An electronic device for powering a fluorescent lamp (16) starting from a sinusoidal alternating voltage comprises a whole-bridge rectifier (12) which rectifies the alternating voltage, a circuit (13) for processing the rectified voltage connected in parallel to the output of the rectifier (12) and a half-bridge inverter (14) with an output (D) for high frequency powering of the lamp (16). The processing circuit has a direct voltage output (A-C) at the ends of a bulk capacitor (CB) connected in parallel to the output of the rectifier (12) through a first diode (DP). A resonant network (17) to which is connected the lamp (16) is connected between the output (D) of the half-bridge inverter (14) and an intermediate point (B) of a series of two capacitors (CP1,CP2) connected in parallel to the output of the rectifier (12). The circuit allows obtaining with simplicity a power factor near unity and a limited lamp current crest factor.