Patent ID: 6594131
Filing Date: 2003-07-15
Classification: H03K

Abstract:
An over current protection circuit of a semiconductor switching device comprising:a gate voltage controlled type semiconductor switching device having a main current element with a first current output terminal and a detection current element with a second current output terminal; a resistor connected between the first current output terminal and the second current output terminal, for detecting a voltage; and a control circuit connected to a gate terminal of the semiconductor switching device and the resistor, for decreasing a gate voltage applied to the semiconductor switching device when the voltage detected by the resistor exceeds a first set value, and cutting off the gate voltage applied to the semiconductor switching device when the gate voltage reaches a predetermined voltage set for a predetermined over current cut-off value, the control circuit comprising a bipolar transistor one output terminal of which is connected to the first current output terminal, a diode connected between the other output terminal of the bipolar transistor and the gate terminal of the semiconductor switching device, and a capacitor connected between a base terminal of the bipolar transistor and said other output terminal of the bipolar transistor.