Datasheet

BANKSWITCHING
TAS5706A
TAS5706B
SLOS606D–MARCH2009–REVISEDSEPTEMBER2009............................................................................................................................................. www.ti.com
TheTAS5706Ausesanapproachcalledbankswitchingtogetherwithautomaticsample-ratedetection.All
processingfeaturesthatmustbechangedfordifferentsampleratesarestoredinternallyintheTAS5706A.The
TAS5706Ahasthreefullbanksstoringinformation,onefor32kHz,onefor44.1/48kHz,andoneforallother
datarates.Combinedwiththeclock-rateautodetectionfeature,bankswitchingallowstheTAS5706Atodetect
automaticallyachangeintheinputsamplerateandswitchtotheappropriatebankwithoutanyMCU
intervention.
TheTAS5706Asupportsthreebanksofcoefficientstobeupdatedduringtheinitialization.Onebankisfor32
kHz,asecondbankisfor44.1/48kHz,andathirdbankisforallothersamplerates.Anexternalcontroller
updatesthethreebanks(seetheI
2
Cregistermappingtableforbankablelocations)duringtheinitialization
sequence.
Iftheautobankswitchisenabled(register0x50,bits2:0),thentheTAS5706Aautomaticallyswapsthe
coefficientsforsubsequentsampleratechanges,avoidingtheneedforanyexternalcontrollerinterventionfora
sampleratechange.
Bydefault,bits2:0havethevalue000;thatmeansthebankswitchisdisabled.Inthatstate,anyupdateto
locations0x29–0x3FgointotheDAP.Awritetoregister0x50withbits2:0being001,010,or011bringsthe
systemintothecoefficient-bank-updatestateupdatebank1,updatebank2,orupdatebank3,respectively.Any
subsequentwritetolocations0x29-0x3FupdatesthecoefficientbanksstoredoutsidetheDAP.Afterupdatingall
thethreebanks,thesystemcontrollershouldissueawritetoregister0x50withbits2:0being100;thischanges
thesystemstatetoautomaticbankupdate.Inautomaticbankupdate,theTAS5706Aautomaticallyswapsbanks
basedonthesamplerate.
Intheheadphonemode,speakerequalizationandDRCaredisabled,andtheyarerestoreduponreturningtothe
speakermode.
Commandsequencesforinitializationcanbesummarizedasfollows:
1.Enablefactorytrimforinternaloscillator:Writetoregister0x1Bwithavalue0x00.
2.Updatecoefficients:CoefficientscanbeloadedintoDAPRAMusingthemanualbankmode.
OR
Useautomaticbankmode.
a.Enablebank-1mode:Writetoregister0x50with0x01.Loadthe32-kHzcoefficients.TIALE
cangeneratecoefficients.
b.Enablebank-2mode:Writetoregister0x50with0x02.Loadthe48-kHzcoefficients.
c.Enablebank-3mode:Writetoregister0x50with0x03.Loadtheothercoefficients.
d.Enableautomaticbankswitchingbywritingtoregister0x50with0x04.
3.Bringthesystemoutofall-channelshutdown:Write0tobit6ofregister0x05.
4.Issuemastervolume:Writetoregister0x07withthevolumevalue(0db=0x30).
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TAS5706A is Not Recommended for New Designs