电流eset

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cnZHCS998–JULY2012双双路路12V保保护护和和阻阻断断控控制制器器查查询询样样品品:TPS2456A1特特性性说说明明2TPS2456A改改进进了了电电源源转转换换率率抗抗噪噪性性TPS2456A是一款双路,12V,通道保护(热插拔)和阻断(ORing)控制器,此控制器提供浪涌电流控制、双双路路12V保保护护和和阻阻断断控控制制电流限制、过载保护和反向电流阻断.
电流感应拓扑独独立立的的电电流流限限制制和和快快速速跳跳闸闸提供准确的电流限制以及电流限制和快速跳闸阈值的独阻阻断断允允许许多多输输入入ORing冗冗余余控控制制立设置.
电电源源正正常常和和故故障障输输出出模模拟拟电电流流监监视视器器输输出出当一个输入被短路时,ORing控制使用一个金属氧化-40°C至至125°C运运行行温温度度范范围围TJ物半导体场效应晶体管(MOSFET)来阻断反向电流.
四四方方扁扁平平无无引引线线(QFN)36封封装装与电源电压和反馈网络严密匹配的系统能够从两个电源同时供电.
应应用用范范围围MONx输出提供一个负载电流的准确模拟指示.
高高级级电电信信计计算算平平台台(ATCA)载载波波板板AdvancedMC插插槽槽可在无阻断的情况下使用保护电路,并且可在无保护的刀刀片片服服务务器器情况下使用阻断.
内部连接防止基基站站TPS2456和TPS2456A有完全一样电气特性表.
可可配配置置为为TPS2456A已经减少了对于输入电源转换率变化的灵–1个个源源,,2个个负负载载敏度.
建议在所有全新应用中使用.
–2个个源源,,1个个负负载载–2个个源源,,2个个负负载载Figure1.
TwoSources,OneLoadApplicationDiagram1Pleasebeawarethatanimportantnoticeconcerningavailability,standardwarranty,anduseincriticalapplicationsofTexasInstrumentssemiconductorproductsanddisclaimerstheretoappearsattheendofthisdatasheet.
2AdvancedMCisatrademarkofPICMG.
PRODUCTIONDATAinformationiscurrentasofpublicationdate.
Copyright2012,TexasInstrumentsIncorporatedProductsconformtospecificationsperthetermsoftheTexasInstrumentsstandardwarranty.
ProductionprocessingdoesnotEnglishDataSheet:SLVSBI8necessarilyincludetestingofallparameters.
TPS2456AZHCS998–JULY2012www.
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cnThesedeviceshavelimitedbuilt-inESDprotection.
TheleadsshouldbeshortedtogetherorthedeviceplacedinconductivefoamduringstorageorhandlingtopreventelectrostaticdamagetotheMOSgates.
PRODUCTINFORMATION(1)DEVICETEMPERATUREPACKAGEMARKINGTPS2456ARHH–40°Cto85°CQFN36(6mm*6mm)2456A(1)ForpackageandorderinginformationseethePackageOptionAddendumattheendofthisdocumentorseetheTIWebsiteatwww.
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THERMALINFORMATIONTPS2456ATHERMALMETRIC(1)RHHUNITS36PINSθJAJunction-to-ambientthermalresistance(2)32θJC(top)Junction-to-case(top)thermalresistance(3)23θJBJunction-to-boardthermalresistance(4)11°C/WψJTJunction-to-topcharacterizationparameter(5)0.
5ψJBJunction-to-boardcharacterizationparameter(6)10θJC(bottom)Junction-to-case(bottom)thermalresistance(7)2.
1SPACER(1)有关传统和全新热度量的更多信息,请参阅IC封装热度量应用报告(文献号:SPRA953).
(2)在JESD51-2a描述的环境中,按照JESD51-7的规定,在一个JEDEC标准高K电路板上进行仿真,从而获得自然对流条件下的结至环境热阻抗.
(3)通过在封装顶部模拟一个冷板测试来获得结至芯片外壳(顶部)的热阻.
不存在特定的JEDEC标准测试,但可在ANSISEMI标准G30-88中找到内容接近的说明.
(4)按照JESD51-8中的说明,通过在配有用于控制PCB温度的环形冷板夹具的环境中进行仿真,以获得结至电路板的热阻.
(5)结至顶部的特征参数,(ψJT),估算真实系统中器件的结温,并使用JESD51-2a(第6章和第7章)中描述的程序从仿真数据中提取出该参数以便获得θJA.
(6)结至电路板的特征参数,(ψJB),估算真实系统中器件的结温,并使用JESD51-2a(第6章和第7章)中描述的程序从仿真数据中提取出该参数以便获得θJA.
(7)通过在外露(电源)焊盘上进行冷板测试仿真来获得结至芯片外壳(底部)热阻.
不存在特定的JEDEC标准测试,但可在ANSISEMI标准G30-88中找到了内容接近的说明.
ABSOLUTEMAXIMUMRATINGS(1)OverrecommendedjunctiontemperaturerangeandallvoltagesreferencedtoGND,unlessotherwisenoted.
VALUEPINSORPINGROUPSUNITSMINMAXGAT1x,GAT2x–0.
330VINx,OUTx,SENPx,SENMx,SETx,ENx,FLTx,PGx,ORENx–0.
320VCTx,MONx–0.
35VFLTx,PGxcurrentsinking5mAMONxcurrentsourcing5mAVINTcurrent–11mAHumanBodyModel2kVESDChargedDeviceModel0.
5kVJunctionTemperatureInternallyLimited°C(1)Stressesbeyondthoselistedunderabsolutemaximumratingsmaycausepermanentdamagetothedevice.
Thesearestressratingsonly.
Functionaloperationofthedeviceunderanyconditionsbeyondthoseindicatedunderrecommendedoperatingconditionsisnotimplied.
Exposuretoabsolutemaximumratedconditionsforextendedperiodsoftimemayaffectdevicereliability.
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cnZHCS998–JULY2012RECOMMENDEDOPERATINGCONDITIONSOverrecommendedjunctiontemperaturerangeandallvoltagesreferencedtoGND,unlessotherwisenoted.
MINTYPMAXUNITVINx8.
51215VIMONx1001000AGAT1x,GAT2xboardleakagecurrent(1)–11AVINTbypasscapacitance1100250nFOperatingjunctiontemperaturerange,TJ–40125°C(1)ThisconditionappliestothePCBandisnotalimitontheTPS2456A.
ELECTRICALCHARACTERISTICSCommonconditions(unlessotherwisenoted)are:INA=INB=SENPA=SENPB=SENMA=SENMB=SETPA=SETPB=12V,ENA=ENB=ORENA=ORENB=3V,CTA=CTB=GND,RMONA=RMONB=6.
81kΩ,allotherpinsopen,–40°C≤TJ≤125°CPARAMETERTESTCONDITIONSMINTYPMAXUNITEnableInput–ENx,ORENxThresholdvoltageVINx↑1.
251.
351.
45VHysteresis205080mVPullupcurrentENx=ORENx=0V,currentsourcing5815AInputbiascurrentENx=ORENx=17V,currentsinking615ATurnofftime(1)(2)ENxdeassertstoVOUTx10.
63V.
