Granted Patent B2

US 9,967,939 · App. 15/048,388 · Granted May 8, 2018

Abstract

Claims (42)

1. A thermal foldback control circuit electrically connected to a light emitting diode (LED) driver, the thermal foldback control circuit comprising:

a voltage divider including

a first resistor component having a first resistance that varies in response to a temperature at a reference point,

a second resistor component in a series-type configuration with the first resistor component, the second resistor component having a second resistance that varies in response to the temperature at the reference point, and

an output configured to output a reference voltage based on the first resistance and the second resistance; and

a shunt regulator in a parallel-type configuration with the voltage divider, the shunt regulator configured to

receive the reference voltage, and

control a driver output of the LED driver based on the reference voltage.

2. The thermal foldback control circuit of claim 1 , wherein the driver output powers one or more light emitting diodes (LEDs).

3. The thermal foldback control circuit of claim 1 , wherein the first resistor component is at least one selected from the group consisting of a negative temperature coefficient (NTC) type thermistor and a positive temperature coefficient (PTC) type thermistor.

4. The thermal foldback control circuit of claim 1 , wherein the second resistor component is at least one selected from the group consisting of a negative temperature coefficient (NTC) type thermistor and a positive temperature coefficient (PTC) type thermistor.

5. The thermal foldback control circuit of claim 1 , wherein the shunt regulator includes at least one selected from the group consisting of a Zener diode, an avalanche breakdown diode, and a voltage regulator tube.

6. The thermal foldback control circuit of claim 1 , wherein the shunt regulator decreases a drive current in response to the reference voltage crossing a predetermined threshold.

7. The thermal foldback control circuit of claim 6 , wherein the predetermined threshold is related to a predetermined temperature at the reference point.

8. The thermal foldback control circuit of claim 1 , wherein the reference point is located at at least one selected from the group consisting of the LED driver and an LED engine.

9. The thermal foldback control circuit of claim 1 , further comprising a capacitor in a parallel-type configuration with the second resistor.

10. A light emitting diode (LED) system comprising:

one or more light emitting diodes (LEDs);

an LED driver providing power to the one or more LEDs;

a thermal foldback control circuit electrically connected to the LED driver, the thermal foldback control circuit configured to output a control signal to the LED driver based on a temperature at a reference point, wherein the thermal foldback control circuit includes a voltage divider having

a first resistor component having a first resistance that varies in response to the temperature at the reference point, and

a second resistor component in a series-type configuration with the first resistor component, the second resistor component having a second resistance that varies in response to the temperature at the reference point.

11. The LED system of claim 10 , wherein the power provided to the one or more LEDs is based on the control signal.

12. The LED system of claim 10 , wherein the thermal foldback control circuit includes

the voltage divider further including

an output configured to output a reference voltage based on the first resistance and the second resistance; and

a shunt regulator in a parallel-type configuration with the voltage divider, the shunt regulator configured to

receive the reference voltage, and

output the control signal based on the reference voltage.

13. The LED system of claim 10 , wherein the control signal dims the one or more light emitting diodes when the temperature crosses a temperature threshold.

14. The LED system of claim 10 , wherein the control signal prohibits power to the one or more light emitting diodes when the temperature crosses a temperature threshold.

15. The LED system of claim 10 , wherein the reference point is located at at least one selected from the group consisting of the LED driver and an LED engine.

16. The LED system of claim 10 , wherein the LED driver includes a dimmer interface and the thermal foldback control circuit is electrically connected to the LED driver through the dimmer interface.

17. A method of controlling power to one or more light emitting diodes (LEDs), the method comprising:

sensing a temperature at a reference point;

comparing, via a thermal foldback control circuit, the sensed temperature to a predetermined temperature threshold, wherein the thermal foldback control circuit includes a voltage divider having

a first resistor component having a first resistance that varies in response to the temperature at the reference point, and

a second resistor component in a series-type configuration with the first resistor component, the second resistor component having a second resistance that varies in response to the temperature at the reference point; and

reducing power to the one or more LEDs when the sensed temperature passes the predetermined temperature threshold.

18. The method of claim 17 , further comprising

returning power to the one or more LEDs to a normal level when the sensed temperature is below the predetermined temperature threshold.

19. The method of claim 17 , wherein the reference point is located at at least one selected from the group consisting of an LED driver and an LED engine.

Assignments (6)