lm317

LM317L

3-TerminalAdjustableRegulator

GeneralDescription

TheLM317Lisanadjustable3-terminalpositivevoltageregulatorcapableofsupplying100mAovera1.2Vto37Voutputrange.Itisexceptionallyeasytouseandrequiresonlytwoexternalresistorstosettheoutputvoltage.Further,bothlineandloadregulationarebetterthanstandardfixedregulators.Also,theLM317Lisavailablepackagedinastan-dardTO-92transistorpackagewhichiseasytouse.

Inadditiontohigherperformancethanfixedregulators,theLM317Loffersfulloverloadprotection.Includedonthechiparecurrentlimit,thermaloverloadprotectionandsafeareaprotection.Alloverloadprotectioncircuitryremainsfullyfunc-tionaleveniftheadjustmentterminalisdisconnected.

Normally,nocapacitorsareneededunlessthedeviceissitu-atedmorethan6inchesfromtheinputfiltercapacitorsinwhichcaseaninputbypassisneeded.Anoptionaloutputcapacitorcanbeaddedtoimprovetransientresponse.Theadjustmentterminalcanbebypassedtoachieveveryhighripplerejectionratioswhicharedifficulttoachievewithstan-dard3-terminalregulators.

Besidesreplacingfixedregulators,theLM317Lisusefulinawidevarietyofotherapplications.Sincetheregulatoris“floating”andseesonlytheinput-to-outputdifferentialvolt-age,suppliesofseveralhundredvoltscanberegulatedaslongasthemaximuminput-to-outputdifferentialisnotex-ceeded.

Also,itmakesanespeciallysimpleadjustableswitchingregulator,aprogrammableoutputregulator,orbyconnectingafixedresistorbetweentheadjustmentandoutput,theLM317Lcanbeusedasaprecisioncurrentregulator.Sup-plieswithelectronicshutdowncanbeachievedbyclampingtheadjustmentterminaltogroundwhichprogramstheout-putto1.2Vwheremostloadsdrawlittlecurrent.

TheLM317LisavailableinastandardTO-92transistorpackage,theSO-8package,and6-BumpmicroSMDpack-age.TheLM317Lisratedforoperationovera−25˚Cto125˚Crange.

Features

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Adjustableoutputdownto1.2VGuaranteed100mAoutputcurrentLineregulationtypically0.01%VLoadregulationtypically0.1%

Currentlimitconstantwithtemperature

EliminatestheneedtostockmanyvoltagesStandard3-leadtransistorpackage80dBripplerejection

AvailableinTO-92,SO-8,or6-BumpmicroSMDpackage

nOutputisshortcircuitprotected

nSeeAN-1112formicroSMDconsiderations

ConnectionDiagrams

TO-92Plasticpackage

8-PinSOIC

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TopView

©2000NationalSemiconductorCorporationDS009064www.national.com

LM317LConnectionDiagrams

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microSMDLaserMark

6-BumpmicroSMD

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*NC=NotInternallyconnected.

TopView

(BumpSideDown)

PackageTO-928-PinSOIC6-BumpmicroSMD

PartNumberLM317LZLM317LM

*LM317LIBP*LM317LIBPX

PackageMarking

LM317LZLM317LM

––

MediaTransport1.8kUnitsperBox

Rails

250UnitsTapeandReel3kUnitsTapeandReel

NSCDrawing

Z03AM08ABPA06HPA

Note:ThemicroSMDpackagemarkingisasingledigitmanufacturingDateCodeonly.

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LM317LAbsoluteMaximumRatings(Note1)

IfMilitary/Aerospacespecifieddevicesarerequired,pleasecontacttheNationalSemiconductorSalesOffice/Distributorsforavailabilityandspecifications.PowerDissipation

Input-OutputVoltageDifferentialOperatingJunctionTemperatureRange

InternallyLimited

40V−40˚Cto+125˚C

StorageTemperatureLeadTemperature

(Soldering,4seconds)

OutputisShortCircuitProtectedESDratingtobedetermined.