GND23GND–Connectpintoground.
GND24GND–Connectpintoground.
GND25GND–Connectpintoground.
PGA26OAPowergoodoutput,activelow,assertswhenVOUTA>10.
63V.
FLTA27OAFaultoutput,activelow,assertedwhenAfaulttimerrunsout.
GND28GND–Connectpintoground.
ENB29IBEnable,(activehigh).
GAT1A30OAProtectiontransistorgatedrive.
ENA31IAEnable,(activehigh).
GND32GNDAConnectpintoground.
OUTA33I/OAOutputvoltagemonitorandbiasinput.
GAT2A34OABlockingtransistorgatedrive.
CTA35I/OAConnectCTAfromCTAtoGNDtosetthefaulttimerperiod(seetheDETAILEDPINDESCRIPTIONS).
INA36PWRAControlpowerinput–connecttoinputsupply.
PAD–––SolderpadtoGND.
(1)SpecifieswhetherthispinispartofAchannel,Bchannel,oriscommontoboth(-).
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cnZHCS998–JULY2012DEVICEPINOUT(TOPVIEW)DETAILEDPINDESCRIPTIONSTheTPS2456Asupportstwo12-Vprotection(hotswap)andblocking(ORing)channelsdesignatedAandB.
WherethereareseparatepinsforbothAandBchannels,thepinnameisshownwithanxinplaceofAorBtodescribethefunction.
Forexample,referencestoCTxwouldbethesameasCTAorCTB.
ProgrammingcomponentsarereferredtointhetextbyreferencedesignatorsusedinFigure1.
CTx–AcapacitorfromCTxtoGNDsetstheperiodVGAT1xcanbelow(VGAT1xVOUTX.
Aninternal200kΩresistorpullsthispintoVINT.
ORENxmaybeleftopenwhenblockingisnotused,ordoesnotrequireactivecontrol.
OUTx–Sensestheoutputvoltageofthechannel.
Thisvoltageisusedbythebiasing,blocking,andpowergoodcircuits.
PGx–Activelowopen-drainoutput.
AlowonPGxindicatesthatVOUTxhasexceeded10.
63V,andhasnotfallenbelow10.
50V.
Thesethresholdsareinternallyset,andmodifyingtheOUTxconnectionmayeffectblockingoperation.
SENMx–SensesthevoltageontheloadsideofRSENSExforusebythefasttripandcurrentlimitingcircuits.
SENPx–SensesthevoltageonthesourcesideofRSENSExforusebythefasttrip,UVLOandblockingcircuits.
ThefasttripovercurrentshutdownisactivatedataVSENP-SENMof0.
1V.
UVLOtripswhenSENPxgoesbelow8.
5Vformorethan440ns(nominal),295ns(worstcase).
SETx–AresistorconnectedfromthispintoSENPxsetsthecurrentlimitlevelinconjunctionwithRSENSExandRMONxasdescribedinEquation1throughEquation4.
VINT–Thispinconnectstotheinternal2.
35Vrail.
A0.
1Fcapacitormustbeconnectedfromthispintoground.
VINTisnotdesignedtobeageneral-purposebiasrail.
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cnZHCS998–JULY2012TYPICALCHARACTERISTICSSUPPLYCURRENTvsTEMPERATURESUPPLYCURRENTvsINPUTVOLTAGEFigure6.
Figure7.
CURRENTLIMITTHRESHOLDvsTEMPERATUREBLOCKINGTURNOFFTHRESHOLDvsTEMPERATUREFigure8.
Figure9.
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cnTYPICALCHARACTERISTICS(continued)BLOCKINGTURNONTHRESHOLDvsTEMPERATUREFigure10.
Figure11.
Startupinto500Ω,830FLoadFigure12.
Startupinto80Watt,830FLoad10Copyright2012,TexasInstrumentsIncorporatedTPS2456Awww.
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cnZHCS998–JULY2012TYPICALCHARACTERISTICS(continued)Figure13.
ShortCircuitUnderFullLoad(6.
7A)WideFigure14.
ShortCircuitUnderFullLoad(6.
7A)ZoomViewFigure15.
StartupintoShortCircuitFigure16.
OverloadedwhileSupplying6.
7ASYSTEMOPERATIONINTRODUCTIONTheTPS2456Acontrolstwo12-Vchannels,orpowerpaths.
Thechannelscandrawfromasinglecommonsupply,orfromtwoindependentsupplies.
ThefollowingsectionsdescribetheTPS2456Aoperationandprovideguidancefordesigningsystemsaroundthisdevice.
CONTROLLOGICANDPOWER-ONRESETTheTPS2456AcircuitrydrawsbiaspowerfromanyoftheINxorOUTxpinsthroughaninternalpreregulatorthatgeneratesVINT.
AbypasscapacitorfromVINTtogroundprovidesdecouplingandoutputfilteringfortheinternalcircuits.
BiassupplyORingallowstheinternalcircuitrytofunctionregardlessofwhichchannelsreceivepowerorareinafaultedstate.
ThefourexternalMOSFETdrivepins(GAT1A,GAT1B,GAT2A,andGAT2B)areheldlowduringstartuptoensurethatthechannelsremainoff.
WhenthevoltageontheinternalVINTrailexceedsapproximately1V,thepower-onreset(POR)circuitinitializestheTPS2456Aandallowsnormaloperation.
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cnENABLEFUNCTIONSTheTPS2456Ahastwoexternalenablepinsforeachofthechannels.
TheGAT1xandGAT2xpinsareheldlowwhentheENxpinislow.
AhighonENxenablesGAT1xfornormalcontrolbythestartupandprotectionfeatures.
TogglingENxlow,thenhigh,clearsalatch-offconditionafterafaulthasoccurredonthechannel.
TheGAT2xpinisheldlowwhentheORENxorENxpinsarelow.
Thereverseblockingcomparator-drivenstatemachinecontrolsGAT2xwhenORENxandENxpinsarehigh.
ENxORENxPROTECTIONBLOCKING(M1x,GAT1x)(M2x,GAT2x)00Disabled(low)Disabled(low)01Disabled(low)Disabled(low)10EnabledDisabled(low)11EnabledEnabledEachofthefourenablepinshasaninternal200kΩpullupresistortoVINT.
POWERGOOD(PGx)OUTPUTSTheTPS2456Aprovidesanactive-lowopen-drainPowerGood(PGx)outputforeachchannel.
PGxgoeslow(outputgoodindication)forrisingVOUTxexceeding10.
63VandPGxgoeshighforfallingVOUTxbelow10.
5V.
A100sdeglitchfilteraidsinavoidingfalseindicationsduetonoise.
FAULT(FLTx)OUTPUTSTheTPS2456Aprovidesanactive-lowopen-drainfaultoutputforeachchannel.
TheFLTxoutputpullslowwhenthechannelhasremainedincurrentlimitlongenoughforthefaulttimertoexpire(VCTx>1.
35V).
Achannelexperiencingafaulttimeoutshutsdownandlatchesoff.
Togglethefaultedchannel'sENxlowandhightoclearthefaultandre-enablethechannel.
CURRENTLIMITANDFASTTRIPTHRESHOLDSLoadcurrentismonitoredbysensingthevoltageacrossRSENSEx,whosevaluestypicallylieintherangeof4mΩto10mΩ.
