Method for detection of non-zero-voltage switching operation of a ballast of fluorescent lamps, and ballast

A lamp ballast, comprising:

• a half-bridge circuit with a first and a second semiconductor switching element which are driven on the basis of first and second drive signals, and having an output at which a first voltage is available;
• a resonant circuit operably connected to the output of the half-bridge circuit,
• a voltage measurement circuit operably coupled to the output of the half-bridge circuit and operable to generate a voltage measurement signal which is dependent on the first voltage, the voltage measurement circuit including a capacitive voltage divider that is integrated in a semiconductor chip;
• and
• an evaluation circuit operably coupled to receive the voltage measurement signal, and configured to generate an evaluation signal based on a comparison of the voltage measurement signal with a reference value in each case before switching-on times of the first and second semiconductor switching elements, the evaluation circuit including a comparator configured to receive the voltage measurement signal, and a flip-flop connected to the output of the comparator.