Patent ID: 8611109

Claim:
A flyback converter, comprising: input terminals and output terminals; a transformer with a first winding and a second winding, which are inductively coupled; a first switching element coupled in series with the first winding such that a first series circuit with the first switching element and the first winding is coupled between the input terminals; a rectifier arrangement coupled in series with the second winding such that a second series circuit with the rectifier arrangement and the second winding is coupled between the output terminals, the rectifier arrangement comprising a second switching element; and a control circuit configured in one drive cycle to switch on the first switching element for a first time period, after the first time period to switch on the second switching element for a second time period, to determine a third time period between an end of the second time period and a time at which the transformer assumes a predetermined transformer state, wherein: the control circuit determines the time at which the transformer assumes the predetermined transformer state by comparing a first voltage with a threshold, the first voltage comprising one of a voltage across the first switching element and a voltage across the second winding, the control circuit determines the threshold by determining a maximum value of the first voltage during the second and third time periods and weighting the determined maximum value, the control circuit is further configured to adapt the second time period to be applied in a subsequent drive cycle dependent on the second time period applied in the one drive cycle and dependent on the third time period determined in the one drive cycle, the second time period to be applied in the subsequent drive cycle is a sum of the second time period applied in the one drive cycle and an adjustment time period, and the adjustment time period is proportional to the third time period determined in the one drive cycle.