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EnglishDataSheet:SLVS892TPS61175ZHCSJF8F–DECEMBER2008–REVISEDAPRIL2019具具有有软软启启动动功功能能和和可可编编程程开开关关频频率率的的TPS611753A高高压压升升压压转转换换器器11特特性性12.
9V至18V输入电压范围3A、40V内部开关高效电源转换:效率高达93%可由外部电阻器设置的频率范围:200kHz至2.
2MHz同步外部开关频率用户定义的软启动至满负载负载较轻时用于输出调节的跳跃开关周期14引脚HTSSOP封装-带PowerPad使用TPS61175以及WEBENCH电源设计器创建定制设计2应应用用5V至12V、24V功率转换支持SEPIC和反激式拓扑结构ADSL调制解调器电视调谐器3说说明明TPS61175是一款具有集成式3A、40V电源开关的单片开关稳压器.
此器件可配置成多种标准开关稳压器拓扑,包括升压、SEPIC和反激式.
该器件具有宽输入电压范围,可支持输入电压来自多节电池或者5V、12V稳压电源轨的应用.
TPS61175使用电流模式脉宽调制(PWM)控制来调节输出电压.
PWM的开关频率由一个外部电阻器或一个外部时钟信号设定.
用户可以在200kHz至2.
2MHz之间对开关频率进行设定.
该器件具有可编程软启动功能,用于限制启动时的浪涌电流,并且还具有其他内置保护特性,如逐脉冲过流限制和热关断.
TPS61175采用带PowerPad的14引脚HTSSOP封装.
器器件件信信息息(1)器器件件型型号号封封装装封封装装尺尺寸寸((标标称称值值))TPS61175HTSSOP(14)5.
00mm*4.
40mm(1)如需了解所有可用封装,请参阅产品说明书末尾的可订购产品附录.
简简化化原原理理图图2TPS61175ZHCSJF8F–DECEMBER2008–REVISEDAPRIL2019www.
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cnCopyright2008–2019,TexasInstrumentsIncorporated目目录录1特特性性.
12应应用用.
13说说明明.
14修修订订历历史史记记录录25PinConfigurationandFunctions.
36Specifications.
46.
1AbsoluteMaximumRatings46.
2ESDRatings.
46.
3RecommendedOperatingConditions.
46.
4ThermalInformation.
56.
5ElectricalCharacteristics.
56.
6TypicalCharacteristics.
67DetailedDescription87.
1Overview87.
2FunctionalBlockDiagram87.
3FeatureDescription.
97.
4DeviceFunctionalModes.
118ApplicationandImplementation128.
1ApplicationInformation.
128.
2TypicalApplication129PowerSupplyRecommendations.
2010Layout.
2010.
1LayoutGuidelines2010.
2LayoutExample2010.
3ThermalConsiderations.
2111器器件件和和文文档档支支持持2211.
1器件支持.
2211.
2开发支持.
2211.
3接收文档更新通知2211.
4社区资源.
2211.
5商标.
2211.
6静电放电警告.
2211.
7Glossary.
2212机机械械、、封封装装和和可可订订购购信信息息.
234修修订订历历史史记记录录ChangesfromRevisionE(February2019)toRevisionFPage已更改SoftStartfigurereferencetopointtothecorrectsoftstartwaveform.
9已更改"≤"signin公式7to14ChangesfromRevisionD(April2016)toRevisionEPageChangedHandingRatingstabletoESDRatings;movedStorageTemperaturetoAbsoluteMaximumRatings4UpdatedsymbolsinThermalInformation5已添加theIIN(MAX)fortheIOUT(max)calculationequation.
14ChangesfromRevisionC(August2014)toRevisionDPageRevisedsecondparagraphofMinimumONTimeandPulseSkippingsectionorclarity.
11ChangesfromRevisionB(February2012)toRevisionCPage已添加处理额定值表,特性说明部分、器件功能模式、应用和实施部分、电源建议部分、布局部分、器件和文档支持部分以及机械、封装和可订购信息部分1ChangesfromRevisionA(October2010)toRevisionBPageReplacedtheDissipationRatingsTablewiththeThermalInformationTable.
4ChangesfromOriginal(December2008)toRevisionAPage已更改将订购信息表-器件型号从TPS61175更改为TPS61175PWP;删除了"封装标记"列13TPS61175www.
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cnZHCSJF8F–DECEMBER2008–REVISEDAPRIL2019Copyright2008–2019,TexasInstrumentsIncorporated5PinConfigurationandFunctionsTSSOP14PinsTopViewPinFunctionsPINI/ODESCRIPTIONNAMENO.
AGND7ISignalgroundoftheICCOMP8OOutputoftheinternaltransconductanceerroramplifier.
AnexternalRCnetworkisconnectedtothispintocompensatetheregulator.
EN4IEnablepin.
Whenthevoltageofthispinfallsbelowtheenablethresholdformorethan10ms,theICturnsoff.
FB9IFeedbackpinforpositivevoltageregulation.
Connecttothecentertapofaresistordividertoprogramtheoutputvoltage.
FREQ10OSwitchfrequencyprogrampin.
Anexternalresistorisconnectedtothispintosetswitchfrequency.
SeeapplicationsectionforinformationonhowtosizetheFREQresistor.
NC11IReservedpin.
Mustconnectthispintoground.
PGND12,13,14IPowergroundoftheIC.
ItisconnectedtothesourceofthePWMswitch.
SS5OSoftstartprogrammingpin.
AcapacitorbetweentheSSpinandGNDpinprogramssoftstarttiming.
SeeApplicationandImplementationforinformationonhowtosizetheSScapacitor.
SW1,2IThisistheswitchingnodeoftheIC.
