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KMA36 universal magnetic encoder km a36 rev 4 www.meas - spec.com 201 2 - july 1 / 16 ? contactless absolute 360 (180) angle measurement ? incremental mode ? l inear mode ? standard i 2 c i nterface (100 khz) ? programmable r esolution up to 13 bit (0.04 degree) ? very low hysteresis ? high accuracy mode ? user programmable parameters ? low power mode ? sleep and automatic wake - up over i 2 c ? programmable zero position ? device address hardware configurable ? small pb - free package (tssop20 ) ? rohs complian t description the KMA36 is a universal magnetic encoder for precise rotational or linear measurement. these position sensors feature a system - on - chip technology that combines a magnetoresistive element along with analog to digital converter and signal processing in a standard small package. by using anisotropi c magneto resis - tive (amr) technology, the KMA36 is able to determine contactlessly the magnetic angle of an external magnet over 360, as well as the incremental position on a magnetic pole strip with 5 mm pole length. its sleep and low power mode as well as automatic wake - up over i2c C make the KMA36 ideal for many bat tery applications. position data can be transmitted using a pwm or two - wire (sda, scl) communication bus. using the programmable parameters, the user can have access to a wide range of configuration to ensure the maximum of freedom and functionalities. key - features resolution 13 bit / 0.04 degree operating power supply range of 3v to 5.5v 3.0 C 5.5v operating temperature - 25 - +85 c average current 10 C 30 m a sleep current 1.2 ma data update rate 24 C 720 hz i 2 c clockrate up to 100 kbit/s applications industrial environment harsh environment handling machine machine tools robotics potentiometer motor motion control
KMA36 universal magnetic encoder kmt 36 rev 4 www.meas - spec.com 201 2 - july 2 / 16 pin assignment figure 1 : pin assignment electrical character istics unless otherwise specified, all voltages are referenced to the power ground supply vss. typical values are based on top= 2 5 c, vcc = 5 v. they are given only as design guidelines and are not tested in production. data based on characterization results, design simulation and/or technology characteristics are indicated in the table footnotes and are not tested in production. absolute maximum ratings are limiting values of permitted operation and should never be exceeded under the worst possible conditions either initially or consequently. if exceeded by even the smallest amount, instantaneous catastrophic failure can occur. an d even if the device continues to operate satisfactorily, its life may be considerably shortened. figure 2 : functional block description pin no. KMA36 tssop symbol type description 1 a1 nc not connected 2 a0 i slave adress configuration pin 3 dvcc_se o drive pin to power sensor 4 sda i/o two-wire interface data pin 5 pwm o pwm output 6 scl i two-wire interface clock pin 7 gnd_se s sensor supply ground pin 8 vcc_se s sensor power supply pin 9 nc nc not connected 10 nc nc not connected 11 nc nc not connected 12 coilp i coil power supply pin 13 coiln i coil power supply pin 14 aref i asic analog reference 15 nc nc not connected 16 gnd_as s asic supply ground 17 nc nc not connected 18 vcc_as s asic power supply 19 dcoiln o drive pin to coil power supply 20 dcoilp o drive pin to coil power supply angle mr magnet magnetic field amplification adc 10 bit core error handling i2c sensor evaluation communication op amp pwm mode handling position parameter pwm
KMA36 universal magnetic encoder kmt 36 rev 4 www.meas - spec.com 201 2 - july 3 / 16 absolute maximum ratings caution: exceeding these values may destroy the product. symbol parameter condition mi n. typ. max. unit t op operating temperature - 25 + 85 c t sto storage temperature - 40 + 85 c v cc operating voltage 2.9 6 v v in input voltage on any pin except on a1 - 0.5 6.5 v v in input voltage on a1 - 0.5 13 v i in dc current through any i/ o pin 40 ma i in dc current through s pin 200 ma i in dc current through any c pin 60 ma table 1: absolute maximum ratings ? operating conditions symbol parameter cond ition min. typ. max. unit t op operating temperature - 25 + 85 c v cc oper ating voltage 3 5 .5 v v in input voltage on i/o pin - 0.3 5.3 v a ref external analog reference 2.0 1) v cc v r aref analog reference input resistance - 32 - k? table 2: operating conditions 1) apply 2.0v at aref for best results please refer to the typical application section to know which external components should be connected. ? ac/dc characteristics symbol parameter condition min. typ. max. unit i av g average current 1) except in sleep mode, v cc = 5v 10 30 ma i sleep sleep current v cc = 5v 1.2 ma v i l input low voltage v cc = 5v, i ol = 10 ma 0.6 v v i h in put high voltage v cc = 5v, i oh = 10 ma 3 v v ol output low voltage v cc = 5v, i ol = 10 ma 0. 6 v v oh output high voltage v cc = 5v, i oh = 10 ma 4.3 v table 3 : ac/dc characteristics 1) current measurement has been done with a standard circuit including a voltage divider on aref.
