MH88520-1
Preliminary Information
TIP
IC
RING
RF1
IC
RF2
IC
VEE
LED
SHK
THRESH ADJ
VDD
AGND
VBAT
MUTE
JUNC
RRD
RGND
RRC
VRLY
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
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
IC
RING
RF1
IC
RF2
IC
V
EE
LED
SHK
THRESH ADJ
V
DD
AGND
V
BAT
MUTE
JUNC
RRD
RGND
RRC
VRLY
Description
Tip Lead.
Connects to the “Tip” lead (A-wire) of the telephone line.
Internal Connection.
Leave open circuit.
Ring Lead.
Connects to the “Ring” lead (B-wire) of the telephone line.
Ring Feed 1.
Connect to the Ring Relay contact. See Figure 5.
Internal Connection.
Leave open circuit.
Ring Feed 2.
Connect to normally closed contact of Ring Relay. See Figure 5.
Internal Connection.
Leave open circuit.
Negative Power Supply Voltage.
Normally -5V.
LED Drive (Output).
Drives an LED directly. A logic low indicates an off-hook condition.
Switch Hook Detect (Output).
A logic low indicates an off-hook and dial pulsing
condition. Open collector output with 10kΩ internal pull up to V
DD
.
Allows adjustment of SHK detection threshold as shown in Figure 6.
Positive Power Supply Voltage.
Normally +5V. This provides current for both internal
circuitry as well as the loop.
Analog Ground.
Supply and Battery Ground.
Battery Supply Voltage.
Normally -24V. This provides current to the loop.
MUTE (Input).
A logic low will mute signals coming from Tip-Ring to the JUNC pin.
JUNCTOR.
Ground (AGND) referenced transmit and receive speech path.
Ring Relay Drive (Output).
Connects to the ring relay coil. A logic low activates the
relay.
Relay Ground.
Return path for relay supply voltage. Normally connected to AGND.
Ring Relay Control (Input).
A logic high activates the Ring Relay Drive (RRD) outputs.
Relay Positive Supply voltage.
Normally +5V. Connects to the relay coil and the relay
supply voltage. An internal clamp diode from VRLY to GRND is provided.
2-64
MITEL [ MITEL NETWORKS CORPORATION ]
