Patent ID: 6922323
Filing Date: 2005-07-26
Classification: H04M

Abstract:
1. An overvoltage protection circuit operable to decouple a voltage source available at a Subscriber Line Interface Circuit (SLIC) from a subscriber loop line conductor when said voltage source is shorted to said conductor in a non-ringing condition, comprising: a fusing element coupled to said SLIC's terminal corresponding to said subscriber loop line conductor; a protection device disposed between said fusing element and a protected ground, wherein a first terminal of said protection device is coupled to said fusing element and a second terminal of said protection device is coupled to said protected ground; and a biasing circuit portion operable to bias a control gate terminal of said protection device such that when said voltage source is shorted to said subscriber loop line conductor, said protection device is biased into a low impedance conductive state for drawing a current between its first and second terminals, wherein said current is capable of opening said fuse element, thereby decoupling said voltage source from said subscriber loop line conductor.