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1. WO2019059962 - LOAD CONTROL DEVICE HAVING A WIDE OUTPUT RANGE

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[ EN ]

What is claimed is:

CLAIMS

1. A load control device for controlling the intensity of a lighting load, the load control device comprising:

a load regulation circuit configured to control the magnitude of a load current conducted through the lighting load to adjust the intensity of the lighting load between a low-end intensity and a high-end intensity, the load regulation circuit characterized by an operating frequency;

a filter circuit configured to receive a current feedback signal from the load regulation circuit and to filter the current feedback signal to generate a filtered feedback signal; and

a control circuit operatively coupled to the load regulation circuit for controlling the magnitude of the load current towards a target current in response to the filtered feedback signal;

wherein the control circuit is configured to adjust the operating frequency of the load regulation circuit in response to the target current when the intensity of the lighting load is near the low-end intensity, the control circuit configured to control the filter circuit to filter the current feedback signal during a filter window that repeats on a periodic basis when the intensity of the lighting load is near the low-end intensity, the control circuit configured to control the filter circuit to constantly filter the current feedback signal when the intensity of the lighting load is near the high-end intensity.

2. The load control device of claim 1, wherein the control circuit is configured to adjust the operating frequency of the load regulation circuit in response to the target current when the magnitude of the target current is less than a transition current, the control circuit configured to control the filter circuit to filter the current feedback signal during the filter window when the magnitude of the target current is less than the transition current, the control circuit configured to control the filter circuit to constantly filter the current feedback signal when the magnitude of the target current is greater than the transition current.

3. The load control device of claim 2, wherein the load regulation circuit comprises a semiconductor switch and the control circuit is configured to render the semiconductor switch conductive for an on-time during each operating cycle of the load regulation circuit.

4. The load control device of claim 3, wherein, when the magnitude of the target current is greater than the transition current, the control circuit is configured to maintain the operating frequency of the load regulation circuit constant and adjust the on-time of the

semiconductor switch of the load regulation circuit in response to the target current.

5. The load control device of claim 4, wherein the control circuit is configured to adjust a magnitude of a target-current control signal to adjust the on-time of the semiconductor switch of the load regulation circuit when the magnitude of the target current is greater than the transition current.

6. The load control device of claim 5, wherein, when the magnitude of the target current is less than the transition current, the control circuit is configured to maintain the magnitude of the target-current control signal constant and adjust the operating frequency of the load regulation circuit in response to the target current.

7. The load control device of claim 4, wherein the control circuit comprises a digital control circuit configured to generate a target-current control signal and an analog control loop circuit configured to control the semiconductor switch of the load regulation circuit to control the magnitude of the load current in response to the target-current control signal.

8. The load control device of claim 7, wherein, when the magnitude of the target current is less than the transition current, the control circuit is configured to maintain the magnitude of the target-current control signal constant and adjust the operating frequency of the load regulation circuit in response to the target current.

9. The load control device of claim 2, wherein the control circuit is configured to control the filter circuit with a periodic signal when the magnitude of the target current is less than the transition current, and with a constant signal when the magnitude of the target current is greater than the transition current.

10. The load control device of claim 9, wherein the control circuit is configured to generate a frequency control signal for controlling the operating frequency of the load regulation circuit.

11. The load control device of claim 10, wherein the periodic signal for controlling the filter circuit has a constant on-time.

12. The load control device of claim 11, wherein the periodic signal for controlling the filter circuit is synchronized with the frequency control signal.

13. The load control device of claim 12, wherein the on-time of the periodic signal for controlling the filter circuit is equal to a minimum period of the frequency control signal.

14. The load control device of claim 9, wherein the filter circuit comprises a boxcar filter circuit.

15. A load control device for controlling the intensity of a lighting load, the load control device comprising:

a load regulation circuit configured to control the magnitude of a load current conducted through the lighting load to adjust the intensity of the lighting load;

a filter circuit configured to receive a current feedback signal from the load regulation circuit and to filter the current feedback signal to generate a filtered feedback signal; and

a control circuit operatively coupled to the load regulation circuit for controlling the magnitude of the load current towards a target current in response to the filtered feedback signal;

wherein the control circuit is configured to adjust an operating frequency of the load regulation circuit in response to the target current when the magnitude of the target current of the lighting load is less than a transition current, the control circuit configured to control the filter circuit to filter the current feedback signal during a filter window that repeats on a periodic basis when the magnitude of the target current of the lighting load is less than the transition current, the control circuit configured to control the filter circuit to constantly filter the current feedback signal when the magnitude of the target current of the lighting load is greater than the transition current.

16. The load control device of claim 15, wherein the control circuit is configured to: render a semiconductor switch of the load regulation circuit conductive for an on-time during each operating cycle of the load regulation circuit;

when the magnitude of the target current is greater than the transition current, maintain the operating frequency of the load regulation circuit constant and adjust the on-time of the semiconductor switch of the load regulation circuit in response to the target current; and

when the magnitude of the target current is less than the transition current, adjust the operating frequency of the load regulation circuit in response to the target current.

17. The load control device of claim 15, wherein the control circuit is configured to control the filter circuit with a periodic signal when the magnitude of the target current is less than the transition current, and with a constant signal when the magnitude of the target current is greater than the transition current.

18. A load control device for controlling the intensity of a lighting load, the load control device comprising:

a load regulation circuit configured to control the magnitude of a load current conducted through the lighting load to adjust the intensity of the lighting load between a low-end intensity and a high-end intensity;

a filter circuit configured to receive a current feedback signal from the load regulation circuit and to filter the current feedback signal to generate a filtered feedback signal; and

a control circuit operatively coupled to the load regulation circuit for controlling the magnitude of the load current towards a target current in response to the filtered feedback signal;

wherein the control circuit is configured to adjust an operating frequency of the load regulation circuit in response to the target current when the magnitude of the target current is less than a transition current, the control circuit configured to generate a filter control signal for controlling the filter circuit to filter the current feedback signal during a filter window that repeats on a periodic basis when the magnitude of the target current is less than a transition current, the control circuit configured to control the filter control signal to have a maximum duty cycle when the magnitude of the target current is greater than the transition current.

19. The load control device of claim 18, wherein the filter control signal is a periodic signal when the target current is less than the transition current and a constant signal when the target current is greater than the transition current.

20. The load control device of claim 19, wherein the control circuit is configured to generate a frequency control signal for controlling the operating frequency of the load regulation circuit, the control circuit configured to control the periodic signal to have a constant on-time and to be synchronized with the frequency control signal.

21. The load control device of claim 20, wherein the maximum duty cycle is 100%.

22. The load control device of claim 20, wherein the maximum duty cycle is greater than approximately 90%.