LM2717MTX-ADJ/NOPB

Texas Instruments

LM2717-ADJ Dual Step-Down DC/DC Converter

Manufacturer: Texas Instruments

Document: 24 Pages / 1Mb

Request Quote Download Datasheet Read online HTML view

More from Texas Instruments Browse L parts

Online Datasheet

Read LM2717MTX-ADJ/NOPB online.

LM2717-ADJ Dual Step-Down DC/DC Converter (Rev. C)

Document overview

Manufacturer or author: Texas Instruments, Incorporated [SNVS407,C]
PDF pages: 24

Technical content

www.ti.com SNVS407C –DECEMBER 2005–REVISED MARCH 2013 LM2717-ADJDualStep-DownDC/DCConverter Check forSamples: LM2717-ADJ 1FEATURES DESCRIPTION The LM2717-ADJ iscomposed of two PWM DC/DC 2• AdjustableBuck Converterwitha 2.2A,0.16Ω, InternalSwitch (Buck 2) internalswitchesformaximum efficiency.Operating frequency can be adjusted anywhere between• OperatingInputVoltageRange of4V to20V 300kHz and 600kHz allowingthe use of small• InputUndervoltageProtection externalcomponents.Externalsoft-startpinsforeach• 300kHz to600kHz Pin AdjustableOperating converterenables the user to tailorthe soft-start Frequency timesto a specificapplication.Each convertermay also be shut down independentlywith its own• Over Temperature Protection shutdown pin.The LM2717-ADJ isavailableina low• Small 24-Lead TSSOP Package profile24-leadTSSOP package ensuringa lowprofile overallsolution.APPLICATIONS

TFT-LCD Displays
Handheld Devices
PortableApplications
Laptop Computers
Automotive Applications Pleasebe aware thatan importantnoticeconcerningavailability,standardwarranty,and use incriticalapplicationsof Texas Instrumentssemiconductorproductsand disclaimerstheretoappearsattheend ofthisdatasheet. 2Alltrademarksarethepropertyoftheirrespectiveowners. PRODUCTION DATA informationiscurrentas ofpublicationdate. Copyright© 2005–2013,Texas InstrumentsIncorporatedProductsconform to specificationsper the terms of the Texas Instrumentsstandardwarranty.Productionprocessingdoes not necessarilyincludetestingofallparameters.

SNVS407C –DECEMBER 2005–REVISED MARCH 2013 www.ti.com TypicalApplicationCircuit Connection Diagram Figure1. 24-Lead TSSOP Top View

2 SubmitDocumentationFeedback Copyright© 2005–2013,Texas InstrumentsIncorporated

ProductFolderLinks:LM2717-ADJ

www.ti.com SNVS407C –DECEMBER 2005–REVISED MARCH 2013 PIN DESCRIPTIONS Pin Name Function 1 PGND Power ground.PGND and AGND pinsmust be connectedtogetherdirectlyatthepart. 2 PGND Power ground.PGND and AGND pinsmust be connectedtogetherdirectlyatthepart. 3 AGND Analogground.PGND and AGND pinsmust be connectedtogetherdirectlyatthepart. 4 FB1 Buck 1 outputvoltagefeedbackinput. 5 VC1 Buck 1 compensationnetworkconnection.Connectedtotheoutputofthevoltageerroramplifier. 6 VBG Bandgap connection. 7 VC2 Buck 2 compensationnetworkconnection.Connectedtotheoutputofthevoltageerroramplifier. 8 FB2 Buck 2 outputvoltagefeedbackinput. 9 AGND Analogground.PGND and AGND pinsmust be connectedtogetherdirectlyatthepart. 10 AGND Analogground.PGND and AGND pinsmust be connectedtogetherdirectlyatthepart. 11 PGND Power ground.PGND and AGND pinsmust be connectedtogetherdirectlyatthepart. 12 PGND Power ground.PGND and AGND pinsmust be connectedtogetherdirectlyatthepart. 13 SW2 Buck 2 power switchinput.Switchconnectedbetween VIN pinsand SW2 pin. 14 VIN Analogpower input.AllVIN pinsareinternallyconnectedand shouldbe connectedtogetherdirectly atthepart. 15 VIN Analogpower input.AllVIN pinsareinternallyconnectedand shouldbe connectedtogetherdirectly atthepart. 16 CB2 Buck 2 converterbootstrapcapacitorconnection. 17 SHDN2 Shutdown pinforBuck 2 converter.Activelow. 18 SS2 Buck 2 softstartpin. 19 FSLCT Switchingfrequencyselectinput.Use a resistortosetthefrequencyanywhere between 300kHz and 600kHz. 20 SS1 Buck 1 softstartpin. 21 SHDN1 Shutdown pinforBuck 1 converter.Activelow. 22 CB1 Buck 1 converterbootstrapcapacitorconnection. 23 VIN Analogpower input.AllVIN pinsareinternallyconnectedand shouldbe connectedtogetherdirectly atthepart. 24 SW1 Buck 1 power switchinput.Switchconnectedbetween VIN pinsand SW1 pin. Copyright© 2005–2013,Texas InstrumentsIncorporated SubmitDocumentationFeedback 3 ProductFolderLinks:LM2717-ADJ

93% Duty Cycle LimitOSC FSLCT DC LIMIT SET PWM Comp RESET OVP Comp Buck Driver BUCK DRIVE Error Amp BG FB1 Bandgap Soft Start Thermal Shutdown VBG VC1 OVP TSH SHDN1 SD Buck Load Current Measurement Buck 1 Converter CB1 SS1 SW1 VIN PGND 93% Duty Cycle LimitOSC FSLCT DC LIMIT SET PWM Comp RESET OVP Comp Buck Driver BUCK DRIVE Error Amp BG FB2 Bandgap Soft Start Thermal Shutdown VBG VC2 OVP TSH SHDN2 SD Buck Load Current Measurement Buck 2 Converter CB2 SS2 SW2 VIN PGND LM2717-ADJ SNVS407C –DECEMBER 2005–REVISED MARCH 2013 www.ti.com Block Diagram

