DC-DC converter circuit to supply discharge lamp, e.g. for vehicle, uses minimization of interval between secondary current falling to zero and primary current circulating to maximize switching frequency

摘要

The chopper circuit has a transformer (10) with a switch (11) in its primary. The time interval between the moment where the transformer secondary current (10s) reaches zero and the moment where the transformer primary current (10p) starts to circulate is detected, and the switching frequency is adapted to reduce this interval.