摘要 |
<p>An object of the present invention is to surely make protection from an overvoltage. When an overcurrent flows to an IGBT (1), a sink transistor (10) turns on and the IGBT (1) turns off accordingly. As the IGBT (1) turns off to cut off the overcurrent, a high surge voltage is applied to the IGBT (1). At this time, however, a clamp current flows trough a clamping circuit including a Zener diode (6), a diode (7) and a resistance (8) and part of it is divided to a transistor (Q11), so that a transistor (Q12) turns on and the sink transistor (10) turns off as the result. Accordingly, the clamp current increases a gate voltage of the IGBT (1). Hence, large part of the load current flows in the IGBT (1), and only a little flows to the clamping circuit. Accordingly, overheat of and damage by burning to the clamping circuit will not be caused even if both the overcurrent and overvoltage are applied. <IMAGE></p> |
申请人 |
MITSUBISHI DENKI K.K., TOKIO/TOKYO, JP |
发明人 |
GOURAB, MAJUMDAR, C/O MITSUBISHI DENKI K. K, NISHI-KU, FUKUOKA-SHI, FUKUOKA 819-01, JP;HIRAMOTO, TAKAHIRO, C/O MITSUBISHI DENKI K. K, NISHI-KU, FUKUOKA-SHI, FUKUOKA 819-01, JP;TANAKA, TAKESHI, C/O MITSUBISHI DENKI K. K., AMAGASAKI-SHI, HYOGO 661, JP |