We analyze the thermal characteristics of 1 W GaN-LED as function of input power. Based on the transient thermal measurement
the relationship of junction-ambient thermal resistance and input power is discussed. The thermal resistance and the thermal capacitance in the heat flow path can be captured by the diffe-rential structure function and cumulative structure function
offering reliable evidence for thermal management. The devices exhibit a decrease of effective thermal resistance from 14.3 K/W to 12.5 K/W when the input current increases from 100 mA to 500 mA at the heatsink temperature of 25 ℃. However the effective thermal resistance gradually decrease from 12.5 K/W to 12.3 K/W with the input current from 500 mA to 800 mA. On the other hand
when the input current increases from 900 mA to 1 650 mA
the change trend is completely opposite
while the device exhibits an increase of effective thermal resistance from 14.7 K/W to 15.4 K/W. With the same devices
the different trends of thermal resistance go with different current regions. All packaged LEDs can be simplified to the model composed of an ideal diode and a series resistance.
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references
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