MH88500
TIP
VA1
RING
RING FEED
IC
VC1
GND
V
B
LED
OFHK
THRESH ADJ
VA2
GND
VC2
MUTE
JUNCTOR
RD
RGND
RC
CD
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
Preliminary Information
Figure 2 - Pin Connections
Pin Description
Pin #
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
Name
TIP
V
A1
RING
RING FEED
IC
V
C1
GND
V
B
LED
OFHK
THRESH ADJ
V
A2
GND
V
C2
MUTE
JUNCTOR
RD
RGND
RC
CD
Description
Tip Lead.
Connects to the “Tip” lead (A-wire) of the telephone line.
Positive Line Feed Supply Voltage.
Normally connected to V
A2
.
Ring Lead.
Connects to the “Ring” lead (B-wire) of the telephone line.
Negative Line Feed Voltage and Ringing Input.
Normally connected to Ring Relay.
Internal Connection.
Leave open circuit. Use for testing only.
Sense Input.
Normally connected to negative line feed voltage supply.
Analog ground (0V).
Internally connected to pin 13.
Negative Analog Supply Voltage.
LED Drive Output.
Drives an LED directly. Off-Hook condition, logic low.
Logic Low Output.
Indicates closed loop condition (Off-Hook and dial pulsing).
Allows adjustment of OFHK detection threshold.
Positive Power Supply
Voltage. Normally connected to V
A1
.
Analog Ground (0V).
Internally connected to pin 7.
Loop Detector Voltage Supply.Connected
to negative line feed voltages supply.
Input mutes the incoming audio. Active low.
Receive/transmit audio speech path.
(referenced to 0V GND)
Relay Drive Output.
Open collector sinks current when RC high. Diode clamp
protected.
Ground for Relay Drive Circuit.
Ring Control Input.
Active high.
Clamping Diode.
Normally connected to relay positive voltage.
2-34
MITEL [ MITEL NETWORKS CORPORATION ]
