STAC9708 Datasheet, PDF (35/56 Pages) List of Unclassifed Manufacturers – Multi-Channel AC97 Codec With Multi-Codec Option

SigmaTel, Inc.
Preliminary
STAC9708/11
Figure 12. Example of STAC9708/11 Powerdown/Powerup flow
PR0=1
PR1=1
PR2=1
PR4=1
Normal
ADCs off
PR0
DACs off
PR1
Analog off Digital I/F off
PR2 or PR3
PR4
PR0=0
&
ADC=1
PR1=0
&
DAC=1
PR2=0
&
ANL=1
Warm Reset
Ready =1
Default
Cold Reset
Shut off
Coda-link
The above figure illustrates one example procedure to do a complete powerdown of STAC9708/11. From normal
operation, sequential writes to the Powerdown Register are performed to power down STAC9708/11 a piece at a
time. After everything has been shut off, a final write (of PR4) can be executed to shut down the AC-Link. The
part will remain in sleep mode with all its registers holding their static values. To wake up, the AC'97 controller
will send an extended pulse on the sync line, issuing a warm reset. This will restart the AC-Link (resetting PR4
to zero). The STAC9708/11 can also be woken up with a cold reset. A cold reset will reset all of the registers to
their default states. When a section is powered back on, the Powerdown Control/Status register (index 26h)
should be read to verify that the section is ready (stable) before attempting any operation that requires it.
Figure 13. STAC9708/11 Powerdown/Powerup flow with analog still alive
PR0=1
PR1=1
PR4=1
Normal
ADCs off
PR0
DACs off
PR1
PR0=0
&
ADC=1
PR1=0
&
DAC=1
Digital I/F
off PR4
Warm Reset
Shut off
Coda-link
The above figure illustrates a state when all the mixers should work with the static volume settings that are
contained in their associated registers. This configuration can be used when playing a CD (or external LINE_IN
source) through STAC9708/11 to the speakers, while most of the system in low power mode. The procedure for
this follows the previous except that the analog mixer is never shut down.
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10/02/98