LM5000

LM5000 High Voltage Switch Mode Regulator datasheet (Rev. D)

Document overview

• Manufacturer or author: Texas Instruments, Incorporated [SNVS176,D]
• PDF pages: 27

Technical content

www.ti.com SNVS176D –MAY 2004–REVISED MARCH 2007 LM5000HighVoltageSwitchModeRegulator Check forSamples: LM5000 1FEATURES DESCRIPTION The LM5000 is a monolithicintegratedcircuit 2• 80V InternalSwitch specificallydesignedand optimizedforflyback,boost• OperatingInputVoltageRange of3.1Vto40V or forwardpower converterapplications.The internal

• Pin SelectableOperatingFrequency power switchisratedfora maximum of 80V, witha currentlimitset to 2A. Protectingthe power switch– 300kHz/700kHz (-3) are currentlimitand thermalshutdown circuits.The– 600kHz/1.3MHz (-6) currentmode controlscheme provides excellent
• AdjustableOutput Voltage rejectionoflinetransientsand cycle-by-cyclecurrent limiting.An externalcompensationpinand thebuilt-in• ExternalCompensation slope compensationallowthe user to optimizethe• InputUndervoltageLockout frequencycompensation.Other distinctivefeatures• Softstart includesoftstartto reduce stressesduringstart-up and an externalshutdown pin forremote ON/OFF• CurrentLimit control.There are two operatingfrequencyranges• Over Temperature Protection available.The LM5000-3 ispinselectableforeither• ExternalShutdown 300kHz (FS Grounded) or 700kHz (FS Open). The
• Small 16-Lead TSSOP or 16-Lead WSON LM5000-6 is pin selectableforeither600kHz (FS Grounded) or 1.3MHz (FS Open). The device isPackage availableina low profile16-leadTSSOP package or a thermallyenhanced 16-leadWSON package.APPLICATIONS
• FlybackRegulator
• Forward Regulator
• Boost Regulator
• DSL Modems
• DistributedPower Converters TypicalApplicationCircuit Figure1. LM5000 FlybackConverter Pleasebe aware thatan importantnoticeconcerningavailability,standardwarranty,and use incriticalapplicationsof Texas Instrumentssemiconductorproductsand disclaimerstheretoappearsattheend ofthisdatasheet. 2Alltrademarksarethepropertyoftheirrespectiveowners. PRODUCTION DATA informationiscurrentas ofpublicationdate. Copyright© 2004–2007,Texas InstrumentsIncorporatedProductsconform to specificationsper the terms of the Texas Instrumentsstandardwarranty.Productionprocessingdoes not necessarilyincludetestingofallparameters.

SNVS176D –MAY 2004–REVISED MARCH 2007 www.ti.com Connection Diagram Figure2. Top View PIN DESCRIPTIONS Pin Name Function 1 COMP Compensationnetworkconnection.Connectedtotheoutputofthevoltageerroramplifier.The RC compenstionnetworkshouldbe connectedfromthispintoAGND. An additional100pF highfrequency capacitortoAGND isrecommended. 2 FB Outputvoltagefeedbackinput. 3 SHDN Shutdown controlinput,Open = enable,Ground = disable. 4 AGND Analogground,connectdirectlytoPGND. 5 PGND Power ground. 6 PGND Power ground. 7 PGND Power ground. 8 PGND Power ground. 9 SW Power switchinput.Switchconnectedbetween SW pinsand PGND pins 10 SW Power switchinput.Switchconnectedbetween SW pinsand PGND pins 11 SW Power switchinput.Switchconnectedbetween SW pinsand PGND pins 12 BYP Bypass-DecoupleCapacitorConnection,0.1µF ceramiccapacitorrecommended. 13 VIN Analogpower input.A smallRC filterisrecommended, tosuppresslineglitches.Typicalvaluesof10Ω and ≥ 0.1µF arerecommended. 14 SS SoftstartInput.Externalcapacitorand internalcurrentsourcesetsthesoftstarttime. 15 FS Switchingfrequencyselectinput.Open = Fhigh.Ground = Flow 16 TEST Factorytestpin,connecttoground. - Exposed Pad Connecttosystemgroundplaneforreducedthermalresistance. undersideofWSON package

