3.2.3.1BKND_ERRandVALID
3.2.4Speaker/HeadphoneSelector(HP_SEL)
3.2.5Mute(MUTE)
TAS5518C
8-ChannelDigitalAudioPWMProcessor
www.ti.com
SLES238A–SEPTEMBER2008–REVISEDJULY2009
Table3-4.DeviceOutputsDuringBack-EndError
SIGNALSIGNALSTATE
ValidLow
PWMP-outputsM-state=low
PWMM-outputsM-state=low
PWM_HPP-outputsM-state=low
PWM_HPM-outputsM-state=low
SDASignalinput(notdriven)
ThenumberofchannelsthatareaffectedbytheBKND_ERRsignaldependsonthesettingofbitD1of
I
2
Cregister0xE0.IftheI
2
Csettingis0(8-channelmode),theTAS5518CplacesalleightPWMoutputsin
thePWMback-enderrorstate.IftheI
2
Csettingis1,theTAS5518Cisin6-channelmode.Forproper
operationin6-channelmode,thelineoutconfigurationregisters(0x09and0x0A)mustbe0x00insteadof
thedefaultof0xE0.Inthiscase,VALIDispulledLOW,andtheTAS5518CbringsPWMoutputs1,2,3,4,
7,and8toaback-enderrorstate,whilenotaffectinglineoutchannels5and6.Table3-4showsthe
deviceoutputsignalstatesduringback-enderror.
TheHP_SELterminalenablestheheadphoneoutputorthespeakeroutputs.Theheadphoneoutput
receivestheprocesseddataoutputfromDAPandPWMchannels1and2.
In6-channelconfiguration,thisfeaturedoesnotaffectthetwolineoutchannels.
Whenlow,theheadphoneoutputisenabled.Inthismode,thespeakeroutputsaredisabled.Whenhigh,
thespeakeroutputsareenabledandtheheadphoneisdisabled.
Changesinthepinlogiclevelresultinastatechangesequenceusingsoftmutetothehard-mutestate
(M-state)forbothspeakerandheadphonefollowedbyasoftunmute.
WhenHP_SELislow,theconfigurationofchannels1and2isdefinedbytheheadphoneconfiguration
register.WhenHP_SELishigh,thechannel-1and-2configurationregistersdefinetheconfigurationof
channels1and2.
Ifusingtheremapped-outputmixerconfiguration(0xD0bit30=0)inthe6-channelmode,theheadphone
operationismodified.Thatis,followingtheassertionorde-assertionofheadphone,mutemustbe
assertedandde-assertedusingtheMUTEpin.
Themutecontrolprovidesanoiselessvolumeramptosilence.Releasingmuteprovidesanoiselessramp
topreviousvolume.TheTAS5518Chasbothmasterandindividualchannelmutecommands.Aterminal
isalsoprovidedforthemastermute.Theactive-lowmastermuteI
2
CregisterandtheMUTEterminalare
logicallyORedtogether.Ifeitherissettolow,amuteonallchannelsisperformed.Themastermute
commandoperatesonallchannelsregardlessofwhetherthesystemisinthe6-or8-channel
configuration.
Whenmuteisinvoked,thePWMoutputstopsswitchingandthengoestoanidlestate.
ThemastermuteterminalisusedtosupportavarietyofotheroperationsintheTAS5518C,suchas
settingthethebiquadcoefficients,theserialinterfaceformat,andtheclockrates.Amutecommandbythe
mastermuteterminal,individualI
2
Cmute,theAMinterferencemutesequence,thebank-switchmute
sequence,orautomuteoverridesanunmutecommandoravolumecommand.Whileamuteisactive,the
commandedchannelsareplacedinamutestate.Whenachannelisunmuted,itgoestothelast
commandedvolumesettingthathasbeenreceivedforthatchannel.
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