Eachchannelfeaturestwodistinctthresholds,acurrent-limitthresholdandafast-tripthreshold.
Thecurrentlimitthresholdsetstheregulationpointofafeedbackloop.
Ifthecurrentflowingthroughthechannelexceedsthecurrentlimitthreshold,VGAT1xisreduced,forcingtheMOSFETintolinearoperation.
Thiscausesthecurrentflowingthroughthechanneltosettletothevaluedeterminedbythecurrentlimitthreshold.
Forexample,whenamodulefirstpowersup,itdrawsaninrushcurrenttochargeitsloadcapacitance.
Thecurrent-limitloopensuresthatthisinrushcurrentdoesnotexceedthecurrentlimitthreshold.
M1willdissipatemuchmorepowerincurrentlimitthanduringnormaloperation.
ThefaulttimercircuitlimitstheintervalM1operatesinthiscondition.
Thereisadelaybeforechannelcurrentisregulatedfollowingtheonsetofanoverloadduringnormaloperation.
Thecurrentlimitcircuitisabletosink30AfromtheprotectionMOSFETgate.
ThedelayistheresultoftheMOSFET'sCISSdischargefrom(VINx+13V)to(VINx+VT_M1x)whereVT_M1xistheprotectionMOSFET'sthresholdvoltage.
Overloadsbetweenthecurrentlimitandthefasttripthresholdwillbepermittedforthisperiod.
ThisisdemonstratedbyFigure16.
CurrentsabovethefasttripthresholdarehandledbyrapidlyturningtheprotectionMOSFEToffwithastronggatepulldownthatisdrivenbya10soneshot.
Thefaulttimerstartsandthegateisallowedtoriseaftertheoneshotcompletesinwhatresemblesanormalstartup.
ThefasttripthresholdprotectstheMOSFETandchannelcomponentsagainstasevereshortthatcreatesahighcurrentfasterthanthecurrent-limitloopcancontrol.
If(VSENPx–VSENMx)exceedsthe100mVfasttripthreshold,GAT1xandGAT2xareimmediatelypulledtoGNDforaminimumof10s.
Thechannelturnsbackonslowly,allowingthecurrentlimitfeedbacklooptimetotakeover.
ThefaulttimerperiodlimitsthedurationtheMOSFETwillseethisstress.
ThisisdemonstratedbyFigure13andFigure14.
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cnZHCS998–JULY2012WhentheTPS2456Aprotectsasupplyoutputinconfigurationsthatallowtheloadstohotplug,payspecialattentiontocoordinatingloadsurges(duetoinputcapacitance)andthefasttripthreshold.
Thefasttripthresholdmayneedtobeset2–5timeshigherthanthecurrentlimittoaccommodatethis.
CaremustalsobetakeniftheINxvoltagescanhavefastrisingtransients.
TheresultingchargecurrenttocapacitorsonOUTxcanpotentiallyexceedthefasttripthreshold.
FASTTRIPANDCURRENTLIMITINGFigure17showsasimplifiedblockdiagramofthefasttripandcurrentlimitcircuitry.
EachchannelrequiresanexternalN-channelprotectionMOSFETandthreeexternalresistors.
Theseresistorsallowtheusertoindependentlysetthefasttripthresholdandthecurrentlimitthreshold,asdescribedbelow.
Thefasttripfunctionisdesignedtoprotectthechannelagainstshort-circuitevents.
IfthevoltageacrossRSENSExexceeds100mV,theTPS2456AimmediatelyturnsofftheprotectionMOSFET,M1x.
ThenominalfasttriplimitIFTxisdefinedinEquation1.
(1)ThecurrentlimitcircuitregulatesVGAT1xtocontrolthechannelcurrentfromexceedingILIMITx.
Thecurrentlimitcircuitryincludestwoamplifiers,A1andA2,asshowninFigure17andFigure4.
AmplifierA1forcesthevoltageacrossexternalresistorRSETxtoequalthevoltageacrossexternalresistorRSENSEx.
ThecurrentthatflowsthroughRSETxalsoflowsthroughexternalresistorRMONx,generatingavoltageontheMONxpinperEquation2.
(2)AmplifierA2implementsaslow-reactingcurrentlimit.
AslongasVMONxislessthan0.
675V,GAT1xoperatesnormally.
WhenVMONxexceeds0.
675V,amplifierA2causesasmallcurrenttobedrawnfromGAT1x.
Thegate-to-sourcevoltageofM1xdropsuntilloadcurrentisreducedandthetwoinputsofamplifierA2balance.
ThecurrentflowingthroughthechannelthenequalsILIMITxperEquation3.
(3)(4)TherecommendedvalueofRMONxis6.
81kΩ.
Thisresistorshouldbegreaterthan675Ωtopreventexcessivecurrentsfromflowingthroughtheinternalcircuitry.
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cnFigure17.
OvercurrentProtectionCircuitryTURNONANDINRUSHSLEWRATECONTROLOneofthemainfunctionsofaprotectiondeviceistoprovideamethodofhot-pluggingandstartingupaunitinalow-stressandcontrolledmanner.
Startingincludestheabilitytochargetheoutputcapacitance(onOUTx)withoutoverburdeningtheinputpowerbuswhileminimizingthestressontheprotectionMOSFET.
Twopossiblecharge-ratecontrolmethodsarepossiblewiththeTPS2456A,currentlimitedandgatedv/dtcontrolled.
Asnormallyconfigured,thegatedv/dtturn-onslewrateisdescribedbyEquation5.
(5)whereIGAT1x(SOURCING)equalsthecurrentsourcedbytheGAT1xpin(nominally30A)andCGate-M1xisthereversetransfercapacitance,CRSS.
AverageCRSSmaybeapproximatedusingtheMOSFETVGATEvs.
QggraphasCRSS=ΔQg/VTwhereΔQgisthewidthoftheplateauregionandVTisthegateplateauvoltage.
Tosimplifythecalculation,theMOSFETgatecapacitancesareassumedtobefixed,whileinreality,thereisavoltagedependency.
TheoutputvoltagetracksVGATE_M1xonceithasexceededtheMOSFETthresholdvoltageifcurrentlimitisnotactive.
Theinrushcurrentisdefinedbythefollowingequationforapurelycapacitiveload.
StartupofaswitchingconverterloadduringinrushshouldbeavoidedbyuseofPGxtocontroltheconverter.
(6)Theactualinrushcurrentisthelesserofthecurrentlimit(Equation3)ordv/dt-limitedinrushcurrent.
Toreducetheslewrate,increaseCGate-M1xbyconnectingadditionalcapacitancefromGAT1xtoground.
Placearesistorofatleast1000ΩinserieswiththeadditionalcapacitancetopreventitfrominterferingwiththefastturnoffoftheMOSFET.
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cnZHCS998–JULY2012FAULTTIMERPROGRAMMINGEachchannelrequiresanexternalcapacitorCTxconnectedbetweentheCTxpinandground.
TheTPS2456Asources10AintoCTxwhenthegatevoltageislow((VGAT1x–VINx)6V)andFLTxisnotactive.
ThenominalfaulttimetfxisdefinedbyEquation7.
