Temperature has a direct impact on optical and electrical performance as well as on the overall quality and reliability of an LED-based product. Therefore, it is critical that engineering teams understand the system’s thermal parameters, and focus on thermodynamic competencies.
These parameters are all interconnected. For example, a higher drive current should increase the light output of the LED. However, the higher current increases the dissipated power, causing heating within the LED, which has a negative impact on light output. Also, conversely, a higher junction temperature (caused for example by a higher ambient temperature) causes a reduction in the LED’s forward voltage, reducing the dissipated power for a constant-current source.
This article was published in the April 2009 issue of LEDs Magazine.
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