# High-power "warm white" LEDs, and US source



## FrontRanger (Nov 17, 2007)

I'm looking for some high-power "warm white" LEDs for use in an interior luminaire. Here, "high-power" means a modern 3W type.

The first issue is to choose the part. It seems that higher color temperatures provide more lumens per Watt, but 7500 K isn't the aesthetic I'm looking for. My best guess is that a color temperature of 3300 to 4000 K might provide a nice compromise. (Yeah, I know 4000 K might be considered "neutral white".) I know of the Cree XR-E and SSC P4. Are there other suitable choices? I recently heard a Lumileds representative say they make something in that range, but I can't seem to find them anywhere.

The second question is where to obtain them. I found this thread from the CPG Marketplace with some warm white U-bin P4s, but they're sold out:
http://www.cpfmarketplace.com/mp/showthread.php?t=162393
And I've found the "warm white" color binned versions of XR-Es on two Australian sites. Does anyone know of a US source for any of the suitable parts? I do care about shipping time and price, since I may end up buying many if my prototype turns out well.

Thank you.


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## jtr1962 (Nov 17, 2007)

Future Electronics has the Rebels in both neutral white (4100K) and warm white (3000K), and each in several flux bins:

Neutral White

Warm White

Based on what you stated, neutral white is probably closer to what you're looking for. Like you, I personally feel ~4000K has the most versatility for general lighting. Not too cool so as to bother those used to incandescent, but not so warm as to annoy those who prefer lighting closer to daylight.


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## FrontRanger (Nov 17, 2007)

Thanks, jtr1962. Those look suitable. My design uses six emitters, and for my first pass I'll try using four neutral whites with two warm whites, in hopes of achieving a good balance between flux and color.


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## brickbat (Nov 18, 2007)

I like that idea. Not sure what you're trying to light, but you might think about a driver that allows varying the drive to the 2 groups so that you could dial the color temp in to what you like...

Assuming you're comfortable soldering them, you might want to look at the Luxeon K2 LEDs. Future has stock in WW, Neutral and CW.


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## FrontRanger (Nov 19, 2007)

brickbat said:


> I like that idea. Not sure what you're trying to light, but you might think about a driver that allows varying the drive to the 2 groups so that you could dial the color temp in to what you like...


 
I'm building a wall-mounted light fixture for my living room. The LEDs will be aimed primarily upwards, but at an angle of ~20 degrees from the horizontal, washing the ceiling, so total flux (lumens) is at a premium. I thought about varying the current in groups as you describe, but that doesn't give me independent control of flux and CCT. So my preferred solution is to vary the number of LEDs of different CCTs and run them all at full current. This is less flexible in terms of CCT, but I don't think I'll be too sensitive to that, and it does provide maximum flux.



brickbat said:


> Assuming you're comfortable soldering them, you might want to look at the Luxeon K2 LEDs. Future has stock in WW, Neutral and CW.


 
Why the K2 over the Rebel? I've looked at the K2 data sheet before, and I seem to recall that its flux ratings are much less than the Rebel. Is there some other advantage to the K2?

Thanks,
Stephen


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## brickbat (Nov 19, 2007)

FrontRanger said:


> ...Why the K2 over the Rebel? ...



Future does not show stock of the Rebel in WW. They have the K2 in WW, U bin. Let me know if you find stock on a WW Rebel...


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## PhotonWrangler (Nov 19, 2007)

Have you considered the new VIOLED from G-E? You can order directly from their factory.


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## brickbat (Nov 19, 2007)

PhotonWrangler said:


> You can order directly from their factory.



Have you asked? As a hobbyist wanting a few dozen, it'd be pretty unusual for a semiconductor manufacturer to want to fuss around with this transaction.


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## PhotonWrangler (Nov 19, 2007)

PM sent. Short answer, yes.


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## FrontRanger (Nov 19, 2007)

brickbat said:


> Future does not show stock of the Rebel in WW. They have the K2 in WW, U bin. Let me know if you find stock on a WW Rebel...


 
Hi Jim,

If you go to the "Warm White" link provided by *jtr1962* upthread, Future Electronics lists the warm white Rebels, under part numbers LXML-PWW1-0040 through *-0060. Under the "Stock" heading they say to call for availability. I think you're probably right that they're out, because I couldn't find them in stock anywhere else on Google, but did you already call?

