Protection of inductive load switching transistors from inductive surge created overvoltage conditions

摘要

An arrangement for protecting inductive load switching transistors during overvoltage conditions is disclosed. The arrangement comprises a Zener diode coupled between the collector and base of the switching transistor, where the Zener diode will break down during inductive load- created overvoltage conditions and turn on the transistor. A major portion of the surge current will then flow through the activated transistor. In a particular integrated circuit realization of the arrangement, the Zener diode is formed in the same semiconductor area as the transistor by extending a portion of the base diffusion region downward to contact the buried collector region.