 |
|
| If you can't view the Datasheet, Please click here to try to view without PDF Reader . |
|
|
|
| If you can't view the Datasheet, Please click here to try to view without PDF Reader . |
|
|
| Datasheet File OCR Text: |
| www.sensirion.com version0.91Coctober2010 1/12 preliminary datasheet SHT25 humidityandtemperaturesensor fullycalibratedwith1.8%rhaccuracy digitaloutput,i 2 cinterface lowpowerconsumption excellentlongtermstability dfntypepackageCreflowsolderable dimensions figure 1: drawingofSHT25sensorpackage,dimensionsare given in mm (1mm = 0.039inch), tolerances are 0.1m m. the die pad (center pad) is internally connected to vss . the nc pads must be left floating. vss = gnd, sda = data. numberingofe/opadsstartsatlowerrightcorner (indicatedby notchindiepad)andgoesclockwise(comparetable 2). sensor chip SHT25 features a generation 4c cmosens? chip. besides the capacitive relative humidity sensor and the band gap temperature sensor, the chip contains an amplifier, a/d converter, otp memory and a digital processingunit. material contents while the sensor itself is made of silicon the sens ors housing consists of a plated cu leadframe and gree n epoxybased mold compound. the device is fully rohs andweeecompliant,e.g.freeofpb,cdandhg. additional information and evaluation kits additional information such as application notes is available from the web page www.sensirion.com/SHT25 . for more information please contact sensirion via info@sensirion.com . for SHT25 two evaluation kits are available: ekh4, a fourchanneldevicewithviewersoftware,thatalso serves for datalogging, and a simple ekh5 directly conne cting onesensorviausbporttoacomputer. 1.0 1.0 2 . 4 0 . 3 0.4 1.5 0.4 0.75 1.1 0.2 scl sda nc nc vss vdd bottomview SHT25 d0ac4 3.0 2.2 0.8typ 1.4 typ 3.0 0.3typ 2.0typ product summary SHT25, the new humidity and temperature sensor of sensirion is about to set new standards in terms of size and intelligence: embedded in a reflow solderable d ual flat no leads (dfn) package of 3 x 3mm foot print a nd 1.1mm height it provides calibrated, linearized sig nals in digital,truei 2 cformat. with a completely new designed cmosens? chip, a reworked capacitive type humidity sensor and an improvedbandgaptemperaturesensortheperformanc e hasbeenliftedevenbeyondtheoutstandinglevelo fthe previous sensor generation (sht1x and sht7x). for example, measures have been taken to stabilize the behaviorathighhumiditylevels. every sensor is individually calibrated and tested. lot identification is printed on the sensor and an elec tronic identification code is stored on the chip C which c an be read out by command. furthermore, the resolution of SHT25 can be cha nged by command (8/12bit up to 12/14bit for rh/t), low battery can be detected and a checksumhelpstoimprovecommunicationreliability . with made improvements and the miniaturization of t he sensortheperformanceto priceratiohasbeenimproved C and e ventually, any device should benefit from the cutting edge energy saving operation mode. for testing SHT25anewevaluationkitekh4isavailable.
www.sensirion.com version0.91Coctober2010 2/12 sensor performance relative humidity 1234 parameter condition min typ max units 12bit 0.04 %rh resolution 1 8bit 0.7 %rh typ 1.8 %rh accuracy tolerance 2 max seefigure2 %rh repeatability 0.1 %rh hysteresis 1 %rh nonlinearity <0.1 %rh responsetime 3 t 63% 8 s operatingrange extended 4 0 100 %rh longtermdrift 5 normal <0.5 %rh/yr 0 2 4 6 8 10 0 10 20 30 40 50 60 70 80 90 100 relative humidity (%rh) d dd d rh (%rh) maximaltolerance typicaltolerance figure 2 typical and maximal tolerance at 25c for relative humidity.forextensiveinformationseeusersguide ,sect.1.2. electrical specification parameter conditions min typ max units supplyvoltage,vdd 2.1 3.0 3.6 v sleepmode 0.15 0.4 a supplycurrent,idd 6 measuring 200 300 330 a sleepmode 0.5 1.2 w measuring 0.6 0.9 1.0 mw powerdissipation 6 average8bit 3.2 w heater vdd=3.0v 5.5mw, d t=+0.51.5c communication digital2wireinterface,truei 2 cprotocol table 1 electrical specification. for absolute maximum valuesseesection4.1ofusersguide. 1 defaultmeasurementresolutionis14bit(temperatur e)/12bit(humidity).itcan bereducedto12/8bit,11/11bitor13/10bitbycomm andtouserregister. 2 accuracies are tested at outgoing quality control a t 25c (77f) and 3.0v. values exclude hysteresis and long term drift and a re applicable to non condensingenvironmentsonly. 3 timeforachieving63%ofastepfunction,validat 25cand1m/sairflow. 