Thanks,
Stephen


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## made in china (Nov 20, 2007)

PhotonWrangler said:


> Have you considered the new VIOLED from G-E? You can order directly from their factory.



Anyone have any more info on these? Like price? I just downloaded the PDF datasheet, looks very interesting.


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## jtr1962 (Nov 20, 2007)

made in china said:


> Anyone have any more info on these? Like price? I just downloaded the PDF datasheet, looks very interesting.


Link to datasheet.

I was excited about these until I read that the typical flux bins for the 4 watts are I, J, and K. Even the K bin is only a maximum of 233 lumens. The I bin can be as little as 119. I'd guess typical is right in the middle at ~175. Granted, these have a few good selling points such as consistent color temperature and a larger source size. I'm not surprised at the lower efficiency. UV plus phosphor LEDs are inherently less efficient in the phosphor conversion process.

Now if they can get these to at least 300 lumens minimum at 4 watts, better yet 400, they'll start to sound very interesting. I suppose that's only a matter of time. More money has been poured into increasing the efficiency of 450-470 nm LEDs rather than 405 nm.


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## FrontRanger (Nov 20, 2007)

The last page of the datasheet states that there's a minimum order size of 10, and that an additional handling charge applies for it.

Their square boards use Molex connectors. If you don't want to spend money on the mating connectors (and possibly a crimper), it appears it would take a lot more work and soldering skill than working with a standard star. This aspect, and the comparitively modest flux, make me not that enthused about them. Still, it is nice to know all the options, so thanks for posting about it, PhotonWrangler. And you never know what they may offer in the future.


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## FrontRanger (Nov 20, 2007)

FrontRanger said:


> Hi Jim,
> 
> If you go to the "Warm White" link provided by *jtr1962* upthread, Future Electronics lists the warm white Rebels, under part numbers LXML-PWW1-0040 through *-0060. Under the "Stock" heading they say to call for availability. I think you're probably right that they're out, because I couldn't find them in stock anywhere else on Google, but did you already call?
> 
> ...


 
I called Future Electronics. They do NOT have them in stock, but thought they might in a few days.


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## Erasmus (Nov 21, 2007)

I was also on the quest for good (e.g. SSC, Cree. Rebel) warm white LEDs and I can finaly obtain them at a reasonable price. More info @ http://www.cpfmarketplace.com/mp/showthread.php?p=2088166#post2088166


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## made in china (Nov 21, 2007)

FrontRanger said:


> Their square boards use Molex connectors. If you don't want to spend money on the mating connectors (and possibly a crimper), it appears it would take a lot more work and soldering skill than working with a standard star.



The connector they use is a highly standard, common part. It would cost you, oh say about $0.50 or so in parts to make the mating connector. You don't really need the expensive tool, you can just use needle nose pliers and a little solder.

The nice things about these VIOLED's that I can see at first glance:

The form factor and that connector are great for utilizing in OEM designs. Very easily replaced without any skills required.

The large dome keeps the phosphor off of the hot die. I think this one one of the reasons they can keep the color temp so tight for so long.

The large dome reduces the intense point source of the light, in effect reducing glare a bit. Again, nice for OEM designs geared toward desk lamps, general lighting, etc. Not nice for your flashlight!

The life span is excellent. 70% output maintainence after 50,000 hours is great for a white emitter.


I like them. Of course if they are expensive I may change my mind depending on price. These looks like a promising new approach to white LED light.


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## FrontRanger (Nov 23, 2007)

made in china said:


> The connector they use is a highly standard, common part. It would cost you, oh say about $0.50 or so in parts to make the mating connector. You don't really need the expensive tool, you can just use needle nose pliers and a little solder.


 
I'm glad to hear that they're easy to get. My impression was simply that having a connector only benefits mass production during assembly, since replacement is not likely.



made in china said:


> The large dome reduces the intense point source of the light, in effect reducing glare a bit. Again, nice for OEM designs geared toward desk lamps, general lighting, etc.


 
That's something I had not noticed. Thanks for pointing that out.


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## PhotonWrangler (Nov 23, 2007)

When I visited their factory I watched one of their lab managers showing us the difference in color rendition as he placed different phosphor domes over the same chip. Yes, the dome allows for a significant amount of separation between the phosphor and the chip.


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## laserblue (Nov 26, 2007)

ah ic.. i think it is compared to the color of the CIE chart to gauge the whiteness of the LED output.


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