Temperature Sensor Interface Module for …

1 400 300 200 100 01002003004005006007008009001000 Error (SC) Temperature (SC) C002 Measure ADC Error in SC Target specification for -200SC to +850SC TI DesignsTemperatureSensorInterfaceModulef or ProgrammableLogicControllers(PLC)SPACERT I DesignsTI Designsprovidethe foundationthat you needDesignFeaturesincludingmethodology,t estingand designfiles to Two DifferentSensorInputChannels:quicklyeval uateand customizethe Designs K-TypeThermocoupleInputwith CJChelpyouaccelerateyourtime to market. Compatibleto 2-, 3-, or 4-WireRTDP robesDesignResources RatiometricMeasurementfor RTD MeasurementAccuracyfor Thermocouple 1 CToolFolderContainingDesignFilesTIDA-000 18 ADS1220 ProductFolder MeasurementAccuracyfor RTD CLM5017 ProductFolder SensorOpenCircuit/SignalOut-of-RangeDete ctionLM5069 ProductFolder DigitalIsolationfor I/O ControllerInterfaceISO7141 CCProductFolder 24 V 20%InputPowerSupplyOperationISO1540 ProductFolder IEC-61000-4-4.

2 EFT Up to 1 KV at 5 KHz onTPS71533 ProductFolderSignalPortsTPS7A4901 ProductFolderTCA6408 AProductFolder IEC-61000-4-2:ESDUp to 4-KVContactand 8-KVLM94022 ProductFolderAir DischargeLMP275 ProductFolder IEC-61000-4-5:SurgeUp to 1-KVLine-EarthTS5A23159 ProductFolder(CM)on SignalPortsSPACERF eaturedApplications ProgrammableLogicControllers FactoryAutomationand ProcessControlASKOur AnalogExperts PortableInstrumentationWebBench CalculatorTools DataAcquisitionSystems IndustrialRoboticsMeasuredErrorof RTDI nputacrossTemperatureRangeof -200 C to 850 CAll trademarksare the propertyof May 2014 TemperatureSensorInterfaceModulefor ProgrammableLogicControllers(PLC)

3 SubmitDocumentationFeedbackCopyright 2014,TexasInstrumentsIncorporatedDesignS pecificationsand IMPORTANTNOTICEat the end of this TI referencedesignaddressesauthorizeduse, intellectualpropertymattersand otherimportantdisclaimersand FeaturesTable1 showsthe designspecificationsof theTemperatureSensorInterfaceModulefor ProgrammableLogicControllers(PLC) FEATURESI nputsTwo channelsK-Typesthermocouple2-, 3-, and 4-wirePT100 RTDprobesSensorTypes(HardwaresupportsRTD swith resistanceup to 2 k , whereasexistingTIVAMCU softwareisimplementedfor PT100 RTDonly)For thermocouplechannel: C; Overthe entireTC temperatureRange: 200 C toOverallMeasurementAccuracy1372 C(excludingsensorerrors)For RTDchannel: C.

4 Overthe entireRTDtemperatureRange: 200 C to 850 CFor CResolutionFor CColdJunctionCompensationOn-boardlocalte mperaturesensorIC(CJC)TypeColdJunctionCo mpensation0 C to 60 CTemperatureRangeMeasurementTypeRatiomet ricfor RTDPT100 RTD( 200 C to 850 C) and Thermocouple( 200 C to 1372 C) lookuptablesSensorLinearInterpolationimp lementedin TIVA MCUsoftwareModuleCalibrationADC s offsetand gain calibrationPowerSupplyRange18 V to 32-VDCI solation250-VDC (Continuous),Basicisolation1500-VAC for one minuteESDI mmunityIEC 61000-4-2:4 kV contactdischarges,8 kV air dischargesEFT ImmunityIEC 61000-4-4: 1 kV at 5 kHz on signalportsSurgeTransientImmunityIEC 61000-4-5.