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www.ti.com SNVS176D –MAY 2004–REVISED MARCH 2007 These deviceshave limitedbuilt-inESD protection.The leadsshouldbe shortedtogetherorthedeviceplacedinconductivefoam duringstorageorhandlingtopreventelectrostaticdamage totheMOS gates. AbsoluteMaximum Ratings(1)(2) VIN -0.3Vto40V SW Voltage -0.3Vto80V FB Voltage -0.3Vto5V COMP Voltage -0.3Vto3V AllOtherPins -0.3Vto7V Maximum JunctionTemperature 150°C Power Dissipation(3) InternallyLimited Lead Temperature 216°C Infrared(15sec.) 235°C ESD Susceptibility(4) Human Body Model 2kV Machine Model 200V StorageTemperature −65°C to+150°C (1) Absolutemaximum ratingsarelimitsbeyond whichdamage tothedevicemay occur.OperatingRatingsareconditionsforwhichthe deviceisintendedtobe functional,butdeviceparameterspecificationsmay notbe ensured.Forensuredspecificationsand test conditions,see theElectricalCharacteristics. (2) IfMilitary/Aerospacespecifieddevicesarerequired,pleasecontacttheTexas InstrumentsSalesOffice/Distributorsforavailabilityand specifications. (3) The maximum allowablepower dissipationisa functionofthemaximum junctiontemperature,TJ(MAX),thejunction-to-ambientthermal resistance,θJA,and theambienttemperature,TA.See theElectricalCharacteristicstableforthethermalresistanceofvariouslayouts. The maximum allowablepower dissipationatany ambienttemperatureiscalculatedusing:PD (MAX) = (TJ(MAX) − TA)/θJA.Exceeding themaximum allowablepower dissipationwillcause excessivedietemperature,and theregulatorwillgo intothermalshutdown. (4) The human body model isa 100 pF capacitordischargedthrougha 1.5kΩ resistorintoeach pin.The machine model isa 200pF capacitordischargeddirectlyintoeach pin. OperatingConditions OperatingJunctionTemperatureRange (1) −40°C to+125°C SupplyVoltage(1) 3.1Vto40V (1) Supplyvoltage,biascurrentproductwillresultinaditionaldevicepower dissipation.Thispower may be significant.The thermal dissipationdesignshouldtakethisintoaccount. ElectricalCharacteristics SpecificationsinstandardtypefaceareforTJ = 25°C and thosewithboldfacetypeapplyoverthefullOperating Temperature Range (TJ = −40°C to+125°C) Unlessotherwisespecified.VIN = 12V and IL = 0A,unlessotherwisespecified. Symbol Parameter Conditions Min (1) Typ (2) Max (1) Units IQ QuiescentCurrent FB = 2V (NotSwitching) 2.0 2.5 mAFS = 0V FB = 2V (NotSwitching) 2.1 2.5 mAFS = Open VSHDN = 0V 18 30 µA VFB Feedback Voltage 1.2330 1.259 1.2840 V ICL SwitchCurrentLimit 1.35 2.0 2.7 A %V FB /ΔVIN Feedback VoltageLine 3.1V≤ VIN ≤ 40V 0.001 0.04 %/V Regulation IB FB PinBiasCurrent(3) 55 200 nA (1) Alllimitsspecifiedatroom temperature(standardtypeface)and attemperatureextremes(boldtypeface).Allroom temperaturelimitsare 100% productiontested.AlllimitsattemperatureextremesarespecifiedviacorrelationusingstandardStatisticalQualityControl(SQC) methods.Alllimitsareused tocalculateAverageOutgoingQualityLevel(AOQL). (2) Typicalnumbers areat25°C and representthemost likelynorm. (3) BiascurrentflowsintoFB pin. Copyright© 2004–2007,Texas InstrumentsIncorporated SubmitDocumentationFeedback 3 ProductFolderLinks:LM5000

SNVS176D –MAY 2004–REVISED MARCH 2007 www.ti.com ElectricalCharacteristics(continued) SpecificationsinstandardtypefaceareforTJ = 25°C and thosewithboldfacetypeapplyoverthefullOperating Temperature Range (TJ = −40°C to+125°C) Unlessotherwisespecified.VIN = 12V and IL = 0A,unlessotherwisespecified. Symbol Parameter Conditions Min (1) Typ (2) Max (1) Units BV OutputSwitchBreakdown TJ = 25°C, ISW = 0.1µA 80 V Voltage TJ = -40°C to+ 125°C, ISW = 76 0.5µA VIN InputVoltageRange 3.1 40 V gm ErrorAmp Transconductance ΔI= 5µA 150 410 750 µmho AV ErrorAmp VoltageGain 280 V/V D MAX Maximum DutyCycle FS = 0V 85 90 % LM5000-3 Maximum DutyCycle FS = 0V 85 90 % LM5000-6 TMIN Minimum On Time 165 ns fS SwitchingFrequencyLM5000- FS = 0V 240 300 360

3 FS = Open 550 700 840 kHz

SwitchingFrequencyLM5000- FS = 0V 485 600 715 6 FS = Open 1.055 1.3 1.545 MHz ISHDN Shutdown PinCurrent VSHDN = 0V −1 -2 µA IL SwitchLeakage Current VSW = 80V 0.008 5 µA R DSON SwitchR DSON ISW = 1A 160 445 m Ω ThSHDN SHDN Threshold OutputHigh 0.9 0.6 V OutputLow 0.6 0.3 V UVLO On Threshold 2.74 2.92 3.10 V OffThreshold 2.60 2.77 2.96 V OVP VCOMP Trip 0.67 V ISS SoftstartCurrent 8 11 14 µA θJA ThermalResistance TSSOP, Package only 150 °C/W

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VIN (V) 100 150 200 250 300 350 400 R DS (ON) (m:) 25oC 125oC -40oC TEMPERATURE ( oC) FEEDBACK VOLTAGE (V) 1.2300 1.2400 1.2500 1.2600 1.2700 1.2800 -40 -20 0 20 40 60 80 100 120 0 5 10 15 20 25 30 35 40 VIN (V) Iq (mA) -40oC 125oC 25oC 0 5 10 15 20 25 30 35 40 VIN (V) Iq (mA) -40oC 125oC 25oC -40oC 25oC 125oC Iq (mA) 1.000 1.200 1.400 1.600 1.800 2.000 2.200 2.400 2.600 2.800 3.000 VIN (V) 0 5 10 15 20 25 30 35 40 VIN (V) Iq (mA) 1.000 1.200 1.400 1.600 1.800 2.000 2.200 2.400 2.600 2.800 3.000 0 5 10 15 20 25 30 35 40 -40oC 25oC 125oC LM5000 www.ti.com SNVS176D –MAY 2004–REVISED MARCH 2007 TypicalPerformance Characteristics Iq(non-switching)vs VIN @ fSW = 300kHz Iq(non-switching)vs VIN @ fSW = 700kHz Figure3. Figure4. Iq(switching)vs VIN @ fSW = 300kHz Iq(switching)vs VIN @ fSW = 700kHz Figure5. Figure6. Vfb vs Temperature R DS(ON) vs VIN @ ISW =1A Figure7. Figure8. Copyright© 2004–2007,Texas InstrumentsIncorporated SubmitDocumentationFeedback 5 ProductFolderLinks:LM5000

