LM5008 High-Voltage, 100-V Step-Down Switching …

1 FBVINVCCSWRTNON TIMERDRIVERVINBSTLEVELSHIFTSD ns MIN OFFTIMER865341277V SERIESREGULATORCURRENT LIMITOFF TIMERSHUTDOWND1 QCLRQSETSR+-+-+-C1 RONRCLR2R3 VOUT2 VOUT1R1C5C2 Copyright 2016, Texas Instruments IncorporatedProductFolderSample &BuyTechnicalDocumentsTools &SoftwareSupport &CommunityAn IMPORTANTNOTICEat the end of this datasheetaddressesavailability,warranty, changes,use in safety-criticalapplications,intellectual propertymattersand APRIL2004 REVISEDDECEMBER2016LM5008 High-Voltage, 100-V step -DownSwitchingRegulator11 Features1 Integrated100-V,N-ChannelBuckSwitch InternalVCCR egulator No LoopCompensationRequired Ultra-FastTransientResponse On-TimeVariesInverselyWithLine Voltage OperatingFrequencyRemainsConstantWithVar yingLine Voltageand LoadCurrent AdjustableOutputVoltage HighlyEfficientOperation PrecisionInternalReference Low BiasCurrent IntelligentCurrentLimitProtection ThermalShutdown 8-PinVSSOPand 8-PinWSON-8(4 mm 4 mm)Packages2 Applications Non-IsolatedTelecommunicationBuckRegulat ors SecondaryHighVoltagePostRegulators 42-VAutomotiveSystems3 DescriptionThe LM5008step-downswitchingregulatorfeature sall of the functionsneededto implementa low-cost,efficient, deviceis easyto implementand is providedinthe 8-pinVSSOPand the basedon ahystereticcontrolschemeusingan on-timeinverselyproportionalto VIN.

2 Thisfeatureallowsthe operatingfrequencyto is implementedwith forcedoff-time,whichis inverselyproportionalto VOUT. :thermalshutdown,VCCundervoltagelockout, gatedriveundervoltagelockout,andmaximumd uty (1)PARTNUMBERPACKAGEBODYSIZE(NOM) LM5008 VSSOP(8) (8) (1) For all availablepackages,see the orderableaddendumatthe end of the BlockDiagram2LM5008 SNVS280H APRIL2004 : LM5008 SubmitDocumentationFeedbackCopyright 2004 2016,TexasInstrumentsIncorporatedTableof Contents1 Pin Configurationand Applicationand Deviceand Mechanical,Packaging,and RevisionHistoryNOTE:Pagenumbersfor previousrevisionsmay differfrompagenumbersin the (March2013)to RevisionHPage AddedESDR atingstable,FeatureDescriptionsection,De viceFunctionalModes,Applicationand Implementationsection,PowerSupplyRecomme ndationssection,Layoutsection,Deviceand DocumentationSupportsection,andMechanica l,Packaging,and DeletedLeadtemperature,soldering(260 C maximum).

3 4 ChangedR JAvaluesFrom:200 C/WTo: C/W(VSSOP)and From:40 C/WTo: 42 C/W(WSON)..4 ChangesfromRevisionF (March2013)to RevisionGPage Changedlayoutof NationalDataSheetto TI VIN2 BST7 VCC3 RCL6 RT/SD4 RTN5 FBNot to scaleEP1SW8 VIN2 BST7 VCC3 RCL6 RT/SD4 RTN5 FBNot to APRIL2004 REVISEDDECEMBER2016 ProductFolderLinks: LM5008 SubmitDocumentationFeedbackCopyright 2004 2016,TexasInstrumentsIncorporated5 Pin Configurationand FunctionsDGKP ackage8-PinVSSOPTop ViewNGUP ackage8-PinWSONTop ViewPin the outputinductor,re-circulatingdiode,and (bootstrapcapacitorinput):an externalcapacitoris requiredbetweenthe BSTand the SW F ceramiccapacitoris internaldiodechargesthe OFFtime set pin: a resistorbetweenthis pin and RTNsets the off-timewhencurrentlimit off-timeis presetto 35 s if FB = 0 = 10 5/ ( + (FB / 10 6 RCL))4 RTNGG roundpin: groundfor the.

4 This pin is connectedto the invertinginputof the regulationthresholdis pin: a resistorbetweenthis pin and VINsets the switchon-timeas a functionof VIN. Theminimumrecommendedon-timeis 400 ns at the pin can be usedfor = 10 10 RON/ VIN7 VCCPO utputfromthe internalhigh 7 V. If an auxiliaryvoltageisavailableto raisethe voltageon this pin, abovethe regulationset point(7 V), the internalseriespassregulatorwill shutdown,reducingthe IC not exceed14 V. This voltageprovidesgatedrivepowerfor the internaldiodeis providedbetweenthis pin and the BSTpin. F decouplingcapacitoris currentlimitedto 10 :recommendedoperatingrangeis V to 95 V. EPGE xposedpad:the exposedpad has no systemgroundplanefor reducedthermalresistance(WSON packageonly).4LM5008 SNVS280H APRIL2004 : LM5008 SubmitDocumentationFeedbackCopyright 2004 2016,TexasInstrumentsIncorporated(1)Stre ssesbeyondthoselistedunderAbsoluteMaximu mRatingsmay causepermanentdamageto the stressratingsonly,whichdo not implyfunctionaloperationof the deviceat theseor any otherconditionsbeyondthoseindicatedunder RecommendedOperatingConditions.