−55˚Cto+150˚C

260˚C

ElectricalCharacteristics(Note2)

Parameter

LineRegulationLoadRegulationThermalRegulationAdjustmentPinCurrentAdjustmentPinCurrentChange

ReferenceVoltageLineRegulationLoadRegulationTemperatureStabilityMinimumLoadCurrentCurrentLimit

RmsOutputNoise,%ofVOUTRippleRejectionRatioLong-TermStabilityThermalResistanceJunctiontoAmbient

5mA≤IL≤100mA

3V≤(VIN−VOUT)≤40V,P≤625mW3V≤(VIN−VOUT)≤40V,(Note4)5mA≤IOUT≤100mA,P≤625mW

3V≤(VIN−VOUT)≤40V,IL≤20mA(Note3)5mA≤IOUT≤100mA,(Note3)TMIN≤TJ≤TMax(VIN−VOUT)≤40V3V≤(VIN−VOUT)≤15V3V≤(VIN−VOUT)≤13V(VIN−VOUT)=40V

TJ=25˚C,10Hz≤f≤10kHzVOUT=10V,f=120Hz,CADJ=0CADJ=10µF

TJ=125˚C,1000HoursZPackage0.4\"LeadsZPackage0.125LeadsSO-8Package6-BumpmicroSMD

ThermalRatingofSOPackage

6610025

0.020.30.653.51.5200500.00365800.3180160165290165

152.5300150

mAmA%dBdB%˚C/W˚C/W˚C/W˚C/W˚C/W

0.071.5

%/V%%mA

1.20

1.25

1.30

V

Conditions

TJ=25˚C,3V≤(VIN−VOUT)≤40V,IL≤20mA(Note3)TJ=25˚C,5mA≤IOUT≤IMAX,(Note3)TJ=25˚C,10msPulse

Min

Typ0.010.10.04500.2

Max0.040.50.21005

Units%/V%%/WµAµA

Note1:“AbsoluteMaximumRatings”indicatelimitsbeyondwhichdamagetothedevicemayoccur.OperatingRatingsindicateconditionsforwhichthedeviceisfunctional,butdonotguaranteespecificperformancelimits.

Note2:Unlessotherwisenoted,thesespecificationsapply:−25˚C≤Tj≤125˚CfortheLM317L;VIN−VOUT=5VandIOUT=40mA.Althoughpowerdissipationisinternallylimited,thesespecificationsareapplicableforpowerdissipationsupto625mW.IMAXis100mA.

Note3:Regulationismeasuredatconstantjunctiontemperature,usingpulsetestingwithalowdutycycle.Changesinoutputvoltageduetoheatingeffectsarecov-eredunderthespecificationforthermalregulation.

Note4:ThermalresistanceoftheTO-92packageis180˚C/Wjunctiontoambientwith0.4\"leadsfromaPCboardand160˚C/Wjunctiontoambientwith0.125\"leadlengthtoPCboard.

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LM317LTypicalPerformanceCharacteristics

LoadRegulation

(Outputcapacitor=0µFunlessotherwisenoted.)CurrentLimit

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AdjustmentCurrentDropoutVoltage

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ReferenceVoltageTemperatureStability

MinimumOperatingCurrent

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LM317LTypicalPerformanceCharacteristics

RippleRejection

(Outputcapacitor=0µFunlessotherwisenoted.)(Continued)RippleRejection

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OutputImpedanceLineTransientResponse

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LoadTransientResponseThermalRegulation

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LM317LApplicationHints

Inoperation,theLM317Ldevelopsanominal1.25Vrefer-encevoltage,VREF,betweentheoutputandadjustmentter-minal.ThereferencevoltageisimpressedacrossprogramresistorR1and,sincethevoltageisconstant,aconstantcurrentI1thenflowsthroughtheoutputsetresistorR2,giv-inganoutputvoltageof

tween500pFand5000pF.A1µFsolidtantalum(or25µFaluminumelectrolytic)ontheoutputswampsthiseffectandinsuresstability.LoadRegulation

TheLM317Liscapableofprovidingextremelygoodloadregulationbutafewprecautionsareneededtoobtainmaxi-mumperformance.Thecurrentsetresistorconnectedbe-tweentheadjustmentterminalandtheoutputterminal(usu-ally240Ω)shouldbetieddirectlytotheoutputoftheregulatorratherthanneartheload.Thiseliminateslinedropsfromappearingeffectivelyinserieswiththereferenceanddegradingregulation.Forexample,a15Vregulatorwith0.05Ωresistancebetweentheregulatorandloadwillhavealoadregulationduetolineresistanceof0.05ΩxIL.Ifthesetresistorisconnectedneartheloadtheeffectivelineresis-tancewillbe0.05Ω(1+R2/R1)orinthiscase,11.5timesworse.

