capacitorwww.fefe66.com

TPS54386-Q1www.
ti.
comSLUSAZ9A–MARCH2012–REVISEDMARCH20123-ADUALNON-SYNCHRONOUSCONVERTERWITHINTEGRATEDHIGH-SIDEMOSFETCheckforSamples:TPS54386-Q11FEATURESAPPLICATIONS23QualifiedforAutomotiveApplicationsPowerforDSPAEC-Q100QualifiedWiththeFollowingConsumerElectronicsResults:CONTENTS–DeviceTemperatureGrade2:–40°CtoDeviceRatings2+105°CAmbientOperatingTemperatureElectricalCharacteristics3–DeviceHBMESDClassificationLevelH2DeviceInformation9–DeviceCDMESDClassificationLevelC3BApplicationInformation124.
5-Vto28-VInputRangeDesignExamples32OutputVoltageRange0.
8Vto90%ofInputAdditionalReferences44VoltageOutputCurrentUpto3ADESCRIPTIONFixedSwitchingFrequency:600kHzTheTPS54386-Q1aredual-output,non-synchronousThreeSelectableLevelsofOvercurrentbuckconverterscapableofsupporting3-Aoutputapplicationsthatoperatefroma4.
5-Vto28-VinputProtection(Output2)supplyvoltage,andrequireoutputvoltagesbetween0.
8-V1.
5%VoltageReference0.
8Vand90%oftheinputvoltage.
2.
1-msInternalSoftStartWithaninternally-determinedoperatingfrequency,DualPWMOutputs180°Out-of-Phasesoft-starttime,andcontrol-loopcompensation,theseRatiometricorSequentialStartupModesconvertersprovidemanyfeatureswithaminimumofSelectablebyaSinglePinexternalcomponents.
Channel-1overcurrentprotectionissetat4.
5A,whereasthechannel-285-mInternalHigh-SideMOSFETsovercurrentprotectionlevelisselectedbyconnectingCurrentModeControlapintoground,toBP,orleftfloating.
ThesettingInternalCompensationlevelsareusedtoallowforscalingofexternalcomponentsforapplicationsthatdonotneedthefullPulse-by-PulseOvercurrentProtectionloadcapabilityofbothoutputs.
ThermalShutdownProtectionat148°CTheoutputsmaybeenabledindependently,ormay14-PinPowerPADHTSSOPPackagebeconfiguredtoalloweitherratiometricorsequentialstart-upsequencing.
Additionally,thetwooutputsmaybepoweredfromdifferentsources.
1Pleasebeawarethatanimportantnoticeconcerningavailability,standardwarranty,anduseincriticalapplicationsofTexasInstrumentssemiconductorproductsanddisclaimerstheretoappearsattheendofthisdatasheet.
2PowerPADisatrademarkofTexasInstruments.
3Allothertrademarksarethepropertyoftheirrespectiveowners.
PRODUCTIONDATAinformationiscurrentasofpublicationdate.
Copyright2012,TexasInstrumentsIncorporatedProductsconformtospecificationsperthetermsoftheTexasInstrumentsstandardwarranty.
Productionprocessingdoesnotnecessarilyincludetestingofallparameters.
TPS54386-Q1SLUSAZ9A–MARCH2012–REVISEDMARCH2012www.
ti.
comThesedeviceshavelimitedbuilt-inESDprotection.
TheleadsshouldbeshortedtogetherorthedeviceplacedinconductivefoamduringstorageorhandlingtopreventelectrostaticdamagetotheMOSgates.
Table1.
ORDERINGINFORMATION(1)PARTNUMBEROPERATINGFREQUENCY(kHz)PACKAGEMEDIAUNITSTOP-SIDEMARKINGTPS54386TPWPRQ160014-HTSSOPpackageTapeandreel200054386T(1)ForthemostcurrentpackageandorderinginformationseethePackageOptionAddendumattheendofthisdocument,orseetheTIwebsiteatwww.
ti.
com.
DEVICERATINGSABSOLUTEMAXIMUMRATINGS(1)VALUEUNITPVDD1,PVDD2,EN1,EN230BOOT1,BOOT2VSW+7SW1,SW2–2to30InputvoltagerangeSW1,SW2transient(1A(4)100200nsDMINMinimumdutycycleVFB=0.
9V0%DMAXMaximumdutycyclefSW=600kHz85%90%ISWSwitching-nodeleakagecurrent(sourcing)OutputsOFF212μATHERMALSHUTDOWNTSD(3)Shutdowntemperature148°CTSD(hys)(3)Hysteresis20°C(3)Ensuredbydesign.
Notproductiontested.
(4)SeeFigure14forISWxpeakcurrentBPSequential,output2thenoutput1ActiveenablethresholdvoltageTieEN1to>enablethresholdvoltageforlowquiescentcurrent(BPinactive)whenVEN2>enablethresholdvoltageIgnoredbythedevice.
whenVEN1GNDSequential,output1thenoutput2ActiveenablethresholdvoltageTieEN2to>enablethresholdvoltageforlowquiescentcurrent(BPinactive)whenVEN1>enablethresholdvoltageIndependentorratiometric,output1Active.
EN1andEN2mustbetiedActive.
EN1andEN2mustbetied(floating)andoutput2togetherforRatio-metricstartup.
togetherforratiometricstart-up.
IftheSEQpinisconnectedtoBP,thenwhenoutput2isenabled,output1isallowedtostartapproximately400μsafteroutput2hasreachedregulation;thatis,sequentialstart-upwhereoutput1isslavetooutput2.
IfEN2isallowedtogohighaftertheoutputshavebeenoperating,thenbothoutputsaredisabledimmediately,andtheoutputvoltagesdecayaccordingtotheloadthatispresent.
IftheSEQpinisconnectedtoGND,thenwhenoutput1isenabled,output2isallowedtostartapproximately400μsafteroutput1hasreachedregulation;thatis,sequentialstart-upwhereoutput2isslavetooutput1.
IfEN1isallowedtogohighaftertheoutputshavebeenoperating,thenbothoutputsaredisabledimmediately,andtheoutputvoltagesdecayaccordingtotheloadthatispresent.
Figure18.
SEQPinTiedtoBPFigure19.
SEQPinTiedtoGNDNOTEAnR-CnetworkconnectedtotheENxpinmaybeusedinadditiontotheSEQpininsequentialmodetodelaythestart-upofthefirstoutputvoltage.
Thisapproachmaybenecessaryinsystemswithalargenumberofoutputvoltagesandelaboratevoltage-sequencingrequirements.
SeeEnableandTimedTurnOnoftheOutputs.
14SubmitDocumentationFeedbackCopyright2012,TexasInstrumentsIncorporatedProductFolderLink(s):TPS54386-Q1TPS54386-Q1www.
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comSLUSAZ9A–MARCH2012–REVISEDMARCH2012IftheSEQpinisleftfloating,output1andoutput2eachstartratiometricallywhenbothoutputsareenabledatthesametime.
Output1andoutput2soft-startataratethatisdeterminedbytherespectivefinaloutputvoltagesandenterregulationatthesametime.
IftheEN1andEN2pinsareallowedtooperateindependently,thenthetwooutputsalsooperateindependently.
Figure20.
SEQPinFloatingSoftStartEachoutputhasadedicatedsoft-startcircuit.
Thesoft-startvoltageisaninternaldigitalreferenceramptooneoftwononinvertinginputsoftheerroramplifier.
Theotherinputisthe(internal)precision0.
8-Vreference.
ThetotalramptimefortheFBvoltagetochargefrom0Vto0.
8Visabout2.
1ms.
Duringasoft-startinterval,theTPS54386-Q1outputslowlyincreasesthevoltagetothenoninvertinginputoftheerroramplifier.
