Granted Patent B2

US 9,089,012 · App. 13/902,137 · Granted Jul 21, 2015

Abstract

Claims (24)

1. A system for regulating current in an LED lamp, the system comprising:

a control circuit in electrical communication with a secondary side of a transformer and electrically isolated from a primary side of a transformer, the control circuit comprising:

i. a current-sense circuit for sensing an LED current in an LED; and

ii. a current-control circuit for creating, based on the LED current, a digital control signal;

an isolation element for transmitting the digital control signal from the secondary side to the primary side without electrically bridging the primary and secondary sides; and

a switching circuit for controlling power delivered to the primary side based at least in part on the transmitted digital control signal.

2. The system of claim 1 , wherein the control circuit further comprises a dimming-signal decode circuit for decoding a received dimming signal, and wherein the current-control circuit creates the digital control signal further based on the received dimming signal.

3. The system of claim 2 , wherein the dimming signal is at least one of a phase-dimming signal, a 0-10 V dimming signal, or a DALI dimming signal.

4. The system of claim 2 , wherein the dimming signal comprises two or more of a phase-dimming signal, a 0-10 V dimming signal, and a DALI dimming signal, and wherein the dimming-signal decode circuit is configured to select one of the two or more signals in accordance with an order of precedence.

5. The system of claim 1 , wherein the current-sense circuit further senses a change in the LED current created by a phase-dimming controller, the current-control circuit creating the digital control signal based also on the sensed change.

6. The system of claim 1 , wherein the isolation element comprises an opto-isolator or a small-signal transformer.

7. The system of claim 1 , further comprising a startup circuit for starting the transformer in a discontinuous conduction mode.

8. The system of claim 1 , wherein the digital control signal comprises a PWM signal.

9. The system of claim 8 , wherein the switching circuit filters the PWM signal and drives a transistor gate with the filtered signal.

10. A method for regulating current in an LED lamp driven by a circuit including a primary side of a transformer electrically isolated from a secondary side of the transformer, the method comprising:

sensing an LED current in an LED on the secondary side of the circuit;

creating, using the control circuit, a digital control signal based on the LED current;

transmitting the digital control signal from the secondary side to the primary side without electrically bridging the primary and secondary sides; and

controlling power delivered to the primary side based at least in part on the transmitted digital control signal.

11. The method of claim 10 , wherein creating the digital control signal is further based on a received dimming signal.

12. The method of claim 11 , wherein the dimming signal is one or more of a phase-dimming signal, a 0-10 V dimming signal, or a DALI dimming signal.

13. The method of claim 11 , wherein the dimming signal comprises two or more of a phase-dimming signal, a 0-10 V dimming signal, and a DALI dimming signal, and further comprising selecting one of the two or more signals in accordance with an order of precedence.

14. The method of claim 10 , further comprising sensing a change in the LED current created by a phase-dimming controller, the digital control signal being based also on the sensed change.

15. The method of claim 10 , further comprising starting the transformer in a discontinuous conduction mode.

Assignments (10)