Patent ID: 8570019

Claim:
A switching power source apparatus comprising: a high-side switch connected to an input voltage; a ramp signal generator configured to generate a ramp signal in synchronization with a switching frequency of the high-side switch; an amplitude signal generator configured to generate an amplitude signal corresponding to an amplitude of the ramp signal; a superposing circuit configured to generate a second ramp signal having a positive inclination corresponding to the amplitude and frequency of the ramp signal and provide a superposed signal by superposing the second ramp signal on a first reference voltage; a controller configured to compare the superposed signal with a feedback signal corresponding to an output voltage, and if the feedback signal is lower than the superposed signal, control the ON timing of the high-side switch so that the high-side switch turns on, the controller being also configured to control the ON width of the high-side switch according to the amplitude signal, input voltage, and output voltage; and a sudden heavy load detector configured to detect if light load changes to heavy load according to the superposed signal and feedback signal, and if detects such a change, widen the ON width of the high-side switch.