Inthisway,theoutputvoltagerampsupslowlyuntilthevoltageonthenoninvertinginputtotheerroramplifierreachestheinternal0.
8-Vreferencevoltage.
Atthattime,thevoltageatthenoninvertinginputtotheerroramplifierremainsatthereferencevoltage.
NOTEToavoidadisturbanceintheoutputvoltageduringthesteppingofthedigitalsoft-start,aminimumoutputcapacitanceof50μFisrecommended.
SeeFeedbackLoopandInductor-Capacitor(L-C)FilterSelection.
Oncethefilterandcompensationcomponentshavebeenestablished,laboratorymeasurementsofthephysicaldesignshouldbeperformedtoconfirmconverterstability.
Duringthesoft-startinterval,pulse-by-pulsecurrentlimitingisineffect.
Ifanovercurrentpulseisdetected,sixPWMpulsesareskippedtoallowtheinductorcurrenttodecaybeforeanotherPWMpulseisapplied.
(SeetheOutputOverloadProtectionsection.
)Thereisnopulse-skippingifacurrent-limitpulseisnotdetected.
DESIGNHINTIftherateofriseoftheinputvoltage(PVDDx)issuchthattheinputvoltageistoolowtosupportthedesiredregulationvoltagebythetimesoft-starthascompleted,thentheoutputUVcircuitmaytripandcauseahiccupintheoutputvoltage.
Inthiscase,useatimed-delaystart-upfromtheENxpintodelaythestart-upoftheoutputuntilthePVDDxvoltagehasthecapabilityofsupportingthedesiredregulationvoltage.
SeeOperatingNearMaximumDutyCycleandMaximumOutputCapacitanceforrelatedinformation.
Copyright2012,TexasInstrumentsIncorporatedSubmitDocumentationFeedback15ProductFolderLink(s):TPS54386-Q1TPS54386-Q1SLUSAZ9A–MARCH2012–REVISEDMARCH2012www.
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comOutputVoltageRegulationEachoutputhasadedicatedfeedbackloopcomprisingavoltage-settingdivider,anerroramplifier,apulse-widthmodulator,andaswitchingMOSFET.
Theregulationoutputvoltageisdeterminedbyaresistordividerconnectingtheoutputnode,theFBxpin,andGND(seeFigure21).
Assumingthevalueoftheupperresistorofthevoltage-settingdividerisknown,thevalueofthelowerdividerresistorforadesiredoutputvoltageiscalculatedbyEquation2.
whereVREFistheinternal0.
8-Vreferencevoltage.
(2)Figure21.
FeedbackNetworkforChannel1DESIGNHINTThereisaleakagecurrentofupto12μAoutoftheSWpinwhenasingleoutputoftheTPS54386-Q1isdisabled.
KeepingtheseriesimpedanceofR1+R2lessthan50kpreventstheoutputfromfloatingabovethereferencevoltagewhilethecontrolleroutputisintheOFFstate.
16SubmitDocumentationFeedbackCopyright2012,TexasInstrumentsIncorporatedProductFolderLink(s):TPS54386-Q1TPS54386-Q1www.
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comSLUSAZ9A–MARCH2012–REVISEDMARCH2012FeedbackLoopandInductor-Capacitor(L-C)FilterSelectionInthefeedbacksignalpath,theoutputvoltage-settingdividerisfollowedbyaninternalgM-typeerroramplifierwithatypicaltransconductanceof30μs.
Aninternalseries-connectedR-CcircuitfromthegMamplifieroutputtogroundservesasthecompensationnetworkfortheconverter.
ThesignalfromtheerroramplifieroutputisthenbufferedandcombinedwithaslopecompensationsignalbeforeitismirroredtobereferencedtotheSWnode.
Here,itiscomparedwiththecurrentfeedbacksignaltocreateapulse-width-modulated(PWM)signaltodrivetheupperMOSFETswitch.
AsimplifiedequivalentcircuitofthesignalcontrolpathisdepictedinFigure22.
NOTENoisecouplingfromtheSWxnodetointernalcircuitryofBOOTxmayimpactnarrowpulse-widthoperation,especiallyatloadcurrentslessthan1A.
SeeSWNodeRingingforfurtherinformationonreducingnoiseontheSWxnode.
Figure22.
Feedback-LoopEquivalentCircuitAmoreconventionalsmall-signalequivalentblockdiagramisshowninFigure23.
Here,thefullclosed-loopsignalpathisshown.
BecausetheTPS54386-Q1containsinternalslope-compensationandloop-compensationcomponents,theexternalL-Cfiltermustbeselectedappropriatelysothattheresultingcontrolloopmeetscriteriaforstability.
Thisapproachdiffersfromanexternally-compensatedcontroller,wheretheL-Cfilterisgenerallyselectedfirst,andthecompensationnetworkisfoundafterwards.
TofindtheappropriateLandCfiltercombination,theoutput-to-Vcsignalpathplots(seethenextsection)ofgainandphaseareusedalongwithotherdesigncriteriatoaidinfindingthecombinationthatbestresultsinastablefeedbackloop.
Copyright2012,TexasInstrumentsIncorporatedSubmitDocumentationFeedback17ProductFolderLink(s):TPS54386-Q1TPS54386-Q1SLUSAZ9A–MARCH2012–REVISEDMARCH2012www.
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comFigure23.
Small-SignalEquivalentBlockDiagramInductor-Capacitor(L-C)SelectionThefollowingfiguresplottheTPS54386-Q1output-to-Vcgainandphaseversusfrequencyforvariousdutycycles(10%,30%,50%,70%,90%)atthree(200mA,400mA,600mA)peak-to-peakripple-currentlevels.
Theloopresponsecurveselectedtocompensatetheloopisbasedonthedutycycleoftheapplicationandtheripplecurrentintheinductor.
Oncethecurvehasbeenselectedandtheinductorvaluehasbeencalculated,theoutputcapacitorisfoundbycalculatingtheL-Cresonantfrequencyrequiredtocompensatethefeedbackloop.
Abriefexamplefollowsthecurves.
Notethattheinternalerror-amplifiercompensationisoptimizedforoutputcapacitorswithanESRzerofrequencybetween20kHzand60kHz.
Seethefollowingsectionsforfurtherdetails.
GAINANDPHASEGAINANDPHASEvsvsFREQUENCYFREQUENCYFigure24.
TPS54386-Q1at200-mAppRippleFigure25.
TPS54386-Q1at400-mAppRippleCurrentCurrent18SubmitDocumentationFeedbackCopyright2012,TexasInstrumentsIncorporatedProductFolderLink(s):TPS54386-Q1TPS54386-Q1www.
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comSLUSAZ9A–MARCH2012–REVISEDMARCH2012GAINANDPHASEvsFREQUENCYFigure26.
TPS54386-Q1at600-mAppRippleCurrentMaximumOutputCapacitanceWithinternalpulse-by-pulsecurrentlimitingandafixedsoft-starttime,thereisamaximumoutputcapacitancewhichmaybeusedbeforestart-upproblemsbegintooccur.
Iftheoutputcapacitanceislargeenoughsothatthedeviceentersacurrent-limitprotectionmodeduringstartup,thenthereisapossibilitythattheoutputwillneverreachregulation.
Instead,theTPS54386-Q1simplyshutsdownandattemptsarestartasiftheoutputwereshort-circuitedtoground.
Themaximumoutputcapacitance(includingbypasscapacitancedistributedattheload)isgivenbyEquation3:(3)MinimumOutputCapacitanceEnsurethevalueofcapacitanceselectedforclosed-loopstabilityiscompatiblewiththerequirementsofSoftStart.
ModifyingTheFeedbackLoopWithinthelimitsoftheinternalcompensation,thereisflexibilityintheselectionoftheinductorandoutput-capacitorvalues.
