| 摘要 |
When bypassing a high voltage surge by externally installing a diode between a collector and a gate and protecting a circuit by turning on an IGBT, it is difficult to select a withstand voltage of the diode, because the withstand voltage of the IGBT must be higher with a certain margin. In the present invention, regions of an inverse conductivity type are formed in a high resistivity layer of an IGBT as in base region, and a transistor is formed together with a collector layer of an inverse conductivity type, which is connected between the collectors of an IGBT to be utilized as a clamping transistor. The breakdown voltage of this transistor is made lower than the breakdown voltage of a bipolar transistor of the IGBT main body. Then when the transistor breaks down, the gate-emitter capacity of the IGBT is charged and the IGBT is turned on, thus absorbing the high energy produced by an abnormal voltage into the chip and increasing the withstand capacity.
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