User's Guide SNVA350B–September2008–RevisedApril2013 AN-1858 LM26484 Power Management Unit Evaluation Board 1 Introduction TheLM26484evaluationboardisaworkingdemonstrationoftwostep-downDC-DCconvertersandan LDOcontroller.Thisuser'sguidehelpsyoumakethebestuseoftheLM26484withyourapplication.For morespecificinformationabouthowtheLM26484deviceworksasitrelatestoitselectrical characteristics,pleaserefertoLM26484PowerManagementUnit(SNVS573). Theevaluationboard(Figure1)comeswiththeregulatorspre-configuredtohaveVOUTBuck1setto 1.8V,VOUTBuck2setto1.0V,andVOUTLDOsetto1.0V. BecausetheLM26484isexternallyconfigurableandhasmanyvoltageoptions,itispossibletochange thefeedbacknetworktogetadifferentregulatoroutputvoltage.Detailsareincludedinthisdocument. Comm DC Comm DC Input voltage Input voltage AVDD VIN1 C9 C1 AVIN L1 VOUT1 SW1 ENSW1 C3 R1 C2 ENSW2 FB1 C4 R2 ENLDO PGND_SW1 nPOR LM26484 PVIN C4 and C8 are usually not needed LDOGATE Comm DC LDO_OUT Input voltage VIN2 C10 C5 R5 C11 LDOFB L2 VOUT2 SW2 R6 C6 R3 C7 FB2 C8 R4 D P N A G D A PGND_SW2 Figure1. LM26480EvaluationBoard Alltrademarksarethepropertyoftheirrespectiveowners. SNVA350B–September2008–RevisedApril2013 AN-1858LM26484PowerManagementUnitEvaluationBoard 1 SubmitDocumentationFeedback Copyright©2008–2013,TexasInstrumentsIncorporated

GeneralDescription www.ti.com 2 General Description TheLM26484isamulti-function,configurablePowerManagementUnit.Thisdeviceintegratestwohighly efficient2.0Astep-downDC/DCconverters,oneLDOController,aPOR(PowerOnReset)circuit,and thermaloverloadprotectioncircuitry.Allregulatoroutputvoltagesareexternallyadjustable.TheLDO controllerisalowvoltageNMOSvoltageregulator.TheLM26484isofferedina5× 4× 0.8mm24-pin WQFNpackage(seeFigure2). 19 18 17 16 15 14 13 20 12 21 11 DATE CODE * 22 10 26484SQ 23 9 24 8 1 2 3 4 5 6 7 Figure2.PackageDrawingofLM26484 Table1.PinDescriptions Pin# Name I/O Type(1) Description 1 VIN1 I PWR PowerinDCsourceBuck1PMOS 2 ENSW1 I D EnableforBuck1switcher,alogicHIGHenablesBuck1 3 FB1 I A Buck1feedbackterminal 4 AVIN I PWR Analogpowerforinternalcircuits 5 FB2 I A Buck2feedbackterminal 6 ENSW2 I D EnableforBuck2switcher,alogicHIGHenablesBuck2 7 VIN2 I PWR PowerinDCsourceBuck2PMOS 8 VIN2 I PWR PowerinDCsourceBuck2PMOS 9 SW2 O A Buck2switcheroutput 10 SW2 O A Buck2switcheroutput 11 PGND_SW2 G G Buck2NMOSPowerGround 12 PGND_SW2 G G Buck2NMOSPowerGround 13 ENLDO I D EnableforLDO,alogicHIGHenablesLDO 14 LDOGATE O A LDOControlleroutputtoNMOSpowertransistorGate 15 LDOFB I A LDOControllerinputtofeedbackterminal 16 AGND G G AnalogGND 17 GND G G Ground 18 nPOR O D nPORActivelowResetoutput.nPORremainsLOWwhiletheinputsupplyis belowthreshold,andgoesHIGHafterthethresholdisreachedandtimeddelay 19 AVDD I PWR AnalogPowerPin 20 PGND_SW1 G G Buck1NMOSPowerGround 21 PGND_SW1 G G Buck1NMOSPowerGround 22 SW1 O A Buck1switcheroutput 23 SW1 O A Buck1switcheroutput 24 VIN1 I PWR PowerinDCsourceBuck1PMOS (1) A:AnalogPin,D:DigitalPin,G:GroundPin,PWR:PowerPin 2 AN-1858LM26484PowerManagementUnitEvaluationBoard SNVA350B–September2008–RevisedApril2013 SubmitDocumentationFeedback Copyright©2008–2013,TexasInstrumentsIncorporated

