STAC9721 Datasheet, PDF(5/48 Page) List of Unclassifed Manufacturers – Stereo AC 97 Codec With Multi-Codec Option

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STAC9721 Datasheet, PDF (5/48 Pages) List of Unclassifed Manufacturers – Stereo AC 97 Codec With Multi-Codec Option

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SigmaTel, Inc.

Data Sheet

STAC9721

AC-link

SYNC

BIT_CLK

SDATA_OUT

SDATA_IN

RESET

Power

Management

Digital

Interface

Registers

64 x 16 bits

4 stereo

sources

PCM out DACs

48Kss

DAC

PCM in ADCs

ADC

48Kss

2 mono sources

mono

stereo

MIXER

Analog mixing

and

Gain control

LNLVL_OUT

LINE_OUT

MONO_OUT

Mic

MIC1

Boost

0/20 dB

MIC2

Figure 2. STAC9721/23 Block Diagram

The STAC9721/23 block diagram is illustrated above. 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. Two, fixed 48Ks/s DACâs

support two stereo PCM-out channels. 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 and LNLVL_OUT. The

MONO_OUT delivers either mic only or a mono mix of sources from the mixer. The two fixed 48Ks/s

ADCâs 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 STAC9721/23 is designed primarily to support stereo, 2-speaker audio. However, true AC-3

playback can be achieved for 6-speaker applications by taking advantage of the multi-codec option in the

STAC9721/23. Using this option with a STAC9704/07/21/23 or the 4-channel STAC9708 as the primary

codec, and the STAC9721/23 as the secondary codec, 6-channel output can be achieved in an AC'97

architecture. Also, the STAC9721/23 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, the

STAC9721/23 can be SoundBlasterï and Windows Sound Systemï compatible. SoundBlasterï is a

registered trademark of Creative Labs. Windowsï is a registered trademark of Microsoft Corporation.

04/07/00

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