-40 -20 0 20 40 60 80 100 120 TEMPERATURE ( oC) 270 280 290 300 310 320 330 fSW (kHz) fsw (kHz) TEMPERATURE ( oC) -40 -20 0 20 40 60 80 100 120 630 650 670 690 710 730 750 770 VIN (V) 0 5 10 15 20 25 30 35 40 fsw (kHz) 285 290 295 300 305 310 315 FREQUENCY (KHZ) 630 650 670 690 710 730 750 770 VIN (V) 0 5 10 15 20 25 30 35 40 VIN (V) 0 5 10 15 20 25 30 35 40 CURRENT LIMIT (A) 1.5 1.55 1.6 1.65 1.7 1.75 1.8 1.85 1.9 1.95 TEMPERATURE ( oC) CURRENT LIMIT (A) -40 -20 0 20 40 60 80 100 120 1.5 1.55 1.6 1.65 1.7 1.75 1.8 1.85 1.9 1.95 LM5000 SNVS176D –MAY 2004–REVISED MARCH 2007 www.ti.com TypicalPerformance Characteristics(continued) CurrentLimitvs Temperature CurrentLimitvs VIN Figure9. Figure10. fSW vs.VIN @ FS = Low (-3) fSW vs.VIN @ FS = OPEN (-3) Figure11. Figure12. fSW vs.Temperature @ FS = Low (-3) fSW vs.Temperature @ FS = OPEN (-3) Figure13. Figure14.

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VIN (V) 0 5 10 15 20 25 30 35 40 BYP PIN VOLTAGE (V) 8 125oC 25oC -40oC Gm [Pmho] TEMPERATURE ( oC) -40 -20 0 20 40 60 80 100 120 250 300 350 400 450 500 550 600 -40 -20 0 20 40 60 80 100 120 TEMPERATURE ( oC) 520 540 560 580 600 620 640 fSW (kHz) -40 -20 0 20 40 60 80 100 120 TEMPERATURE ( oC) 1.14 1.18 1.22 1.26 1.30 1.34 1.38 fSW (kHz) LM5000 www.ti.com SNVS176D –MAY 2004–REVISED MARCH 2007 TypicalPerformance Characteristics(continued) fSW vs.Temperature @ FS = Low (-6) fSW vs.Temperature @ FS = OPEN (-6) Figure15. Figure16. ErrorAmp. Transconductance vs Temp. BYP Pin Voltagevs VIN Figure17. Figure18. Copyright© 2004–2007,Texas InstrumentsIncorporated SubmitDocumentationFeedback 7 ProductFolderLinks:LM5000

SNVS176D –MAY 2004–REVISED MARCH 2007 www.ti.com TypicalApplicationDiagrams Figure19. 300 kHz operation,48V output Figure20. 700 kHz operation,48V output

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www.ti.com SNVS176D –MAY 2004–REVISED MARCH 2007 Block Diagram Copyright© 2004–2007,Texas InstrumentsIncorporated SubmitDocumentationFeedback 9 ProductFolderLinks:LM5000

SNVS176D –MAY 2004–REVISED MARCH 2007 www.ti.com BOOST REGULATOR OPERATION The LM5000 utilizesa PWM controlscheme toregulatetheoutputvoltageoverallloadconditions.The operation can bestbe understoodreferringtotheblockdiagramand Figure21.At thestartofeach cycle,theoscillator setsthedriverlogicand turnson theNMOS power deviceconductingcurrentthroughtheinductor,cycle1 of Figure21 (a).Duringthiscycle,the voltageat the COMP pincontrolsthe peak inductorcurrent.The COMP voltagewillincreasewithlargerloadsand decreasewithsmaller.Thisvoltageiscompared withthesummation of the SW volatgeand the ramp compensation.Theramp compensationis used in PWM architecturesto eliminatethesub-harmonicoscillationsthatoccurduringdutycyclesgreaterthan50%. Once thesummation of the ramp compensationand switchvoltageequalsthe COMP voltage,the PWM comparatorresetsthe driver logicturningofftheNMOS power device.The inductorcurrentthenflowsthroughtheoutputdiodetotheload and outputcapacitor,cycle2 ofFigure21 (b).The NMOS power deviceisthensetby theoscillatorattheend of theperiodand currentflowsthroughtheinductoronce again. The LM5000 has dedicatedprotectioncircuitryrunningduringthe normal operationto protectthe IC. The Thermal Shutdown circuitryturnsoffthe NMOS power devicewhen the die temperaturereaches excessive levels.The UVP comparatorprotectsthe NMOS power deviceduringsupplypower startupand shutdown to preventoperationatvoltageslessthantheminimum inputvoltage.The OVP comparatorisused topreventthe outputvoltagefrom risingat no loadsallowingfullPWM operationover allloadconditions.The LM5000 also featuresa shutdown mode. An externalcapacitorsetsthesoftstarttimeby limitingtheerroramp outputrange, as thecapacitorchargesup viaan internal10µA currentsource. The LM5000 isavailableintwo operatingfrequencyranges.The LM5000-3 ispinselectableforeither300kHz (FS Grounded) or 700kHz (FS Open). The LM5000-6 ispin selectableforeither600kHz (FS Grounded) or 1.3MHz (FS Open) Operation Figure21. SimplifiedBoost ConverterDiagram (a)FirstCycle ofOperation(b)Second Cycle Of Operation CONTINUOUS CONDUCTION MODE The LM5000 isa current-mode,PWM regulator.When used as a boostregulatortheinputvoltageissteppedup to a higheroutputvoltage.In continuousconductionmode (when the inductorcurrentnever reacheszero at steadystate),theboostregulatoroperatesintwo cycles. Inthefirstcycleofoperation,shown inFigure21 (a),thetransistorisclosedand thediodeisreversebiased. Energyiscollectedintheinductorand theloadcurrentissuppliedby C OUT .