4 SubmitDocumentationFeedback Copyright© 2005–2013,Texas InstrumentsIncorporated

ProductFolderLinks:LM2717-ADJ

www.ti.com SNVS407C –DECEMBER 2005–REVISED MARCH 2013 These deviceshave limitedbuilt-inESD protection.The leadsshouldbe shortedtogetherorthedeviceplacedinconductivefoam duringstorageorhandlingtopreventelectrostaticdamage totheMOS gates. AbsoluteMaximum Ratings (1) VIN −0.3Vto22V SW1 Voltage −0.3Vto22V SW2 Voltage −0.3Vto22V FB1, FB2 Voltages −0.3Vto7V CB1, CB2 Voltages −0.3VtoVIN+7V (VIN=VSW ) VC1 Voltage 1.75V≤ VC1 ≤ 2.25V VC2 Voltage 0.965V≤ VC2 ≤ 1.565V SHDN1 Voltage −0.3Vto7.5V SHDN2 Voltage −0.3Vto7.5V SS1 Voltage −0.3Vto2.1V SS2 Voltage −0.3Vto2.1V FSLCT Voltage AGND to5V Maximum JunctionTemperature 150°C Power Dissipation(2) InternallyLimited Lead Temperature 300°C Vapor Phase (60sec.) 215°C Infrared(15sec.) 220°C ESD Susceptibility(3) Human Body Model 2kV (1) Absolutemaximum ratingsarelimitsbeyond whichdamage tothedevicemay occur.OperatingRatingsareconditionsforwhichthe deviceisintendedtobe functional,butdeviceparameterspecificationsmay notbe ensured.Forensuredspecificationsand test conditions,see theElectricalCharacteristicstable. (2) The maximum allowablepower dissipationisa functionofthemaximum junctiontemperature,TJ(MAX),thejunction-to-ambientthermal resistance,θJA,and theambienttemperature,TA.See theElectricalCharacteristicstableforthethermalresistance.The maximum allowablepower dissipationatany ambienttemperatureiscalculatedusing:PD (MAX) = (TJ(MAX) − TA)/θJA.Exceedingthemaximum allowablepower dissipationwillcause excessivedietemperature,and theregulatorwillgo intothermalshutdown. (3) The human body model isa 100 pF capacitordischargedthrougha 1.5kΩ resistorintoeach pin. OperatingConditions OperatingJunctionTemperatureRange (1) −40°C to+125°C StorageTemperature −65°C to+150°C SupplyVoltage 4V to20V SW1 Voltage 20V SW2 Voltage 20V SwitchingFrequency 300kHz to600kHz (1) Alllimitsspecifiedatroom temperature(standardtypeface)and attemperatureextremes(boldtypeface).Allroom temperaturelimitsare 100% testedorspecifiedthroughstatisticalanalysis.Alllimitsattemperatureextremesarespecifiedviacorrelationusingstandard StatisticalQualityControl(SQC) methods.Alllimitsareused tocalculateAverageOutgoingQualityLevel(AOQL). Copyright© 2005–2013,Texas InstrumentsIncorporated SubmitDocumentationFeedback 5 ProductFolderLinks:LM2717-ADJ

SNVS407C –DECEMBER 2005–REVISED MARCH 2013 www.ti.com ElectricalCharacteristics SpecificationsinstandardtypefaceareforTJ = 25°C and thosewithboldfacetypeapplyoverthefullOperating Temperature Range (TJ = −40°C to+125°C).VIN = 5V,IL = 0A,and FSW = 300kHz unlessotherwisespecified. Min Typ MaxSymbol Parameter Conditions Units(1) (2) (1) IQ TotalQuiescentCurrent(both Not Switching 2.7 6 mA switchers) Switching,switchopen 6 12 mA VSHDN = 0V 9 27 µA %V BG /ΔVIN Bandgap VoltageLine 0.01-0.01 %/VRegulation 0.125 ICL1 (3) Buck 1 SwitchCurrentLimit VIN = 8V (4) 2.2 A VIN = 12V,VOUT = 3.3V 1.4 1.65 2.0 ICL2 (3) Buck 2 SwitchCurrentLimit VIN = 8V (4) 3.2 A VIN = 12V,VOUT = 5V 2.6 3.05 3.5 IB1 Buck 1 FB PinBiasCurrent VIN = 20V 70 400 nA(5) IB2 Buck 2 FB PinBiasCurrent VIN = 20V 65 400 nA(5) VIN InputVoltageRange 4 20 V gm1 Buck 1 ErrorAmp ΔI= 20µA 1340 µmhoTransconductance gm2 Buck 2 ErrorAmp ΔI= 20µA 1360 µmhoTransconductance AV1 Buck 1 ErrorAmp Voltage 134 V/VGain AV2 Buck 2 ErrorAmp Voltage 136 V/VGain D MAX Maximum DutyCycle 89 93 % FSW SwitchingFrequency R F = 46.4k 240 300 360 kHz R F = 22.6k 480 600 720 kHz ISHDN1 Buck 1 Shutdown PinCurrent 0V < VSHDN1 < 7.5V −5 5 µA ISHDN2 Buck 2 Shutdown PinCurrent 0V < VSHDN2 < 7.5V −5 5 µA IL1 Buck 1 SwitchLeakage VIN = 20V 0.01 5 µACurrent IL2 Buck 2 SwitchLeakage VIN = 20V 0.01 5 µACurrent R DSON1 Buck 1 SwitchR DSON (6) ISW = 100mA 180160 m Ω300 R DSON2 Buck 2 SwitchR DSON (6) ISW = 100mA 180160 m Ω300 ThSHDN1 Buck 1 SHDN Threshold OutputHigh 1.8 1.36 V OutputLow 1.33 0.7 (1) Alllimitsspecifiedatroom temperature(standardtypeface)and attemperatureextremes(boldtypeface).Allroom temperaturelimitsare 100% testedorspecifiedthroughstatisticalanalysis.Alllimitsattemperatureextremesarespecifiedviacorrelationusingstandard StatisticalQualityControl(SQC) methods.Alllimitsareused tocalculateAverageOutgoingQualityLevel(AOQL). (2) Typicalnumbers areat25°C and representthemost likelynorm. (3) Dutycycleaffectscurrentlimitdue toramp generator. (4) Currentlimitat0% dutycycle.See TYPICAL PERFORMANCE sectionforSwitchCurrentLimitvs.InputVoltage. (5) BiascurrentflowsintoFB pin. (6) Includesthebond wiresand package leads,R DSON fromVIN pin(s)toSW pin.

