US 11,671,020 B2
Flyback converter, control circuit and control method thereof
Xiangdong Yang, Hangzhou (CN); Xiaoru Xu, Hangzhou (CN); Yongjiang Bai, Hangzhou (CN); and Zhiliang Hu, Hangzhou (CN)
Assigned to Silergy Semiconductor Technology (Hangzhou) LTD, Hangzhou (CN)
Filed by Silergy Semiconductor Technology (Hangzhou) LTD, Hangzhou (CN)
Filed on Apr. 26, 2021, as Appl. No. 17/239,831.
Application 17/239,831 is a continuation of application No. 16/567,051, filed on Sep. 11, 2019, granted, now 11,018,590.
Claims priority of application No. 201811086983.X (CN), filed on Sep. 18, 2018.
Prior Publication US 2021/0242784 A1, Aug. 5, 2021
Int. Cl. H02M 3/335 (2006.01)
CPC H02M 3/33523 (2013.01) [H02M 3/33515 (2013.01); H02M 3/33592 (2013.01)] 19 Claims
OG exemplary drawing
 
1. A control circuit for a flyback converter, the control circuit comprising:
a) a detection circuit configured to generate a sampling voltage representing a drain-source voltage of a main switch in the flyback converter when the main switch is turned on, and to generate a detection signal in accordance with the sampling voltage; and
b) an auxiliary switch control circuit configured to adjust a conduction time of an auxiliary switch in the flyback converter according to a reference voltage signal, in order to achieve zero-voltage switching of the main switch, wherein the reference voltage signal is adjusted in accordance with the detection signal such that the conduction time is reduced when the detection signal is active and increased when the detection signal is inactive.