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:R FB1 = RFB2 x VOUT - 1.259 1.259 VOUT = VIN 1-D , D' = (1-D) = VIN VOUT LM5000 www.ti.com SNVS176D –MAY 2004–REVISED MARCH 2007 The second cycleisshown inFigure21 (b).Duringthiscycle,thetransistorisopen and thediodeisforward biased.The energystoredintheinductoristransferredtotheloadand outputcapacitor. The ratioofthesetwo cyclesdeterminestheoutputvoltage.The outputvoltageisdefinedapproximatelyas: where

• D isthedutycycleoftheswitch
• D and D ′ willbe requiredfordesigncalculations (1) SETTING THE OUTPUT VOLTAGE The outputvoltageissetusingthe feedbackpinand a resistordividerconnectedto the outputas shown in Figure19.The feedbackpinisalwaysat1.259V,so theratioofthefeedbackresistorssetstheoutputvoltage. (2) INTRODUCTION TO COMPENSATION Figure22. (a)Inductorcurrent.(b)Diode current. The LM5000 isa currentmode PWM regulator.The signalflowofthiscontrolscheme has two feedbackloops, one thatsensesswitchcurrentand one thatsensesoutputvoltage. Copyright© 2004–2007,Texas InstrumentsIncorporated SubmitDocumentationFeedback 11 ProductFolderLinks:LM5000

'iL = (in Amps) VIND 2Lfs VINR DSON 0.144 fs L > ( ) D ( ) D D' +1 (in H) Hz1 2S(RC + RO )CC fPC = Hz1fZC = 2SR C C C LM5000 SNVS176D –MAY 2004–REVISED MARCH 2007 www.ti.com To keep a currentprogrammed controlconverterstableabove duty cyclesof 50%, the inductormust meet certaincriteria.The inductor,alongwithinputand outputvoltage,willdeterminetheslopeofthecurrentthrough theinductor(seeFigure22 (a)).Iftheslopeoftheinductorcurrentistoogreat,thecircuitwillbe unstableabove dutycyclesof50%. The LM5000 providesa compensationpin(COMP) tocustomizethevoltageloopfeedback.Itisrecommended thata seriescombinationof R C and C C be used forthe compensationnetwork,as shown inFigure19. The seriescombinationofR C and C C introducespole-zeropairaccordingtothefollowingequations: (3) where

• R O istheoutputimpedance oftheerroramplifier,850kΩ (4) For most applications,performancecan be optimizedby choosingvalueswithintherange5kΩ ≤ R C ≤ 20kΩ and 680pF ≤ C C ≤ 4.7nF. COMPENSATION Thissectionwillpresenta generaldesignproceduretohelpinsurea stableand operationalcircuit.The designs inthisdatasheetare optimizedforparticularrequirements.Ifdifferentconversionsare required,some of the components may need to be changed to ensure stability.Below isa setof generalguidelinesindesigninga stablecircuitforcontinuousconductionoperation(loadsgreaterthan100mA), inmost allcases thiswillprovide forstabilityduringdiscontinuousoperationas well.The power components and theireffectswillbe determined first,thenthecompensationcomponents willbe chosen toproducestability. INDUCTOR SELECTION To ensurestabilityatdutycyclesabove 50%, theinductormust have some minimum valuedeterminedby the minimum inputvoltageand themaximum outputvoltage.Thisequationis: where
• fsistheswitchingfrequency
• D isthedutycycle
• R DSON istheON resistanceoftheinternalswitch (5) Thisequationisonlygood fordutycyclesgreaterthan50% (D>0.5). (6) The inductorripplecurrentisimportantfora few reasons.One reasonisbecause thepeak switchcurrentwillbe theaverageinductorcurrent(inputcurrent)plusΔiL.Care must be takentomake surethattheswitchwillnot reach itscurrentlimitduringnormal operation.The inductormust alsobe sizedaccordingly.Itshouldhave a saturationcurrentratinghigherthanthepeak inductorcurrentexpected.The outputvoltagerippleisalsoaffected by thetotalripplecurrent. DC GAIN AND OPEN-LOOP GAIN Sincethecontrolstageoftheconverterformsa completefeedbackloopwiththepower components,itformsa closed-loopsystem thatmust be stabilizedtoavoidpositivefeedbackand instability.A valueforopen-loopDC gain willbe required,from which you can calculate,or place,polesand zeros to determinethe crossover frequencyand the phase margin.A highphase margin (greaterthan 45°) isdesiredforthe beststabilityand transientresponse.For thepurposeofstabilizingtheLM5000, choosinga crossoverpointwellbelow where the righthalfplanezeroislocatedwillensuresufficientphase margin.A discussionoftherighthalfplanezeroand checkingthecrossoverusingtheDC gainwillfollow.

