| 摘要 |
PURPOSE:To prevent the rush current at the application of power supply, by increasing gradually a slope of a sawtooth wave according to the time constant for increasing the pulse width of an output of a comparator resulting in increasing gradually the conduction angle of a thyristor from zero. CONSTITUTION:The slope of the sawtooth wave generated at a sawtooth wave generating circuit 16 is increased gradually according to the time constant of the time constant circuit 19 and the wave is inputted to a non-inverting terminal of a voltage comparator 15. An output of an error amplifier 14 amplifying a difference between a voltage dividing an output voltage and a reference voltage 13 is inputted to an inverting terminal of the voltage comparator 15. The width of the output pulse of the voltage comparator 15 is increased as the slope of the sawtooth wave is increased, and the conduction angle of the thyristor is increased gradually from zero just after the power supply application to be stable to a constant value. Thus, the DC voltage at the output is increased gradually from zero, allowing to prevent the rush current to a capacitor 7 for protecting the circuit. |
