MT9126 Datasheet, PDF (1/22 Pages) Mitel Networks Corporation – CMOS Quad ADPCM Transcoder

CMOS MT9126
®
Quad ADPCM Transcoder
Preliminary Information
Features
• Full duplex transcoder with four encode
channels and four decode channels
• 32 kb/s, 24 kb/s and 16 kb/s ADPCM coding
complying with ITU-T (previously CCITT) G.726
(without 40 kb/s), and ANSI T1.303-1989
• Low power operation, 25 mW typical
• Asynchronous 4.096 MHz master clock
operation
• SSI and ST-BUS interface options
• Transparent PCM bypass
• Transparent ADPCM bypass
• Linear PCM code
• No microprocessor control required
• Simple interface to Codec devices
• Pin selectable µ−Law or A-Law operation
• Pin selectable ITU-T or signed magnitude PCM
coding
• Single 5 volt power supply
Applications
• Pair gain
• Voice mail systems
• Wireless telephony systems
ISSUE 2
Ordering Information
MT9126AE 28 Pin Plastic DIP
MT9126AS 28 Pin SOIC
-40 °C to +85 °C
May 1995
Description
The Quad ADPCM Transcoder is a low power,
CMOS device capable of four encode and four
decode functions per frame. Four 64 kbit/s PCM
octets are compressed into four 32, 24 or 16 kbit/s
ADPCM words, and four 32, 24 or 16 kbit/s ADPCM
words are expanded into four 64 kbit/s PCM octets.
The 32, 24 and 16 kbit/s ADPCM transcoding
algorithms utilized conform to ITU-T
Recommendation G.726 (excluding 40 kbit/s), and
ANSI T1.303 - 1989.
Switching, on-the-fly, between 32 kbit/s and 24 kbit/s
ADPCM, is possible by controlling the appropriate
mode select (MS1 - MS6) control pins. All optional
functions of the device are pin selectable allowing a
simple interface to industry standard codecs, digital
phone devices and Layer 1 transceivers. Linear
coded PCM is provided to facilitate external DSP
functions .
ADPCMi
ADPCMo
ENB1
ENB2/F0od
BCLK
F0i
MCLK
C2o
EN1
EN2
Full Duplex
ADPCM
I/O
Quad
Transcoder
PCM
I/O
PCMo1
PCMi1
PCMo2
PCMi2
Timing
Control Decode
VDD VSS PWRDN IC
MS1 MS2 MS3 A/µ FORMAT MS4 MS5 MS6 LINEAR SEL
Figure 1 - Functional Block Diagram
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