ConnectSWtotheswitchedsideoftheinductor.
SYNC6ISwitchfrequencysynchronouspin.
CustomerscanuseanexternalsignaltosettheICswitchfrequencybetween200-kHzand2.
2-MHz.
Ifnotused,thispinshouldbetiedtoAGNDasshortaspossibletoavoidnoisecoupling.
ThermalPadThethermalpadshouldbesolderedtotheanalogground.
Ifpossible,usethermalviatoconnecttotopandinternalgroundplanelayersforidealpowerdissipation.
VIN3ITheinputsupplypinfortheIC.
ConnectVINtoasupplyvoltagebetween2.
9Vand18V.
ItisacceptableforthevoltageonthepintobedifferentfromtheboostpowerstageinputforapplicationsrequiringvoltagebeyondVINrange.
4TPS61175ZHCSJF8F–DECEMBER2008–REVISEDAPRIL2019www.
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cnCopyright2008–2019,TexasInstrumentsIncorporated(1)Stressesbeyondthoselistedunderabsolutemaximumratingsmaycausepermanentdamagetothedevice.
Thesearestressratingsonlyandfunctionaloperationofthedeviceattheseoranyotherconditionsbeyondthoseindicatedunderrecommendedoperatingconditionsisnotimplied.
Exposuretoabsolute-maximum-ratedconditionsforextendedperiodsmayaffectdevicereliability.
(2)Allvoltagevaluesarewithrespecttonetworkgroundterminal.
6Specifications6.
1AbsoluteMaximumRatingsoveroperatingfree-airtemperaturerange(unlessotherwisenoted)(1)MINMAXUNITSupplyvoltagesonpinVIN(2)–0.
320VVoltagesonpinsEN(2)–0.
320VVoltageonpinFB,FREQandCOMP(2)–0.
33VVoltageonpinSYNC,SS(2)–0.
37VVoltageonpinSW(2)–0.
340VContinuouspowerdissipationSeeThermalInformationOperatingjunctiontemperaturerange–40150°CStoragetemperature,Tstg–65150°C(1)JEDECdocumentJEP155statesthat500-VHBMallowssafemanufacturingwithastandardESDcontrolprocess.
(2)JEDECdocumentJEP157statesthat250-VCDMallowssafemanufacturingwithastandardESDcontrolprocess.
6.
2ESDRatingsVALUEUNITV(ESD)ElectrostaticdischargeHuman-bodymodel(HBM),perANSI/ESDA/JEDECJS-001(1)±2000VCharged-devicemodel(CDM),perJEDECspecificationJESD22-C101(2)±500(1)Theinductancevaluedependsontheswitchingfrequencyandendapplication.
Whilelargervaluesmaybeused,valuesbetween4.
7-μHand47-μHhavebeensuccessfullytestedinvariousapplications.
RefertoSelectingtheInductorfordetail.
6.
3RecommendedOperatingConditionsoveroperatingfree-airtemperaturerange(unlessotherwisenoted)MINNOMMAXUNITVINInputvoltage2.
918VVOOutputvoltageVIN38VLInductor(1)4.
747μHfSWSwitchingfrequency2002200kHzCIInputcapacitor4.
7μFCOOutputcapacitor4.
7μFVSYNExternalswitchingfrequencylogic5VTAOperatingambienttemperature–4085°CTJOperatingjunctiontemperature–40125°C5TPS61175www.
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cnZHCSJF8F–DECEMBER2008–REVISEDAPRIL2019版权2008–2019,TexasInstrumentsIncorporated(1)有关传统和新热指标的更多信息,请参见应用报告《半导体和IC封装热指标》(文献编号:SPRA953).
6.
4ThermalInformationTHERMALMETRIC(1)TPS61175UNITPWP(HTSSOP)14PINSRθJAJunction-to-ambientthermalresistance45.
2°C/WRθJC(top)Junction-to-case(top)thermalresistance34.
9°C/WRθJBJunction-to-boardthermalresistance30.
1°C/WψJTJunction-to-topcharacterizationparameter1.
5°C/WψJBJunction-to-boardcharacterizationparameter29.
9°C/WRθJC(bot)Junction-to-case(bottom)thermalresistance5.
8°C/W6.
5ElectricalCharacteristicsFSW=1.
2MHz(Rfreq=80k),VIN=3.
6V,TA=–40°Cto+85°C,typicalvaluesareatTA=25°C(unlessotherwisenoted)PARAMETERTESTCONDITIONSMINTYPMAXUNITSUPPLYCURRENTVINInputvoltagerange2.
918VIQOperatingquiescentcurrentintoVinDevicePWMswitchingwithoutload3.
5mAISDShutdowncurrentEN=GND1.
5μAVUVLOUnder-voltagelockoutthreshold2.
52.
7VVhysUnder-voltagelockouthysteresis130mVENABLEANDREFERENCECONTROLVenhENlogichighvoltageVIN=2.
9Vto18V1.
2VVenlENlogiclowvoltageVIN=2.
9Vto18V0.
4VVSYNhSYNlogichighvoltage1.
2VSYNlSYNlogiclowvoltage0.
4VRenENpulldownresistor4008001600kToffShutdowndelay,SSdischargeENhightolow10msVOLTAGEANDCURRENTCONTROLVREFVoltagefeedbackregulationvoltage1.
2041.
2291.
254VIFBVoltagefeedbackinputbiascurrent200nAIsinkComppinsinkcurrentVFB=VREF+200mV,VCOMP=1V50μAIsourceComppinsourcecurrentVFB=VREF–200mV,VCOMP=1V130μAVCCLPComppinclampvoltageHighClamp,VFB=1VLowClamp,VFB=1.