6 SubmitDocumentationFeedback Copyright© 2005–2013,Texas InstrumentsIncorporated

ProductFolderLinks:LM2717-ADJ

www.ti.com SNVS407C –DECEMBER 2005–REVISED MARCH 2013 ElectricalCharacteristics(continued) SpecificationsinstandardtypefaceareforTJ = 25°C and thosewithboldfacetypeapplyoverthefullOperating Temperature Range (TJ = −40°C to+125°C).VIN = 5V,IL = 0A,and FSW = 300kHz unlessotherwisespecified. Min Typ MaxSymbol Parameter Conditions Units(1) (2) (1) ThSHDN2 Buck 2 SHDN Threshold OutputHigh 1.8 1.36 V OutputLow 1.33 0.7 ISS1 Buck 1 SoftStartPinCurrent 4 9 15 µA ISS2 Buck 2 SoftStartPinCurrent 4 9 15 µA UVP On Threshold 4 3.8 V OffThreshold 3.6 3.3 θJA ThermalResistance TSSOP, package only 115 °C/W(7) (7) Refertothewww.ti.com/packagingformore detailedthermalinformationand mountingtechniquesfortheTSSOP package. Copyright© 2005–2013,Texas InstrumentsIncorporated SubmitDocumentationFeedback 7 ProductFolderLinks:LM2717-ADJ

INPUT VOLTAGE (V) 100 110 120 130 140 150 160 170 180 190 200 SWITCH RDS(ON) (m: LOAD CURRENT (A) 100 V IN = 5V V IN = 12V V IN = 18V EFFICIENCY (%) 4 6 8 10 12 14 16 18 20 INPUT VOLTAGE (V) 100 110 120 130 140 150 160 170 180 190 200 SWITCH RDS(ON) (m: 4 6 8 10 12 14 16 18 20 INPUT VOLTAGE (V) 290 295 300 305 310 315 320 R F = 46.4k SWITCHING FREQUENCY (kHz) 4 6 8 10 12 14 16 18 20 INPUT VOLTAGE (V) QUIESCENT CURRENT (mA) 4 6 8 10 12 14 16 18 20 INPUT VOLTAGE (V) QUIESCENT CURRENT (PA) LM2717-ADJ SNVS407C –DECEMBER 2005–REVISED MARCH 2013 www.ti.com TypicalPerformance Characteristics Shutdown IQ vs.InputVoltage SwitchingIQ vs.InputVoltage(FSW = 300kHz) Figure2. Figure3. SwitchingFrequency vs.InputVoltage(FSW = 300kHz) Buck 1 R DS(ON) vs.InputVoltage Figure4. Figure5. Buck 2 R DS(ON) vs.InputVoltage Buck 1 Efficiencyvs.Load Current(VOUT = 3.3V) Figure6. Figure7.

8 SubmitDocumentationFeedback Copyright© 2005–2013,Texas InstrumentsIncorporated

ProductFolderLinks:LM2717-ADJ

-40 -20 0 20 40 60 80 AMBIENT TEMPERATURE (oC) 2.8 2.9 3.1 3.2 3.3 3.4 SWITCH CURRENT LIMIT (A) VOUT = 3.3V VOUT = 5V -40 -20 0 20 40 60 80 AMBIENT TEMPERATURE (oC) 1.4 1.45 1.5 1.55 1.6 1.65 1.7 SWITCH CURRENT LIMIT (A) VOUT = 3.3V VOUT = 5V 5 7 9 11 13 15 17 19 INPUT VOLTAGE (V) 1.2 1.4 1.6 1.8 2.2 2.4 SWITCH CURRENT LIMIT (A) VOUT = 3.3V VOUT = 5V 5 9 13 17 INPUT VOLTAGE (V) 2.2 2.4 2.6 2.8 3.2 3.4 3.6 3.8 SWITCH CURRENT LIMIT (A) 7 11 15 19 VOUT = 3.3V VOUT = 5V 0 0.5 1 1.5 2 2.5 LOAD CURRENT (A) 100EFFICIENCY (%) V IN = 18V 0 0.5 1 1.5 2 2.5 LOAD CURRENT (A) 100EFFICIENCY (%) V IN = 18V LM2717-ADJ www.ti.com SNVS407C –DECEMBER 2005–REVISED MARCH 2013 TypicalPerformance Characteristics(continued) Buck 2 Efficiencyvs.Load Current(VOUT = 15V) Buck 2 Efficiencyvs.Load Current(VOUT = 5V) Figure8. Figure9. Buck 1 Switch CurrentLimitvs.InputVoltage Buck 2 Switch CurrentLimitvs.InputVoltage Figure10. Figure11. Buck 1 Switch CurrentLimitvs.Temperature(VIN = 12V) Buck 2 Switch CurrentLimitvs.Temperature(VIN = 12V) Figure12. Figure13. Copyright© 2005–2013,Texas InstrumentsIncorporated SubmitDocumentationFeedback 9 ProductFolderLinks:LM2717-ADJ

RF (k/c87) SWITCHING FREQUENCY (kHz) VIN = 12V -40 -20 0 20 40 60 80 100 120 JUNCTION TEMPERATURE (°C) 100 150 200 250 300 POWER SWITCH R DSON (m/c87) VIN = 8V -40 -20 0 20 40 60 80 100 120 JUNCTION TEMPERATURE (°C) 100 150 200 250 POWER SWITCH R DSON (m/c87) VIN = 8V LM2717-ADJ SNVS407C –DECEMBER 2005–REVISED MARCH 2013 www.ti.com TypicalPerformance Characteristics(continued) Buck 1 Switch ON Resistancevs.Temperature Buck 2 Switch ON Resistancevs.Temperature Figure14. Figure15. SwitchingFrequency vs.R F Resistance Figure16.

