SWITCHING POWER SOURCE DEVICE, SEMICONDUCTOR DEVICE, AND AC/DC CONVERTER

摘要

This switching power source device switches a switching element on and off using PWM control, thereby controlling the current flowing in a coil and obtaining a prescribed direct-current voltage. With this switching power source device, during a PWM ON period for turning the switching element on using the PWM control, switching of the switching element is enabled by a first pulse signal in a first period immediately after the start of the PWM ON period, the signal having a shorter cycle than the PWM cycle and the pulse width being gradually increased. Also, with this switching power source device, after the first period of the PWM ON period has elapsed, switching of the switching element is enabled by a PWM signal based on the PWM control. High-frequency noise can thus be reduced.