Patent ID: 8933639
Filing Date: 2015-01-13
Classification: H05B

Abstract:
1. A device for dimming a light source, said device comprising: a two-wire power supply line having interposed therein a switch for controlling transfer of said power supply towards said light source; a capacitance located downstream of said switch being traversed by a charge current as said switch is switched on, wherein said switch is opened and closed using a PWM dimming control signal; a driver for driving said light source, wherein said capacitance is arranged at the input of said driver and supplies power to the driver when said switch is open, whereby when said switch is made conductive again an inrush current is applied to said capacitance; a pre-charge stage interposed between said switch and said capacitance; said pre-charge stage being configured to limit said inrush charge current to a given value, wherein said pre-charge stage comprises: a sensor configured to sense the intensity of said charge current; a comparator configured to compare the intensity of said charge current as sensed by said sensor with said given value, a control switch interposed in said power supply line for driving by said comparator to interrupt said power supply to limit said charge current to said given value, so that in full operation, with a current leaving said pre-charge stage below said given value, said control switch remains stably closed enabling the normal transfer of power supply to said driver; and a buck converter to limit said inrush charge current to said given value.