A resonant step-down DC-DC power converter (100b, 100c) comprising: a primary side circuit (106b,106c) and a secondary side circuit (108b, 108c) coupled through a capacitor based galvanic isolation barrier (107b, 107c), the primary side circuit (106b, 106c) comprising a positive input terminal (102b, 102c) and a negative input terminal (101b, 101c) for receipt of an input voltage (V in) and an input capacitor (C in) coupled between the positive and negative input terminals, the secondary side circuit (108b, 108c) comprising an output capacitor (C out) chargeable to a converter output voltage (V out) between a first positive electrode and a second negative electrode (103b, 103c) of the output capacitor (C out), a resonant network configured for alternatingly being charged from the input voltage (V in) and discharged to the output capacitor (C out) through the galvanic isolation barrier (107b, 107c) by a semiconductor switch arrangement in accordance with a switch control signal to produce the converter output voltage, wherein the switch control signal has a frequency at or above 20 MHz, an electrical short-circuit connection (109b, 109c) across the galvanic isolation barrier (107b, 107c) connecting, in a first case, the second negative electrode (103b, 103c) of the output capacitor (C out) to the positive input terminal (102b, 102c) of the primary side circuit or, in a second case, connecting the first positive electrode of the output capacitor (C out) to the negative input terminal (101b, 101c) of the primary side circuit thereby establishing in both the first and second cases a series coupling of the output capacitor (C out) and the input capacitor (C in), a load connection, in the first case, between the first positive electrode (104b, 104c) of the output capacitor (C out) and the positive input terminal (101b, 101c) or, in the second case, between the second negative electrode (103b, 103c) of the output capacitor and the negative input terminal (101b, 101c). a primary side circuit (106b,106c) and a secondary side circuit (108b, 108c) coupled through a capacitor based galvanic isolation barrier (107b, 107c), the primary side circuit (106b, 106c) comprising a positive input terminal (102b, 102c) and a negative input terminal (101b, 101c) for receipt of an input voltage (V in) and an input capacitor (C in) coupled between the positive and negative input terminals, the secondary side circuit (108b, 108c) comprising an output capacitor (C out) chargeable to a converter output voltage (V out) between a first positive electrode and a second negative electrode (103b, 103c) of the output capacitor (C out), a resonant network configured for alternatingly being charged from the input voltage (V in) and discharged to the output capacitor (C out) through the galvanic isolation barrier (107b, 107c) by a semiconductor switch arrangement in accordance with a switch control signal to produce the converter output voltage, wherein the switch control signal has a frequency at or above 20 MHz, an electrical short-circuit connection (109b, 109c) across the galvanic isolation barrier (107b, 107c) connecting, in a first case, the second negative electrode (103b, 103c) of the output capacitor (C out) to the positive input terminal (102b, 102c) of the primary side circuit or, in a second case, connecting the first positive electrode of the output capacitor (C out) to the negative input terminal (101b, 101c) of the primary side circuit thereby establishing in both the first and second cases a series coupling of the output capacitor (C out) and the input capacitor (C in), a load connection, in the first case, between the first positive electrode (104b, 104c) of the output capacitor (C out) and the positive input terminal (101b, 101c) or, in the second case, between the second negative electrode (103b, 103c) of the output capacitor and the negative input terminal (101b, 101c).