STAC9766XXTAEC1X IDT, Integrated Device Technology Inc, STAC9766XXTAEC1X Datasheet - Page 44

• Manufacturer Part Number: STAC9766XXTAEC1X
• Manufacturer: IDT, Integrated Device Technology Inc

Specifications of STAC9766XXTAEC1X

• Single Supply Voltage (typ): 3.3/5V
• Single Supply Voltage (min): 3.135/4.75V
• Single Supply Voltage (max): 3.465/5.25V
• Package Type: TQFP
• Lead Free Status / RoHS Status: Compliant

7. SPDIF AND PC BEEP
IDT™
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
7.1.
7.2.
SPDIF Digital Mux
PC Beep Implementation
7.2.1.
7.2.2.
The STAC9766/9767 incorporates a digital output that supports SPDIF formats. A multiplexer deter-
mines which of two digital input streams are used for the digital output conversion process. These
two streams include the PCM OUT data from the audio controller and the ADC recorded output. The
normal analog LINE_OUT signal can be converted to the SPDIF formats by using the internal ADC
to record the “MIX” output, which is the combination of all analog and all digital sources. In the case
of digital controllers with support for four or more channels, the SPDIF output mode can be used to
support compressed 6-channel output streams for delivery to home theater systems. These can be
routed on alternate AC-Link slots to the SPDIF output, while the standard 2-channel output is deliv-
ered as selected by bits D5 and D4 in Register 6E. If the digital controller supports 6 channels, a
SPDIF output with four analog channels can also be configured.
If the Digital Controller has independent DMA engines, SPDIF and Analog can be used simulta-
neously and independently.
The STAC9766/9767 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. This style of PC Beep will eventually replace
the Analog style, thus eliminating the need for a PC Beep pin. Until this feature is widely accepted,
IDT will provide BOTH styles of PC Beep. Both PC Beep styles use Reg 0Ah. Additional information
about Reg0Ah can be found in Section8.1.5: page50.
Analog PC Beep
PC Beep is active on power up and defaults to an un-muted state. The PC-BEEP input is routed
directly to the MONO_OUT, LINE_OUT and HP_OUT pins of the CODEC. Because the PC_BEEP
input drive is often a full scale digital signal, some resistive attenuation of the PC_BEEP input is rec-
ommended to keep the beep tone within reasonable volume levels. The user should mute this input
before using any other mixer input because the PC Beep input can contribute noise to the lineout
during normal operation. This style of PC Beep is related to the AC’97 Specification Rev 2.2. To use
the analog PC Beep, write a value of 00h to bits F[7:0](D[12:5]) to disable generation of the Digital
PC Beep. PV[3:0] (D[4:1]) controls the volume level from 0dB to 45dB of attenuation in 3dB steps.
Digital PC Beep
The Digital PC Beep uses the identical register as the Analog style, Reg 0Ah. This register controls
the level and frequency for the PC Beep. The beep frequency is the result of dividing the 48 KHz
clock by 4 times the number specified in F[7:0], allowing tones from 47Hz to 12 KHz. A value of 00h
written to bits F[7:0] disables the digital PC Beep generation and enables the analog style PC Beep.
The volume control bits, PV[3:0] operate identically to the analog PC Beep mode. Applying a signal
to the PC Beep pin, pin 12, may cause the digital PC Beep signal to become distorted or inaudible.
When using the digital PC Beep feature, leave the PC Beep input pin unconnected or connected to
analog ground through a capacitor. Connecting a capacitor from the PC Beep input pin to ground will
create a more pleasing sound by changing the digital output to a more sinusoidal output.
44
STAC9766/9767
PC AUDIO
V 7.4 12/06