DESCRIPTION

The DS2165Q ADPCM processor chip is a dedicated digital-signal-processing (DSP) chip that has been optimized to perform adaptive-differential pulse-code modulation (ADPCM) speech compression at three different rates. The chip can be programmed to compress (expand) 64kbps voice data down to (up from) either 32kbps, 24kbps, or 16kbps. The compression to 32kbps follows the algorithm specified by CCITT Recommendation G.721 (July 1986) and ANSI document T1.301 (April 1987). The compression to 24kbps follows ANSI document T1.303. The compression to 16kbps follows a proprietary algorithm developed by Dallas Semiconductor. The DS2165Q can switch compression algorithms on-the-fly. This allows the user to make maximum use of the available bandwidth on a dynamic basis.

FEATURES

■ Compresses/expands 64kbps PCM voice to/from either 32kbps, 24kbps, or 16kbps

■ Dual fully independent channel architecture; device can be programmed to perform either:

- two expansions

- two compressions

- one expansion and one compression

■ Interconnects directly to combo-codec devices

■ Input to output delay is less than 375s

■ Simple serial port used to configure the device

■ On-board time-slot assigner-circuit (TSAC) function allows data to be input/output at various time slots

■ Supports Channel Associated Signaling

■ Each channel can be independently idled or placed into bypass

■ Available hardware mode requires no host processor; ideal for voice storage applications

■ Single +5V supply; low-power CMOS technology

■ Available in 28-pin PLCC

■ 3V operation version is available (DS2165QL)