Protective device electronic semiconductor component

Abstract

To protect a discrete electronic component such as a bipolar transistor or a field-effect transistor against destructive current surges, one or two ancillary transistors are formed in the same semiconductor body which has a major portion thereof overlain by an output electrode constituting a variable-voltage terminal connected to a load. This major portion, acting as the collector of the bipolar transistor (or of two such transistors in a Darlington configuration) or as the drain of the FET to be protected, also forms the collector of each ancillary transistor whose emitter is grounded through a constant-current generator or through a resistor. The emitter potential of a single ancillary transistor, or the potential difference of the emitters of two such transistors of mutually different current densities, varies as a function of temperature and is compared with a reference voltage to apply, in the event of an overload, an inhibiting signal to a driver stage for blocking or limiting the conduction of the protected component.