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DecouplingCapacitors
supplyvoltagelimitingat4.5v
LayoutRecommendations
ExposedPadOnTPA4411RTJPackageOption
SGNDandPGNDConnections
TPA4411
SLOS430–AUGUST2004
applicationinformation(持续)
TheTPA4411isacaplessheadphoneamplifierthatrequiresadequatepowersupplydecouplingtoensurethat
thenoiseandtotalharmonicdistortion(thd)arelow.agoodlowequivalent-序列-阻抗(等效串联电阻)陶瓷的
电容,typically2.2µf,placedascloseaspossibletothedevicev
DD
leadworksbest.placingthisdecoupling
capacitorclosetothetpa4411isimportantfortheperformanceoftheamplifier.forfilteringlowerfrequency
noisesignals,a10-µforgreatercapacitorplacedneartheaudiopoweramplifierwouldalsohelp,butitisnot
requiredinmostapplicationsbecauseofthehighpsrrofthisdevice.
thetpa4411hasabuilt-inchargepumpwhichservestogenerateanegativerailfortheheadphoneamplifier.
becausetheheadphoneamplifieroperatesfromapositivevoltageandnegativevoltagesupply,circuitryhas
beenimplementedtoprotectthedevicesintheamplifierfromanovervoltagecondition.oncethesupplyisabove
4.5v,thetpa4411canshutdowninanovervoltageprotectionmodetopreventdamagetothedevice.这
tpa4411resumesnormaloperationoncethesupplyisreducedto4.5vorlower.
TheexposedmetalpadontheTPA4411RTJpackagemustbesoldereddowntoapadonthePCBinorderto
maintainreliability.
ThepadonthePCBshouldbeallowedtofloatandnotbeconnectedtogroundorpower
.
Connectingthispadtopowerorgroundpreventsthedevicefromworkingproperlybecauseitisconnected
internallytopvss.
TheSGNDandPGNDpinsoftheTPA4411mustberoutedseparatelybacktothedecouplingcapacitorinorder
toprovideproperdeviceoperation.ifthesgndandpgndpinsareconnecteddirectlytoeachother,thepart
functionswithoutriskoffailure,butthenoiseandthdperformancedonotmeetthespecifications.
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