In the switching power supply, a load state judgment circuit (25) judges the state of a load (20) according to a pulse signal VG to be used for ON/OFF control of a MOS transistor (8) as a switching element in a DC-DC converter (127). In order to reduce a p...

A converter directly connectable to the mains comprises a rectifier stage of the network voltage, a power factor correction pre-regulating circuit supplied with the rectified network voltage and producing a DC voltage of a certain nominal value, a DC-DC co...