Sincethe100µAcurrentfromtheadjustmentterminalrepre-sentsanerrorterm,theLM317LwasdesignedtominimizeIADJandmakeitveryconstantwithlineandloadchanges.Todothis,allquiescentoperatingcurrentisreturnedtotheoutputestablishingaminimumloadcurrentrequirement.Ifthereisinsufficientloadontheoutput,theoutputwillrise.

Figure2showstheeffectofresistancebetweentheregula-torand240Ωsetresistor.

WiththeTO-92package,itiseasytominimizetheresis-tancefromthecasetothesetresistor,byusingtwoseparateleadstotheoutputpin.ThegroundofR2canbereturnednearthegroundoftheloadtoprovideremotegroundsens-ingandimproveloadregulation.

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FIGURE1.

ExternalCapacitors

Aninputbypasscapacitorisrecommendedincasetheregu-latorismorethan6inchesawayfromtheusuallargefiltercapacitor.A0.1µFdiscor1µFsolidtantalumontheinputissuitableinputbypassingforalmostallapplications.Thede-viceismoresensitivetotheabsenceofinputbypassingwhenadjustmentoroutputcapacitorsareused,buttheabovevalueswilleliminatethepossibilityofproblems.

TheadjustmentterminalcanbebypassedtogroundontheLM317Ltoimproveripplerejectionandnoise.Thisbypasscapacitorpreventsrippleandnoisefrombeingamplifiedastheoutputvoltageisincreased.Witha10µFbypasscapaci-tor80dBripplerejectionisobtainableatanyoutputlevel.In-creasesover10µFdonotappreciablyimprovetheripplere-jectionatfrequenciesabove120Hz.Ifthebypasscapacitorisused,itissometimesnecessarytoincludeprotectiondi-odestopreventthecapacitorfromdischargingthroughinter-nallowcurrentpathsanddamagingthedevice.

Ingeneral,thebesttypeofcapacitorstouseissolidtanta-lum.Solidtantalumcapacitorshavelowimpedanceevenathighfrequencies.Dependinguponcapacitorconstruction,ittakesabout25µFinaluminumelectrolytictoequal1µFsolidtantalumathighfrequencies.Ceramiccapacitorsarealsogoodathighfrequencies;butsometypeshavealargede-creaseincapacitanceatfrequenciesaround0.5MHz.Forthisreason,a0.01µFdiscmayseemtoworkbetterthana0.1µFdiscasabypass.

AlthoughtheLM317Lisstablewithnooutputcapacitors,likeanyfeedbackcircuit,certainvaluesofexternalcapacitancecancauseexcessiveringing.Thisoccurswithvaluesbe-www.national.com

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FIGURE2.RegulatorwithLineResistance

inOutputLead

ThermalRegulation

WhenpowerisdissipatedinanIC,atemperaturegradientoccursacrosstheICchipaffectingtheindividualICcircuitcomponents.WithanICregulator,thisgradientcanbeespe-ciallyseveresincepowerdissipationislarge.Thermalregu-lationistheeffectofthesetemperaturegradientsonoutputvoltage(inpercentageoutputchange)perwattofpowerchangeinaspecifiedtime.Thermalregulationerrorisinde-pendentofelectricalregulationortemperaturecoefficient,andoccurswithin5msto50msafterachangeinpowerdis-sipation.ThermalregulationdependsonIClayoutaswellaselectricaldesign.Thethermalregulationofavoltageregula-torisdefinedasthepercentagechangeofVOUT,perwatt,withinthefirst10msafterastepofpowerisapplied.TheLM317Lspecificationis0.2%/W,maximum.

