| 摘要 |
PURPOSE:To improve the drive characteristic at the time of off by providing a circuit for applying a signal obtained in a secondary winding of a driving transformer in which a pulse width signal is impressed to a primary winding, to a gate of a MOSFET, and a resistance for applying the signal obtained in the secondary winding of the driving transformer, to a base of a transistor. CONSTITUTION:A MOSFET Q1 turns on and off a DC voltage Vin and applies it to a primary winding n1 of a transformer T, and to a primary winding N1 of a driving transformer T2, a pulse width signal is applied. A resistance R1 is connected in series between one terminal of a secondary winding N2 and a gate of the MOSFET Q1. A drive characteristic at the time when the MOSFET Q1 is on is determined by the resistance R1, and the drive characteristic at the time of off is determined by the resistance R1 and a collector-emitter voltage VCE of a transistor Q2. As a result, when the MOSFET Q1 is turned off, a reverse gate current flowing through the resistance R1 is amplified by the transistor Q2, an energy supply from the driving transformer T2 is a little and the MOSFET Q1 is turned off at a high speed. |
