Method for actuating a switch in a free-running switched-mode power supply and control circuit for a switch in a free-running switched-mode power supply

摘要

The present invention relates to a method for the activation of a connected in series with a primary coil of a transformer in a free-running switched-mode power supply switch. The method comprises the provision of a modulation signal and providing a drive signal for the switch with a repeating sequence of pulses which at least one first switching pulse of a first pulse duration and at least one second switch-on pulse of a second pulse duration, wherein the pulse duration of at least one of the turn-on pulses within a predetermined value range by the control signal is modulated in accordance with the modulation signal.