Output voltage control circuit of power converter for light-load power saving

A method of light-load power saving for a power converter comprising:

• generating a first feedback signal through an optical coupler;
• generating a second feedback signal through a winding of a transformer;
• determining a light-load condition and generating a light-load signal in response to the first feedback signal and the second feedback signal;
• and
• generating a switching signal for switching the transformer and regulating an output voltage of the power converter in response to the first feedback signal and the second feedback signal;
• wherein the switching signal is generated in accordance with the first feedback signal when an output load is high;
• the switching signal is generated in accordance with the second feedback signal during the light-load condition.

A control circuit of a power converter for light-load power saving comprising:

• a first primary-side feedback circuit generating a first primary-side feedback signal through a winding of a transformer;
• a second primary-side feedback circuit generating a second primary-side feedback signal through the winding of the transformer;
• and
• a control circuit generating a switching signal for switching the transformer and regulating an output voltage of the power converter in response to the first primary-side feedback signal and the second primary-side feedback signal;
• wherein the control circuit comprises a threshold circuit determining a light-load condition and generating a light-load signal in response to the first primary-side feedback signal and the second primary-side feedback signal;
• the switching signal is generated in accordance with the first primary-side feedback signal when an output load is high;
• the switching signal is generated in accordance with the second primary-side feedback signal during the light-load condition, the output voltage at light-load is lower than the output voltage at heavy-load.

A light-load power saving method for a primary-side control power converter comprising:

• generating a first primary-side feedback signal and a second primary-side feedback signal through a winding of a transformer;
• determining a light-load condition and generating a light-load signal in response to the first primary-side feedback signal and the second primary-side feedback signal;
• and
• generating a switching signal for switching the transformer and regulating an output voltage of the power converter in response to the first primary-side feedback signal and the second primary-side feedback signal;
• wherein the switching signal is generated in accordance with the first primary-side feedback signal when an output load is high;
• the switching signal is generated in accordance with the second primary-side feedback signal during the light-load condition, the output voltage at light-load is lower than the output voltage at heavy-load.