Raynet Corporation

David E Hurst

Mike Bushue

Steve Cartier

Craig A Lindahl

A voltage detection circuit, in conjunction with a power supply system for ringing voltage generation in a remote telecommunications unit, monitors the operating voltage level of the remote unit and, when an undervoltage condition is detected, causes a ringing reference-signal generator to collapse the reference (AC) sine wave into a fixed (DC) state and holds it in this state for a preselected time, thereby substantially reducing the ringing-signal current load and allowing the operating voltage level to restore. The features of the invention allow for continued processing of calls in progress and for incoming call completion during an undervoltage condition. The increased reliability and integrity of the power supply system allows for extended power supply feeder distance to the remote telecommunications unit.

Power supply system including ringing voltage reset under low input

A DC to DC switch mode power supply for a service subscriber interface unit of a fiber optic network includes a source of DC primary power, a main DC to DC switched mode power supply connected to the source of DC primary power and including switching circuitry and rectifier circuitry for supplying DC operating power to the service subscriber interface unit including central office battery power to at least one subscriber loop connected thereto, and a ringing voltage DC to AC switched mode generator connected to the source of DC primary power and including switching circuitry and synchronous rectification circuitry for generating ringing ringing voltage approximating a sine wave supplied as a reference to the synchronous rectification circuitry. A Johnson counter and resistor capacitor network is preferably employed to convert a reference ringing square wave into a sine wave.

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San Ramon, CA, United States of America

David E Hurst