Audio Codec '97

AC ‘97 Component Specification Revision 2.3 Rev 1.0

Current voice modem implementations migrate the controller functionality into the modem driver, eliminate the

redundant voice Codec, and rely on low latency digital streaming between the modem and audio drivers.

AMC designs may optionally implement the PHONE and MONO_OUT connections internally to save package pins.

For certification reasons, care should be taken to limit the bandwidth of analog audio signals coupled to the modem

Tx via MONO_OUT.

6.5 Wake-up and Power Management Event (PME#) Support

Ring and handset offhook detect are examples of events that might need to wake-up a PC that has suspended into a

low power state. Wake-up on an audio event could eventually become practical.

Revision 1.x AC ‘97 architecture enables fine granular power management of the AC-link and the individual

subsections within the Codec. However it does not support system wake requests triggered by external events.

Power management, or wake, event support for a modem is a key feature of the Intel® Instantly Available PC power

management architecture and must be fully comprehended by the Extended AC ‘97 architecture. Support for wake-

up must be comprehended for various configurations of AC ‘97 and (A)MC ‘97 , whether for single Codec, or split

partitioned Primary/Secondary Codec implementations.

The Instantly Available PC power management architecture specifies a Vaux supply that is designed to support

specific “always active” functions while the majority of the PC is powered down. 5.0 V

and 3.3 V Vaux supplies

are available on the motherboard, and a 3.3 V Vaux supply pin is currently being added to the PCI slot definition.

The integrity(?) of the Vaux supply will depend on the power supply source.

6.5.1 Combined Audio/Modem AFE Codec (AMC ‘97 )

For AMC ‘97 combined Audio/Modem AFE implementations the Codec, AC-link and portions of the AC ‘97

Digital Controller which provide wake-up functionality, all must be powered by Vaux as illustrated in Figure 21:

Figure 21. Combined Audio / Modem AFE Auxiliary Power Distribution

The Codec and AC-link are programmed to a low power state (see Figure 22) and, upon detection of a power

management event, are brought back to the active state by executing a warm reset sequence as shown in Figure 23.

Figure 22 shows the AC ‘97 Digital Controller placing the AC-link into its lowest power state by programming the

Codec’s Power-down Control/Status Register with bit(12) = 1 (PR4) .

Digital

Controller

SDATA_OUT

SDATA_IN(0)

DAA

BIT_CLK

SYNC

RESET#

PME#

AMC '97

Combo Codec

Analog

Circuitry

Vmain

Note: modem analog circuitry must be powered by Vaux if supporting hardware caller ID

capture during ACPI S3 or S4 power management states.