Asmallerinductorincreasesripplecurrent,andraisestheresonantfrequency,therebyincerasingtherequiredamountofoutputcapacitance.
Asmallercapacitorcouldalsobeused,increasingtheresonantfrequency,andincreasingtheoverallloopbandwidth—perhapsattheexpenseofadequatephasemargin.
TheinternalcompensationoftheTPS54x8xisdesignedforcapacitorswithanESRzerofrequencybetween20kHzand60kHz.
Itispossible,withadditionalfeedbackcompensationcomponents,tousecapacitorswithhigherorlowerESRzerofrequencies.
Foreithercase,thecomponentsC1andR3(seeFigure30)areaddedtore-compensatethefeedbackloopforstability.
Inthisconfiguration,alowfrequencypoleisfollowedbyahigher-frequencyzero.
Theplacementofthispole-zeropairisdependentonthetypeofoutputcapacitorusedandthedesiredclosed-loopfrequencyresponse.
Copyright2012,TexasInstrumentsIncorporatedSubmitDocumentationFeedback19ProductFolderLink(s):TPS54386-Q1TPS54386-Q1SLUSAZ9A–MARCH2012–REVISEDMARCH2012www.
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comFigure27.
OptionalLoopCompensationComponentsNOTEOncethefilterandcompensationcomponentshavebeenestablished,laboratorymeasurementsofthephysicaldesignshouldbeperformedtoconfirmconverterstability.
UsingHigh-ESROutputCapacitorsIfahigh-ESRcapacitorisusedintheoutputfilter,azeroappearsintheloopresponsethatcouldleadtoinstability.
Tocompensate,asmallR-Cseriesconnectednetworkisplacedinparallelwiththelowervoltage-settingdividerresistor(seeFigure27).
ThevaluesofthecomponentsaredeterminedsuchthatapoleisplacedatthesamefrequencyastheESRzeroandanewzeroisplacedatafrequencylocationconducivetogoodloopstability.
ThevalueoftheresistoriscalculatedusingaratioofimpedancestomatchtheratioofESRzerofrequencytothedesiredzerofrequency.
where:fESR(zero)istheESRzerofrequencyoftheoutputcapacitor.
fZERO(desired)isthedesiredfrequencyofthezeroaddedtothefeedback.
Thisfrequencyshouldbeplacedbetween20kHzand60kHztoensuregoodloopstability.
(4)20SubmitDocumentationFeedbackCopyright2012,TexasInstrumentsIncorporatedProductFolderLink(s):TPS54386-Q1TPS54386-Q1www.
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comSLUSAZ9A–MARCH2012–REVISEDMARCH2012ThevalueofthecapacitoriscalculatedinEquation5.
where:REQisanequivalentimpedancecreatedbytheparallelcombinationofthevoltage-settingdividerresistors(R1andR2)inserieswithR3.
(5)(6)UsingAllCeramicOutputCapacitorsWithlow-ESRceramiccapacitors,theremaynotbeenoughphasemarginatthecrossoverfrequency.
Inthiscase(seeFigure27),resistorR3issetequalto1/2R2.
Thislowersthegainby6dB,reducesthecrossoverfrequency,andimprovesphasemargin.
ThevalueofC1isfoundbydeterminingthefrequencyatwhichtoplacethelow-frequencypole.
Theminimumfrequencyatwhichtoplacethepoleis1kHz.
Anylower,andthetimeconstantwillbetooslowandinterferewiththeinternalsoft-start(seeSoftStart).
Theupperboundforthepolefrequencyisdeterminedbytheoperatingfrequencyoftheconverter.
Itis3kHzfortheTPS54x83,and6kHzfortheTPS54x86.
C1isthenfoundfromEquation7.
Keepcomponenttolerancesinmindwhenselectingthedesiredpolefrequency.
where:fPOLE(desired)isthedesiredpolefrequencybetween1kHzand3kHz(TPS54x83)or1kHzand6kHz(TPS54x86).
REQisanequivalentimpedancecreatedbytheparallelcombinationofthevoltage-settingdividerresistors(R1andR2)inserieswithR3.
(7)(8)Ifitisnecessarytoincreasephasemargin,placeacapacitorinparallelwiththeuppervoltage-settingdividerresistor(C2inEquation9).
wherefCistheunity-gaincrossoverfrequency,(approximately50kHzformostdesignsfollowingtheseguidelines).
(9)Copyright2012,TexasInstrumentsIncorporatedSubmitDocumentationFeedback21ProductFolderLink(s):TPS54386-Q1TPS54386-Q1SLUSAZ9A–MARCH2012–REVISEDMARCH2012www.
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comExample:TPS54386-Q1BuckConverterOperatingat12-VInput,3.
3-VOutputand400-mA(P-P)RippleCurrentFirst,thesteady-statedutycycleiscalculated.
Assumingtherectifierdiodehasavoltagedropof0.
5V,thedutycycleisapproximatedusingEquation10.
(10)Thefilterinductoristhencalculated;seeEquation11.
(11)Acustom-designedinductormaybeusedfortheapplication,orastandardvalueclosetothecalculatedvaluemaybeused.
Forthisexample,astandard10-μHinductorisused.
UsingFigure25,findthe30%dutycyclecurve.
The30%dutycyclecurvehasadownslopefromlowfrequencyandrisesatapproximately6kHz.
Thiscurveistheresonantfrequencythatmustbecompensated.
Anyfrequencywithinanoctaveofthepeakmaybeusedincalculatingthecapacitorvalue.
Inthisexample,6kHzisused.
(12)A68-μFcapacitorshouldbeusedasabulkcapacitor,withupto10μFofceramicbypasscapacitance.
ToensuretheESRzerodoesnotsignificantlyimpacttheloopresponse,theESRofthebulkcapacitorshouldbeplacedadecadeabovetheresonantfrequency.
(13)TheresultingloopgainandphaseareshowninFigure28.
Basedonmeasurement,loopcrossoveris45kHzwithaphasemarginof60degrees.
GAINANDPHASEvsFREQUENCYFigure28.
ExampleLoopResult22SubmitDocumentationFeedbackCopyright2012,TexasInstrumentsIncorporatedProductFolderLink(s):TPS54386-Q1TPS54386-Q1www.
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comSLUSAZ9A–MARCH2012–REVISEDMARCH2012BootstrapfortheN-ChannelMOSFETAbootstrapcircuitprovidesavoltagesourcehigherthantheinputvoltageandofsufficientenergytofullyenhancetheswitchingMOSFETeachswitchingcycle.
ThePWMdutycycleislimitedtoamaximumof90%,allowinganexternalbootstrapcapacitortochargethroughaninternalsynchronousswitch(betweenBPandBOOTx)duringeverycycle.
WhenthePWMswitchiscommandedtoturnON,theenergyusedtodrivetheMOSFETgateisderivedfromthevoltageonthiscapacitor.
Toallowthebootstrapcapacitortochargeeachswitchingcycle,aninternalpulldownMOSFET(fromSWtoGND)isturnedONforapproximately140nsatthebeginningofeachswitchingcycle.
Inthisway,if,duringlightloadoperation,thereisinsufficientenergyfortheSWnodetodrivetogroundnaturally,thisMOSFETforcestheSWnodetowardgroundandallowsthebootstrapcapacitortocharge.
Becausethisisachargetransfercircuit,caremustbetakeninselectingthevalueofthebootstrapcapacitor.
Itmustbesizedsuchthattheenergystoredinthecapacitoronaper-cyclebasisisgreaterthanthegatechargerequirementoftheMOSFETbeingused.
DESIGNHINTForthebootstrapcapacitor,useaceramiccapacitorwithavaluebetween22nFand82nF.
NOTEFor5-Vinputapplications,connectPVDDxtoBPdirectly.
