MT8976AP datasheet(17/26 Pages) MITEL

17 / 26 page

ISO-CMOS

MT8976

4-45

compatible equipment (see ANSI T1.102 and AT & T

Technical Advisory #34).

On the receive side the

bipolar

line signal is converted

into a unipolar

format by the line receiver

circuit.

The resulting

split phase signals are input at the RxA and RxB pins

on the MT8976. The signals are combined together

to produce a composite return to zero signal, which

is clocked into the device at RxD. An uncommitted

nand gate in the MT8940/41 can be used for this

purpose.

The MT8976 can be interfaced to a high speed

parallel bus or to a microprocessor using the

MT8920B Parallel Access Circuit (STPA). Figure 11

shows the MT8976 interfaced to a parallel bus

structure using two STPA‘s operating in modes 1 and

The first STPA operating in mode 2 (MMS=0,

MS1=1, 24/32=0),

routes

data

and/or

voice

information between the parallel telecom bus and the

T1 or CEPT link via DSTi and DSTo.

The second

STPA, operating in mode 1 (MMS = 1 ) provides

access from the signalling and link control bus to the

MT8976 status and control channels. All signalling

and link functions may be controlled easily through

the STPA transmit RAM’s Tx0, Tx1,

while status

information is read at receive RAM Rx0. In addition,

interrupts can be set up to notify the system in case

of slips, loss of sync, alarms, violations, etc.

Mitel also manufactures a thick film hybrid device,

the MH89760/760B, which incorporates the line

driver, receiver and clock extractor circuitry.

second SIP hybrid, the MH89761, provides the

necessary equalization circuitry to condition the

signal for transmission up to 655 feet over 22 AWG

twisted pair.

Note: the configurations shown in Figures 10 and 11

using the MT8940/41 may not meet specific jitter

performance requirements.

A more sophisticated

PLL

line

interface

unit

with

transmit

jitter

attenuator may be required for applications designed

to meet specific standards.

Figure 11 - Using the MT8976 in a Parallel Bus Environment

HIGH

SPEED

PARALLEL

TELECOM

BUS

MT8920B

(Mode 2)

D0-D7

A0-A5

R/W

MMS MS1 24/32

STo0

STi0

STo1

C4i

F0i

MT8976

D0-D7

A0-A5

R/W

DTACK

IRQ

lACK

MMS

+5V

E8Ko

RxD

RxB

RxA

TxB

TxA

E1.5i

C1.5i

C2i

F0i

CSTi1

CSTo

CSTi0

DSTo

DSTi

Clock

Extractor

Line

Driver

Line

Receiver

DIP

SWITCH

EQU

MT8940/41

MT8940/

MT8941

CVb

F0i

C2o

F0b

C4b

C8Kb

12.355/12.352

MHz Osc.

16.388/16.384

•

1.544

STo0

STi0

STo1

C4i

F0i

MT8920B

(Mode 1)

SIGNALLING

and

LINK

CONTROL

BUS

MH89761

MHz

MT8976AP Datasheet(PDF) 17 Page - Mitel Networks Corporation

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