| 摘要 |
PURPOSE:To prevent an element from damaging by adding a monostable multivibrator operated by an overcurrent and temporarily stopping the operation of a DC/DC inverter with the output pulse of the multivibrator, thereby accelerating the responding speed. CONSTITUTION:Transistors Tr3, Tr4 are driven through a comparator 2 by the sawtooth wave of a sawtooth wave generator 8 and a difference between a load voltage and a reference voltage V2 to control main switching Tr1, Tr2. Thus, a voltage rectified through a transformer T2 and rectifiers D4, D5 and smoothed is supplied to a load 4. An overcurrent protecting circuit 9' applies a voltage to the comparator 2 to prevent the overcurrents of the Tr1, Tr2. In this case, the circuit 9' is formed of a comparator 10, a monostable multivibrator 11 and Tr5. When an overcurrent is flowed to the Tr1 and a voltage is generated at a resistor R12, the potential of the comparator 2 becomes the peak value or higher of the sawtooth wave voltage, AND circuits 6, 7 do not output pulses to stop an inverter and to softly start with a capacitor C8. |