5V30.
75VVCTHComppinthresholdDutycycle=0%0.
95VGeaErroramplifiertransconductance240340440μmhoReaErroramplifieroutputresistance10MfeaErroramplifiercrossoverfrequency500KHz6TPS61175ZHCSJF8F–DECEMBER2008–REVISEDAPRIL2019www.
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cn版权2008–2019,TexasInstrumentsIncorporatedElectricalCharacteristics(接接下下页页)FSW=1.
2MHz(Rfreq=80k),VIN=3.
6V,TA=–40°Cto+85°C,typicalvaluesareatTA=25°C(unlessotherwisenoted)PARAMETERTESTCONDITIONSMINTYPMAXUNITFREQUENCYfSOscillatorfrequencyRfreq=480k0.
160.
210.
26MHzRfreq=80k1.
01.
21.
4Rfreq=40k1.
762.
22.
64DmaxMaximumdutycycleVFB=1V,Rfreq=80k89%93%VFREQFREQpinvoltage1.
229VTmin_onMinimumonpulsewidthRfreq=80k60nsPOWERSWITCHRDS(ON)N-channelMOSFETon-resistanceVIN=VGS=3.
6VVIN=VGS=3.
0V0.
130.
130.
250.
3ILN_NFETN-channelleakagecurrentVDS=40V,TA=25°C1μAOC,OVPANDSSILIMN-ChannelMOSFETcurrentlimitD=Dmax33.
85AISSSoftstartbiascurrentVss=0V6μATHERMALSHUTDOWNTshutdownThermalshutdownthreshold160°CThysteresisThermalshutdownthresholdhysteresis15°C6.
6TypicalCharacteristicsCircuitof图1;L1=D104C2-10μH;D1=SS3P6L-E3/86A,R4=80k,R3=10k,C4=22nF,C2=10μF;VIN=5V,VOUT=24V,IOUT=200mA(unlessotherwisenoted)表表1.
TableOfGraphsFIGUREEfficiencyVIN=5V,VOUT=12V,24V,35V图1EfficiencyVIN=5V,12V;VOUT=24V图2ErroramplifiertransconductancevsTemperature图3SwitchcurrentlimitvsTemperature图4SwitchcurrentlimitvsDutycycle图5FBaccuracyvsTemperature图6LinetransientresponseVIN=4.
5Vto5V图12LoadtransientresponseIOUT=100mAto300mA;referto'compensatingthecontrolloop'foroptimization图13PWMOperation图14PulseskippingNoload图15Start-upC3=47nF图167TPS61175www.
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cnZHCSJF8F–DECEMBER2008–REVISEDAPRIL2019版权2008–2019,TexasInstrumentsIncorporated图图1.
EfficiencyvsOutputCurrent图图2.
EfficiencyvsOutputCurrent图图3.
ErrorAmplifierTransconductancevsFree-AirTemperature图图4.
OvercurrentLimitvsDutyCycle图图5.
OvercurrentLimitvsFree-AirTemperature图图6.
FBVoltagevsFree-AirTemperature8TPS61175ZHCSJF8F–DECEMBER2008–REVISEDAPRIL2019www.
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cn版权2008–2019,TexasInstrumentsIncorporated7DetailedDescription7.
1OverviewTheTPS61175integratesa40-Vlow-sideswitchFETforupto38-Voutput.
Thedeviceregulatestheoutputwithcurrentmodepulsewidthmodulation(PWM)control.
ThePWMcontrolcircuitryturnsontheswitchatthebeginningofeachswitchingcycle.
Theinputvoltageisappliedacrosstheinductorandstorestheenergyasinductorcurrentrampsup.
Duringthisportionoftheswitchingcycle,theloadcurrentisprovidedbytheoutputcapacitor.
Whentheinductorcurrentrisestothethresholdsetbytheerroramplifieroutput,thepowerswitchturnsoffandtheexternalSchottkydiodeisforwardbiased.
Theinductortransfersstoredenergytoreplenishtheoutputcapacitorandsupplytheloadcurrent.
Thisoperationrepeatseacheveryswitchingcycle.
AsshowninFunctionalBlockDiagram,thedutycycleoftheconverterisdeterminedbythePWMcontrolcomparatorwhichcomparestheerroramplifieroutputandthecurrentsignal.
Theswitchingfrequencyisprogrammedbytheexternalresistororsynchronizedtoanexternalclocksignal.
Arampsignalfromtheoscillatorisaddedtothecurrentramptoprovideslopecompensation.
Slopecompensationisnecessarytoavoidsubharmonicoscillationthatisintrinsictothecurrentmodecontrolatdutycyclehigherthan50%.
Iftheinductorvalueislowerthan4.
7μH,theslopecompensationmaynotbeadequate.
ThefeedbackloopregulatestheFBpintoareferencevoltagethroughatransconductanceerroramplifier.
TheoutputoftheerroramplifierisconnectedtotheCOMPpin.
AnexternalRCcompensationnetworkisconnectedtotheCOMPpintooptimizethefeedbackloopforstabilityandtransientresponse.
7.
2FunctionalBlockDiagram9TPS61175www.
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cnZHCSJF8F–DECEMBER2008–REVISEDAPRIL2019版权2008–2019,TexasInstrumentsIncorporated7.
3FeatureDescription7.
3.
1SwitchingFrequencyTheswitchfrequencyissetbyaresistor(R4)connectedtotheFREQpinoftheTPS61175.
Donotleavethispinopen.
Aresistormustalwaysbeconnectedforproperoperation.
See表2and图7forresistorvaluesandcorrespondingfrequencies.
表表2.
