Is a LuxIII Better At Dealing w/ Heat Than a LuxI?

Is the LuxIII better at taking the higher current/heat than the LuxI or is it just that the LuxI is binned at a certain flux at 350ma...

Hello jar3ds

Go with U-bins and a PTS heatsink for you Trilux setup. There are no heat problems


Best regards

____
Tom

with a LuxIII and LuxI running at the same current/Vf the LuxIII will be more efficient..

I heard lux I and Lux III are the same creature all together. They just get binned differently, one at 350 mA, the other at 700 mA.

"Is the LuxIII better at taking the higher current/heat than the LuxI..."

Basically the answer is yes, but the difference is not very big. According to datasheets the junction-to-case thermal resistance is 15C/W for Lux1 and 13C/W for Lux3. If, for example, you run both lux1 and lux3 at 3 watts and keep the slug temps at e.g. 40C, the Lux1 junction is running at 85C and the Lux3 junction is running at 79C.

Hope this helps.

-N

Check out this thread, the first post should say it all. Lux I bins running at 350mA to led can be more efficient than Lux III's running at 350mA's to led. Great info here: http://candlepowerforums.com/vb/showthread.php?p=1442127#post1442127

Nereus said:

"Is the LuxIII better at taking the higher current/heat than the LuxI..."

Basically the answer is yes, but the difference is not very big. According to datasheets the junction-to-case thermal resistance is 15C/W for Lux1 and 13C/W for Lux3. If, for example, you run both lux1 and lux3 at 3 watts and keep the slug temps at e.g. 40C, the Lux1 junction is running at 85C and the Lux3 junction is running at 79C.

Hope this helps.

-N

Click to expand...

For the star or emitter? Luxeon III is shipped with a thicker "star" heatsink on the star version.

Those figures are taken from emitter datasheets.

-N

I had a quick look on the Luxeon star datasheets: junction-to-board thermal resistance is 17C/W for lux3 and 20C/W for lux1. So quite a small difference here again.

-N

The Luxeon data sheets might be "out of date".

If I recall correctly - and maybe I don't - the LuxI LED die was originally mounted on an all aluminum slug, while the LuxIII was mounted on a plated copper slug. This might account for the quoted difference in thermal resistance.

Nowadays, the LuxI is mounted on a plated copper slug just like the LuxIII. Perhaps Lumileds just hasn't had the time to update the data sheets, or perhaps they aren't anxious to do so, lest buyers figure out that there really is no difference between a cheaper LuxI and the LuxIII except for the current they are binned at.

At least when they first came out, (lux3) they handled heat better. The lux1 could be overdriven to 700ma with good success, but after 700ma, like 1 amp, they didn't increase in light like the lux3 did when ran at 1 amp.

"The Luxeon data sheets might be "out of date"."

I have been wondering the same thing. For example some typical lumen figures are quite low and do not represent the actual situation right now. E.g. Lux1 emitter datasheet says that typical lumens is 45... Isn't that R-bin?

-N