System and method for driving LED
First Claim
1. 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.
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Accused Products
Abstract
A system drives one or plurality of LEDs regulating their brightness by controlling LEDs average current or voltage. The system includes a switching power converter and an integrated digital regulator with at least one of electrical, thermal and optical feedbacks. The regulator is constructed as a hysteretic peak current mode controller for continuous mode of operation of the power converter. For discontinuous mode of operation of the power converter a pulse averaging sliding mode control is being used. Average LED current is measured by integrating LED pulse current at off time and hysteretically adjusting on time of the power switch. Input battery is protected from discharging at abnormally low impedance of the output.
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Citations
22 Claims
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1. A system for driving one or plurality of LEDs, comprising:
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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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. An integrated controller to regulate a boost or a buck boost power converter for transferring electrical power from an energy source to LEDs in a form of controlled output current and providing said LEDs brightness regulation, said power converter being constructed as a switching discontinuous current mode converter, including an inductor, a rectifier, an output capacitor, an oscillator, 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, fully discharging said inductor, wherein said integrated controller regulating said dual phase cycle at a variable frequency and a constant off time by generating said on phase on time and receiving feedback signals from at least one of an electrical, thermal or optical sensors for sensing said LEDs performance and comprising:
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(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 of said LED'"'"'s 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 LEDs current signal to a set reference signal; and (v) a digital logic, sampling said comparator, resetting said integrator each cycle, measuring said last cycle time and incrementing said on time each cycle from cycle to cycle to turn on and off said primary switch to regulate said LED brightness. - View Dependent Claims (16, 17)
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18. An integrated controller to regulate a boost or a buck boost power converter for transferring electrical power from an energy source to LEDs in a form of controlled output current and providing said LEDs brightness regulation, a power converter being constructed as a switching discontinuous current mode converter, comprising an inductor, a rectifier, an output capacitor, an oscillator, 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, fully discharging said inductor, wherein said controller regulating said dual phase cycle at a variable frequency and a constant off time by generating said on phase on time and receiving feedback signals from at least one of an electrical, thermal or optical sensors for sensing said LEDs performance and comprising:
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(i) an LEDs current sensor; (ii) an R-C filter of said LEDs current; (iii) a comparator for comparing said filtered LED'"'"'s current signal to a set reference signal; and (iv) a digital logic, sampling said comparator, incrementing said on time each cycle from cycle to cycle to turn on and off said power switch to regulate said LEDs brightness. - View Dependent Claims (19, 20)
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21. A system for driving one or plurality of LEDs by transferring electrical power from an energy source to LEDs in a form of a controlled output voltage and providing said one or multiple strings of LEDs voltage 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;
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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 the said power converter and receiving feedback signal from said LEDs, comprising; (i) a LEDs voltage sensor; (ii) an integrator with a reset, coupled to said LED'"'"'s voltage sensor for generating an integrated said LED'"'"'s voltage signal over a cycle time; (iii) a divider, coupled to said integrator to divide an integrated signal by a last cycle time; (iv) a comparator for comparing said integrated and divided LEDs voltage 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 LED'"'"'s voltage; (vi) a D/A converter coupled to said digital logic to convert said control signal from digital to analog form; (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 said set point; and an oscillator, coupled to set digital logic.
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22. An integrated controller to regulate a boost or buck boost power converter for transferring electrical power from an energy source to LEDs in a form of a controlled output voltage and providing said LEDs brightness regulation, said power converter being constructed as a switching discontinuous current mode converter, including an inductor, a rectifier, an output capacitor, an oscillator, 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, fully discharging said inductor, wherein said controller regulating said dual phase cycle at a variable frequency and a constant off time by generating said on phase on time and receiving feedback signal from said LEDs and comprising:
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(i) an LEDs voltage sensor; (ii) an integrator with a reset, coupled to said LEDs voltage sensor for generating an integrated signal over a cycle time, based on said LED'"'"'s voltage signal; (iii) a divider, coupled to said integrator to divide integrated signal by a last cycle time; (iv) a comparator for comparing said integrated and divided LED'"'"'s voltage signal to a set reference signal; (v) a digital logic, sampling said comparator, resetting said integrator each cycle, measuring said last cycle time and incrementing said on time each cycle from cycle to cycle to turn on and off said primary switch to regulate the said LED'"'"'s voltage.
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Specification