4 normal operating range: 080%rh, beyond this limit sensor may read a reversibleoffsetwithslowkinetics(<3%rhafter2 00hoursat90%rh).formore detailspleaseseesection1.1oftheusersguide. temperature 567 parameter condition min typ max units 14bit 0.01 c resolution 1 12bit 0.04 c typ 0.2 c accuracy tolerance 2 max seefigure3 c repeatability 0.1 c 40 125 c operatingrange extended 4 40 257 f responsetime 7 t 63% 5 30 s longtermdrift <0.04 c/yr 0.0 0.5 1.0 1.5 2.0 2.5 3.0 40 20 0 20 40 60 80 100 120 temperature (c) d dd d t (c) maximaltolerance typicaltolerance figure 3 maximaltolerancefortemperaturesensorinc. packaging information sensortype packaging quantity ordernumber tape&reel 400 110076901 SHT25 tape&reel 1500 110076801 thisdatasheetissubjecttochangeandmaybeamen ded withoutpriornotice. 5 value may be higher in environments with vaporized solvents, outgassing tapes, adhesives, packaging materials, etc. for mor e details please refer to handlinginstructions. 6 min and max values of supply currentand power diss ipation arebased on fixed vdd = 3.0v and t<60c. the average value is b ased on one 8bit measurementpersecond. 7 responsetimedependsonheatconductivityofsenso rsubstrate. www.sensirion.com version0.91Coctober2010 3/12 users guide SHT25ss 1 extended specification for details on how sensirion is specifying and test ing accuracy performance please consult application not e statementonsensorspecification. 1.1 operating range the sensor works stable within recommended normal rangeCseefigure4.longtermexposuretoconditi ons outside normal range, especially at humidity >80%rh , maytemporarilyoffsettherhsignal(+3%rhafter6 0h). after return into the normal range it will slowly r eturn towards calibration state by itself. see section 2. 3 reconditioning procedure for eliminating the offs et. prolongedexposuretoextremeconditionsmayaccele rate ageing. figure 4 operatingconditions 1.2 rh accuracy at various temperatures maximaltoleranceforrhaccuracyat25cisdefine din figure 2. for other temperatures maximal tolerance has beenevaluatedtobewithinlimitsdisplayedinfig ure5. 100 5 5 5 5 5 4 5 5 5 5 5 5 5 5 6 8 10 5 5 5 4 4 3 4 4 4 4 4 4 4 5 5 6 8 90 5 5 4 3 2 2 2 3 3 3 3 4 4 4 5 6 8 5 4 4 3 2 2 2 3 3 3 3 4 4 4 5 6 8 80 4 4 4 3 2 2 2 3 3 3 3 3 3 4 4 5 6 4 4 4 3 2 2 2 3 3 3 3 3 3 3 4 5 6 70 4 4 4 3 2 2 2 3 3 3 3 3 3 3 4 5 6 4 4 3 3 2 2 2 2 3 3 3 3 3 3 4 5 6 60 4 3 3 2 2 2 2 2 2 2 2 2 2 3 3 4 5 4 2 2 2 2 2 2 2 2 2 2 2 2 3 3 4 5 50 4 2 2 2 2 2 2 2 2 2 2 2 2 3 3 4 5 4 2 2 2 2 2 2 2 2 2 2 2 2 3 3 4 4 40 4 2 2 2 2 2 2 2 2 2 2 2 2 3 3 4 4 4 3 3 2 2 2 2 2 2 2 2 2 2 3 3 4 4 30 4 3 3 2 2 2 2 2 2 2 2 2 2 3 3 4 4 4 4 3 2 2 2 2 2 2 2 2 2 2 3 3 4 4 20 4 4 4 3 2 2 2 3 3 3 3 3 3 3 3 4 4 5 4 4 3 2 2 2 3 3 3 3 3 4 4 4 4 5 10 8 5 5 4 3 2 3 4 4 4 4 4 4 4 5 6 8 8 8 8 6 5 3 5 5 5 5 5 5 5 5 6 8 10 0 12 12 12 8 5 4 5 5 6 6 6 6 6 8 10 12 12 0 10 20 30 40 50 60 70 80 relative humidity (%) temperature (c) figure 5 maximaltoleranceofrelativehumiditymeasuremen ts givenin%rhfortemperatures0C80c . pleasenotethatabovevaluesaremaximaltolerance s(not including hysteresis) against a high precision refe rence suchasadewpointmirror. 1.3 electrical specification currentconsumptionasgivenintable1isdependen ton temperatureandsupplyvoltagevdd.forestimations on energyconsumptionofthesensorfigures6and7ma ybe consulted.pleasenotethatvaluesgiveninthesef igures areoftypicalnatureandthevarianceisconsidera ble. 0 1 2 3 4 5 6 7 8 0 20 40 60 80 100 120 temperature (c) supply current idd (a) figure 6 dependency of supply current (sleep mode) versus temperature at vdd = 3.0v. please note the variance of the displayeddatamayexceed25%. 6 8 10 12 14 16 18 20 2.1 2.3 2.5 2.7 2.9 3.1 3.3 3.5 supply voltage (vdd) supply current idd (na) figure 7 typical dependency of supply current (sleep mode) versussupplyvoltageat25c.pleasenotethevari anceofthe displayeddatamayexceed25%. 0 20 40 60 80 100 40 20 0 20 40 60 80 100 120 temperature (c) relative humidity (%) max. range normal range datasheetSHT25 www.sensirion.com version0.91Coctober2010 4/12 2 application information 2.1 soldering instructions the dfns die pad (centre pad) and perimeter i/o pads are fabricated from a planar copper leadframe by o ver molding leaving the die pad and i/o pads exposed fo r mechanical and electrical connection. both the i/o pads and die pad should be soldered to the pcb. in order to preventoxidationandoptimizesoldering,thebotto mside ofthesensorpadsisplatedwithni/pd/au. onthepcbthe i/olands 8 shouldbe0.2mmlongerthan thepackagei/opads.inwardcornersmayberounded to matchthei/opadshape.thei/olandwidthshould match thedfnpackagei/opadswidth1:1andthelandfor the die pad should match 1:1 with the dfn package C see figure8. the soldermask 9 design forthelandpatternpreferablyis of type nonsolder mask defined (nsmd) with solder maskopenings larger than metal pads. for nsmd pads , the solder mask opening should be about 120m to 150mlargerthanthepadsize,providinga60mto 75m design clearance between the copper pad and solder mask. roundedportions of package pads should have a matchingroundedsoldermaskopeningshapetominim ize theriskofsolderbridging.fortheactualpaddim ensions, each pad on the pcb should have its own solder mask opening with a web of solder mask between adjacent pads. figure 8 recommendedmetallandpatternforsht2x.values inmm.diepad(centrepad)andncpadsmaybeleft floatingor be connected to ground. the outer dotted line repre sents the outerdimensionofthedfnpackage. for solderpasteprinting alasercut,stainlesssteelstencil with electropolished trapezoidal walls and with 0. 