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US 2016/0105936 A1Published application
Ripple reduction in light emitting diode (led)-based light bulb through increased ripple on an energy storage capacitor
AssigneeCirrus Logic, Inc.
InventorJohn L. Melanson
Life of this patent
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Abstract
A buck stage configured as a second stage of a lamp circuit for a light-emitting diode-based (LED-based) light bulb may reduce manufacturing costs associated with the bulb by reducing a size of a capacitor in the lamp circuit. A controller of the buck stage may adjust a duty cycle of a switch to increase a ripple, such as a voltage ripple, across the capacitor to increase accessibility of energy stored in the capacitor and decrease a ripple, such as in output current, to the LEDs.
Claims27
An apparatus, comprising:
- a line voltage input node configured to receive a line voltage input;
- a rectifier coupled to the line voltage input node;
- a first switching stage coupled to the rectifier and configured to regulate an approximately average current to an intermediate node;
- a capacitor coupled to the intermediate node;
- a second switching stage coupled to the intermediate node and configured to provide an approximately constant ratio of input to output current, wherein the second switching stage comprises a switch in series with a lighting load;
- a first controller coupled to the first switching stage and configured to regulate the first switching stage to maintain an approximately average current out of the first switching stage and into the intermediate node, the average current being averaged over each half line cycle of the input line voltage;
- and
- a second controller coupled to the switch, wherein the second controller is configured to operate the switch to control a ripple on the capacitor to reduce a ripple through the lighting load.
5 more elements
(canceled)
(canceled)
A method, comprising:
- regulating a current to an intermediate node in a first switching stage of a lamp to maintain an approximately average current for each half line cycle of an input line voltage;
- delivering current from the intermediate node to a second switching stage of the lamp;
- and
- regulating a ripple in an energy storage capacitor of the second switching stage of the lamp to provide an approximately constant ratio of input to output current.
1 more element
An apparatus, comprising:
- a first printed circuit board (PCB):
- a line voltage input node configured to receive a line voltage input;
- a rectifier coupled to the line voltage input node;
- a first switching stage coupled to the rectifier and configured to maintain an approximately average current for each one half of a cycle of the input live voltage;
- a transformer coupled to the first switching stage;
- and
- a second printed circuit board (PCB) galvanically isolated from the first printed circuit board (PCB), the second printed circuit board (PCB) comprising:
- a lighting output node configured to provide an output current;
- a second switching stage coupled to the transformer to receive an input current from the first printed circuit board (PCB) and configured to provide an approximately constant ratio of input current to output current;
- and
- a controller coupled to the second switching stage and configured to operate the second switching stage at approximately a constant average duty cycle over a period of at least one half of a cycle of the line voltage input,
- wherein the second switching stage of the second printed circuit board (PCB) is coupled to the first switching stage of the first printed circuit board (PCB) by two wires.
9 more elements
Dependencies are inferred from the claim text.