Patent ID: 7583035

Claim:
A system for driving one or plurality of LEDs, comprising: an energy source; a power converter for transferring electrical power from said energy source to LEDs in a form of a controlled output current and providing said LEDs brightness regulation, said power converter being constructed as a switching converter, including an inductor, a rectifier, a power switch, operating in a dual phase cycle, having an on phase, when said power switch is closed, exciting said inductor by an input voltage, and an off phase when said power switch is open; a peak current sensor through said power switch; a regulator, controlling said dual phase cycle at a variable frequency and a constant off time, coupled to said power converter and receiving feedback signals from at least one of an electrical, thermal or optical sensor for sensing said LEDs performance and comprising: (i) an LEDs current sensor; (ii) an integrator with a reset, coupled to said LEDs current sensor for generating an integrated signal over said off phase of said cycle based on said LEDs current signal; (iii) a divider, coupled to said integrator to divide said integrated signal by a last cycle time; (iv) a comparator for comparing said integrated and divided LED's current signal to a reference signal; (v) a digital logic, sampling said comparator, resetting said integrator each cycle, measuring said last cycle time and generating a control signal to regulate said LEDs current; (vi) a D/A converter coupled to said digital logic to convert said control signal from digital to analog form; and (vii) a current peak comparator, connected to said peak current sensor to compare a peak current to a set point equal to said control signal and turning off said power switch, when said peak current in said power switch reaches a level of a set point; an oscillator, coupled to said digital logic; and a buffer to drive said power switch.