LED control system
First Claim
Patent Images
1. A power factor LED control system comprising:
- a plurality of series coupled LEDs coupled to receive an LED current between an input and a first common return;
an error amplifier coupled to form an error signal that is representative of the LED current; and
a PWM controller coupled to receive a signal that is representative of the LED current and control the LED current to a substantially constant value wherein the PWM controller is coupled between the first common return and a second common return to receive an operating voltage for the PWM controller wherein the PWM controller does not sense a waveshape of an AC input voltage received by the power factor LED control system.
5 Assignments
0 Petitions
Accused Products
Abstract
In one embodiment, an LED system is controlled to have a substantially unity power factor.
62 Citations
15 Claims
-
1. A power factor LED control system comprising:
-
a plurality of series coupled LEDs coupled to receive an LED current between an input and a first common return; an error amplifier coupled to form an error signal that is representative of the LED current; and a PWM controller coupled to receive a signal that is representative of the LED current and control the LED current to a substantially constant value wherein the PWM controller is coupled between the first common return and a second common return to receive an operating voltage for the PWM controller wherein the PWM controller does not sense a waveshape of an AC input voltage received by the power factor LED control system. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
-
-
10. A power factor LED control system comprising:
-
a plurality of series coupled LEDs referenced to a first common reference signal; an error amplifier coupled to provide an error signal that is representative of a current through the plurality of series coupled LEDs wherein the error amplifier is referenced to the first common reference signal; and a PWM controller operably coupled to receive a signal that is representative of the current through the plurality of series coupled LEDs and form a substantially dc voltage for operating the plurality of series coupled LEDs wherein the PWM controller is configured to operate at a substantially fixed frequency and a substantially constant duty cycle and wherein the PWM controller is referenced to a second common reference signal. - View Dependent Claims (11, 12, 13, 14, 15)
-
Specification