Patent ID: 8143795

Claim:
A circuit arrangement for starting a discharge lamp, comprising: a first and a second input terminal for connecting an input voltage; an inverter, which has an input and an output, the input being coupled to the first and the second input terminal and the output being coupled to a first and a second output terminal for connecting the discharge lamp; a resonant circuit including a resonant inductor, which is coupled between the output of the inverter and the first output terminal; a regulating apparatus for regulating the frequency of the signal provided at the inverter output; and a current measuring apparatus, which is arranged so as to measure a current which is correlated with the current in the resonant circuit, wherein the regulating apparatus is adapted to regulate the frequency at the output of the inverter as a function of the measured current, and wherein the regulating apparatus comprises: a first memory apparatus for storing a value which has been correlated with a maximum (I max ) of the current in the resonant circuit; a comparison apparatus for comparing a value (I act (f)), which has been correlated with the current in the resonant circuit and which results given the instantaneous frequency of the signal at the output of the inverter, with the maximum (I max ) stored in the first memory apparatus; and a writing apparatus for the case in which the value (I act (f)), which has been correlated with the current in the resonant circuit and which results given the instantaneous frequency of the signal at the output of the inverter, is greater than the previously input maximum (I max ), to imput this value (I act (f)) into the first memory apparatus.