4.4 e v dd 5.6 v ired inactive, i out = 1 m a active, i out = 6 ma (load regulation) e 9.0 e 2.25* 0.1 3.75* i oh highlevel output current i/o local smoke, v out = 4.5 v 6.5 4 e ma local smoke, v out = v ss (short circuit current) 12.0 e 16 i oz offstate output leakage current led v out = v ss or v dd 12.0 e 1 m a v ic common mode c1, c2, detect voltage range local smoke, pushbutton test, or chamber sensitivity test e v dd 4 v dd 2 v v ref smoke comparator internal reference voltage local smoke, pushbutton test, or chamber sensitivity test e v dd 3.08 v dd 3.92 v *t a = 25 c only. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
447 motorola sensor device data www.motorola.com/semiconductors ac electrical characteristics (reference timing diagram figures 3 and 4) (t a = 25 c, v dd = 9.0 v, component values from figure 5: r1 = 100.0 k w , c3 = 1500.0 pf, r2 = 7.5 m w ) no. symbol parameter test condition clocks min* typ** max* unit 1 1/f osc oscillator period freerunning sawtooth measured at pin 12 1 7.0 7.9 8.6 ms 2 t led led pulse period no local smoke, and no remote smoke 4096 28.8 32.4 35.2 s 3 remote smoke, but no local smoke e extinguished 4 local smoke 64 0.45 0.5 0.55 5 pushbutton test 64 0.45 0.5 0.55 6 t w(led) , t w(stb) led pulse width and strobe pulse width 1 7.0 e 8.6 ms 7 t ired ired pulse period smoke test 1024 7.2 8.1 8.8 s 8 t ired ired pulse period chamber sensitivity test, without local smoke 4096 28.8 32.4 35.2 s 9 pushbutton test 128 0.9 1 1.1 10 t w(ired) ired pulse width t f * 94 116 m s 11 t r ired rise time e e 30 m s 12 t f ired fall time e e 200 13 t on silver and brass temporal mdlti pl width 64 0.45 0.5 0.55 s 14 t off m o d u l at i on p u l se wid t h 0.45 0.5 0.55 15 t offd 192 1.35 1.52 1.65 16 t ch silver and brass chirp pulse period low supply or degraded chamber sensitivity 4096 28.8 32.4 35.2 s 17 t wch silver and brass chirp pulse width 1 7.0 7.9 8.6 ms 18 t rr rising edge on i/o to smoke alarm response time remote smoke, no local smoke e e 2 ! e s 19 t stb strobe out pulse period smoke test 1024 7.2 8.1 8.8 s 20 chamber sensitivity test, without local smoke 4096 28.8 32.4 35.2 21 low supply test, without local smoke 4096 28.8 32.4 35.2 22 pushbutton test e e 1 e * oscillator period t (= t r + t f ) is determined by the external components r1, r2, and c3 where t r = (0.6931) r 2 * c 3 and t f = (0.6931) r 1 * c 3 . the other timing characteristics are some multiple of the oscillator timing as shown in the table. the timing shown should acco modate the nfpa 72, ansi s3.41, and iso 8201 audible emergency evacuation signals. ** typicals are not guaranteed. ! time is typical e depends on what point in cycle signal is applied. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
448 motorola sensor device data www.motorola.com/semiconductors figure 1. ac characteristics versus supply pulse width of ired period or pulse width of other parameters ac parameter (normalized to 9.0 v value) v dd , power supply voltage (v) 1.02 0.98 0.96 1.00 1.04 6.0 7.0 8.0 9.0 10.0 11.0 12.0 t a = 25 c figure 2a. ac characteristics versus temperature note: includes external component variations. see figure 2b. pulse width of ired period or pulse width of other parameters ac parameter (normalized to 25 c value) t a , ambient temperature ( c) 10 0 10 20 30 40 50 60 1.02 1.01 0.99 0.98 1.00 v dd = 9.0 v figure 2. figure 2b. rc component variation over temperature note: these components were used to generate figure 2a. 7.5 m w carbon composition 100 k w metal film 1500 pf dipped mica component value (normalized to 25 c value) t a , ambient temperature ( c) 10 0 10 20 30 40 50 60 1.03 1.02 1.01 1.00 0.99 0.98 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
449 motorola sensor device data www.motorola.com/semiconductors low supply test (internal) photo sample (internal) figure 3. typical standby timing chamber test (internal) 8 osc (pin 12) 1 led (pin 11) silver, brass (internal) enable 2 16 16 poweron reset no low supply e chamber sensitivity ok chirps indicate low supply chirps indicate degraded chamber sensitivity ired (pin 6) strobe (pin 4) 7 7 19 20 21 6 17 21 notes: numbers refer to the ac electrical characteristics table. illustration is not to scale. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
450 motorola sensor device data www.motorola.com/semiconductors figure 4. typical local smoke timing low supply test (internal) ired (pin 6) chamber test (internal) strobe (pin 4) 7 i/o (pin 7) silver, brass (not performed) (not performed) 12 11 10 ired 10% 90% 18 6 9 22 led (pin 11) 6 5 3 (no pulses) (as input) (as output) (as output) enable (internal) 18 13 14 15 no smoke pushbutton test no smoke local smoke (remote smoke = don't care) remote smoke (no local smoke) 4 notes: numbers refer to the ac electrical characteristics table. illustration is not to scale. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
451 motorola sensor device data www.motorola.com/semiconductors 16 15 14 13 12 11 10 9 1 2 3 4 5 6 7 8 test lowsupply trip v ss r1 osc led feedback silver v dd ired i/o brass strobe detect c1 c2 horn x1 to other mc145012(s), escape light(s), auxiliary alarm(s), remote alarm(s), and/or autodialer ir current r13* 4.7 to 22 q1 2.2 m r5 # d4 visible led r7 47 k r6 100 k sw1 + + mc145012 reverse polarity protection circuit pushbutton test r2 7.5 m 0.01 m f c6 # c3 1500 pf r1 100 k r3 470 r4 # 100 k 9 v b1 d1 1 to 22 m f c4** c1 0.047 m f c2* 4700 pf r14 560 w r11 250 k d2 ir detector r8 8.2 k r9 2 5 k r10 4.7 k d3 ir emitter r12 1 k c5 100 m f # values for r4, r5, and c6 may differ depending on type of piezoelectric horn used. * c2 and r13 are used for coarse sensitivity adjustment. typical values are shown. 2r9 is for fine sensitivity adjustment (optional). if fixed resistors are used, r8 = 12 k, r10 is 5.6 k to 10 k, and r9 is elim inated. when r9 is used, noise pickup is increased due to antenna effects. shielding may be required. **c4 should be 22 m f if b1 is a carbon battery. c4 could be reduced to 1 m f when an alkaline battery is used. figure 5. typical batterypowered application pin descriptions c1 (pin 1) a capacitor connected to this pin as shown in figure 5 determines the gain of the onchip photo amplifier during pushbutton test and chamber sensitivity test (high gain). the capacitor value is chosen such that the alarm is tripped from background reflections in the chamber during pushbutton test. a v 1 + (c1/10) where c1 is in pf. caution: the value of the closedloop gain should not exceed 10,000. c2 (pin 2) a capacitor connected to this pin as shown in figure 5 determines the gain of the onchip photo amplifier except during pushbutton or chamber sensitivity tests. a v 1 + (c2/10) where c2 is in pf. this gain increases about 10% during the ired pulse, after two consecutive local smoke detections. resistor r14 must be installed in series with c2. r14 [1/(12 c2 )] 680 where r14 is in ohms and c2 is in farads. detect (pin 3) this input to the highgain pulse amplifier is tied to the cathode of an external photodiode. the photodiode should have low capacitance and low dark leakage current. the diode must be shunted by a load resistor and is operated at zero bias. the detect input must be ac/dc decoupled from all other signals, v dd , and v ss . lead length and/or foil traces to this pin must be minimized, also. see figure 6. strobe (pin 4) this output provides a strobed, regulated voltage refer- enced to v dd . the temperature coefficient of this voltage is 0.2%/ c maximum from 10 to 60 c. the supplyvoltage coefficient (line regulation) is 0.2%/v maximum from 6 to 12 v. strobe is tied to external resistor string r8, r9, and r10. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
