Patent ID: 8134348

Claim:
A DC-DC converter comprising: an error amplifying circuit to output an error signal by amplifying a difference between a reference voltage and a feedback voltage for an output voltage generated by switching an output transistor between on and off; a triangular wave generation circuit to generate a triangular wave; a PWM comparison circuit to compare the triangular wave with the error signal and output a duty control signal having a duty ratio based on the comparison; a pulse width control circuit to control a pulse width of the duty control signal output from the PWM comparison circuit; and a drive circuit to drive the output transistor according to a signal output from the pulse width control circuit, wherein the pulse width control circuit comprises: a first circuit to reduce the pulse width of the duty control signal output from the PWM comparison circuit by a predetermined amount; a second circuit to increase the pulse width of the duty control signal output from the PWM comparison circuit by a predetermined amount; and a selector to select and output one of signals output from the first circuit and the second circuit, the selector being controlled based on the output voltage and an input voltage.