Abstract: A power converter comprises an inductor (L) and a main switch (M1) having a main current path, the inductor (L) and the main current path are arranged in series to receive a DC-input voltage (VIN). A control circuit (CC) controls on-periods (Ton) and/or off-periods (Toff) of the main switch (M1) to stabilize an output voltage (VO) supplied to a load (LO). The control circuit (CC) further has an input (IN) to receive a measuring signal (MS) to protect the main switch (M1) against situations of overvoltage. A measuring circuit (MC) is coupled to a junction (J1) of the inductor (L) and the main current path to obtain the measuring signal (MS) which is indicative of a voltage across the main current path. Preferably, the measuring circuit (MC) comprises a peak-clamp.

Abstract: A DC-DC converter comprises a switch (S1) which periodically connects an inductor (L) to a DC-input voltage (Vi) during an on-period (Ton) of a period time (Tp), an operating frequency (fo) of the DC-DC converter is the inverse of the period time (Tp). An output (O1) of the DC-DC converter is coupled to the inductor (L) to supply an output voltage (Vo). A controller (CO) controls the operating frequency (fo) of the DC-DC converter to be substantially proportional to the output voltage (Vo) to obtain a substantially constant average duration of the on-period (Ton) as function of the output voltage (Vo).