US 12,088,190 B2
Zero-voltage-switching control circuit, control method and switching power supply
Jian Deng, Hangzhou (CN); and Qiukai Huang, Hangzhou (CN)
Assigned to Silergy Semiconductor Technology (Hangzhou) LTD, Hangzhou (CN)
Filed by Silergy Semiconductor Technology (Hangzhou) LTD, Hangzhou (CN)
Filed on Apr. 7, 2023, as Appl. No. 18/131,992.
Application 18/131,992 is a continuation of application No. 17/085,046, filed on Oct. 30, 2020, granted, now 11,664,720.
Claims priority of application No. 201911089104.3 (CN), filed on Nov. 8, 2019.
Prior Publication US 2023/0246538 A1, Aug. 3, 2023
Int. Cl. H02M 3/335 (2006.01); H02M 1/08 (2006.01); H02M 1/00 (2006.01)
CPC H02M 1/083 (2013.01) [H02M 3/33592 (2013.01); H02M 1/0058 (2021.05); H02M 3/33515 (2013.01); H02M 3/33523 (2013.01); H02M 3/33576 (2013.01)] 22 Claims
OG exemplary drawing
 
1. A zero-voltage-switching control circuit for a switching power supply having a main power switch and a synchronous rectifier switch, wherein the zero-voltage-switching control circuit is configured to:
a) control the synchronous rectifier switch to be turned on for a first time period before the main power switch is turned on and after a current flowing through the synchronous rectifier switch is decreased to zero by detecting a switching cycle of the main power switch;
b) control the synchronous rectifier switch to be turned on for the first time period in a current switching cycle based on a time length of a last switching cycle of the main power switch; and
c) wherein a drain-source voltage of the main power switch is decreased when the main power switch is turned on, in order to reduce conduction loss.