The use of LEDs has been increasing dramatically over the last few years. At the beginning, heat dissipation from LED junction was not a problem because low-power LEDs were used. However, modern high-power LEDs dissipate much higher portion of heat which has to be removed from the junction in order to maintain high efficacy, reliability and lifetime of LED-based light source.
Basic parameters to evaluate LED performance are (Figure 3.4.1):
• Junction temperature – Tj
• Thermal resistance – Rj-a
|Junction Temperature||Thermal resistance|
Figure 3.4.1: Basic parameters to evaluate LED performance.