Ringing Generator Sub-Assembly; Microprocessor Operation - GE JungleMUX 86445-31 Technical Practice And Installation Manual

Ringing Generator Sub-Assembly

The 86445-03 is equipped with a sub-assembly board, which provides a DC-to-
DC converter and square wave ringing generator.
The sub-assembly board is connected to the main assembly board via P3 and
J3.
The DC-to-DC converter U1 is a current mode switch operating in a buck-boost
configuration. The output voltage (-28V or -56V) is kept constant by controlling
the transfer of energy from the power source Vin(+5V) to the load.
When the switch is closed, current is drawn from the power source and stored
energy is kept in inductor L1. When the switch opens, energy is transferred from
the inductor to the output capacitor C7.
Duty cycle for the switch is controlled by the voltage divider reference of R5 and
R7 for -28V and R5 and R6//R7 for -56V. Q2 acts as a switch for selecting -28V
or -56V depending on the gate level controlled by the micro controller U1.

Microprocessor Operation

U1, 68HC11V1 micro-controller, is the CPU for the 86445-31 2W FXS unit and
operates in expanded mode. The CPU provides the following functions:
Communication with the user through the Craft Interface port
•
Controls the front panel LEDs and processes the activation of the ACK
•
push button switch
Monitors the unit temperature sensor LM34(U9) and voltage converter
•
Controls configuration of PLGA U5 including battery voltage control
•
depending on user's setting
Communication of alarm Information to the JIF/JIF-Share unit for the
•
Network Management System
Crystal Y1 provides the 8.0 MHz clock to the microprocessor.
Copyright  GE Multilin Inc. 2002
342-86400-445PS
Issue 4.0
October 2006
Page 20