Current regulator for multimode operation of solid state lighting
View Patent ↗An exemplary apparatus embodiment provides a plurality of operating modes for solid state lighting, such as a flash mode and a constant or background lighting mode for use with devices such as cameras. An exemplary apparatus comprises a memory adapted to store a plurality of average current parameters; and a controller adapted to modulate an energizing cycle time period (“T”) for providing power to the solid state lighting as proportional to the product of the selected average current parameter (“a”) and a reset time period (“T R ”) for an inductor current to return to a substantially zero level from a predetermined peak level (T∝a·T R ). The average current parameter is predetermined as substantially proportional to a ratio of a peak inductor current level (“I P ”) to an average output D.C. current level ( “ I O ” ) ( a ∝ I P I O ) .
1. A current regulator for providing a plurality of operating modes for solid state lighting, the current regulator couplable to a DC power supply, the current regulator comprising:
a memory to store a plurality of average current parameters; and
a control circuit coupled to the memory, the control circuit to modulate an energizing cycle time period (“T”) for providing power to the solid state lighting in response to a selected average current parameter (“a”) of the plurality of average current parameters by determining the energizing cycle time period as proportional to the product of the selected average current parameter and a reset time period (“T R ”) for an inductor current to return to a substantially zero level from a predetermined peak level (T∝a·T R ).
2. The current regulator of claim 1 , wherein each average current parameter of the plurality of average current parameters corresponds to a selected operating mode of the plurality of operating modes.
3. The current regulator of claim 1 , wherein the plurality of operating modes comprises a flash mode and a constant mode.
4. The current regulator of claim 1 , wherein each average current parameter (“a”) of the plurality of average current parameters is predetermined as substantially equal to one-half of a ratio of a peak inductor current level (“I P ”) to an average output D.C. current level
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5. The current regulator of claim 1 , wherein each average current parameter (“a”) of the plurality of average current parameters is predetermined as substantially proportional to a ratio of a peak inductor current level (“I P ”) to an average output D.C. current level
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O
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a
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6. The current regulator of claim 5 , wherein the peak inductor current level (I P ) and the average output D.C. current level (I O ) are predetermined and correspond to a selected operating mode of the plurality of operating modes.
7. The current regulator of claim 1 , wherein the control circuit further comprises:
a first counter to provide a count corresponding to the energizing cycle time period (T n ); and
a second counter to provide a count corresponding to the reset time period (T R ).
8. The current regulator of claim 7 , wherein the control circuit further is to provide a next energizing cycle when a count T n of the first counter is equal to the energizing cycle time period T.
9. The current regulator of claim 1 , further comprising:
an inductor coupled to the DC power supply and coupled to the solid state lighting;
a switch coupled to the inductor and to the control circuit;
a current sensor coupled to the switch; and
a first comparator coupled to the current sensor and the control circuit;
wherein the control circuit further is to turn the switch on to commence an energizing cycle and to turn the switch off when the first comparator indicates that an inductor current has reached a predetermined peak level.
10. The current regulator of claim 9 , further comprising:
a voltage sensor; and
a second comparator coupled to the voltage sensor and to the control circuit;
wherein the control circuit further is to determine the reset time period (T R ) when the second comparator indicates that a voltage level corresponding to the inductor current has decreased substantially to a zero level.
11. An apparatus for providing a plurality of operating modes for solid state lighting, the apparatus comprising:
a memory to store a plurality of average current parameters; and
a controller coupled to the memory, the controller to modulate an energizing cycle time period (“T”) for providing power to the solid state lighting in response to a selected average current parameter (“a”) of the plurality of average current parameters by determining the energizing cycle time period as proportional to the product of the selected average current parameter and a reset time period (“T R ”) for an inductor current to return to a substantially zero level from a predetermined peak level (T∝a·T R ).
12. The apparatus of claim 11 , wherein each average current parameter of the plurality of average current parameters corresponds to a selected operating mode of the plurality of operating modes.
13. The apparatus of claim 11 , wherein the plurality of operating modes comprises a flash mode and a constant mode.
14. The apparatus of claim 11 , wherein each average current parameter (“a”) of the plurality of average current parameters is predetermined as substantially equal to one-half of a ratio of a peak inductor current level (“I P ”) to an average output D.C. current level
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O
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a
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P
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15. The apparatus of claim 11 , wherein the controller further comprises:
a first counter to provide a count corresponding to the energizing cycle time period (T n ); and
a second counter to provide a count corresponding to the reset time period (T R ).
16. The apparatus of claim 15 , wherein the controller further is to provide a next energizing cycle when a count T n of the first counter is equal to the energizing cycle time period T.
17. The apparatus of claim 11 , further comprising:
an inductor coupled to the DC power supply and coupled to the solid state lighting;
and wherein the controller further comprises:
a control circuit;
a switch coupled to the inductor and to the control circuit;
a current sensor coupled to the switch; and
a first comparator coupled to the current sensor and the control circuit;
wherein the control circuit is to turn the switch on to commence an energizing cycle and to turn the switch off when the first comparator indicates that an inductor current has reached a predetermined peak level.
18. The apparatus of claim 17 , wherein the controller further comprises:
a voltage sensor; and
a second comparator coupled to the voltage sensor and to the control circuit;
wherein the control circuit further is to determine the reset time period (T R ) when the second comparator indicates that a voltage level corresponding to the inductor current has decreased substantially to a zero level.
19. The apparatus of claim 11 , wherein each average current parameter (“a”) of the plurality of average current parameters is predetermined as substantially proportional to a ratio of a peak inductor current level (“I P ”) to an average output D.C. current level
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O
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20. The apparatus of claim 19 , wherein the peak inductor current level (I P ) and the average output D.C. current level (I O ) are predetermined and correspond to a selected operating mode of the plurality of operating modes.
21. The apparatus of claim 19 , wherein each predetermined average current parameter is determined by a corresponding peak inductor current level (I P ) of a plurality of peak inductor current levels (I P ) and an average output D.C. current level (I O ) of a plurality of and average output D.C. current levels (I O ).
22. A current regulator for providing a plurality of operating modes for solid state lighting, the current regulator couplable to a DC power supply, the current regulator comprising:
an inductor coupled to the DC power supply and coupled to the solid state lighting;
a switch coupled to the inductor;
a current sensor coupled to the switch;
a first comparator coupled to the current sensor;
a voltage sensor coupled to the inductor;
a second comparator coupled to the voltage sensor;
a memory to store a plurality of average current parameters; and
a control circuit coupled to the memory and to the first and second comparators, the control circuit to turn the switch on to commence an energizing cycle and to turn the switch off when the first comparator indicates that an inductor current has reached a predetermined peak level, to determine a reset time period when the second comparator indicates that a voltage level corresponding to the inductor current has decreased substantially to a zero level, and to determine an energizing cycle time period for providing power to the solid state lighting as proportional to a selected average current parameter of the plurality of average current parameters and the reset time period.