Datasheet

ClockandReset
DigitalAudioInterface(PCM2902B)
SupportedInput/OutputData(PCM2902B)
ChannelStatusInformation(PCM2902B)
CopyrightManagement(PCM2902B)
PCM2900B
PCM2902B
www.ti.com ...........................................................................................................................................................................................SLES229–DECEMBER2008
ThePCM2900B/2902Brequiresa12-MHz(±500ppm)clockfortheUSBandaudiofunctions,whichcanbe
generatedbyabuilt-incrystaloscillatorwitha12-MHzcrystalresonator.The12-MHzcrystalresonatormustbe
connectedtoXTI(pin21)andXTO(pin20)withonehigh(1-MΩ)resistorandtwosmallcapacitors,the
capacitanceofwhichdependsontheloadcapacitanceofthecrystalresonator.Theexternalclockcanbe
suppliedfromXTI(pin21).Iftheexternalclockissupplied,XTO(pin20)mustbeleftopen.Becausethereisno
clock-disablingsignal,itisnotrecommendedtousetheexternalclocksupply.SSPND(pin28)isunabletouse
clockdisabling.
ThePCM2900B/2902Bhasaninternalpower-onresetcircuit,whichtriggersautomaticallywhenV
BUS
(pin3)
exceeds2.5Vtypical(2.7Vto2.2V).Approximately700µsisrequireduntilinternalresetrelease.
ThePCM2902BemploysbothS/PDIFinputandoutput.Isochronous-outdatafromthehostareencodedtothe
S/PDIFoutputandtheDACanalogoutput.InputdataareselectedaseitherS/PDIForADCanaloginput.When
thedevicedetectsanS/PDIFinputandsuccessfullylocksthereceiveddata,theisochronous-intransferdata
sourceisautomaticallyselectedfromS/PDIFitself;otherwise,thedatasourceisselectedtoADCanaloginput.
Thisfeatureisacustomeroption.Itistheresponsibilityoftheusertoimplementthisfeature.
ThefollowingdataformatsareacceptedbytheS/PDIFinputandoutput.Allotherdataformatsareunabletouse
S/PDIF.
•48-kHz16-bitstereo
•44.1-kHz16-bitstereo
•32-kHz16-bitstereo
AnymismatchofthesamplingratebetweentheinputS/PDIFsignalandthehostcommandisnotacceptable.
AnymismatchofthedataformatbetweentheinputS/PDIFsignalandthehostcommandmaycauseunexpected
results,withthefollowingexceptions:
•Recordinginmonauralformatfromstereodatainputatthesamedatarate
•Recordingin8-bitformatfrom16-bitdatainputatthesamedatarate
Acombinationofthesetwoconditionsisnotacceptable.
Forplayback,allpossibledataratesourcesareconvertedto16-bitstereoformatatthesamesourcedatarate.
Thechannelstatusinformationisfixedasconsumerapplication,PCMmode,copyright,anddigital/digital
converter.Allotherbitsarefixedas0'sexceptforthesamplefrequency,whichissetautomaticallyaccordingto
thedatareceivedthroughtheUSB.
Isochronous-indataareaffectedbytheserialcopymanagementsystem(SCMS).Whenreceivingdigitalaudio
datathatareindicatedasoriginaldatainthecontrolbit,inputdigitalaudiodatatransfertothehost.Ifthedata
areindicatedasfirstgenerationorhigher,thetransferreddataareroutedtotheanaloginput.
DigitalaudiodataoutputisalwaysencodedasoriginalwithSCMScontrol.
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ProductFolderLink(s):PCM2900BPCM2902B
Not Recommended For New Designs