Flyback power supply circuit and secondary side control circuit and control method thereof

• Main Authors: LI JUNQING, CHEN YUCHANG, YANG DAYONG, LUO LIDI, CHEN ZHAOQI, ZHONG HAOWEN, ZHANG WEIXU
• Format: Patent
• Language: Chinese; English
• Published: 16.04.2021
• Subjects: APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC,OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWERSUPPLY SYSTEMS; CONTROL OR REGULATION THEREOF; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUTPOWER; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER; ELECTRICITY; GENERATION

The invention relates to a flyback power supply circuit and a secondary side control circuit and a control method thereof. The flyback power supply circuit comprises a primary side control circuit used for controlling a primary side switch; a secondary side control circuit used for generating a synchronous rectification control signal to control the synchronous rectification switch, the synchronous rectification control signal has a synchronous rectification pulse and a zero-voltage switching pulse, and the synchronous rectification pulse controls the synchronous rectification switch to realize secondary side synchronous rectification; the secondary side control circuit samples and maintains the voltage of a first end of the synchronous rectification switch as a first voltage between a zero-voltage switching pulse ending time point and a next synchronous rectification pulse starting time point, and determines the time length of the zero-voltage switching pulse according to the first voltage so as to control t