IEPE Vibration Sensor Interface Reference Design for …

1 25 V1-pole HPFV ariable Attn:-6 G% -24 VSHORTOPENADS127L01 REF6025 SPITHS4551TS3A5017 LMV751 VcomVcomVcomSPILMV751 VcomV_CMinput25 VProgram. Gain:+6 G% +18 dBMFB LPF3rd order,20 kHz BWfixed gain = 6 dB8 MHzWB filterData Rate256 k 32 kSensor Failure DetectVcom GeneratorProgram. Current2-20 mAIEPE sensorcable+ + Copyright 2017, Texas Instruments Incorporated1 TIDUD62 July 2017 SubmitDocumentationFeedbackCopyright 2017,TexasInstrumentsIncorporatedIEPEV ibrationSensorInterfaceReferenceDesignfo r PLCA nalogInputTI Designs:TIDA-01471 IEPEV ibrationSensorInterfaceReferenceDesignfo r PLCA nalogInputDescriptionIndustrialvibration sensingis a crucialprocessinconditionmonitoring,whic his necessaryfor integratedelectronicpiezoelectric(IEPE)s ensoris the mostcommonvibrationsensorusedin the TIDA-01471designis a full analogfrontend for the IEPE sensorinterfaceand demonstrateshow to achieveflexiblehigh-resolution,high-spee dconversionwith low-powerand E2E ExpertsFeatures Single-ChannelIEPES ensorAnalogInput 24-BitConversionResolution 20-kHzSignalBandwidth ProgrammableDataRate:265 kSPSto 32 kSPS AdjustableGain: 12 dB to 18 dB ProgrammableExcitationCurrent.

2 2 mA to 20 mA 10-VAC Input,250-k InputImpedance 40 C to 85 C OperatingTemperatureRange Diagnostics:Wire-Break,Short-CircuitDete ction,and Short-CircuitProtectionApplications PLC,DCSA nalog,and MixedInputModule AnalogSignalConditioner/Transmitter VibrationSwitch DataAcquisitionand July 2017 SubmitDocumentationFeedbackCopyright 2017,TexasInstrumentsIncorporatedIEPEV ibrationSensorInterfaceReferenceDesignfo r PLCA nalogInputAn IMPORTANTNOTICEat the end of this TI referencedesignaddressesauthorizeduse, intellectualpropertymattersand otherimportantdisclaimersand high-resolution,high-speed-specializedse nsorinterfacecircuitsusedin a rangeof industrialcontrolproducts,includinghigh- endmeasurementand dataacquisition(DAQ)

3 Systems,vibrationswitches,conditioners,a nd transmitters,as well as dedicatedanaloginputmodulesfor programmablelogiccontrollers(PLCs).The IEPE vibrationsensorinterfaceis anessentialpart of the conditionmonitoringplatformsofferedby top PLCand distributedcontrolsystems(DCSs) rangeof existingIEPE sensorinterfaceproductsextendfromsinglec hannelto 12 or morechannelsfor bandwidthrangesfrom1 kHZ up to 100 kHz with20 kHz as the samplingfrequencyrangesfrom25 kSPSup to100 kSPS,with a resolutionof 16 bits to 24 SystemSpecificationsThis designis intendedfor use with a 24-bitconversionat maximumsamplingspeedsreachingup to 256 KSPS establishesthis designat the leadingedgeof designtargetsan inputbandwidthof 20 kHZ and a programmablegainbetween 12 dB to 18 dB.

4 A programmableexcitationcurrentof 2 mA to 20 mA as well as aprogrammablesamplingspeeddownto 32 kSPSmeansthat this designcan accommodatedifferentsensorcabledistances and short-circuitdetectionensuresafe and reliableoperationof the powerconsumptionand designfootprinthavebeenconsideredto allowan affordablesystemthat can be adjustedfor a largernumberofchannelswith a lists the key Key SystemSpecificationsPARAMETERSPECIFICATI ONSN umberof channels1 Inputrange 10 VResolution24 bitsAccuracy Hz to 20 kHzSamplingrate256 kSPS,128 KSPS,64 kSPS,and 32 kSPSSNR100 dBGainProgrammable: 12 dB to 18 dBInputimpedance250 k Excitationcurrent0 mA to 20 mA (8 bits of resolution)Excitationvoltage23 V (minimum)

5 Operationtemperature 40 C to 85 CDiagnosticfeaturesWire-breakand shortcircuitFormfactor55 mm 75 mmVibrationSensorSignal ConditioningData July 2017 SubmitDocumentationFeedbackCopyright 2017,TexasInstrumentsIncorporatedIEPEV ibrationSensorInterfaceReferenceDesignfo r PLCA nalogInput2 SystemOverviewMachinefailureis very costlyin a way of mitigatingthe downtimeofmachinesis to rely on ,regularly-scheduledmaintenancecannot the time of this writing,the industryactivelytransitioningtowardpredi ctivemaintenance,whichis the processof predictinga machinefailurebeforeit kindof maintenanceis the act ofcontinuouslymonitoringmachinetemperatu re, Vibration ,and empiricalmodelscan be appliedto link theseconditionparametersto the healthstatusof a machine,thus effectivelyindicatingwhethera componentis due for processgreatlyoptimizesmaintenancecost and ,defectbearing,loosemachinefoot,defectiv egears,defectpumps,and defectmotorsaresomeof the faultsthat are detailsthe componentsincludedin the VibrationMonitoringSystemComponents1.