KMA36 universal magnetic encoder kmt 36 rev 4 www.meas - spec.com 201 2 - july 4 / 16 ? system parameters symbol parameter condition min. typ. max. u nit f data update rate 1) 2) 24 720 hz t start starting time 5 ms r resolution h 0 =25 ka/m 3 ) 13 bit ? l linearity error h 0 =25 ka/m 3 ) 0.3 1 ? h hysteresis error h 0 =25 ka/m 3 ) 0.1 0.25 v bwn brown - out reset voltage 2.7 v t bwn brown - o ut reset pulse width 2 s h y applied magnetic field 15 25 60 ka/m r coil internal coil resistance 75 100 150 pwm pwm output resolution 10 bit f pwm pwm frequency 7.8 khz table 4 : system parameters 1) maximum is measured in speed mode wit h minimum oversampling. minimum is measured with maximum oversampling. 2) when using the analog - output configuration then update rate i s fixed at 8 8hz 3 ) system parameters apply only for recommended measurement setup (please refer to the arrangement sect ion) system output the system has two possible hardware output configurations: two - wire interface or analog output. ? analog output the system has a pulse width modulation unit with 10 bit resolution which can be easily coupled with a first order low - pass filter 1) to generate an analog output between vss and vcc corresponding to 0 and 360. in this hardware configuration, all internal registers are loaded with initial values. no digital configuration is necessary, all av ailable configurations can be set by changing the hardware setup 2) of the KMA36. 1) please refer to the typical application section for further information. 2) please refer to the hardware configuration section for further information. ? i 2 c (digital out put) the KMA36 has an i 2 c interface unit (two - wire interface, standard i2c - bus specification defined by philips semiconductors) with an 8 - bit data bus which can be easily used to retrieve measurement and configuration information. (please refer to the two - wire interface section for details) update rate f data = 1 / (1. 4 msec x oversampling / const) spd bit const 0 1 1 2
KMA36 universal magnetic encoder kmt 36 rev 4 www.meas - spec.com 201 2 - july 5 / 16 two wire in interfac e ? physical interface parameters symbol parameter condition min. typ. max. unit b rt clockrate 10 50 100 kb it /s a l address length 7 bit a s addres s 1) 0x59 hex table 5: physical interface parameters 1) please refer to the hardware configuration section to determine how to configure other addresses. ? timing parameters symbol parameter condition min. typ. max. unit t su :sta start s etup t ime 4.7 s t hd :sta start h old t ime 4.0 s t su :sto stop setup time 4.0 s t high clock h igh t ime 4.0 50 s t low clock l ow t ime 4.7 s t r rise t ime 1 s t f fall t ime 0.3 s t su :dat data i nput setup time 0.25 s t hd:dat data input hold time 0.3 s t bu f b us f ree time 4.7 s table 6 : start, stop and data timing parameters figure 3 : timing definitions 2) 2) please refer to the standard i2c - bus specification defined by philips semiconductors for further information.