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fZC = 1 2SC C R C (in Hz) fPC = 1 2S(RC + RO )CC (in Hz) (in Hz)RHPzero = VOUT (D')2 2S,LOAD L fZ1 = 1 2SR ESR C OUT (in Hz) fP1 = 1 2S(RESR + RL)COUT (in Hz) LM5000 www.ti.com SNVS176D –MAY 2004–REVISED MARCH 2007 OUTPUT CAPACITOR SELECTION The choiceofoutputcapacitorsissomewhat more arbitrary.Itisrecommended thatlow ESR (EquivalentSeries Resistance,denoted R ESR ) capacitorsbe used such as ceramic,polymer electrolytic,or low ESR tantalum. HigherESR capacitorsmay be used butwillrequiremore compensationwhich willbe explainedlateron inthe section.The ESR isalsoimportantbecause itdeterminestheoutputvoltagerippleaccordingtotheapproximate equation: ΔVOUT ≊ 2ΔiLR ESR (inVolts) (7) Afterchoosingtheoutputcapacitoryou can determinea pole-zeropairintroducedintothecontrolloopby the followingequations: (8) where

• R L istheminimum loadresistancecorrespondingtothemaximum loadcurrent (9) The zerocreatedby theESR oftheoutputcapacitorisgenerallyveryhighfrequencyiftheESR issmall.Iflow ESR capacitorsare used itcan be neglected.IfhigherESR capacitorsare used see the HIGH OUTPUT CAPACITOR ESR COMPENSATION section. RIGHT HALF PLANE ZERO A currentmode controlboostregulatorhas an inherentrighthalfplanezero(RHP zero).Thiszerohas theeffect ofa zerointhegainplot,causingan imposed +20dB/decade on therolloff,buthas theeffectofa poleinthe phase, subtractinganother90° in the phase plot.This can cause undesirableeffectsifthe controlloop is influencedby thiszero.To ensuretheRHP zerodoes notcause instabilityissues,thecontrolloopshouldbe designedtohave a bandwidthof½ thefrequencyoftheRHP zeroorless.Thiszerooccursata frequencyof: where
• ILOAD isthemaximum loadcurrent (10) SELECTING THE COMPENSATION COMPONENTS The firststepinselectingthecompensationcomponents R C and C C istoseta dominantlow frequencypolein the controlloop.Simply choose valuesforR C and C C withinthe ranges givenin the INTRODUCTION TO COMPENSATION sectiontosetthispoleinthearea of10Hz to100Hz. The frequencyofthepolecreatedis determinedby theequation: where
• R O istheoutputimpedance oftheerroramplifier,850kΩ (11) Since R C isgenerallymuch lessthan R O , itdoes not have much effecton the above equationand can be neglecteduntila valueischosen tosetthezerofZC .fZC iscreatedtocanceloutthepolecreatedby theoutput capacitor,fP1.The outputcapacitorpolewillshiftwithdifferentloadcurrentsas shown by theequation,so setting thezeroisnotexact.Determinetherange offP1 overtheexpectedloadsand thensetthezerofZC toa point approximatelyinthemiddle.The frequencyofthiszeroisdeterminedby: (12) Copyright© 2004–2007,Texas InstrumentsIncorporated SubmitDocumentationFeedback 13 ProductFolderLinks:LM5000

m1 # VINR DSON L (in V/s) n = 1+ 2mc m1 (no unit) Leff = L (D')2 Zc (in rad/s)2fs nD'# ADC(DB) = 20log10 {[(ZcLeff)// RL]//RL} (in dB) R FB1 + RFB2 R FB2 ( ) gm R O D' R DSON fPC2 = 1 2SC C2 (RC //RO ) (in Hz) LM5000 SNVS176D –MAY 2004–REVISED MARCH 2007 www.ti.com Now R C can be chosen withtheselectedvalueforC C .Check tomake surethatthepolefPC isstillinthe10Hz to 100Hz range,change each valueslightlyifneeded toensurebothcomponent valuesare intherecommended range.Aftercheckingthedesignattheend ofthissection,thesevaluescan be changed a littlemore tooptimize performanceifdesired.Thisisbestdone inthelabon a bench,checkingtheloadstepresponsewithdifferent valuesuntiltheringingand overshooton theoutputvoltageattheedge oftheloadstepsisminimal.Thisshould produce a stable,highperformancecircuit.For improvedtransientresponse,highervaluesof R C (withinthe range ofvalues)shouldbe chosen.Thiswillimprovetheoverallbandwidthwhich makes theregulatorrespond more quicklytotransients.Ifmore detailisrequired,orthemost optimalperformanceisdesired,refertoa more indepthdiscussionofcompensatingcurrentmode DC/DC switchingregulators. HIGH OUTPUT CAPACITOR ESR COMPENSATION When usingan outputcapacitorwitha highESR value,orjusttoimprovetheoverallphase marginofthecontrol loop,anotherpolemay be introducedtocancelthezerocreatedby theESR. Thisisaccomplishedby adding anothercapacitor,C C2 ,directlyfromthecompensationpinVC toground,inparallelwiththeseriescombinationof R C and C C .The poleshouldbe placedatthesame frequencyas fZ1,theESR zero.The equationforthispole follows: (13) To ensurethisequationisvalid,and thatC C2 can be used withoutnegativelyimpactingtheeffectsofR C and C C , fPC2 must be greaterthan10fPC . CHECKING THE DESIGN The finalstepistocheck thedesign.Thisistoensurea bandwidthof½ or lessofthefrequencyoftheRHP zero.Thisisdone by calculatingtheopen-loopDC gain,ADC .Afterthisvalueisknown, you can calculatethe crossovervisuallyby placinga −20dB/decadeslopeateach pole,and a +20dB/decadeslopeforeach zero.The pointatwhichthegainplotcrossesunitygain,or0dB, isthecrossoverfrequency.Ifthecrossoverfrequencyis atlessthan½ theRHP zero,thephase marginshouldbe highenough forstability.The phase margincan also be improvedsome by addingC C2 as discussedearlierinthesection.The equationforADC isgivenbelow with additionalequationsrequiredforthecalculation: (14) (15) (16) (17) mc ≊ 0.072fs(inA/s) (18) where

