| 摘要 |
PURPOSE: To eliminate the need for an expensive and large power Zener diode by providing a means which has power MOSFET temperature control operation due to a semiconductor switch and suppresses voltage transition. CONSTITUTION: The semiconductor switch composed of a thyristor 2 is thermally connected with an MOSFET 1. When the MOSFET 1 is turned on and a load 3 is in ordinary state, the thyristor 2 is turned off. On the other hand, when a temperature becomes higher than the prescribed value because of the heat generated at the MOSFET 1, while the MOSFET 1 is turned on and the load 3 in short-circuited state, the thyristor 2 is turned on, a gate-source voltage is lowered, a drain-source current is blocked, and the MOSFET 1 is turned on and protected from damage. The voltage transition, which is generated by parasitic inductances 7 and 8 when the MOSFET 1 is turned on corresponding to the on of the thyristor 2, is suppressed by a means composed of a Zener diode 11, a rectifier diode 12, a thyristor 2, a resistor 10 and a Zener diode 5. |