452 motorola sensor device data www.motorola.com/semiconductors v dd (pin 5) this pin is connected to the positive supply potential and may range from + 6 to + 12 v with respect to v ss caution: in batterypowered applications, reversepolar- ity protection must be provided externally. ired (pin 6) this output provides pulsed base current for external npn transistor q1 used as the infrared emitter driver. q1 must have b 100. at 10 ma, the temperature coefficient of the output voltage is typically + 0.5%/ c from 10 to 60 c. the supplyvoltage coefficient (line regulation) is 0.2%/v maxi- mum from 6 to 12 v. the ired pulse width (activehigh) is determined by external components r1 and c3. with a 100 k w /1500 pf combination, the nominal width is 105 m s. to minimize noise impact, ired is not active when the vis- ible led and horn outputs are active. ired is active near the end of strobe pulses for smoke tests, chamber sensitivity test, and pushbutton test. i/o (pin 7) this pin can be used to connect up to 40 units together in a wiredor configuration for common signaling. v ss is used as the return. an onchip current sink minimizes noise pick up during nonsmoke conditions and eliminates the need for an external pulldown resistor to complete the wiredor. remote units at lower supply voltages do not draw excessive current from a sending unit at a higher supply voltage. i/o can also be used to activate escape lights, auxiliary alarms, remote alarms, and/or autodialers. as an input, this pin feeds a positiveedgetriggered flip flop whose output is sampled nominally every 1 second dur- ing standby (using the recommended component values). a localsmoke condition or the pushbuttontest mode forces this currentlimited output to source current. all input signals are ignored when i/o is sourcing current. i/o is disabled by the onchip poweron reset to eliminate nuisance signaling during battery changes or system power up. if unused, i/o must be left unconnected. brass (pin 8) this half of the pushpull driver output is connected to the metal support electrode of a piezoelectric audio transducer and to the hornstarting resistor. a continuous modulated tone from the transducer is a smoke alarm indicating either local or remote smoke. a short beep or chirp is a trouble alarm indicating a low supply or degraded chamber sensitiv- ity. silver (pin 9) this half of the pushpull driver output is connected to the ceramic electrode of a piezoelectric transducer and to the hornstarting capacitor. feedback (pin 10) this input is connected to both the feedback electrode of a selfresonating piezoelectric transducer and the hornstart- ing resistor and capacitor through currentlimiting resistor r4. if unused, this pin must be tied to v ss or v dd . led (pin 11) this activelow opendrain output directly drives an exter- nal visible led at the pulse rates indicated below. the pulse width is equal to the osc period. the load for the lowsupply test is applied by this output. this lowsupply test is noncoincident with the smoke tests, chamber sensitivity test, pushbutton test, or any alarm sig- nals. the led also provides a visual indication of the detector status as follows, assuming the component values shown in figure 5: standby (includes lowsupply and chamber sensitivity tests) e pulses every 32.4 seconds (typical) local smoke e pulses every 0.51 seconds (typical) remote smoke e no pulses pushbutton test e pulses every 0.51 seconds (typical) osc (pin 12) this pin is used in conjunction with external resistor r2 (7.5 m w ) to v dd and external capacitor c3 (1500 pf) to v dd to form an oscillator with a nominal period of 7.9 ms (typical). r1 (pin 13) this pin is used in conjunction with resistor r1 (100 k w ) to pin 12 and c3 (1500 pf, see pin 12 description) to determine the ired pulse width. with this rc combination, the nominal pulse width is 105 m s. v ss (pin 14) this pin is the negative supply potential and the return for the i/o pin. pin 14 is usually tied to ground. lowsupply trip (pin 15) this pin is connected to an external voltage which deter- mines the lowsupply alarm threshold. the trip voltage is obtained through a resistor divider connected between the v dd and led pins. the lowsupply alarm threshold voltage (in volts) (5r7/r6) + 5 where r6 and r7 are in the same units. test (pin 16) this input has an onchip pulldown device and is used to manually invoke a test mode. the pushbutton test mode is initiated by a high level at pin 16 (usually depression of a s.p.s.t. normallyopen pushbut- ton switch to v dd ). after one oscillator cycle, ired pulses approximately every 1.0 second, regardless of the presence of smoke. additionally, the amplifier gain is increased by automatic selection of c1. therefore, the background reflec- tions in the smoke chamber may be interpreted as smoke, generating a simulatedsmoke condition. after the second ired pulse, a successful test activates the horndriver and i/o circuits. the active i/o allows remote signaling for system testing. when the pushbutton test switch is released, the test input returns to v ss due to the onchip pulldown device. after one oscillator cycle, the amplifier gain returns to normal, thereby removing the simulatedsmoke condition. after two additional ired pulses, less than three seconds, the ic exits the alarm mode and returns to standby timing. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
453 motorola sensor device data www.motorola.com/semiconductors calibration to facilitate checking the sensitivity and calibrating smoke detectors, the mc145012 can be placed in a calibration mode. in this mode, certain device pins are controlled/recon- figured as shown in table 1. to place the part in the calibra- tion mode, pin 16 (test) must be pulled below the v ss pin with 100 m a continuously drawn out of the pin for at least one cycle on the osc pin. to exit this mode, the test pin is floated for at least one osc cycle. in the calibration mode, the ired pulse rate is increased to one for every osc cycle. also, strobe is always active low. table 1. configuration of pins in the calibration mode description pin comment i/o 7 disabled as an output. forcing this pin high places the photo amp output on pin 1 or 2, as determined by lowsupply trip. the amp's output appears as pulses and is referenced to v dd etc. lowsupply trip 15 if the i/o pin is high, pin 15 controls which gain capacitor is used. low: normal gain, amp output on pin 1. high: supervisory gain, amp output on pin 2. feedback 10 driving this input high enables hysteresis (10% gain increase) in the photo amp; pin 15 must be low. osc 12 driving this input high brings the internal clock high. driving the input low brings the internal clock low. if desired, the rc network for the oscillator may be left intact; this allows the oscillator to run similar to the normal mode of operation. silver 9 this pin becomes the smoke comparator output. when the osc pin is toggling, positive pulses indicate that smoke has been detected. a static low level indicates no smoke. brass 8 this pin becomes the smoke integrator output. that is, 2 consecutive smoke detections are required for aono (static high level) and 2 consecutive nodetections for aoffo (static low level). notes: illustration is bottom view of layout using a dip. top view for soic layout is mirror image. optional potentiometer r9 is not included. drawing is not to scale. leads on d2, r11, r8, and r10 and their associated traces must be kept as short as possible. this practice minimizes noise pick up. pin 3 must be decoupled from all other traces. figure 6. recommended pcb layout do not run any additional traces in this region pin 8 pin 16 pin 9 pin 1 c1 r14 r11 d2 r8 mounted in chamber c2 r10 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
454 motorola sensor device data www.motorola.com/semiconductors lowpower cmos " !
