A power converter (1) comprises a voltage level increasing circuit (3) which receives a DC-input voltage (VIN) between first and second power converter inputs (IN1, IN2), and which has an output (O1; O2, O3) to supply an adapted input voltage having either a higher level than the input voltage (VIN) or a polarity opposite to the input voltage (VIN). A down-converter (2) has first and second down-converter inputs (IN3, IN4), a control switch (S1) with a main current path arranged between a first node (N1) and the first down­converter input (IN3), an inductor (L) arranged between the first node (N1) and a load (LO), and a sync switch (S2) arranged between the first node (N1) and the second down-converter input (IN4). A controller (4) controls the control switch (S1), and switches (S3, S4; S3, S4, S5, S6, S7, S8) of the voltage level increasing circuit (3) for either coupling the input voltage (VIN) or the adapted input voltage to the first node (N1) or to the first or second down­converter inputs (IN3, IN4).