(7)Converterstartuptypicallysetstheminimumtfx.
Therearethreeimportantintervalstoconsiderwhencalculatingthetimetosettfx,initialchargeoftheMOSFETgatetothethresholdvoltage,theintervalasVOUTxrisestoVINx,andtheintervalforVGAT1xtoexceedVINxby6V.
AssumethataconstantCISSischargedinthefirstandthirdperiodssincetheMOSFETdrainandsourcevoltagesdonotchange.
Themiddleperiodmaybecontrolledbyeithercurrentlimitorgatedv/dtlimitaspreviouslydiscussed.
LetVTM1xbetheMOSFETgatevoltagetosustaintheinrushcurrent.
(8)Manyoftheseparametershavewidetolerance,thus,theaboveapproximationprovidesaninitialestimate.
ProvidesufficientmarginintheCTxselectiontoassurethechannelstartsreliablywhilenotbecomingoverlylong.
ShorterfaulttimesreducethestressesimposedontheprotectionMOSFETunderfaultconditions,permittingtheuseofsmaller,lessexpensiveprotectionMOSFETs.
ENxRESETPERIODTheTPS2456Awilllatchoffafteracurrentlimitthatpersistslongenoughtotripthefaulttimer.
TheTPS2456Amaybere-enabledbycyclingtheENxfalse(low),thenhigh.
ThereisaminimumlowperiodrequiredtofullyresetCCTxthatisdeterminedbytheRxCperiodwhereRistheinternaldischargeresistance.
CalculatetheminimumperiodastENx_LOW_MIN=CCTx_MAXx400Ωx3.
AssumingCCTx_MAXis22nFat20%tolerance,tENx_LOW_MIN=(22nFx1.
2)x400x3=31.
7s.
tENx_LOW_MINshouldalwaysbegreaterthan100ns.
BLOCKINGOPERATIONEachchannelmayuseanexternalMOSFET(M2x)toprovidereverseblocking.
ThisfeatureisoftenusedwheretwoinputsareORedtogethertoacommonoutputforredundancy.
Blockingprotectsthecommonoutputfrombeingdrawndownifaninputisshorted,andmaintainstheindependenceofbothinputs.
Blockingmaynotberequiredinallsystemtopologies.
TheTPS2456ApullstheGAT2xpinhighwhenV(INx–OUTx)exceeds10mV,anditpullsthepinlowwhenthisdifferentialfallsbelow–3mV(VOUTxisgreaterthanVINx).
Thesethresholdsprovide13mVofhysteresistohelppreventfalsetriggeringasshowninFigure18.
Thistechniquewillallowsomereversecurrenttoflow,butprovidespositivedetectionintheeventofarealfault.
TheblockingMOSFETisorientedsoitsbodydiodeconductsforwardcurrentandblocksreversecurrent.
ThebodydiodedoesnotnormallyconductcurrentbecausetheMOSFETturnsonwhenthevoltagedifferentialacrossitexceeds10mV.
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cnFigure18.
BlockingThresholdsAPPLICATIONINFORMATIONSYSTEMDESIGNCONSIDERATIONSTheTPS2456Ahastwoindependent12Vsectionswhichprovideprotectionandblocking(ORing).
Thesesectionsmaybeusedinmultipleconfigurations.
TPS2456Aonthepowerinputofasystem–Tworedundantinputpowerrailstoasingleoutput(seeFigure1)–Blockingprotectsoutputwhenoneoftheinputsisshorted–Twoindependentloadspoweredbytwoseparateoronecommoninputrail–Blockingnotrequired–TworedundantinputrailsORed(noprotection)toonecommonoutputTPS2456Aonthepoweroutputofasystem–Uptotwooutputrailswithprotection–Protectionisolatesfaultedoutputbus–Enablecanbeusedtoturnoutputonandoff–Uptotwooutputpowerrailswithprotectionandblocking–UsedwheremultipleoutputsaretiedtogetherThesystempowerarchitecturedrivesthetopologythatbestsuitsaparticulardesign.
DESIGNEXAMPLE:CURRENTLIMITEDSTART-UPThefollowingexampleisforasinglechannelprotectioncircuitusingcurrent-limitedinrushcontrol.
Thedesignofthesecondchannelwouldfollowthesameprocedureandisnotshownsinceitisredundant.
Forthisdesignexample,asystemboardwith1000Fofcapacitanceandadcloadof1.
6Ω(or7.
5A)mustbeabletobehotpluggedintoa12Vmainbussupply.
Themainbussupplyhasapeakfaultcurrentcapabilityof20A.
Operatingabove20Aofcurrentdrawrunstheriskofopeningacircuitbreakerandshuttingthesystemdown.
Theaveragecurrentbudgetedforthesystemboardis7.
5Aundernormalconditions.
Themainbuscansupplyupto10.
1Apeakforupto10msduringstart-uportransientconditions.
Thisprocedureassumesthattheinrushcurrentisnotlimitedbythegatechargerate.
ThebasicsystemblockdiagramisshowninFigure19.
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cnZHCS998–JULY2012Figure19.
12VMainBusSelectRSENSExThefirststepistocalculateRSENSExwhichsetsthefastcurrenttrippoint,IFTx.
ThisisthemaximumcurrentthatcanpassthroughM1xandismeanttoprotectagainstshortcircuits.
CalculateRSENSExusingEquation9forapeakfaultcurrent(IFTx)of20A.
(9)TheRSENSExresistorisinserieswiththemainpowerpathandshouldhaveapowerratingsufficienttosupportthefullloadcurrent.
The12Vmainbushasbudgeted10.
1Aforthisboard,sothisisthevalueoflimitusedforfurthercalculationsincludingthepowerdissipatedinRSENSEx.
ThepowerdissipatedbyRSENSEiscalculatedusingEquation10.
Ahigherwattageratingshouldbeusedbasedonlocalderatingpractice(forexample50%).
(10)SelectRSETxNext,RSETxiscalculatedtosetthechannelcurrentlimit(ILIMITx)to10.
1A.
RMONxisalsoavariableinthecalculationofRSETx.
Usetherecommended6.
81kΩforRMONx(althoughothervaluescanbeused)and10.
1AforILIMITxtocalculateRSETx.
(11)ChooseRSETxasthecloseststandardvalue,511Ω.
EstimateOutputChargeTimeThesystemcanprovide10.
1Aofpeakcurrentfor10ms.
Thiscurrentcanbeusedforstart-upofthesystemboardaslongastheoutputcapacitancecanbechargedupto12Vinlessthan10mswhilealsosupplyingcurrenttotheloadresistanceconnectedinparalleltotheoutputcapacitor.
ThechargetimeisestimatedusingEquation12.
Forthisequation,VOUTxisthefinalnominalvoltagefortheboard(12V),RLOADisthedcloadoftheboard(1.
6Ω),andthereisasmallamountoftimeforthepasstransistor'sgatecapacitancetochargetothethresholdvoltage.
Thistime,typicallyaround100s,isaddedtotheendoftheequationtoprovideabetterestimateofthetotalstart-uptime.
Copyright2012,TexasInstrumentsIncorporated17TPS2456AZHCS998–JULY2012www.
ti.
com.
cn(12)(13)(14)Theestimatedtimetochargetheoutputis2.
