Telephone subscriber loop overvoltage protection integrated circuit

Abstract From the Canadian patent

Abstract, An overvoltage protection circuit for communications systems is disclosed for protecting equipment from power crosses on electric utility lines. A timed latch circuit is used to activate a plurality of steering SCR's which crowbar the overvoltage. The utilization of a latch circuit to activate the steering arrangement, instead of the conventional technique of using actual overvoltage line current, allows smaller devices to be used, thus reducing both circuit size and circuit power dissipation,