| 摘要 |
An instrument measures the LED junction temperature directly by taking advantage of the linear relationship between the forward current driven through the LED, the forward drop of the LED, and the junction temperature to determine the LED junction temperature. Calibration is conducted by placing two LEDs from the same family in ambient temperature and passing a small test current through each of the LEDs to obtain the forward drop of the LED at ambient temperature. The LED under test is then placed in an environmentally-controlled chamber where the temperature is raised a known amount above ambient temperature. Known low and high voltage values are associated with the ambient temperature and the environmental chamber temperature, causing the LED under test becomes a calibrated thermometer that can measure its own junction temperature due to the linear relationship between the forward drop and the junction temperature.
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