10 SubmitDocumentationFeedback Copyright© 2005–2013,Texas InstrumentsIncorporated

ProductFolderLinks:LM2717-ADJ

:R FB1(3) = RFB2(4) x VOUT - VFB1(2) VFB1(2) VOUT VIN , D' = (1-D) D = LM2717-ADJ www.ti.com SNVS407C –DECEMBER 2005–REVISED MARCH 2013 BUCK OPERATION PROTECTION (BOTH REGULATORS) The LM2717-ADJ has dedicatedprotectioncircuitryrunningduringnormal operationto protectthe IC. The ThermalShutdown circuitryturnsoffthepower deviceswhen thedietemperaturereachesexcessivelevels.The UVP comparatorprotectsthepower devicesduringsupplypower startupand shutdown topreventoperationat voltageslessthantheminimum inputvoltage.The OVP comparatorisused topreventtheoutputvoltagefrom risingat no loads allowingfullPWM operationover allload conditions.The LM2717-ADJ also featuresa shutdown mode foreach converterdecreasingthe supplycurrentto approximately10µA (bothin shutdown mode). CONTINUOUS CONDUCTION MODE The LM2717-ADJ containscurrent-mode,PWM buck regulators.A buck regulatorstepstheinputvoltagedown to a loweroutputvoltage.In continuousconductionmode (when the inductorcurrentnever reaches zero at steadystate),thebuck regulatoroperatesintwo cycles.The power switchisconnectedbetween VIN and SW1 and SW2. Inthefirstcycleofoperationthetransistorisclosedand thediodeisreversebiased.Energy iscollectedinthe inductorand theloadcurrentissuppliedby C OUT and therisingcurrentthroughtheinductor. Duringthesecond cyclethetransistorisopen and thediodeisforwardbiaseddue tothefactthattheinductor currentcannotinstantaneouslychange direction.The energystoredintheinductoristransferredtotheloadand outputcapacitor. The ratioofthesetwo cyclesdeterminestheoutputvoltage.The outputvoltageisdefinedapproximatelyas: where

where D isthedutycycleoftheswitch
D and D ′ willbe requiredfordesigncalculation (1) The LM2717-ADJ has a minimum switchON timewhichcorrespondstoa minimum dutycycleofapproximately 10% at 600kHz operationand approximately5% at 300kHz operation.In the case of some high voltage differentialapplications(low duty cycleoperation)thisminimum duty cyclemay be exceeded causingthe feedbackpinover-voltageprotectiontotripas theoutputvoltagerises.Thiswillputthedeviceintoa PFM type operationwhich can cause an unpredictablefrequencyspectrumand may cause theaverageoutputvoltageto riseslightly.Ifthisisa concerntheswitchingfrequencymay be loweredand/ora pre-loadadded totheoutputto keep thedevicefullPWM operation.Note thattheOVP functionmonitorstheFB pinso itwillnotfunctionifthe feedbackresistorisdisconnectedfrom the output.Due to slightdifferencesbetween the two convertersitis recommended thatBuck 1 be used forthelowerofthetwo outputvoltagesforbestoperation. DESIGN PROCEDURE Thissectionpresentsguidelinesforselectingexternalcomponents. SETTING THE OUTPUT VOLTAGE The outputvoltageissetusingthe feedbackpinand a resistordividerconnectedto the outputas shown in Figure20.The feedbackpinvoltage(VFB )is1.258V,so theratioofthefeedbackresistorssetstheoutputvoltage accordingtothefollowingequation: (2) Copyright© 2005–2013,Texas InstrumentsIncorporated SubmitDocumentationFeedback 11 ProductFolderLinks:LM2717-ADJ

(H)LMIN = (D-0.5+2/S)(VIN-VOUT )RDSON (1-D)(0.164*FSW ) LM2717-ADJ SNVS407C –DECEMBER 2005–REVISED MARCH 2013 www.ti.com INPUT CAPACITOR A low ESR aluminum,tantalum,or ceramiccapacitorisneeded between theinputpinand power ground.This capacitorpreventslargevoltagetransientsfrom appearingattheinput.The capacitorisselectedbased on the RMS currentand voltagerequirements.The RMS currentisgivenby: (3) The RMS currentreachesitsmaximum (IOUT /2)when VIN equals2VOUT .Thisvalueshouldbe calculatedforboth regulatorsand added togivea totalRMS currentrating.Foran aluminum orceramiccapacitor,thevoltagerating shouldbe atleast25% higherthanthemaximum inputvoltage.Ifa tantalumcapacitorisused,thevoltagerating requiredisabouttwicethemaximum inputvoltage.The tantalumcapacitorshouldbe surgecurrenttestedby the manufacturertopreventbeingshortedby theinrushcurrent.The minimum capacitorvalueshouldbe 47µF for loweroutputloadcurrentapplicationsand lessdynamic (quicklychanging)loadconditions.For higheroutput currentapplicationsor dynamic loadconditionsa 68µF to100µF low ESR capacitorisrecommended. Itisalso recommended toputa smallceramiccapacitor(0.1µF to4.7µF) between theinputpinsand ground toreduce highfrequencyspikes. INDUCTOR SELECTION The most criticalparameterfortheinductorina currentmode switcheristheminimum valuerequiredforstable operation.To preventsubharmonicoscillationsand achievegood phase margina targetminimum valueforthe inductoris: (4) Where VIN istheminimum inputvoltageand R DSON isthemaximum switchON resistance.For beststabilitythe inductorshouldbe intherange of0.5LMIN (absoluteminimum) and 2LMIN .Using an inductorwitha valueless than 0.5LMIN can cause subharmonicoscillations.The inductorshouldmeet thisminimum requirementat the peak inductorcurrentexpectedfortheapplicationregardlessofwhat theinductorripplecurrentand outputripple voltagerequirementsare.A valuelargerthan 2LMIN isacceptableifthe ripplerequirementsof the application requireitbutitmay reducethephase marginand increasethedifficultyincompensatingthecircuit. The most importantparametersfortheinductorfroman applicationsstandpointaretheinductance,peak current and theDC resistance.The inductanceisrelatedtothepeak-to-peakinductorripplecurrent,theinputand the outputvoltages(for300kHz operation): (5) A highervalueofripplecurrentreducesinductance,butincreasestheconductanceloss,coreloss,and current stressfortheinductorand switchdevices.Italsorequiresa biggeroutputcapacitorforthesame outputvoltage ripplerequirement.A reasonablevalueissettingtheripplecurrenttobe 30% oftheDC outputcurrent.Sincethe ripplecurrentincreaseswiththe inputvoltage,the maximum inputvoltageisalways used to determinethe inductance.The DC resistanceof the inductorisa key parameterforthe efficiency.Lower DC resistanceis availablewitha biggerwindingarea.A good tradeoffbetween the efficiencyand the core sizeislettingthe inductorcopperlossequal2% oftheoutputpower. OUTPUT CAPACITOR The selectionofC OUT isdrivenby themaximum allowableoutputvoltageripple.The outputrippleintheconstant frequency,PWM mode isapproximatedby: (6) The ESR term usuallyplaysthedominantroleindeterminingthevoltageripple.Low ESR ceramic,aluminum electrolytic,ortantalumcapacitors(suchas MuRata MLCC, TaiyoYuden MLCC, NichiconPL series,Sanyo OS- CON, Sprague 593D, 594D, AVX TPS, and CDE polymeraluminum)isrecommended. An aluminum electrolytic capacitoris not recommended for temperaturesbelow −25°C since itsESR risesdramaticallyat cold temperatures.Ceramic or tantalumcapacitorshave much betterESR specificationsatcoldtemperatureand is preferredforlowtemperatureapplications.

