STAC9708 Datasheet, PDF (7/56 Pages) List of Unclassifed Manufacturers – Multi-Channel AC97 Codec With Multi-Codec Option

SigmaTel, Inc.
Preliminary
STAC9708/11
Figure 2. STAC9708 Block Diagram
Power
Management
AC-link
SYNC
BIT_CLK
SDATA_OUT
SDATA_IN
RESET
Multi-Codec
ID0
ID1
Digital
Interface
Registers
64 x 16 bits
4 stereo
sources
PCM out DACs
48Kss
DAC
DAC
DAC
DAC
PCM in ADCs
ADC
ADC
48Kss
2 mono sources
mono
stereo
M IXER
Analog mixing
and
Gain control
DAC_OUT
LINE_OUT
MONO_OUT
Mic
M
M IC 1
Boost
U
0/20 dB
X
M IC 2
The STAC9708/11 block diagram, above, illustrates its primary functional blocks. It performs fixed 48K sample
rate D-A & A-D conversion, mixing, and analog processing. The digital interface communicates with the AC'97
controller via the five wire AC-Link and contains the 64 word by 16-bit registers. Four, fixed 48Ks/s DAC’s
support two stereo PCM-out channels for surround sound applications requiring four speakers. The digital mix of
all software sources, including the internal synthesizer and any other digital sources, is performed in the digital
controller. The Mixer block mixes the PCM_OUT with any analog sources, then outputs to LINE_OUT. The
surround DACs are output to DAC_OUT, and this stereo output has independent volume control. In addition, the
surround DACs can be input to the Mixer block and output to LINE_OUT. The MONO_OUT delivers either mic
only or a mono mix of sources from the mixer. The two fixed 48Ks/s ADC’s take any mix of mono or stereo
sources and convert it to a stereo PCM-in signal. All ADC's and DAC's operate at 18-bit resolution.
The STAC9708/11 is designed primarily to support multi-channel, 4-speaker PC audio. However, true AC-3
playback can be achieved for 6-speaker applications by taking advantage of the multi-codec option in the
STAC9708/11. Using this option with a STAC9704/07 as the primary codec, and the STAC9708 as the secondary
codec, 6-channel output can be achieved in an AC'97 architecture. Also, the STAC9708/11 provides for a stereo
enhancement feature, Sigmatel Surround 3D or SS3D. SS3D provides the listener with several options to
expand the soundstage beyond the normal 2-speaker arrangement.
Together with the logic component (controller or advanced core logic chip-set) of AC'97, STAC9708/11 can be
SoundBlaster^® and Windows Sound System^® compatible. SoundBlaster^® is a registered trademark of Creative
Labs. Windows^® is a registered trademark of Microsoft Corporation.
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10/02/98