U.S. Department of Energy -
What Determines Junction Temperature?
Three things affect the junction temperature of an LED: drive current, thermal path, and ambient temperature. In general, the higher the drive current, the greater the heat generated at the die.
Heat must be moved away from the die in order to maintain expected light output, life, and color. The amount of heat that can be removed depends upon the ambient temperature and the design of the thermal path from the die to the surroundings.
The typical high-
The size of the heat sink is dependent upon the amount of heat to be dissipated and the material's thermal properties. Heat management and an awareness of the operating environment are critical considerations to the design and application of LED luminaires for general
illumination. Successful products will use superior heat sink designs to dissipate heat, and minimize Tj. Keeping the Tj as low as possible and within manufacturer specifications is necessary in order to maximize the performance potential of LEDs.