Patent ID: 8755203
Filing Date: 2014-06-17
Classification: H02M

Abstract:
1. A switching power converter comprising: a transformer including a primary winding coupled to an input voltage and a secondary winding coupled to an output of the switching power converter; a switch coupled to the primary winding of the transformer, current through the primary winding being generated while the switch is turned on and not being generated while the switch is turned off; and a controller configured to generate a control signal to turn on or turn off the switch, the switch being turned on responsive to the control signal being in a first state and the switch being turned off responsive to the control signal being in a second state, wherein: the controller is further configured to determine a desired turn-on time of the switch in each switching cycle according to a pulse width modulation (PWM) or pulse frequency modulation (PFM) or a combination of PWM and PFM control mode employed by the switching power converter, independently of a transformer reset period or a resonant period of the voltage across the switch; the controller is further configured to calculate predicted timings at which a plurality of local minimums of a voltage across the switch are predicted to occur, the predicted timings of the local minimums being calculated prior to actual occurrences of the local minimums; and the controller generates in each switching cycle, while the controller is operating in the PWM or PFM control mode, the control signal in the first state to turn on the switch at an actual turn-on time corresponding to one of the plurality of predicted local minimums of the voltage across the switch that is predicted to occur subsequent to the desired turn-on time determined independently of the transformer reset period or the resonant period of the voltage across the switch according to the PWM or PFM or combination of PWM and PFM control mode during said each switching cycle.