• R L istheminimum loadresistance
• VIN isthemaximum inputvoltage
• R DSON isthevaluechosen fromthegraph"RDSON vs.VIN "intheTypicalPerformanceCharacteristics section (19) SWITCH VOLTAGE LIMITS In a flybackregulator,the maximum steady-statevoltageappearingat the switch,when itisoff,issetby the transformerturnsratio,N, theoutputvoltage,VOUT ,and themaximum inputvoltage,VIN (Max): VSW(OFF) = VIN (Max)+ (VOUT +VF)/N where
• VF istheforwardbiasedvoltageoftheoutputdiode,and istypically0.5VforSchottkydiodesand 0.8Vfor ultra-fastrecoverydiodes (20)

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www.ti.com SNVS176D –MAY 2004–REVISED MARCH 2007 Incertaincircuits,thereexistsa voltagespike,VLL,superimposedon topofthesteady-statevoltage.Usually, thisvoltagespikeiscaused by thetransformerleakageinductanceand/ortheoutputrectifierrecoverytime.To “clamp” the voltageat the switchfrom exceedingitsmaximum value,a transientsuppressorinserieswitha diodeisinsertedacrossthetransformerprimary. Ifpoorcircuitlayouttechniquesareused,negativevoltagetransientsmay appearon theSwitchpin.Applyinga negativevoltage(withrespectto the IC'sground)to any monolithicIC pin causes erraticand unpredictable operationofthatIC.ThisholdstruefortheLM5000 IC as well.When used ina flybackregulator,thevoltageat theSwitchpincan go negativewhen theswitchturnson.The “ringing”voltageattheswitchpiniscaused by the output diode capacitanceand the transformerleakage inductanceforming a resonant circuitat the secondary(ies).The resonantcircuitgeneratesthe “ringing” voltage,which gets reflectedback throughthe transformerto the switchpin.There are two common methods to avoidthisproblem.One isto add an RC snubberaround theoutputrectifier(s).The valuesoftheresistorand thecapacitormust be chosen so thatthe voltageattheSwitchpindoes notdrop below −0.4V.The resistormay range invaluebetween 10Ω and 1 kΩ, and thecapacitorwillvaryfrom0.001μF to0.1μF. Adding a snubberwill(slightly)reducetheefficiencyofthe overallcircuit. The othermethod toreduceor eliminatethe“ringing” istoinserta Schottkydiodeclamp between theSW pin and thePGND pin.The reversevoltageratingofthediodemust be greaterthantheswitchoffvoltage. OUTPUT VOLTAGE LIMITATIONS The maximum outputvoltageof a boost regulatoristhe maximum switchvoltageminus a diode drop.In a flybackregulator,themaximum outputvoltageisdeterminedby theturnsratio,N, and thedutycycle,D, by the equation: VOUT ≈ N × VIN × D/(1− D) (21) The dutycycleofa flybackregulatorisdeterminedby thefollowingequation: (22) Theoretically,themaximum outputvoltagecan be as largeas desired— justkeep increasingtheturnsratioofthe transformer.However, thereexistssome physicallimitationsthatpreventthe turnsratio,and thusthe output voltage,from increasingto infinity.The physicallimitationsare capacitancesand inductancesinthe LM5000 switch,theoutputdiode(s),and thetransformer— such as reverserecoverytimeoftheoutputdiode(mentioned above). INPUT LINE CONDITIONING A small,low-passRC filtershouldbe used attheinputpinoftheLM5000 iftheinputvoltagehas an unusually largeamount oftransientnoise.Additionally,theRC filtercan reducethedissipationwithinthedevicewhen the inputvoltageishigh. FlybackRegulatorOperation The LM5000 isideallysuitedforuse intheflybackregulatortopology.The flybackregulatorcan producea single outputvoltage,ormultipleoutputvoltages. The operationof a flybackregulatorisas follows:When the switchison, currentflowsthroughthe primary windingofthetransformer,T1,storingenergyinthemagneticfieldofthetransformer.Note thattheprimaryand secondarywindingsareoutofphase,so no currentflowsthroughthesecondarywhen currentflowsthroughthe primary.When theswitchturnsoff,themagneticfieldcollapses,reversingthevoltagepolarityoftheprimaryand secondarywindings.Now rectifierD5 isforwardbiasedand currentflowsthroughit,releasingtheenergystored inthetransformer.Thisproducesvoltageattheoutput. The outputvoltageiscontrolledby modulatingthepeak switchcurrent.Thisisdone by feedingback a portionof theoutputvoltagetotheerroramp, which amplifiesthedifferencebetween thefeedbackvoltageand a 1.259V reference.The erroramp outputvoltageiscompared toa ramp voltageproportionaltotheswitchcurrent(i.e., inductorcurrentduringtheswitchon time).The comparatorterminatestheswitchon timewhen thetwo voltages areequal,therebycontrollingthepeak switchcurrenttomaintaina constantoutputvoltage. Copyright© 2004–2007,Texas InstrumentsIncorporated SubmitDocumentationFeedback 15 ProductFolderLinks:LM5000

SNVS176D –MAY 2004–REVISED MARCH 2007 www.ti.com Figure23. LM5000 FlybackConverter

