kevin.lan：
这个IC的设计难点在PCB，可能大多数的人都没去仔细看DATASHEET,另外因为布线复杂，建议用4层板。仔细看下下面的指导。如果需要技术支持，凌特的FAE愿意为您效劳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