STAC9766 Datasheet, PDF (7/97 Pages) Integrated Device Technology – TWO-CHANNEL, 20-BIT, AC’97 2.3 CODECS WITH STEREO MICROPHONE AND MIC/JACK SENSING

STAC9766/9767
TWO-CHANNEL, 20-BIT, AC’97 2.3 CODECS WITH STEREO MICROPHONE AND MIC/JACK SENSING
PC AUDIO
AC-Link to any digital component of AC'97 providing flexibility in the audio system design. Packaged
in an AC'97 compliant 48-pin TQFP, the STAC9766/9767 can be placed on a motherboard, daughter
boards, PCI, AMR, CNR, MDC or ACR cards.
The STAC9766/9767 block diagram is illustrated in Figure 1. It provides variable sample rate Digi-
tal-to-Analog (DA) and Analog-to-Digital (AD) conversion, mixing, and analog processing. Supported
audio sample rates include 48KHz, 44.1KHz, 32 KHz, 22.05KHz, 16KHz, 11.025KHz, and 8KHz;
additional rates are supported in the STAC9766/9767 soft audio drivers. All ADCs and DACs oper-
ate at 20-bit resolution.
Two 20-bit DACs convert the digital stereo PCM-out content to audio. The MIXER block combines
the PCM_OUT with any analog sources to drive the LINE_OUT and HP_OUT outputs. The
MONO_OUT delivers either microphone only, or a mono mix of sources from the MIXER. The stereo
variable sample rate 20-bit ADCs provide record capability for any mix of mono or stereo sources,
and deliver a digital stereo PCM-in signal back to the AC-Link. The microphone input and mono mix
input can be recorded simultaneously, thus allowing for an all digital output in support of the digital
ready initiative. For a digital ready record path, the microphone is connected to the left channel ADC
while the mono output of the stereo mixer is connected to right channel ADC.
The STAC9766/9767 includes full Stereo Microphone Pre-Amp support and can be used with the
10dB, 20dB and 30dB Microphone Boost options. This integration allows for additional cost savings
and options.
The STAC9766/9767 includes jack sensing on the Headphone and Line_Out. The STAC9766/9767
jack sense can detect the presence of devices on the Headphone and Line Outputs and on both Mic
inputs. With proprietary IDT current- and impedance-sensing techniques, the impedance load on the
Headphone and Line Outputs can also be detected. The GPIOs on the STAC9766/9767 remain
available for advanced configurations.
The STAC9766/9767 implementation of jack sense uses the Extended Paging Registers defined by
the AC'97 2.3 Specification. This allows for additional registry space to hold the identification infor-
mation about the CODEC, the jack sensing details and results, and the external surroundings of the
CODEC. The information within the Extended Paging Registers will allow for the automatic configu-
ration of the audio subsystem without end-user intervention. For example, the BIOS can populate
the Extended Paging Registers with valuable information for both the audio driver and the operating
system such as gain and attenuation stages, input population and input phase. With this input infor-
mation, the IDT driver will automatically provide to the Volume Control Panel only the volume sliders
that are implemented in the system, thus improving the end-user's experience with the PC.
The information in the Extended Paging Registers will also allow for automatic configuration of
microphone inputs, the ability to switch between SPDIF and analog outputs, the routing of the mas-
ter volume slider to the proper physical output, and SoftEQ configurations. The fully parametric IDT
SoftEQ can be initiated upon jack insertion and sensed impedance levels.
The STAC9766/9767 also offers two styles of PC BEEP, Analog and Digital. The digital PC BEEP is
a new feature added to the AC’97 Specification Rev 2.3.
The STAC9766/9767 is designed primarily to support stereo (2-speaker) audio. True AC-3 playback
can be achieved for 6-speaker applications by taking advantage of the multi-CODEC option avail-
able in the STAC9766/9767 to support multiple CODECs in an AC'97 architecture. Additionally, the
IDT™
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TWO-CHANNEL, 20-BIT, AC’97 2.3 CODECS WITH STEREO MICROPHONE AND MIC/JACK SENSING
STAC9766/9767
V 7.4 12/06