| 摘要 |
A quasi-resonant device for a switching power, a quasi-resonant system for a switching power, and a method for a quasi-resonant control of a switching power are provided. The quasi-resonant device includes: a degaussing time sampling module, configured to sample a degaussing time Tds of a secondary coil of the transformer according to a feedback signal output by the switching power after the switching tube is turned off; a valley sampling module, configured to sample a resonant valley signal of the quasi-resonant module according to the feedback signal; a time producing module, configured to produce a time T with a predetermined ratio D by processing the degaussing time Tds; and a logic processing module, configured to obtain a first valley signal after the time T, and the first valley signal works as a switching signal T' to turn on the switching tube. |