12 SubmitDocumentationFeedback Copyright© 2005–2013,Texas InstrumentsIncorporated

ProductFolderLinks:LM2717-ADJ

www.ti.com SNVS407C –DECEMBER 2005–REVISED MARCH 2013 BOOTSTRAP CAPACITOR A 4.7nFceramiccapacitororlargerisrecommended forthebootstrapcapacitor.Forapplicationswhere theinput voltageislessthan twicethe outputvoltagea largercapacitorisrecommended, generally0.1µF to 1µF to ensureplentyofgatedrivefortheinternalswitchesand a consistentlylowR DSON . SOFT-START CAPACITOR (BOTH REGULATORS) The LM2717-ADJ containscircuitrythatcan be used to limitthe inrushcurrenton start-upof the DC/DC switchingregulators.Thisinrushcurrentlimitingcircuitryservesas a soft-start.The externalSS pinsareused to tailorthe soft-startfora specificapplication.A current(ISS ) chargesthe externalsoft-startcapacitor,C SS . The soft-starttimecan be estimatedas: TSS = C SS *0.6V/ISS (7) When programmingthesoft-starttimeuse theequationgivenintheSoft-StartCapacitorsectionabove.The soft- startfunctionisused simplytolimitinrushcurrenttothedevicethatcouldstresstheinputvoltagesupply.The soft-starttimedescribedabove isthe timeittakesforthe currentlimitto ramp to maximum value.When this functionisused thecurrentlimitstartsata low valueand increasestonominalatthesetsoft-starttime.Under maximum loadconditionstheoutputvoltagemay riseatthesame rateas thesoft-start,however atlightor no loadconditionstheoutputvoltagewillrisemuch fasteras theswitchwillnotneed toconductmuch currentto chargetheoutputcapacitor. SHUTDOWN OPERATION (BOTH REGULATORS) The shutdown pinsoftheLM2717-ADJ are designedso thattheymay be controlledusing1.8V or higherlogic signals.Ifthe shutdown functionisnot to be used the pin may be leftopen. The maximum voltageto the shutdown pinshouldnotexceed 7.5V.Iftheuse ofa highervoltageisdesireddue tosystem orotherconstraints itmay be used, however a 100k or largerresistoris recommended between the appliedvoltageand the shutdownpintoprotectthedevice. SCHOTTKY DIODE The breakdown voltageratingofD 1 and D 2 ispreferredtobe 25% higherthanthemaximum inputvoltage.The currentratingforthe diode should be equal to the maximum outputcurrentforbest reliabilityin most applications.Incases where theinputvoltageismuch greaterthantheoutputvoltagetheaveragediodecurrent islower.Inthiscase itispossibletouse a diodewitha loweraveragecurrentrating,approximately(1-D)*IOUT however thepeak currentratingshouldbe higherthanthemaximum loadcurrent. LOOP COMPENSATION The generalpurpose of loop compensationis to meet staticand dynamic performancerequirementswhile maintainingstability.Loop gainiswhat isusuallychecked todeterminesmall-signalperformance.Loop gainis equaltotheproductofcontrol-outputtransferfunctionand theoutput-controltransferfunction(thecompensation networktransferfunction).The DC loop gain of the LM2717 isusuallyaround 55dB to 60dB when loaded. Generallyspeakingitisa good ideatohave a loopgainslopethatis-20dB /decadefroma verylowfrequencyto wellbeyond the crossoverfrequency.The crossoverfrequencyshouldnot exceed one-fifthof the switching frequency,i.e.60kHz inthecase of300kHz switchingfrequency.The higherthebandwidthis,thefastertheload transientresponsespeed willpotentiallybe.However,ifthedutycyclesaturatesduringa loadtransient,further increasingthe smallsignalbandwidthwillnot help.Since the control-outputtransferfunctionusuallyhas very limitedlow frequencygain,itisa good ideatoplacea poleinthecompensationatzerofrequency,so thatthe low frequencygainwillbe relativelylarge.A largeDC gainmeans highDC regulationaccuracy(i.e.DC voltage changes littlewithloadorlinevariations).The restofthecompensationscheme depends highlyon theshape of thecontrol-outputplot. As shown inFigure17,theexample control-outputtransferfunctionconsistsofone pole(fp),one zero(fz),and a doublepoleatfn(halftheswitchingfrequency).The followingcan be done tocreatea -20dB /decaderoll-offof theloopgain:Placethefirstpoleat0Hz, thefirstzeroatfp,thesecond poleatfz,and thesecond zeroatfn. The resultingoutput-controltransferfunctionisshown inFigure18. Copyright© 2005–2013,Texas InstrumentsIncorporated SubmitDocumentationFeedback 13 ProductFolderLinks:LM2717-ADJ

