Protection circuit for power components against overvoltages.

摘要

The protection circuit for a MOSFET power switching transistor includes a Zener diode (Z1) in series with a conventional diode (D1) connected between the drain and the gate of the MOSFET (20). The Zener diode conducts if the gate-drain voltage exceeds the break-over voltage of the Zener diode. If the Zener diode conducts the current is monitored (30) and the level used to control the gate drive circuit (22) of the MOSFET. As the current increases the MOSFET is driven to a low impedance conducting state to reduce its power dissipation.