82801DB Datasheet, PDF (230/587 Pages) Intel Corporation – Intel 82801DB I/O Controller Hub 4 (ICH4)

Functional Description
5.19.2 AC-Link Overview
The ICH4 supports the AC ’97 2.3 controller that communicates with companion codecs via a
digital serial link called the AC-link. All digital audio/modem streams and command/status
information is communicated over the AC-link.
The AC-link is a bi-directional, serial PCM digital stream. It handles multiple input and output data
streams, as well as control register accesses, employing a time division multiplexed (TDM)
scheme. The AC-link architecture provides for data transfer through individual frames transmitted
in a serial fashion. Each frame is divided into 12 outgoing and 12 incoming data streams, or slots.
The architecture of the ICH4 AC-link allows a maximum of three codecs to be connected.
Figure 5-21 shows a three codec topology of the AC-link for the ICH4.
Figure 5-21. AC ’97 2.3 Controller-Codec Connection
Intel^® ICH4
AC_RST#
AC_SDOUT
AC_SYNC
AC_BIT_CLK
AC_SDIN2
AC_SDIN1
AC_SDIN0
AC / MC / AMC
Primary Codec
AC / MC / AMC
Secondary Codec
AC / MC / AMC
Tertiary Codec
230
Intel^® 82801DB ICH4 Datasheet