fp max = 2S 300k 10P 100 PFx xx 0.5 2S 5: 100 PFx x + = 584 Hz fp min = 2S 300k 10P 100 PFx xx 0.5 2S 50: 100 PFx x + = 297 Hz fz = 1 2S 20 m: 100 PFx x = 80 kHz 10 100 1k 10k 100k 1M FREQUENCY (Hz) -60 -40 -20 GAIN (dB) -45 -90 -135 -180 PHASE (°) Asymptotic Gain Phase -20dB/dec (fp1 is at zero frequency) -20dB/dec FREQUENCY GAIN (dB) B fz1 fz2fp2 LM2717-ADJ SNVS407C –DECEMBER 2005–REVISED MARCH 2013 www.ti.com Figure17.Control-OutputTransferFunction Figure18.Output-ControlTransferFunction The control-outputcorner frequencies,and thus the desiredcompensation corner frequencies,can be determinedapproximatelyby thefollowingequations: where

C o istheoutputcapacitance
R e istheoutputcapacitanceESR
fistheswitchingfrequency (8) where
C o istheoutputcapacitance
R o istheloadresistance
fistheswitchingfrequency (9) Sincefpisdeterminedby theoutputnetwork,itwillshiftwithloading(Ro)and dutycycle.Firstdeterminethe rangeoffrequencies(fpmin/max)ofthepoleacrosstheexpectedloadrange,thenplacethefirstcompensation zerowithinthatrange. Example: Vo = 5V, R e = 20m Ω, C o = 100µF, R omax = 5V/100mA = 50Ω, R omin = 5V/1A = 5Ω, L = 10µH, f = 300kHz: (10) (11) (12) Once thefprangeisdetermined,R c1 shouldbe calculatedusing:

14 SubmitDocumentationFeedback Copyright© 2005–2013,Texas InstrumentsIncorporated

ProductFolderLinks:LM2717-ADJ

C c1 = 1 2S 297 Hz 9.76kx x |56 nF R c1 = 20k + 59k 20k |9.76k1350P 3.3 x LM2717-ADJ www.ti.com SNVS407C –DECEMBER 2005–REVISED MARCH 2013 where

B isthedesiredgaininV/V atfp(fz1)
gm isthetransconductanceoftheerroramplifier
1 and R2 arethefeedbackresistorsas shown inFigure19 (13) A gainvaluearound10dB (3.3v/v)isgenerallya good startingpoint. Example:B = 3.3v/v,gm=1350 µmho, R1 = 20 KΩ,R2 = 59 KΩ: (14) BandwidthwillvaryproportionaltothevalueofRc1.Next,Cc1 can be determinedwiththefollowingequation: (15) Example:fpmin= 297 Hz,Rc1 = 20 KΩ: (16) The valueofC c1 shouldbe withintherange determinedby fpmin/max.A highervaluewillgenerallyprovidea more stableloop,buttoohigha valuewillslowthetransientresponsetime. The compensationnetwork(Figure19)willalsointroducea lowfrequencypolewhichwillbe closeto0Hz. A second poleshouldalsobe placedatfz.Thispolecan be createdwitha singlecapacitorCc2 and a shorted Rc2 (seeFigure19).The minimum valueforthiscapacitorcan be calculatedby: (17) Cc2 may notbe necessary,however itdoes createa more stablecontrolloop.Thisisespeciallyimportantwith highloadcurrents. Example:fz= 80 kHz,Rc1 = 20 KΩ: (18) A second zerocan alsobe added witha resistorinserieswithCc2. Ifused,thiszeroshouldbe placedatfn, where thecontroltooutputgainrollsoffat-40dB/dec.Generally,fnwillbe wellbelow the0dB leveland thuswill have littleeffecton stability.Rc2 can be calculatedwiththefollowingequation: (19) Figure19. Compensation Network Copyright© 2005–2013,Texas InstrumentsIncorporated SubmitDocumentationFeedback 15 ProductFolderLinks:LM2717-ADJ

SNVS407C –DECEMBER 2005–REVISED MARCH 2013 www.ti.com Note thatthevaluescalculatedheregivea good baselineforstabilityand willwork wellwithmost applications. The valuesinsome cases may need tobe adjustedsome foroptimum stabilityor thevaluesmay need tobe adjusteddependingon a particularapplicationsbandwidthrequirements. LAYOUT CONSIDERATIONS The LM2717-ADJ uses two separategroundconnections,PGND forthedriversand boostNMOS power device and AGND forthesensitiveanalogcontrolcircuitry.The AGND and PGND pinsshouldbe tieddirectlytogether atthepackage.The feedbackand compensationnetworksshouldbe connecteddirectlytoa dedicatedanalog groundplaneand thisgroundplanemust connecttotheAGND pin.Ifno analoggroundplaneisavailablethen the ground connectionsof the feedback and compensation networks must tiedirectlyto the AGND pin. ConnectingthesenetworkstothePGND can injectnoiseintothesystemand effectperformance. The inputbypass capacitorC IN,as shown inFigure20,must be placedclosetotheIC.Thiswillreducecopper traceresistancewhicheffectsinputvoltagerippleoftheIC.Foradditionalinputvoltagefiltering,a 0.1µF to4.7µF bypass capacitorscan be placedinparallelwithC IN,closetotheVIN pinstoshuntany highfrequencynoiseto ground.The outputcapacitors,C OUT1 and C OUT2 , shouldalsobe placedcloseto the IC.Any copper trace connectionsforthe C OUTX capacitorscan increasethe seriesresistance,which directlyeffectsoutputvoltage ripple.The feedbacknetwork,resistorsR FB1(3)and R FB2(4),shouldbe keptclosetotheFB pin,and away fromthe inductortominimizecoppertraceconnectionsthatcan injectnoiseintothesystem.Traceconnectionsmade to the inductorsand schottkydiodes should be minimizedto reduce power dissipationand increaseoverall efficiency.For more detailon switchingpower supplylayoutconsiderationssee ApplicationNote AN-1149: LayoutGuidelinesforSwitchingPower Supplies(SNVA021 ).

