Light emitting diode thermal foldback control device and method

Patent metadata

Field	Value
Publication number	US-2018242420-A1
Application number	US-201815961050-A
Country	US
Kind code	A1
Filing date	Apr 24, 2018
Priority date	Feb 20, 2015
Publication date	Aug 23, 2018
Grant date	—

Abstract

A thermal foldback control system electrically connected to a light emitting diode (LED) driver. The thermal foldback control system including a temperature sensitive circuit and a shunt regulator. The temperature sensitive circuit includes first and second resistances that vary in response to a temperature at a reference point. Wherein the temperature sensitive circuit outputs a reference voltage based on the first and second resistances. The shunt regulator is configured to control a driver output of the LED driver based on the reference voltage.

First claim

What is claimed is:

1 . A thermal foldback control system electrically connected to a light emitting diode (LED) driver, the thermal foldback control system comprising:
a temperature sensitive circuit having first and second resistances that vary in response to a temperature at a reference point, wherein the temperature sensitive circuit outputs a reference voltage based on the first and second resistances; and a shunt regulator configured to 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; and a temperature sensitive circuit having first and second resistances that vary in response to a temperature at a reference point, wherein the temperature sensitive circuit outputs a control signal to the LED driver, the control signal based on the temperature at the reference point.

11 . The LED system of claim 10 , wherein the temperature sensitive circuit includes
a voltage divider including
a first resistor component having the first resistance that varies in response to the temperature at the reference point,
a second resistor component having the second resistance that varies in response to the temperature at the reference point, and
a shunt regulator in a parallel-type configuration with the voltage divider, the shunt regulator configured to
receive a reference voltage from the voltage divider, and
output the control signal based on the reference voltage.

12 . 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.

13 . 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.

14 . 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.

15 . 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.

16 . A method of controlling power to one or more light emitting diodes (LEDs), the method comprising:
sensing a temperature at a reference point; outputting, via a temperature-sensitive circuit, a control signal based on a first and second resistance; and controlling, via a LED driver, one or more LEDs based on the control signal; wherein the first and second resistances vary in response to the temperature at the reference point.

17 . The method of claim 16 , wherein the temperature sensitive circuit includes
a voltage divider including
a first resistor component having the first resistance that varies in response to the temperature at the reference point,
a second resistor component having the second resistance that varies in response to the temperature at the reference point, and
a shunt regulator in a parallel-type configuration with the voltage divider, the shunt regulator configured to
receive a reference voltage from the voltage divider, and output the control signal based on the reference voltage.

18 . The method of claim 16 , wherein the step of controlling the one or more LEDs includes
reducing power to the one or more LEDs when the temperature at the reference point crosses a predetermined threshold.

19 . The method of claim 18 , wherein the step of controlling the one or more LEDs includes
returning power to the one or more LEDs to a normal level when the temperature at the reference point is below the predetermined temperature threshold.

20 . The method of claim 16 , wherein the reference point is located at at least one selected from the group consisting of an LED driver and an LED engine.

Assignees

• Hubbell Inc

Inventors

• Bandel Michael W
• Lazalier Ray M

Classifications

• H05B33/0854

  Electricity · mapped topic

• H05B33/0809

  Electricity · mapped topic

• H05B33/0851 Primary

  Electricity · mapped topic

• H05B45/56

  involving measures to prevent abnormal temperature of the LEDs · CPC title

• H05B45/30

  Driver circuits · CPC title