27ms.
ItissafetoallowtheboardtopowerupusingthepeakcurrentlimitbecausetCHGisbelowthe10mstarget.
Equation12assumesthereisaresistiveloadontheoutputduringtherampupsotheoutputvoltagehasan"RC"shape.
Theoutputcapacitancechargeslinearlyiftheloadispurelycapacitive,simplifyingthechargetimeequationtothefollowing.
(15)SelectM1xThenextdesignstepistoselectM1x.
TheTPS2456AisdesignedtouseNchannelMOSFETsasprotectiondevices.
ThemaximumMOSFETgatetosourcevoltagerating,VGS-MAX,mustbehighenoughtosupportthehighestofthegatedrive(14.
5V)orinputvoltage.
Thenextfactortoconsideristhedraintosourcevoltagerating,VDS-MAX,oftheMOSFET.
Fromadcperspective,theMOSFETneedstowithstandtheinputpowersupplyvoltageof12Vforthisexample.
However;theMOSFETcanbeexposedtohighvoltagespikesduringfaultconditions.
Forthisreason,aMOSFETwithasubstantiallyhigherVDS-MAXratingimprovesthesystemreliabilityandprovidesvoltageheadroomfortransientprotection(snubber,TVS,diodes,andsoon).
LookforaVDS-MAXratingwithaminimumoftwiceoftheinputpowersupplyvoltage.
Next,thedcpowerlossoftheMOSFETmustbeconsidered.
ThepowerdissipationoftheMOSFETisdirectlyrelatedtotheRDS(on)oftheMOSFET.
ThedcpowerdissipationfortheMOSFETcanbecalculatedusingEquation16.
(16)Takingthesefactorsintoconsideration,theTICSD16403Q5Awasselectedforthisexample.
TheCSD16403Q5AhasaVGS-MAXratingof16V,VDS-MAXratingof25V,anRDS(on)of2.
2mΩ,andanRθJA-MAXof51°C/W.
Duringnormalcircuitoperation,theMOSFETcanhaveupto10.
1Aflowingthrough,whichequatesto0.
22W(I2xR)andan11°Criseinjunctiontemperature(PxRθJA-MAX).
ThisiswellwithinthedatasheetslimitsfortheMOSFET.
Thepowerdissipatedduringafault(e.
g.
outputshort)issubstantiallylargerthanthesteady-statepower.
ThepowerhandlingcapabilityoftheMOSFETneedstobecheckedduringfaultconditions.
MostMOSFETdatasheetsprovideaSafeOperatingArea(SOA)plot.
ThisplotcanbeusedtocheckiftheMOSFETcansurvivethepowerformatransientfaultcondition.
Figure20showstheSOAcurvefortheQSD16403Q5A.
Themaximumfaultcurrentissetto20Aforthe12Vinputbus.
ThispointcanbelocatedonFigure20.
ThediagonallinestellthelengthoftimethistransientcanbesafelyappliedtotheQSD16403Q5A.
Thetransistorcansurvivea12V,20Atransientforapproximately9ms.
18Copyright2012,TexasInstrumentsIncorporatedTPS2456Awww.
ti.
com.
cnZHCS998–JULY2012Figure20.
DrainToSourceVoltageTheturnofftimeoftheTPS2456AandMOSFETshouldbetakenintoaccount.
TheTPS2456Adetectsthefaultconditionassoonasthecurrentthroughthesenseresistorreaches20A.
Thereisa300nsmaximumpropagationdelayfortheTPS2456AtostartdischargingtheMOSFETgate.
TheMOSFEThasanadditionalturn-offdelayduetogatedischarge(seetheElectricalCharacteristicstable,Sinkingcurrent-Fastturnoff).
ThetotaldelayfortheTPS2456AandtheCSD16403Q5Aisapproximately310ns.
Thefaultcurrentcontinuestoriseabove20Aforthisperiod.
Theriseofthefaultcurrentisdeterminedbyanyinductanceandresistanceinthepowerpathaswellastheimpedanceoftheinputvoltagesource.
Continuingtofollowthe12VlineupontheSOAcurve,itcanbeseenthattheCSD16403Q5Acouldhandlepeakcurrentsupto180Afor1ms,givingsubstantialmargininthisdesign.
Thismakesthistransistoragoodchoiceforthisapplication.
OutputChargeTimeRefinementAmoreaccuratechargetimecanbecalculatedusingEquation17,nowthattheMOSFEThasbeenchosen.
ThisisthesameasEquation15,butthe100stermisreplacedwiththevariablesthatdeterminethetimeittakestochargethegateoftheMOSFETuptothethresholdvoltage.
ThethresholdvoltageusedinthisequationshouldbethevoltagewheretheMosfetstartstoconducthighercurrents.
ThiscanbefoundintheMOSFETdatasheetfromgraphsshowingIDvs.
VGS.
FortheCSD16403Q5A,theVT_M1xis1.
6V,andCISSis2040pF.
ThetermIGinEquation17istheGAT1xsourcingcurrent,typically30A.
Usingthesevalues,Equation17givesachargetimeof2.
28ms(17)SelectCTxThenextstepistodeterminetheminimumfaulttimerperiod.
Intheprevioussection,thechangetimecalculationyielded2.
28ms.
Thisistheamountoftimeittakestochargetheoutputcapacitoruptothefinaloutputvoltage.
However,thefaulttimerusesthedifferencebetweentheinputvoltageandthegatevoltagetodetermineiftheTPS2456Aisincurrentlimit.
ThefaulttimercontinuestorununtilVGATE_M1xis6Vabovetheinputvoltage.
Someadditionaltimemustbeaddedtothechargetimetoaccountforthisadditionalgatevoltagerise.
TheminimumfaulttimertimecanbecalculatedusingEquation18.
(18)Copyright2012,TexasInstrumentsIncorporated19TPS2456AZHCS998–JULY2012www.
ti.
com.
cnUsingtheexamplenumbersintheaboveequationleadstoaminimumfaulttimertimeof2.
688ms.
Thefaulttimermustbesettoavaluehigherthan2.
688mstoavoidturningoffduringstart-upbutlowerthananymaximumtimelimit.
ThereisamaximumtimelimitsetbytheSOAcurveoftheMOSFET.
ReferringbacktoFigure20,theCSD16403Q5ASOAcurve,theMOSFETcantolerate10.
1Awith12Vacrossitforapproximately20ms.
However;theinputpowersupplycanonlysupplythe10.
1Afor10ms.
Therefore,thefaulttimershouldbesettobetween2.
688msand10ms.
Forthisexample,select8mstoallowforvariationofsystemparameterssuchastemperature,load,componenttolerance,andinputvoltage.
ThetimingcapacitoriscalculatedinEquation19as59nF.
Selectathenexthigheststandardvalue,62nF,yieldingan8.
37msfaulttime.
(19)BlockingDevice,M2xSincethisexampleusesasinglechannel,thereisnoneedfortheblockingMOSFET,anditcanbeleftoutofthecircuit.
NoconnectionneedstobemadetotheGAT2xorORENxpins.
DESIGNEXAMPLE:GATERAMPLIMITEDSTARTUPInthefirstexample,theoutputcapacitanceischargedincurrentlimit.