Thisconnectionbypassestheinternalcontrol-circuitregulatorandprovidesmaximumvoltagetothegate-drivecircuitry.
Inthisconfiguration,shutdownmodeIDDSDNisthesameasquiescentIDDQ.
LightLoadOperationThereisnospecialcircuitryforpulseskippingatlightloads.
Thenormalcharacteristicofanonsynchronousconverteristooperateinthediscontinuous-conductionmode(DCM)atanaverageloadcurrentlessthanone-halfoftheinductorpeak-to-peakripplecurrent.
Notethattheamplitudeoftheripplecurrentisafunctionofinputvoltage,outputvoltage,inductorvalue,andoperatingfrequency,asshowninEquation14.
(14)Further,duringdiscontinuous-modeoperationthecommandedpulsedurationmaybecomenarrowerthanthecapabilityoftheconvertertoresolve.
Tomaintaintheoutputvoltagewithinregulation,skippingswitchingpulsesatlightloadconditionsisanaturalbyproductofthatmode.
Thisconditionmayoccuriftheoutputcapacitorischargedtoavaluegreaterthantheoutputregulationvoltageandthereisinsufficientloadtodischargethecapacitor.
Abyproductofpulseskippingisanincreaseinthepeak-to-peakoutputripplevoltage.
Copyright2012,TexasInstrumentsIncorporatedSubmitDocumentationFeedback23ProductFolderLink(s):TPS54386-Q1TPS54386-Q1SLUSAZ9A–MARCH2012–REVISEDMARCH2012www.
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comFigure29.
SteadyStateFigure30.
SkippingDESIGNHINTIfadditionaloutputcapacitanceisrequiredtoreducetheoutput-voltagerippleduringDCMoperation,besuretorechecktheFeedbackLoopandInductor-Capacitor(L-C)FilterSelectionandMaximumOutputCapacitancesections.
SWNodeRingingAportionofthecontrolcircuitryisreferencedtotheSWnode.
Toensurejitter-freeoperation,itisnecessarytodecreasethevoltagewaveformringingattheSWnodetolessthan5voltspeakandofadurationoflessthan30-ns.
Inadditiontofollowinggoodprinted-circuitboard(PCB)layoutpractices,thereareacoupleofdesigntechniquesforreducingringingandnoise.
SWNodeSnubberVoltageringingobservableattheSWnodeiscausedbyfastswitchingedgesandparasiticinductanceandcapacitance.
IftheringingresultsinexcessivevoltageontheSWnode,orerraticoperationoftheconverter,anR-Csnubbermaybeusedtodampentheringingandensureproperoperationoverthefullloadrange.
DESIGNHINTAseries-connectedR-Csnubber(C=between330pFand1nF,R=10)connectedfromSWtoGNDreducestheringingontheSWnode.
BootstrapResistorAsmallresistorinserieswiththebootstrapcapacitorreducestheturnontimeoftheinternalMOSFET,therebyreducingtherising-edgeringingoftheSWnode.
DESIGNHINTAresistorwithavaluebetween1and3maybeplacedinserieswiththebootstrapcapacitortoreduceringingontheSWnode.
DESIGNHINTPlaceholdersforthesecomponentsshouldbeplacedontheinitialprototypePCBsincasetheyareneeded.
24SubmitDocumentationFeedbackCopyright2012,TexasInstrumentsIncorporatedProductFolderLink(s):TPS54386-Q1TPS54386-Q1www.
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comSLUSAZ9A–MARCH2012–REVISEDMARCH2012OutputOverloadProtectionIntheeventofanovercurrentduringsoft-startoneitheroutput(suchasstartingintoanoutputshort),pulse-by-pulsecurrentlimitingandPWMfrequencydivisionareineffectforthatoutputuntiltheinternalsoft-starttimerends.
Attheendofthesoft-starttime,aUVconditionisdeclaredandafaultisdeclared.
Duringthisfaultcondition,bothPWMoutputsaredisabledandthesmallpulldownMOSFETs(fromSWxtoGND)areturnedON.
ThisprocessensuresthatbothoutputsdischargetoGNDintheeventthatovercurrentisononeoutputwhiletheotherisnotloaded.
Theconverterthenentersahiccup-modetime-outbeforeattemptingtorestart.
Frequencydivisionmeansifanovercurrentpulseisdetected,sixclockcyclesareskippedbeforethenextPWMpulseisinitiated,effectivelydividingtheoperatingfrequencybysixandpreventingexcessivecurrentbuildupintheinductor.
Intheeventofanovercurrentoneitheroutputaftertheoutputreachesregulation,pulse-by-pulsecurrentlimitisineffectforthatoutput.
Inaddition,anoutputundervoltage(UV)comparatormonitorstheFBxvoltage(thatfollowstheoutputvoltage)todeclareafaultiftheoutputdropsbelow85%ofregulation.
Duringthisfaultcondition,bothPWMoutputsaredisabledandthesmallpulldownMOSFETs(fromSWxtoGND)areturnedON.
ThisdesignensuresthatbothoutputsdischargetoGND,intheeventthatovercurrentisononeoutputwhiletheotherisnotloaded.
Theconverterthenentersahiccup-modetimeoutbeforeattemptingtorestart.
Theovercurrentthresholdforoutput1issetnominallyat4.
5A.
Theovercurrentlevelofoutput2isdeterminedbythestateoftheILIM2pin.
TheILIMsettingofoutput2isnotlatchedinplaceandmaybechangedduringoperationoftheconverter.
Table3.
CurrentLimitThresholdAdjustmentforOutput2ILIM2ConnectionOCPThresholdforOutput2BP4.
5-Anominalsetting(floating)3-AnominalsettingGND1.
5-AnominalsettingDESIGNHINTTheOCPthresholdreferstothepeakcurrentintheinternalswitch.
Besuretoaddone-halfofthepeakinductorripplecurrenttothedcloadcurrentindetermininghowclosetheactualoperatingpointistotheOCPthreshold.
OperatingNearMaximumDutyCycleIftheTPS54386-Q1operatesatmaximumdutycycle,andiftheinputvoltageisinsufficienttosupporttheoutputvoltage(atfullloadorduringaload-currenttransient),thenthereisapossibilitythattheoutputvoltagewillfallfromregulationandtriptheoutputUVcomparator.
Ifthisshouldoccur,theTPS54386-Q1protectioncircuitrydeclaresafaultandentersashut-down-and-restartcycle.
DESIGNHINTEnsurethatunderALLconditionsoflineandloadregulation,thereissufficientdutycycletomaintainoutput-voltageregulation.
Tocalculatetheoperatingdutycycle,useEquation15.
whereVDIODEisthevoltagedropoftherectifierdiode.
(15)Copyright2012,TexasInstrumentsIncorporatedSubmitDocumentationFeedback25ProductFolderLink(s):TPS54386-Q1TPS54386-Q1SLUSAZ9A–MARCH2012–REVISEDMARCH2012www.
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comDual-SupplyOperationItispossibletooperateaTPS54386-Q1fromtwosupplyvoltages.
Ifthisapplicationisdesired,thenthesequencingofthesuppliesmustbesuchthatPVDD2isabovetheUVLOvoltagebeforePVDD1beginstorise.
ThislevelrequirementensuresthattheinternalregulatorandthecontrolcircuitryareinoperationbeforePVDD1suppliesenergytotheoutput.
Inaddition,output1mustbeheldinthedisabledstate(EN1high)untilthereissufficientvoltageonPVDD1tosupportoutput1inregulation.
(SeetheOperatingNearMaximumDutyCyclesection.
)Thepreferredsequenceofeventsis:1.
PVDD2risesabovetheinputUVLOvoltage.
2.
PVDD1riseswithoutput1disableduntilPVDD1risesabovetheleveltosupportoutput1regulation.
