| 摘要 |
PURPOSE:To prevent a malfunction at the time of activating, etc., by providing a protecting circuit to clamp a voltage rising between a gate and a source when all switching elements are off. CONSTITUTION:When all switching elements 2, 4, 6 and 8 are off at the time of activating, etc., a voltage with a large dv/dt is impressed to a FET Q, which is a voltage driving element, between the drain and source, and when the voltage is about to be generated through a distribution capacity between a gate G and a source S, transistors Q0 and Q1 to be Darlington-connected of a protecting circuit 5 are turned on, the voltage rising is clamped, and the malfunction is prevented. In an action condition, the series circuit of the transistors Q0 and Q1 and a diode D1 is always in an off-condition, the lowering of an impedance between the gate G and source S is not caused, and thereby, the increase of a driving power is unnecessary. Thus, without damaging the drive of the voltage drive element by a small power, the malfunction at the time of activating, etc., can be prevented. |
