| 摘要 |
PURPOSE:To increase the signal transmission speed without decrease in the service life of a photocoupler by providing a resistor, a buffer and a timer circuit in parallel with a resistor and a buffer connected in series with an input terminal of the photocoupler. CONSTITUTION:A drive signal U is inputted to a buffer 11 and a timer circuit 10 of a gate drive circuit 1, the timer circuit 10 outputs a high level for a preset time from a leading edge of the drive signal U and then outputs a low level and the output signal is inputted to a buffer 12. In this case, an input current IF to a photocoupler 15 is a sum of a current IF1 limited by a resistor 13 and a current IF2 limited by a resistor 14 for a preset time from a leading edge of the drive signal U and with the photocoupler 15 conductive, a current of IF=IF1+IF2 flows thereto and the current reaches the state of IF=IF1 in the steady-state of conduction. Thus, the operating speed is increased without reduction in the service life of the photocoupler. |
