A circuit for driving LEDs includes: —a transformer with a secondary winding for driving the LEDs and a primary winding, —a half-bridge arrangement fed with an input voltage and coupled to the transformer, —a resonant circuit between the half-bridge arrangement and the primary winding of the transformer, the resonant circuit having a given resonance frequency, and—a controller configured for switching the half-bridge arrangement with a switching frequency variable between first and second values. The second value is closer than the first value to the resonance frequency of the resonant circuit created between the half-bridge arrangement and the primary winding of the transformer. This boosts the voltage fed towards the LEDs via the transformer. The LEDs are preferably included in the form of series of LEDs connected to the secondary winding of the transformer via a rectifier placed outside the housing of the power-supply.