Patent ID: 7075278

Claim:
A switching power supply controller comprising: control signal setting means for setting a control signal on the basis of an output voltage digitally converted in a switching power supply, and a target voltage; current estimating means for estimating an electric current flowing through an inductor of a smoothing circuit in the switching power supply, on the basis of a drive signal for controlling a switching element of the switching power supply, and for generating an estimated current signal; DC component removing means for extracting a DC component included in the estimated current signal estimated by the current estimating means and for removing the DC component from the estimated current signal; DC component resetting means for resetting the DC component extracted by the DC component removing means, every predetermined time; and comparing means for comparing the control signal set by the control signal setting means, with the estimated current signal after the removal of the DC component by the DC component removing means, and for detecting whether the estimated current signal after the removal of the DC component reaches the control signal.