User's Guide SLVU428–June2011 TPS7A3401EVM-042 Evaluation Module This user’s guide describes operational use of the TPS7A3401EVM-042 evaluation module (EVM) as a reference design for engineering demonstration and evaluation of the TPS7A3401, negative voltage, low dropout linear regulator (LDO). Included in this user’s guide are setup instructions, a schematic diagram, layoutandthermalguidelines,andbillofmaterials. Contents 1 Introduction .................................................................................................................. 2 2 Setup ......................................................................................................................... 2 2.1 Input/OutputConnectorsandJumperDescriptions ........................................................... 2 2.2 SolderingGuidelines............................................................................................... 2 2.3 EquipmentInterconnect ........................................................................................... 2 3 Operation..................................................................................................................... 2 4 TestResults ................................................................................................................. 3 5 ThermalGuidelinesandLayoutRecommendations ................................................................... 3 6 BoardLayout ................................................................................................................ 4 7 SchematicandBillofMaterials ........................................................................................... 6 ListofFigures 1 TopAssemblyLayer........................................................................................................ 4 2 TopLayerRouting.......................................................................................................... 4 3 BottomLayerRouting...................................................................................................... 5 4 BottomAssemblyLayer.................................................................................................... 5 5 TPS7A3401EVM-042Schematic......................................................................................... 6 ListofTables 1 ThermalResistance,θ ,andMaximumPowerDissipation........................................................... 3 JA 2 TPS7A4001EVM-709BillofMaterials ................................................................................... 6 PowerPADisatrademarkofTexasInstruments. SLVU428–June2011 TPS7A3401EVM-042EvaluationModule 1 SubmitDocumentationFeedback Copyright©2011,TexasInstrumentsIncorporated

Introduction www.ti.com 1 Introduction TheTexasInstrumentsTPS7A3401EVM-042evaluationmodulehelpsdesignengineerstoevaluatethe operationandperformanceoftheTPS7A3401negativevoltagelinearregulatorforuseintheirowncircuit application.ThisparticularEVMconfigurationcontainsasinglelinearregulatorwithinternalthermaland current-limitshutdowns,andenable(disable)circuitryina3-mmx5-mm,MSOP-8,thermallyenhanced PowerPAD™package.Theregulator,includingexternalcomponents,iscapableofdeliveringupto–200 mAtotheload,dependingontheinput-outputpowerdissipation,atanoperatinginputvoltagedownto –20V.TheEVMoutputvoltageisadjustablebyanexternalresistordividerfrom –1.2Vto–17V.The resistordividerispresettoprovideVOUTapproximatelyequalto–15V. 2 Setup ThissectiondescribesthejumpersandconnectorsontheEVMaswellashowtoproperlyconnect,set up,andusetheTPS7A3401EVM. 2.1 Input/Output Connectors and Jumper Descriptions JP1–EN Outputenable.Toenabletheoutput,connectajumpertoshortON(pin1)toEN (centerpin2).Todisabletheoutput,connectajumpertoshortEN(pin2)toOFF(pin 3). J1– VIN Negativeinputpowersupplyvoltageconnector.Twistthenegativeleadandpositive returnleadfromtheinputpowersupplyandkeepthemasshortaspossibleto minimizeleadinductanceandEMItransmission.Ifthesupplyleadsaregreaterthan6 inches,addadditionalbulkcapacitancebetweenJ2andJ4.Forexample,anadditional 47-µFleadedelectrolyticcapacitorconnectedfromJ1togroundcanimprovethe transientresponseoftheTPS7A3401whileeliminatingunwantedringingontheinput duetolongwireconnections. J2– GND Ground-returnconnectorfortheinputpowersupply(positivesideconnection). J3– GND Outputground-returnconnector. J4– VOUT Regulatedoutputvoltageconnector. 2.2 Soldering Guidelines Anysolderre-worktomodifytheEVMforthepurposeofrepairorotherapplicationreasonsmustbe performedusingahot-airsystemtoavoiddamagingtheintegratedcircuit(IC)especially. 2.3 Equipment Interconnect • Turnofftheinputpowersupplyafterverifyingthatitsoutputvoltageissettoapproximately–18V(–20 Vmaximumnegative)andthecurrentlimitissettoapproximately600mA.Connectthenegative voltageleadfrominputpowersupplytoVIN,attheJ1connectoroftheEVM.Connectthepositive-side returnleadfromtheinputpowersupplytoGNDattheJ2connectoroftheEVM. • Connecta0-mAto200-mAload(I )betweenVOUTattheJ4connectorandtheGNDattheJ3 Load connector. • DisabletheoutputbyconnectingajumperatJ1toshorttheEN(pin2)totheOFF(pin3). 3 Operation • Turnontheinputpowersupply.Verifythattheoutputvoltageisnear0V. • EnabletheoutputbyreconnectingthejumperonJ1toshorttheEN(pin2)totheON(pin1). • VarytheloadcurrentandVINvoltageasnecessaryfortestpurposes Notethatthepowerdissipation(P )acrosstheTPS7A3401iscalculatedtobe disp P =(VIN– VOUT)×I ).BeawarethatforsomeapplicationswheretheVINtoVOUTdifferenceis disp Load large,themaximumjunctiontemperatureforthepartmaybeexceededandthatthermalshutdowncycling mayoccur. 2 TPS7A3401EVM-042EvaluationModule SLVU428–June2011 SubmitDocumentationFeedback Copyright©2011,TexasInstrumentsIncorporated