Insomeapplications,thecurrentlimitistheabsolutemaximumthatthecircuitshouldsee,sochargingtheoutputupincurrentlimitisnotanoption.
Inthiscase,itisnecessarytoslowdowntheoutputvoltagerampsothatthecurrentlimitisnotreached.
ThiscanbedonebyaddingadditionalcapacitancetoM1x'sgate.
Thegateofthepasstransistorisdrivenbya30A(typical)currentsource.
Thecurrentchargesthegatetosourceandgatetodrain(Crss)capacitance,producingavoltagerampatthegate.
Thetimeoftherampcanbelengthenedbyaddingacapacitor,CADD,betweenthegateandground.
A1kΩresistorshouldbeplacedinserieswiththeadditionalcapacitanceasshowninFigure21.
Figure21.
WithCADD,theoutputvoltagerampisequalto:(20)Thepeakcurrent,IINX-PEAK,thatisreachedwiththenewramprateis:(21)20Copyright2012,TexasInstrumentsIncorporatedTPS2456Awww.
ti.
com.
cnZHCS998–JULY2012CADDcanbeadjustedsothatIINx_PEAKislessthanILIMITxavoidingcurrentlimitstart-up.
Usingacontrolledgateramprequireslowerpeakcurrent,buttakeslongertochargetheoutputcapacitance.
Thelengthofthefaulttimeneedstobeselectedtoaccommodatethislongerrampuptime.
TheminimumtimethefaulttimershouldbesettoisdescribedbyEquation22.
(22)BYPASSCAPACITORSItisagoodpracticetoprovidelow-impedanceceramiccapacitorbypassingofINxandOUTx.
Valuesintherangeof10nFto1Farerecommended.
Somesystemtopologiesareinsensitivetothevaluesofthesecapacitors;however,somearenotandprefertominimizethevalueofthebypasscapacitor.
Inputcapacitanceonaplug-inboardmaycausealargeinrushcurrentasthecapacitorchargesthroughthelowimpedancepowerbuswheninserted.
Thisstressestheconnectorcontactsandcausesashortvoltagesagontheinputbus.
Smallamountsofcapacitance(e.
g.
,10nFto0.
1F)areoftentolerableinthesesystems.
Insystemswithlittleornobusholdupcapacitanceonthebackplane,itiscommontohavenocapacitanceattheboardinput.
Thishelpsminimizetransientsatplugin.
Filtercapacitorsattheoutputofaredundantplug-inboardareusefulforcontrollingvoltagetransients,buttheymaycancauseproblemswhentheboardisinsertedintoanactivebus.
Iftheoutputcapacitorchargefromanactivebusisnotlimited,theinrushsurgemightengagetheactivesupply'sfast-tripshutdown.
OnepossiblesolutionistoputafewOhmsofresistanceinserieswiththecapacitortolimitinrushbelowthefasttriplevel.
TRANSIENTPROTECTIONIftheTPS2456Aisusedinapplicationswhichhavelargeinputandoutputcapacitors,voltagetransientsduringloadstepsorshortcircuitsarecontrolledandposenoproblems.
TPS2456Adevicesaresometimesdeployedsystemsthatmayhavelong,inductivefeedorloadinterconnections.
Theeffectoftheinductance,withlittlelocalcapacitance,givesrisetopotentialvoltagetransientissues.
AsimplifiedmodelofthisisshowninFigure22.
Channelcurrenttransientsmaybecausedbyeventssuchashot-plug,outputshortswithfastturnoff,orabruptloadchanges.
ThecombinationofinputinductanceandanabruptloaddecreasecausesapositivevoltagespikeontheTPS2456AINPUTpins.
ThecombinationofoutputinductanceandanabruptloaddecreasewillcauseanegativevoltagespikeontheTPS2456AOUTPUT.
ThesetransientshavethepotentialtoexceedtheAbsoluteMaximumRatings,eitherdamagingtheTPS2456Aorcausingundesiredoperation.
NOTE:LP=ParasiticInductance(notallinstancesequal)RP=ParasiticResistance(notallinstancesequal)Figure22.
SystemTransientModelCopyright2012,TexasInstrumentsIncorporated21TPS2456AZHCS998–JULY2012www.
ti.
com.
cnAnanalysismustbeperformedtodeterminetheneedfortransientprotection.
Equation23allowsthedesignertoestimatethevoltagespikeduetocurrentinterruptions.
(23)Where:VINIT=initialvoltageatterminalbeinganalyzedbeforethecurrentisinterruptedL=combinedinductanceoffeedandRTNlinesinserieswithinterruptedcurrentC=capacitanceatpointofcomputationILOAD=currentimmediatelybeforecircuitisopenedAnapproximationfortheinductanceofastraightwireis:L≈[0.
2*length_in_meters*(In(4*length/diameter)–0.
75)]nHThecapacitanceinEquation23,atINPUT,consistsofparasiticcapacitanceandanyintentionalbypasscapacitance.
Thisimpliesthatthetransientscanbecontrolledbytheadditionofsufficientcapacitance.
Equation24canbeusedtocalculatethecapacitancerequiredtolimitthevoltagespiketoadesiredlevelabovethenominalvoltage.
(24)TRANSIENTPROTECTIONSOLUTIONSTypicalprotectionsolutionsinvolvecapacitors,TVSs(TransientVoltageSuppressors)and/oraSchottkydiode.
ATVSandsmallbypasscapacitoratINPUT(seeFigure22)arethemostlikelysolutionstosolveinputvoltageovershoot.
TheTVSmustbeselectedsothatitsclampingisbelowtheAbsoluteMaximumRating(17V)attheanticipatedfaultcurrent.
Forexample,theSMCJ13Adatasheetspecifiesamaximumclampingvoltageof21.
5V(whichexceedstheAbsoluteMaximumvoltage)at69.
7A.
Theactualclampingvoltageatthefaultcurrent(IFT)maybewithintheAbsoluteMaximum;however,theclampvoltageatlowercurrentsmustbeestimatedtoverify.
BymodelingtheTVSasaperfectvoltageclampinserieswitharesistor,theclampingvoltagemaybeestimatedatdifferentcurrentsperEquation25.
(25)ThemaximumpermittedclampingcurrentforthisdeviceisfoundinEquation26.
Thisisaworstcase(low)number.
(26)ASchottkydiodeandcapacitoracrosstheOUTPUT(Figure22)arethemostlikelysolutionstoclampthetransientenergyandlimitthenegativevoltageexcursion.
AlthoughtheSchottkydiodeabsorbsmostoftheenergy,theextremelyfastdi/dtatshutoffallowssomeoftheleadingedgeenergytocouplethroughtheparasiticcapacitancesoftheprotectionandblockingMOSFET(CDS,CGS,CGD)totheGAT1xandGAT2xpins.
Protectionforthesepinsisprovidedby100Ωresistorswhichhavelittleeffectonnormaloperationbutprovidegoodisolationduringtransientevents.
Equation24givesinsightintoselectionoftransientprotectioncapacitorsforbothINPUTandOUTPUT;however,thereareconcernswithaddingalotofcapacitanceinsomesituations.
SeetheBYPASSCAPACITORSsectionregardingconsiderationsandlimitationsPCBlayoutoftheprotectioniscriticaltoitsperformance.
