PC Audio Codecs Comply With Latest Revision Of AC'97 Specs

A trio of ICs that comply with the latest AC'97 Rev. 2.1 specifications have been added to the company's growing lineup of PC audio codecs. The WM9704M, WM9704Q and WM9703 codecs are 18-bit devices offered in 48-pin TQFPs. The devices are fully operable on 3.3V, 5V or mixed 3.3V/5V supplies. And all three offer a master/slave ID selection function that supports the seamless addition of modem and docking facilities. Audio and modem variable-rate sampling is also included to reduce processor power requirements.The WM9704Q is a four-channel, surround-sound codec for PC audio cards that performs full-duplex, 18-bit codec functions at sampling rates from 8 to 48 KS/s. A four-channel quad mode provides two channels of ADC and DAC plus two additional DAC channels as rear outputs. The six-channel mode configures the device to provide external support for two more stereo outputs through its GPI/O pins.For full-duplex modem and stereo audio applications, the WM9704M also offers variable sampling rates and enables simultaneous modem operation and stereo playback. The device combines four 18-bit DACs with an 18-bit stereo ADC and also provides stereo inputs for line, auxiliary, video and a pseudo-differential CD input to minimize crosstalk. It supports mono inputs and integrates all the necessary mixed-signal circuits for a single-chip modem and audio codec.Suited for motherboard, mobile and other power-sensitive applications, the WM9703 audio codec is a suitable companion for the latest PC I/O chipsets with integrated audio controllers. It uses a sigma-delta architecture and audio circuits to produce greater than 95 dB signal-to-noise ratios. Reference design kits are available for audio/modem riser and mother/daughter cards.