Lighting system and method for dynamically regulating driven current to an analog or digital dimming interface

Patent metadata

Field	Value
Publication number	US-10264641-B1
Application number	US-201715825944-A
Country	US
Kind code	B1
Filing date	Nov 29, 2017
Priority date	Jul 5, 2017
Publication date	Apr 16, 2019
Grant date	Apr 16, 2019

Abstract

A lighting system includes various ballasts or LED drivers having respective dimming interface circuits coupled in parallel to an external dimming device. Each device includes a controller regulating output to a lighting load based on desired dimming output. Dimming interface circuits coupled are between the controller and the external dimming device, each configured to dynamically adapt a level of constant current sourced from the dimming interface circuit to the external dimming device via first and second interface terminals, based on a determined analog mode or digital mode associated with the external device. The dimming interface circuit generates dimming control signals to the controller based on dimming input signals received via the first and second interface terminals, and in a digital mode, the interface circuit generates digital pulse signals to the external dimming device via the interface terminals for bidirectional communications therewith.

First claim

What is claimed is:

1. A lighting device comprising:
a power converter configured to provide output power to a lighting load;
a controller configured to regulate operation of the power converter based at least in part on a desired dimming output for the lighting load; and
a dimming interface circuit comprising:
a first circuit coupled across the first and second interface terminals and comprising at least one switching element controlled on and off to regulate a level of current sourced from the dimming interface circuit to an external dimming device coupled across the first and second interface terminals, and
a second circuit coupled in parallel with the first circuit and configured to measure a control voltage across the first and second interface terminals,

wherein the dimming interface circuit is configured to
automatically detect a type of external dimming device coupled to the first and second interface terminals as being
analog, based on a sampled measurement of the control voltage across the first and second interface terminals as having a calculated ramp slope greater than a threshold value, or
digital, based on the sampled measurement of the control voltage across the first and second interface terminals as having the calculated ramp slope less than the threshold value,

dynamically adapt a level of constant current sourced from the dimming interface circuit to the external dimming device via the first and second interface terminals, based at least on the detected type of the external dimming device being analog or digital, and
generate dimming control signals to the controller based on dimming input signals from the external dimming device via the first and second interface terminals.

2. The lighting device of claim 1 , comprising a plurality of switching elements coupled in series with the first interface terminal,
wherein at least a first switching element of the plurality of switching elements is controlled on and off to regulate the current source level, and
wherein at least a second switching element of the plurality of switching elements is controlled on and off to generate a digital pulse stream for bidirectional communications with a digital type of external dimming device.

3. The lighting device of claim 2 , further comprising voltage protection circuitry coupled between the second switching element and the first interface terminal and configured in association with operation of at least the second switching element to withstand a misapplication of mains input voltage across the first and second interface terminals.

4. The lighting device of claim 3 , wherein the voltage protection circuitry comprises a third switching element and a reverse bias current blocking diode coupled in series between the second switching element and the first interface terminal.

5. The lighting device of claim 4 , wherein the second switching element is controlled, responsive to a detected short across the first and second interface terminals, to alternatively open so as to reduce stress to the third switching element and close so as to determine a continued presence of the detected short.

6. The lighting device of claim 4 , further comprising a thermal compensation circuit configured to compensate for errors caused by temperature-driven changes in voltage across the third switching element, the thermal compensation circuit comprising a fourth switching element coupled to a control electrode of the third switching element.

7. A lighting device comprising:
a power converter configured to provide output power to a lighting load;
a controller configured to regulate operation of the power converter based at least in part on a desired dimming output for the lighting load; and
a dimming interface circuit comprising:
a first circuit coupled across the first and second interface terminals and comprising at least one switching element controlled on and off to regulate a level of current sourced from the dimming interface circuit to an external dimming device coupled across the first and second interface terminals,
a second circuit coupled in parallel with the first circuit and configured to measure a control voltage across the first and second interface terminals, and
a third circuit configured to measure an amount of current consumed by the dimming interface circuit,

wherein the dimming interface circuit is configured to
automatically detect a type of external dimming device coupled to the first and second interface terminals based on the measured control voltage across the first and second interface terminals and the measured amount of current consumed by the dimming interface circuit,
dynamically adapt a level of constant current sourced from the dimming interface circuit to the external dimming device via the first and second interface terminals, based at least on the detected type of the external dimming device being analog or digital, and
generate dimming control signals to the controller based on dimming input signals from the external dimming device via the first and second interface terminals.

8. The lighting device of claim 7 , wherein the first circuit comprises first and second resistors coupled in series to a first input voltage terminal, and the first circuit comprises a first switching element coupled in parallel with the second resistor and at least a second switching element coupled between the second resistor and the first interface terminal,
wherein the third circuit is configured to compare an input voltage to the dimming interface circuit against a voltage across the first and second resistors.

9. The lighting device of claim 7 , comprising a plurality of switching elements coupled in series with the first interface terminal,
wherein at least a first switching element of the plurality of switching elements is controlled on and off to regulate the current source level, and
wherein at least a second switching element of the plurality of switching elements is controlled on and off to generate a digital pulse stream for bidirectional communications with a digital type of external dimming device.

10. The lighting device of claim 9 , further comprising voltage protection circuitry coupled between the second switching element and the first interface terminal and configured in association with operation of at least the second switching element to withstand a misapplication of mains input voltage across the first and second interface terminals.

11. The lighting device of claim 10 , wherein the voltage protection circuitry comprises a third switching element and a reverse bias current blocking diode coupled in series between the second switching element and the first interface terminal.

12. The lighting device of claim 11 , wherein the second switching element is controlled, responsive to a detected short across the first and second interface terminals, to alternatively open so as to reduce stress to the third switching element and close so as to determine a continued presence of the detected short.

13. The lighting device of claim 11 , further comprising a thermal compensation circuit configured to compensate for errors caused by temperature-driven changes in voltage across the third switching element, the thermal compensation circuit comprising a fourth switching element coupled to a control electrode of the third switching element.

14. A lighting device comprising:
a power converter configured to provide output power to a lighting load;
a controller configured to regulate operation of the power converter based at least in part on a desired dimming output for the lighting load;
first and second interface

Assignees

• Universal Lighting Tech Inc

Inventors

• Mays Ii Stephen D
• Dernovsek John J
• Gann Matthew
• Sutherland Ii Dane

Classifications

• H05B47/24

  Circuit arrangements for protecting against overvoltage · CPC title

• H05B47/18

  via data-bus transmission · CPC title

• H05B45/10 Primary

  Controlling the intensity of the light · CPC title

• H05B41/38

  Controlling the intensity of light · CPC title

• H05B33/0845 Primary

  Electricity · mapped topic