STAC9752 datasheet(82/95 Pages) IDT

82 / 95 page

STAC9752/9753

TWO-CHANNEL, 20-BIT, AC’97 2.3 CODECS WITH HEADPHONE DRIVE, SPDIF OUTPUT MICROPHONE & JACK SENSING

IDT™

STAC9752/9753

REV 3.3 1206

TWO-CHANNEL, 20-BIT, AC’97 2.3 CODECS WITH HEADPHONE DRIVE, SPDIF OUTPUT MICROPHONE & JACK SENSING

10. MULTIPLE CODEC SUPPORT

The STAC9752/9753 provides support for the multi-CODEC option according to the Intel AC'97, rev

2.3 specification. By definition, there can be only one Primary CODEC (CODEC ID 00) and up to

three Secondary CODECs (CODEC IDs 01,10, and 11). The CODEC ID functions as a chip select.

Secondary devices therefore have completely orthogonal register sets; each is individually accessi-

ble and they do not share registers.

10.1. Primary/Secondary CODEC Selection

In a multi-CODEC environment the CODEC ID is provided by external programming of pins 45 and

46 (CID0 and CID1). The CID pin electrical function is logically inverted from the CODEC ID desig-

nation. The corresponding pin state and its associated CODEC ID are listed in the “CODEC ID

Selection” table.

10.1.1.

Primary CODEC Operation

As a Primary device, the STAC9752/9753 is completely compatible with existing AC'97 definitions

and extensions. Primary CODEC registers are accessed exactly as defined in the AC'97 Component

Specification and AC'97 Extensions. The STAC9752/9753 operates as Primary by default, and the

external ID pins (45 and 46), have internal pull-ups so that these pins may be left as no-connects for

operation as a primary.

When used as the Primary CODEC, the STAC9752/9753 generates the master AC-Link BIT_CLK

for both the AC'97 Digital Controller and any Secondary CODECs. The STAC9752/9753 can support

up to four loads of 10 K

Ω and 50 pF on the BIT_CLK output. This is to ensure that up to four CODEC

implementations will not load down the clock output.

10.1.2.

Secondary CODEC Operation

When the STAC9752/9753 is configured as a Secondary device the BIT_CLK pin is configured as an

input at power up. Using the BIT_CLK provided by the Primary CODEC insures that everything on

the AC-Link will be synchronous. As a Secondary device it can be defined as CODEC ID 01, 10, or

11 in the two-bit field(s) of the Extended Audio and/or Extended Modem ID Register(s).

Table 28. CODEC ID Selection

CID1 State

CID0 State

CODEC ID

CODEC Status

Dvdd or floating

Primary

Dvdd or floating

0 V

Secondary

0 V

Dvdd or floating

Secondary

0 V

Secondary

STAC9752 Datasheet(PDF) 82 Page - Integrated Device Technology

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