Patent ID: 7751209

Claim:
A switching power supply equipment comprising: an error amplification circuit amplifying a difference voltage between an output voltage of the switching power supply equipment and a predetermined voltage, the error amplification circuit outputting an amplified output; a switching control circuit coupled to the error amplification circuit, wherein operation of a switching element coupled to the switching control circuit is controlled by the switching control circuit based on the output of the error amplification circuit; a comparator which compares a reference voltage with a voltage of a feedback terminal of the switching control circuit to which the output of the error amplification circuit is input; a protection circuit coupled to an output of the comparator, wherein the protection circuit functions at a time of abnormality of the output voltage of the switching power supply equipment based on the output of the comparator; a delay circuit for delaying operation of the protection circuit, wherein the delay circuit is connected to the feedback terminal and comprises a resistor and a capacitor in series, and wherein the feedback terminal is connected to a first voltage source through a first charging resistor; and a diode between the feedback terminal and the first charging resistor wherein a cathode of the diode is connected to the feedback terminal and the feedback terminal is connected to a second voltage source through a first charging current source or a second charging resistor.