the mc145017, when used with an ionization chamber and a small number of external components, will detect smoke. when smoke is sensed, an alarm is sounded via an external piezoelectric transducer and internal drivers. this circuit is designed to operate in smoke detector systems that comply with ul217 and ul268 specifications. ? ionization type with onchip fet input comparator ? piezoelectric horn driver ? guard outputs on both sides of detect input ? inputproduction diodes on the detect input ? lowbattery trip point, internally set, can be altered via external resistor ? detect threshold, internally set, can be altered via external resistor ? pulse testing for low battery uses led for battery loading ? comparator outputs for detect and low battery ? internal reverse battery protection ? supports nfpa 72, ansi 53.41, and iso 8201 audible emergency evacuation signals maximum ratings* (voltages referenced to v ss ) rating symbol value unit dc supply voltage v dd 0.5 to + 15 v input voltage, all inputs except pin 8 v in 0.25 to v dd + 0.25 v dc current drain per input pin, except pin 15 = 1 ma i 10 ma dc current drain per output pin i 30 ma operating temperature range t a 10 to + 60 c storage temperature range t stg 55 to + 125 c reverse battery time t rb 5.0 s * maximum ratings are those values beyond which damage to the device may occur. this device contains circuitry to protect the inputs against damage due to high static voltages or electric fields; however, it is advised that normal precautions be taken to avoid application of any voltage higher than maximum rated voltages to this high impedance circuit. for proper operation it is recommended that v in and v out be constrained to the range v ss (v in or v out ) v dd . semiconductor technical data p suffix plastic dip case 64808 pin assignment (16 pin dip) 16 15 14 13 12 11 10 9 1 2 3 4 5 6 7 8 detect comp. out n/c low v set low v comp. out led v dd timing resistor feedback guard hiz detect input guard loz sensitivity set osc capacitor silver brass v ss ordering information mc145017p plastic dip 1 16 rev 4 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
455 motorola sensor device data www.motorola.com/semiconductors recommended operating conditions (voltages referenced to v ss ) parameter symbol value unit supply voltage v dd 9.0 v timing capacitor e 0.1 m f timing resistor e 8.2 m w battery load (resistor or led) e 10 ma electrical characteristics (voltages referenced to v ss , ta = 25 c) characteristic symbol v dd v dc min typ max unit operating voltage v dd e 6.0 e 12 v output voltage piezoelectric horn drivers (i oh = 16 ma) comparators (i oh = 30 m a) piezoelectric horn drivers (i ol = +16 ma) comparators (i ol = +30 m a) v oh v ol 7.2 9.0 7.2 9.0 6.3 8.5 e e e 8.8 e 0.1 e e 0.9 0.5 v v output voltage e led driver, i ol = 10 ma v ol 7.2 e e 3.0 v output impedance, active guard pin 14 pin 16 loz hiz 9.0 9.0 e e e e 10 1000 k w operating current (r bias = 8.2 m w ) i dd 9.0 12.0 e e 3.2 e 7.0 10.0 m a input current e detect (40% r.h.) i in 9.0 e e 1.0 pa input current, pin 8 i in 9.0 e e 0.1 m a input current @ 50 c, pin 15 i in e e e 6.0 pa internal set voltage low battery sensitivity v low v set 9.0 e 7.2 47 e 50 7.8 53 v %v dd hysteresis v hys 9.0 75 100 150 mv offset voltage (measured at vin = vdd/2) active guard detect comparator v os 9.0 9.0 e e e e 100 50 mv input voltage range, pin 8 v in e vss 10 e vdd + 10 v input capacitance c in e e 5.0 e pf common mode voltage range, pin 15 v cm e 0.6 e vdd 2 v # data labelled atyp'' is not to be used for design purposes but is intended as an indication of the ic's potential performance . f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
456 motorola sensor device data www.motorola.com/semiconductors timing parameters (c = 0.1 m f, r bias = 8.2 m w , v dd = 9.0 v, t a = 25 c, see figure 6) characteristics symbol min max units oscillator period no smoke smoke t ci 1.46 37.5 1.85 45.8 s ms oscillator rise time t r 10.1 12.3 ms horn output on time (during smoke) off time pw on pw off 450 450 550 550 ms ms led output between pulses on time t led pw on 35.0 10.1 44.5 12.3 s ms horn output on time (during low battery) between pulses t on t off 10.1 35.0 12.3 44.5 ms s figure 1. block diagram + v dd latch low battery comp. oscillator timer latch + v dd 80 k 3 1045 k 7 12 1 13 1125 k + 15 detect input 14 loz active guard 16 hiz v dd 4 v dd 8 piezoelectric horn driver 11 10 5 led driver v dd 6 9 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