SwitchingFrequencyvsExternalResistorR4(k)fSW(kHz)443240256400176600801200512000图图7.
SwitchingFrequencyvsExternalResistorAlternatively,theTPS61175switchingfrequencywillsynchronizetoanexternalclocksignalthatisappliedtotheSYNCpin.
Thelogicleveloftheexternalclockisshowninthespecificationtable.
Thedutycycleoftheclockisrecommendedintherangeof10%to90%.
TheresistoralsomustbeconnectedtotheFREQpinwhenICisswitchingbytheexternalclock.
Theexternalclockfrequencymustbewithin±20%ofthecorrespondingfrequencysetbytheresistor.
Forexample,ifthecorrespondingfrequencyassetbyaresistorontheFREQpinis1.
2-MHz,theexternalclocksignalshouldbeintherangeof0.
96MHzto1.
44MHz.
IftheexternalclocksignalishigherthanthefrequencypertheresistorontheFREQpin,themaximumdutycyclespecification(DMAX)shouldbeloweredby2%.
Forinstance,iftheresistorsetvalueis2.
5MHz,andtheexternalclockis3MHz,DMAXis87%insteadof89%.
7.
3.
2SoftStartTheTPS61175hasabuilt-insoftstartcircuitwhichsignificantlyreducesthestart-upcurrentspikeandoutputvoltageovershoot.
WhentheICisenabled,aninternalbiascurrent(6μAtypically)chargesacapacitor(C3)ontheSSpin.
ThevoltageatthecapacitorclampstheoutputoftheinternalerroramplifierthatdeterminesthedutycycleofPWMcontrol,therebytheinputinrushcurrentiseliminated.
Oncethecapacitorreaches1.
8V,thesoftstartcycleiscompletedandthesoft-startvoltagenolongerclampstheerroramplifieroutput.
Referto图16forthesoftstartwaveform.
See表3forC3andcorrespondingsoftstarttime.
A47-nFcapacitoreliminatestheoutputovershootandreducesthepeakinductorcurrentformostapplications.
10TPS61175ZHCSJF8F–DECEMBER2008–REVISEDAPRIL2019www.
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cn版权2008–2019,TexasInstrumentsIncorporated表表3.
Soft-StartTimevsC3VIN(V)VOUT(V)LOAD(A)COUT(μF)fSW(MHz)C3(nF)tSS(ms)OVERSHOT(mV)5240.
4101.
2474none100.
821012350.
61021006.
5none100.
4300WhentheENispulledlowfor10ms,theICentersshutdownandtheSScapacitordischargesthrougha5-kresistorforthenextsoftstart.
7.
3.
3OvercurrentProtectionTheTPS61175hasacycle-by-cycleovercurrentlimitprotectionthatturnsoffthepowerswitchoncetheinductorcurrentreachestheovercurrentlimitthreshold.
ThePWMcircuitryresetsitselfatthebeginningofthenextswitchcycle.
Duringanovercurrentevent,theoutputvoltagebeginstodroopasafunctionoftheloadontheoutput.
WhentheFBvoltagedropslowerthan0.
9V,theswitchingfrequencyisautomaticallyreducedto1/4ofthesetvalue.
Theswitchingfrequencydoesnotresetuntiltheovercurrentconditionisremoved.
Thisfeatureisdisabledduringsoftstart.
7.
3.
4EnableandThermalShutdownTheTPS61175entersshutdownwhentheENvoltageislessthan0.
4Vformorethan10ms.
Inshutdown,theinputsupplycurrentforthedeviceislessthan1.
5μA(maximum).
TheENpinhasaninternal800-kpulldownresistortodisablethedevicewhenitisfloating.
Aninternalthermalshutdownturnsoffthedevicewhenthetypicaljunctiontemperatureof160°Cisexceeded.
TheICrestartswhenthejunctiontemperaturedropsby15°C.
7.
3.
5UndervoltageLockout(UVLO)Anundervoltagelockoutcircuitpreventsmis-operationofthedeviceatinputvoltagesbelow2.
5-V(typical).
Whentheinputvoltageisbelowtheundervoltagethreshold,thedeviceremainsoff,andtheinternalswitchFETisturnedoff.
TheUVLOthresholdissetbelowminimumoperatingvoltageof2.
9VtoavoidanytransientVINdiptriggeringtheUVLOandcausingthedevicetoreset.
FortheinputvoltagesbetweenUVLOthresholdand2.
9V,thedeviceattemptstooperate,butthespecificationsarenotensured.
11TPS61175www.
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cnZHCSJF8F–DECEMBER2008–REVISEDAPRIL2019版权2008–2019,TexasInstrumentsIncorporated7.
4DeviceFunctionalModes7.
4.
1MinimumONTimeandPulseSkippingOncethePWMswitchisturnedon,theTPS61175hasminimumONpulsewidthof60ns.
ThissetsthelimitoftheminimumdutycycleofthePWMswitch,anditisindependentofthesetswitchingfrequency.
WhenoperatingconditionsresultintheTPS61175havingaminimumONpulsewidthlessthan60ns,theICenterspulse-skippingmode.
Inthismode,thedevicekeepsthepowerswitchoffforseveralswitchingcyclestokeeptheoutputvoltagefromrisingabovetheregulatedvoltage.
ThisoperationtypicallyoccursinlightloadconditionwhenthePWMoperatesindiscontinuousmode.
Pulseskippingincreasestheoutputvoltageripple,see图15.
Whensettingswitchingfrequencyhigherthan1.
2MHz,TIrecommendsusinganexternalsynchronousclockasswitchingfrequencytoensurepulse-skippingfunctionworksatlightload.
Whenusingtheinternalswitchingfrequencyabove1.