5 Exposureto absolute-maximum-ratedconditionsfor extendedperiodsmay (unlessotherwisenoted)(1)MINMAXUNITVINto GND GND to GND(steady-state) 1 VBSTto VCC100 VBSTto SW14 VVCCto GND14 VAll otherinputsto GND ,Tstg 55150 C(1)JEDEC documentJEP155statesthat 500-VHBM allowssafe manufacturingwith a standardESDcontrolprocess.(2)The humanbodymodelis a 100-pFcapacitordischargedthrougha resistorinto eachpin.(3)JEDEC documentJEP157statesthat 250-VCDM allowssafe manufacturingwith a (ESD)ElectrostaticdischargeHuman-bodymod el(HBM),per ANSI/ESDA/JEDECJS-001(1)(2) 2000 VCharged-devicemodel(CDM),per JEDEC specificationJESD22-C101(3) (unlessotherwisenoted) ,TJ 40125 C(1)For moreinformationabouttraditionaland new thermalmetrics,see theSemiconductorand IC (1) LM5008 UNITDGK(VSSOP)NGU(WSON)8 PINS8 PINSR C/WR JC(top)Junction-to-case(top) C/WR C/W C/W C/WR JC(bot)Junction-to-case(bottom)thermalre sistance APRIL2004 REVISEDDECEMBER2016 ProductFolderLinks: LM5008 SubmitDocumentationFeedbackCopyright 2004 2016,TexasInstrumentsIncorporated(1)All electricalcharacteristicshavingroomtempe raturelimitsare testedduringproductionwith TA= TJ= 25 C.

6 All hot and cold limitsarespecifiedby correlatingthe electricalcharacteristicsto processand temperaturevariationsand applyingstatisticalprocesscontrol.(2)The VCCoutputis intendedas a self bias for the internalgatedrivepowerand for TJ= 25 C and VIN= 48 V (unlessotherwisestated)(1).PARAMETERTEST CONDITIONSMINTYPMAXUNITVCCSUPPLYVCCRegVC CregulatoroutputTJ= 25 C7 VTJ= 40 C to 125 (2) (filter)100-mVoverdrive10 sIINoperatingcurrentNon- Switching ,FB = 3 VTJ= 25 C485 ATJ= 40 C to 125 C675 IINshutdowncurrentRON/SD = 0 VTJ= 25 C76 ATJ= 40 C to 125 C150 CURRENTLIMITC urrentlimit thresholdTJ= 25 40 C to 125 responsetimeIswitchoverdrive= A, time to switchoff400nsOFFtime generator(test1)FB = 0 V, RCL= 100 K35 sOFFtime generator(test2)FB = V, RCL= 100 sON-TIMEGENERATORTON 1 VIN= 10 V, RON= 200 KTJ= 25 sTJ= 40 C to 125 2 VIN= 95 V, RON= 200 KTJ= 25 C300nsTJ= 40 C to 125 C200420 RemoteshutdownthresholdRisingTJ= 25 40 C to 125 = 0 V300nsREGULATIONANDOV COMPARATORSFB referencethresholdInternalreference,trip pointforswitchONTJ= 25 40 C to 125 overvoltagethresholdTrip pointfor bias current100nATHERMALSHUTDOWNTsdThermalshu tdowntemperature165 CThermalshutdownhysteresis25 C(1)For devicesprocuredin the 8-pinWSON packagethe RDS(on)limitsare specifiedby (unlessotherwisenoted)PARAMETERTESTCONDI TIONSMINTYPMAXUNITB uckswitchRDS(on)ITEST= 200 mA(1)TJ= 25 TJ= 40 C to 125 VSWrisingTJ= 25 40 C to 125 CURRENT (mA) (V)VIN = 48 VVOUT1 VOUT2 LOAD CURRENT (mA)EFFICIENCY (%)