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www.ti.com SNVS176D –MAY 2004–REVISED MARCH 2007 ITEM PART NUMBER DESCRIPTION VALUE C 1 C4532X7R2A105MT Capacitor,CER, TDK 1µ,100V C 2 C4532X7R2A105MT Capacitor,CER, TDK 1µ,100V C 3 C1206C224K5RAC Capacitor,CER, KEMET 0.22µ,50V C 4 C1206C104K5RAC Capacitor,CER, KEMET 0.1µ,50V C 5 C1206C104K5RAC Capacitor,CER, KEMET 0.1µ,50V C 6 C1206C101K1GAC Capacitor,CER, KEMET 100p,100V C 7 C1206C104K5RAC Capacitor,CER, KEMET 0.1µ,50V C 8 C4532X7S0G686M Capacitor,CER, TDK 68µ,4V C 9 C4532X7S0G686M Capacitor,CER, TDK 68µ,4V C 10 C1206C221K1GAC Capacitor,CER, KEMET 220p,100V C 11 C1206C102K5RAC Capacitor,CER, KEMET 1000p,500V D 1 BZX84C10-NSA Central,10V Zener,SOT-23 D 2 CMZ5930B-NSA Central,16V Zener,SMA D 3 CMPD914-NSA Central,Switching,SOT-23 D 4 CMPD914-NSA Central,Switching,SOT-23 D 5 CMSH3-40L-NSA Central,Schottky,SMC T 1 A0009-A Coilcraft,Transformer R 1 CRCW12064992F Resistor 49.9K R 2 CRCW12061001F Resistor 1K R 3 CRCW12061002F Resistor 10K R 4 CRCW12066191F Resistor 6.19K R 5 CRCW120610R0F Resistor 10 R 6 CRCW12062003F Resistor 200K R 7 CRCW12061002F Resistor 10K Q 1 CXT5551-NSA Central,NPN, 180V U 1 LM5000-3 Regulator,TI Copyright© 2004–2007,Texas InstrumentsIncorporated SubmitDocumentationFeedback 17 ProductFolderLinks:LM5000

www.ti.com 11-Nov-2025 PACKAGING INFORMATION Orderable part number Status (1) Material type (2) Package | Pins Package qty | Carrier RoHS (3) Lead finish/ Ball material (4) MSL rating/ Peak reflow (5) Op temp (°C) Part marking (6) LM5000-3MTC/NOPB Active Production TSSOP (PW) | 16 92 | TUBE Yes SN Level-1-260C-UNLIM -40 to 125 LM5000 3MTC LM5000-3MTC/NOPB.A Active Production TSSOP (PW) | 16 92 | TUBE Yes SN Level-1-260C-UNLIM -40 to 125 LM5000 3MTC LM5000-3MTC/NOPB.B Active Production TSSOP (PW) | 16 92 | TUBE Yes SN Level-1-260C-UNLIM -40 to 125 LM5000 3MTC LM5000-3MTCX/NOPB Active Production TSSOP (PW) | 16 2500 | LARGE T&R Yes SN Level-1-260C-UNLIM -40 to 125 LM5000 3MTC LM5000-3MTCX/NOPB.A Active Production TSSOP (PW) | 16 2500 | LARGE T&R Yes SN Level-1-260C-UNLIM -40 to 125 LM5000 3MTC LM5000-3MTCX/NOPB.B Active Production TSSOP (PW) | 16 2500 | LARGE T&R Yes SN Level-1-260C-UNLIM -40 to 125 LM5000 3MTC LM5000SD-3/NOPB Active Production WSON (NHQ) | 16 1000 | SMALL T&R Yes SN Level-1-260C-UNLIM -40 to 125 5000-3 LM5000SD-3/NOPB.A Active Production WSON (NHQ) | 16 1000 | SMALL T&R Yes SN Level-1-260C-UNLIM -40 to 125 5000-3 LM5000SD-3/NOPB.B Active Production WSON (NHQ) | 16 1000 | SMALL T&R Yes SN Level-1-260C-UNLIM -40 to 125 5000-3 LM5000SD-6/NOPB Active Production WSON (NHQ) | 16 1000 | SMALL T&R Yes SN Level-1-260C-UNLIM -40 to 125 5000-6 LM5000SD-6/NOPB.A Active Production WSON (NHQ) | 16 1000 | SMALL T&R Yes SN Level-1-260C-UNLIM -40 to 125 5000-6 LM5000SD-6/NOPB.B Active Production WSON (NHQ) | 16 1000 | SMALL T&R Yes SN Level-1-260C-UNLIM -40 to 125 5000-6 LM5000SDX-3/NOPB Active Production WSON (NHQ) | 16 4500 | LARGE T&R Yes SN Level-1-260C-UNLIM -40 to 125 5000-3 LM5000SDX-3/NOPB.A Active Production WSON (NHQ) | 16 4500 | LARGE T&R Yes SN Level-1-260C-UNLIM -40 to 125 5000-3 LM5000SDX-3/NOPB.B Active Production WSON (NHQ) | 16 4500 | LARGE T&R Yes SN Level-1-260C-UNLIM -40 to 125 5000-3 (1) Status: For more details on status, see our product life cycle. (2) Material type: When designated, preproduction parts are prototypes/experimental devices, and are not yet approved or released for full production. Testing and final process, including without limitation quality assurance, reliability performance testing, and/or process qualification, may not yet be complete, and this item is subject to further changes or possible discontinuation. If available for ordering, purchases will be subject to an additional waiver at checkout, and are intended for early internal evaluation purposes only. These items are sold without warranties of any kind. (3) RoHS values: Yes, No, RoHS Exempt. See the TI RoHS Statement for additional information and value definition. (4) Lead finish/Ball material: Parts may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead finish/Ball material values may wrap to two lines if the finish value exceeds the maximum column width. Addendum-Page 1

