Active clamp protection circuit for power semiconductor device for high frequency switching

摘要

A protection circuit for a power transistor includes a first transistor connected in parallel with the power transistor and having a control terminal connected to a first power supply voltage through a first resistive element; and a first set of diodes connected between a first terminal and a control terminal of the first transistor. In operation, the voltage at the first terminal of the first transistor is clamped to a clamp voltage and the first transistor is turned on to conduct current in a forward conduction mode when an over-voltage condition occurs at a first terminal of the power transistor.

主权项

1. A protection circuit for a power transistor, the power transistor including a first terminal configured to drive a load, a second terminal coupled to a first power supply voltage, and a control terminal configured to receive a control signal, the protection circuit comprising:
a first transistor having a first terminal coupled to the first terminal of the power transistor, a second terminal coupled to the first power supply voltage, and a control terminal coupled to the first power supply voltage through a first resistive element, wherein the control terminal of the first transistor does not receive the control signal driving the power transistor; and a first plurality of diodes connected between the first terminal and the control terminal of the first transistor, wherein a voltage between the first terminal and the control terminal of the first transistor is clamped at a voltage sum of all diode voltages of the first plurality of diodes, the diode voltages comprising forward voltage or reverse voltage, wherein the first transistor is a dummy transistor and is normally turned off by having the control terminal connected to the first power supply voltage through the first resistive element, the first transistor is turned on to conduct current in a forward conduction mode in response to an over-voltage event occurring at the first terminal of the power transistor, the first transistor being turned on by a current flowing through the first plurality of diodes to the control terminal of the first transistor during the over-voltage event.