XM-L2 brighter due to higher forward voltage?

Looking at the XM-L vs. the XM-L2 die what differences do you see? Your answer lies in the answer to that question.

Why hello new and different material

Nope, try again.

Aside from the SiC tech, I suppose the reduction of an internal bond wire could lead to higher bond-wire resistance… That would kick Vf up a bit…

I wouldn’t doubt if going to 2 bond wires vs. 3 did cause the Vf to go up, but I am more talking about what increased brightness as opposed to what increased Vf.

What can you see on top of the XM-L die that you can’t see on the XM-L2?

Well, I do agree that the XM-L2 is more efficient, but there is a positive correlation between Vf and lumens as well, right?

No, there isn’t. XP-G2 is a prime example. It has higher lumens per watt and a lower Vf than the original XP-G. Vf has correlations to current and to temperature.

Ah, I was answering a question that you hadn’t asked :slight_smile:

Truthfully, I don’t have an XM-L2 handy at the moment, and I can’t think of anything off the top of my head.

Good example, thanks.

@bose: the strips of wires(?) over the XM-L block the light?

New and improved, extra fluffy phosphor?

BINGO!

Not the only thing but a major part of the increase, the single biggest.

Yay! What were they used for? Current spreaders?

Exactly.

:smiley: :smiley: :smiley:

So that’s what improved the tint! Shoulda known…fluffy=warmth

Weeding out correlation from causality is always a problem.

On the XM-L2, what is the function of the wire on the right of the dome that is not touching the phosphor layer?

Willing to bet it’s the ESD protection, I actually don’t know so this is just a guess.

So there is more than one way to take advantage of the increased efficiency. One is to use a boost buck driver and run the xml2 at 3A+. Another would be to run the xml2 at a lower current(2.6-2.7A) and realize the efficiency gain in run time keeping output more constant. Thus would allow continued use of 7135 based drivers without loss of time in regulation. Obvious stuff but might as well say it.