ThelayoutshouldminimizetheimpedancebetweentheTPS2456Aandtheprotectioninordertoprovidethebestclamping.
22Copyright2012,TexasInstrumentsIncorporatedTPS2456Awww.
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com.
cnZHCS998–JULY2012OUTPUTBLEEDRESISTANCETheOUTxpinsourcesasmallamountofcurrentwhenthechannelinputispowered,butdisabledinnon-redundantconfigurations(outputisunpowered).
Theleakagecanbemodeledasa6Vsourceinserieswitha280kΩresistor,allowingapproximately21.
4Aintoashort.
Thisleakagecanchargeahigh-impedanceloadtoapproximately6V.
Ifthisisunacceptable,controltheoutputvoltageinthisstatebyaddingaloadresistorfromOUTxtoGND.
Selecttheresistor,RBLEED,perEquation27,whereVBLEEDisthedesiredmaximumoutputvoltage.
Sincethemodelisnominal,usea25%smallerresistorvalue.
(27)CONTROLLINGFAULTCURRENTinREDUNDANTPOWERTOPOLOGIESSystemtopologiessuchasFigure1areoftenusedtoprovidepowersourceredundancy.
Thispermitstheloadtorunfromeithersource,orpotentiallybothinparallel.
BlockingpermitstheloadtooperateuninterruptedintheeventofeithersourcefailingopenorshortingtoGND.
However,thistopologypermitstheloadtodrawtwicethechannelfaultcurrent(ILIMITx)fortwocloselymatchedsources.
ThesimpleconfigurationofFigure23programsthetotalloadfaultcurrenttoafixedvalueindependentofthenumberofchannelfeedstotheload.
Thecurrentlimitthresholdsnowapplytothesumofthecurrentsdeliveredbytheredundantchannels.
Whenimplementingthisredundantmode,itisrecommendedthatallofthechannelsusethesameRSENSExandRSETxvalues.
Thisconfigurationdoesnotfostersharingorsmoothtransitionsbetweensources,itsimplypermitsthepowertoflowfromthehighersource,butlimitsthemaximumloadcurrenttoafixedvalue.
Figure23.
FixedFaultCurrentApplicationCURRENTFEEDBACKTOASHELFCONTROLLERAshelfcontrollercanmonitorchannelcurrentsbyobservingVMONx,whichisproportionaltothecurrentthroughRSENSEx.
ThevoltageonMONxcanbedirectlysampledwithananalogcircuit(e.
g.
acomparator)orsampledwithanAnalogtoDigitalConverter(ADC)toprovideadigitalrepresentationofthecurrent.
Figure24showsatypicalsystemconfigurationusingamultiplexerandADC(analogtodigitalconverter)tomonitorthecurrentinbothchannelsoftheTPS2456A.
Ithasbeenassumedthatthenormal0Vto0.
675VrangeofVMONxissuitablefortheADCinput.
Ifthisisnotthecase,operationalamplifiercircuitsshouldbeusedtobufferandscalethesesignals.
ItisnotadvisabletoaddcapacitancetotheMONxpinsasthiseffectsthecurrent-limitloop.
Copyright2012,TexasInstrumentsIncorporated23TPS2456AZHCS998–JULY2012www.
ti.
com.
cnFigure24.
TheoutputoftheMONxpinisacurrentproportionaltothecurrentpassingthroughthepasstransistorasdefinedinEquation2.
ThecurrentflowingoutoftheMONxpinisconvertedtoavoltagebyRMONxwhichistypically6.
81kΩ.
AnycircuitryconnectedtotheMONxpinshouldeitherhaveaninputimpedancemuchhigherthatRMONxtoreducemeasurementandlimitingerror,orthevalueoftheparallelcombinationmustbeadjusted.
TheoutputoftheMONxpincanalsobebufferedusingaunitygain,non-invertingoperationalamplifierifnecessary.
LAYOUTCONSIDERATIONSTPS2456Aapplicationsrequirelayoutattentiontoensureproperperformanceandminimizesusceptibilitytotransientsandnoise.
Ingeneral,allrunsshouldbeasshortaspossible,butthefollowinglistdeservesfirstconsideration.
1.
Whenused,decouplingcapacitorsonINAandINBshouldhaveminimallengthtothepinandtoGND2.
SENMxandSENPxrunsmustbeshortandrunside-by-sidetomaximizecommonmoderejection.
KelvinconnectionsshouldbeusedatthepointsofcontactwithRSENSEx.
(SeeFigure25)Figure25.
RecommendedRSENSELayout3.
SETxrunsneedtobeshortonbothsidesofRSETx.
4.
Powerpathconnectionsshouldbeasshortaspossibleandsizedtocarryatleasttwicethefullloadcurrent,moreifpossible.
24Copyright2012,TexasInstrumentsIncorporatedTPS2456Awww.
ti.
com.
cnZHCS998–JULY20125.
ConnectionstoGNDandMONxpinsshouldbeminimizedaftertheconnectionsabovehavebeenplaced.
6.
Thedevicedissipateslowpowersosolderingthepowerpadtotheboardisnotarequirement.
However,doingsoimprovesthermalperformanceandreducessusceptibilitytonoise.
7.
Theboardshoulduseasinglepointgroundscheme.
Thecurrentreturnpathforbothchannelsshouldbeisolatedfromeachotherasmuchaspossibleandtietogetheratasinglepoint.
Thishelpstoreducegroundbounceandfalseturnoffsinonechannelwhenthereisafaultintheotherchannel.
Also,sensitiveanaloggrounds(suchasthegroundconnectionsofRMONxandCTx)shouldberunseparatefromthepowerpathgrounds.
Thisanaloggroundmustalsotietothetwopowerpathgroundsatasinglepoint.
Figure26showsthetoplayerroutingoftheTPS2456AEVMwhichusesasinglepointgroundscheme.
Eachmajorpowerpath,theanalogground,andthesinglepointtyingthemtogetherishighlightedinthefigure.
Figure26.
8.
Protectiondevicessuchassnubbers,TVS,capacitorsordiodesshouldbeplacedphysicallyclosetothedevicetheyareintendedtoprotect,androutedwithshorttrancestoreduceinductance.
Forexample,theprotectionSchottkydiodeshowninFigure1shouldbephysicallyclosetothesourceofthepasstransistor(orthedrainoftheblockingMOSFETifused).
Copyright2012,TexasInstrumentsIncorporated25PACKAGEOPTIONADDENDUMwww.
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com6-Feb-2020Addendum-Page1PACKAGINGINFORMATIONOrderableDeviceStatus(1)PackageTypePackageDrawingPinsPackageQtyEcoPlan(2)Lead/BallFinish(6)MSLPeakTemp(3)OpTemp(°C)DeviceMarking(4/5)SamplesTPS2456ARHHRACTIVEVQFNRHH362500Green(RoHS&noSb/Br)NIPDAULevel-3-260C-168HR-40to852456ATPS2456ARHHTACTIVEVQFNRHH36250Green(RoHS&noSb/Br)NIPDAULevel-3-260C-168HR-40to852456A(1)Themarketingstatusvaluesaredefinedasfollows:ACTIVE:Productdevicerecommendedfornewdesigns.
