SMJE-2V08W1P3 Datasheet, PDF (7/17 Pages) Seoul Semiconductor – Acrich2 series designed for AC drive(or operation)...

2. Thermal Resistance of 8.7W
Acrich2 LED, which has 27℃/W thermal resistance from junction to LED lead.
The maximum junction temperature of Acrich2 LED package is 125℃. So permissible max lead
temperature T_{s_max} is
T_{s_max} = T_{j_max} - (Rq_j-s * P_D)
= 125℃ - (27℃/W * 0.5W) = 111.5℃
But, Recommendation of LED lead temperature is under 70℃
Acrich2 IC, which has 5.5℃/W thermal resistance from junction to top surface.
The maximum junction temperature of its IC is 125℃. So allowable Acrich2 IC top surface
temperature (T_{t_max}) is
T_{t_max} = T_{j_max} - (y_j-t * P_D)
= 125℃ - (5.5℃/W * 1.5W) = 116.8℃
Rev. 01
June 2012
7
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