| 摘要 |
<p>The present invention addresses the problem of providing a switching power supply device and a pulse width modulation circuit that are capable of operating stably in synchronization with a clock signal. In order to solve the abovementioned problem, a switching device (1A) and a pulse width modulation circuit (3A) are provided with: a square-wave voltage output means (8A) that switches a square-wave voltage (VPWM) to a level (L) when an integrated voltage (Vn) rises to an amount higher than an upper threshold voltage, and switches the voltage (VPWM) to a level (H) when the voltage (Vn) falls to an amount lower than a lower threshold voltage; and a clock means (6A) that outputs a first clock signal (VCL1) and a second clock signal (VCL2) which have a phase difference of 180°. The square-wave voltage output means (8A): (1) switches the voltage (VPWM) to the level (H) even when the voltage (Vn) has not reached the lower threshold voltage if the clock signal (VCL1) changes while the voltage (Vn) is falling; and (2) switches the voltage (VPWM) to the level (L) even when the voltage (Vn) has not reached the upper threshold voltage if the clock signal (VCL2) changes while the voltage (Vn) is rising.</p> |
