Surge protective device having a surface collector region directly shorted to a base region

摘要

A surge protective device, which has a favorable surge- absorbing characteristic while avoiding increase in chip area and in process complexity, is disclosed. In a surge protective device having an ordinary planar bipolar transistor structure and having a voltage- regulation diode to absorb surge current by breakdown of a junction between an emitter region and base region thereof, a surface collector region thereof is shorted to the base region. Accordingly, when surge current is increased, a pn junction between a collector region and the base region is sufficiently forward biased, and thereby a backward transistor is formed. Surge current is sufficiently absorbed by the operation of the backward transistor.