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ApplicationReportLM25183,LM25184,LM25183-Q1,andLM25184-Q1FunctionalSafetyFITRate,FMDandPinFMATableofContents1Overview.
22FunctionalSafetyFailureInTime(FIT)Rates.
33FailureModeDistribution(FMD)44PinFailureModeAnalysis(PinFMA)5TrademarksAllothertrademarksarethepropertyoftheirrespectiveowners.
www.
ti.
comTableofContentsSNVA990–AUGUST2020SubmitDocumentFeedbackLM25183,LM25184,LM25183-Q1,andLM25184-Q1FunctionalSafetyFITRate,FMDandPinFMA1Copyright2020TexasInstrumentsIncorporated1OverviewThisdocumentcontainsinformationforLM25183,LM25184,LM25183-Q1,andLM25184-Q1(WSONpackage)toaidinafunctionalsafetysystemdesign.
Informationprovidedare:FunctionalSafetyFailureInTime(FIT)ratesofthesemiconductorcomponentestimatedbytheapplicationofindustryreliabilitystandardsComponentfailuremodesandtheirdistribution(FMD)basedontheprimaryfunctionofthedevicePinfailuremodeanalysis(PinFMA)Figure1-1showsthedevicefunctionalblockdiagramforreference.
Figure1-1.
FunctionalBlockDiagramLM25183,LM25184,LM25183-Q1,andLM25184-Q1weredevelopedusingaquality-manageddevelopmentprocess,butwerenotdevelopedinaccordancewiththeIEC61508orISO26262standards.
Overviewwww.
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com2LM25183,LM25184,LM25183-Q1,andLM25184-Q1FunctionalSafetyFITRate,FMDandPinFMASNVA990–AUGUST2020SubmitDocumentFeedbackCopyright2020TexasInstrumentsIncorporated2FunctionalSafetyFailureInTime(FIT)RatesThissectionprovidesFunctionalSafetyFailureInTime(FIT)ratesforLM25183,LM25184,LM25183-Q1,andLM25184-Q1basedontwodifferentindustry-wideusedreliabilitystandards:Table2-1providesFITratesbasedonIECTR62380/ISO26262part11Table2-2providesFITratesbasedontheSiemensNormSN29500-2Table2-1.
ComponentFailureRatesperIECTR62380/ISO26262Part11FITIECTR62380/ISO26262FIT(FailuresPer109Hours)TotalComponentFITRate13DieFITRate7PackageFITRate6ThefailurerateandmissionprofileinformationinTable2-1comesfromtheReliabilitydatahandbookIECTR62380/ISO26262part11:MissionProfile:MotorControlfromTable11Powerdissipation:300mWClimatetype:World-wideTable8Packagefactor(lambda3):Table17bSubstrateMaterial:FR4EOSFITrateassumed:0FITTable2-2.
ComponentFailureRatesperSiemensNormSN29500-2TableCategoryReferenceFITRateReferenceVirtualTJ5CMOS,BICMOSDigital,analog/mixed25FIT55°CTheReferenceFITRateandReferenceVirtualTJ(junctiontemperature)inTable2-2comefromtheSiemensNormSN29500-2tables1through5.
FailureratesunderoperatingconditionsarecalculatedfromthereferencefailurerateandvirtualjunctiontemperatureusingconversioninformationinSN29500-2section4.
www.
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comFunctionalSafetyFailureInTime(FIT)RatesSNVA990–AUGUST2020SubmitDocumentFeedbackLM25183,LM25184,LM25183-Q1,andLM25184-Q1FunctionalSafetyFITRate,FMDandPinFMA3Copyright2020TexasInstrumentsIncorporated3FailureModeDistribution(FMD)ThefailuremodedistributionestimationforLM25183,LM25184,LM25183-Q1,andLM25184-Q1inTable3-1comesfromthecombinationofcommonfailuremodeslistedinstandardssuchasIEC61508andISO26262,theratioofsub-circuitfunctionsizeandcomplexityandfrombestengineeringjudgment.
Thefailuremodeslistedinthissectionreflectrandomfailureeventsanddonotincludefailuresduetomisuseoroverstress.
Table3-1.
DieFailureModesandDistributionDieFailureModesFailureModeDistribution(%)NoSWoutput45%SWoutputnotinspecification–voltageortiming40%SWpowerFETstuckon5%EN/UVLOfalsetriporfailstotrip5%Shortcircuittoanytwopins5%TheFMDinTable3-1excludesshortcircuitfaultsacrosstheisolationbarrier.
FaultsforshortcircuitacrosstheisolationbarriercanbeexcludedaccordingtoISO61800-5-2:2016ifthefollowingrequirementsarefulfilled:1.
ThesignalisolationcomponentisOVCIIIaccordingtoIEC61800-5-1.
IfaSELV/PELVpowersupplyisused,pollutiondegree2/OVCIIapplies.
AllrequirementsofIEC61800-5-1:2007,4.
3.
6apply.
2.
Measuresaretakentoensurethataninternalfailureofthesignalisolationcomponentcannotresultinexcessivetemperatureofitsinsulatingmaterial.
Creepageandclearancerequirementsshouldbeappliedaccordingtothespecificequipmentisolationstandardsofanapplication.
Careshouldbetakentomaintainthecreepageandclearancedistanceofaboarddesigntoensurethatthemountingpadsoftheisolatorontheprinted-circuitboarddonotreducethisdistance.
FailureModeDistribution(FMD)www.
