CMOS ST-BUS
TM
Family
MT8985
Enhanced Digital Switch
Data Sheet
Features
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•
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•
•
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256 x 256 channel non-blocking switch
Programmable frame integrity for wideband
channels
Automatic identification of ST-BUS/GCI interface
backplanes
Per channel tristate control
Patented message mode
Non-multiplexed microprocessor interface
Single +5 volt supply
Available in DIP-40, PLCC-44 and QFP-44
packages
Pin compatible with MT8980 device
Ordering Information
September 2005
MT8985AE
40 Pin PDIP
Tubes
MT8985AP
44 Pin PLCC
Tubes
MT8985AL
44 Pin MQFP Trays
MT8985APR 44 Pin PLCC
Tape & Reel
MT8985AP1 44 Pin PLCC* Tubes
MT8985APR1 44 Pin PLCC* Tape & Reel
MT8985AE1 40 Pin PDIP*
Tubes
MT8985AL1 44 Pin MQFP* Trays
*Pb Free Matte Tin
-40°C to +85°C
Switch (DX). It is pin compatible with the MT8980D and
retains all of the MT8980D's functionality. This VLSI
device is designed for switching PCM-encoded voice
or data, under microprocessor control, in digital
exchanges,
PBXs
and
any
ST-BUS/MVIP
environment. It provides simultaneous connections for
up to 256 64 kb/s channels. Each of the eight serial
inputs and outputs consist of 32 64 kbit/s channels
multiplexed to form a 2048 kbit/s stream. As the main
function in switching applications, the device provides
per-channel selection between variable or constant
throughput delays. The constant throughput delay
feature allows grouped channels such as ISDN H0 to
be switched through the device maintaining its
sequence integrity. The MT8985 is ideal for medium
sized mixed voice/data switch and voice processing
applications.
Applications
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Medium size digital switch matrices
Hyperchannel switching (e.g., ISDN H0)
ST-BUS/MVIP
™
interface functions
Serial bus control and monitoring
Centralized voice processing systems
Data multiplexer
Description
The MT8985 Enhanced Digital Switch device is an
upgraded version of the popular MT8980D Digital
C4i
F0i
V
DD
V
SS
ODE
STi0
STi1
STi2
STi3
STi4
STi5
STi6
STi7
Serial
to
Parallel
Converter
Data
Memory
Frame
Counter
Output
MUX
Parallel
to
Serial
Converter
STo0
STo1
STo2
STo3
STo4
STo5
STo6
STo7
Control Register
Connection
Memory
Control Interface
DS CS
R/W A5/
A0
DTA D7/
D0
CSTo
Figure 1 - Functional Block Diagram
1
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