125mm stencil thickness is recommended. for the i/o pads the stencilaperturesshouldbe0.1mmlongerthanpcbp ads andpositionedwith0.1mmoffsetawayfromthecent reof thepackage.thediepadapertureshouldcoverabou t70 C 90% of the pad area C say up to 1.4mm x 2.3mm 8 thelandpatternisunderstoodtobethemetallaye ronthepcb,ontowhich thedfnpadsaresolderedto. 9 the solder mask is understood to be the insulating layer on top of the pcb coveringtheconnectinglines. centered on the thermal land area. itcan also be s plit in twoopenings. due to the low mounted height of the dfn, no clean type3solderpaste 10 isrecommendedaswellasnitrogen purgeduringreflow. figure 9 solderingprofileaccordingtojedecstandard.t p <= 260candt p <40secforpbfreeassembly.t l <220candt l < 150sec.rampup/downspeedsshallbe<5c/sec. itisimportanttonotethatthedicededgeorside facesof thei/opadsmayoxidiseovertime,thereforeasol derfillet may or may not form. hence there is no guarantee fo r solderjointfilletheightsofanykind. forsolderingsht2x,standard reflowsoldering ovensmay be used. the sensor is qualified to withstand solde ring profile according to ipc/jedec jstd020d with peak temperatures at 260c during up to 40sec for pbfre e assemblyinir/convectionreflowovens(seefigure 9). for manual soldering contact time must be limited t o 5 secondsatupto350c 11 . important: after soldering, the devices should be stored at >75%rh for at least 12h to allow the sens or elementtorehydrate.otherwisethesensormayrea dan offset that slowly disappears if exposed to ambient conditions. alternatively the rehydration process may be performed at ambient conditions (>40%rh) during mor e than5days. in no case, neither after manual nor reflow solderi ng, a boardwashshallbeapplied.therefore,andasment ioned above,itisstronglyrecommendedtousenoclean solder paste.incaseofapplicationswithexposureofthe sensor tocorrosivegasesorcondensedwater(i.e.environ ments with high relative humidity) the soldering pads sha ll be sealed (e.g. conformal coating) to prevent looseco ntacts orshortcuts. 10 soldertypesarerelatedtothesolderparticlesiz einthepaste:type3covers thesizerangeof25C45m(powdertype42). 11 260c=500f,350c=662f temperature time t p t p t l t s (max) t l preheating criticalzone 1.0 1.0 0.3 0.4 1.5 0.4 0.7 5 0.2 0.2 2.4 2.3 1. 4 datasheetSHT25 www.sensirion.com version0.91Coctober2010 5/12 2.2 storage conditions and handling instructions moisture sensitivity level (msl) is 2, according to ipc/jedec jstd020d.1; hence storage time is limit ed tooneyearafterdateofdelivery. it is of great importance to understand that a humi dity sensorisnotanormalelectroniccomponentandnee dsto be handled with care. chemical vapors at high concentration in combination with long exposure tim es mayoffsetthesensorreading. forthisreasonitisrecommendedtostorethesens orsin original packaging including the sealed esd bag at followingconditions:temperatureshallbeinther angeof 10cC50candhumidityat20C60%rh(sensorstha t arenotstoredinesdbags).forsensorsthathave been removed from the original packaging we recommend to storetheminesdbagsmadeofmetalinpehd 12 . in manufacturing and transport the sensors shall be preventedofhighconcentrationofchemicalsolvent sand longexposuretimes.outgassingofglues,adhesive tapes and stickers or outgassing packaging material such as bubble foils, foams, etc. shall be avoided. manufac turing areashallbewellventilated. for more detailed information please consult the document handlinginstructions orcontactsensirion. 2.3 reconditioning procedure asstatedaboveextremeconditionsorexposuretos olvent vaporsmayoffsetthesensor.thefollowingrecondi tioning proceduremaybringthesensorbacktocalibration state: baking: 100C105cat<5%rhfor10h rehydration: 20C30cat~75%rhfor12h 13 . 2.4 temperature effects relative humidity reading strongly depends on temperature. therefore, it is essential to keep hum idity sensors at thesame temperature as the air of which the relative humidityisto be measured. in case of tes ting or qualification the reference sensor and test sensor must show equal temperature to allow for comparing humid ity readings. if the sensor shares a pcb with electronic componen ts that produce heat it should be mounted in a way tha t prevents heat transfer or keeps it as low as possib le. measures to reduce heat transfer can be ventilation , reduction of copper layers between the sensor and t he rest of the pcb or milling a slit into the pcb arou nd the sensorCseefigure10. 