Switching power conversion circuit

A switching power conversion circuit for converting an input voltage into an output voltage and issuing said output voltage to a load, said switching power conversion circuit comprising:

• a power circuit interconnected between an input terminal of said switching power conversion circuit and said load, and comprising a switching circuit and a first magnetic element, wherein said first magnetic element generates a magnetic flux change by alternately conducting or shutting off said switching circuit, so that said input voltage is converted into said output voltage by said power circuit;
• a feedback circuit having an input terminal connected to an output terminal of said power circuit, wherein said feedback circuit generates a feedback signal according to said output voltage;
• and
• a control circuit connected to said input terminal of said switching power conversion circuit, said switching circuit and an output terminal of said feedback circuit for controlling an on duration and an off duration of said switching circuit, thereby maintaining said output voltage at a rated voltage, wherein said off duration of said switching circuit is maintained at a constant interval under control of said control circuit, said on duration of said switching circuit is adjusted by said control circuit according to said feedback signal, and said on duration of said switching circuit is adjusted to be a specified interval smaller than a maximum on duration according to the magnitude of said input voltage.