Circuit for detection and control of led string operation
AssigneeMicrochip Technology Incorporated
InventorJames T. Walker
Life of this patent
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Abstract
A circuit is disclosed for determining which of a multiplicity of LED strings in an illumination system has a fault. A group of circuits determines the maximum, minimum, midpoint between maximum and minimum, and average voltage of the group of LED string voltages in use, and examines the statistical properties of the LED string voltages. Comparators are used to find the strings which have the highest and lowest operating voltages, and to compare the midpoint and average voltages to determine whether the highest or lowest voltage string is responsible for causing a fault in the illumination system operation. Memory means are used to keep the said determined string turned off to prevent faulty operation.
Claims25
An LED system, comprising:
- a plurality of sets of LED devices, wherein each set comprises one or more LED devices;
- a detector circuit for detecting the maximum voltage associated with said plurality of sets;
- and
- a controller for disabling one of said plurality of sets in response to an output of said detector circuit.
An LED system, comprising:
- a plurality of sets of LED devices, wherein each set comprises one or more LED devices;
- a detector circuit for detecting the minimum voltage associated with said plurality of sets;
- and
- a controller for disabling one of said plurality of sets in response to an output of said detector circuit.
An LED system, comprising:
- a plurality of sets of LED devices, wherein each set comprises one or more LED devices;
- an average detector circuit for determining the average of the voltages associated with said plurality of sets;
- a controller for determining the cause of a fault in said LED system in response to an output of said detector circuit.
An LED system comprising:
- a plurality of sets of LED devices, wherein each set comprises one or more LED devices;
- an average circuit for generating an average voltage that is an average of the voltages across each set;
- a maximum detector circuit for detecting the maximum voltage across said sets;
- a minimum detector circuit for detecting the minimum voltage across said sets;
- a weighted average circuit for generating a weighted average voltage that is a weighted average of said maximum voltage and said minimum voltage;
- and
- a comparator for comparing the weighted average voltage and the average voltage to indicate a cause of a fault in the LED system.
Dependencies are inferred from the claim text.