| 摘要 |
PURPOSE: To hold a power transistor(TR) in a conductive state at the time of service interruption by connecting a diode between the drain of a 1st TR and the gate of a power TR and respectively connecting the gate and drain of a 2nd TR to the gates of the 1st TR and the power TR. CONSTITUTION: When a feeder 2 is interrupted (VA=0), a gate capacitor CGS in a power TR MP is charged with electricity and a TR M2 is in an interrupted state. Since voltage VA is lower than the gate voltage VGP of the TR MP, a diode D is reversely biased and the discharge of the gate capacitor CGS of the TR MO is suppressed. A current is leaked only from a TR M1 having an inherent diode DM1 and the diode D and the gate capacitor CGS of the TR MP is separated from a driver 3. Thereby when power supply voltage VA is dropped, the gate of the TR MP is automatically separated from all constitutional elements of a holding circuit 1 and the TR MR is held at a permanently conductive state. |
