Patent ID: 9419527
Filing Date: 2016-08-16
CPC Classification: H02M,Y02B

Claim Text:
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: responsive to a load level at the output of the switching power converter being less than a first load level but greater than a second load level, the second load level being less than the first load level, the controller is further configured to generate the control signal based on a first operation mode, during the first operation mode the switching power converter regulating a duty cycle of the control signal applied to the switch by performing one of: responsive to the load at the output of the switching power converter being less than the second load level but greater than a third load level, the third load level being less than the second load level, the controller is further configured to generate the control signal based on a second operation mode, during the second operation mode the switching power converter regulating the duty cycle of the control signal applied to the switch by keeping the conduction pulse width constant and varying the switching period; and wherein at a transition point between the first operation mode and the second operation mode, the controller is further configured to use a point during the first operation mode when the switch would have been turned on prior to transitioning to the second operation mode as a reference point to determine when to turn on the switch during the second operation mode.