According to the present disclosure, a circuit arrangement for operating semiconductor light sources includes: a power input for inputting an AC input voltage, an output having a first output terminal, and a second output terminal, which is designed to connect a string of semiconductor light sources, a control input for controlling the operation of the circuit arrangement with a control signal, a rectifier circuit for converting the AC input voltage into a rectified voltage, a converter circuit for transforming the rectified voltage into a current which is suitable for the semiconductor light sources, a first switch arranged between the converter circuit and the output, for the switching of the current through the semiconductor light sources, and a first diode arranged between the first switch and the output, or between the converter circuit and the first switch.