Datasheet

LoudnessFunction
Volume
Biquad(0x24)
From
Input
Mux
To
Output
Mux
Loudness
Biquad(0x23)
Gain=G
1ifVol 1/G
0ifVol 1/G+1/Scale
1 Scale(Vol 1/G)otherwise
£
³
- -
0ifVol 1/G
1ifVol 1/G+1/Scale
Scale(Vol 1/G)otherwise
£
³
-
B0273-01
Scale=1/(1 1/G)-
TAS5706A
TAS5706B
SLOS606D–MARCH2009–REVISEDSEPTEMBER2009............................................................................................................................................. www.ti.com
TheTAS5706AprovidesadirectformIbiquadforloudnessonthesubwooferchannel.Thefirstbiquadis
containedinagain-compensationcircuitthatmaintainstheoverallsystemgainat1orlesstopreventclippingat
loudvolumesettings.ThisgaincompensationisshowninFigure46
Figure46.BiquadGainControlStructure
Table1.LoudnessTableExampleforGain=4,1/G=0.25,Scale=1.33
Volume0.1250.250.3750.50.6250.750.87511.1251.251.3751.51.6251.751.8752
Biquadpath110.8330.6660.50.3330.166000000000
Directpath000.1660.3330.50.6660.833111111111
Totalgain1111111111111111
Thebiquadsareimplementedinadirectform-Iarchitecture.Thedirectform-Istructureprovidesaseparatedelay
elementandmixer(gaincoefficient)foreachnodeinthebiquadfilter.
Thefive26-bit(3.23)coefficientsforthebiquadareprogrammableviatheI
2
Cinterface.
Thefollowingstepsareinvolvedinusingaloudnessbiquadwiththevolumecompensationfeature:
1.Programthebiquadwithaloudnessfilter.
2.Program0x26(1/G)and0x28(scale).
3.Enablevolumecompensationinregister0x0E.
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TAS5706A is Not Recommended for New Designs