MH88632B
Both Gains are programmable in the range -12dB to
+6dB. This wide range is capable of accommodating
most system loss plans. See Tables 3 and 4.
Preliminary Information
3. Tip Ground and Ring Ground Detect Outputs
(TG & RG)
The TG output provides a logic 0 when the Tip pin is
at ground (AGND) potential.
The RG output provides a logic 0 when the Ring pin
is at ground (AGND) potential.
Control Inputs
The MH88632B accepts control signals from the
system controller at the inputs Loop Relay Control
(LRC), Bias Relay Control (BRC) and Ground Ring
Relay Control (GRC). These energize the relay drive
outputs Loop Relay Drive (LRD), Bias Relay Drive
(BRD) and Ground Ring Relay Drive (GRD)
respectively. Each output is active low and has an
internal clamp diode to VRLY.
The intended use of each of these relay drivers is
shown in Figure 3. LRC is being used to add and
remove the Line Termination from across Tip and
Ring. BRC is used to connect Tip and Ring to -48V
via external bias resistors. GRC is controlling the
connection of Ring to AGND via an external bias
resistor.
If these Control Features and the Supervisory
Features are used as intended they can be used to
implement common Network Protocols such as
Loop-Start Signalling and Ground-Start Signalling.
Caller Line Identification
Caller Line Identification (CLI) provides the called
party with the calling party telephone number. The
Central Office will utilise the voice path of a regular
loop-start telephone line when the MH88632B is in
the on-hook state. The CLI information is typically a
Frequency Shift Keyed (FSK) data signal which is
output at TX.
Supervisory Features
Line Status Detection Outputs
The MH88632B supervisory circuitry provides the
signalling status outputs which are monitored by the
system controller. The supervisory circuitry is
capable of detecting: ringing voltage; forward and
reverse loop battery; forward and reverse loop
current; grounded tip lead; and grounded ring lead.
If these Supervisory Features and the Control
Features are used as indicated in Figure 3 they can
implement common Network Protocols such as
Loop-Start Signalling and Ground-Start Signalling.
1. Ringing Voltage Detect Output (RV)
The RV output provides a logic 0 when ringing
voltage is detected across Tip and Ring. This
detector includes a filter which ensures that the
output toggles at the ringing cadence and not at the
ringing frequency. Typically this output switches to a
logic 0 after 50ms of applied ringing voltage and
remains at a logic 0 for 50ms after ringing voltage is
removed.
2. Forward Loop and Reverse Loop Detect
Outputs (FL & RL)
The FL output provides a logic 0 when either forward
loop battery or forward loop current is detected, that
is the Ring pin voltage is negative with respect to Tip
pin voltage.
The RL output provides a logic 0 when either reverse
loop battery or reverse loop current is detected, that
is the Tip pin voltage is negative with respect to Ring
pin voltage.
Mechanical Information
See Figure 9 for mechanical specifications for the
MH88632B and Figure 10 for mechanical
specifications for the MH88632BT.
2-244
MITEL [ MITEL NETWORKS CORPORATION ]