2MHz,thepulse-skippingoperationmaynotfunction.
Whenthepulse-skippingfunctiondoesnotworkatlightload,theTPS61175alwaysrunsinPWMmodewithminimumONpulsewidth.
Tokeeptheoutputvoltageinregulation,aminimumloadisrequired.
Theminimumloadisrelatedtotheinputvoltage,outputvoltage,switchingfrequency,externalinductorvalueandthemaximumvalueoftheminimumONpulsewidth.
Use公式1and公式2tocalculatetherequiredminimumloadattheworstcase.
Themaximumtmin_ONcouldbeestimatedto80ns.
CSWisthetotalparasitecapacitanceattheswitchingnodeSWpin.
Itcouldbeestimatedto100pF.
(1)(2)12TPS61175ZHCSJF8F–DECEMBER2008–REVISEDAPRIL2019www.
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cn版权2008–2019,TexasInstrumentsIncorporated8ApplicationandImplementation8.
1ApplicationInformationThefollowingsectionprovidesastep-by-stepdesignapproachforconfiguringtheTPS61175asavoltageregulatingboostconverter,asshownin图8.
WhenconfiguredasSEPICorflybackconverter,adifferentdesignapproachisrequired.
8.
2TypicalApplication图图8.
BoostConverterConfiguration8.
2.
1DesignRequirements表表4.
DesignParametersPARAMETERSVALUESInputvoltage5VOutputvoltage24VOperatingfrequency1.
2MHz8.
2.
2DetailedDesignProcedure8.
2.
2.
1CustomDesignwithWEBENCHToolsClickheretocreateacustomdesignusingtheTPS61175devicewiththeWEBENCHPowerDesigner.
1.
StartbyenteringyourVIN,VOUTandIOUTrequirements.
2.
Optimizeyourdesignforkeyparameterslikeefficiency,footprintandcostusingtheoptimizerdialandcomparethisdesignwithotherpossiblesolutionsfromTexasInstruments.
3.
WEBENCHPowerDesignerprovidesyouwithacustomizedschematicalongwithalistofmaterialswithrealtimepricingandcomponentavailability.
4.
Inmostcases,youwillalsobeableto:–Runelectricalsimulationstoseeimportantwaveformsandcircuitperformance,–Runthermalsimulationstounderstandthethermalperformanceofyourboard,–ExportyourcustomizedschematicandlayoutintopopularCADformats,–PrintPDFreportsforthedesign,andshareyourdesignwithcolleagues.
5.
GetmoreinformationaboutWEBENCHtoolsatwww.
ti.
com/webench.
13TPS61175www.
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cnZHCSJF8F–DECEMBER2008–REVISEDAPRIL2019版权2008–2019,TexasInstrumentsIncorporated8.
2.
2.
2DeterminingtheDutyCycleTheTPS61175hasamaximumworstcasedutycycleof89%andaminimumontimeof60ns.
Thesetwoconstraintsplacelimitationsontheoperatingfrequencythatcanbeusedforagiveninputtooutputconversionratio.
Thedutycycleatwhichtheconverteroperatesisdependentonthemodeinwhichtheconverterisrunning.
Iftheconverterisrunningindiscontinuousconductionmode(DCM),wheretheinductorcurrentrampstozeroattheendofeachcycle,thedutycyclevarieswithchangestotheloadmuchmorethanitdoeswhenrunningincontinuousconductionmode(CCM).
Incontinuousconductionmode,wheretheinductormaintainsadccurrent,thedutycycleisrelatedprimarilytotheinputandoutputvoltagesascomputedin公式3:(3)Indiscontinuousmodethedutycycleisafunctionoftheload,inputandoutputvoltages,inductanceandswitchingfrequencyascomputedin公式4:(4)Allconvertersusingadiodeasthefreewheelingorcatchcomponenthavealoadcurrentlevelatwhichtheytransitionfromdiscontinuousconductiontocontinuousconduction.
Thisisthepointwheretheinductorcurrentjustfallstozero.
Athigherloadcurrents,theinductorcurrentdoesnotfalltozerobutremainsflowinginapositivedirectionandassumesatrapezoidalwaveshapeasopposedtoatriangularwaveshape.
Thisloadboundarybetweendiscontinuousconductionandcontinuousconductioncanbefoundforasetofconverterparametersin公式5:(5)Forloadshigherthantheresultof公式5,thedutycycleisgivenby公式3andforloadslessthattheresultsof公式4,thedutycycleisgiven公式5.
For公式3through公式5,thevariabledefinitionsareasfollows:VOUTistheoutputvoltageoftheconverterinVVDistheforwardconductionvoltagedropacrosstherectifierorcatchdiodeinVVINistheinputvoltagetotheconverterinVIOUTistheoutputcurrentoftheconverterinAListheinductorvalueinHfSWistheswitchingfrequencyinHzUnlessotherwisestated,thedesignequationsthatfollowassumethattheconverterisrunningincontinuousmode.
8.
2.
2.
3SelectingtheInductorTheselectionoftheinductoraffectssteadystateoperationaswellastransientbehaviorandloopstability.
Thesefactorsmakeitthemostimportantcomponentinpowerregulatordesign.
Therearethreeimportantinductorspecifications,inductorvalue,DCresistanceandsaturationcurrent.
Consideringinductorvaluealoneisnotenough.
Inductorvaluescanhave±20%tolerancewithnocurrentbias.
Whentheinductorcurrentapproachessaturationlevel,itsinductancecanfalltosomepercentageofits0-Avaluedependingonhowtheinductorvendordefinessaturationcurrent.