6 Vibrationsensor Severalsensortypesare availablefor integratedelectronicspiezoelectric(IEPE) sensoris the mainstreamsensorusedfor Signalconditioning A vibrationsensorrequirespowerand its outputrequireseitherattenuationoramplifi cation,as well as ,high-passfiltering,and conditioningthe signalto matchthe subsequentADCinputis also a of thesefunctionsare implementedbythe Dataacquisition This componentis typicallya high-speed,high-resolutiondataconverterw ith Analysisplatform The high-speeddatageneratedby the DAQblockmustbe analyzedor convertedto the frequencydomain,wherethe vibrationprofileis comparedto a standardhealthymachineprofileand failuremodesare designshowsthe implementationof the signalconditioningand the DAQpartsfor an V1-pole HPFV ariable Attn.

7 -6 G% -24 VSHORTOPENADS127L01 REF6025 SPITHS4551TS3A5017 LMV751 VcomVcomVcomSPILMV751 VcomV_CMinput25 VProgram. Gain:+6 G% +18 dBMFB LPF3rd order,20 kHz BWfixed gain = 6 dB8 MHzWB filterData Rate256 k 32 kSensor Failure DetectVcom GeneratorProgram. Current2-20 mAIEPE sensorcable+ + Copyright 2017, Texas Instruments July 2017 SubmitDocumentationFeedbackCopyright 2017,TexasInstrumentsIncorporatedIEPEV ibrationSensorInterfaceReferenceDesignfo r TIDA-01471 BlockDiagramThe IEPE sensorinterfaceof the TIDA-01471blockdiagramshowsthreemainsect ionsof the Design :thecurrentsource,the fault detectioncircuit,and the signalchain,whichis the signalchainiscomposedof a variableattenuator,a programmablegain stage,a differentiallow passfilter stage,andhigh-speedanalog-to-digitalconv erter(ADC).

8 The currentsourcepowersthe sensorand drawsits own powerfroma voltagesupplyhigherthan24 V toaccommodatefor the large inputsignalis AC coupled,amplified,or attenuatedusinga variablegain amplifierand thenlow-passfilteredbeforegoingto the samplingfrequencyabove50 kHz is requiredfor a typicalbandwidthequalto 20 designaimsfor 100 kSPSor moreat 24 bits of auxiliarycircuitfor detectingopen-or short-circuitconditionsis connectedtothe inputbeforethe detailsthe componentselectionand detaileddesignprocedureofthe LogicWideband 1 FilterLDO AINPAINNSCLKCSAVDDINTLDODOUTDINADS127L01 DRDY/FSYNCDGNDREFPREFN Wideband 2 FilterAGNDDVDD ADCM odulatorLow-Latency FilterSPI and Frame-Sync InterfaceDAISYIN FSMODEFORMATOSR [1:0]RESET/PWDNFILTER [1.]

9 0]CLKLVDDC opyright 2016, Texas Instruments July 2017 SubmitDocumentationFeedbackCopyright 2017,TexasInstrumentsIncorporatedIEPEV ibrationSensorInterfaceReferenceDesignfo r ADS127L01is a 24-bit,delta-sigma( ), analog-to-digitalconverter(ADC)with dataratesup to512 kSPS(seeFigure3). This deviceoffersa uniquecombinationof excellentDC accuracyandoutstandingAC high-order,chopper-stabilizedmodulatorac hievesvery-lowdrift withlow integrateddecimationfilter additiontoal low-latencyfilter,the ADS127L01providesmultiplewidebandfilters with less than of rippleand an optionfor 116-dBstop-bandattenuationat the ,industrial ADCsthat offergooddrift performanceuse digitalfilterswith a result,industrial ADCshavelimitedsignalbandwidthand are mostlysuitedfor audioapplicationsofferlargerusablebandwi dths,but the offsetand drift specificationsare ADS127L01combinestheseconverters.

10 Providinghigh-precisionindustrialmeasure mentwith excellentDC and AC specificationsoveran extendedindustrialtemperaturerangeof 40 C to +125 ADS127L01 BlockDiagramBandgapRFILTB uffer+ July 2017 SubmitDocumentationFeedbackCopyright 2017,TexasInstrumentsIncorporatedIEPEV ibrationSensorInterfaceReferenceDesignfo r REF60xxfamilyof voltagereferenceshavean integrated,low-outputimpedancebufferthat enablethe userto directlydrivethe REFpin of precisiondataconverterswhilepreservingli nearity,distortion,andnoiseperformance(s eeFigure4). MostprecisionSARand ADCsswitchbinary-weightedcapacitorsontot he REFpin duringthe REF6000familydevicesare well suitedto drivetheREFpin of the ADS127xxfamilyof REF60xxfamilyvariantspecifiesa maximumtemperaturedrift of just 5 ppm/ C and initialaccuracyof boththe voltagereferenceand the TS3A5017is a dual single-pole,quadruple-throw(4:1)analogsw itchthat is designedto V to V.