MH8981DP Ver la hoja de datos (PDF) - Mitel Networks

Número de pieza

componentes Descripción

Fabricante

MH8981DP

ISO-CMOS ST-BUS™ FAMILY Digital Switch

Mitel Networks 

MT8981D ISO-CMOS

Controlling

Micro-

Processor

Speech

Switch

-

8981

Control &

Signalling

-

8981

4

STi0-3

4

STo0-3

STo0-3

4

STi0-3

4

Line Interface Circuit

with Codec (e.g. 8964)

Line 1

•

•

•

Repeated for Lines

2 to 127

•

•

•

Repeated for Lines

2 to 127

Line Interface Circuit

with Codec (e.g. 8964) Line 128

Figure 8 - Example Architecture of a Simple Digital Switching System

Application Circuit with 6802 Processor

Fig. 10 shows an example of a complete circuit

which may be used to evaluate the chip.

For convenience, a 4 MHz crystal oscillator has been

used rather than a 4.096 MHz clock, as both are

within the limits of the chip’s specifications. The RC

delay used with the 393 counters ensures a

sufficient hold time for the FP signal, but the values

used may have to be changed if faster 393 counters

become available.

The chip is shown as memory mapped into the

MEK6802D3 system. Chip addresses 00-3F

correspond to processor addresses 2000-203F.

Delay through the address decoder requires the

VMA signal to be used twice to remove glitches. The

MEK6802D3 board uses a 10KΩ pullup on the MR

pin, which would have to be incorporated into the

circuit if the board was replaced by a processor.

IN 0/3

8981

#1

STi0/3 STo0/3

OUT 0/3

8981

#2

STi0/3 STo0/3

OUT 4/7

IN 4/7

8981

#3

STi0/3 STo0/3

8981

#4

STi0/3 STo0/3

Figure 9 - Four 8981s Arranged in a Non-Blocking 8 x 8 Configuration

2-24

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