Withthesetwoconditionssatisfied,thereisnorestrictiononPVDD2tobegreaterthanorlessthanPVDD1.
DESIGNHINTAnR-CdelayonEN1maybeusedtodelaythestart-upofoutput1foralong-enoughperiodoftimetoensurethatPVDD1cansupporttheoutput1load.
CascadingSupplyOperationItispossibletosourcePVDD1fromoutput2asdepictedinFigure31andFigure32.
Thisconfigurationmaybepreferrediftheinputvoltageishigh,relativetothevoltageonoutput1.
Figure31.
SchematicShowingCascadingPVDD1FromOutput226SubmitDocumentationFeedbackCopyright2012,TexasInstrumentsIncorporatedProductFolderLink(s):TPS54386-Q1TPS54386-Q1www.
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comSLUSAZ9A–MARCH2012–REVISEDMARCH2012Figure32.
WaveformsResultingFromCascadingPVDD1FromOutput2Inthisconfiguration,thefollowingconditionsmustbemaintained:1.
Output2mustbeofavoltagehighenoughtomaintainregulationofoutput1underallloadconditions.
2.
Thesumofthecurrentdrawnbyoutput2loadplusthecurrentintoPVDD1mustbelessthantheoverloadprotectioncurrentlevelofoutput2.
3.
Themethodofoutputsequencingmustbesuchthatthevoltageonoutput2issufficienttosupportoutput1beforeoutput1isenabled.
Thisrequrementmaybeaccomplishedby:(a)adelayoftheenablefunction(b)selectingsequentialsequencingofoutput1startingafteroutput2isinregulationMultiphaseOperationTheTPS54386-Q1isnotdesignedtooperateasatwo-channelmultiphaseconverter.
Seehttp://www.
power.
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comforappropriatedeviceselection.
BypassandFIlteringAswithanyintegratedcircuit,supplybypassingisimportantforjitter-freeoperation.
Toimprovethenoiseimmunityoftheconverter,ceramicbypasscapacitorsmustbeplacedasclosetothepackageaspossible.
1.
PVDD1toGND:Usea10-μFceramiccapacitor.
2.
PVDD2toGND:Usea10-μFceramiccapacitor.
3.
BPtoGND:Usea4.
7-μFto10-μFceramiccapacitor.
OvertemperatureProtectionandJunctionTemperatureRiseTheovertemperaturethermalprotectionlimitsthemaximumpowertobedissipatedatagivenoperatingambienttemperature.
Inotherwords,atagivendevicepowerdissipation,themaximumambientoperatingtemperatureislimitedbythemaximumallowablejunctionoperatingtemperature.
Thedevicejunctiontemperatureisafunctionofpowerdissipationandthethermalimpedancefromthejunctiontoambient.
Iftheinternaldietemperatureshouldreachthethermalshutdownlevel,theTPS54386-Q1shutsoffbothPWMsandremainsinthisstateuntilthedietemperaturedropsbelowthehysteresisvalue,atwhichtimethedevicerestarts.
Thefirststeptodeterminethedevicejunctiontemperatureistocalculatethepowerdissipation.
ThepowerdissipationisdominatedbythetwoswitchingMOSFETsandtheBPinternalregulator.
ThepowerdissipatedbyeachMOSFETiscomposedofconductionlossesandoutput(switching)lossesincurredwhiledrivingtheexternalrectifierdiode.
Tofindtheconductionloss,firstfindthermscurrentthroughtheupperswitchMOSFET.
Copyright2012,TexasInstrumentsIncorporatedSubmitDocumentationFeedback27ProductFolderLink(s):TPS54386-Q1TPS54386-Q1SLUSAZ9A–MARCH2012–REVISEDMARCH2012www.
ti.
comwhereDisthedutycycle.
IOUTPUTxisthedcoutputcurrent.
ΔIOUTPUTxisthepeakripplecurrentintheinductorforoutputx.
(16)Noticetheimpactoftheoperatingdutycycleontheresult.
MultiplyingtheresultbytheRDS(on)oftheMOSFETgivestheconductionloss.
(17)Theswitchinglossisapproximatedby:wherewhereCJistheparallelcapacitanceoftherectifierdiodeandsnubber(ifany).
fSistheswitchingfrequency.
(18)ThetotalpowerdissipationisfoundbysummingthepowerlossforbothMOSFETsplusthelossintheinternalregulator.
(19)Thetemperatureriseofthedevicejunctiondependsonthethermalimpedancefromthejunctiontothemountingpad(seethePackageDissipationRatingstable),plusthethermalimpedancefromthethermalpadtoambient.
ThethermalimpedancefromthethermalpadtoambientdependsonthePCBlayout(thermal-padinterfacetothePCB,theexposedpadarea)andairflow(ifany).
SeethePCBLayoutGuidelines,AdditionalReferencessection.
TheoperatingjunctiontemperatureisshowninEquation20.
(20)PowerDeratingTheTPS54386-Q1deliversfullcurrentatambienttemperaturesupto85°Cifthethermalimpedancefromthethermalpadmaintainsthejunctiontemperaturebelowthethermalshutdownlevel.
Athigherambienttemperatures,thedevicepowerdissipationmustbereducedtomaintainthejunctiontemperatureatorbelowthethermalshutdownlevel.
Figure33illustratesthepowerderatingforelevatedambienttemperatureundervariousairflowconditions.
Notethatthesecurvesassumethatthethermalpadisproperlysolderedtotherecommendedboard.
(SeetheReferencessectionforfurtherinformation.
)28SubmitDocumentationFeedbackCopyright2012,TexasInstrumentsIncorporatedProductFolderLink(s):TPS54386-Q1TPS54386-Q1www.
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comSLUSAZ9A–MARCH2012–REVISEDMARCH2012POWERDISSIPATIONvsAMBIENTTEMPERATUREFigure33.
Power-DeratingCurvesPowerPADPackageThePowerPADpackageprovideslowthermalimpedanceforheatremovalfromthedevice.
Thethermalpadderivesitsnameandlowthermalimpedancefromthelargebondingpadonthebottomofthedevice.
Thecircuitboardmusthaveanareaofsolder-tinned-copperunderneaththepackage.
ThedimensionsofthisareadependonthesizeofthePowerPADpackage.
Thermalviasconnectthisareatointernalorexternalcopperplanesandshouldhaveadrilldiametersufficientlysmallsothattheviaholeiseffectivelypluggedwhenthebarreloftheviaisplatedwithcopper.
Thisplugisneededtopreventwickingthesolderawayfromtheinterfacebetweenthepackagebodyandthesolder-tinnedareaunderthedeviceduringsolderreflow.
Drilldiametersof0.
33mm(13mils)workwellwhen1-oz.
copperisplatedatthesurfaceoftheboardwhilesimultaneouslyplatingthebarrelofthevia.
Ifthethermalviasarenotpluggedwhenthecopperplatingisperformed,thenasoldermaskmaterialshouldbeusedtocaptheviaswithadiameterequaltotheviadiameterof0.
1mmminimum.
Thiscappingpreventsthesolderfrombeingwickedthroughthethermalviasandpotentiallycreatingasoldervoidunderthepackage.
(SeetheAdditionalReferencessection.
)PCBLayoutGuidelinesThelayoutguidelinespresentedhereareillustratedinthePCBlayoutexamplesgiveninFigure34andFigure35.
Thethermalpadmustbeconnectedtoalow-current(signal)groundplanehavingalargecoppersurfaceareatodissipateheat.
ExtendthecoppersurfacewellbeyondtheICpackageareatomaximizethermaltransferofheatawayfromtheIC.
ConnecttheGNDpintothethermalpadthrougha10-mil(0.
010-in,or0.
254-mm)widetrace.
