Lumileds announce new K2

See the website!
Only thing is, they quote 160Lm at 1000mA and bang on about the ability to be driven at 1 amp continuous - who cares? - The R2 bin crees achieve this at 160 Lm at 550mA. At 1A it will achieve 250Lm. Even if you doubt crees abaility to live constantly at 1A, it doesn't matter as you can achieve the same output at lower current.
When you look at the datasheet, there are higher bins availble - ones that achieve 200Lm at 1000mA - why don't they shout about those? We know that higher flux bins have been available (see Rebel).
I have always supported Lumileds in threads when it seemed that the pro-cree'ers were out in force, but Lumileds do seem to shoot themselves in the foot with partial releases and datasheets that say 'we are the best' with data that indicates that they actually loose out in the real world. Only if they launched the 200 bin now and you drive it at 1.5A would you see an advantage.
This is a quick rant on my lunchtime and not the best put together discussion, but I am waiting for somthing from Lumileds that does not appear to be surfacing....

Another thing - just looked at the data sheet and the output at 1000ma looks about 2.22 x that at 350mA - same as cree. What happened to that anti- droop technology that was going to be incorporated by Q3 of this year (July-september)? Has that found its way into another product??

The "K2 with TFFC" may not be on par with the best Crees but still seems pretty interesting to me. Remember 200lm at 1000mA is the minimum spec (for the 0200 product).

Typical flux:

95lm @ 350mA
170lm @ 700mA
275lm @ 1500mA

This still makes it the brightest single die LED available and is not that far off the Cree and SSC LEDs at lower drive currents. I wonder what happened to the 500lm LED that they achieved in the lab? Hopefully it won't be long before we see one of those.

I see they're also offering a star base

Oh yeah, well spotted BTW. I think you're the first.

We've known these have been coming for months (I reviewed a pre-production sample here: https://www.candlepowerforums.com/threads/171365)

Lumileds has been dragging their asses getting anything new out, it's about bloody time we see some kind of movement from them.

One interesting thing is the 5.5C/W thermal resistance, which is very good, which means this part could be quite suitable for high current or high operating temperatures.

Future only has the 160 and 180s listed, but both are in stock - at $5.12 and $5.60 each respectively.

It's a shame Lumileds isn't more aggressive at getting high brightness parts out, but the lack of available 200 and 220/240 parts mirrors the lack of availability of 90 and 100 lumen rebels - the demand for 100 lumen rebels is so great that I can see all high bin dies going to those lines instead.

Evan, do you think that it would be worth it to start buying K2s (the new TFFC obviously) since I do not have anything better than a U-bin K2 any way? These look promising but I can't say if these will be better than take 1 of the K2.

Really depends on what you're doing. If you're looking for a direct drop in, it would be a reasonably nice upgrade.

What kind of application are you talking about?

Drop in for my junior Luxeon which is still running a U bin K2. Also possibly using them in home lighting on 6x arrays.

Lots of factors to consider, even for both cases

For the first case, You could use a Seoul P4 which has a very similar package as a K2, would be a bit brighter, but might not focus as tightly due to the P4 having a slightly larger source volume (even though the beam profile is the same). However, one thing to consider with the P4 is that the slug is connected to the positive power lead, and if you don't isolate the slug of the Seoul properly, you could create a short.

Using an XR-E is also an option, but packaging and beam profile differences may be significant enough to render it not a viable option.


For home lighting, beam profile and lumen/$ are likely the more dominant factors to consider. It may be a matter of personal taste which one you choose.

In both scenarios, cost and availablility are also factors to consider.

So like with most things, there is no one easy answer. Choosing one of the new K2s to put in your jr Luxeon is an easy upgrade option, but might not be as bright as it could be with competing LEDs. Depends on how much you want to experiement to see which could be the optimal solution.

monkeyboy said:

Typical flux:

95lm @ 350mA
170lm @ 700mA
275lm @ 1500mA

This still makes it the brightest single die LED available and is not that far off the Cree and SSC LEDs at lower drive currents.

Click to expand...

I'm sorry but this K2 sucks. The R2 cree is doing 275 lumens at 1000mA. And thats before you overdrive it(which it can handle no problem).

saabluster said:

I'm sorry but this K2 sucks. The R2 cree is doing 275 lumens at 1000mA. And thats before you overdrive it(which it can handle no problem).

Click to expand...

Wow. That's such an in depth and detailed analysis of the situation. Guess there's no reason whatsoever for anyone anywhere anytime to use one of these in any scenario. Period.

Those new K2 probably have the best lumen/$ ratio although I didn't really do any calculation.

Evan,
Am I correct in my assumption that the 'New' K2 should be a pretty good mod to an existing Lux III setup. No machining of reflector needed.

I can't guarantee that. I haven't done extensive comparisons between the old/new K2 and a Lux III in terms of die height.

I could do that later today - attempt to get some pictures of the 3 LEDs side by side to compare die heights

saabluster said:

I'm sorry but this K2 sucks. The R2 cree is doing 275 lumens at 1000mA. And thats before you overdrive it(which it can handle no problem).

Click to expand...

Not a chance that the R2 will do 275lm @ 1000mA and however much the cree can be overdriven, the K2 can be overdriven more with its higher junction temperature

monkeyboy said:

Not a chance that the R2 will do 275lm @ 1000mA and however much the cree can be overdriven, the K2 can be overdriven more with its higher junction temperature

Click to expand...

I have to say a 5.5º thermal resistance plus a 185ºC Tj is quite impressive, but there might be more to it than that. For example the pad size - in which Cree has an advantage -, bond wires, die composition and the so called "droopiness" factor. I don't think we'll know for sure until someone runs full battery of tests on both under real world conditions.

Does anyone get tired of the knee jerk reactions?

Cree:
- More efficient (obviously)
- Isolated package (so much nicer to use)

K2:
- Wide lambertian beam pattern which is better for reflectors
- More even phosphor coating (which can be nice)
- Better thermal (but offset by lower efficiency)

The Cree can be overdriven for "short" periods of time...fine for flashlights, but not in the real world where things need to last. They only rate the life at a low die temp. In long life applications (my day job), that becomes an issue.

As promised, die height comparisons:

Lux III vs. Original K2:


And Lux III vs. TFFC K2:



As you can see, even the original K2 isn't a direct replacement since the die is a bit lower. The new TFFC K2's die is even a bit lower.

Technically with the thin film more photons can escape the die therefore less heat is generated inside the phosphor coat but it is so thin that I wonder if we should start to worry about degradation and phosphor life.

I'm not overly excited about this. It has nothing to do with the somewhat lower output relative to a Cree. Rather, it has everything to do with Lumiled's spotty track record of actually delivering product. The Rebel-100s actually seemed very nice, were competitive with Cree in terms of output, and I think the color consistency was better. They beat Cree hands down on price. Only problem is they're not available, at least for now. The new K2 might be worth a look in certain situations where lumens per dollar or perhaps tint consistency count for more than sheer efficiency. However, if it's not consistently available I wouldn't use it in a product.

The 160s and 180s are available today (I ordered a few for evaluation).