APPLICATION INFORMATION

Table1.Some Recommended Inductors(OthersMay Be Used) Manufacturer Inductor ContactInformation Coilcraft DO3316 and DT3316 series www.coilcraft.com 800-3222645 TDK SLF10145 series www.component.tdk.com 847-803-6100 Pulse P0751 and P0762 series www.pulseeng.com Sumida CDRH8D28 and CDRH8D43 series www.sumida.com Table2.Some Recommended InputAnd Output Capacitors(OthersMay Be Used) Manufacturer Capacitor ContactInformation VishaySprague 293D, 592D, and 595D seriestantalum www.vishay.com TaiyoYuden HighcapacitanceMLCC ceramic www.t-yuden.com ESRD seriecPolymerAluminum ElectrolyticCornellDubilier www.cde.comSPV and AFK seriesV-chipseries MuRata HighcapacitanceMLCC ceramic www.murata.com

ProductFolderLinks:LM2717-ADJ

3.3V OUT1 8V to 20V IN 5V OUT2 PGND RFB3 59k RFB4 20k RF *Connect CINA (pin 23) and CINB (pins 14,15) as close as possible to the VIN pins. 68 /c109F COUT1A 1 /c109F ceramic 22 /c109H MBRS240 CBOOT1 *CINA CIN 68 /c109F CSS1 CC1 CBG CC2 CSS2 AGND RC2 RC1 20k 10k 4.7 nF 1 nF 47 nF 4.7 nF 47 nF VIN VIN CB2 AGND *CINB 4.7 /c109F ceramic 4.7 /c109F ceramic 1 /c109F CBOOT2 COUT2A 1 /c109F ceramic 22.6k RFB1RFB2 33.2k20k 1 /c109F PGND FB1 VC1 VBG SS2 VC2 FB2 AGND AGND PGND PGND PGND SW1 VIN CB1 SHDN1 SS1 FSLCT SHDN2 SW2 LM2717-ADJ 22 /c109H MBRS240 COUT2 68 /c109F COUT1 3.3V OUT1 17V to 20V IN 15V OUT2 PGND RFB3 221k RFB4 20k RF *Connect CINA (pin 23) and CINB (pins 14,15) as close as possible to the VIN pins. 68 /c109F COUT1A 1 /c109F ceramic 22 /c109H MBRS240 4.7 nF CBOOT1 *CINA CIN 68 /c109F CSS1 CC1 CBG CC2 CSS2 AGND RC2 RC1 20k 4.7 nF 1 nF 47 nF 4.7 nF 47 nF VIN VIN CB2 AGND *CINB 4.7 /c109F ceramic 4.7 /c109F ceramic 1 /c109F CBOOT2 COUT2A 1 /c109F ceramic 22.6k RFB1RFB2 33.2k20k LM2717-ADJ www.ti.com SNVS407C –DECEMBER 2005–REVISED MARCH 2013 Figure20. 15V,3.3VOutput Application Figure21. 5V,3.3VOutput Application Copyright© 2005–2013,Texas InstrumentsIncorporated SubmitDocumentationFeedback 17 ProductFolderLinks:LM2717-ADJ

1.8V OUT1 5V to 15V IN 3.3V OUT2 PGND RFB3 33.2k RFB4 20k RF *Connect CINA (pin 23) and CINB (pins 14,15) as close as possible to the VIN pins. 47 /c109F ceramic COUT1A 47 /c109F ceramic 10 /c109H MBRS240 CBOOT1 *CINA CIN 68 /c109F CSS1 CC1 CBG CC2 CSS2 AGND RC2 RC1 82 nF 1 nF 47 nF 82 nF 47 nF VIN VIN CB2 AGND *CINB 4.7 /c109F ceramic 4.7 /c109F ceramic 1 /c109F CBOOT2 COUT2A 47 /c109F ceramic 22.6k RFB1RFB2 8.66k20.5k 1 /c109F LM2717-ADJ SNVS407C –DECEMBER 2005–REVISED MARCH 2013 www.ti.com Figure22. 3.3V,1.8VOutput Application

ProductFolderLinks:LM2717-ADJ

www.ti.com SNVS407C –DECEMBER 2005–REVISED MARCH 2013

REVISION HISTORY

www.ti.com 7-Oct-2013 Addendum-Page 1 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Drawing Pins Package Qty Eco Plan (2) Lead/Ball Finish MSL Peak Temp (3) Op Temp (°C) Device Marking (4/5) Samples LM2717MT-ADJ/NOPB ACTIVE TSSOP PW 24 61 Green (RoHS & no Sb/Br) CU SN Level-1-260C-UNLIM -40 to 125 LM2717 MT-ADJ LM2717MTX-ADJ/NOPB ACTIVE TSSOP PW 24 2500 Green (RoHS & no Sb/Br) CU SN Level-1-260C-UNLIM -40 to 125 LM2717 MT-ADJ (1) The marketing status values are defined as follows: ACTIVE: Product device recommended for new designs. LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect. NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design. PREVIEW: Device has been announced but is not in production. Samples may or may not be available. OBSOLETE: TI has discontinued the production of the device. (2) Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability information and additional product content details. TBD: The Pb-Free/Green conversion plan has not been defined. Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes. Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above. Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight in homogeneous material) (3) MSL, Peak Temp. -- The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature. (4) There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device. (5) Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation of the previous line and the two combined represent the entire Device 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.