PlacetheceramicinputcapacitorsclosetoPVDD1andPVDD2;connectusingshort,widetraces.
MaintainatightloopofwidetracesfromSW1orSW2throughtheswitchnode,inductor,outputcapacitor,andrectifierdiode.
Avoidusingviasinthisloop.
Useawidegroundconnectionfromtheinputcapacitortotherectifierdiode,placedasclosetothepowerpathaspossible.
Placementdirectlyunderthediodeandtheswitchnodeisrecommended.
LocatethebootstrapcapacitorclosetotheBOOTpintominimizethegate-driveloop.
Locatevoltage-settingresistorsandanyfeedbackcomponentsoverthegroundplaneandawayfromtheswitchnodeandtherectifierdiodetotheinput-capacitorgroundconnection.
Locatesnubbercomponents(ifused)closetotherectifierdiodewithminimallooparea.
Copyright2012,TexasInstrumentsIncorporatedSubmitDocumentationFeedback29ProductFolderLink(s):TPS54386-Q1TPS54386-Q1SLUSAZ9A–MARCH2012–REVISEDMARCH2012www.
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comLocatetheBPbypasscapacitorveryclosetotheIC;aminimalloopareaisrecommended.
Locatetheoutputceramiccapacitorclosetotheinductoroutputterminalbetweentheinductorandanyelectrolyticcapacitors,ifused.
Figure34.
TopLayerCopperLayoutandComponentPlacement30SubmitDocumentationFeedbackCopyright2012,TexasInstrumentsIncorporatedProductFolderLink(s):TPS54386-Q1TPS54386-Q1www.
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comSLUSAZ9A–MARCH2012–REVISEDMARCH2012Figure35.
BottomLayerCopperLayoutCopyright2012,TexasInstrumentsIncorporatedSubmitDocumentationFeedback31ProductFolderLink(s):TPS54386-Q1TPS54386-Q1SLUSAZ9A–MARCH2012–REVISEDMARCH2012www.
ti.
comDESIGNEXAMPLESExample1:DetailedDesignofa12-Vto5-Vand3.
3-VConverterThefollowingexampleillustratesadesignprocessandcomponentselectionfora12-Vto5-Vand3.
3-Vdualnon-synchronousbuckregulatorusingtheTPS54386-Q1converter.
DesignExampleListofMaterialsandTable5,DefinitionofSymbolsisfoundattheendofthissection.
PARAMETERNOTESANDCONDITIONSMINNOMMAXUNITINPUTCHARACTERISTICSVINInputvoltage6.
91213.
2VIINInputcurrentVIN=nom,IOUT=max1.
62ANoloadinputcurrentVIN=nom,IOUT=0A1220mAOUTPUTCHARACTERISTICSVOUT1Outputvoltage1VIN=nom,IOUT=nom4.
855.
2VVOUT2Outputvoltage2VIN=nom,IOUT=nom3.
23.
33.
4LineregulationVIN=mintomax1%LoadregulationIOUT=mintomax1%VOUT(rippleOutputvoltagerippleVIN=nom,IOUT=max50mVPP)IOUT1Outputcurrent1VIN=mintomax02IOUT2Outputcurrent2VIN=mintomax02OutputovercurrentchannelAIOCP1VIN=nom,VOUT=VOUT1=5%2.
433.
51OutputovercurrentchannelIOCP2VIN=nom,VOUT=VOUT2=5%2.
433.
52TransientresponseΔVOUTΔIOUT=1Aat3A/μs200mVfromloadtransientTransientresponsesettling1mstimeSYSTEMCHARACTERISTICSfSWSwitchingfrequency250310370kHzηFull-loadefficiency85%OperatingtemperatureTJ02560°CrangeFigure36.
DesignExampleSchematic32SubmitDocumentationFeedbackCopyright2012,TexasInstrumentsIncorporatedProductFolderLink(s):TPS54386-Q1TPS54386-Q1www.
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comSLUSAZ9A–MARCH2012–REVISEDMARCH2012DesignProcedureDutyCycleEstimationThefirststepistoestimatethedutycycleofeachswitchingFET.
(21)(22)Usinganassumedforwarddropof0.
5VforaSchottkyrectifierdiode,thechannel1dutycycleisapproximately40.
1%(minimum)to48.
7%(maximum),whilethechannel2dutycycleisapproximately27.
7%(minimum)to32.
2%(maximum).
InductorSelectionThepeak-to-peakrippleislimitedto30%ofthemaximumoutputcurrent.
Thisplacesthepeakcurrentfarenoughfromtheminimumovercurrenttripleveltoensurereliableoperation.
Forbothchannel1andchannel2,themaximuminductorripplecurrentis600mA.
TheinductorsizeisestimatedinEquation23.
(23)TheinductorvaluesareL1=18.
3μHL2=15.
3μHThenext-higherstandardinductorvalueof22μHisusedforbothinductors.
Theresultingripplecurrentsare:(24)Peak-to-peakripplecurrentsof0.
498Aand0.
416Aareestimatedforchannel1andchannel2,respectively.
ThermscurrentthroughaninductorisapproximatedbyEquation25.
(25)andisapproximately2Aforbothchannels.
Thepeakinductorcurrentisfoundusing:(26)Aninductorwithaminimumrmscurrentratingof2Aandminimumsaturationcurrentratingof2.
25Aisrequired.
ACoilcraftMSS1278-223ML22-μH,6.
8-Ainductorisselected.
RectifierDiodeSelectionASchottkydiodeisselectedasarectifierdiodeforitslowforward-voltagedrop.
Allowing20%overVINforringingontheswitchnode,therequiredminimumreverse-breakdownvoltageoftherectifierdiodeis:(27)Copyright2012,TexasInstrumentsIncorporatedSubmitDocumentationFeedback33ProductFolderLink(s):TPS54386-Q1TPS54386-Q1SLUSAZ9A–MARCH2012–REVISEDMARCH2012www.
ti.
comThediodemusthavereversebreakdownvoltagegreaterthan15.
8V,thereforea20-Vdeviceisused.
TheaveragecurrentintherectifierdiodeisestimatedbyEquation28.
(28)Forthisdesign,1.
2-A(average)and2.
25A(peak)isestimatedforchannel1and1.
5-A(average)and2.
21-A(peak)forchannel2.
AnMBRS320,20-V,3-AdiodeinanSMCpackageisselectedforbothchannels.
Thisdiodehasaforwardvoltagedropof0.
4Vat2A.
ThepowerdissipationinthediodeisestimatedbyEquation29.
(29)Forthisdesign,thefull-loadpowerdissipationisestimatedtobe480mWinD1,and580mWinD2.
OutputCapacitorSelectionTheTPS54386-Q1internalcompensationlimitstheselectionoftheoutputcapacitors.
From,theinternalcompensationhasadoublezeroresonanceatabout3kHz.
TheoutputcapacitorisselectedbyEquation30.
(30)SolvingforCOUTusingfRES=3kHzL=22μHTheresultingisCOUT=128μF.
TheoutputripplevoltageoftheconverteriscomposedoftheripplevoltageacrosstheoutputcapacitanceandtheripplevoltageacrosstheESRoftheoutputcapacitor.
TofindthemaximumESRallowabletomeettheoutputripplerequirements,thetotalrippleispartitionedandtheequationsolvedtofindtheESR.
(31)Basedon128μFofcapacitance,300-kHzswitchingfrequency,and50-mVripplevoltage,plusroundinguptheripplecurrentto0.
5Aandthedutycycleto50%,thecapacitiveportionoftheripplevoltageis6.
5mV,leavingamaximumallowableESRof87m.
Tomeettheripple-voltagerequirements,alow-cost100-μFelectrolyticcapacitorwith400mESR(C5,C17)andtwo10-μFceramiccapacitors(C3andC4;andC18andC19)with2.