457 motorola sensor device data www.motorola.com/semiconductors figure 2. typical led output iv characteristic figure 3. typical comparator output iv characteristic figure 4. typical p horn driver output iv characteristic 0 1234 56 7 8910 0.1 1.0 10.0 100 . 0 t a = 25 c v ds , drain to source voltage (vdc) v dd = 7.2 vdc v dd = 9.0 vdc 012345678910 1.0 10.0 100.0 1000.0 d i , drain current (ma) t a = 25 c v ds , drain to source voltage (vdc) pch source current v dd = 7.2 vdc v dd = 9.0 vdc 012345678910 1.0 10.0 100.0 1000.0 d i , drain current (ma) t a = 25 c v ds , drain to source voltage (vdc) nch sink current v dd = 7.2 vdc v dd = 9.0 vdc 012 34 56 78910 0.01 0.1 1.0 10 . 0 d i , drain current (ma) t a = 25 c v ds , drain to source voltage (vdc) pch source and nch sink current v dd = 9.0 vdc or 7.2 vdc d i , drain current (ma) f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
458 motorola sensor device data www.motorola.com/semiconductors device operation timing the internal oscillator of the mc145017 operates with a period of 1.65 seconds during nosmoke conditions. each 1.65 seconds, internal power is applied to the entire ic and a check is made for smoke, except during led pulse, low bat- tery alarm chirp, or horn modulation (in smoke). every 24 clock cycles a check is made for low battery by comparing v dd to an internal zener voltage. since very small currents are used in the oscillator, the oscillator capacitor should be of a low leakage type. detect circuitry if smoke is detected, the oscillator period becomes 41.67 ms and the piezoelectric horn oscillator circuit is enabled. the horn output is modulated 500 ms on, 500 ms off. during the off time, smoke is again checked and will in- hibit further horn output if no smoke is sensed. during smoke conditions the low battery alarm is inhibited, but the led pulses at a 1.0 hz rate. an active guard is provided on both pins adjacent to the detect input. the voltage at these pins will be within 100 mv of the input signal. this will keep surface leakage currents to a minimum and provide a method of measuring the input volt- age without loading the ionization chamber. the active guard op amp is not power strobed and thus gives constant protec- tion from surface leakage currents. pin 15 (the detect input) has internal diode protection against static damage. sensitivity/low battery thresholds both the sensitivity threshold and the low battery voltage levels are set internally by a common voltage divider (please see figure 1) connected between v dd and v ss . these volt- ages can be altered by external resistors connected from pins 3 or 13 to either v dd or v ss . there will be a slight inter- action here due to the common voltage divider network. the sensitivity threshold can also be set by adjusting the smoke chamber ionization source. test mode since the internal op amps and comparators are power strobed, adjustments for sensitivity or low battery level could be difficult and/or timeconsuming. by forcing pin 12 to v ss , the power strobing is bypassed and the outputs, pins 1 and 4, constantly show smoke/no smoke and good battery/low battery, respectively. pin 1 = v dd for smoke and pin 4 = v dd for low battery. in this mode and during the 10 ms power strobe, chip current rises to approximately 50 m a. led pulse the 9volt battery level is checked every 40 seconds dur- ing the led pulse. the battery is loaded via a 10 ma pulse for 11.6 ms. if the led is not used, it should be replaced with an equivalent resistor such that the battery loading remains at 10 ma. hysteresis when smoke is detected, the resistor/divider network that sets sensitivity is altered to increase sensitivity. this yields approximately 100 mv of hysteresis and reduces false triggering. figure 5. typical application as ionization smoke detector mc145017 116 2 3 4 5 6 7 8 15 14 13 12 11 10 9 330 w 8.2 m w + 9 v 0.1 m f 1.5 m w * 0.001 m f 220 k w * 0.1 m f 1 m 1 m test *note: component values may change depending on type of piezoelectric horn used. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
459 motorola sensor device data www.motorola.com/semiconductors figure 6. mc145017 timing diagram osc pin 12 smoke n y low bat y n hyst pin 13 horn on off led off on 234567 9 8 no smoke, low battery 1 no smk no low bat low battery chirp osc pin 12 smoke n y no smk 23 24 1 6 12 18 24 smoke latch alarm condition ( 100 mv level shift) nfpa mod low bat y n horn on off led off on (note 1) 24 clocks 24 clocks notes: 1. horn modulation is selfcompleting. when going from smoke to no smoke, the alarm condition will terminate only when horn is o ff. 2. comparators are strobed once per cycle (1.65 sec for no smoke, 40 msec for smoke). figure 7. horn modulation nfpa72: temporal horn modulation pattern traditional 4/6 horn modulation pattern 0.5 sec 0.5 sec 0.5 sec 0.5 sec 0.5 sec 1.5 sec 167 msec 83 msec f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
460 motorola sensor device data www.motorola.com/semiconductors lowpower cmos " !
