| 摘要 |
PURPOSE:To protect other field effect transistors(FETs) connected in parallel with any of FETs by destroying the FET when an overvoltage takes place. CONSTITUTION:The voltage of a main capacitor 4 charged with a high voltage is fed to a load in a prescribed timing by a switching means 8 composed of FETs 9 of series and parallel connection. Then a series circuit composed a Zener diode 11 and a diode 12 is connected between the relevant gate and the drain of the FETs 9 whose gate is disconnected from the other gate in each stage of series connection and a resistor 13 is connected between the gate and a source. Thus, even when an overvoltage is applied to the FET 9, the prescribed FET 9 is conductive forcedly and destroyed according to the dynamic clamper characteristic. Thus, the further increase in the overvoltage is suppressed. |