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com4LM25183,LM25184,LM25183-Q1,andLM25184-Q1FunctionalSafetyFITRate,FMDandPinFMASNVA990–AUGUST2020SubmitDocumentFeedbackCopyright2020TexasInstrumentsIncorporated4PinFailureModeAnalysis(PinFMA)ThissectionprovidesaFailureModeAnalysis(FMA)forthepinsoftheLM25183,LM25184,LM25183-Q1,andLM25184-Q1.
Thefailuremodescoveredinthisdocumentincludethetypicalpin-by-pinfailurescenarios:Pinshort-circuitedtoGround(seeTable4-2)Pinopen-circuited(seeTable4-3)Pinshort-circuitedtoanadjacentpin(seeTable4-4)Pinshort-circuitedtosupply(seeTable4-5)Table4-2throughTable4-5alsoindicatehowthesepinconditionscanaffectthedeviceasperthefailureeffectsclassificationinTable4-1.
Table4-1.
TIClassificationofFailureEffectsClassFailureEffectsAPotentialdevicedamagethataffectsfunctionalityBNodevicedamage,butlossoffunctionalityCNodevicedamage,butperformancedegradationDNodevicedamage,noimpacttofunctionalityorperformanceFigure4-1showstheLM25183,LM25184,LM25183-Q1,andLM25184-Q1pindiagram.
ForadetaileddescriptionofthedevicepinspleaserefertothePinConfigurationandFunctionssectionintheLM25183,LM25184,LM25183-Q1,andLM25184-Q1datasheets.
Figure4-1.
PinDiagramTable4-2.
PinFMAforDevicePinsShort-CircuitedtoGroundPinNamePinNo.
DescriptionofPotentialFailureEffect(s)FailureEffectClassSW1VOUT=0V;DamagetotransformerAFB2VOUT=0V;DamageVINtoFBAVIN3VOUT=0VBEN/UVLO4VOUT=0V;ShutdownoperationBSS/BIAS5VOUT=0Vifshortduringstart-up.
VOUTnormalifshortduringsteady-stateBTC6Temperaturecompensationdisabled;VOUTtargetwillbeslightlydifferentduetoRtc||RsetCRSET7VOUT=ISW-PEAK*tOFF*Rload*NPS/240μs;120μsswitchingBGND8Normaloperation.
Dwww.
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comPinFailureModeAnalysis(PinFMA)SNVA990–AUGUST2020SubmitDocumentFeedbackLM25183,LM25184,LM25183-Q1,andLM25184-Q1FunctionalSafetyFITRate,FMDandPinFMA5Copyright2020TexasInstrumentsIncorporatedTable4-3.
PinFMAforDevicePinsOpen-CircuitedPinNamePinNo.
DescriptionofPotentialFailureEffect(s)FailureEffectClassSW1VOUT=0V;NoswitchingBFB2VOUT=0V;120μsswitchingBVIN3VOUT=0VBEN/UVLO4ShutdownorRegulatingsinceENishighimpedanceBSS/BIAS5VOUTregulating;InternalSSonlyCTC6VOUTregulating;TemperaturecompensationdisabledCRSET7VOUT=0V;VOUTcannotbesensedBGND8FloatingGNDBTable4-4.
PinFMAforDevicePinsShort-CircuitedtoAdjacentPinPinNamePinNo.
DescriptionofPotentialFailureEffect(s)FailureEffectClassSW1VOUT=0V;DamageVINtoFBdiodeAFB2VOUT=0V;VOUTcannotbesensedBVIN3VOUTregulating;AlwaysinACTIVEmodeCEN/UVLO4----SS/BIAS5CurrentlimitthresholdwillbelowerBTC6VOUT=ISW-PEAK*tOFF*Rload*NPS/240μsdependingonTC;VOUTcannotbesensedBRSET7VOUT=ISW-PEAK*tOFF*Rload*NPS/240μsdependingonTC;VOUTcannotbesensedBGND8--Table4-5.
PinFMAforDevicePinsShort-CircuitedtosupplyPinNamePinNo.
DescriptionofPotentialFailureEffect(s)FailureEffectClassSW1VOUT=0V;DamageSWtoGNDAFB2VOUT=0V;VOUTcannotbesensedBVIN3NormalOperationDEN/UVLO4VOUTregulating;AlwaysinACTIVEmodeCSS/BIAS5Damageto15VESDonSS/BIASATC6Damageto5VESDonTCARSET7Damageto5VESDonRSETAGND8VOUT=0VBPinFailureModeAnalysis(PinFMA)www.
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com6LM25183,LM25184,LM25183-Q1,andLM25184-Q1FunctionalSafetyFITRate,FMDandPinFMASNVA990–AUGUST2020SubmitDocumentFeedbackCopyright2020TexasInstrumentsIncorporatedIMPORTANTNOTICEANDDISCLAIMERTIPROVIDESTECHNICALANDRELIABILITYDATA(INCLUDINGDATASHEETS),DESIGNRESOURCES(INCLUDINGREFERENCEDESIGNS),APPLICATIONOROTHERDESIGNADVICE,WEBTOOLS,SAFETYINFORMATION,ANDOTHERRESOURCES"ASIS"ANDWITHALLFAULTS,ANDDISCLAIMSALLWARRANTIES,EXPRESSANDIMPLIED,INCLUDINGWITHOUTLIMITATIONANYIMPLIEDWARRANTIESOFMERCHANTABILITY,FITNESSFORAPARTICULARPURPOSEORNON-INFRINGEMENTOFTHIRDPARTYINTELLECTUALPROPERTYRIGHTS.
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