Off line LED driver with integrated synthesized digital optical feedback
First Claim
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1. An off-line driver for powering a plurality of light emitting diodes, the off-line driver comprising:
- a power switch;
an AC bridge, a first terminal of the AC bridge coupled to a first terminal of the power switch;
a magnetic inductor, a first terminal of the magnetic inductor coupled to a second terminal of the AC bridge and couplable through an anode of a rectifier to the plurality of light emitting diodes, and a second terminal of the magnetic inductor couplable to a second terminal of the power switch;
the rectifier, a cathode of the rectifier couplable to the plurality of light emitting diodes; and
a regulator, comprising a voltage sense, an error amplifier, an integrator, a comparator, a latch, a switch driver, and a first current sense, the voltage sense couplable through the rectifier or the current sense to the plurality of light emitting diodes, the current sense coupled to the second terminal of the power switch and couplable to the plurality of light emitting diodes;
the error amplifier comprising a negative terminal coupled to the current sense and a positive terminal coupled to a combination of a customer set signal and an output signal of an optical model of the plurality of light emitting diodes;
the integrator coupled to a reset switch and having an input terminal coupled to the voltage sense, the integrator integrating only during an on-time of the power switch;
the comparator comprising a first terminal coupled to an output of the error amplifier and a second terminal coupled to an output of the integrator;
the latch comprising a set terminal coupled to an oscillator and a reset terminal coupled to an output of the comparator; and
the switch driver coupled to an output of the latch.
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Abstract
The present invention creates an LED driver in which all feedback signals are derived from a power stage media, and presents an isolated off-line LED driver with an accurate primary side controller only to power one or more LEDs. The present invention further provides an effective off-line LED driver comprising AC current shape controller with a minimum number of components. The present invention further provides a high quality luminous system based on LED drivers with the integrated synthesized optical feedback to compensate for imperfections of the LEDs as sources of light.
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Citations
41 Claims
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1. An off-line driver for powering a plurality of light emitting diodes, the off-line driver comprising:
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a power switch; an AC bridge, a first terminal of the AC bridge coupled to a first terminal of the power switch; a magnetic inductor, a first terminal of the magnetic inductor coupled to a second terminal of the AC bridge and couplable through an anode of a rectifier to the plurality of light emitting diodes, and a second terminal of the magnetic inductor couplable to a second terminal of the power switch; the rectifier, a cathode of the rectifier couplable to the plurality of light emitting diodes; and a regulator, comprising a voltage sense, an error amplifier, an integrator, a comparator, a latch, a switch driver, and a first current sense, the voltage sense couplable through the rectifier or the current sense to the plurality of light emitting diodes, the current sense coupled to the second terminal of the power switch and couplable to the plurality of light emitting diodes;
the error amplifier comprising a negative terminal coupled to the current sense and a positive terminal coupled to a combination of a customer set signal and an output signal of an optical model of the plurality of light emitting diodes;
the integrator coupled to a reset switch and having an input terminal coupled to the voltage sense, the integrator integrating only during an on-time of the power switch;
the comparator comprising a first terminal coupled to an output of the error amplifier and a second terminal coupled to an output of the integrator;
the latch comprising a set terminal coupled to an oscillator and a reset terminal coupled to an output of the comparator; and
the switch driver coupled to an output of the latch. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A method of providing power to a plurality of light emitting diodes (LEDs), comprising:
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(a) generating a DC voltage for application to the plurality of light emitting diodes; (b) amplifying an error between a light emitting diode current and a current reference value; (c) integrating the DC voltage to provide an integrated signal; and (d) identifying an on-time of a converter, wherein the on-time comprises a time period beginning when the integrating starts and ending when the integrated signal is equal to the amplified error. - View Dependent Claims (19, 20, 21, 22, 23, 24)
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25. An apparatus for powering a plurality of light emitting diodes, the apparatus comprising:
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an AC rectifier; a power switch coupled to the AC rectifier; a first diode couplable through a cathode terminal to the plurality of light emitting diodes; an inductive circuit element coupled to the AC rectifier and to a ground potential, the inductive circuit element further coupled to an anode terminal of the first diode; a voltage sensor couplable to the plurality of light emitting diodes; a first current sensor couplable to the plurality of light emitting diodes; and a regulator coupled to control the power switch in response to at least one operational parameter;
the regulator comprising an error amplifier to provide an error signal from a reference temperature level and a sensed temperature level of the plurality of light emitting diodes. - View Dependent Claims (26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41)
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Specification