Dual CODEC chip features echo and noise cancellation

2005-03-01

The MSM7731 is a dual CODEC chip that integrates acoustic and line-side analogue interfaces with both echo and noise cancellation. Designed for hands-free communications systems, it is equipped with grain and mute controls for data transmission and reception, a µ-law PCM/16-bit linear digital interface for memo recording and message output, and a transfer clock generator for digital communications.

An integral analogue input amplifier offers a maximum gain of 30dB and the analogue output is a push-pull configuration designed to drive a 1.2K Ohms load. The MSM7731 also features a built-in transmit slope filter.

The chip operates from a single 3V power supply. Echo attenuation is typically 35dB for white noise and signal noise attenuation is 17dB for white noise and 40dB for single tone. The built-in CODEC provides synchronous transmission and reception, permitting full duplex operation.

The MSM7731 features low power consumption with a typical operating current of 35mA at VDD=3.0V, falling to 0.02mA in standby mode. The device can be controlled via serial or parallel port interfaces.

Operating at a master clock frequency at 19.2MHz, the chip is housed in a 64-pin QFP package.