5-mESRareselected.
Fromthedatasheetsfortheceramiccapacitors,theparallelcombinationprovidesanimpedanceof28mat300kHzfor14mVofripple.
VoltageSettingTheprimaryfeedbackdividerresistors(R2,R9)fromVOUTtoFBshouldbebetween10kand50ktomaintainabalancebetweenpowerdissipationandnoisesensitivity.
Forthisdesign,20kisselected.
Thelowerresistors,R4andR7arefoundusingthefollowingequations.
(32)(33)R2=R9=20kVFB=0.
8V34SubmitDocumentationFeedbackCopyright2012,TexasInstrumentsIncorporatedProductFolderLink(s):TPS54386-Q1TPS54386-Q1www.
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comSLUSAZ9A–MARCH2012–REVISEDMARCH2012R4=3.
8k(3.
83kstandardvalueisused)R7=6.
4k(6.
34kstandardvalueisused)CompensationCapacitorsCheckingtheESRzerooftheoutputcapacitors:C=100μFESR=400mESR(zero)=3980Hz(34)BecausetheESRzeroofthemainoutputcapacitorislessthan20kHz,anR-CfilterisaddedinparallelwithR4andR7tocompensatefortheESRoftheelectrolyticcapacitorandaddazeroofapproximately40kHz.
fESR(zero)=4kHzfESR(desired)=40kHzR4=3.
83kR5=424(422selected)R7=6.
34kR8=702(698selected)(35)R2=R9=20kREQ1=3.
63kREQ2=5.
51k(36)C8=10.
9nF(10nFselected)C15=7.
22nF(6800pFselected)(37)InputCapacitorSelectionTheTPS54386-Q1datasheetrecommendsaminimum10-μFceramicinputcapacitoroneachPVDDpin.
Thesecapacitorsmustbecapableofhandlingthermsripplecurrentoftheconverter.
ThermscurrentintheinputcapacitorsisestimatedbyEquation38.
(38)IRMS(CIN)=0.
43AOne121010-μF,25-V,X5Rceramiccapacitorwith2-mESRanda2-ArmscurrentratingisselectedforeachPVDDinput.
Higher-voltagecapacitorsareselectedtominimizecapacitancelossatthedcbiasvoltagetoensurethecapacitorsmaintainsufficientcapacitanceattheworkingvoltage.
Copyright2012,TexasInstrumentsIncorporatedSubmitDocumentationFeedback35ProductFolderLink(s):TPS54386-Q1TPS54386-Q1SLUSAZ9A–MARCH2012–REVISEDMARCH2012www.
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comBootstrapCapacitorToensureproperchargingofthehigh-sideFETgateandlimittheripplevoltageontheboostcapacitor,a33-nFbootstrapcapacitorisused.
ILIMCurrentlimitmustbesetabovethepeakinductorcurrentIL(peak).
ComparingIL(peak)totheavailableminimumcurrentlimits,ILIMisconnectedtoBPforthehighestcurrent-limitlevel.
SEQTheSEQpinisleftfloating,leavingtheenablepinstofunctionindependently.
Iftheenablepinsaretiedtogether,thetwosuppliesstartupratiometrically.
Alternatively,SEQcouldbeconnectedtoBPorGNDtoprovidesequentialstart-up.
PowerDissipationThepowerdissipationintheTPS54386-Q1iscomposedofFETconductionlosses,switchinglosses,andinternalregulatorlosses.
ThermsFETcurrentisfoundusingEquation39.
(39)Thisresultsin1.
05-Armsforchannel1and0.
87Armsforchannel2.
Conductionlossesareestimatedby:(40)Conductionlossesof198mWand136mWareestimatedforchannel1andchannel2respectively.
TheswitchinglossesareestimatedinEquation41.
(41)FromthedatasheetoftheMBRS320,thejunctioncapacitanceis658pF.
BecausethisislargecomparedtotheoutputcapacitanceoftheTPS54x8x,theFETcapacitanceisneglected,leavingswitchinglossesof17mWforeachchannel.
TheregulatorlossesareestimatedinEquation42.
(42)WithnoexternalloadonBP(IBP=0),thepowerdissipationoftheregulatoris66mW.
Totalpowerdissipationinthedeviceisthesumofconductionandswitchingforbothchannels,plusregulatorlosses.
ThetotalpowerdissipationisPDISS=0.
198+0.
136+0.
017+0.
017+0.
066=434mW.
DesignExampleTestResultsThefollowingresultsarefromtheTPS54386-Q1-001EVM.
36SubmitDocumentationFeedbackCopyright2012,TexasInstrumentsIncorporatedProductFolderLink(s):TPS54386-Q1TPS54386-Q1www.
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comSLUSAZ9A–MARCH2012–REVISEDMARCH2012Figure37.
Switching-NodeWaveformsFigure38.
5-VOutputEfficiencyvsLoadCurrentFigure39.
3.
3-VOutputEfficiencyvsLoadCurrentCopyright2012,TexasInstrumentsIncorporatedSubmitDocumentationFeedback37ProductFolderLink(s):TPS54386-Q1TPS54386-Q1SLUSAZ9A–MARCH2012–REVISEDMARCH2012www.
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comFigure40.
5-VOutputVoltagevsLoadCurrentFigure41.
3.
3-VOutputVoltagevsLoadCurrentFigure42.
Example1LoopResponse38SubmitDocumentationFeedbackCopyright2012,TexasInstrumentsIncorporatedProductFolderLink(s):TPS54386-Q1TPS54386-Q1www.
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comSLUSAZ9A–MARCH2012–REVISEDMARCH2012Table4.
DesignExampleListofMaterialsREFERENCEQTYVALUEDESCRIPTIONSIZEPARTNUMBERMANUFACTURERDESIGNATOR1C1100μFCapacitor,Aluminum,25V,20%E-canEEEFC1E101PPanasonic2C10,C1110μFCapacitor,Ceramic,25V,X5R20%1210C3216X5R1E106MTDK1C124.
7μFCapacitor,Ceramic,10V,X5R20%0805StdStd2C14,C16470pFCapacitor,Ceramic,25V,X7R,20%0603StdStd1C156.
8nFCapacitor,Ceramic,25V,X7R,20%0603StdStdCapacitor,Aluminum,10V,20%,FC1C17,C5100μFF-canEEEFC1A101PPanasonicSeries4C3,C4,C18,C1910μFCapacitor,Ceramic,6.
3V,X5R20%0805C2012X5R0J106MTDK1C810nFCapacitor,Ceramic,25V,X7R,20%0603StdStd2C9,C130.
033μFCapacitor,Ceramic,25V,X7R,20%0603StdStd2D1,D2MBRS320Diode,Schottky,3-A,30-VSMCMBRS330T3OnSemi0.
484x2L1,L222μHInductor,Power,6.
8A,0.
038MSS1278-153MLCoilcraft0.
4842R2,R920kResistor,Chip,1/16W,1%0603StdStd1R5422Resistor,Chip,1/16W,1%0603StdStd2R6,R1010Resistor,Chip,1/16W,5%0603StdStd1R8698Resistor,Chip,1/16W,1%0603StdStd1R43.
83kResistor,Chip,1/16W,1%0603StdStd1R76.
34kResistor,Chip,1/16W,1%0603StdStdTPS54386-Q1DC-DCSwitchingHTSSOP1U1TPS54386-Q1PWPTIConverterw/FET-14Copyright2012,TexasInstrumentsIncorporatedSubmitDocumentationFeedback39ProductFolderLink(s):TPS54386-Q1TPS54386-Q1SLUSAZ9A–MARCH2012–REVISEDMARCH2012www.
ti.
comTable5.
