Patent ID: 8624637

Claim:
A circuit for controlling the switching operation of a transistor having a control electrode, a first load terminal operably coupled to a first supply potential, a second load terminal operably coupled to an electric load for providing an output voltage and for supplying a load current to the load and a current path between the first and second load terminals, the circuit comprising: a driver circuit operably coupled to the control electrode and configured to charge and discharge the control electrode to switch the transistor on and off, respectively, in accordance with a control signal, the charging and discharging of the control electrode being such that corresponding transitions in the load current and the output voltage are smooth with a defined slope; a controllable switch coupled to the control electrode such that, when the switch closes, the control electrode is quickly discharged via the switch thus switching off the transistor with a slope steeper than the defined slope; and a control logic circuit configured to close the controllable switch for switching off the transistor when at least one of the following conditions holds true: (1) the output voltage becomes negative; (2) a total power dissipated in the transistor is higher than a given power limit; (3) the load current is higher than a first current threshold; (4) the load current has a positive temperature coefficient and the load current exceeds a second current threshold; and/or (5) the load current has a positive temperature coefficient and a voltage drop across the load current path of the transistor exceeds a voltage threshold.