| 摘要 |
PROBLEM TO BE SOLVED: To provide a driver for a switching element for the drive of a transformer which enables increase of the switching speed of a semiconductor switching element, the reduction of circuit scale, and the reduction of cost. SOLUTION: A switching control circuit 11 generates control signals SG3 and SG4 for gradually raising the duty ratio in the on/off action of both MOS transistors Q1 Q2, based on the soft control voltage V for temporarily changing from a soft start circuit 12. A voltage Vm for a negative bias is outputted from a capacitor C6, based on the AC voltage induced in a tertiary winding T3 of a transformer T. Drive circuits 13 and 14 turn on and turn off both the transistors Q1 and Q2, based on the control signals SG3 and SG4. Moreover, the drive circuits 13 and 14 apply the voltage Vm for bias to the gates of the transistors Q1 and Q2. when both the transistors Q1 and Q2 are turned off. |
