MITEL MH89793 Datasheet

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MH89793

E1Transceiver with Selectable Impedance

Preliminary Info rmatio n

Features

• Complet e primary ra te 20 48kb /s CEPT line driver and re ceiver

• Onboard pul se tran sform ers for transm it and receive

• Meets lates t E T S I req uirements [ET S I ETS 300 011 (NET 5)]

• Inductorless clock recovery

• Loss of signal (LOS

) indication

• Single +5 V ope ration

• Compatible with MT9079 Fra mer

• Selectable termin atio n imped anc e

Applications

• Primary rate ISDN network Interface

• Multiplexe r equ ipm ent

• Private Network links

• Isochrono us LA NS/WANS

ISSUE 1 April 1995

Ordering Information

MH89793 28 Pin DIL P ackage

Surface Mount Option is available by adding

the suffix “S”

0°C to +70°C

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.

TxA TxB

E2o LOS

RxA RxB

VDD

Recovery

Receiver

VSS

Line

Driver

Clock

Line

EQUIPMENT SIDE

TZA1 TZA2 TZA3 TZC2 TZD2TZB1 TZD1TZB2 TZC1

Transmit

Isolation

Transformer

Receive Isolation

Transformer

LINE SIDE

Figure 1 - Functional Blo ck Diag ram

6dB

Pad

RZA RZB

TLA TLB

RLA RLB

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MH89793 Preliminary Information

RLA RLB

TLA

TLB TZD2 TZC2 TZA3 TZB1 TZA2 TZB2

TZD1 TZC1 TZA1

1 2 3 4

7 8

9 10 11

12 13

15 16 17 18 19 20 21 22 23

TXA TXB

NC NC NC VDD

E20

RXB

RXA VSS

LOS

RZA

RZB

Figure 2 - Pin Connections

Pin Description

Pin # Name Description

1RLAReceived Li ne A (Inp ut). The A wire or Tip connection of the E1 receive line is connected

to this pin .

2RLBReceived Line B (In put). The B wire or Ring connection of the E1 receive line is

connected to this pin.

3TLATransmit Line B (Output). The A wire or Tip connection of the E1 receive line connected

to this pin .

4TLBTransmit Line B (Output). The B wire or Ring connection of the E1 receive line connected

to this pin .

5TZD2Transmit Impedance Select. This pin is connected to pin 4 TLB to select 75Ω impedance.

For 120Ω operation this pin is left ope n circuit.

6TZC2Transmit Impedance Select. This pin is connected to pin 3 TLA to select 75Ω impedance.

For 120Ω operation this pin is left ope n circuit.

7TZA3Transmit Impedance Select. This pin is connected to pin 9 TZA2 to select 75Ω

impedance. For 120Ω operation this pin is left open circuit.

8TZA3Transmit Impedance Select. This pin is connected to pin 10 TZB2 to select 120Ω

impedance. For 75Ω operation this pin is left open circuit.

9TZA2Transmit Impedance Select. This pin is connected to pin 7 TZA3 to select 75Ω

impedance. For 120Ω operation this pin is left open circuit.

10 TZB2 Transmit Impedance Select. This pin is connected to pin 8 TZB1 to select 120Ω

impedance. For 75Ω operation this pin is left open circuit.

11 TZD1 Transmit Impedance Select. This pin is connected to pin 4 TLB to select 120Ω

impedance. For 75Ω operation this pin is left open circuit.

12 TZC1 Transmit Impedance Select. This pin is connected to pin 3 TLA to select 120Ω

impedance. For 75Ω operation this pin is left open circuit.

13 TZA1 Transmit Impedance Select. This pin is connected to pin 9 TZA2 to select 120Ω

impedance. For 75Ω operation this pin is left open circuit. 14 NC No Connection. This pin is used for internal connection. 15 TXA Transmit A (Input). A unipolar signal from the framer device used in conjunction with TXB

is used to generate the bipolar output signal.

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Preliminary Information MH89793

Pin Description (Continued)

Pin # Name Des crip tio n

16 TXB Transmit B (Input). A unipolar signal from the framer device used in conjunction with TXA

is used to generate the bipolar output signal. 17 NC No Connection. This pin is used for internal connection. 18 NC No Connection. This pin is used for internal connection. 19 NC No Connection. This pin is used for internal connection. 20 VDD D.C. Power (Input). +5V supply. 21 E2o 2 048kHz Ex tractio n Clock (Ou tput). This clock is extracted by the device from the

received signal. It is used internally to clock in data received from RLA and RLB. 22 RXB Receive B (Output). This pin is connected to the negative receive pin of the framer and

provides a signal of the same form at as RXA. 23 RXA Receiver A (Outpu t ). 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. 24 VSS Ground (Input). D.C. power retu rn path. 25 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. 26 NC No Connection. This pin is used for internal connection. 27 RZA Receive Impedance Select. This pin is connected to pin 17 RZB to select 75Ω input

impedance. For 120Ω operation this pin is lef t ope n circuit .

28 RZB Receive Impedance Select. This pin is connected to pin 16 RZA to select 75Ω input

impedance. For 120Ω operation this pin is lef t ope n circuit .

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 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.

Bipolar Line Receiver

Clock Extractor

The MH89793 receiver inter faces to the trans miss ion 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”.

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.

Af (dB) = AF

Where:

(dB)* √f

ref

AF - attenuation at frequency f in dB

- attenuation at frequency f

ref

- reference frequency (in this case 1024) kHz

ref

in dB (in kHz)

ref

f - frequenc y i n k H z

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