IntheThermalRegulationcurveatthebottomoftheTypicalPerformanceCharacteristicspage,atypicalLM317L’sout-putchangesonly7mV(or0.07%ofVOUT=−10V)whena1Wpulseisappliedfor10ms.Thisperformanceisthuswellinsidethespecificationlimitof0.2%/Wx1W=0.2%maxi-mum.Whenthe1Wpulseisended,thethermalregulationagainshowsa7mVchangeasthegradientsacrosstheLM317Lchipdieout.Notethattheloadregulationerrorofabout14mV(0.14%)isadditionaltothethermalregulationerror.

LM317LApplicationHints

ProtectionDiodes

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WhenexternalcapacitorsareusedwithanyICregulatoritissometimesnecessarytoaddprotectiondiodestopreventthecapacitorsfromdischargingthroughlowcurrentpointsintotheregulator.Most10µFcapacitorshavelowenoughin-ternalseriesresistancetodeliver20Aspikeswhenshorted.Althoughthesurgeisshort,thereisenoughenergytodam-agepartsoftheIC.

Whenanoutputcapacitorisconnectedtoaregulatorandtheinputisshorted,theoutputcapacitorwilldischargeintotheoutputoftheregulator.Thedischargecurrentdependsonthevalueofthecapacitor,theoutputvoltageoftheregu-lator,andtherateofdecreaseofVIN.IntheLM317L,thisdis-

chargepathisthroughalargejunctionthatisabletosustaina2Asurgewithnoproblem.Thisisnottrueofothertypesofpositiveregulators.Foroutputcapacitorsof25µForless,theLM317L’sballastresistorsandoutputstructurelimitthepeakcurrenttoalowenoughlevelsothatthereisnoneedtouseaprotectiondiode.

Thebypasscapacitorontheadjustmentterminalcandis-chargethroughalowcurrentjunction.Dischargeoccurswheneithertheinputoroutputisshorted.InternaltotheLM317Lisa50Ωresistorwhichlimitsthepeakdischargecurrent.Noprotectionisneededforoutputvoltagesof25Vorlessand10µFcapacitance.Figure3showsanLM317Lwithprotectiondiodesincludedforusewithoutputsgreaterthan25Vandhighvaluesofoutputcapacitance.

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D1protectsagainstC1D2protectsagainstC2

FIGURE3.RegulatorwithProtectionDiodes

LM317LmicroSMDLightSensitivity

ExposingtheLM317LmicroSMDpackagetobrightsunlightmaycausetheVREFtodrop.Inanormalofficeenvironmentoffluorescentlightingtheoutputisnotaffected.TheLM317

microSMDdoesnotsustainpermanentdamagefromlightexposure.RemovingthelightsourcewillcauseLM317L’sVREFtorecovertothepropervalue.

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LM317LSchematicDiagram

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LM317LTypicalApplications

DigitallySelectedOutputs

HighGainAmplifier

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*SetsmaximumVOUT

PrecisionCurrentLimiter

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12≤R1≤240

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SlowTurn-On15VRegulator

AdjustableRegulatorwithImprovedRippleRejection

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†Solidtantalum

*DischargesC1ifoutputisshortedtoground

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LM317LTypicalApplications

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AdjustableRegulatorwithCurrentLimiter

HighStability10VRegulator

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Shortcircuitcurrentisapproximately600mV/R3,or60mA(comparedtoLM317LZ’s200mAcurrentlimit).

At25mAoutputonly3/4VofdropoccursinR3andR4.

0V–30VRegulator

RegulatorWith15mAShortCircuit

Current

PowerFollower

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Fulloutputcurrentnotavailableathighinput-outputvoltages

AdjustingMultipleOn-CardRegulatorswithSingleControl*

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*Alloutputswithin±100mV†Minimumload−5mA

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LM317LTypicalApplications

100mACurrentRegulator

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1.2V–12VRegulatorwithMinimum

ProgramCurrent

50mAConstantCurrentBatteryChargerforNickel-Cadmium

Batteries

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*Minimumloadcurrent≈2mA

5VLogicRegulatorwithElectronicShutdown*CurrentLimited6VCharger

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*Minimumoutput≈1.2V

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*Setspeakcurrent,IPEAK=0.6V/R1

**1000µFisrecommendedtofilteroutanyinputtransients.

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LM317LTypicalApplications

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ShortCircuitProtected80VSupply

