MT8985

2-52

Figure 7 - Typical Exchange, PBX or Multiplexer Configuration

S/U

Basic Rate Line Card

MT8930/31

MT8910

MT8972

ST-BUS

To other lines

Layers

2 & 3

Entity

MT8940/

MT8941

ROUTING

MATRIX

MT8985’s

MH89760/

MH89790

MT8920

µC

ST-BUS

ST-BUS

T1/E1

Link

To other lines

Primary Rate Card

C

P

U

During the microprocessor initialization routine, the

microprocessor should program the desired active

paths through the matrices, and put

all other

channels into the high impedance state. Care should

be taken that no two connected ST-BUS outputs

drive the bus simultaneously. When this process is

complete,

the

microprocessor

controlling

the

matrices can bring the ODE signal high to relinquish

Applications

Typical Exchange, PBX or Multiplexer

Figure 7 shows a typical implementation of line cards

being interconnected through a central routing matrix

that

can

scale

up

in

channel

capacity

to

accommodate different number of ports depending

on the application. In a configuration where the

switched services utilize concatenated or grouped

time slots to carry voice, data and video (channels of

128, 256 Kb/s, ISDN H0 and others), the central

routing matrix has to guarantee constant throughput

delay to maintain the sequence integrity between

input and output channels.

Figure 7 shows an

example where the MT8985 device guarantees data

integrity when data flows from the T1/E1 to the S/U

interface links and vice-versa. Modern technologies

available today such as Frame Relay network using

dedicated

fractional

T1

are

one

of

the

key

applications for the MT8985 device.

Low Latency Isochronous Network

In today's local working group environment, there is

an

increasing

demand

for

solutions

on

interconnection of desktop and telephone systems

so that mixed voice, data and video services can be

grouped together in a reliable network allowing the

deployment

of

multimedia

services.

Existing

multimedia applications require a network with