Patent attributes
A gate voltage detecting circuit 201 detects a gate voltage Vgs of a switching device 11, and when the gate voltage is less than a predetermined voltage that is set to be less than a threshold voltage of the switching device 11, outputs an H-level boost instruction signal. A voltage control circuit 103, when the boost instruction signal is at the L level, outputs a predetermined voltage V1 of a control power supply 102 as it is, and when the boost instruction signal is at the H level, outputs a voltage V2 obtained by boosting the predetermined voltage V1. The drive signal output circuit 104 amplifies a voltage of a PWM pulse output from a PWM pulse output circuit 111 to a voltage output from the voltage control circuit 103. Therefore, a drive signal from the drive signal output circuit 104 to the switching device 11 initially becomes the boosted voltage V2 when the PWM pulse goes to the H level, and then becomes the predetermined voltage V1 when the gate voltage Vgs of the switching device 11 increases to a predetermined voltage. Therefore, a switching loss of the switching device can be suppressed.
