A controller 7A for generating a drive signal PS for switching control
of
a switching element in a switching power supply, includes a duty ratio generator
10, 11 for detecting a duty ratio D of the drive signal PS for controlling
the switching element of the switching power supply, and generating a signal corresponding
to the duty ratio; a control signal generator 13, 14 for generating a control
signal CS on the basis of a difference between a target voltage VREF
in the switching power supply and an output voltage Vo detected in the
switching power supply; an operation unit 15 for generating a signal corresponding
to a product of the signal corresponding to the duty ratio, and the control signal
CS; and a drive signal generator 16, 17 for generating the drive signal
PS on the basis of the signal generated by the operation unit 15.
