®
MH88634
Central Office Interface Circuit
Preliminary Information
Features
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Loop Start Trunk Interface
600 ohm input impedance, -2 variant
Line state detection outputs: forward loop,
reverse loop, ringing voltage, switch hook
On-hook reception
Transformerless 2W to 4W conversion
One loop start relay driver
+/- 5V operation
Small footprint area (<4.75cm
2
)
MH88634-2
ISSUE 2
April 1995
Ordering Information
21 Pin SIL Package
0°C to 70°C
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Description
The Mitel MH88634 Central Office Trunk Interface
circuit provides a complete audio and signalling link
between audio switching equipment and a central
office. The functions provided by the MH88634
include 2-4 Wire conversion, 600 ohm input
impedance and network balance. The device is
fabricated as a thick film hybrid incorporating various
technologies for optimum circuit design and very
high reliability.
Applications
Interface to Central Office for:
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PABX
Key Telephone Systems
Channel Bank
Voice Mail
Terminal Equipment
Digital Loop Carrier
Optical Multiplexer
RING
TIP
VDD VEE AGND RV
FL
RL
SHK
Dummy
Ringer
Status
Detection
XLA
XLB
XLC
XLD
LRC
LRD
Loop
Termination
2-4 Wire Hybrid
Loop Relay
Driver
Impedance
Matching
Network
Balance
Receive
Gain
Rx
Transmit
Gain
Tx
VRLY
RGND
Figure 1 - Functional Block Diagram
2-253