DefinitionofSymbolsCDJAveragejunctioncapacitanceoftherectifierdiodefrom0VtoVIN(max)COSSAverageoutputcapacitanceoftheswitchingMOSFETfrom0VtoVIN(max)COUTOutputcapacitorD(max)Maximumsteady-stateoperatingdutycycleD(min)Minimumsteady-stateoperatingdutycycleESR(max)Maximumallowableoutput-capacitorESRfSWSwitchingfrequencyIBPOutputcurrentofBPregulatorduetoexternalloadsIDDSwitchingquiescentcurrentwithnoloadonBPID(avg)AveragediodeconductioncurrentID(peak)PeakdiodeconductioncurrentIIN(avg)AverageinputcurrentIIN(rms)Rootmeansquared(RMS)inputcurrentIL(avg)AverageinductorcurrentIL(rms)Rootmeansquared(RMS)inductorcurrentIL(peak)PeakcurrentininductorILRIP(max)MaximumallowableinductorripplecurrentL(min)MinimuminductorvaluetomaintaindesiredripplecurrentIOUT(max)MaximumdesignedoutputcurrentIRMS(cin)Rootmeansquared(RMS)currentthroughtheinputcapacitorIRIPPLEInductorpeak-to-peakripplecurrentIQSW(rms)RootmeansquaredcurrentthroughtheswitchingMOSFETPCONPowerlossduetoconductionthroughswitchingMOSFETPD(max)MaximumpowerdissipationindiodeRDS(on)Drain-to-sourceresistanceoftheswitchingMOSFETwhenONPSWPowerlossduetoswitchingPREGPowerlossduetotheinternalregulatorVBPOutputvoltageofBPregulatorV(BR)R(min)Minimumreverse-breakdownvoltageratingforrectifierdiodeVFBRegulatedfeedbackvoltageVFDForwardvoltagedropacrossrectifierdiodeVINPower-stageinputvoltageVOUTRegulatedoutputvoltageVRIPPLE(cap)Peak-to-peakripplevoltageduetoidealcapacitor(ESR=0Ω)VRIPPLE(tot)Maximumallowablepeak-to-peakoutputripplevoltage40SubmitDocumentationFeedbackCopyright2012,TexasInstrumentsIncorporatedProductFolderLink(s):TPS54386-Q1TPS54386-Q1www.
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comSLUSAZ9A–MARCH2012–REVISEDMARCH2012Example2:24Vto12Vand24Vto5VForahigherinputvoltage,bothasnubberandbootstrapresistorsareaddedtoreduceringingontheswitchnodeanda30-VSchottkydiodeisselected.
Ahigher-resistancefeedbacknetworkischosenforthe12-Voutputtoreducethefeedbackcurrent.
Figure43.
24Vto12Vand24Vto5VUsingtheTPS54386-Q1Figure44.
SwitchNodeRingingWithoutSnubberFigure45.
SwitchNodeRingingWithSnubberandandBoostResistorBoostResistorCopyright2012,TexasInstrumentsIncorporatedSubmitDocumentationFeedback41ProductFolderLink(s):TPS54386-Q1TPS54386-Q1SLUSAZ9A–MARCH2012–REVISEDMARCH2012www.
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comFigure46.
EfficiencyvsLoadCurrent42SubmitDocumentationFeedbackCopyright2012,TexasInstrumentsIncorporatedProductFolderLink(s):TPS54386-Q1TPS54386-Q1www.
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comSLUSAZ9A–MARCH2012–REVISEDMARCH2012Example3:5Vto3.
3Vand5Vto1.
2VForalow-input-voltageapplication,theTPS54386-Q1isselectedforreducedsize,andallceramicoutputcapacitorsareused.
22-μFinputcapacitorsareselectedtoreduceinputrippleandleadcapacitorsareplacedinthefeedbacktoboostphasemargin.
Figure47.
5Vto3.
3Vand5Vto1.
2VFigure48.
EfficiencyvsLoadCurrentFigure49.
Example3LoopResponseCopyright2012,TexasInstrumentsIncorporatedSubmitDocumentationFeedback43ProductFolderLink(s):TPS54386-Q1TPS54386-Q1SLUSAZ9A–MARCH2012–REVISEDMARCH2012www.
ti.
comADDITIONALREFERENCESRelatedDevicesThefollowingpartshavecharacteristicssimilartotheTPS54386-Q1andmaybeofinterest.
Table6.
DevicesRelatedtotheTPS54386-Q1TILITERATUREDEVICEDESCRIPTIONNUMBERSLUS642TPS402225-Vinput,1.
6-Anon-synchronousbuckconverterTPS54283/SLUS7492-Adualnon-synchronousconverterwithintegratedhigh-sideMOSFETTPS54286ReferencesThesereferences,designtools,andlinkstoadditionalreferences,includingdesignsoftware,maybefoundathttp:www.
power.
ti.
comTable7.
ReferencesTILITERATUREDESCRIPTIONNUMBERSLMA002PowerPADThermallyEnhancedPackageApplicationReportSLMA004PowerPADMadeEasySLUP206UndertheHoodOfLowVoltageDC/DCConverters.
SEM1500Topic5,2002SeminarSeriesSLVA057UnderstandingBuckPowerStagesinSwitchmodePowerSuppliesSLUP173DesigningStableControlLoops.
SEM1400,2001SeminarSeriesPackageOutlineandRecommendedPCBFootprintThefollowingpagesoutlinethemechanicaldimensionsofthe14-PinPWPpackageandproviderecommendationsforPCBlayout.
44SubmitDocumentationFeedbackCopyright2012,TexasInstrumentsIncorporatedProductFolderLink(s):TPS54386-Q1PACKAGEOPTIONADDENDUMwww.
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com10-Dec-2020Addendum-Page1PACKAGINGINFORMATIONOrderableDeviceStatus(1)PackageTypePackageDrawingPinsPackageQtyEcoPlan(2)Leadfinish/Ballmaterial(6)MSLPeakTemp(3)OpTemp(°C)DeviceMarking(4/5)SamplesTPS54386TPWPRQ1ACTIVEHTSSOPPWP142000RoHS&GreenNIPDAULevel-3-260C-168HR-40to10554386T(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)Leadfinish/Ballmaterial-OrderableDevicesmayhavemultiplematerialfinishoptions.
Finishoptionsareseparatedbyaverticalruledline.
Leadfinish/Ballmaterialvaluesmaywraptotwolinesifthefinishvalueexceedsthemaximumcolumnwidth.
ImportantInformationandDisclaimer:TheinformationprovidedonthispagerepresentsTI'sknowledgeandbeliefasofthedatethatitisprovided.
TIbasesitsknowledgeandbeliefoninformationprovidedbythirdparties,andmakesnorepresentationorwarrantyastotheaccuracyofsuchinformation.
Effortsareunderwaytobetterintegrateinformationfromthirdparties.
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InnoeventshallTI'sliabilityarisingoutofsuchinformationexceedthetotalpurchasepriceoftheTIpart(s)atissueinthisdocumentsoldbyTItoCustomeronanannualbasis.
OTHERQUALIFIEDVERSIONSOFTPS54386-Q1:PACKAGEOPTIONADDENDUMwww.
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com10-Dec-2020Addendum-Page2Catalog:TPS54386NOTE:QualifiedVersionDefinitions:Catalog-TI'sstandardcatalogproductTAPEANDREELINFORMATION*AlldimensionsarenominalDevicePackageTypePackageDrawingPinsSPQReelDiameter(mm)ReelWidthW1(mm)A0(mm)B0(mm)K0(mm)P1(mm)W(mm)Pin1QuadrantTPS54386TPWPRQ1HTSSOPPWP142000330.
012.
46.
95.
61.
68.
012.
0Q1PACKAGEMATERIALSINFORMATIONwww.
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