7 405060708090100100200300 VIN = 48V VIN = 15 VVIN = (V)MAXIMUNM FREQUENCY (kHz)60V80V95 VMax VIN = LIMIT OFF TIME (Ps)VFB (V)300kRCL = 500k100k50k300k020406080100012345678 TON (Ps)VIN (V)RON = 500k100k891011121314 EXTERNALLY APPLIED VCC (V) INPUT CURRENT (mA)6LM5008 SNVS280H APRIL2004 : LM5008 SubmitDocumentationFeedbackCopyright 2004 2016, ICCC urrentvs AppliedVCCV oltageFigure2. On-Timevs InputVoltageand RONF igure3. MaximumFrequencyvs VOUTand VINF igure4. CurrentLimitOff-Timevs VFBand RCLF igure5. Efficiencyvs LoadCurrentvs VIN(Circuitof Figure10)Figure6. OutputVoltagevs LoadCurrent(Circuitof Figure10)FBVINVCCSWRTNON TIMERDRIVERVINBSTLEVELSHIFTSD ns MIN OFFTIMER865341277V SERIESREGULATORCURRENT LIMITOFF TIMERSHUTDOWND1 QCLRQSETSR+-+-+-C1 RONRCLR2R3 VOUT2 VOUT1R1C5C2 Copyright 2016, Texas Instruments APRIL2004 REVISEDDECEMBER2016 ProductFolderLinks.

8 LM5008 SubmitDocumentationFeedbackCopyright 2004 2016,TexasInstrumentsIncorporated7 LM5008regulatoris an easy-to-usebuckDC-DCconverterthat deviceis intendedfor step -downconversionsfrom12-V,24-V,and 48-Vunregulated, ,the LM5008deliversup to 350-mADC loadcurrentwith exceptionalefficiencyand low inputquiescentcurrentin a very simpleimplementation,a nearlyfixed-frequency,constanton-time(CO T)operationwithdiscontinuousconductionmo de(DCM)at lightloadsis idealfor low-noise,highcurrent,fast compensationis not requiredreducingdesigntime and LM5008incorporatesotherfeaturesfor comprehensivesystemrequirements,includin gVCCundervoltagelockout(UVLO),gatedriveu ndervoltagelockout,maximumdutycyclelimit er,intelligentcurrentlimit off timer,aprechargeswitch,and thermalshutdownwith flexibleand easy-to-use platformfor a widerangeof pin arrangementis designedfor simpleand optimizedPCBlayout,requiringonly a few 2016, Texas Instruments IncorporatedF =VOUT x 10-10 x RONF =VOUT2 x L x x 1020 RL x (RON)28LM5008 SNVS280H APRIL2004 : LM5008 SubmitDocumentationFeedbackCopyright 2004 2016, LM5008is a buckDC-DCregulatorthat usesa controlschemein whichthe on-timevariesinverselywithline voltage(VIN).

9 Controlis basedon a comparatorand the on-timeone-shot,with the outputvoltagefeedback(FB)comparedto an internalreference( V). If the FB levelis belowthe referencethe buckswitchis turnedonfor a fixedtimedeterminedby the line voltageand a programmingresistor(RON). Followingthe ON period,theswitchremainsoff for at leastthe minimumoff-timerperiodof 300 ns. If FB is still belowthe referenceat thattime,the switchturnson againfor will continueuntil regulationis LM5008operatesin discontinuousconductionmodeat light load currents,and continuousconductionmodeat discontinuousconductionmode,currentthrou ghthe outputinductorstartsat zeroandrampsup to a peakduringthe on-time,thenrampsbackto zerobeforethe end of the next on-timeperiodstartswhenthe voltageat FB falls belowthe internalreference;untilthen,the this modethe operatingfrequencyis lowerthanin continuousconductionmode,and varieswith lightloadsthe conversionefficiencyis maintained,becausethe switchinglossesreducewiththe reductionin RL= the load resistance(1)In continuousconductionmode,currentflowscon tinuouslythroughthe inductorand neverrampsdownto this modethe operatingfrequencyis greaterthanthe discontinuousmodefrequencyand remainsrelativelyconstantwith loadand line approximatecontinuousmodeoperatingfreque ncycan be calculatedwith Equation2.

10 (2)The outputvoltage(VOUT) can be programmedby two externalresistorsas regulationpointcan be calculatedwith (R1 + R2) / R2(3)All hystereticregulatorsregulatethe outputvoltagebasedon ripplevoltageat the feedbackinput,requiringaminimumamountof ESRfor the outputcapacitorC2. A minimumof 25 mV to 50 mV of ripplevoltageat thefeedbackpin (FB)is requiredfor the caseswherethe capacitorESRis too small,additionalseriesresistancemay be required(R3 inFunctionalBlockDiagram).For applicationswhereloweroutputvoltagerippl eis requiredthe outputcan be takendirectlyfroma low-ESRoutputcapacitor,as shownin Figure7. However,R3 slightlydegradesthe load Low-RippleOutputConfigurationCopyright 2016, Texas Instruments APRIL2004 REVISEDDECEMBER2016 ProductFolderLinks: LM5008 SubmitDocumentationFeedbackCopyright 2004 2016,TexasInstrumentsIncorporatedFeature Description(continued) LM5008containsan internalhigh inputpin (VIN) can be connecteddirectlytothe line voltagesup to 95 Volts,with transientcapabilityto 100 V.