Power supply system including ringing voltage reset under low input voltage conditions
First Claim
1. A power supply system for a telecommunications subscriber interface unit, comprising:
- reference signal means for converting an operating supply voltage into a ringing voltage signal shaped substantially according to a ringing reference signal; and
reference signal selection circuitry, which outputs either a reference AC sine wave as said ringing reference signal or a reference DC voltage as said ringing reference signal, depending on said operating supply voltage.
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Accused Products
Abstract
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.
48 Citations
19 Claims
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1. A power supply system for a telecommunications subscriber interface unit, comprising:
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reference signal means for converting an operating supply voltage into a ringing voltage signal shaped substantially according to a ringing reference signal; and reference signal selection circuitry, which outputs either a reference AC sine wave as said ringing reference signal or a reference DC voltage as said ringing reference signal, depending on said operating supply voltage. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A power supply system for generating on-demand ringing voltage signals in a remotely located subscriber interface unit of a fiber optic telecommunications network, comprising:
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means for generating a reference AC sine wave; means for generating a reference DC voltage; means for converting an operating supply voltage into an output voltage signal shaped substantially according to an input reference signal, said output voltage signal comprising an AC ringing voltage signal when said input reference signal is said reference AC sine wave and a steady-state DC offset voltage when said input reference signal is said reference DC voltage; and reference signal selection circuitry, said circuitry including means for providing said reference AC sine wave as said input reference signal and means for switching from said reference AC sine wave to said reference DC voltage as said input reference signal when said operating supply voltage drops below a predetermined level. - View Dependent Claims (11, 12, 13, 14, 15, 16)
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17. A method for maintaining minimum operating power in a telecommunications subscriber interface unit ("SIU"), the SIU including means for converting an operating supply voltage into a ringing voltage signal shaped according to a reference AC sine wave, comprising the steps of:
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monitoring the operating supply voltage; and switching the reference AC sine wave to a reference DC voltage for a preselected time interval when the operating supply voltage drops below a predetermined level. - View Dependent Claims (18, 19)
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Specification