www.ti.com TestResults 4 Test Results SeetheTypicalCharacteristicssectionoftheTPS7A3401datasheet(SBVS163)tofindcharacteristic performance. 5 Thermal Guidelines and Layout Recommendations Thermalmanagementisakeycomponentofdesignofanypowerconverterandisespeciallyimportant whenthepowerdissipationintheLDOishigh.Usethefollowingformulatoapproximatethemaximum powerdissipationfortheparticularambienttemperature: T =T +P ×θ J A d JA Where: T isthejunctiontemperature. J T istheambienttemperature. A P isthepowerdissipationinthedevice(watts). d θ isthethermalresistancefromjunctiontoambient. JA AlltemperaturesareindegreesCelsius.Themaximum,continuous,operatingjunctiontemperature, T,mustnotbeallowedtoexceed125°C.Thelayoutdesignmustusecoppertraceandplaneareas J effectively,asthermalsinks,inordernottoallowT toexceedthemaximumratingunderall J temperatureandvoltageconditionsforagivenapplication. Thelayoutmustconsidercarefullythethermaldesignoftheprinted-circuitboard(PCB)foroptimal performanceovertemperature.TheMSOP-8(DGN)packageemploysametalPowerPAD™ICtobe solderedtothePCBinorderforthePCBtoactasasinktodissipateheatfromtheLDO.Thisthermal sinkconnection,undertheLDO,istypicallyconnectedtothetoplayergroundcopper,asillustratedinthe Figure2layerroutingfortheEVM.ItisalsoagoodpracticetouseplatedviasplacedinthePowerPAD™ footprintofthePCBtofurthersinkheattothebottomsidecoppergroundplane.Figure4showsthatthis EVMhasnine,10-milviastoservethispurpose.ThePCBforthisTPS7A3401EVM-042EVMisa two-layerboardwith2-oz.copperontopandbottomlayers.TheDGNpackagedrawingcanbefoundat theTexasInstrumentsWebsiteintheproductfolderfortheTPS7A3401LDO. Table1repeatsinformationfromtheDissipationRatingsTableoftheTPS7A3401datasheet(SBVS163) forcomparisonwiththethermalresistance,θ ,calculatedforthisEVMlayouttoshowthevariationin JA thermalresistancesforgivencopperareas.TheHigh-KvalueisdeterminedusingastandardJEDEC high-k(2s2p)boardhavingdimensionsof3-inchx3-inchwith1-ounceinternalpowerandgroundplanes and2-ouncecoppertracesontopandbottomoftheboard. Table1.ThermalResistance,θ ,andMaximumPowerDissipation JA MaximumDissipation MaximumDissipation Board Package θ WithoutDerating WithoutDerating JA (T =25°C) (T =70°C) A A High-K DGN 55.1°C/W 1.83W 1.08W TPS7A3401EVM-042 DGN 49.0°C/W 2.04W 1.12W SLVU428–June2011 TPS7A3401EVM-042EvaluationModule 3 SubmitDocumentationFeedback Copyright©2011,TexasInstrumentsIncorporated

