Doug S
Flashlight Enthusiast
I recently checked the Luxeon site to see if there had been any datasheet updates. The datasheets that I had previously downloaded for the 1W and 5W devices were both dated 05/02. There are now updated datasheets dated 07/02. I have checked them for differences and the only change I find is on the 5W datasheets. For the 5W devices the min to max range for Vf@700 mA has been increased to 5.43-8.31V. Formerly it had been 5.43-7.83V. This change surprised me since I already thought the range was larger than one would expect from the process variations in die fab. Also on their site are a couple of Applications Briefs that are new since my last visit. For some heavy technogeek reading, check out AB8, Optical Testing. Anyone planning working with the 5W devices should check AB23, Thermal Design Considerations for 5W Power Light Sources. The later has some test data for the junction-ambient thermal resistances obtained with the 5W devices mounted on some pretty large heatsinks [photos included] with and without forced air cooling. Without forced air, 20C/W J-A was obtained with a commercial heatsink with 36 sq in of cooling area. So, with this heatsink, you hotrod modders would be looking at a cooking 125C junction temp in a 25C ambient if running at 5W. At this temp, your luminous flux is down to about 68% of the datasheet [25C] value. This should definitively answer the question that came up awhile back on the homemade/Mod board about whether the MiniMag was a suitable platform in which to drive a 5W device hard. No.