ForCCMoperation,theruleofthumbistochoosetheinductorsothatitsinductorripplecurrent(ΔIL)isnomorethanacertainpercentage(RPL%=20–40%)ofitsaverageDCvalue(IIN(AVG)=IL(AVG)).
(6)RearrangingandsolvingforLgives:14TPS61175ZHCSJF8F–DECEMBER2008–REVISEDAPRIL2019www.
ti.
com.
cn版权2008–2019,TexasInstrumentsIncorporated(7)Choosingtheinductorripplecurrenttocloserto20%oftheaverageinductorcurrentresultsinalargerinductancevalue,maximizestheconverter'spotentialoutputcurrentandminimizesEMI.
Choosingtheinductorripplecurrentcloserto40%ofIL(AVG)resultsinasmallerinductancevalue,andaphysicallysmallerinductor,improvestransientresponsebutresultsinpotentiallyhigherEMIandlowerefficiencyiftheDCRofthesmallerpackagedinductorissignificantlyhigher.
UsinganinductorwithasmallerinductancevaluethancomputedabovemayresultintheconverteroperatinginDCM.
Thisreducesthemaximumoutputcurrentoftheboostconverter,causeslargerinputvoltageandoutputripple,andtypicallyreducesefficiency.
表5liststherecommendedinductorfortheTPS61175.
表表5.
RecommendedInductorsforTPS61175PARTNUMBERL(μH)DCRMAX(m)SATURATIONCURRENT(A)SIZE(L*W*Hmm)VENDORD104C210443.
610.
4*10.
4*4.
8TOKOVLF1004015423.
110*9.
7*4TDKCDRH105RNP22612.
910.
5*10.
3*5.
1SumidaMSS103815503.
810*10.
2*3.
8CoilcraftThedevicehasbuilt-inslopecompensationtoavoidsubharmonicoscillationassociatedwithcurrentmodecontrol.
Iftheinductorvalueislowerthan4.
7μH,theslopecompensationmaynotbeadequate,andtheloopcanbeunstable.
Applicationsrequiringinductorsabove47μHhavenotbeenevaluated.
Therefore,theuserisresponsibleforverifyingoperationiftheyselectaninductorthatisoutsidethe4.
7-μHto47-μHrecommendedrange.
8.
2.
2.
4ComputingtheMaximumOutputCurrentTheover-currentlimitfortheintegratedpowerFETlimitsthemaximuminputcurrentandthusthemaximuminputpowerforagiveninputvoltage.
Maximumoutputpowerislessthanmaximuminputpowerduetopowerconversionlosses.
Therefore,thecurrentlimitsetting,inputvoltage,outputvoltageandefficiencycanallchangethemaximumcurrentoutput(IOUT(MAX)).
Thecurrentlimitclampsthepeakinductorcurrent,thereforetheripplehastobesubtractedtoderivemaximumDCcurrent.
whereILIM=overcurrentlimitηest=efficiencyestimatebasedonsimilarapplicationsorcomputedabove(8)Forinstance,whenVIN=12VisboostedtoVOUT=24V,theinductoris10H,theSchottkyforwardvoltageis0.
4V,andtheswitchingfrequencyis1.
2MHz;thenthemaximumoutputcurrentis1.
2Aintypicalcondition,assuming90%efficiencyanda%RPL=20%.
8.
2.
2.
5SettingOutputVoltageTosettheoutputvoltageineitherDCMorCCM,selectthevaluesofR1andR2accordingto公式9:(9)ConsideringtheleakagecurrentthroughtheresistordividerandnoisedecouplingintoFBpin,anoptimumvalueforR2isaround10k.
TheoutputvoltagetolerancedependsontheVFBaccuracyandthetoleranceofR1andR2.
15TPS61175www.
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cnZHCSJF8F–DECEMBER2008–REVISEDAPRIL2019版权2008–2019,TexasInstrumentsIncorporated8.
2.
2.
6SettingtheSwitchingFrequencyChoosetheappropriateresistorfromtheresistanceversusfrequencytable表2orgraph图7.
AresistormustbeplacedfromtheFREQpintoground,evenifanexternaloscillationisappliedforsynchronization.
Increasingswitchingfrequencyreducesthevalueofexternalcapacitorsandinductors,butalsoreducesthepowerconversionefficiency.
Theusershouldsetthefrequencyfortheminimumtolerableefficiency.
8.
2.
2.
7SettingtheSoft-StartTimeChoosetheappropriatecapacitorfromthesoft-starttable,表3.
Increasingthesoft-starttimereducestheovershootduringstart-up.
8.
2.
2.
8SelectingtheSchottkyDiodeThehighswitchingfrequencyoftheTPS61175demandsahigh-speedrectificationforoptimumefficiency.
Ensurethatthediode'saverageandpeakcurrentratingexceedtheaverageoutputcurrentandpeakinductorcurrent.
Inaddition,thediode'sreversebreakdownvoltagemustexceedtheswitchFETratingvoltageof40V.
So,theVISHAYSS3P6L-E3/86AisrecommendedforTPS61175.
Thepowerdissipationofthediode'spackagemustbelargerthanIOUT(max)*VD.
8.
2.
2.
9SelectingtheInputandOutputCapacitorsTheoutputcapacitorismainlyselectedtomeettherequirementsfortheoutputrippleandloadtransient.
Thentheloopiscompensatedfortheoutputcapacitorselected.
Theoutputripplevoltageisrelatedtothecapacitor'scapacitanceanditsequivalentseriesresistance(ESR).
AssumingacapacitorwithzeroESR,theminimumcapacitanceneededforagivenripplecanbecalculatedusing公式10:(10)whereVripple=peaktopeakoutputripple.
