Patent ID: 7936152

Claim:
A switching power source comprising: a rectification circuit configured to produce a pulsating output by full-wave-rectifying an AC power source voltage; a chopper circuit, including an inductor connected to the rectification circuit, a switching element that shunts when switched on, a current flowing through the inductor, and a capacitor configured to produce a DC output by smoothing a current supplied from the inductor; a first signal generator configured to generate a first threshold value signal that is in phase with, and similar in waveform to, an input voltage of the chopper circuit, and is proportional in amplitude to an error of an output voltage of the chopper circuit; a second signal generator configured to generate a second threshold value signal approximately proportional in amplitude to the first threshold value signal; a current detector configured to detect the current flowing through the inductor; and a switching control configured to turn off the switching element when a current detection value of the current detector reaches a level of the first threshold value signal, and to turn on the switching element when the current detection value becomes lower than a level of the second threshold value signal.