12 forexample,3mantistaticbag,product1910with zipper. 13 75%rh can conveniently be generated with saturated nacl solution. 100C105ccorrespondto212C221f,20C30cco rrespondto68C86f furthermore, there are selfheating effects in case the measurementfrequencyistoohigh.tokeepselfhea ting below 0.1c, sht2x should not be active for more th an 10% of the time C e.g. maximum two measurements per secondat12bitaccuracyshallbemade. figure 10 topviewofexampleofmountedsht2xwithslits milledintopcbtominimizeheattransfer. 2.5 light the sht2x is not light sensitive. prolonged direct exposuretosunshineorstronguvradiationmayage the sensor. 2.6 materials used for sealing / mounting many materials absorb humidity and will act as a bu ffer increasingresponsetimesandhysteresis.materials inthe vicinityof thesensor must therefore becarefully chosen. recommended materials are: any metals, lcp, pom (delrin),ptfe(teflon),peek,pp,pb,pps,psu,pv df, pvf. for sealing and gluing (use sparingly): use high fi lled epoxy for electronic packaging (e.g. glob top, unde rfill), and silicone. outgassing of these materials may al so contaminatethesensor(seesection2.2).therefore tryto add the sensor as a last manufacturing step to the assembly, store the assembly well ventilated after manufacturing or bake at >50c for 24h to outgas contaminantsbeforepacking. 2.7 wiring considerations and signal integrity carrying the scl and sda signal parallel and in clo se proximity(e.g.inwires)formorethan10cmmayre sultin cross talk and loss of communication. this may be resolved by routing vdd and/or vss between the two sda signals and/or using shielded cables. furthermo re, slowingdownsclfrequencywillpossiblyimprovesi gnal integrity. power supply pins (vdd, vss) must be decoupledwitha100nfcapacitorCseenextsection . datasheetSHT25 www.sensirion.com version0.91Coctober2010 6/12 3 interface specifications pin name comment 1 sda serialdata,bidirectional 2 vss ground 5 vdd supplyvoltage 6 scl serialclock,bidirectional 3,4 nc notconnected table 2 sht2x pin assignment, nc must remain floating (top view) 3.1 power pins (vdd, vss) thesupplyvoltageofsht2xmustbeintherangeof 2.1C 3.6v,recommendedsupplyvoltageis3.0v.powersup ply pins supply voltage (vdd) and ground (vss) must be decoupledwitha100nfcapacitor,thatshallbepla cedas closetothesensoraspossibleCseefigure11. 3.2 serial clock (scl) scl is used to synchronize the communication betwee n microcontroller(mcu)andthesensor.sincetheint erface consists of fully static logic there is no minimum scl frequency. 3.3 serial sda (sda) the sda pin is used to transfer data in and out of the sensor. for sending a command to the sensor, sda is valid on the rising edge of scl and must remain sta ble whilesclishigh.afterthefallingedgeofsclth esda valuemaybechanged.forsafecommunicationsdash all be valid t su and t hd before the risingand after the falling edge of scl, respectively C see figure 12. for read ing datafromthesensor,sdaisvalidt vd aftersclhasgone lowandremainsvaliduntilthenextfallingedgeo fscl. figure 11 typicalapplicationcircuit,includingpullupre sistors r p anddecouplingofvddandvssbyacapacitor. toavoidsignalcontentionthemicrocontrolleruni t(mcu) must only drive sda and scl low. external pullup resistors(e.g.10k),arerequiredtopullthesig nalhigh. for the choice of resistor size please take bus cap acity requirementsintoaccount(comparetable5).itsho uldbe notedthatpullupresistorsmaybeincludedini/o circuits of mcus. see table 4 and table 5 for detailed i/o characteristicofthesensor. 4 electrical characteristics 4.1 absolute maximum ratings the electrical characteristics of sht2x are defined in table1.theabsolutemaximumratingsasgivenint able 3 are stress ratings only and give additional infor mation. functional operation of the device at these conditi ons is not implied. exposure to absolute maximum rating conditions for extended periods may affect the sens or reliability(e.g.hotcarrierdegradation,oxidebr eakdown). parameter min max units vddtovss 0.3 5 v digitali/ opins(sda,scl) tovss 0.3 vdd+0.3 v inputcurrentonanypin 100 100 ma table 3 electricalabsolutemaximumratings esd immunity is qualified according to jedec jesd22 a114e method (human body model at 4kv), jedec jesd22a115a method (machine model 200v) and esda esdstm5.3.11999 and aecq100011 (charged device model, 750v corner pins, 500v other pins).latchupimmunityisprovidedataforcecur rentof 100mawitht amb =125caccordingtojedecjesd78. for exposure beyond named limits the sensor needs additionalprotectioncircuit. 