KMA36 universal magnetic encoder kmt 36 rev 4 www.meas - spec.com 201 2 - july 6 / 16 ? registers (overview) the KMA36 contains the following i/o registers : table 7 : registers of the KMA36 ? i 2 c bus the KMA36 is always operating as a pure slave. ? i 2 c reading data it is possible to read up to seven bytes as described in the following figure. no special pro tocol is used by the reading - data process. table 8 : read data ? i 2 c writing data (general) the KMA36 can be controlled using two internal registers. the configuration (kconf) is an 8 - bit register and the resolution (kres) is a 16 - bit register. to writ e the 16 - bit register (kres) through the two - wire interface with an 8 - bit data bus, it is necessary to send the high byte first and then the low byte. in order to change the kma configuration , four bytes should be sent through the two - wire 8 - bit data bus. the first three bytes correspond to the configuration and resolution registers. the last byte contains a 8 - bit cyclic redundancy check (crc) value which can be calculated as described in the example. register size read/write function kconf 8 bit r/w configuration bits kres 16 bit w resolution ma 16 bit r magnetic angle ilc 32 bit r incremental counter registers of the KMA36 twi - read data byte 0 1 2 3 4 5 6 ma0 ma1 ilc0 ilc1 ilc2 ilc3 kconf read/write r r r r r r r initial value 0x00 0x00 0x00 0x00 0x00 0x00 0x03 byte 0:1 - ma1:0: magnetic angle unsigned integer giving the magnetic angle in degree with the configured resolution byte 2:5 - ilc3:0: incremental linear counter signed long giving the incremental linear counter in degree with the configured resolution. byte 6 - kconf: configuration register unsigned char giving the configuration register value.
KMA36 universal magnetic encoder kmt 36 rev 4 www.meas - spec.com 201 2 - july 7 / 16 table 9 : send data table 10 : crc ex ample twi - send data byte 0 1 2 3 kconf kresh kresl kcrc read/write w w w w initial value - - - - byte 0: kconf: configuration register contains the desired system configuration. byte 1:2 - kres: resolution register contains the desired resolution. byte 3 - kcrc: crc contains the cyclic redundancy check. example kconf kresh kresl kcrc data 0x03 0x7f 0xff 0x7f kcrc = 0xff - (kconf + kresh + kresl) + 0x01 kcrc = 0xff - (0x03 + 0x7f + 0xff) + 0x01 = 0x7f
KMA36 universal magnetic encoder kmt 36 rev 4 www.meas - spec.com 201 2 - july 8 / 16 ? kconf (configuration register) the configuration register is used to control and monitor the status and modes of the system: table 11 : kconf C configuration register the system has three possible main configurations: ? rota tional measurement used to measure the angle of a rotating magnet disc centered above the magnetic sensor center of the KMA36. 1) ? l inear measurement used to measure the linear movement of the KMA36 along a magnetic pole strip with 5mm pole l ength . a lookup table is used for internal error correction 1) ? sleep mode used to power down the KMA36. wake up is initiated by i 2 c communication 1) please refer to the arrangement section. ? cnt - bit ( kconf register) in addition, there is a n inc remental counter implemented, which can be enabled by writing a one to the cnt - bit in the kconf register. kconf - configuration register bit 7 6 5 4 3 2 1 0 slp - lin cnt pwr spd ovcs1 ovsc0 read/write w r/w r/w r/w r/w r/w r/w r/w initial value 0 0 0 0 0 0 1 0 bit 7 - slp: sleep mode writing this bit to one enables the sleep mode. this bit will be always set to zero by hardware. bit 5 - lin: mode writing this bit to one disables the rotational mode and enables the linear mode. bit 4 - cnt: mode writing this bit to one enables the incremental counter mode. by writing it to zero, the counter mode is turned off. bit 3 - pwr: low power mode writing this bit to one enables the low power mode. bit 2 - spd: speed mode writing this bit to one enables the fast speed mode. bit 1:0 - ovcs1:0: oversampling these bits determines the accuracy of the angle evaluation.
