82801DB Datasheet, PDF (35/587 Pages) Intel Corporation – Intel 82801DB I/O Controller Hub 4 (ICH4)

Introduction
AC ’97 2.3 Controller
The Audio Codec ’97, Revision 2.3 specification defines a digital interface that can be used to
attach an audio codec (AC), a modem codec (MC), an audio/modem codec (AMC) or a
combination of ACs and MC. The AC ’97 specification defines the interface between the system
logic and the audio or modem codec, known as the AC-link.
By using an audio codec, the AC-link allows for cost-effective, high-quality, integrated audio on
Intel’s chipset-based platform. In addition, an AC ’97 soft modem can be implemented with the use
of a modem codec. Several system options exist when implementing AC ’97. The ICH4-integrated
digital link allows several external codecs to be connected to the ICH4. The system designer can
provide audio with an audio codec, a modem with a modem codec, or an integrated audio/modem
codec. The digital link is expanded to support three audio codecs or two audio codecs and one
modem codec.
The modem implementations for different countries must be taken into consideration, because
telephone systems may vary. By using a split design, the audio codecs can be on-board and the
modem codec can be placed on a riser.
The digital link in the ICH4 supports the Audio Codec ’97, Revision 2.3 specification, so it
supports three codecs with independent PCI functions for audio and modem. Microphone input and
left and right audio channels are supported for a high quality, two-speaker audio solution. Wake on
Ring from Suspend also is supported with the appropriate modem codec.
The ICH4 expands the audio capability with support for up to six channels of PCM audio output
(full AC3 decode). Six-channel audio consists of Front Left, Front Right, Back Left, Back Right,
Center, and Subwoofer, for a complete surround-sound effect. ICH4 has expanded support for three
audio codecs on the AC-link.
Intel^® 82801DB ICH4 Datasheet
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