www.ti.com EvaluationBoardDescription Table1.PinDescriptions(continued) Pin# Name I/O Type(1) Description DAP DAP GND GND Connectionisn'tnecessaryforelectricalperformance,butitisrecommended forbetterthermaldissipation. 3 Evaluation Board Description Fromacommoninputvoltage,theuserhasaccesstotwoDC-DCstep-downconvertersandoneLDO controller.Theoutputvoltagesofthetwoconvertersareconfiguredviathefeedbacknetworkwhichis externaltotheLM26484.FromTable2,selectthefeedbacknetworkcomponentsthatcorrelatetothe desiredoutputvoltageandsoldertotheboard. Itisveryimportanttocleantheboardafterassemblyofthefeedbacknetwork.TheFBpinisahigh impedancenode,andanyleakagecausedbythefluxremainingontheboardcouldcauseerrorsinthe outputvoltage. Table2. Buck1/2ConfigurationandComponentSelectionGuide Target IdealRes(KisΩto)rValues Commo(KnΩR)Values wAictthuCaloVmO/URT ADcetlutaalfrVoOmUT FeedbackCapacitors V (V) R1/R3 R2/R4 R1/R3 R2/R4 (V) Target(V) C3/C6(pF) C4/C8(pF) OUT 0.8 120 200 121 200 0.803 0.002 15 none 0.9 160 200 162 200 0.905 0.005 15 none 1 200 200 200 200 1 0 15 none 1.1 240 200 240 200 1.1 0 15 none 1.2 280 200 280 200 1.2 0 12 none 1.3 320 200 324 200 1.31 0.01 12 none 1.4 360 200 357 200 1.393 -0.008 10 none 1.5 400 200 402 200 1.505 0.005 10 none 1.6 440 200 442 200 1.605 0.005 8.2 none 1.7 427 178 432 178 1.713 0.013 8.2 none 1.8 463 178 464 178 1.803 0.003 8.2 none 1.9 498 178 499 178 1.902 0.002 8.2 none 2 450 150 453 150 2.01 0.01 8.2 none 2.1 480 150 475 150 2.083 -0.017 8.2 none 2.2 422 124 422 124 2.202 0.002 8.2 none 2.3 446 124 442 124 2.282 -0.018 8.2 none 2.4 471 124 475 124 2.415 0.015 8.2 none 2.5 400 100 402 100 2.51 0.01 8.2 none 2.6 420 100 422 100 2.61 0.01 8.2 none 2.7 440 100 442 100 2.71 0.01 8.2 33 2.8 460 100 464 100 2.82 0.02 8.2 33 2.9 480 100 475 100 2.875 -0.025 8.2 33 3 500 100 499 100 2.995 -0.005 6.8 33 3.1 520 100 523 100 3.115 0.015 6.8 33 3.2 540 100 536 100 3.18 -0.02 6.8 33 3.3 560 100 562 100 3.31 0.01 6.8 33 3.4 580 100 576 100 3.38 -0.02 6.8 33 3.5 600 100 604 100 3.52 0.02 6.8 33 SNVA350B–September2008–RevisedApril2013 AN-1858LM26484PowerManagementUnitEvaluationBoard 3 SubmitDocumentationFeedback Copyright©2008–2013,TexasInstrumentsIncorporated

