LINE VOLTAGE DIMMABLE CONSTANT CURRENT LED DRIVER

• US 20100231136A1
• Filed: 08/25/2009
• Published: 09/16/2010
• Est. Priority Date: 03/13/2009
• Status: Active Grant

• Current Assignee: Led Specialists, Inc.
• Original Assignee: Led Specialists, Inc.
• Inventors: Sacks, Stephen, Reisenauer, William, Cannarili, Kevin
• Granted Patent: US 8,310,171 B2
• Time in Patent Office: Days
• US Class Current: 315/276
• CPC Class Codes: H05B 45/14 using electrical feedback from LEDs or from LED modules
• CPC Class Codes: H05B 45/3725 Switched mode power supply [SMPS]

Abstract

A programmable LED constant current driver circuit for driving LEDs at constant current and dimming the LEDs using standard, off-the-shelf dimmers is provided. The current driver circuit of the present disclosure includes a temperature compensation feature which controls the on time for the LEDs based on a measured temperature of the current driver and associated circuits. In another embodiment, the current driver circuit is designed to receive a 24 VAC input and drive one or more LEDs in a transformer-based system dimming system.

Claims

1. A current driver circuit for at least one LED comprising:

an input section adapted to receive a power waveform from a variable dimmer circuit;

a rectifier section for rectifying the input power waveform to a rectified voltage;

a current switching regulator adapted to provide a constant current to the at least one LED based on the rectified voltage; and

a controller adapted to determine a level of the rectified voltage, wherein if the level is below a first predetermined threshold, the current switching regulator is turned off and, if the level is a above a predetermined threshold, the current switching regulator is turned on.

2. The current driver circuit as in claim 1, further comprising a time delay module adapted to delay the turning on of the current switching regulator for a predetermined period of time.

3. The current driver circuit as in claim 2, further comprising a temperature sensor adapted to measure a temperature of the current driver circuit, wherein the predetermined period of time for delay is based on the measured temperature.

4. The current driver circuit as in claim 3, wherein the current switching regulator provides the constant current via a pulse width modulated (PWM) signal.

5. The current driver circuit as in claim 4, wherein an on time of the PWM signal is based on the measured temperature.

6. The current driver circuit as in claim 4, wherein an on time of the PWM signal is decreased when the measured temperature is above a predetermined temperature threshold.

7. The current driver circuit as in claim 3, wherein the rectifier section is a diode bridge.

8. A dimmable LED lighting system comprising:

a dimmer adapted for converting an input power waveform to a modified voltage signal based on a selectable setting;

a transformer adapted for reducing the modified voltage signal to predetermined voltage level; and

a constant current driver adapted for converting the reduced modified voltage signal to a constant current pulsed waveform, the duty cycle of the pulsed waveform being directly proportional to the selectable setting,

wherein the constant current driver include a current switching regulator in a single ended primary inductance converter (SEPIC) configuration.

9. The dimmable LED lighting system as in claim 8, wherein the transformer is a magnetic transformer.

10. The dimmable LED lighting system as in claim 9, further comprising a synthetic load adapted for providing an additional load to the dimmer.

11. The dimmable LED lighting system as in claim 8, wherein the transformer is an electronic transformer.

12. The dimmable LED lighting system as in claim 11, wherein the constant current driver further includes an input rectifier full wave bridge including at least one Schottky diode.

13. The dimmable LED lighting system as in claim 8, wherein the SEPIC configuration includes a coupled inductor adapted to reduce the inductance of the current driver.

14. The dimmable LED lighting system as in claim 8, further comprising a fault detection circuit adapted for detecting when the at least one LED is not present.

15. The dimmable LED lighting system as in claim 8, further comprising a switch coupled to the current switch regulator to select one of at least two output current levels.