Switching power supply apparatus

A switching power supply apparatus having a standby mode in which a burst operation is performed, comprising:

• a high-side first switching element and a low-side second switching element which are connected in series and across which a direct current (DC) input voltage is applied;
• a resonant circuit including a resonance reactor and a resonance capacitor connected in series, the resonant circuit being connected in parallel with one of the first switching element and the second switching element;
• and
• a controller configured to alternately on-off control the first switching element and the second switching element, the controller including:
• a peak power limiting circuit configured to monitor an input power and output a forced turn-off signal upon detecting that the input power exceeds a determined value,
• a charge and discharge circuit configured to generate a triangular wave voltage during a period of a soft start operation of the burst operation, and a period of a soft end operation of the burst operation, and
• an oscillation circuit configured to receive the forced turn-off signal from the peak power limiting circuit, and to receive the triangular wave voltage to generate an on-trigger signal and an off-trigger signal at a switching frequency corresponding to a value of the triangular wave voltage and output the off-trigger signal upon the receipt of the forced turn-off signal.