Closed-loop load control circuit having a wide output range
First Claim
1. A load control circuit for controlling the amount of power delivered to an electrical load, the load control circuit comprising:
- a regulation transistor adapted to be coupled in series with the load to control the magnitude of a load current conducted through the load, so as to control the amount of power delivered to the load; and
a feedback circuit coupled in series with the regulation transistor and operable to generate a first load current feedback signal representative of the magnitude of the load current;
wherein the regulation transistor operates in the linear region in response to the magnitude of the load current determined from the first load current feedback signal, such that the load control circuit is able to control the magnitude of the load current conducted through the load from a minimum load current to a maximum load current, the maximum load current at least approximately one thousand times larger than the minimum load current.
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Accused Products
Abstract
A load control circuit, such as a light-emitting diode (LED) driver, for controlling the amount of power delivered to an electrical load, such as an LED light source, comprises a regulation transistor adapted to be coupled in series with the load, and a feedback circuit coupled in series with the regulation transistor, whereby the load control circuit is able to control the magnitude of a load current conducted through the load from a minimum load current to a maximum load current, which is at least approximately one thousand times larger than the minimum load current. The feedback circuit generates at least one load current feedback signal representative of the magnitude of the load current. The regulation transistor operates in the linear region to control the magnitude of the load current conducted through the load in response to the magnitude of the load current determined from the load current feedback signal.
183 Citations
55 Claims
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1. A load control circuit for controlling the amount of power delivered to an electrical load, the load control circuit comprising:
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a regulation transistor adapted to be coupled in series with the load to control the magnitude of a load current conducted through the load, so as to control the amount of power delivered to the load; and a feedback circuit coupled in series with the regulation transistor and operable to generate a first load current feedback signal representative of the magnitude of the load current; wherein the regulation transistor operates in the linear region in response to the magnitude of the load current determined from the first load current feedback signal, such that the load control circuit is able to control the magnitude of the load current conducted through the load from a minimum load current to a maximum load current, the maximum load current at least approximately one thousand times larger than the minimum load current. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. An LED driver for controlling an LED light source, the LED driver comprising:
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a power converter circuit operable to receive a rectified AC voltage and to generate a DC bus voltage; a LED drive circuit operable to receive the bus voltage and to control the magnitude of a load current conducted through the LED light source, the LED drive circuit comprising a feedback circuit operable to generate first and second load current feedback signals representative of the magnitude of the load current, the first and second load current feedback signals characterized by respective first and second gains applied to the magnitude of the load current, the first gain different than the second gain; and a control circuit operable to combine the first and second load current feedback signals, the control circuit operatively coupled to the LED drive circuit for controlling the magnitude of the load current through the load in response to both the first and second load current feedback signals, such that the LED drive circuit is able to control the magnitude of the load current conducted through the load from a minimum load current to a maximum load current. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25, 26, 27)
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28. A load control circuit for controlling the amount of power delivered to an electrical load, the load control circuit comprising:
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a regulation transistor adapted to be coupled in series with the load to control the magnitude of a load current conducted through the load, so as to control the amount of power delivered to the load; a feedback circuit coupled in series with the regulation transistor and operable to generate first and second load current feedback signals representative of the magnitude of the load current, the first and second load current feedback signals characterized by respective first and second gains with respect to the magnitude of the load current, the first gain different than the second gain; and a control circuit operable to combine the first and second load current feedback signals to determine the magnitude of the load current in response to both the first and second load current feedback signals, the control circuit operatively coupled to the regulation transistor for controlling the regulation transistor to operate in the linear region to thus adjust the magnitude of the load current through the load in response to the magnitude of the load current determined from the first and second load current feedback signals. - View Dependent Claims (29, 30, 31, 32, 33, 34, 35, 36, 37)
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38. A load control circuit for controlling the amount of power delivered to an electrical load, the load control circuit comprising:
