4-229

Features

Complete primary rate 2048kb/s CEPT line
driver and receiver

Onboard pulse transformers for transmit and
receive

Meets latest ETSI requirements [ETSI ETS 300
011 (NET 5)]

Inductorless clock recovery

Loss of signal (LOS) indication

Single +5V operation

Compatible with MT9079 Framer

Selectable termination impedance

Applications

Primary rate ISDN network Interface

Multiplexer equipment

Private Network links

Isochronous LANS/WANS

Description

The Mitel MH89793 is a low cost E1 line
driver/receiver with clock extraction requiring no
external components.

The device is suitable for both 120R and 75R
applications, by linking external pins.

By combining the MH89793 with Mitel's E1 framer,
the MT9079, a cost effective and efficient interface to
E1 lines can be built.

Figure 1 - Functional Block Diagram

TLA

TLB

RLA

RLB

VDD

VSS

TxA
TxB

E2o

RxA

RxB

LOS

Line

Driver

Clock

Recovery

6dB

Pad

EQUIPMENT SIDE

LINE SIDE

RZA

RZB

TZA1 TZA2 TZA3

TZC2

TZD2

TZB1

TZD1

TZB2 TZC1

Line

Receiver

Receive

Isolation

Transformer

Transmit

Isolation

Transformer

ISSUE 1

April 1995

Ordering Information

MH89793 28 Pin DIL Package

Surface Mount Option is available by adding

the suffix "S"

C to +70

MH89793

E1 Transceiver with Selectable Impedance

Preliminary Information

4-230

MH89793

Preliminary Information

Figure 2 - Pin Connections

Pin Description

Pin #

Name

Description

RLA

Received Line A (Input). The A wire or Tip connection of the E1 receive line is connected
to this pin.

RLB

Received Line B (Input). The B wire or Ring connection of the E1 receive line is
connected to this pin.

TLA

Transmit Line B (Output). The A wire or Tip connection of the E1 receive line connected
to this pin.

TLB

Transmit Line B (Output). The B wire or Ring connection of the E1 receive line connected
to this pin.

TZD2

Transmit Impedance Select. This pin is connected to pin 4 TLB to select 75

impedance.

For 120

operation this pin is left open circuit.

TZC2

Transmit Impedance Select. This pin is connected to pin 3 TLA to select 75

impedance.

For 120

operation this pin is left open circuit.

TZA3

Transmit Impedance Select. This pin is connected to pin 9 TZA2 to select 75

impedance. For 120

operation this pin is left open circuit.

TZA3

Transmit Impedance Select. This pin is connected to pin 10 TZB2 to select 120

impedance. For 75

operation this pin is left open circuit.

TZA2

Transmit Impedance Select. This pin is connected to pin 7 TZA3 to select 75

impedance. For 120

operation this pin is left open circuit.

TZB2

Transmit Impedance Select. This pin is connected to pin 8 TZB1 to select 120

impedance. For 75

operation this pin is left open circuit.

TZD1

Transmit Impedance Select. This pin is connected to pin 4 TLB to select 120

impedance. For 75

operation this pin is left open circuit.

TZC1

Transmit Impedance Select. This pin is connected to pin 3 TLA to select 120

impedance. For 75

operation this pin is left open circuit.

TZA1

Transmit Impedance Select. This pin is connected to pin 9 TZA2 to select 120

impedance. For 75

operation this pin is left open circuit.

No Connection. This pin is used for internal connection.

TXA

Transmit A (Input). A unipolar signal from the framer device used in conjunction with TXB
is used to generate the bipolar output signal.

1
2

3
4

10
11

22
23

RLA
RLB

TLA
TLB

TZD2
TZC2
TZA3
TZB1

TZA2
TZB2
TZD1
TZC1

TZA1

TXA
TXB

NC
NC
NC
VDD

E20

RXB

RXA
VSS

LOS
NC
RZA
RZB

4-231

Preliminary Information

MH89793

TXB

Transmit B (Input). A unipolar signal from the framer device used in conjunction with TXA
is used to generate the bipolar output signal.

No Connection. This pin is used for internal connection.

VDD

D.C. Power (Input). +5V supply.

E2o

2048kHz Extraction Clock (Output). This clock is extracted by the device from the
received signal. It is used internally to clock in data received from RLA and RLB.

RXB

Receive B (Output). This pin is connected to the negative receive pin of the framer and
provides a signal of the same format as RXA.

RXA

Receiver A (Output). The bipolar CEPT signal received by the device at RLA and RLB
input is converted to a unipolar format and output at this pin. This pin is connected to the
positive receive pin of the framer.

VSS

Ground (Input). D.C. power return path.

LOS

Loss of Signal (Output). This pin goes low when 128 contiguous zeros are received on
the RLA and RLB inputs. LOS is reset when 64 ones are received in dual E1 frame periods.

No Connection. This pin is used for internal connection.

RZA

Receive Impedance Select. This pin is connected to pin 17 RZB to select 75

input

impedance. For 120

operation this pin is left open circuit.

