STAC9250 Datasheet, PDF (16/137 Pages) Integrated Device Technology – TWO-CHANNEL HD AUDIO CODEC WITH MODEM & DUAL DIGITAL MICROPHONE INTERFACES

STAC9250/9251
TWO-CHANNEL HD AUDIO CODEC WITH MODEM & DUAL DIGITAL MICROPHONE INTERFACES
PC AUDIO
3. DETAILED DESCRIPTION
3.1. SPDIF Input
SPDIF IN can operate at 44.1 KHz or 96 KHz, and implements internal Jack Sensing. A sophisti-
cated digital PLL allows automatic rate detection and accurate data recovery. The ability to directly
accept consumer SPDIF voltage levels eliminates the need for costly external receiver ICs.
Advanced features such as record slot select and SPDIF_IN routing to the DAC allows for simulta-
neous record and play.
3.2. SPDIF Output
SPDIF OUT can operate at 44.1 KHz, 48 KHz, 88.2 KHz, and 96 KHz, as defined in the Intel High
Definition Audio Specification, with resolutions up to 24 bits. This insures compatibility with all con-
sumer audio gear and allows for convenient integration into home theater systems and media center
PCs.
3.3. Digital Microphone Support (STAC9251 only)
The STAC9251 has a three-pin digital microphone interface that accepts high-rate, single-bit data
streams from two digital microphones. Each microphone requires only one data line. Both micro-
phones share a single clock line. This robust digital interface gives designers the flexibility to place
the microphones in the optimum location on a system (such as along the top of the screen bezel)
and use a simple, 3-wire ribbon cable to directly connect the microphones to the STAC9251
CODEC.
3.4. SiLabs System Side Modem
A licensed Silicon Labs System Side modem based on the Si3054 architecture is integrated into
STAC9250/9251. Combined with a Silicon Labs Line Side IC (Si3080 or similar), the STAC9250/
9251 allows designers to implement a two-chip HD Audio and HD Modem solution for significant
cost and board space savings.
3.5. Mono Out
The MONO Output is connected to pin 37 and has independent volume and mute control (see the
Widget listing for details). The MONO Output derives it’s input from the output of the summing node
that drives PORT A and PORT D. The following analog signals feed the summing amplifier that
feeds the MONO Out summing amplifier:
• DAC Output: When enabled, both DAC Outputs are summed together.
• Analog PC Beep: Source from Pin 12
• ADC Input: Stereo analog feed into the stereo ADC input.
The combination of the stereo channels from DAC are combined into a single analog signal with a
-6dB degradation in signal strength.
IDT™
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TWO-CHANNEL HD AUDIO CODEC WITH MODEM & DUAL DIGITAL MICROPHONE INTERFACES
STAC9250/9251
V 1.1 102706