US 12,273,039 B2
Resonant flyback power converter and switching control circuit and method thereof
Yu-Chang Chen, Nanto (TW); Ta-Yung Yang, Taoyuan (TW); Kun-Yu Lin, Hsinchu (TW); and Hsin-Yi Wu, Hsinchu (TW)
Assigned to RICHTEK TECHNOLOGY CORPORATION, Zhubei (TW)
Filed by Richtek Technology Corporation, Zhubei (TW)
Filed on Apr. 14, 2023, as Appl. No. 18/300,530.
Claims priority of provisional application 63/379,771, filed on Oct. 17, 2022.
Claims priority of provisional application 63/379,020, filed on Oct. 11, 2022.
Claims priority of provisional application 63/378,765, filed on Oct. 7, 2022.
Prior Publication US 2024/0120846 A1, Apr. 11, 2024
Int. Cl. H02M 3/335 (2006.01); H02M 1/00 (2006.01); H02M 1/32 (2007.01); H02M 3/00 (2006.01)
CPC H02M 3/33571 (2021.05) [H02M 1/0041 (2021.05); H02M 1/0058 (2021.05); H02M 1/32 (2013.01); H02M 3/01 (2021.05); H02M 3/33592 (2013.01); H02M 1/0009 (2021.05); H02M 1/0048 (2021.05); H02M 1/0054 (2021.05)] 18 Claims
OG exemplary drawing
 
1. A resonant flyback power converter, comprising:
a first transistor and a second transistor which are configured to form a half-bridge circuit;
a transformer and a resonant capacitor which are connected in series and are coupled to the half-bridge circuit; and
a switching control circuit configured to operably generate a first driving signal and a second driving signal to control the first transistor and the second transistor respectively for switching the transformer and the resonant capacitor to generate an output voltage;
wherein the turn-on of the first driving signal magnetizes the transformer, the on-time of the first driving signal is decreased in response to the decrease of an output load of the resonant flyback power converter;
wherein the second driving signal is configured to discharge the resonant capacitor, wherein during a DCM (discontinuous conduction mode) operation, the second driving signal includes a resonant pulse for demagnetizing the transformer and a ZVS (zero voltage switching) pulse for achieving ZVS of the first transistor;
wherein the resonant pulse is skipped when the output voltage is lower than a low-voltage threshold.