Switching power supply, has evaluation device comprising voltage modification device coupled between capacitor and output of evaluation device, where modification device is formed to adjust voltage at capacitor to positive voltage levels

摘要

The supply has an evaluation device (14) comprising a diode (D1) and a capacitor (C2) coupled between an input (ES) of the evaluation device and a reference potential. The evaluation device provides a signal during a charging phase of a flyback converter at an output (A-s), where the signal is correlated with a charging state of the capacitor. The evaluation device comprises a voltage modification device (18) i.e. charge pump, coupled between the capacitor and the output of the evaluation device and formed to adjust voltage at the capacitor to positive voltage levels.