| 摘要 |
PROBLEM TO BE SOLVED: To improve stability of operation for a semiconductor switching element, in a state in which a very large overcurrent flows continuously in the semiconductor switching element, because of short-circuit or the like of a load. SOLUTION: A gate drive circuit 2 outputs a control signal to a gate terminal G, which signal adjusts a collector current IC flowing from a collector terminal C of an IGBT1 to an emitter terminal E, on the basis of a current fed back from the emitter terminal E via e1 in figure. When it is detected by a sense current IS from a sense terminal S that the collector current IC exceeds a specified value, a current-limiting circuit 27 adjusts the control signal from the gate drive circuit 2, on the basis of the sense current IS, and restrains the collector current IC to be at most the prescribed value. By a changeover switch 9, the route of a feedback current is so switched that the current passes an inductance 8, and a voltage for restraining the change of increase and decrease of the collector current IC is generated in the inductance 8. A control signal, based on the feedback current which has passed the inductance 8, is outputted to the gate drive circuit 2.
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