A control device controls a switching circuit of a DC-DC converter. The switching circuit includes a half-bridge with at least first and second switches connected between an input voltage and a reference voltage. The converter comprises a transformer with a primary coupled with the center point of the half-bridge and a secondary coupled with a load. The control device comprises an error detector configured to determine an error signal representing a difference between a first signal representative of the voltage across the load and a first reference signal and a frequency controller configured to increase the switching frequency of the half-bridge when the error signal is kept below a second signal.