Patent ID: 9680378
Date: 2017-06-13
CPC Classifications: H02M,Y02B

Claim:
1. A switching power-supply device that converts a first DC voltage supplied from an input power source into a second DC voltage and outputs the second DC voltage by turning on-and-off a switching element connected between the input power source and an inductor, comprising: a drive unit, which drives the switching element based on a drive signal; a control unit, which performs intermittent oscillation control of alternately repeating a period where the turning-on of the switching element by the drive unit is prohibited and a period where the turning-on of the switching element by the drive unit is permitted; and an error signal generator, which generates an error signal based on an error between a voltage corresponding to the second DC voltage and a reference voltage, wherein the control unit controls a timing, at which the turning-on of the switching element is permitted in the intermittent oscillation control, based on a signal indicating a comparison result between the error signal and a threshold value and an OFF time of the switching element based on the drive signal, wherein in a case where the OFF time of the switching element based on the drive signal becomes a predetermined time threshold value in the intermittent oscillation control, the control unit permits the turning-on of the switching element, and wherein the predetermined time threshold value is set to a value at which a lowest switching frequency of the switching element in the intermittent oscillation control is higher than a predetermined lower frequency limit.