®
MH88422
Line Interface Circuit
Preliminary Information
Features
•
•
•
•
•
•
•
•
•
•
•
•
FAX and Modem interface (V29/V22 bis)
Variants match German, UK & 600
Ω
network
impedances
Provides reinforced barrier to international PTT
requirements
Transformerless 2-4 Wire conversion
Loop start operation
Pulse and DTMF operation
Accommodates external monitor phone
Line state detection outputs:
-loop current/ringing outputs
Single +5V operation, low idle power (5mW)
Full Duplex
Suitable for power down applications
MH88422-1
MH88422-2
MH88422-3
ISSUE
5
April 1995
Ordering Information
14 Pin DIL Package
14 Pin DIL Package
14 Pin DIL Package
Surface Mount Options are available by adding the
Suffix “S”
Description
The Mitel MH88422 Line Interface Circuit provides a
complete audio and signalling link between audio
equipment and central office. The functions provided
by the MH88422 include 2-4 Wire conversion, loop
seizure, ring voltage and loop current detection. The
device is fabricated as thick film hybrid which
incorporates various technologies for optimum circuit
design, high voltage isolation and very high
reliability.
Variants are provided to meet German (-1) and UK
(-3) line impedance (see section on Line
Impedances), as well as a 600Ω variants (-2).
Applications
Interface to Central Office for:
• DAA
•
•
•
•
Modem
FAX
Answering Machine
Terminal Equipment
Isolation Barrier
Power
Supply
Opto-
Isolation
Opto-
Isolation
TXIN
TF
RLS
Input
Buffer
Opto-
Isolation
Ring & Loop
Buffer
USER CONNECTIONS
Audio Input
Buffer
Opto-
Isolation
VDD
AGND
TIP
RING
Active
Termination
Logic Input
Buffer
Audio
Buffer
Transhybrid
Loss
Cancellation
Circuit
LC
VR
Audio
Buffer
VX
RVLC
NETWORK CONNECTIONS
Figure 1 - Functional Block Diagram
2-21
MITEL [ MITEL NETWORKS CORPORATION ]