www.ti.com 11-Nov-2025 (5) MSL rating/Peak reflow: The moisture sensitivity level ratings and peak solder (reflow) temperatures. In the event that a part has multiple moisture sensitivity ratings, only the lowest level per JEDEC standards is shown. Refer to the shipping label for the actual reflow temperature that will be used to mount the part to the printed circuit board. (6) Part marking: There may be an additional marking, which relates to the logo, the lot trace code information, or the environmental category of the part. Multiple part markings will be inside parentheses. Only one part marking contained in parentheses and separated by a "~" will appear on a part. If a line is indented then it is a continuation of the previous line and the two combined represent the entire part marking for that device. Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals. TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release. In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis. Addendum-Page 2

PACKAGE MATERIALS INFORMATION www.ti.com 10-Aug-2026 TAPE AND REEL INFORMATION Reel Width (W1) REEL DIMENSIONS A0B0K0WDimension designed to accommodate the component lengthDimension designed to accommodate the component thicknessOverall width of the carrier tapePitch between successive cavity centersDimension designed to accommodate the component width TAPE DIMENSIONSK0 P1B0WA0Cavity QUADRANT ASSIGNMENTS FOR PIN 1 ORIENTATION IN TAPE Pocket QuadrantsSprocket HolesQ1Q1Q2Q2Q3Q3Q4Q4User Direction of Feed P1ReelDiameter *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Reel Diameter (mm) Reel Width W1 (mm) (mm) (mm) (mm) (mm) W (mm) Pin1 Quadrant Pack Materials-Page 1

PACKAGE MATERIALS INFORMATION www.ti.com 10-Aug-2026 TAPE AND REEL BOX DIMENSIONS Width (mm) W LH *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) LM5000-3MTCX/NOPB TSSOP PW 16 2500 367.0 367.0 35.0 LM5000SD-3/NOPB WSON NHQ 16 1000 208.0 191.0 35.0 LM5000SD-6/NOPB WSON NHQ 16 1000 208.0 191.0 35.0 LM5000SDX-3/NOPB WSON NHQ 16 4500 367.0 367.0 35.0 Pack Materials-Page 2

PACKAGE MATERIALS INFORMATION www.ti.com 10-Aug-2026 TUBE L - Tube length T - Tube height W - Tube width B - Alignment groove width *All dimensions are nominal Device Package Name Package Type Pins SPQ L (mm) W (mm) T (µm) B (mm) LM5000-3MTC/NOPB PW TSSOP 16 92 495 8 2514.6 4.06 LM5000-3MTC/NOPB.A PW TSSOP 16 92 495 8 2514.6 4.06 LM5000-3MTC/NOPB.B PW TSSOP 16 92 495 8 2514.6 4.06 Pack Materials-Page 3

www.ti.com SDA16A (Rev A)

www.ti.com PACKAGE OUTLINE C 14X 0.65 4.55 16X 0.30 0.17 6.6

6.2 TYP

1.2 MAX

0.15 0.05 0.25 GAGE PLANE 0 -8 4X (0 -12 ) B 4.5 4.3 NOTE 4 A 5.1 4.9 NOTE 3 0.75 0.50 (0.15) TYP TSSOP - 1.2 mm max heightPW0016A SMALL OUTLINE PACKAGE 4220204/B 12/2023

0.1 C A B

0.1 C NOTES: 1. All linear dimensions are in millimeters. Any dimensions in parenthesis are for reference only. Dimensioning and tolerancing per ASME Y14.5M. 2. This drawing is subject to change without notice. 3. This dimension does not include mold flash, protrusions, or gate burrs. Mold flash, protrusions, or gate burrs shall not exceed 0.15 mm per side. 4. This dimension does not include interlead flash. Interlead flash shall not exceed 0.25 mm per side. 5. Reference JEDEC registration MO-153. SEATING PLANE A 20 DETAIL A TYPICAL SCALE 2.500

www.ti.com EXAMPLE BOARD LAYOUT

0.05 MAX

0.05 MIN

16X (1.5) 16X (0.45) 14X (0.65) (5.8) (R0.05) TYP TSSOP - 1.2 mm max heightPW0016A SMALL OUTLINE PACKAGE 4220204/B 12/2023 NOTES: (continued) 6. Publication IPC-7351 may have alternate designs. 7. Solder mask tolerances between and around signal pads can vary based on board fabrication site. LAND PATTERN EXAMPLE EXPOSED METAL SHOWN SCALE: 10X SYMM SYMM 8 9 15.000 METALSOLDER MASK OPENING METAL UNDER SOLDER MASK SOLDER MASK OPENING EXPOSED METALEXPOSED METAL SOLDER MASK DETAILS NON-SOLDER MASK DEFINED (PREFERRED) SOLDER MASK DEFINED

www.ti.com EXAMPLE STENCIL DESIGN 16X (1.5) 16X (0.45) 14X (0.65) (5.8) (R0.05) TYP TSSOP - 1.2 mm max heightPW0016A SMALL OUTLINE PACKAGE 4220204/B 12/2023 NOTES: (continued) 8. Laser cutting apertures with trapezoidal walls and rounded corners may offer better paste release. IPC-7525 may have alternate design recommendations. 9. Board assembly site may have different recommendations for stencil design. SOLDER PASTE EXAMPLE BASED ON 0.125 mm THICK STENCIL SCALE: 10X SYMM SYMM 8 9

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