TheadditionaloutputripplecomponentcausedbyESRiscalculatedusing:Vripple_ESR=I*RESRDuetoitslowESR,Vripple_ESRcanbeneglectedforceramiccapacitors,butmustbeconsiderediftantalumorelectrolyticcapacitorsareused.
Theminimumceramicoutputcapacitanceneededtomeetaloadtransientrequirementcanbeestimatedusing公式11:whereΔITRANisthetransientloadcurrentstepΔVTRANistheallowedvoltagedipfortheloadcurrentstepfLOOP-BWisthecontrolloopbandwidth(thatis,thefrequencywherethecontrolloopgaincrosseszero).
(11)Caremustbetakenwhenevaluatingaceramiccapacitor'sderatingunderDCbias,agingandACsignal.
Forexample,largerformfactorcapacitors(in1206size)havetheirselfresonantfrequenciesintherangeoftheswitchingfrequency.
Sotheeffectivecapacitanceissignificantlylower.
TheDCbiascanalsosignificantlyreducecapacitance.
Ceramiccapacitorscanlossasmuchas50%ofitscapacitanceatitsratedvoltage.
Therefore,onemustaddmarginonthevoltageratingtoensureadequatecapacitanceattherequiredoutputvoltage.
Foratypicalboostconverterimplementation,atleast4.
7μFofceramicinputandoutputcapacitanceisrecommended.
Additionalinputandoutputcapacitancemayberequiredtomeetrippleand/ortransientrequirements.
Thepopularvendorsforhighvalueceramiccapacitorsare:TDK(http://www.
component.
tdk.
com/components.
php)Murata(http://www.
murata.
com/cap/index.
html)16TPS61175ZHCSJF8F–DECEMBER2008–REVISEDAPRIL2019www.
ti.
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cn版权2008–2019,TexasInstrumentsIncorporated8.
2.
2.
10CompensatingtheSmallSignalControlLoopAllcontinuousmodeboostconvertershavearighthalfplanezero(RHPZ)duetotheinductorbeingremovedfromtheoutputduringcharging.
Inatraditionalvoltagemodecontrolledboostconverter,theinductorandoutputcapacitorformasmallsignaldoublepole.
Foranegativefeedbacksystemtobestable,thefedbacksignalmusthaveagainlessthan1beforehaving180degreesofphaseshift.
WithitsdoublepoleandRHPZallprovidingphaseshift,voltagemodeboostconvertersareachallengetocompensate.
Inaconverterwithcurrentmodecontrol,thereareessentiallytwoloops,aninnercurrentfeedbackloopcreatedbytheinductorcurrentinformationsensedacrossRSENSE(40m)andtheoutputvoltagefeedbackloop.
Theinnercurrentloopallowstheswitch,inductorandmodulatortobelumpedtogetherintoasmallsignalvariablecurrentsourcecontrolledbytheerroramplifier,asshownin图9.
图图9.
SmallSignalModelofaCurrentModeBoostinCCMThenewpowerstage,includingtheslopecompensation,smallsignalmodelbecomes:(12)Where(13)(14)(15)And(16)He(s)modelstheinductorcurrentsamplingeffectaswellastheslopecompensationeffectonthesmallsignalresponse.
NotethatifSn>Se,forexample,whenLissmallerthanrecommended,theconverteroperatesasavoltagemodeconverterandtheabovemodelnolongerholds.
17TPS61175www.
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cnZHCSJF8F–DECEMBER2008–REVISEDAPRIL2019版权2008–2019,TexasInstrumentsIncorporatedTheslopecompensationinTPS61175isshownasfollows:(17)WhereR4isthefrequencysettingresistor(18)图10showsaBodeplotofatypicalCCMboostconverterpowerstage.
图图10.
BodePlotofPowerStageGainandPhaseTheTPS61175COMPpinistheoutputoftheinternaltrans-conductanceamplifier.
公式19showstheequationforfeedbackresistornetworkandtheerroramplifier.
whereGEAandREAaretheamplifier'strans-conductanceandoutputresistancelocatedintheElectricalCharacteristicstable.
(19)(20)C5isoptionalandcanbemodeledas10pFstraycapacitance.
(21)and(22)图11showsatypicalbodeplotfortransferfunctionH(s).
18TPS61175ZHCSJF8F–DECEMBER2008–REVISEDAPRIL2019www.
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cn版权2008–2019,TexasInstrumentsIncorporated图图11.
BodePlotofFeedbackResistorsandCompensatedAmplifierGainandPhaseThenextstepistochoosetheloopcrossoverfrequency,fC.
Thehigherinfrequencythattheloopgainstaysabovezerobeforecrossingover,thefastertheloopresponsewillbeandthereforethelowertheoutputvoltagewilldroopduringastepload.
Itisgenerallyacceptedthattheloopgaincrossovernohigherthanthelowerofeither1/5oftheswitchingfrequency,fSW,or1/3oftheRHPZfrequency,fRHPZ.
Toapproximateasinglepoleroll-offuptofP2,selectR3sothatthecompensationgain,KCOMP,atfCon图11isthereciprocalofthegain,KPW,readatfrequencyfCfromthe图10bodeplot,ormoresimply:KCOMP(fC)=20*log(GEA*R3*R2/(R2+R1))=1/KPW(fC)Thismakesthetotalloopgain,T(s)=GPS(s)*HEA(s),zeroatthefC.
Then,selectC4sothatfZfC/10andoptionalfP2>fC*10.
Followingthismethodshouldleadtoaloopwithaphasemarginnear45degrees.
LoweringR3whilekeepingfZfC/10increasesthephasemarginandthereforeincreasesthetimeittakesfortheoutputvoltagetosettlefollowingastepload.
