US 11,929,684 B2
Isolated power supply control circuits, isolated power supply and control method thereof
Yanmei Guo, Shanghai (CN); Zhen Zhu, Shanghai (CN); Yihui Chen, Shanghai (CN); Yuehui Li, Shanghai (CN); Xiaoru Gao, Shanghai (CN); Haifeng Miao, Shanghai (CN); and Hanfei Yang, Shanghai (CN)
Assigned to SHANGHAI BRIGHT POWER SEMICONDUCTOR CO., LTD., Shanghai (CN)
Filed by SHANGHAI BRIGHT POWER SEMICONDUCTOR CO., LTD., Shanghai (CN)
Filed on Dec. 14, 2021, as Appl. No. 17/550,659.
Claims priority of application No. 202011496777.3 (CN), filed on Dec. 17, 2020.
Prior Publication US 2022/0200466 A1, Jun. 23, 2022
Int. Cl. H02M 3/335 (2006.01); H02M 1/38 (2007.01)
CPC H02M 3/33592 (2013.01) [H02M 1/38 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A control circuit for an isolated power supply, the control circuit comprising:
a secondary-side control signal generator configured to receive a signal characterizing a voltage of a secondary-side winding in the isolated power supply and generate a secondary-side transistor switch control signal containing information about a turn-off instant of a secondary-side synchronous rectification transistor, the information about the turn-off instant of the secondary-side synchronous rectification transistor configured to turn off the secondary-side synchronous rectification transistor; and
a primary-side control signal generator configured to receive the secondary-side transistor switch control signal and a feedback signal of an output voltage of the isolated power supply and responsively generate a primary-side transistor switch control signal indicating a turn-on instant for a primary-side transistor switch,
wherein the primary-side control signal generator is configured to:
determine a second turn-on instant referring to the turn-off instant of the secondary-side synchronous rectification transistor according to the secondary-side transistor switch control signal;
determine a first turn-on instant referring to a supposed turn-on instant for the primary-side transistor switch according to the feedback signal of the output voltage of the isolated power supply; and
determine the turn-on instant for the primary-side transistor switch from the second turn-on instant or the first turn-on instant whichever is later, and responsively generates the primary-side transistor switch control signal.