Patent ID: 6295214
Filing Date: 2001-09-25
Classification: H02M

Abstract:
A switching power supply unit, which rectifies and smoothes an AC current and an AC voltage from an on-off switching operation of a main switching element to output a DC current and a DC voltage, comprising an output current detection circuit including a current detection resistor disposed in an intermittent-current flowing path through which a current intermittently flows in sync with the on-off switching operation of the main switching element, a synchronous rectifying element comprising a switching element for rectifying a current flowing through the current detection resistor, and a capacitor for charging the current rectified by the synchronous rectifying element, wherein the current flowing through the current detection resistor is charged in the capacitor by a rectifying operation of the synchronous rectifying element, and a charging voltage of the capacitor is provided as a voltage corresponding to the output current of the switching power supply unit.