the mc145018, when used with an ionization chamber and a small number of external components, will detect smoke. when smoke is sensed, an alarm is sounded via an external piezoelectric transducer and internal drivers. this circuit is designed to operate in smoke detector systems that comply with ul217 and ul268 specifications. ? ionization type with onchip fet input comparator ? piezoelectric horn driver ? guard outputs on both sides of detect input ? inputprotection diodes on the detect input ? lowbattery trip point, internally set, can be altered via external resistor ? detect threshold, internally set, can be altered via external resistor ? pulse testing for low battery uses led for battery loading ? comparator output for detect ? internal reverse battery protection ? strobe output for external trim resistors ? i/o pin allows up to 40 units to be connected for common signaling ? supports nfpa 72, ansi 53.41, and iso 8201 audible emergency evacuation signals ? poweron reset places ic in standby mode maximum ratings* (voltages referenced to v ss ) rating symbol value unit dc supply voltage v dd 0.5 to + 15 v input voltage, all inputs except pin 8 v in 0.25 to v dd + 0.25 v dc current drain per input pin, except pin 15 = 1 ma i 10 ma dc current drain per output pin i 30 ma operating temperature range t a 10 to + 60 c storage temperature range t stg 55 to + 125 c reverse battery time t rb 5.0 s * maximum ratings are those values beyond which damage to the device may occur. this device contains circuitry to protect the inputs against damage due to high static voltages or electric fields; however, it is advised that normal precautions be taken to avoid application of any voltage higher than maximum rated voltages to this high impedance circuit. for proper operation it is recommended that v in and v out be constrained to the range v ss (v in or v out ) v dd . semiconductor technical data p suffix plastic dip case 64808 pin assignment (16 pin dip) 16 15 14 13 12 11 10 9 1 2 3 4 5 6 7 8 detect comp. out i/o low v set strobe out led v dd timing resistor feedback guard hiz detect input guard loz sensitivity set osc capacitor silver brass v ss ordering information mc145018p plastic dip 1 16 rev 3 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
461 motorola sensor device data www.motorola.com/semiconductors recommended operating conditions (voltages referenced to v ss ) parameter symbol value unit supply voltage v dd 9.0 v timing capacitor e 0.1 m f timing resistor e 8.2 m w battery load (resistor or led) e 10 ma electrical characteristics (voltages referenced to v ss , ta = 25 c) characteristic symbol v dd v dc min typ max unit operating voltage v dd e 6.0 e 12 v output voltage piezoelectric horn drivers (i oh = 16 ma) comparators (i oh = 30 m a) piezoelectric horn drivers (i ol = + 16 ma) comparators (i ol = +30 m a) v oh v ol 7.2 9.0 7.2 9.0 6.3 8.5 e e e 8.8 e 0.1 e e 0.9 0.5 v v output voltage e led driver, i ol = 10 ma v ol 7.2 e e 3.0 v output impedance, active guard pin 14 pin 16 loz hiz 9.0 9.0 e e e e 10 1000 k w operating current (r bias = 8.2 m w ) i dd 9.0 12.0 e e 5.0 e 9.0 12.0 m a input current e detect (40% r.h.) i in 9.0 e e 1.0 pa input current, pin 8 i in 9.0 e e 0.1 m a input current @ 50 c, pin 15 i in e e e 6.0 pa internal set voltage low battery sensitivity v low v set 9.0 e 7.2 47 e 50 7.8 53 v %v dd hysteresis v hys 9.0 75 100 150 mv offset voltage (measured at vin = vdd/2) active guard detect comparator v os 9.0 9.0 e e e e 100 50 mv input voltage range, pin 8 v in e vss 10 e vdd + 10 v input capacitance c in e e 5.0 e pf common mode voltage range, pin 15 v cm e 0.6 e vdd 2 v i/o current, pin 2 input, v ih = vdd 2 output, v oh = vdd 2 i ih i oh e e 25 4.0 e e 100 16 m a ma # data labelled atyp'' is not to be used for design purposes but is intended as an indication of the ic's potential performance . f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
462 motorola sensor device data www.motorola.com/semiconductors timing parameters (c = 0.1 m f, r bias = 8.2 m w , v dd = 9.0 v, t a = 25 c, see figure 6) characteristics symbol min max units oscillator period no smoke smoke t ci 1.46 37.5 1.85 45.8 s ms oscillator rise time t r 10.1 12.3 ms horn output on time (during smoke) off time pw on pw off 450 450 550 550 ms ms led output between pulses on time t led pw on 35.0 10.1 44.5 12.3 s ms horn output on time (during low battery) between pulses t on t off 10.1 35.0 12.3 44.5 ms s low battery comparator figure 1. block diagram v dd 45 k 3 low v set 1 detect comp. out 280 k 13 sensitivity set 325 k strobe out 4 v dd + + 15 detect input detect comparator guard amp + loz 14 16 alarm logic poweron reset osc and timing i/o 2 11 feedback 8 10 silver brass 5 led v dd = pin 6 v ss = pin 9 12 7 v dd to other units hiz v dd f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
463 motorola sensor device data www.motorola.com/semiconductors 012345678910 0.1 1.0 10.0 100 . 0 t a = 25 c v ds , drain to source voltage (vdc) v dd = 7.2 vdc v dd = 9.0 vdc 0 1234 56 7 8910 1.0 10.0 100.0 1000.0 d i , drain current (ma) t a = 25 c v ds , drain to source voltage (vdc) pch source current v dd = 7.2 vdc v dd = 9.0 vdc 0 1234 56 7 8910 1.0 10.0 100.0 1000.0 d i , drain current (ma) t a = 25 c v ds , drain to source voltage (vdc) nch sink current v dd = 7.2 vdc v dd = 9.0 vdc 012 34 56 78910 0.01 0.1 1.0 10 . 0 d i , drain current (ma) t a = 25 c v ds , drain to source voltage (vdc) pch source and nch sink current v dd = 9.0 vdc or 7.2 vdc d i , drain current (ma) figure 2. typical led output iv characteristic figure 3. typical comparator output iv characteristic figure 4. typical p horn driver output iv characteristic f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
464 motorola sensor device data www.motorola.com/semiconductors device operation timing the internal oscillator of the mc145018 operates with a period of 1.65 seconds during nosmoke conditions. each 1.65 seconds, internal power is applied to the entire ic and a check is made for smoke, except during led pulse, low bat- tery alarm chirp, or horn modulation (in smoke). every 24 clock cycles a check is made for low battery by comparing v dd to an internal zener voltage. since very small currents are used in the oscillator, the oscillator capacitor should be of a low leakage type. detect circuitry if smoke is detected, the oscillator period becomes 41.67 ms and the piezoelectric horn oscillator circuit is enabled. the horn output is modulated 500 ms on, 500 ms off. during the off time, smoke is again checked and will inhibit further horn output if no smoke is sensed. during local smoke conditions the low battery alarm is inhibited, but the led pulses at a 1.0 hz rate. in remote smoke, the led is inhibited as well. an active guard is provided on both pins adjacent to the detect input. the voltage at these pins will be within 100 mv of the input signal. this will keep surface leakage currents to a minimum and provide a method of measuring the input volt- age without loading the ionization chamber. the active guard op amp is not power strobed and thus gives constant protec- tion from surface leakage currents. pin 15 (the detect input) has internal diode protection against static damage. interconnect the i/o (pin 2), in combination with v ss , is used to inter- connect up to 40 remote units for common signaling. a local smoke condition activates a current limited output driver, thereby signaling remote smoke to interconnected units. a small current sink improves noise immunity during non smoke conditions. remote units at lower voltages do not draw excessive current from a sending unit at a higher volt- age. the i/o is disabled for three oscillator cycles after power up, to eliminate false alarming of remote units when the bat- tery is changed. sensitivity/low battery thresholds both the sensitivity threshold and the low battery voltage levels are set internally by a common voltage