*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 PACKAGE MATERIALS INFORMATION www.ti.com 23-Sep-2013 Pack Materials-Page 1

*All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) LM2717MTX-ADJ/NOPB TSSOP PW 24 2500 367.0 367.0 35.0 PACKAGE MATERIALS INFORMATION www.ti.com 23-Sep-2013 Pack Materials-Page 2

Texas InstrumentsIncorporatedand itssubsidiaries(TI)reservetherighttomake corrections,enhancements,improvementsand other changes toitssemiconductorproductsand servicesperJESD46, latestissue,and todiscontinueany productorserviceperJESD48, latest issue.Buyersshouldobtainthelatestrelevantinformationbeforeplacingordersand shouldverifythatsuch informationiscurrentand complete.Allsemiconductorproducts(alsoreferredtohereinas “components”)aresoldsubjecttoTI’s termsand conditionsofsale suppliedatthetimeoforderacknowledgment. TIwarrantsperformanceofitscomponents tothespecificationsapplicableatthetimeofsale,inaccordancewiththewarrantyinTI’s terms and conditionsofsaleofsemiconductorproducts.Testingand otherqualitycontroltechniquesareused totheextentTIdeems necessary tosupportthiswarranty.Exceptwhere mandated by applicablelaw,testingofallparametersofeach component isnotnecessarily performed. TIassumes no liabilityforapplicationsassistanceorthedesignofBuyers’products.Buyersareresponsiblefortheirproductsand applicationsusingTIcomponents.To minimizetherisksassociatedwithBuyers’productsand applications,Buyersshouldprovide adequatedesignand operatingsafeguards. TIdoes notwarrantorrepresentthatany license,eitherexpressorimplied,isgrantedunderany patentright,copyright,mask work right,or otherintellectualpropertyrightrelatingtoany combination,machine,orprocessinwhichTIcomponents orservicesareused.Information publishedby TIregardingthird-partyproductsorservicesdoes notconstitutea licensetouse such productsorservicesora warrantyor endorsementthereof.Use ofsuch informationmay requirea licensefroma thirdpartyunderthepatentsorotherintellectualpropertyofthe thirdparty,ora licensefromTIunderthepatentsorotherintellectualpropertyofTI. ReproductionofsignificantportionsofTIinformationinTIdatabooks ordatasheetsispermissibleonlyifreproductioniswithoutalteration and isaccompaniedby allassociatedwarranties,conditions,limitations,and notices.TIisnotresponsibleorliableforsuch altered documentation.Informationofthirdpartiesmay be subjecttoadditionalrestrictions. ResaleofTIcomponents orserviceswithstatementsdifferentfromorbeyond theparametersstatedby TIforthatcomponent orservice voidsallexpressand any impliedwarrantiesfortheassociatedTIcomponent orserviceand isan unfairand deceptivebusinesspractice. TIisnotresponsibleorliableforany such statements. Buyeracknowledgesand agreesthatitissolelyresponsibleforcompliancewithalllegal,regulatoryand safety-relatedrequirements concerningitsproducts,and any use ofTIcomponents initsapplications,notwithstandingany applications-relatedinformationorsupport thatmay be providedby TI.Buyerrepresentsand agreesthatithas allthenecessaryexpertisetocreateand implementsafeguardswhich anticipatedangerousconsequencesoffailures,monitorfailuresand theirconsequences,lessenthelikelihoodoffailuresthatmightcause harm and takeappropriateremedialactions.BuyerwillfullyindemnifyTIand itsrepresentativesagainstany damages arisingoutoftheuse ofany TIcomponents insafety-criticalapplications. Insome cases,TIcomponents may be promotedspecificallytofacilitatesafety-relatedapplications.Withsuch components,TI’s goalisto helpenablecustomerstodesignand createtheirown end-productsolutionsthatmeet applicablefunctionalsafetystandardsand requirements.Nonetheless,such components aresubjecttotheseterms. No TIcomponents areauthorizedforuse inFDA ClassIII(orsimilarlife-criticalmedicalequipment)unlessauthorizedofficersoftheparties have executeda specialagreementspecificallygoverningsuch use. OnlythoseTIcomponents whichTIhas specificallydesignatedas militarygradeor“enhanced plastic”aredesignedand intendedforuse in military/aerospaceapplicationsorenvironments.Buyeracknowledgesand agreesthatany militaryoraerospaceuse ofTIcomponents whichhave not been so designatedissolelyattheBuyer's risk,and thatBuyerissolelyresponsibleforcompliancewithalllegaland regulatoryrequirementsinconnectionwithsuch use. TIhas specificallydesignatedcertaincomponents as meetingISO/TS16949 requirements,mainlyforautomotiveuse.Inany case ofuse of non-designatedproducts,TIwillnotbe responsibleforany failuretomeet ISO/TS16949. Products Applications Audio www.ti.com/audio Automotiveand Transportationwww.ti.com/automotive Amplifiers amplifier.ti.com Communicationsand Telecom www.ti.com/communications Data Converters dataconverter.ti.com Computers and Peripherals www.ti.com/computers DLP ® Products www.dlp.com Consumer Electronics www.ti.com/consumer-apps DSP dsp.ti.com Energyand Lighting www.ti.com/energy Clocksand Timers www.ti.com/clocks Industrial www.ti.com/industrial Interface interface.ti.com Medical www.ti.com/medical Logic logic.ti.com Security www.ti.com/security Power Mgmt power.ti.com Space,Avionicsand Defense www.ti.com/space-avionics-defense Microcontrollers microcontroller.ti.com Videoand Imaging www.ti.com/video RFID www.ti-rfid.com OMAP ApplicationsProcessors www.ti.com/omap TIE2E Community e2e.ti.com WirelessConnectivity www.ti.com/wirelessconnectivity MailingAddress:Texas Instruments,PostOfficeBox 655303,Dallas,Texas 75265 Copyright© 2013,Texas InstrumentsIncorporated

Product Information