IMP8980D Datasheet, PDF (1/14 Pages) IMP, Inc – PCM Digital Switch

®
ISO 9001 Registered
IMP8980D
PCM Digital Switch
General Description
This CMOS device is designed for
switching PCM-encoded voice or data,
under microprocessor control, in a modern
digital exchange, PBX or Central Office. It
provides simultaneous connections for up
to 256 64kbit/s channels. Each of the eight
serial inputs and outputs consist of 32
64kbit/s channels multiplexed to form a
2048kbit/s ST-BUS stream. In addition,
the IMP8980D provides microprocessor
read and write access to individual
ST-BUS (Serial Telecom Bus) channels.
Features
♦ ST-BUS compatible
♦ 8-line x 32-channel inputs
♦ 8-line x 32-channel outputs
♦ 256 ports non-blocking switch
♦ Single power supply (+5V)
♦ 30mW power consumption
♦ Microprocessor-control interface
♦ Pin-compatible with Mitel MT8980
Functional Description
The ST-BUS architecture can be used
both in software-controlled digital voice
and data switching.
The ST-Bus serial streams operate
continuously at 2048kbit/s and are
arranged in 125µs wide frames which
contain 32 8-bit channels.
The IMP8980D can switch data from
channels on ST-BUS inputs to channels on
ST-BUS outputs and simultaneously
allows its controlling microprocessor to
read channels on ST-BUS inputs or write
to channels on ST-BUS outputs (Message
Mode). To the microprocessor, the
IMP8980D looks like a memory periph-
eral. The microprocessor can write to the
IMP8980D to establish switched connec-
tions between input ST-BUS channels and
output ST-BUS channels or to transmit
messages on output ST-BUS channels. By
reading from the IMP8980D, the micro-
processor can receive messages from
ST-BUS input channels or check which
Figure 1 Functional Block Diagram
C4i F0i
VDD VSS
ODE
STi0
STi1
Serial
STi2
to
STi3
Parallel
STi4
Converter
STi5
STi6
STi7
Data
Memory
Frame
Counter
Control Register
Control Interface
Output
MUX
Connection
Memory
Parallel
to
Serial
Converter
STo0
STo1
STo2
STo3
STo4
STo5
STo6
STo7
DS CS R/W A5/ DTA D7/
A0
D0
CSTo
1