Download Communications IC Selection Guide

RF
Digital Voice Products
CMX649 Adaptive Delta Modulation (ADM) Voice Codec
Analogue Two-way Radio
and Digital PMR/LMR
Full Duplex ADM, CVSD and PCM for Cordless Applications
Features
The CMX649 Adaptive Delta Modulation (ADM) voice codec provides full duplex ADM, μ-law,
A-law, and linear PCM codec and transcoder functions for cost effective, low power, wireless
voice applications.
Wireless
Data
Marine Safety
and Comms
 Multiple Codec Modes: 16 to 128 kbps
 ADM and CVSD, PCM: A-Law,
μ-Law and Linear
 Programmable Time Constants for
ADM Codec
 Dual Channel Transcoder/Decoder
Functions
 On-chip Programmable Anti-alias and
Anti-image Filters
 Programmable Analogue Inputs
and Outputs
 Data Clock Recovery
 Programmable Digital Scrambling and
Voice Activity Detector (VAD)
 Flexible Data Interfaces:
 8 and 16 bit Burst Data + Sync
Strobe
 1 bit Serial Data with Clock
 Host Serial Control and Data
 Supply Requirement Range:
2.7 to 5.5 V
Selectable operating modes and algorithms support many applications. Robust ADM coding
(CVSD) reduces host protocol and software burdens, eliminating forward error correction,
framing protocols and algorithm processing. The dual transcode/decode mode supports multichannel applications.
Integrated audio filter responses adjust independently from the codec’s 16 to 128 kbps data
rates. Codec sample clocks are externally applied or internally generated.
High performance analogue interfaces and sidetone include digital gain controls. Encoder and
decoder voice activity detectors (VAD) support powersaving.
Applications
Digital Voice
Digital Headsets and Telephones
Personal Area Networks (PAN)
Wireless Digital PBXs
Digital Radio Systems
Time-Division Duplex (TDD) Systems
Voice Storage and Voice Delay
MIC AMP
ENCODER
AUDIO IN
Adaptive Delta
Modulation
PCM
scrambler
select algorithm
(CVSD
supported @
64kbps)
sidetone
gain
select µlaw, A-law
or linear
Tx data
and status
serial
interface
TX DATA
SIGNALS
SERIAL
CONTROL
data buffer
Custom
Custom
Transcoded data
and status
DECODER
+
Adaptive Delta
Modulation
Embedded
Embedded
Rx
powersave
select algorithm
(CVSD
supported @
64kbps)
XTAL
oscillator
Rx VAD
internal clock
generator
RX DATA
SIGNALS
PCM
descrambler
select µlaw, A-law
or linear
transcode adaptive delta
modulation to linear PCM
Nominal XTAL
frequencies (MHz)
4.0 - 16.384
data buffer
data & clock
recovery
Internal data clock rates
16k, 24k, 32k, 40k, 48k,
56k, 64k, 128k
Brief CMX649 Technical Basics
Wireline
Data and Telephony
Typical Supply Current at 2.7 to 5.5 V
Powersave
Encoder Analogue Signal Input Levels
Decoder Analogue Signal Output Levels
Encoder/Decoder (Full Codec) Passband
Lowest Corner Frequency
Highest Corner Frequency
Encoder/Decoder (Full Codec) Stopband
Lowest Corner Frequency
Highest Corner Frequency
70
Support
 DE6491 DemoKit
Tx VAD
AUDIO
OUT
Packages
CMX649D3
20-pin SOIC
CMX649E3
20-pin TSSOP
Operating Temperature -40 to +85 ºC
min
-37.0
-37.0
-
typ
2.4
2.5
(programmable)
2900
1400
(programmable)
6.0
24.0
max
2.9
20.0
40.0
40.0
mA
μA
dB
dB
-
Hz
Hz
-
kHz
kHz