ddx chescc主页个人数字音频功率放大器培训作者peter billy规格书training.pptx

DigitalAudioPowerAmplifierTrainingforDDXCHESCCHomePersonalAudioPreparedby:PeterZHANGTV-AudioCoreTeamMemberDate:Aug-18-05

DDXDigitalDesignDDXEliminatesDACandAnalogSignals

DDXDigitalControlof3-StatePowerStage

DDXDriveStatesDDXDampedStateIncreaseEfficiencyandLowersEMIComparedtoBinaryDesigns

DDX3-StateModulationTernaryModulationproducelesscarrierbandenergythenconventionalClass-DthatuseBinaryModulationTernaryonlyproducesenergytoproduceasignal.WhennosignalpresentloadconnectedtoGND.

DDXEfficiencyAdvantage

LayoutCriticalSMDCapsCriticalbypasscap.SuppressspikesonVccpins,100nFSMDceramicX7Raresuggested.The1uFmustbeSMDtantalumorceramic,don’tuseradialAluminum.

CommonPCBmistakesSTA500505STA500505STA500505STA500505STA500505STA500505Tooclose!MagneticCouplingCausescrosstalkanddistortionGoodspacingkeepsmagneticfluxlinesfromcouplingintoadjacentinductors

Aboardlayoutexample

APCBdesignexample

HowtoAvoidPopNoise

PWMR’sDegradePerformance

HowtocalculatePoutKnowing:Rds_on=PowerPchannel/NchannelMosfetRds_onIsc=ShortcircuitcurrentlimitMi_max=max.modulationindexPout=(Mi_max?Vcc)2xRl2?(Rl+2Rds_on)2Ipeak=Mimax?Vcc2Rl+2?Rds_onWhere:Mimax=0.94,Rds_on=0.2ohm

HowtocalculatePoutSingleEndedKnowing:Rds_on=PowerPchannel/NchannelMosfetRds_onIsc=ShortcircuitcurrentlimitMi_max=max.modulationindexPout=(Mi_max?Vcc)2xRl8?(Rl+Rds_on)2Ipeak=Mimax?Vcc2(Rl+Rds_on)Where:Mimax=0.88,Rds_on=0.2ohm

HowtocalculateBTLfilterChalf=0.707/2π?fc?RhalfLhalf=1.414?Rh/2π?fcCombiningtwohalf-circuitmodelsweobtaintheactualBTLcircuit.Rl=2?RhalfChalf=0.707/2π?fc?RloadLhalf=Lhalf=1.414?Rload/4π?fcCload=DifferentialCapacitor(filmorX7R)MustbeaddedtwoCommonmodecapsabout10%of2ClforHFbypass

Somesuggestedvalues8ohm4ohm22uH1