CMX649 查看數據表（PDF） - CML Microsystems Plc

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CMX649

ADM Codec

CML Microsystems Plc 

CML Microcircuits

COMMUNICATION SEMICONDUCTORS

CMX649

ADM Codec

D/649/2 May 2003

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

Provisional Issue

• 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

XTAL/

Clock

XTAL

Osc

Analog

Input

MIC

AMP

Analog

Output

Clock

Gen

sidetone

+

ENCODER

PCM

Tx VAD Transcode Buffer Scramble

ADM

Transcoded Data

& Status

Data &

Sample

Clocks

Serial

I/O

serial

control

& data

ADM

Rx VAD Transcode Buffer

PCM

Descramble

Data & Clock

Recovery

DECODER

Data &

Sample

Clocks

TX data

Control

RX data

1. 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 ADM Voice Codec supports 2.7V to 5.5V operation and is available in 20-pin SOIC (D3)

and TSSOP packages (E3) packages.

© 2003 CML Microsystems Plc

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