Arcam RDAC - User Manual download pdf (Page 4)

InputStagesandswitchingCircuitpages2and3

TheinputsaresplitintotwogroupswiththeWolfsonSPDIFreceiveratlocationIC201dealing

withOpticalandCoaxialselectionwhilsttheMUXatlocationsIC202AIC202BandIC205A

switchbetweenSPDIF(optorcoax)andUSBorKLEERundercontrolfrommainmicro.

SPDIFinput

TheWolfsonWM8805SPDIFreceiversuppliesdatainaformatofData,LRCLK,BCLKandMLCK,

theoutputofIC201runsdirectlytotheDACviatheMUXatlocationIC202Awithexceptionof

theMCLKthistakeapaththruIC203aspartoftheMCLKMUXbetweenUSB/KLEERandSPDIF

MCLK’s.

USBinput

TheUSBdataarrivesatCON100beforetravelingtotheUSBstreamingcontrolchipatlocation

IC103viatheESDprotectionChipatlocationIC101thechipisloadedwiththeDCS

asynchronous/isochronousinputsystemfromIC100atbootup.

IC103hasitownMCLKsourceatlocationIC204anotherWM8805thistimeusedasanadaptive

clocksourcetheoutputisbufferedbyIC203C

TheData,LRCLK,BCLKareswitchedtotheDACviaIC202BwiththeMCLKcomingviaIC203.

DACandAudioStagescircuitpage4

TheWolfson8741DACcanbefoundatlocationIC301andtakesitssuppliesfrom3V3Dand

5VDAC,dataentersthechiponpins1–5andshouldbeseenasbelow.



AnalogueaudioleavestheDACasbalancedpairsonpins16/17(left)and12/13(right)audio

thentravelsthruandfilternetworkenterstheOp‐ampatlocationIC300a/b(L/R)andthen

ontoIC302a/b(L/R)outputmutingistwofoldwithbothDACmute(transistormute)andfull

mute(relay)theDACmuteisprovidedbytransistorsTR302andTR305switchingtheaudio

downto0vthisunderthecontroloftheDACMUTElinefromIC107,therelaymuteisprovided

byRLY300andtriggeredfrom2linesonebeingthepowerdetectsourcedfromD400atpower

In–underlowpowertherelaywillcloseat5.3vD.CandisflippedbyIC105incombinationwith

IC104theoutputofIC104islowtomutetherelayisswitchedbyTR300.

Pinloc Signaltype

Pin1 LRCK

Pin2 SDATA

Pin3 BCK

Pin5 MCLK

1 2 3 4 5 6 7 8 9 ... 13 14

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Arcam RDAC - User Manual Page 4