KMA36 universal magnetic encoder kmt 36 rev 4 www.meas - spec.com 201 2 - july 9 / 16 ? spd - bit ( kconf register) the measurement update rate can be increased by activating the fast mode with spd bit . in fast mode measurement accuracy is reduced. table 12 : update rate ? pwr - bit ( kconf register) t he power current consumption can be reduced with the low power mode accessible through the pwr bit. in low power mode only 180 measurement are possible. ? ovcs - bits ( kconf register) to increase the measurement accuracy, it is possible to configure the oversampling rate by using the ovscx bits. please notice that a higher accuracy leads to a reduction of the update rate ( please refer to the update rate table) table 13 : ovsc - oversampling ? kres ( resolution register) the resolution can be set to any decimal value between 1 and 32768. any other value would lead to unexpected system behavior. table 14 : kres - resolution register for example, a re solution of decimal 360 (0x00168) leads to rotational data in steps of 1 degree. a resolution of decimal 3600 (0x 0e10 ) results in steps of 0.1. update rate f data = 1 / (1. 4 msec x oversampling / const) spd bit const 0 1 1 2 ovcs1 ovsc0 oversampling 0 0 2 0 1 4 1 0 8 1 1 32 kres - resolution register bit 15 14 13 12 11 10 9 8 kresh kres15 kres14 kres13 kres12 kres11 kres10 kres9 kres8 kresl kres7 kres6 kres5 kres4 kres3 kres2 kres1 kres0 bit 7 6 5 4 3 2 1 0 read/write w w w w w w w w w w w w w w w w initial value 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
KMA36 universal magnetic encoder kmt 36 rev 4 www.meas - spec.com 201 2 - july 10 / 16 ha rdware configuration the hardware configuration depends on the desired output: two - wire interface or a nalog. in two - wire interface configuration, the slave address of the system can be configured by connecting a0 and another pin as described in following table. table 15 : twi / i 2 c slave address configuration in analog mode, the rotation direction can be configured by connecting dvcc_se and a power supply pin. the user zero reference angle calibration can be activated by connecting a0 and coilp. when the user zero reference angle calibration is active, the next evaluated magnetic angle will be set as the new zero reference angle. the user selectable output voltage for the zero reference angle can be configured by connecting a0 in series with a 4,7k ohm resistor and a port pin. the percentage i nd i cated is relative to the power supply value vcc and is defined at the zero reference angle position. table 1 6 : analog - mode configuration twi - slave address configuration address 0x59 a0 gnd 0x5a a0 dcoilp 0x5b a0 dcoiln 0x5c a0 dvcc_se 0x5d a0 vcc connection analog - rotation direction configuration direction cw dvcc_se vcc ccw dvcc_se 4,7k to gnd analog - user selectable output for zero reference percent 0% a0 4,7k to vcc 10% a0 4,7k to dvcc_se 25% a0 4,7k to dcoiln 50% a0 4,7k to gnd analog - zero reference angle user calibration status active a0 coilp inactive a0 - connection connection connection
KMA36 universal magnetic encoder kmt 36 rev 4 www.meas - spec.com 201 2 - july 11 / 16 typical application ? electrical circuit figure 4: typical circuit with two - wire interface fi gure 5: typical circuit with analog interface
KMA36 universal magnetic encoder kmt 36 rev 4 www.meas - spec.com 201 2 - july 1 2 / 16 arrangement due to the magneto resistive technology which senses the magnetic field in the sensor plane, it is advised to mount the magnet disc centered above the sensor center. please refer t o the magnets and scales section for more information about the magnetic center position of the KMA36. the magnetic scale should be placed perpendicularly to the KMA36 as depicted in the following figure rather in the middle along the width of the scale. f or best results the KMA36 should be as close as possible to the magnet. ? rotational (r ecommended ) setup (for best results) rotational mode bit lin = 0 pay attention to the magnetic center of the KMA36 ? linear setup linear mode bit lin =1 use mag netic pole strip with 5mm pole length for best results figure 6: mounting