4.2 input / output characteristics theelectricalcharacteristicssuchaspowerconsum ption, low and high level input and output voltages depend on the supply voltage. for proper communication with t he sensor it is essential to make sure that signal des ign is strictlywithinthelimitsgivenintable4&5and figure12. parameter conditions min typ max units outputlow voltage,vol vdd=3.0v, 4ma datasheetSHT25 www.sensirion.com version0.91Coctober2010 8/12 5.4 hold / no hold master mode there are two different operation modes tocommunic ate with the sensor: hold master mode or no hold master mode.inthefirstcasethescllineisblocked(co ntrolled bysensor)duringmeasurementprocesswhileinthe latter casethescllineremainsopenforothercommunicat ion whilethesensorisprocessingthemeasurement.no hold master mode allows for processing other i 2 c communication tasks on a bus while the sensor is measuring.acommunicationsequenceofthetwomode s isdisplayedinfigure15andfigure16,respective ly. inthe holdmastermode ,thesht2xpullsdownthescl linewhilemeasuringtoforcethemasterintoawai tstate. byreleasingthescllinethesensorindicatesthat internal processing is terminated and that transmission may be continued. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 s 1 0 0 0 0 0 0 0 ack 1 1 1 0 0 1 0 1 ack i 2 caddress+write command(seetable6) 19 20 21 22 23 24 25 26 27 s 1 0 0 0 0 0 0 1 ack measurement i 2 caddress+read holdduringmeasurement 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 0 1 1 0 0 0 1 1 ack 0 1 0 1 0 0 1 0 ack data(msb) data(lsb) stat. 46 47 48 49 50 51 52 53 54 0 1 1 0 0 0 1 1 nack p checksum figure 15 holdmaster communicationsequenceCgreyblocks are controlled by sht2x. bit 45 may be changed to n ack followedbystopcondition(p)toomitchecksumtra nsmission. in no hold master mode, the mcu has to poll for the terminationoftheinternalprocessingofthesenso r.thisis done by sending a start condition followed by the i 2 c header(10000001)asshowninfigure16.ifthein ternal processingisfinished,thesensoracknowledgesthe pollof the mcu and data can be read by the mcu. if the measurement processing is not finished the sensor answers no ack bit and the start condition must be issuedoncemore. for both modes, since the maximum resolution of a measurement is 14 bit, the two last least significa nt bits (lsbs, bits 43 and 44) are used for transmitting st atus information. bit 1 of the two lsbs indicates the measurementtype(0:temperature,1humidity). bit0is currentlynotassigned. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 s 1 0 0 0 0 0 0 0 ack 1 1 1 1 0 1 0 1 ack i 2 caddress+write command(seetable6) 19 20 21 22 23 24 25 26 27 measurement s 1 0 0 0 0 0 0 1 nack measuring i 2 caddress+read 19 20 21 22 23 24 25 26 27 measurement s 1 0 0 0 0 0 0 1 ack continuemeasuring i 2 caddress+read 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 0 1 1 0 0 0 1 1 ack 0 1 0 1 0 0 1 0 ack data(msb) data(lsb) stat. 46 47 48 49 50 51 52 53 54 0 1 1 0 0 0 1 1 nack p checksum figure 16 no hold master communication sequence C grey blocks are controlled by sht2x. if measurement is n ot completeduponreadcommand,sensordoesnotprov ideack on bit 27 (more of these iterations are possible). if bit 45 is changed to nack followed by stop condition (p) chec ksum transmissionisomitted. in the examples given in figure 15 and figure 16 th e sensor output is s rh = 0110001101010000. for the calculationofphysicalvaluesstatusbitsmustbe setto0 Cseechapter6. themaximumdurationformeasurementsdependsonth e typeofmeasurementandresolutionchosenCvalues are displayedintable7.maximumvaluesshallbechose nfor thecommunicationplanningofthemcu. resolution rhtyp rhmax ttyp tmax units 14bit 66 85 ms 13bit 33 43 ms 12bit 22 29 17 22 ms 11bit 12 15 9 11 ms 10bit 7 9 ms 8bit 3 4 ms table 7 measurement times for rh and t measurements at different resolutions. typical values are recommend ed for calculatingenergyconsumptionwhilemaximumvalues shallbe appliedforcalculatingwaitingtimesincommunicat ion. pleasenote:i 2 ccommunicationallowsforrepeatedstart conditions (s) without closing prior sequence with stop condition(p)Ccomparefigures15,16and18.stil l,any sequence with adjacent start condition may alternat ively beclosedwithastopcondition. datasheetSHT25 www.sensirion.com version0.91Coctober2010 9/12 5.5 soft reset this command (see table 6) is used for rebooting th e sensor system without switching the power off and o n again. upon reception of this command, the sensor system reinitializes and starts operation according to the defaultsettingsCwiththeexceptionoftheheater bitinthe userregister(seesect.5.6).thesoftresettakes lessthan 15ms. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 s 1 0 0 0 0 0 0 0 ack 1 1 1 1 1 1 1 0 ack p i 2 caddress+write softreset figure 17 softreset Cgreyblocksarecontrolledbysht2x. 5.6 user register the content of user register is described in table 8. please note that reserved bits must not be changed and default values of respective reserved bits may chan ge overtimewithoutpriornotice.therefore,forany writingto theuserregister,defaultvaluesofreservedbits mustbe read first. thereafter, the full user register stri ng is composed of respective default values of reserved b its andtheremainderofaccessiblebitsoptionallywit hdefault ornondefaultvalues. bit #bits description/coding default 7,0 2 measurementresolution rh t 00 12bit 14bit 01 8bit 12bit 10 10bit 13bit 11 11bit 11bit 00 6 1 status:endofbattery 15 0:vdd>2.25v 1:vdd<2.25v 0 3,4,5 3 reserved 2 1 enableonchipheater 0 1 1 disableotpreload 1 table 8 user register.cutoff valueforendof batterys ignal mayvaryby0.05v.reservedbitsmustnotbechang ed.otp reload = 0 loads default settings after each tim e a measurementcommandisissued. the end of battery alert is activated when the battery powerfallsbelow2.25v. the heater is intended to be used for functionality diagnosis C relative humidity drops upon rising temperature. the heater consumes about 5.5mw and providesatemperatureincreaseofabout0.5C1.5 c. otpreload isasafetyfeatureandloadstheentireotp settingstotheregister,withtheexceptionofthe heaterbit, 15 thisstatusbitisupdatedaftereachmeasurement before every measurement. this feature is disabled per defaultandisnotrecommendedforuse.pleaseuse soft resetinsteadCitcontainsotpreload. anexamplefori 2 ccommunicationreadingandwritingthe userregisterisgiveninfigure18. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 s 1 0 0 0 0 0 0 0 ack 1 1 1 0 0 1 1 1 ack i 2 caddress+write readregister 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 s 1 0 0 0 0 0 0 1 ack 0 0 0 0 0 0 1 0 nack i 2 caddress+read registercontent 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 s 1 0 0 0 0 0 0 0 ack 1 1 1 0 0 1 1 0 ack i 2 caddress+write writeregister 55 56 57 58 59 60 61 62 63 0 0 0 0 0 0 1 1 ack p registercontenttobewritten figure 18 readandwriteregistersequence Cgreyblocksare controlledbysht2x.inthisexample,theresolutio nissetto8bit /12bit. 5.7 crc checksum crc8 is a well known standard checksum concept. for implementation please refer to public sources such as wikipedia. 5.8 serial number SHT25 provides an electronic identification code. f or instructionsonhowtoreadtheidentificationcode please refer to the application note electronic identific ation code C to be downloaded from the web page www.sensirion.com/SHT25 . 6 conversion of signal output defaultresolutionissetto12bitrelativehumidi tyand14 bittemperaturereading.measureddataaretransfer redin twobytepackages,i.e.inframesof8bitlengthw herethe mostsignificantbit(msb)istransferredfirst(le ftaligned). each byte is followed by an acknowledge bit. the tw o statusbits,thelastbitsoflsb,mustbesetto 0before calculating physical values. in the example of figu re 15 andfigure16,thetransferred16bitrelativehumi ditydata is0110001101010000=25424. 6.1 relative humidity conversion with the relative humidity signal output s rh the relative humidity rh isobtainedbythefollowingformula(resultin %rh),nomatterwhichresolutionischosen: datasheetSHT25 www.sensirion.com version0.91Coctober2010 10/12 16 rh 2 s 125 6 rh + - = in the example given in figure 15 and figure 16 the relativehumidityresultstobe42.5%rh. the physical value rh given above corresponds to th e relative humidity above liquid water according to w orld meteorologicalorganization(wmo).forrelativehum idity above ice rh i the values need to be transformed from relative humidity above water rh w at temperature t . the equation is given in the following, compare also applicationnoteintroductiontohumidity: ? ?? ? ? ?? ? + ? ?? ? ? ?? ? + = t t t t rh rh i i w w w i exp exp units are %rh for relative humidity and c for temperature. the corresponding coefficients are def ined as follows: w = 17.62, w = 243.12c, i = 22.46, i = 272.62c. 6.2 temperature conversion the temperature t iscalculated by inserting temperature signaloutput s t intothefollowingformula(resultinc),no matterwhichresolutionischosen: 16 t 2 s 175.72 46.85 t + - = 7 environmental stability thesht2xsensorseriesweretestedaccordingtoae c q100 rev. g qualification test method. sensor specifications are tested to prevail under the aec q100 temperaturegrade2testconditionslistedintable 9 16 . environment standard results 17 htol 125c,1000hours within specifications tc 50c125c,1000cycles within specifications uhst 130c/85%rh/2.3bar,96h within specifications thb 85c/85%rh,1000h within specifications esdimmunity hbm 4kv,mm 200v,cdm 750v/500v(corner/otherpins) qualified latchup forcecurrentof100mawith t amb =125c qualified table 9: performed qualification test series. htol = high temperature operating lifetime, tc = temperature cy cles, uhst = unbiased highly accelerated stress test, thb = temperaturehumiditybiased.fordetailsonesdsee sect.4.1. 16 temperaturerangeis40to105c(aecq100tempera turegrade2). 