5 1 kV line-earth(CM)on signalportsOperatingTemperatureRange0 C to 60 CStorageTemperature 40 C to 85 CTemperature,SurroundingAir60 C50-pinconnectorpluggabletoPLCI/O ModuleFront-EndControllerUsinga Tiva C SeriesARM Cortex -M4 MCU(TIDU191)Connector(s)4-pinscrewtermin alblockfor 2-, 3-, and 4-wireRTDprobes2-pindedicatedK-typetherm ocoupleconnectorFormFactor(L x W) x (Smallindustrialformfactor)2 TemperatureSensorInterfaceModulefor ProgrammableLogicControllersTIDU271 May 2014(PLC)SubmitDocumentationFeedbackCopy right 2014, sole objectiveof this referencedesignis to focuson the completecircuitdesignguidelinesthat helpengineersand systemarchitectsto develophigh precisiontemperaturemeasurementsolutions using24-bit delta-sigmaADCand mostwidelyusedtemperaturesensorslike thermocouplesand ResistanceTemperatureDetectors(RTDs).

6 This referencedesignaddressessensorsignalcond itioning,thermocouplecold junctioncompensation,ratiometricmeasurem enttechniquefor RTDs,recommendedsoftwareflow,sensorlinea rization,sensordiagnostics,transientprot ection,PCBlayout,and otherpracticaldesignconsiderationsfor achievinghigh-precisionrobustdesignfor TemperatureSensorInterfaceModuleis a fully isolateddesignwhichis essentialfor signalchainand powerline galvanicisolationbarrierbetweenthe host controllerside and the measurementside havebeenachievedusingdigitalisolatorsand a flybacktransformer, heartof this referencedesignis the ADS1220device,a 24-bitdelta-sigmaADC,whichprovidesa high resolution,high integration,low noise.

7 And low cost completesensoranalogfront-endforDC designis also suitableto interfacewith differenttypesof boardspace,reducesdesignefforts,reducest ime to market,and demonstratesotherTI products,suchas hot swapand in-rushcurrentlimitcontroller,isolatedFl y-Buck controller,low noiseLDO,digitalisolators,localtemperatu resensors,analogswitchand I2C to GPIO expanderthat can be usedin the ,externalprotectioncircuitryis circuitryhas beensuccessfullytestedand verifiedfor compliancewith regulatoryIEC61000-4standards:EFT,ESD,an d standardIEC61000-4is necessaryto ensurethat the designnot only survivesbutalso performsas intendedin harshor the relevantdesignfiles like Schematics,BOM,LayerPlots,AltiumFiles,Ge rber,and TIVA C-SeriesMCUsoftwareare executablewith an easy-to-useGraphicalUserInterface(GUI).

8 Usersmay downloadthe files at BlockDiagramof TemperatureSensorInterfaceModulefor PLC3 TIDU271 May 2014 TemperatureSensorInterfaceModulefor ProgrammableLogicControllers(PLC)SubmitD ocumentationFeedbackCopyright 2014, TemperatureSensorInterfaceModuleprovides two differentialinputchannelsto take measurementsfromtwo channelsupports2-, 3-, and designusesa singleADS122024-bitdelta-sigmaADCwithan externalTS5A23159dual channel2 x 1 multiplexerswitchesthe twodifferentialanaloginputsto sharethe host controllercommunicateswith TCA6408A- I2 Cto the GPIO expanderoveran I2C bus.

9 Crossingthe isolationbarriervia the routeone of the two inputsto the inputchannelselectionis donein signalcomingin or goingout of the moduleis protectedagainsthigh voltagefast transientevents,whichare oftenexpectedin protectioncircuitrymakesuse of TVSand temperaturesensors(especiallythermocoupl es)produceoutputin the millivoltrange,whichmakessensorsproneto RC low-passdifferentialand commonmodefiltersare usedon eachanaloginputbeforeit reachesthe filterseffectivelyeliminatesany high frequencynoisepickupwhichmay be designprovidestwo localtemperaturesensorICs to sensethe cold junction(or referencejunction)

10 A multi-gainanalogoutputtype temperaturesensorfed to ADS1220afterpassingthrougha low passfilter and one additionalTS5A23159dual channel2 x 1 is the TMP275,whichis a two-wiredigitaloutputtemperaturesensordi rectlyinterfacedto the I2C datareadysignal(DRDY)fromADS1220reportst he conversionstatus,whichconnectsto the GPIOpin of TCA6408A,configuredas convertedsensordata,the host controllerpollsfor the datareadystatuslatchedinsidethe inputport registerof TCA6408 Aoverthe I2C ProgrammableLogicControllersTIDU271 May 2014(PLC)