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BasicHighVoltageRegulator

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Q1,Q2:NSD134orsimilarC1,C2:1µF,200Vmylar***Heatsink

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LM317LTypicalApplications

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PrecisionHighVoltageRegulator

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Q1,Q2:NSD134orsimilarC1,C2:1µF,200Vmylar***Heatsink

**MylarisaregisteredtrademarkofDuPontCo.

TrackingRegulatorRegulatorWithTrimmableOutputVoltage

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TrimProcedure:

—IfVOUTis23.08Vorhigher,cutoutR3(iflower,don’tcutitout).—ThenifVOUTis22.47Vorhigher,cutoutR4(iflower,don’t).—ThenifVOUTis22.16Vorhigher,cutoutR5(iflower,don’t).

Thiswilltrimtheoutputtowellwithin±1%of22.00VDC,withoutanyoftheexpenseoruncertaintyofatrimpot(seeLB-46).Ofcourse,thistechniquecanbeusedatanyoutputvoltagelevel.

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A1=LM301A,LM307,orLF13741only

R1,R2=matchedresistorswithgoodTCtracking

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LM317LTypicalApplications

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PrecisionReferencewithShort-CircuitProofOutput

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*R1–R4fromthin-filmnetwork,Beckman694-3-R2K-Dorsimilar

1.2V-25AdjustableRegulator

FullyProtected(Bulletproof)

LampDriver

LampFlasher

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Fulloutputcurrentnotavailableathighinput-outputvoltages

†Optional—improvestransientresponse

*Neededifdeviceismorethan6inchesfromfiltercapacitors

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Outputrate—4flashespersecondat10%dutycycle

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LM317LPhysicalDimensions

inches(millimeters)unlessotherwisenoted

SO-8MoldedPackageNSPackageNumberM08A

TO-92PlasticPackage(Z)NSPackageNumberZ03A

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LM317LPhysicalDimensions

inches(millimeters)unlessotherwisenoted(Continued)

NOTE:UNLESSOTHERWISESPECIFIED.1.EPOXYCOATING

2.63Sn/37PbEUTECTICBUMP.

3.RECOMMENDNON-SOLDERMASKDEFINEDLANDINGPAD.

4.PIN1ISESTABLISHEDBYLOWERLEFTCORNERWITHRESPECTTOTEXTORIENTATIONPINSARENUMBEREDCOUNTERCLOCKWISE.

5.XXXINDRAWINGNUMBERREPRESENTSPACKAGESIZEVARIATIONWHEREX1ISPACKAGEWIDTH,X2ISPACK-AGELENGTHANDX3ISPACKAGEHEIGHT.

6.REFERENCEJEDECREGISTRATIONMO-211,VARIATIONBC.

6-BumpmicroSMD

NSPackageNumberBPA06HPAX1=0.955X2=1.615X3=0.700

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LM317L3-TerminalAdjustableRegulatorNotes

LIFESUPPORTPOLICY

NATIONAL’SPRODUCTSARENOTAUTHORIZEDFORUSEASCRITICALCOMPONENTSINLIFESUPPORTDEVICESORSYSTEMSWITHOUTTHEEXPRESSWRITTENAPPROVALOFTHEPRESIDENTANDGENERALCOUNSELOFNATIONALSEMICONDUCTORCORPORATION.Asusedherein:1.Lifesupportdevicesorsystemsaredevicesorsystemswhich,(a)areintendedforsurgicalimplantintothebody,or(b)supportorsustainlife,andwhosefailuretoperformwhenproperlyusedinaccordancewithinstructionsforuseprovidedinthelabeling,canbereasonablyexpectedtoresultinasignificantinjurytotheuser.

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2.Acriticalcomponentisanycomponentofalifesupportdeviceorsystemwhosefailuretoperformcanbereasonablyexpectedtocausethefailureofthelifesupportdeviceorsystem,ortoaffectitssafetyoreffectiveness.

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Nationaldoesnotassumeanyresponsibilityforuseofanycircuitrydescribed,nocircuitpatentlicensesareimpliedandNationalreservestherightatanytimewithoutnoticetochangesaidcircuitryandspecifications.