Brief Description
The CMX649 Adaptive Delta Modulation(ADM) Voice Codec provides full duplex ADM, companded (µ/A-law) PCM and linear PCM codec and transcoder functions for cost effecive, low power, wireless voice applications. Selectable modes and algorithms support many applications. Robust ADM coding (e.g. CVSD) reduces host protocol and software burdens, eliminating forward error correction, framing protocols and algorithm processing. Dual transcode/decode mode supports multichannel applications. Integrated filter responses adjust independent of 16kbps to 128kbps codec data rates. Codec sample clocks are externally applied or internally generated. High performance analog interfaces and sidetone include digital gain controls. Encoder and decoder voice activity detectors support powersaving.
The CMX649 ADMVoice Codec supports 2.7V to 5.5V operation and is available in 20-pin SOIC (D3) and TSSOP packages (E3) packages.

FEATUREs
·  Multiple Codec Modes, 16 to 128 kbps
--   Full duplex ADM and CVSD
--   Full duplex PCM: µ-law, A-law, Linear
--   Configurable ADM time constants
--   Dual channel transcoder/decoder mode
·  High Performance Digital Architecture
·  Low Power: 2.5mA at 3.0V typ.
·  2.7V - 5.5V Supply
·  Data Clock Recovery
·  Programmable Voice Activity Detector (VAD)
--   Adjust threshold level and attack/decay time
--   Use to powersave on low signal level
--   Silence/blank low level signals
·  Programmable Digital Scrambler
·  Flexible Interfaces
--   8-bit and 16-bit burst data with sync strobe
--   1 bit serial data with clock
--   Host serial control/data interface
·  Internal and External Sample Clocking
·  Programmable Filters
--   Encoder mic input ADC anti-alias
--   Decoder audio out DAC anti-imaging
·  Low Noise Differential Mic Input Amp
·  Programmable Analog Interface Gain
--   Microphone in
--   Decoder audio out
--   Sidetone path

Applications
·  Low Cost Digital Cordless Headset
·  Personal Area Network (PAN) Voice Link
·  Digital Cordless Telephone
·  Wireless Digital PBX
·  Full Duplex Digital Radio Systems
·  Time Division Duplex (TDD) Systems
·  Portable Digital Voice Communicator
·  Digital Voice Delay