Patent ID: 8456143

Claim:
A DC-DC converter, comprising: an inductor for converting voltage; a driving switching element to control an electric current flowing through the inductor; a rectifying switching element to be turned on and off complementarily to the driving switching element; and a switching control circuit to generate control signals of the driving switching element and the rectifying switching element, wherein the switching control circuit includes: an error amplifier to output a voltage according to a potential difference between a feedback voltage from an output side and a reference voltage; a PWM control pulse generating circuit to receive an output of the error amplifier and generate PWM control pulses for controlling the driving switching element and the rectifying switching element by PWM control; a minimum on-time pulse generating circuit to generate a minimum on-time pulse having a pulse width corresponding to a minimum on-time of the driving switching element; and an off-timing delaying circuit to delay a switching timing of the rectifying switching element from its on-state to its off-state by the control signal of the rectifying switching element for a longer time as a load becomes lighter according to the output of the error amplifier at a time of a light load at which the PWM control pulses become narrower than a pulse width of the minimum on-time pulse.