LDOController www.ti.com 4 LDO Controller TheLDOcontrollermusthaveitsfeedbacknetworkassembledbeforeproperoperationaswell.Selectthe componentsfromTable3thatcorrespondtothedesiredoutputvoltage.Makesuretocleantheboard aftersolderingthefeedbacknetworkforreasonspreviouslydescribed. Table3. LDOConfigurationandComponentSelectionGuide Feedback Target IdealResistorValues CommonRValues ActualVOUTwith Capacitor ComR(V) V (V) R5(KΩ) R6(KΩ) R5(KΩ) R6(KΩ) C11(pF) OUT 0.8 120 200 120 200 0.8 15 0.9 160 200 162 200 0.905 15 1 200 200 200 200 1 15 1.1 240 200 240 200 1.1 15 1.2 280 200 280 200 1.2 12 1.3 320 200 324 200 1.31 12 1.4 360 200 357 200 1.393 10 1.5 400 200 402 200 1.505 10 5 Jumper Settings Inorderfortheboardtofunctionproperlytherearecertainjumpersthatmustbeinplace,seeTable4. Table4. JumperDescriptions JP1 Mustbeinplace ConnectsVin1toboardpower JP2 Mustbeinplace ConnectsVin2toboardpower JP3 Mustbeinplace ConnectsAVDDtoboardpower JP4 Mustbeinplace ConnectsAVINtoboardpower JP5 Mustbeinplace ThisalternatesbetweenGNDandboardpowertoenableBuck2 JP6 Mustbeinplace ThisalternatesbetweenGNDandboardpowertoenableBuck1 JP7 Mustbeinplace ThisalternatesbetweenGNDandboardpowertoenabletheLDO JP9 Mustbeinplace ConnectsGNDtoboardGND JP10 Optional ChangestheoutputvoltageofBuck2 JP11 Optional ChangestheoutputvoltageoftheLDO JP12 Optional ChangestheoutputvoltageofBuck1 JP14 Mustbeinplace AlternatestheFETDrainvoltagebetweenBuck2andboardpower 4 AN-1858LM26484PowerManagementUnitEvaluationBoard SNVA350B–September2008–RevisedApril2013 SubmitDocumentationFeedback Copyright©2008–2013,TexasInstrumentsIncorporated

www.ti.com UsingEvaluationBoardtoSupplyPower 6 Using Evaluation Board to Supply Power ItisimportanttoconnecttheLM26484BuckandLDOusingpropergroundreturns.Thiswillenablethe outputvoltagetobeascleanaspossible.AsseeninFigure3,connecteachV anditscorresponding OUT groundtotheinputandgroundontheapplicationboard.EachLM26484Buckoutputhasaground associatedwithit,anditsgroundneedstobeconnectedforpropergroundcurrentflow. Figure3.GroundConnections 7 Bill of Materials Table5.BillofMaterials Item Designator Vendor PartNumber Qty. Comp.Type Value 1 Texas LM26484 1 LM26484EvalBoardPCB, Instruments RevA 2 U1 Texas WQFN 1 Instruments 3 C1,C1A,C2,C5, TaiyoYuden JMK316B7226ML-T 8 CAPCER22µF6.3VX7R 22µF C5A,C7,C12,C17 1206 4 C9,C10,C11,C14 Murata GRM21BR71A106KE51L 4 CAPCER10µF10VX7R 10µF 0805 5 C3 Murata ERB21B5C2E8R2CDX1L 1 CAPCER8.2F250V0805 8.2pF 6 C6,C15 Murata ERB21B5C2E150JDX1L 2 CAPCER15F250V0805 15pF 7 C4,C8 NOLOAD NOLOAD 5 NOLOAD 8 C16 Murata GRM32ER61A476KE20L 1 CAPCER47µF10VX5R 47µF 1210 9 L2,L3 Coilcraft LPS4414-501MLB 2 LPS4414SeriesLow 0.5µH ProfileShieldedPower Inductors 10 Q1 Vishay SI1450DH 1 MOSFETN-CH20V1.6A 20V,1.6A SOT-363 11 R2 Panasonic ERJ-3EKF1783V 1 RES178kΩ1/10W1% 178K 0603SMD 12 R1 Panasonic ERJ-3EKF4643V 1 RES464kΩ1/10W1% 464K 0603SMD SNVA350B–September2008–RevisedApril2013 AN-1858LM26484PowerManagementUnitEvaluationBoard 5 SubmitDocumentationFeedback Copyright©2008–2013,TexasInstrumentsIncorporated

