Fault protected current source for lighting element testing
First Claim
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1. A fault protected current source, comprising:
- a positive current output and a negative current output configured to provide an operating current and operating voltage to a load;
a DC-DC converter configured to receive a control signal from a processor and to adjust an output voltage of the current source in response to the control signal;
an over current detection module configured to monitor current through the positive or negative current output and to compare the current to a control current indicated by a current level control signal provided by the processor; and
the processor configured to monitor voltage across the positive current output and the negative current output to determine a steady state voltage across the load and to provide the control signal to the DC-DC converter to set the output voltage at a predetermined voltage level above the steady state voltage, and further configured to provide the current level control signal to the over current detection module.
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Abstract
A fault protected current source is provided that can be used to safely drive LEDs in reliability test systems. The current source is includes circuits and processes that detect the common faults found in LED reliability test systems. After a fault is detected, the current source shuts down drive before destructive spikes are produced. Because only true LED failures are counted, this fault protected current source can be used to construct reliability test systems that produce more accurate reliability test data.
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Citations
29 Claims
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1. A fault protected current source, comprising:
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a positive current output and a negative current output configured to provide an operating current and operating voltage to a load; a DC-DC converter configured to receive a control signal from a processor and to adjust an output voltage of the current source in response to the control signal; an over current detection module configured to monitor current through the positive or negative current output and to compare the current to a control current indicated by a current level control signal provided by the processor; and the processor configured to monitor voltage across the positive current output and the negative current output to determine a steady state voltage across the load and to provide the control signal to the DC-DC converter to set the output voltage at a predetermined voltage level above the steady state voltage, and further configured to provide the current level control signal to the over current detection module. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A method of operating a current source, comprising:
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providing an operating current and operating voltage to a load through a positive current output and a negative current output; adjusting an output voltage of a DC-DC converter in response to a control signal from a processor received by the DC-DC converter; an over current detection module monitoring the current through the positive or negative current output and comparing the current to a control current indicated by a current level control signal provided by the processor; the processor monitoring voltage across the positive current output and the negative current output to determine a steady state voltage across the load and providing the control signal to the DC-DC converter to set the output voltage at a predetermined voltage level above the steady state voltage; and the processor providing the current level control signal to the over current detection module. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29)
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Specification