BoardLayout www.ti.com ThethermalresistancefortheTPS7A3401EVM-042,θ ,isthemeasuredvalueforthisparticularlayout JA scheme.Themaximumpowerdissipationisproportionaltothecoppervolumeconnectedtothepackage. 6 Board Layout Figure1.TopAssemblyLayer Figure2.TopLayerRouting 4 TPS7A3401EVM-042EvaluationModule SLVU428–June2011 SubmitDocumentationFeedback Copyright©2011,TexasInstrumentsIncorporated

www.ti.com BoardLayout Figure3.BottomLayerRouting Figure4.BottomAssemblyLayer SLVU428–June2011 TPS7A3401EVM-042EvaluationModule 5 SubmitDocumentationFeedback Copyright©2011,TexasInstrumentsIncorporated

SchematicandBillofMaterials www.ti.com 7 Schematic and Bill of Materials Figure5.TPS7A3401EVM-042Schematic Table2.TPS7A4001EVM-709BillofMaterials Count RefDes Value Description Size PartNumber MFR 1 C1 4.7µF Capacitor,Ceramic,25V,X7R,20% 1206 STD STD 1 C3 0.01µF Capacitor,Ceramic,25V,X5R,20% 0603 STD STD 1 C4 10µF Capacitor,Ceramic,25V,X5R,20% 1210 STD STD 4 J1-2,J4-5 PEC02SAAN Header,Male2-pin,100milspacing 0.100inchx2 PEC02SAAN Sullins 1 JP1 PEC03SAAN Header,Male3-pin,100milspacing 0.100inchx3 PEC03SAAN Sullins 1 R1 24.9K Resistor,Chip,1/16W,1% 0603 STD STD 1 R2 2.1K Resistor,Chip,1/16W,1% 0603 STD STD 1 U1 TPS7A3401DGN IC,–20V,–200mA,Low-NoiseVoltageRegulator HTSSOP TPS7A3401DGN TI 1 Shunt,Black 100-mil 929950-00 3M 1 – PWR042 1.3x2.8inch2layer,PCB PWR042 Any 6 TPS7A3401EVM-042EvaluationModule SLVU428–June2011 SubmitDocumentationFeedback Copyright©2011,TexasInstrumentsIncorporated