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a regulation transistor adapted to be coupled in series with the load to control the magnitude of a load current conducted through the load, so as to control the amount of power delivered to the load; an adjustable-gain feedback circuit coupled in series with the regulation FET and operable to generate a load current feedback signal representative of the magnitude of the load current, the adjustable-gain feedback circuit comprising first and second resistors coupled in series with the regulation FET, and a gain-adjustment transistor coupled across the second resistor; a control circuit operatively coupled to the regulation transistor for controlling the regulation transistor to thus adjust the magnitude of the load current through the load, the control circuit further coupled to the adjustable-gain feedback circuit for rendering the gain-adjustment transistor conductive and non-conductive, such that the series combination of the first and second resistors is coupled in series with the regulation FET when the gain-adjustment transistor is non-conductive, and only the first resistor is coupled in series with the regulation FET when the gain-adjustment transistor is conductive; and wherein the control circuit is operable to; generate a current control signal for controlling the regulation transistor to operate in the linear region to thus control the magnitude of the load current conducted through the load; detect that the magnitude of the load current is less than the threshold current; subsequently pause controlling the regulation transistor in response to the magnitude of the load current; adjust the magnitude of the current control signal by a predetermined amount; subsequently wait for a first delay time; and render the gain-adjustment transistor non-conductive at the end of the first delay time. - View Dependent Claims (39, 40, 41, 42, 43)
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44. A method of controlling the amount of power delivered to an electrical load, the method comprising:
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controlling the magnitude of a load current conducted through the load, so as to control the amount of power delivered to the load; generating first and second load current feedback signals representative of the magnitude of the load current, the first and second load current feedback signals characterized by respective first and second gains applied to the magnitude of the load current, the first gain different than the second gain; combining the first and second load current feedback signals; calculating the magnitude of the load current in response to combining both the first and second load current feedback signals; and adjusting the magnitude of the load current in response to the calculated magnitude of the load current determined from the first and second load current feedback signals. - View Dependent Claims (45, 46, 47, 48, 49, 50, 51)
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52. A method of controlling the amount of power delivered to an electrical load, the method comprising:
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controlling the magnitude of a load current conducted through the load by controlling a regulation transistor coupled so as to conduct the load current to operate in the linear region, so as to control the amount of power delivered to the load; conducting the load current through first and second series-connected resistors; generating a load current feedback signal across the series-connected resistors, the load current feedback signal representative of the magnitude of the load current; the load current feedback signal comprising a first load current feedback signal developed across a first resistor and a second load current feedback signal developed across both resistors in series; calculating the magnitude of the load current in response to both load current feedback signals; adjusting the magnitude of the load current in response to the magnitude of the load current determined from the first and second load current feedback signals; controlling a gain-adjustment transistor coupled across the second resistor to be conductive, such that the first load current feedback signal is generated from only the first resistor; generating a current control signal for controlling the regulation transistor to operate in the linear region to thus control the magnitude of the load current conducted through the load; detecting that the magnitude of the load current is less than the threshold current; subsequently pausing controlling the regulation transistor in response to the magnitude of the load current; adjusting the magnitude of the current control signal by a predetermined amount; subsequently waiting for a first delay time; and rendering the gain-adjustment transistor non-conductive at the end of the first delay time, such that the load current feedback signal is generated across the series combination of the first and second resistors. - View Dependent Claims (53, 54)
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55. A load control circuit for controlling the amount of power delivered to an electrical load, the load control circuit comprising:
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a regulation transistor adapted to be coupled in series with the load to control the magnitude of a load current conducted through the load, so as to control the amount of power delivered to the load; a control circuit operatively coupled to the regulation transistor, the control circuit generating a current control signal for controlling the regulation transistor to operate in the linear region to thus adjust the magnitude of the load current through the load and an adjustable-gain feedback circuit coupled in series with the regulation transistor and operable to generate a load current feedback signal representative of the magnitude of the load current, the adjustable-gain feedback circuit characterized by a first gain and characterized by a second gain; wherein the control circuit is operable to; control the adjustable-gain feedback circuit to be characterized by the first gain; detect that the magnitude of the load current is less than a threshold current; subsequently pause controlling the regulation transistor in response to the magnitude of the load current; adjust the magnitude of the current control signal by a predetermined amount; subsequently wait for a first delay time; and control the adjustable-gain feedback circuit to be characterized by the second gain.
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Specification