Circuit and method for protecting power components against forward overvoltages

摘要

A circuit protects a power transistor of the vertical MOS or IGTB-type during the off state against forward overvoltages. The protection circuit includes a first circuit for limiting the voltage across the transistor to a predetermined voltage, lower than the forward breakdown voltage of the power transistor, a circuit for detecting the quantity of energy dissipated in the transistor when the first circuit is enabled, and a second circuit for turning the transistor on at low impedance. The second circuit is enabled when the detection circuit has detected that the dissipated energy has exceeded a predetermined energy threshold.