EvaluationBoard/KitImportantNotice TexasInstruments(TI)providestheenclosedproduct(s)underthefollowingconditions: Thisevaluationboard/kitisintendedforuseforENGINEERINGDEVELOPMENT,DEMONSTRATION,OREVALUATION PURPOSESONLYandisnotconsideredbyTItobeafinishedend-productfitforgeneralconsumeruse.Personshandlingthe product(s)musthaveelectronicstrainingandobservegoodengineeringpracticestandards.Assuch,thegoodsbeingprovidedare notintendedtobecompleteintermsofrequireddesign-,marketing-,and/ormanufacturing-relatedprotectiveconsiderations, includingproductsafetyandenvironmentalmeasurestypicallyfoundinendproductsthatincorporatesuchsemiconductor componentsorcircuitboards.Thisevaluationboard/kitdoesnotfallwithinthescopeoftheEuropeanUniondirectivesregarding electromagneticcompatibility,restrictedsubstances(RoHS),recycling(WEEE),FCC,CEorUL,andthereforemaynotmeetthe technicalrequirementsofthesedirectivesorotherrelateddirectives. Shouldthisevaluationboard/kitnotmeetthespecificationsindicatedintheUser’sGuide,theboard/kitmaybereturnedwithin30 daysfromthedateofdeliveryforafullrefund.THEFOREGOINGWARRANTYISTHEEXCLUSIVEWARRANTYMADEBY SELLERTOBUYERANDISINLIEUOFALLOTHERWARRANTIES,EXPRESSED,IMPLIED,ORSTATUTORY,INCLUDING ANYWARRANTYOFMERCHANTABILITYORFITNESSFORANYPARTICULARPURPOSE. Theuserassumesallresponsibilityandliabilityforproperandsafehandlingofthegoods.Further,theuserindemnifiesTIfromall claimsarisingfromthehandlingoruseofthegoods.Duetotheopenconstructionoftheproduct,itistheuser’sresponsibilityto takeanyandallappropriateprecautionswithregardtoelectrostaticdischarge. EXCEPTTOTHEEXTENTOFTHEINDEMNITYSETFORTHABOVE,NEITHERPARTYSHALLBELIABLETOTHEOTHER FORANYINDIRECT,SPECIAL,INCIDENTAL,ORCONSEQUENTIALDAMAGES. TIcurrentlydealswithavarietyofcustomersforproducts,andthereforeourarrangementwiththeuserisnotexclusive. TIassumesnoliabilityforapplicationsassistance,customerproductdesign,softwareperformance,orinfringementof patentsorservicesdescribedherein. PleasereadtheUser’sGuideand,specifically,theWarningsandRestrictionsnoticeintheUser’sGuidepriortohandlingthe product.Thisnoticecontainsimportantsafetyinformationabouttemperaturesandvoltages.ForadditionalinformationonTI’s environmentaland/orsafetyprograms,pleasecontacttheTIapplicationengineerorvisitwww.ti.com/esh. NolicenseisgrantedunderanypatentrightorotherintellectualpropertyrightofTIcoveringorrelatingtoanymachine,process,or combinationinwhichsuchTIproductsorservicesmightbeorareused. FCCWarning Thisevaluationboard/kitisintendedforuseforENGINEERINGDEVELOPMENT,DEMONSTRATION,OREVALUATION PURPOSESONLYandisnotconsideredbyTItobeafinishedend-productfitforgeneralconsumeruse.Itgenerates,uses,and canradiateradiofrequencyenergyandhasnotbeentestedforcompliancewiththelimitsofcomputingdevicespursuanttopart15 ofFCCrules,whicharedesignedtoprovidereasonableprotectionagainstradiofrequencyinterference.Operationofthis equipmentinotherenvironmentsmaycauseinterferencewithradiocommunications,inwhichcasetheuserathisownexpense willberequiredtotakewhatevermeasuresmayberequiredtocorrectthisinterference. EVMWarningsandRestrictions ItisimportanttooperatethisEVMwithintheinputvoltagerangeof-22Vto0.3Vandtheoutputvoltagerangeof-20Vto-3V. Exceedingthespecifiedinputrangemaycauseunexpectedoperationand/orirreversibledamagetotheEVM.Ifthereare questionsconcerningtheinputrange,pleasecontactaTIfieldrepresentativepriortoconnectingtheinputpower. Applyingloadsoutsideofthespecifiedoutputrangemayresultinunintendedoperationand/orpossiblepermanentdamagetothe EVM.PleaseconsulttheEVMUser'sGuidepriortoconnectinganyloadtotheEVMoutput.Ifthereisuncertaintyastotheload specification,pleasecontactaTIfieldrepresentative. Duringnormaloperation,somecircuitcomponentsmayhavecasetemperaturesgreaterthan125°C.TheEVMisdesignedto operateproperlywithcertaincomponentsabove125°Caslongastheinputandoutputrangesaremaintained.Thesecomponents includebutarenotlimitedtolinearregulators,switchingtransistors,passtransistors,andcurrentsenseresistors.Thesetypesof devicescanbeidentifiedusingtheEVMschematiclocatedintheEVMUser'sGuide.Whenplacingmeasurementprobesnear thesedevicesduringoperation,pleasebeawarethatthesedevicesmaybeverywarmtothetouch. MailingAddress:TexasInstruments,PostOfficeBox655303,Dallas,Texas75265 Copyright©2011,TexasInstrumentsIncorporated

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