divider (see figure 1) connected between v dd and v ss . these voltages can be altered by external resistors connected from pins 3 or 13 to either v dd or v ss . there will be a slight interaction here due to the common voltage divider network. the sensitivity threshold can also be set by adjusting the smoke chamber ionization source. test mode since the internal op amps and comparators are power strobed, adjustments for sensitivity or low battery level could be difficult and/or timeconsuming. by forcing pin 12 to v ss , the power strobing is bypassed and the output, pin 1, constantly shows smoke/no smoke. pin 1 = v dd for smoke. in this mode and during the 10 ms power strobe, chip current rises to approximately 50 m a. led pulse the 9volt battery level is checked every 40 seconds dur- ing the led pulse. the battery is loaded via a 10 ma pulse for 11.6 ms. if the led is not used, it should be replaced with an equivalent resistor such that the battery loading remains at 10 ma. hysteresis when smoke is detected, the resistor/divider network that sets sensitivity is altered to increase sensitivity. this yields approximately 100 mv of hysteresis and reduces false triggering. figure 5. typical application as ionization smoke detector to other units mc145018 116 2 3 4 5 6 7 8 15 14 13 12 11 10 9 330 w 8.2 m w + 9 v 0.1 m f 1.5 m w * 0.001 m f 220 k w * 0.1 m f 1 m 1 m test *note: component values may change depending on type of piezoelectric horn used. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
465 motorola sensor device data www.motorola.com/semiconductors figure 6. mc145018 timing diagram osc pin 12 smoke n y low bat y n hyst pin 13 horn on off led off on 234567 9 8 no smoke, low battery 1 no smk no low bat low battery chirp osc pin 12 smoke n y no smk 23 24 1 6 12 18 24 smoke latch alarm condition ( 100 mv level shift) nfpa mod low bat y n horn on off led off on (note 1) 24 clocks 24 clocks notes: 1. horn modulation is selfcompleting. when going from smoke to no smoke, the alarm condition will terminate only when horn is o ff. 2. comparators are strobed once per cycle (1.65 sec for no smoke, 40 msec for smoke). 3. for timing under remote conditions, refer to mc14468 data sheet. figure 7. horn modulation nfpa72: temporal horn modulation pattern traditional 4/6 horn modulation pattern 0.5 sec 0.5 sec 0.5 sec 0.5 sec 0.5 sec 1.5 sec 167 msec 83 msec f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
466 motorola sensor device data www.motorola.com/semiconductors prepared by: leticia gomez and diana pelletier sensor applications engineering motorola semiconductor products sector phoenix, arizona introduction the mc14600, an ic designed for alarm applications, is a versatile part that can easily be configured with a minimum number of external components to serve a wide range of alarm applications and circuit configurations. for example, the mc14600 can be used in systems that detect pressure and temperature change, liquid levels, motion or intrusion. this application note presents considerations in interfacing exter- nal components to the mc14600 and an approach for config- uring it with a latch. the mc14600 alarm ic can be simply described as a comparator that determines whether an alarm condition exists and in response drives a piezo horn. as illustrated in figure 1 the mc14600 is more than a comparator and a horn driver. it drives an led to indicate the device is working and has inter- nal low battery detection circuitry. in the event of a low battery the mc14600 provides the signal to chirp the piezo horn. it also has a logical output that can be used to drive other out- puts such as an led. the mc14600 alarm threshold and oscillator speed are set externally providing system design flexibility. figure 2 is a detailed block diagram of the mc14600 that includes the pin numbers referenced in this document. figure 1. alarm ic concept input + alarm threshold low battery detection logical output piezo horn led figure 2. mc14600 block diagram 11 10 8 horn feedback horn out 2 horn out 1 alarm logic osc and timing 5 led v dd = pin 6 v ss = pin 9 7 v dd + low battery comparator v dd low v comp. out 4 v dd 3 low v set 1 detect comparator out + 13 detect comparator alarm threshold 15 alarm detect input + v dd hiz 16 guard amp 12 cosc rbias
semiconductor application note rev 3 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
467 motorola sensor device data www.motorola.com/semiconductors alarm threshold adjustments the alarm trigger point (alarm threshold) is set externally to any voltage level with a simple voltage divider connected to pin 13. for instance, to connect the alarm ic to a sensor that has an output of 1.0 v during a no alarm condition and 4.0 v during an alarm condition, the alarm threshold voltage could be set to 3.0 v using a 2 m w and a 1 m w resistor connected between v dd and ground (see figure 3). pin 13 connects internally to the negative input of the detect comparator. based on the input impedance of the detect comparator the maximum suggested total resistance for the threshold voltage divider is 10 m w . figure 3. alarm threshold voltage divider v dd 2 m 1 m pin 13 oscillator the master clock frequency for the mc14600 is determined by the external components rbias (pin 7) and cosc (pin 12). this rc network provides the timing for the various functions conducted by the ic. the oscillator timing affects the period between led pulses, alarm signal sampling, and the horn out- put pulses and power consumption. a standard rc network for the mc14600 oscillator uses an 8.2 m resistor (rbias) con- nected from v dd to pin 7 and a 0.1 uf capacitor (cosc) con- nected from pin 12 to ground. this configuration will provide a period of approximately 1.65 sec in standby and 41.67 msec in alarm. a change in oscillator speed is accomplished by changing the resistor and capacitor values previously stated. changing the oscillator timing will not change the horn pattern but it will change the speed at which it's delivered. the table below lists examples of rc values and measured sampling periods achieved with those values (deviation from theoretical values are due to tolerance in components). table 1. oscillator period vs. r bias and c osc value r bias c osc period (no alarm) period (alarm) 5.6 m w 0.01 m f 93 msec 2.3 msec 8.2 m w 0.01 m f 142 msec 3.4 msec 10 m w 0.01 m f 172 msec 3.9 msec 5.6 m w 0.1 m f 1.4 sec 32 msec 8.2 m w 0.1 m f 2.2 sec 50 msec 10 m w 0.1 m f 2.7 sec 60 msec 8.2 m w 1.0 m f 20.1 sec 456 msec piezo horn interface the mc14600 contains onboard horn driver circuitry to drive three leaded piezo horns. a three leaded horn is consid- ered selfdriven, having a feedback pin that is connected to a closed loop oscillation circuit. the mc14600 uses pin 8 (horn feedback), pin 10 (horn out 1) and pin 11 (horn out 2) to interface to a piezo horn and achieve the drive circuit. pin 10 and pin 11 alternate their output providing the oscillation for the horn. three external components are required to interface a piezo horn to the alarm ic: r1 , c1 and r2 (figure 4). r1 is usually around 1.5 m w and is the least critical component as it only biases the horn. r2 and c1 are critical to achieve maxi- mum horn output. the two components must be set so that the value of 1/(r2*c1) is close to the resonant frequency of the horn being used. table 2 lists a common horn frequency and potential external components that can be used for r2 and c1. figure 4. piezo horn interface to mc14600 fdbk 8 r2 r1 c1 11 out 2 alarm logic 10 out 1 table 2. external components for a 3.4 khz three leaded piezo horn horn osc. frequency r1 r2 c1 1/(r2*c1) 3.4 0.4 khz 1.5 m w 820 k w 1.5 m w 1.5 m w 200 k w 200 k w 120 k w 100 k w 1.5 nf 1.5 nf 2.2 nf 2.2 nf 3.33 khz 3.33 khz 3.79 khz 4.55 khz low battery threshold adjustments the alarm ic has a typical internal low battery reference voltage of 6 v. an internal resistor divider string provides a volt- age of 80% of v dd which is compared to the 6 v reference volt- age (see figure 5). this results in a low battery condition and horn chirp if the v dd level is decreased to approximately 7.5 v. the percentage of v dd that is compared can be changed by adding a resistor to pin 3. a resistor from pin 3 to v dd will lower the percentage while a resistor from pin 3 to gnd will increase the percentage. the low battery comparator information will be latched only during the led pulse. testing of the voltage at pin 3 should be done during the led pulse for confirmation. it should also be measured through a high impedance buffer to avoid altering the voltage level. alarm latching approaches there are detection applications where the event that trig- gers the alarm can be instantaneous, such as shock or motion. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
