Power factor improving circuit and switching power supply

A power-factor improvement circuit configured to improve a power factor of an alternating-current power source by first inputting rectified voltage, which has been obtained by rectifying alternating-current power voltage of the alternating-current power source with a rectifying circuit, into a series circuit having a reactor and a switching element and secondly turning ON/OFF the switching element, and also configured to provide direct-current output voltage, the power-factor improvement circuit comprising:

• control means that inputs the output voltage from a voltage detecting terminal thereby turning ON/OFF the switching element on a basis of the output voltage;
• detection holding means that detects an abnormality when it occurs in the switching power device to stop an operation of the switching element and that outputs a holding signal while holding a stopped condition of the switching element;
• and
• abnormal operating signal outputting means for outputting an abnormal operating signal in the form of voltage more than a predetermined voltage to the voltage detecting terminal, based on the holding signal from the detection holding means.

A switching power device having a power-factor improvement circuit and a load circuit connected to the power-factor improvement circuit, the power-factor improvement circuit being configured to improve a power factor of an alternating-current power source by first inputting rectified voltage, which has been obtained by rectifying alternating-current power voltage of the alternating-current power source with a rectifying circuit, into a series circuit having a reactor and a switching element and secondly turning ON/OFF the switching element, and also configured to provide direct-current output voltage, wherein the power-factor improvement circuit comprises:

• control means that inputs the output voltage from a voltage detecting terminal thereby turning ON/OFF the switching element on a basis of the output voltage;
• detection holding means that detects an abnormality when it occurs in the switching power device to stop an operation of the switching element and that outputs a holding signal while holding a stopped condition of the switching element;
• abnormal operating signal outputting means for outputting an abnormal operating signal in the form of voltage more than a predetermined voltage to the voltage detecting terminal on the basis of the holding signal from the detection holding means;
• and
• abnormal signal detecting means configured to output an abnormal signal when detecting, on the basis of the abnormal operating signal from the abnormal operating signal outputting means, that the voltage detecting terminal has reached voltage more than the predetermined voltage.