Patent ID: 7791913

Claim:
A secondary side switch-off timing adjusting method for a switching power conversion, comprising the steps of: detecting the falling edge of the voltage across a secondary side transistor according to a first reference voltage to generate a first reset signal; detecting the rising edge of the voltage across said secondary side transistor according to a second reference voltage to generate a first set signal; generating a secondary side discharging end signal from a first latch operation in response to said first reset signal and said first set signal; generating an off-predicting signal according to the cycle period of said secondary side discharging end signal; generating a second set signal and a turn-off signal from a blanking operation on said first reset signal; generating a second reset signal from a logic-or operation on said off-predicting signal and said turn-off signal; and generating a gating signal for driving said secondary side transistor from a second latch operation in response to said second reset signal and said second set signal.