468 motorola sensor device data www.motorola.com/semiconductors figure 5. low battery detection circuitry + v dd low v comp. out 4 v dd 3 low v set osc and timing in this case the alarm ic would alarm for the brief moment that the event occurred and then stop. this is not always desirable, in particular during events where safety is of concern. a latch can be implemented using the concept of hystere- sis to alter the alarm threshold level and therefore remain in an alarm condition. it is very simple as it requires only one resistor, r3, connected to pin 1 (detect comp. out.) and added in series to the alarm threshold voltage divider, r1 and r2, on pin 13 (see figure 6). during a no alarm condition pin 1 is high which makes the alarm threshold voltage divider look like it would without r3 connected, keeping the alarm thresh- old at the initial desired point. when an alarm condition occurs pin 1 goes low, which in turn dramatically lowers the threshold voltage into the alarm comparator. when the alarm signal ends and the input voltage into pin 15 decreases, the alarm condition does not end because the alarm threshold has been lowered to below a standby voltage level. the mc14600 will continue in an alarm condition until the unit is reset or pin 15 receives a signal below this alarming threshold. a reset is implemented by connecting a switch to pin 1 that will toggle to v dd through a resistor. this solution has the possibility that it will not latch on to the alarm condition indefinitely. as described above it is essentially just lowering the alarm threshold voltage so if the output from the sensor during a no alarm condition is below this threshold the latch will not work. sample detection inputs the mc14600 is a versatile device because its high imped- ence input pin allows it to be connected to a variety of systems and input signals. all that is required for an input is a device figure 6. latch using resistor in series with threshold divider + alarm detect input (pin 15) alarm threshold r2 r1 13 1 detect comp. out r3 v dd internal to mc14600 100 w v dd reset switch or circuit that will produce a change in voltage that corre- sponds to an environmental change. for example, a simple circuit around a thermistor could cause the mc14600 to alarm when the temperature gets too high. a phototransistor could be connected to cause an alarm for either the absence or exis- tence of light. motorola also has sensors, specifically accelerometers and pressure sensors, that could be used as the input to the mc14600. an accelerometer, such as motorola's mma1201p, could be used to sense a shock or vibration. a possible solution is shown in figure 7. the mc7805 is a volt- age regulator that provides the 5 v supply required by the mma1201p. since the output of the mma1201p resulting from a shock or vibration is very short some simple peak detection circuitry is required to keep the signal high long enough for the mc14600 to latch onto the alarm condition. figure 7. shock and vibration detection circuit output to pin 15 (alarm detect input) 10 m 1.0 m f d1 mma1201p 7805 5 v f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
469 motorola sensor device data www.motorola.com/semiconductors motorola's pressure sensors can also provide the input to the mc14600. the mpx5000 series includes a wide variety of compensated and integrated pressure sensors with different pressure ranges, packaging and measurement options. one possible sensor is the mpxv5010. the output of the mpxv5010 can be fed directly into the input of the mc14600 (pin 15). if the latch described above is used with a pressure sensor resistors may be required at the output of the mpxv5010 to scale the output voltage (see figure 8). this is because the output voltage for pressure sensors in the mpx5000 series under no pressure is 0.2 v, which may be be- low the lowered alarm threshold. (see previous section.) figure 8. pressure detection circuit v dd output to pin 15 (alarm detect input) mpxv5010 conclusion the mc14600 offers a simple solution for use in a wide vari- ety of alarm applications. with a high impedance input pin it can be connected to many types of sensor devices. for sen- sor inputs that require a latched alarm condition there are sev- eral simple ways to add this option to the mc14600. it has the feature of not having a predetermined alarm threshold which gives it the flexibility of being set to any level as required by the application. the mc14600 has an internal horn driver that can drive a three leaded piezo horn with the addition of two resis- tors and one capacitor. the mc14600 integrates the features desired in alarm devices into a small and simple package that is still flexible enough for all types of alarm applications. f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
470 motorola sensor device data www.motorola.com/semiconductors
prepared by: rudi lenzen application engineer, toulouse france introduction the mc14600 is an integrated circuit (ic) designed for lowcost applications requiring an alarm to be triggered and heard. this device affords the designer a lowcost, easytointegrate solution, where board space and design time are at a premium. the alarm ic can be used in multiple applications, such as personal, home and auto safety/security devices; door, gate and pool alarms; and even toys, where lasers and motion are employed, for example. however, this paper's purpose is to introduce you to just a few applications for which the mc14600 is a perfect fit. gas sensor application the mc14600, used with a flammable gas sensor and a few added components, provides a reliable solution for gas detection. when gas leakage is detected, the sensing resistor decreases typically by a factor 3 or 4 as the gas concentration reaches 10 percent of the lower explosive limit. during the calibration sequence (test under gas), a variable resistor is used to set the trigger level of the alarm ic comparator which, in response, drives a piezo horn. by adding a thermistorewith negative temperature coefficient (ntc) in this caseein the detection circuit, the variation of the sensor resistance with temperature is easily compensated, avoiding false alarms when the room temperature increases. + r v supply r sensor calibration resistor p15 p13 th low battery detection alarm ic led piezohorn logical figure 1. gas detection example the logical output is useful to signal a remote control station that a gas leakage has been detected. when using a low power sensor, the circuit is fully compliant with a portable solution enhanced by the integrated low battery comparator indicating the state of the power supply. temperature level detector when connected to a simple network of thermistor and resistors, the alarm ic provides a portable solution for temperature control and supervision. the example hereafter uses an ntc thermistor. an audible alarm will sound when the threshold value at the comparator input is reached. a logic output is usable for starting either a fan or a heater depending upon the required temperature. figure 2. temperature level example + r v supply p15 p13 th low battery detection alarm ic led piezohorn logical semiconductor technical data rev 0 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