IntheTPS61175,iftheFBpinvoltagechangessuddenlyduetoaloadstepontheoutputvoltage,theerroramplifierincreasesitstransconductancefor8-msinanefforttospeeduptheIC'stransientresponseandreduceoutputvoltagedroopduetotheloadstep.
Forexample,iftheFBvoltagedecreases10mVduetoloadchange,theerroramplifierincreasesitssourcecurrentthroughCOMPby5times;ifFBvoltageincreases11mV,thesinkcurrentthroughCOMPisincreasedto3.
5timesnormalvalue.
Thisfeatureoftenresultsinsawtoothringingontheoutputvoltage,shownas图13.
Designingtheloopforgreaterthan45degreesofphasemarginandgreaterthan10-dbgainmarginminimizestheamplitudeofthisringing.
Thisfeatureisdisabledduringsoftstart.
19TPS61175www.
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cnZHCSJF8F–DECEMBER2008–REVISEDAPRIL2019版权2008–2019,TexasInstrumentsIncorporated8.
2.
3ApplicationCurves图图12.
LineTransientResponse图图13.
LoadTransientResponse图图14.
PWMOperation图图15.
PulseSkipping图图16.
SoftStart-up20TPS61175ZHCSJF8F–DECEMBER2008–REVISEDAPRIL2019www.
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cn版权2008–2019,TexasInstrumentsIncorporated9PowerSupplyRecommendationsThedeviceisdesignedtooperatefromaninputvoltagesupplyrangebetween2.
9Vand18V.
Theinputpowersupply'soutputcurrentmustberatedaccordingtothesupplyvoltage,outputvoltageandoutputcurrentoftheTPS61175.
10Layout10.
1LayoutGuidelinesAsforallswitchingpowersupplies,especiallythoserunningathighswitchingfrequencyandhighcurrents,layoutisanimportantdesignstep.
Iflayoutisnotcarefullydone,theregulatorcouldsufferfrominstabilityaswellasnoiseproblems.
Tomaximizeefficiency,switchriseandfalltimesareveryfast.
Topreventradiationofhighfrequencynoise(forexample,EMI),properlayoutofthehighfrequencyswitchingpathisessential.
MinimizethelengthandareaofalltracesconnectedtotheSWpinandalwaysuseagroundplaneundertheswitchingregulatortominimizeinterplanecoupling.
Thehighcurrentpathincludingtheswitch,Schottkydiode,andoutputcapacitor,containsnanosecondriseandfalltimesandmustbekeptasshortaspossible.
TheinputcapacitormustnotonlytobeclosetotheVINpin,butalsototheGNDpininordertoreducetheIinputsupplyripple.
10.
2LayoutExample图图17.
TPS61175Layout21TPS61175www.
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cnZHCSJF8F–DECEMBER2008–REVISEDAPRIL2019版权2008–2019,TexasInstrumentsIncorporated10.
3ThermalConsiderationsRestrictthemaximumICjunctiontemperatureto125°Cundernormaloperatingconditions.
ThisrestrictionlimitsthepowerdissipationoftheTPS61175.
Calculatethemaximumallowabledissipation,PD(maximum),andkeeptheactualdissipationlessthanorequaltoPD(maximum).
Themaximum-power-dissipationlimitisdeterminedusing公式23:whereTAisthemaximumambienttemperaturefortheapplicationRθJAisthethermalresistancejunction-to-ambientgiveninThermalInformation.
(23)TheTPS61175comesinathermallyenhancedTSSOPpackage.
Thispackageincludesathermalpadthatimprovesthethermalcapabilitiesofthepackage.
TheRθJAoftheTSSOPpackagegreatlydependsonthePCBlayoutandthermalpadconnection.
ThethermalpadmustbesolderedtotheanaloggroundonthePCB.
Usingthermalviasunderneaththethermalpad.
22TPS61175ZHCSJF8F–DECEMBER2008–REVISEDAPRIL2019www.
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cn版权2008–2019,TexasInstrumentsIncorporated11器器件件和和文文档档支支持持11.
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1.
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11.
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1使使用用WEBENCH工工具具创创建建定定制制设设计计请单击此处,使用TPS61175器件以及WEBENCH电源设计器创建定制设计.
1.
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2.
使用优化器拨盘优化效率、封装和成本等关键设计参数并将您的设计与德州仪器(TI)的其它可行解决方案进行比较.
3.
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4.
在大多数情况下,您还可以:–运行电气仿真,观察重要波形以及电路性能;–运行热性能仿真,了解电路板热性能;–将定制原理图和布局方案导出至常用CAD格式,–打印设计方案的PDF报告并与同事共享.
5.
请访问www.
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cn/webench,获取有关WEBENCH工具的详细信息.
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11.
4社社区区资资源源ThefollowinglinksconnecttoTIcommunityresources.
Linkedcontentsareprovided"ASIS"bytherespectivecontributors.
TheydonotconstituteTIspecificationsanddonotnecessarilyreflectTI'sviews;seeTI'sTermsofUse.
TIE2EOnlineCommunityTI'sEngineer-to-Engineer(E2E)Community.
Createdtofostercollaborationamongengineers.
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DesignSupportTI'sDesignSupportQuicklyfindhelpfulE2Eforumsalongwithdesignsupporttoolsandcontactinformationfortechnicalsupport.
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Allothertrademarksarethepropertyoftheirrespectiveowners.
11.
6静静电电放放电电警警告告这些装置包含有限的内置ESD保护.
存储或装卸时,应将导线一起截短或将装置放置于导电泡棉中,以防止MOS门极遭受静电损伤.
11.
7GlossarySLYZ022—TIGlossary.
Thisglossarylistsandexplainsterms,acronyms,anddefinitions.
23TPS61175www.
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