An illumination device (1) comprises: at least one low-power light source (50); a power input stage (20) suitable for receiving AC low voltage from an electronic transformer (ET); a power buffer stage (30) having an input (31) connected to the input stage output (29); a driver (40) for driving the light source and receiving electric power supply from the power buffer stage. The power input stage generates output current pulses for charging the power buffer stage at a relatively low frequency, and during each output current pulse, the power input stage draws input current, the input current always having a current magnitude higher than a minimum load requirement of the electronic transformer.