STAC9721 Datasheet, PDF (27/48 Pages) List of Unclassifed Manufacturers – Stereo AC 97 Codec With Multi-Codec Option

SigmaTel, Inc.
Data Sheet
STAC9721
4.4.12 Analog Current Adjust (Index 70h and 72h)
The Analog Current Adjust register (index 72h) is a locked register and can only be
properly written and read from when ABBAh has been written into register 70h. The
BIASx bits allow the analog current to be adjusted with minimal reduction in
performance. The –50% analog current setting is not recommended when a 5V analog
supply is used. The –50% setting for 3.3V supplies is recommended to reduce power
consumption for notebook computers to its lowest level.
Table 18: Analog Current Adjust
BIAS1 BIAS0
0
0
0
1
1
0
1
1
Analog Current
Normal Current
-50% Analog
Current
-25% Analog
Current
+25% Analog
Current
4.4.13 Multi-Channel Programming Register (Index 74h)
This read/write register is used to program the various options for multi-channel
configurations. Only the two LSBs are used (MC0 and MC1), and they define which
AC-Link slot data is supplied to the two PCM output channels on the STAC9721/23.
The purpose of using slot 10 and 11 in the final configuration is to allow for the
possibility of an eight-channel architecture using several STAC9721/23 or STAC9708
devices in the multi-codec configuration. Also see “Multiple Codec Support” discussion
for information on the use of external pins CID1 and CID0.
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