KMA36 universal magnetic encoder kmt 36 rev 4 www.meas - spec.com 201 2 - july 13 / 16 magnets and scales rotational mode the KMA36 can be used with a magnet , preferably of disc or square shape or a magnet scale with pole pitch 5mm . for development purposes, meas offers a magnet disc made of plastic bonded nd - fe - b magnetic material which provides an homogenous magnetic field with sufficient magnetic field strength for typical application with the KMA36. the following table describes t ypical magnets parameters . please refer to the website http://www.magnetfabrik.de ( article number 67.044 - 1 ) and its application note section for more information. table 17a : typical meas disc - magnet specification linear mode the linear mode of the kma 3 6 is designed for a magnetic scale with pole pitch 5mm. a magnetic scale is made of a magnetic ferrite tape bonded on a steel support which guarantees mechanical stability. the steel support is made of an optimum stainless steel alloy that provides no los s of magnetic field strength. meas offers a standard scale with the following parameters for development purpose: table 17b : typical meas magnet - scale specification the correct magnet dimensions and assembly geometry depend on the specific arrangement of the application and are part of the specification of the entire system. symbol parameter condition min. typ. max. unit ? diameter neofer 48/60p only 14 mm t thickness neofer 48/60p only 2.5 mm b r magnetic field strength neofer 48/60p only 540 mt t op operating temperature neofer 48/60p only 150 c symbol parameter condition min. typ. max. unit l t length meas magnetic scale only 1 m l p pole length meas magnetic scale only 5 mm w width meas magnetic scale only 10 mm t thickness meas magnetic scale only 1.3 mm p accuracy meas magnetic scale only 40 m/m t op operating temperature meas magnetic scale only -40 100 c
KMA36 universal magnetic encoder kmt 36 rev 4 www.meas - spec.com 201 2 - july 14 / 16 package drawing figure 7 : package drawing (magnetic center) figure 8 : package drawing
KMA36 universal magnetic encoder kmt 36 rev 4 www.meas - spec.com 201 2 - july 15 / 16 common dimensions (millimeters) symbol min. typ. max. a - - 1.20 a1 0.05 - 0.15 a2 0.80 1.00 1.05 b 0.19 - 0.30 d 6.40 6.50 6.60 e - 6.40 - e1 4.30 4.40 4.50 e - 0.65 - l 0.45 0.60 0.75 n - 20 - r 0.09 - - s 0.20 - - table 18 : common dimensions
KMA36 universal magnetic encoder kmt 36 rev 4 www.meas - spec.com 201 2 - july 16 / 16 ordering code product description article number KMA36 KMA36 tsso p20 g - mrmo - 031 table 19 : ordering codes this data sheet contains data from the preliminary specification. supplementary data will be pu blished later . measurement specialties reserves the right to change the specification without notice, in order to impr ove the design and performance of the product. ordering information north america europe asia measurement specialties, inc. 1000 lucas way hampton, va 23666 united states phone: +1 - 800 - 745 - 8008 fax: +1 - 757 - 766 - 4297 email: sales@meas - spec.com web: www.meas - spec.com meas deutschland gmbh hauert 13 d - 44227 dortmund germany phone: +49 - (0)231 - 9740 - 0 fax: +49 - (0)231 - 9740 - 20 email: i nfo.de@meas - spec.com web: www.meas - spec.com measurement specialties china ltd. no. 26, langshan road high - tech park (north) nanshan district, shenzhen 518 057 china phone: +86 - 755 - 33305088 fax: +86 - 755 - 33305099 email: info.cn@meas - spec.com web: www.meas - spec.com the information in this sheet 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 such devices any license under the patent rig hts to the manufacturer. measurement specialties, inc. reserves the right to m ake changes without further notice to any product herein. measurement specialties, inc. makes no warranty, representation or guarantee regarding the suitability of its product for any particular purpose, nor does measurement specialties, inc. assume any li ability 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. typical param eters can and do vary in different applications. all op erating parameters must be validated for each customer application by customers technical experts. measurement specialties, inc. does not convey any license under its patent rights nor the rights of others.

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