In an embodiment a direct current to direct current (DC-DC) converter includes a first switching circuit configured to switch a supply of an input voltage to an energy storage circuit configured to generate an output voltage, a driving circuit configured to drive the first switching circuit according to a comparison between the output voltage and a comparison voltage and a soft-start circuit configured to raise the comparison voltage from a start voltage to a target voltage during a soft-start phase of the DC-DC converter having a soft-start duration, wherein the soft-start circuit comprises a soft-start capacitor configured to provide the comparison voltage during the start phase, the soft-start capacitor having a soft-start capacitance, an auxiliary capacitor having an auxiliary capacitance, a second switching circuit configured to alternately charge and discharge the auxiliary capacitor with an auxiliary current according to a clock signal having a clock frequency and a charging circuit.