Datasheet MH89791 Datasheet (MITEL)



MH89791

CEPT PCM 30 Transmit Equalizer

Advance Information

Features

• Used with th e MH8 9790B

• Programmab le equ al ization for differen t line
lengths

• 6dB loop around circuit

Description

The MH89791 is a programmable network for use
with a PCM 30 line interface, specifically the
MH89790B on The ISDN EXPRESS™ Card. The
MH89791 contains transmit equalizer and a 6 dB
pad, for external loop around, with 120Ω input and
output impedances. It is fabricated in thick film
hybrid technology and is 2 inches high by 0.5 inches
wide. The MH89791 is designed to interface to 22
gauge/.6 mm twisted pair. Figure 1 shows how the
MH89791 is connected to the transmit side of a PCM
30 interface. The seven switches control the
distance settings of the equalizer. Ti, Ri, TL, and RL
are the inputs and outputs of the 6 dB pad. The 4
pole doub l e thro w relay conne c ted to the tr an sformer
inputs and outputs shows how the transmit signal is
switched be tween the equalizer for normal operation,

ISSUE 4 May 1995

Pin Connections

1

TL

2

TL

3

TI

4

Ri

5

RL

6

RL

7

TxT

8

EIT

9

EA

10

L1

11

EB

12

EC

13

L2

TxR

EIR

SW

14
15
16
17
18
19
20

RCHT

RCLT

RCHR

RCLR

Ordering Info rmatio n -40°C to 85 °C

MH89791 20 Pin SIP Hybri d

and the 6dB pad for loop arou nd. Figur e 2 shows the
circuit description of the MH89791 while Figure 3
shows the switch settings for the Tx equalizer.

MH89790B

OUTA

OUTB

RxT

RxR

+12V

C2

L1

MH89791

•

•

1:

:0.5

1:

•

•

S1
S2

•

•

S3

S4

•

S5
S6

S7

EIT
EIR

EA
EB

EC
SW

RCLT
RCHT

RCLR
RCHR
Ti
Ri

TxT

TxR

C2 = .47µF
L1 = 33 µH

TL

RL

•

.8:

:1

.8:

•

Figure 1 - Connection Diagram

4-219

MH89791 Advance Information

240Ω

EQUALIZER

S5

•

3600pF

•

S4

•

•

468Ω

1600pF

•

6dB Pad

Tip O

Ring O

•

EiT TxT

60Ω

60Ω

Tip

••

Line

60Ω

•

120Ω

•

60Ω

•

60Ω

•

60Ω

Ring

Line

EiR TxR

•

60Ω

60Ω

•

60Ω

•

120 Ω

••

134.4Ω

6.8µH

S1

•

•

60Ω

60Ω

•

1600 pF

•

152. 4Ω

15µH

S3S2

60Ω

•

S6

•

468Ω

3600 pF

•

-=SWITCH OPENED
X=SWITCH CLOSED

4-220

•

S7

240Ω

•

Figure 2 - M H8979 1 Cir cuit Des crip tion

-

-

-

-

-

X

-

-

X

-

X

X

-

-

-

X
X

-

X

-

X

X

X

S1

X

--

S2

-X

S3

-

S4

-

S5

-

S6

-

S7

-

NO EQUALIZATION MAX. EQUALIZATION

-

-X

-X

-

-

-

-

-

-

-

X

-

-

-

X

-

-

X

X

-

­INCREASING EQUALIZAT ION

Figure 3 - Swi tch Settin gs for Diffe rent Lev els of Eq ualization

-

-

X

-

X

-

X

X

-

-

X
X

X
X

--

X

X
X

X
X

-

-

X
X

X
X
X

Advance Information MH89791

AA

0.03 Max .
(0.8 Max.)

Pin 1

Side
View

0.010 +

0.002

(0.25 + 0.05)

0.2 Max.

(5.1 Max.)

Notes:

1) Not to scale.

2) Dimensions in inches

3) (Dimensions in millim eter s)

4) Dimension to center of pin

0.05 ± 0.01
(1.3 ± 0.3)

2.00 + 0.02

(50.8 + 0.5)

1 5 10 15 20

Front
View

15

*

0.05 +
(1.3 +

0.02

0.5)

0.020 +
(0.51 +

0.00 5

0.13)

0.10 +
(2.5 +

0.01

0.2)

Figure 4 - Mechanical Data

0.02

0.40 +
(10.2 + 0.5 )

0.18 +
(4.6 + 0.5)

0.02

4-221

MH89791 Advance Information

NOTES:

4-222