The present invention relates to a resonant step-down DC-DC power converter which comprises a primary side circuit and a
secondary side circuit coupled through a
galvanic isolation barrier. The primary side circuit comprises a positive and a negative input terminal for
receipt of an input
voltage and an input
capacitor coupled between the positive and negative input terminals and the
secondary side circuit comprises an output
capacitor chargeable to a converter output
voltage between a first positive
electrode and a second negative
electrode. A resonant network is con-figured for alternatingly being charged from the input
voltage and discharged to the output
capacitor through the
galvanic isolation barrier by a
semiconductor switch arrangement in accordance with a switch
control signal to produce the converter output voltage. The resonant step-down DC-DC power converter comprises an electrical short-circuit connection across the
galvanic isolation barrier connecting, in a first case, the second negative
electrode of the output capacitor to the positive input terminal of the primary side circuit or, in a second case, connecting the second positive electrode of the output capacitor to the negative input terminal of the primary side circuit thereby establishing in both the first and second cases a series
coupling of the output capacitor and the input capacitor. A load connection is established, in the first case, between the first positive electrode of the output capacitor and the positive input terminal or, in the second case, between the second negative electrode of the output capacitor and the negative input terminal.