LIFEBUY:TIhasannouncedthatthedevicewillbediscontinued,andalifetime-buyperiodisineffect.
NRND:Notrecommendedfornewdesigns.
Deviceisinproductiontosupportexistingcustomers,butTIdoesnotrecommendusingthispartinanewdesign.
PREVIEW:Devicehasbeenannouncedbutisnotinproduction.
Samplesmayormaynotbeavailable.
OBSOLETE:TIhasdiscontinuedtheproductionofthedevice.
(2)RoHS:TIdefines"RoHS"tomeansemiconductorproductsthatarecompliantwiththecurrentEURoHSrequirementsforall10RoHSsubstances,includingtherequirementthatRoHSsubstancedonotexceed0.
1%byweightinhomogeneousmaterials.
Wheredesignedtobesolderedathightemperatures,"RoHS"productsaresuitableforuseinspecifiedlead-freeprocesses.
TImayreferencethesetypesofproductsas"Pb-Free".
RoHSExempt:TIdefines"RoHSExempt"tomeanproductsthatcontainleadbutarecompliantwithEURoHSpursuanttoaspecificEURoHSexemption.
Green:TIdefines"Green"tomeanthecontentofChlorine(Cl)andBromine(Br)basedflameretardantsmeetJS709Blowhalogenrequirementsof<=1000ppmthreshold.
Antimonytrioxidebasedflameretardantsmustalsomeetthe<=1000ppmthresholdrequirement.
(3)MSL,PeakTemp.
-TheMoistureSensitivityLevelratingaccordingtotheJEDECindustrystandardclassifications,andpeaksoldertemperature.
(4)Theremaybeadditionalmarking,whichrelatestothelogo,thelottracecodeinformation,ortheenvironmentalcategoryonthedevice.
(5)MultipleDeviceMarkingswillbeinsideparentheses.
OnlyoneDeviceMarkingcontainedinparenthesesandseparatedbya"~"willappearonadevice.
IfalineisindentedthenitisacontinuationofthepreviouslineandthetwocombinedrepresenttheentireDeviceMarkingforthatdevice.
(6)Lead/BallFinish-OrderableDevicesmayhavemultiplematerialfinishoptions.
Finishoptionsareseparatedbyaverticalruledline.
Lead/BallFinishvaluesmaywraptotwolinesifthefinishvalueexceedsthemaximumcolumnwidth.
ImportantInformationandDisclaimer:TheinformationprovidedonthispagerepresentsTI'sknowledgeandbeliefasofthedatethatitisprovided.
TIbasesitsknowledgeandbeliefoninformationprovidedbythirdparties,andmakesnorepresentationorwarrantyastotheaccuracyofsuchinformation.
Effortsareunderwaytobetterintegrateinformationfromthirdparties.
TIhastakenandcontinuestotakereasonablestepstoproviderepresentativeandaccurateinformationbutmaynothaveconducteddestructivetestingorchemicalanalysisonincomingmaterialsandchemicals.
TIandTIsuppliersconsidercertaininformationtobeproprietary,andthusCASnumbersandotherlimitedinformationmaynotbeavailableforrelease.
InnoeventshallTI'sliabilityarisingoutofsuchinformationexceedthetotalpurchasepriceoftheTIpart(s)atissueinthisdocumentsoldbyTItoCustomeronanannualbasis.
PACKAGEOPTIONADDENDUMwww.
ti.
com6-Feb-2020Addendum-Page2www.
ti.
comGENERICPACKAGEVIEWThisimageisarepresentationofthepackagefamily,actualpackagemayvary.
Refertotheproductdatasheetforpackagedetails.
VQFN-1mmmaxheightRHH36PLASTICQUADFLATPACK-NOLEAD6x6,0.
5mmpitch4225440/Awww.
ti.
comPACKAGEOUTLINE6.
15.
96.
15.
91.
00.
80.
050.
002X432X0.
52X436X0.
650.
4536X0.
300.
184.
10.
1(0.
2)TYPVQFN-1mmmaxheightRHH0036BPLASTICQUADFLATPACK-NOLEAD4225414/A10/20190.
08C0.
1CAB0.
05NOTES:1.
Alllineardimensionsareinmillimeters.
Anydimensionsinparenthesisareforreferenceonly.
DimensioningandtolerancingperASMEY14.
5M.
2.
Thisdrawingissubjecttochangewithoutnotice.
3.
Thepackagethermalpadmustbesolderedtotheprintedcircuitboardforthermalandmechanicalperformance.
PIN1INDEXAREASEATINGPLANEPIN1IDSYMMEXPOSEDTHERMALPADSYMM1910181927283637SCALE2.
300ABCwww.
ti.
comEXAMPLEBOARDLAYOUT32X(0.
5)(R0.
05)TYP0.
07MAXALLAROUND0.
07MINALLAROUND36X(0.
75)36X(0.
24)(5.
65)(5.
65)(4.
1)(0.
2)TYPVIA(0.
68)TYP(1.
8)TYP(0.
68)TYP(1.
8)TYPVQFN-1mmmaxheightRHH0036BPLASTICQUADFLATPACK-NOLEAD4225414/A10/2019NOTES:(continued)4.
Thispackageisdesignedtobesolderedtoathermalpadontheboard.
Formoreinformation,seeTexasInstrumentsliteraturenumberSLUA271(www.
ti.
com/lit/slua271).
5.
Viasareoptionaldependingonapplication,refertodevicedatasheet.
Ifanyviasareimplemented,refertotheirlocationsshownonthisview.
Itisrecommendedthatviasunderpastebefilled,pluggedortented.
SYMMSYMMLANDPATTERNEXAMPLEEXPOSEDMETALSHOWNSCALE:15XSEESOLDERMASKDETAIL1910181927283637METALEDGESOLDERMASKOPENINGEXPOSEDMETALMETALUNDERSOLDERMASKSOLDERMASKOPENINGEXPOSEDMETALNONSOLDERMASKDEFINED(PREFERRED)SOLDERMASKDEFINEDSOLDERMASKDETAILSwww.
ti.
comEXAMPLESTENCILDESIGN36X(0.
75)36X(0.
24)32X(0.
5)(5.
65)(5.
65)9X(1.
16)(R0.
05)TYP(1.
36)TYP(1.
36)TYPVQFN-1mmmaxheightRHH0036BPLASTICQUADFLATPACK-NOLEAD4225414/A10/2019NOTES:(continued)6.
Lasercuttingapertureswithtrapezoidalwallsandroundedcornersmayofferbetterpasterelease.
IPC-7525mayhavealternatedesignrecommendations.
SOLDERPASTEEXAMPLEBASEDON0.
125MMTHICKSTENCILSCALE:15XEXPOSEDPAD3772%PRINTEDSOLDERCOVERAGEBYAREAUNDERPACKAGESYMMSYMM1910181927283637重重要要声声明明和和免免责责声声明明TI均以"原样"提供技术性及可靠性数据(包括数据表)、设计资源(包括参考设计)、应用或其他设计建议、网络工具、安全信息和其他资源,不保证其中不含任何瑕疵,且不做任何明示或暗示的担保,包括但不限于对适销性、适合某特定用途或不侵犯任何第三方知识产权的暗示担保.
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