| 摘要 |
PROBLEM TO BE SOLVED: To provide a power supply circuit that can suppress the occurrence of overshoot of an output voltage due to effects of a PWM signal as much as possible when stopping operation of a drive circuit if the output voltage becomes excessive. SOLUTION: The power supply circuit includes: a voltage adjustment circuit, which steps up an input voltage inputted from the pre-stage side in accordance with a received step-up signal so as to output it to the post-stage side as an output voltage; a PWM comparator, which generates a PWM signal according to the output voltage by input of a signal corresponding to the output voltage to a first terminal and input of an oscillation signal to a second terminal respectively; a drive circuit, into which the PWM signal is inputted and which generates a step-up signal in response to the ON-duty of the PWM signal so as to give the step-up signal to the voltage adjustment circuit; and a drive stop circuit that prevents the PWM signal, being the ON-duty, from being inputted to the drive circuit when the output voltage is in an overvoltage state. COPYRIGHT: (C)2009,JPO&INPIT
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