471 motorola sensor device data www.motorola.com/semiconductors water level detector a single probe connected directly on the detection pin of the alarm ic provides a portable solution for water level detection. when liquid enters in contact with the probe, the resistor between the detection pin and the supply drops from an open circuit to a measurable value. with an appropriate choice of bridge resistors, the presence of liquid will trigger the comparator. the logic level can be connected to any monitoring system allowing pump starting, floodgate closing and others. this simple system is useful for numerous applications, such as swimming pool water level alarms, defrosting water level detectors, and inhouse flood alarms. + v supply probe p15 p13 low battery detection alarm ic led piezohorn logical figure 3. waterlevel detection example motion indicator the alarm ic can be used to detect motion and can be integrated into products, such as an ordinary clothes iron, where this is critical. used with a low g accelerometer and a few logic components, the device can signal the user that there is a risk of clothes burning during use and that the iron must be shut off from the ac power after use. at the output of the accelerometer, a simple peak detection circuit is required to keep the signal active long enough. when no movement is detected, the output comparator is low and the counter starts. a first abeepo is heard after a few seconds to advise that there is a risk of clothes burning. if no movement is detected, the counting continues and drives a flipflop connected to pin 15 of the alarm ic. the alarm is triggered and will continue on until a new movement is detected, resetting the counter. + v supply low g accelerometer p15 low battery detection alarm ic led piezohorn logical figure 4. motion indicator example logic block counter gates flipflop + including filter monitor an ideal solution for air cleanliness control is provided when the alarm ic is directly connected to an mpx5000 series pressure sensor. this sensor family is compensated in temperature and has its output signal directly exploitable (internally amplified). therefore, the sensor can be connected to the detection pin of the circuit without any additional component. when a certain level of dust affects the efficiency of the filter, a differential pressure is measured and the alarm ic comparator is triggered. + v supply mpx5xxx series p15 p13 low battery detection alarm ic led piezohorn logical figure 5. pressure change (filter) example f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
472 motorola sensor device data www.motorola.com/semiconductors package outline dimensions case 64808 issue r case 751g04 issue d notes: 1. dimensioning and tolerancing per ansi y14.5m, 1982. 2. controlling dimension: inch. 3. dimension l to center of leads when formed parallel. 4. dimension b does not include mold flash. 5. rounded corners optional. style 1: pin 1. cathode 2. cathode 3. cathode 4. cathode 5. cathode 6. cathode 7. cathode 8. cathode 9. anode 10. anode 11. anode 12. anode 13. anode 14. anode 15. anode 16. anode style 2: pin 1. common drain 2. common drain 3. common drain 4. common drain 5. common drain 6. common drain 7. common drain 8. common drain 9. gate 10. source 11. gate 12. source 13. gate 14. source 15. gate 16. source a b f c s h g d j l m 16 pl seating 18 9 16 k plane t m a m 0.25 (0.010) t dim min max min max millimeters inches a 0.740 0.770 18.80 19.55 b 0.250 0.270 6.35 6.85 c 0.145 0.175 3.69 4.44 d 0.015 0.021 0.39 0.53 f 0.040 0.70 1.02 1.77 g 0.100 bsc 2.54 bsc h 0.050 bsc 1.27 bsc j 0.008 0.015 0.21 0.38 k 0.110 0.130 2.80 3.30 l 0.295 0.305 7.50 7.74 m 0 10 0 10 s 0.020 0.040 0.51 1.01 notes: 1. dimensions are in millimeters. 2. dimensioning and tolerancing per asme y14.5m, 1994. 3. datums a and b to be determined at the plane where the bottom of the leads exit the plastic body. 4. this dimension does not include mold flash, protrusion or gate burrs. mold flash, protrusion or gate burrs shall not exceed 0.15mm per side. this dimension is determined at the plane where the bottom of the leads exit the plastic body. 5. this dimension does not include interlead flash or protrusions. interlead flash and protrusions shall not exceed 0.25mm per side. this dimension is determined at the plane where the bottom of the leads exit the plastic body. 6. this dimension does not include dambar protrusion. allowable dambar protrusion shall not cause the lead width to exceed 0.62mm. 89 1 16 seating plane 7 0.75 x45 8x m 0.25 b 0.49 16x b m 0.25 a t 4 10.55 10.05 10.45 10.15 a 7.6 7.4 b pin 1 index pin's number 5 a a 0.25 1.0 0.4 0 0.32 0.23 section aa 0.35 2.65 2.35 0.25 0.10 6 t 16x 0.1 t 1.27 14x f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
51 motorola sensor device data www.motorola.com/semiconductors

section five alphanumeric device index 52 . . . . . . . . . . . . . . . . . f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
52 motorola sensor device data www.motorola.com/semiconductors alphanumeric device index

f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
53 motorola sensor device data www.motorola.com/semiconductors

f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
54 motorola sensor device data www.motorola.com/semiconductors f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .
how to reach us: usa/europe/locations not listed: motorola literature distribution p.o. box 5405, denver, colorado 80217 1-800-441-2447 or 480-768-2130 japan: motorola japan ltd. sps, technical information center 3-20-1, minami-azabu minato-ku tokyo 106-8573, japan 81-3-3440-3569 asia/pacific: motorola semiconductors h.k. ltd. silicon harbour centre 2 dai king street tai po industrial estate tai po, n.t. hong kong 852-26668334 home page: http://motorola.com/semiconductors dl200/d, rev 5 information in this document is provided solely to enable system and software implementers to use motorola products. there are no express or implied copyright licenses granted hereunder to design or fabricate any integrated circuits or integrated circuits based on the information in this document. motorola reserves the right to make changes without further notice to any products herein. motorola makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does motorola assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation consequential or incidental damages. atypicalo parameters which may be provided in motorola data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. all operating parameters, including atypicalso must be validated for each customer application by customer's technical experts. motorola does not convey any license under its patent rights nor the rights of others. motorola products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body, or other applications intended to support or sustain life, or for any other application in which the failure of the motorola product could create a situation where personal injury or death may occur. should buyer purchase or use motorola products for any such unintended or unauthorized application, buyer shall indemnify and hold motorola and its officers, employees, subsidiaries, affiliates, and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized use, even if such claim alleges that motorola was negligent regarding the design or manufacture of the part. motorola and the stylized m logo are registered in the us patent and trademark office. all other product or service names are the property of their respective owners. ? motorola inc. 2003 f r e e s c a l e s e m i c o n d u c t o r , i freescale semiconductor, inc. f o r m o r e i n f o r m a t i o n o n t h i s p r o d u c t , g o t o : w w w . f r e e s c a l e . c o m n c . . .

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