| 摘要 |
PURPOSE:To eliminate the variation in a drooping characteristic operation point by adding the input voltage change to a voltage for controlling the overcurrent. CONSTITUTION:A DC rectified from an input AC is switched by a main switching transistor (Tr) 1, voltage-converted through a main transformer T1, rectified and power is supplied to a load RL. The voltage VO of a load RL is input to an operational amplifier 3, the conduction width of the Tr 1 is controlled through a pulse width controller 2 by an error from a reference voltage 5 to maintain the output voltage VO constant. In this case, the voltage in response to the input voltage change is formed as a DC voltage through a diode D5, a capacitor C2 and a resistor R2, and added to a voltage for deciding the drooping characteristic operation point of an operational amplifier 4. Thus, even if the input voltage rises and the voltage for deciding the drooping operation point of the amplifier 4 falls, the voltage proportional to the input voltage is applied to maintain the voltage for deciding the point constant. |