17 accordingtoaccuracyandlongtermdriftspecifica tiongivenonpage2. sensorperformanceunderothertestconditionscann otbe guaranteed and is not part of the sensor specificat ions. especially, no guarantee can be given for sensor performance in the field or for customers specific application. if sensors are qualified for reliability and behavi or in extreme conditions, please make sure that they experience same conditions as the reference sensor. it should be taken into account that response times in assemblies may be longer, hence enough dwell time f or the measurement shall be granted. for detailed information please consult application note testin g guide. 8 packaging 8.1 packaging type sht2x sensors are provided in dfn packaging (in analogy with qfn packaging). dfn stands for dual fl at noleads. thesensorchipismountedtoaleadframemadeof cu and plated with ni/pd/au. chip and lead frame are o ver molded by green epoxybased mold compound. please notethatsidewallsofsensorsaredicedandhence lead frame at diced edge is not covered with respective protectivecoating.thetotalweightofthesensor is25mg. 8.2 filter cap and sockets forsht2xafiltercapsf2willbeprovided.itis designed forfastresponsetimesandcompactsize.pleasefi ndthe datasheetonsensirionswebpage. for testing of sht2x sensors sockets, such as from plastronics, part number 10lq50s13030 are recommended(seee.g. www.locknest.com ). 8.3 traceability information all sht2x are laser marked with an alphanumeric, fi ve digitcodeonthesensorCseefigure19. themarkingonthesensorconsistsoftwolineswit hfive digits each. the first line denotes the sensor type (SHT25). the first digit of the second line defines the outputmode(d=digital,sensibusandi 2 c,p=pwm,s= sdm).theseconddigitdefinesthemanufacturingye ar(0 =2010,1=2011,etc.).thelastthreedigitsrepr esentan alphanumerictrackingcode.thatcodecanbedecode dby sensirion only and allows for tracking on batch lev el through production, calibration and testing C and w ill be provideduponjustifiedrequest. datasheetSHT25 www.sensirion.com version0.91Coctober2010 11/12 figure 19 lasermarkingonSHT25.fordetailsseetext. reels are also labeled, as displayed in figure 20 a nd figure21,andgiveadditionaltraceabilityinforma tion. figure 20: firstlabelonreel:xx=sensortype(25forsht2 5), o=outputmode(0=digital),nn=chipversion,y =lastdigit ofyear,rrr=numberofsensorsonreeldividedby 10(200for 2000units),ttttt=traceabilitycode. figure 21: second label on reel: for device type and part ordernumber(seepackaginginformationonpage2), delivery date (also date code) is date of packaging of senso rs (dd = day, mm = month, yyyy = year), cccc = sensirion ord er number. 8.4 shipping package sht2x are provided in tape & reel shipment packagin g, sealedintoantistaticesdbags.standardpackaging sizes are400,1500and5000unitsperreel.forSHT25,e ach reel contains 440mm (55 pockets) header tape and 200mm(25pockets)trailertape. the drawing of the packaging tapes with sensor orientationisshowninfigure22.thereelsarepr ovidedin sealedantistaticbags. figure 22 sketch of packaging tape and sensor orientation. header tape is to the right and trailer tape to the left on this sketch. 9 compatibility to sht1x / 7x protocol sht2x sensors may be run by communicating with the sensirionspecificcommunicationprotocolusedfor sht1x andsht7x.incasesuchprotocolisappliedplease refer to the communication chapter of datasheet sht1x or sht7x. please note that reserved status bits of use r registermustnotbechanged. pleaseunderstandthatwiththesht1x/7xcommunicat ion protocolonlyfunctionsdescribedinrespectivedat asheets can be used with the exception of the otp reload function that is not set to default on sht2x. as an alternative to otp reload the soft reset may be use d. pleasenotethatevenifsht1x/7xprotocolisappli edthe timing values of table 5 and table 7 in this sht2x datasheetapply. for the calculation of physical values the followin g equationmustbeapplied: forrelativehumidity rh res rh 2 s 125 6 rh + - = andfortemperature t res t 2 s 175.72 46.85 t + - = res isthechosenrespectiveresolution,e.g.12(12bi t)for relativehumidityand14(14bit)fortemperature. 