| 摘要 |
PURPOSE:To make the stability of a load current good in a region in which the load current changes less with reference to a change in a load voltage. CONSTITUTION:The output of a comparator 42 in a PWM circuit is integrated by a resistor R1 and a capacitor C1, and a mean value is found. A voltage as the difference between its voltage and the output voltage of an amplifier circuit 3 is amplified by an amplifier 45, and an amplified voltage is input to the comparator 42. The output of the comparator 42 is integrated, a duty is converted into a voltage, the difference between the voltage and a voltage at a point B is found, and the device is operated so as to eliminate an error between the difference and a duty which is to be output originally. The output of the comparator 42 at this time is set to a duty of 100% when a voltage Vcc is input to the inverting input of the comparator 42, and it is set to a duty of 0% at 0V. When the difference between the voltage at the point B and that at a point D is amplified, the duty corresponding to the voltage at the point B is output precisely. |
