Ch8-Protected-Low-Side-Drivers

BridgingTheoryinPracticeTransferringTechnicalKnowledgetoPracticalApplicationsProtectedLowSideDriversProtectedLowSideDriversProtectedLowSideDriversIntendedAudience:•Electricalengineerswithaknowledgeofsimpleelectricalcircuits•AnunderstandingofMOSFETsandlowsidedriversisassumedTopicsCovered:•WhatisaProtectedLowSideDriver?•WhattypeofprotectiondoesaHITFThave?•WhattypeofdiagnosticsdoesaHITFEThave?•HowdoesaHITFETimpactsystemEMI?•HowisaHITFETcircuitimplemented?•HITFETSelectionQuestionsExpectedTime:•Approximately90MinutesProtectedLowSideDrivers•IntroductiontoProtectedLowSideDrivers•HITFETProtectionFeatures•HITFETDiagnosticFeatures•EMI/EMCConsiderations•SystemImplementation•FrequentlyAskedQuestionsProtectedLowSideDrivers•IntroductiontoProtectedLowSideDrivers•HITFETProtectionFeatures•HITFETDiagnosticFeatures•EMI/EMCConsiderations•SystemImplementation•FrequentlyAskedQuestionsDSGN-ChannelMOSFET(Enhancement)MOSFETMetalOxideSemiconductorFieldEffectTransistorDSGN-ChannelMOSFET(Enhancement)DSGP-ChannelMOSFET(Enhancement)VGSVGSn+p+n+p+n+n-GateSourceSourceDrainP-ChannelMOSFET(Enhancement)GDSGSDMOSFETReviewMOSFETRegionsofOperation•Apositive(forN-Channel)ornegative(forP-Channel)VGSproducesaconductingchannelbetweentheDrainandSource•TheMOSFETisthenabletooperateintworegions:–1)Linearregion:TheMOSFETbehaveslikearesistance.–2)Saturationregion:TheMOSFETbehaveslikeacurrentsource.VGS0VN-ChannelMOSFET(NMOS)IDSVDSVGSincreasesVDS=VGS-VTLowSideDrive(LSD)Configuration14VLoadMOSFETSwitchTheswitchisonthe“low”sideoftheloadToturnon,theMOSFETgateispulledhighVgate@5Vto10VVgs=Vg-VsVgs=5Vto10VDrainvoltageissmall–ex.0.1voltDrainGateSourceVs=0VHITFET=HighIntegrationTemperatureprotectedFETHITFETMOSFETCurrentLimitOverTemperatureProtectionOverVoltageProtectionDiagnosticsRequiresexternalcomponentsShortCircuitProtectionHighIntegrationTemperatureprotectedFETCurrentLimitationdv/dtLimitationESDProtectionProtectionLoadVsupplyDrainSourceHITFETInputTabconnectionSHUNTOvervoltageOverVoltageProtectionOverTemperatureProtectionProtectedLowSideDrivers•IntroductiontoProtectedLowSideDrivers•HITFETProtectionFeatures•HITFETDiagnosticFeatures•EMI/EMCConsiderations•SystemImplementation•FrequentlyAskedQuestionsRuggedvs.ProtectedRugged•MOSFETs•Achievedthroughprocess&manufacturingtechnology•ProtectionNotBuiltinProtected•HITFETs•Achievedthroughdesignandutilizationofmoreadvancedintegratedcircuittechnologies•AvailableCMOS,DMOSandBipolardevicesallowfortheintegrationofESDprotection,activeclamping,currentlimit,temperaturesensing,etc.•ProtectionBuiltin•ElectrostaticDischarge(ESD)Protection•LoadDumpTolerant•InductiveandOvervoltageOutputClampProtection•CurrentLimitProtection•ThermalShutdownProtectionHITFETProtectionFeaturesBlockDiagramIncludingProtectionFeaturesCurrentLimitationdv/dtLimitationESDProtectionProtectionLoadVsupplyDrainSourceHITFETInputSHUNTOvervoltageOverVoltageProtectionOverTemperatureProtectionESDProtectionINSourceESDstructureESDstructures(Zener)arenotdesignedtoconductcontinuousDCcurrentElectrostaticdischargevoltage(HumanBodyModel)VESD2KVMaximumRatingsatTj=25ºC,UnlessOtherwiseSpecifiedLoadDumpProtectionDrive(Vin)Param*VoltageVpVbattVsPulseparamPulseTypeLoaddumpprotectionVin=loworhigh(8V)Vld804713.5Vloaddump=Vp+VsExponential+DCoffset*Vld=VoltageloaddumpInductiveAndOverVoltageClampInductiveandOverVoltageOutputClampOvervoltageconditionusuallyoccursinthepresenceofaninductiveswitchingactionThermalShutdownProtectionUpperthermalhysteresislimitLowerthermalhysteresislimitTimeJunctionTemperatureLoadCurrentInputVoltageVinABCDEFCurrentLimitProtectionIDTimeParamaterandConditionsatTj=25,Vbb=12VunlessotherwisespecifiedSymbolValuesUnitmintypmaxCurrentLimitVin=10V,Vds=12VIDlim11.51.9AThermalShutdownLatchBehaviorOvervoltageProtectionESDLatchShortcircuitprotectionCurrentLimitationOvertemperatureProtectiondv/dtlimitationDrainSourceInHITFET321VBBLoadThermalShutdownLatchBehaviorInputVinisdrivenhighInputcurrentreflectslatchcurrentconsumptionCurrentisswitchedoffwhenlatchengagesSilicontemperaturedropswhencurrentisswitchedoffProtectedLowSideDrivers•IntroductiontoProtectedLowSideDrivers•HITFETProtectionFeatures•HITFETDiagnosticFeatures•EMI/EMCConsiderations•SystemImplementation•FrequentlyAskedQuestionsHITFETDiagnosticFeedbackHITFETdoesnotcontaininternalstructuresthatArespecificallyintendedfordiagnosticfeedback•DiagnosticfeedbackcanbeobtainedbyusingexternalComponentsinconjunctionwith:–Drain–highcurrentoutputpin–trueconductivestateofdevicecanbeestimatedbymonitoringthedrainvoltage–Iin–inputdrivebiascanbedetectedandevaluatedagainstovercurrentorthermalshutdownbiascurrent–thismethodrequiresthatinputcurrentbeevaluated.NOTE:CaremustbetakensoasnottosignificantlyreducetheavailableVinvoltage•Drain–highcurrentoutputpin–trueconductivestateofdevicecanbeestimatedbymonitoringthedrainvoltage•Vin–inputdrivebiascanbedetectedandevaluatedagainstovercurrent,orthermalshutdownbiascurrent–thismethodrequiresthatinputcurrentbeevaluated.•NOTE:CaremustbetakensoasnottosignificantlyreducetheavailableVinvoltageDiagnosticfeed