LM26484BoardLayout www.ti.com Table5.BillofMaterials(continued) Item Designator Vendor PartNumber Qty. Comp.Type Value 13 R3,R4,R5,R6 Panasonic ERJ-3EKF2003V 4 RES200kΩ1/10W1% 200K 0603SMD 14 R11,R13,R15 NOLOAD NOLOAD 9 NOLOAD 15 R7 Panasonic ERJ-3EKF1003V 1 RES100kΩ1/10W1% 100K 0603SMD 16 JP1,JP2,JP3,JP4, Tyco/AMP 9-146285-0-02 5 2-pinheader100milpitch JP9 17 JP10,JP11,JP12 NOLOAD NOLOAD 3 NOLOAD 18 JP5,JP6,JP7,JP14 Tyco/AMP 9-146285-0-03 4 3-pinheader100milpitch 19 AVIN, Keystone 1573-2 21 silverplatedturret70mil BUCK1_SENSE, drill BUCK2_SENSE, ENLDO,ENSW1, ENSW2,GND, GND1,GND2,GND3, GND_SW1, GND_SW2, LDOGATE,NPOR, VBUCK1,VBUCK2, VDD_M,VDD_M1, VIN1,VIN2,VLDO 20 JP1_SH,JP2_SH, Tyco/AMP 881545-2 9 JumperShunt,0.100"30 JP3_SH,JP4_SH, uinAU(withhandle) JP5_SH,JP6_SH, JP7_SH,JP9_SH, JP14_SH 8 LM26484 Board Layout Figure4.SilkscreenTop 6 AN-1858LM26484PowerManagementUnitEvaluationBoard SNVA350B–September2008–RevisedApril2013 SubmitDocumentationFeedback Copyright©2008–2013,TexasInstrumentsIncorporated

www.ti.com LM26484BoardLayout Figure5.SignalTopLayer Figure6.SignalPlaneGround SNVA350B–September2008–RevisedApril2013 AN-1858LM26484PowerManagementUnitEvaluationBoard 7 SubmitDocumentationFeedback Copyright©2008–2013,TexasInstrumentsIncorporated

LM26484BoardLayout www.ti.com Figure7.SignalPlanVDD_M(BoardPower) Figure8.Signal4Bottom 8 AN-1858LM26484PowerManagementUnitEvaluationBoard SNVA350B–September2008–RevisedApril2013 SubmitDocumentationFeedback Copyright©2008–2013,TexasInstrumentsIncorporated

www.ti.com LM26484BoardSchematic 9 LM26484 Board Schematic C6 VDD_M VDD_M C3 + C16 R3 R1 VBUCK2 VBUCK1 JP10 C8 R4 GND R2 C4 JP12 R13 AVIN R11 ENSW2 ENSW1 GND JP4 VDD_M GND VDD_M C16 VDD_M VDD_M JP2 VIN2 JP5 2 JP6 VIN2 JP1 VDD_M GND C5 C5A C1A C1 GND GND VIN2 ENSW2 FB2 AVIN FB1 ENSW1 VIN1 PIN 7 PIN 6 PIN 5 PIN 4 PIN 3 PIN 2 PIN 1 VIN2 VIN1 GND PIN 8 PIN 24 GND BUCK2_SENSE VBUCK2 L2 0.5 µH VBUCK1 BUCK1_SENSE VBUCK2 SW2 SW1 VBUCK1 0.5µH PIN 9 PIN 23 L3 C17 C7 C2 C12 GND_SW2 SPWIN2 10 LM26484 PINSW 221 GND_SW1 GND PGND_SW2 PGND_SW1 GND PIN 11 PIN 21 GND PGND_SW2 PGND_SW1 GND PIN 12 PIN 20 VDD_M ENLDO LDOGATE LDOFB AGND GND_PIN NPOR AVDD PIN 13 PIN 14 PIN 15 PIN 16 PIN 17 PIN 18 PIN 19 JP3 VDD_M JP7 ENLDO C14 GND VDD_M JP14 VDD_M VDD_M1 R7 100k NPOR VBUCK2 C9 LDOGATE GND JP9 JP11 R15 C10 C15 VLDO GND R5 R6 GND GND Figure9.LM26484BoardSchematic SNVA350B–September2008–RevisedApril2013 AN-1858LM26484PowerManagementUnitEvaluationBoard 9 SubmitDocumentationFeedback Copyright©2008–2013,TexasInstrumentsIncorporated

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