8.0 2.0 4.0 0.3 1.3 r0.3max r0.25 ?0.15min ?0.15min 3.3 0.25 3.3 1.75 5.5 12.0 SHT25 d0ac4 device type: 1-100ppp-nn description: humidity & temperature sensor shtxx part order no. 1-100ppp-nn or customer number date of delivery: dd.mm.yyyy order code: 46cccc / 0 lot no.: xxo-nn-yrrrttttt quantity: rrrr rohs: compliant lot no. datasheetSHT25 www.sensirion.com version0.91Coctober2010 12/12 revision history date version page(s) changes 11june2010 0.3 1C9 initialpreliminaryrelease 25october2010 0.91 1C12 publicrelease important notices warning, personal injury do not use this product as safety or emergency stop devices or in any other application where failure of the product could result in personal injury. do not use this product for applic ations other than its intended and authorized use. before instal ling, handling, using or servicing this product, please consult the data sheet and application notes. failure to comply with these ins tructions could result in death or serious injury. if the buyer shall purchase or use sensirion produc ts for any unintended or unauthorized application, buyer shall defend, indemnify and hold harmless sensirion and its officers, emplo yees, subsidiaries, affiliates and distributors against a ll claims, costs, damages and expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injur y or death associated withsuchunintendedorunauthorizeduse,evenifs ensirionshallbe allegedlynegligentwithrespecttothedesignort hemanufactureofthe product. esd precautions the inherent design of this component causes it to be sensitive to electrostaticdischarge(esd).topreventesdinduc eddamageand/or degradation, take customary and statutory esd preca utions when handlingthisproduct. seeapplicationnoteesd,latchupandemcformor einformation. warranty sensirionwarrantssolelytotheoriginalpurchaser ofthisproductfor a period of 12 months (one year) from the date of d elivery that this product shall be of the quality, material and workm anship defined in sensirions published specifications of the product . within such period, if proven to be defective, sensirion shall repair and/or replacethisproduct,insensirionsdiscretion,fr eeofchargetothe buyer,providedthat: notice in writing describing the defects shall be g iven to sensirionwithinfourteen(14)daysaftertheirapp earance; such defects shall be found, to sensirions reasona ble satisfaction, to have arisen from sensirions fault y design, material,orworkmanship; thedefectiveproductshallbereturnedtosensirio nsfactoryat thebuyersexpense;and thewarrantyperiodforanyrepairedorreplacedpr oductshallbe limitedtotheunexpiredportionoftheoriginalpe riod. this warranty does not apply to any equipment which has not been installed and used within the specifications recomm ended by sensirion for the intended and proper use of the eq uipment. except for the warranties expressly set forth herein,sensirionmakesnowarranties,eitherexpre ss or implied, with respect to the product. any and al l warranties, including without limitation, warrantie s of merchantability or fitness for a particular purpose,areexpresslyexcludedanddeclined. sensirion is only liable for defects of this produc t arising under the conditionsofoperationprovidedforinthedatash eetandproperuseof the goods. sensirion explicitly disclaims all warra nties, express or implied,foranyperiodduringwhichthegoodsare operatedorstored notinaccordancewiththetechnicalspecifications . sensiriondoesnotassumeanyliabilityarisingout ofanyapplication or use of any product or circuit and specifically d isclaims any and all liability, including without limitation consequenti al or incidental damages. all operating parameters, including withou t limitation recommended parameters, must be validated for each customers applications by customers technical experts. recom mended parameterscananddovaryindifferentapplication s. sensirionreservestheright,withoutfurthernotic e,(i)tochangethe productspecificationsand/ortheinformationinth isdocumentand(ii)to improvereliability,functionsanddesignofthisp roduct. copyright ?2010,bysensirion. cmosens ? isatrademarkofsensirion allrightsreserved headquarter and sales offices headquarter sensirionag phone: +41443064000 laubisruetistr.50 fax: +41443064030 ch8712staefazh info@sensirion.com switzerland http://www.sensirion.com/ sales office usa: sensirioninc. phone: +18054094900 2801townsgaterd.,suite204 fax: +18054350467 westlakevillage,ca91361 michael.karst@sensirion.com usa http://www.sensirion.com/ sales office japan: sensirionjapanco.ltd. phone: +81334444940 postalcode:1080074 fax: +81334444939 shinagawastationbldg.7f, info@sensirion.co.jp 4235,takanawa,minatoku http://www.sensirion.co.jp tokyo,japan sales office korea: sensirionkoreaco.ltd. phone: +82314409925~27 #1414,anyangconstructiontowerb/d, fax: +8231 4409927 11121,bisandong,anyangcity info@sensirion.co.kr gyeonggiprovince http://www.sensirion.co.kr southkorea sales office china: sensirionchinaco.ltd. phone: +8675582521501 room2411,maintower fax: +8675582521580 jinzhonghuanbusinessbuilding, info@sensirion.com.cn futiandistrict,shenzhen, www.sensirion.com.cn postalcode518048 prchina findyourlocalrepresentativeat: http://www.sensirion.com/reps |
Price & Availability of SHT25
 |
|
|
|
|
All Rights Reserved © IC-ON-LINE 2003 - 2022 |
| [Add Bookmark] [Contact Us] [Link exchange] [Privacy policy] |
|
Mirror Sites : [www.datasheet.hk]
[www.maxim4u.com] [www.ic-on-line.cn]
[www.ic-on-line.com] [www.ic-on-line.net]
[www.alldatasheet.com.cn]
[www.gdcy.com]
[www.gdcy.net] |