Patent ID: 8451576

Claim:
A method of protecting an electrical circuit from overcurrents, where the electrical circuit is connected between a tip conductor and a ring conductor, comprising the steps of: providing a first current sensing resistance for connection in series with the tip conductor; providing a second current sensing resistance for connection in series with the ring conductor; providing a first gated unidirectional thyristor having a gate terminal in a silicon substrate, a cathode terminal and an anode terminal connected between the tip conductor and a ground; providing a second gated unidirectional thyristor in the silicon substrate and electrically isolated from the first gated unidirectional thryristor by at least two substantially unfilled trenches in the silicon substrate and an isolation region sandwiched between the trenches, the second gated unidirectional thyristor having a gate terminal, a cathode terminal and an anode terminal connected between the ring conductor and the ground; sensing current passing through said first current sensing resistance to develop a corresponding voltage across said first resistance, where the current passing through said first resistance also passes through the tip conductor, and applying the voltage across said first resistance between the gate terminal and the cathode terminal of said first gated unidirectional thyristor; and sensing current passing through said second current sensing resistance to develop a corresponding voltage across said second resistance, where the current passing through said second resistance also passes through the ring conductor, and applying the voltage across said second resistance between the gate terminal and the cathode terminal of said second gated unidirectional thyristor.