RZB

Receive Impedance Select. This pin is connected to pin 16 RZA to select 75

input

impedance. For 120

operation this pin is left open circuit.

Pin Description (Continued)

Pin #

Name

Description

Functional Description

The MH89793 is an E1 digital trunk interface which
when used with an approved framer will conform to
CCITT recommendation G.703 for PCM30 and I.431
for the ISDN. The functions provided include line
driver and receiver circuitry, inductorless clock
recovery, and loss of signal indication.

Bipolar Line Receiver

The MH89793 receiver interfaces to the transmission
line through an internal pulse transformer which
splits the received AMI lines signal into RxA and
RxB. The line impedance is selected by linking
appropriate option pins.

Attenuation of the transmission line shall not exceed
6dB (at 1024kHz) and attenuation characteristics
shall be close to the "square root of f".

Af (dB) = AF

ref

(dB)*

ref

Where:
AF - attenuation at frequency f in dB
AF

ref

- attenuation at frequency f

ref

in dB (in kHz)

ref

- reference frequency (in this case 1024) kHz

f - frequency in kHz

Bipolar Line Transmitter

The MH89793 transmitter interfaces to the
transmission line through an internal pulse
transformer which combines the TxA and TxB data
into an AMI line coded signal. This is then passed
through the 6dB pad prior to being applied to the
line.

Clock Extractor

The MH89793 contains a clock extraction circuit that
generates the E2o clock from the received data
without the use of external crystals or a tunable
inductor.

The edge of the E2o extracted clock approximately
aligns with the centre of the received data pulse.

4-232

MH89793

Preliminary Information

Loss of Signal

The circuitry on board the hybrid is capable of
detecting 128 continuous ZEROs received on RLA
and RLB and indicating this condition as a logic low
on pin 9, (LOS). LOS will not reset until 64 ONEs are
received in a two E1 frame period.

Figure 3a - Application Circuit for 75

Operation

VDD

RESET

DSTi

DSTo

F0i

E8Ko

D0-7

AC0-4

R/W

IRQ

S/P

TAIS

TxMF

TxA

TxB

RxA

RxB

E2i

C4i

8-15

18-22

10K

TxA

TxB

RxA

RxB

E2o

RLA

TLA

TLB

RLB

LOS

MH89793

0.1

NETWORK

CONNECTOR

MT9079

TZA1

TZA2
TZA3

TZB1
TZB2

RZA
RZB

TZD1

TDZ2

TZC1

TZC2

10
27
28

MT9042

Foi

C4i

4-233

Preliminary Information

MH89793

Figure 3b - Application Circuit for 120

Operation

VDD

RESET

DSTi

DSTo

F0i

E8Ko

D0-7

AC0-4

R/W

IRQ

S/P

TAIS V

TxMF

TxA

TxB

RxA

RxB

E2i

C4i

8-15

18-22

10K

TxA

TxB

RxA

RxB

E2o

RLA

TLA

TLB

RLB

LOS

MH89793

0.1

NETWORK

CONNECTOR

MT9079

TZA1

TZA2
TZA3

TZB1
TZB2

RZA
RZB

TZD1

TDZ2

TZC1

TZC2

10
27
28

MT9042

Foi

C4i

4-234

MH89793

Preliminary Information

Figure 4 - Mechanical Data for 28 Pin Surface Mount Hybrid

Figure 5 - Recommended Footprint for 28 Pin Surface Mount Hybrid

AAAA

AAA

1.08 Max

(27.4 Max)

0.10 + 0.005

(2.54 + 0.12)

1.42 Max

(36.1 Max)

0.23 Max

(5.9 Max)

0.063 Max

(1.6 Max)

0.37 Max
(9.5 Max)

AAAA

AAA

AAAA

0.125+0.015±

(3.18+0.38)

0.060 Typ

(1.52)

0.050 Typ

(1.27 Typ)

0.020 + 0.005

(0.51 + 0.12)

0.08 Typ (2 Typ)

Notes:
1) Not to scale
2) Dimensions in inches).
3) (Dimensions in millimetres).

*Dimensions to centre of pin.

0.1

(2.5)

0.89
(22.6)

0.04
(1.02)

0.06

(1.53)

Preliminary Information

MH89793

4-235

Figure 6 - Mechanical Data for 28 Pin DIL Hybrid

1.42 Max

(36.1 Max)

0.23 Max (5.9 Max)

0.050 Typ
(1.27 Typ)

0.020 + 0.005

(0.5 + 0.12)

0.063 Max(1.6 Min)

0.26+0.015 (6.6+0.4)

AAAA

AAA

AAAA

AAA

(22.9 Typ)

0.95 Max

(24.2 Max)

0.90 Typ

0.31 Max

(7.9 Max)

0.08 Typ (2 Typ)

0.100+0.005

(2.54+0.12

Notes:
1) Not to scale
2) Dimensions in inches).
3) (Dimensions in millimetres).

*Dimensions to centre of pin.

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