kevin.lan：
這個IC的設計難點在PCB，可能大多數(shù)的人都沒去仔細看DATASHEET,另外因為布線復雜，建議用4層板。仔細看下下面的指導。如果需要技術支持，凌特的FAE愿意為您效勞Q47401838UseplanesforVINandVOUTtomaintaingoodvoltagefilteringandtokeeppowerlosseslow.?Floodallunusedareasonalllayerswithcopper.Floodingwithcopperwillreducethetemperatureriseofpowercomponents.ConnectthecopperareastoanyDCnet(VINorGND).Whenlayingouttheprintedcircuitboard,thefollowingchecklistshouldbeusedtoensureproperoperationoftheLTC3789.TheseitemsarealsoillustratedinFigure13.?Segregatethesignalandpowergrounds.AllsmallsignalcomponentsshouldreturntotheSGNDpinatonepoint,whichisthentiedtothePGNDpinclosetotheinductorcurrentsenseresistorRSENSE.?PlaceswitchBandswitchCasclosetothecontrolleraspossible,keepingthePGND,BGandSWtracesshort.?KeepthehighdV/dTSW1,SW2,BOOST1,BOOST2,TG1andTG2nodesawayfromsensitivesmall-signalnodes.?ThepathformedbyswitchA,switchB,D1andtheCINcapacitorshouldhaveshortleadsandPCtracelengths.ThepathformedbyswitchC,switchD,D2andtheCOUTcapacitoralsoshouldhaveshortleadsandPCtracelengths.?Theoutputcapacitor(–)terminalsshouldbeconnectedascloselyaspossibletothe(–)terminalsoftheinputcapacitor.?ConnectthetopdriverboostcapacitorCAcloselytotheBOOST1andSW1pins.ConnectthetopdriverboostcapacitorCBcloselytotheBOOST2andSW2pins.?ConnecttheinputcapacitorsCINandoutputcapacitorsCOUTcloselytothepowerMOSFETs.ThesecapacitorscarrytheMOSFETACcurrentintheboostandbuckregion.?ConnectVFBpinresistivedividerstothe(+)terminalsofCOUTandsignalground.AsmallVFBbypasscapacitormaybeconnectedcloselytotheLTC3789SGNDpin.TheR2connectionshouldnotbealongthehighcurrentornoisepaths,suchastheinputcapacitors.?RouteSENSE–andSENSE+leadstogetherwithminimumPCtracespacing.Avoidhavingsenselinespassthroughnoisyareas,suchasswitchnodes.ThefiltercapacitorbetweenSENSE+andSENSE–shouldbeascloseaspossibletotheIC.EnsureaccuratecurrentsensingwithKelvinconnectionsattheSENSEresistor.OnelayoutexampleisshowninFigure14.?ConnecttheITHpincompensationnetworkcloselytotheIC,betweenITHandthesignalgroundpins.ThecapacitorhelpstofiltertheeffectsofPCBnoiseandoutputvoltageripplevoltagefromthecompensationloop.?ConnecttheINTVCCbypasscapacitor,CVCC,closelytotheIC,betweentheINTVCCandthepowergroundpins.ThiscapacitorcarriestheMOSFETdrivers’currentpeaks.Anadditional1μFceramiccapacitorplacedimmediatelynexttotheINTVCCandPGNDpinscanhelpimprovenoiseperformancesubstantially.APPLICATIONSINFORMATIONGNDVOUT