MH89791 Datasheet, PDF (1/4 Pages) Mitel Networks Corporation – CEPT PCM 30 Transmit Equalizer Advance Information

MH89791
®
CEPT PCM 30 Transmit Equalizer
Advance Information
Features
• Used with the MH89790B
• Programmable equalization for different 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 double throw relay connected to the transformer
inputs and outputs shows how the transmit signal is
switched between the equalizer for normal operation,
ISSUE 4
Pin Connections
TL ¹
TL ²
TI ³
Ri ⁴
RL ⁵
RL ⁶
TxT 7
EIT 8
EA ⁹
L1 ¹⁰
EB ¹¹
EC 12
L2 ¹³
RCHT ¹⁴
RCLT ¹⁵
TxR 16
EIR 17
SW ¹⁸
RCHR 19
RCLR ²⁰
May 1995
Ordering Information -40°C to 85°C
MH89791
20 Pin SIP Hybrid
and the 6dB pad for loop around. Figure 2 shows the
circuit description of the MH89791 while Figure 3
shows the switch settings for the Tx equalizer.
MH89790B
OUTA
• +12V
L1 1:
OUTB
C2
1:
RxT
.8:
••
:0.5
•
S1
S2
•
S3
• S4
S5
•
S6
S7
MH89791
EIT
TxT
EIR
TxR
EA
EB
EC
SW
RCLT
RCHT
RCLR
RCHR
Ti
Ri
C2 = .47µF
L1 = 33 µH
TL
RL
•
:1
.8:
RxR
•
Figure 1 - Connection Diagram
4-219