Searching the most efficiant warm white LED chip

Oznog

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Well DX's SKU #51989 I got seemed pretty yellowish compared to the #50599 which was more of a bluish white. OK, yeah, the T2-T3 on the Cree datasheet at the "warm white", I see. Maybe I wasn't seeing the color correctly, maybe DX was sending a warm, or at least a neutral, out under the wrong part #- which is easy to see since Cree puts nothing on the LED itself to identify them.
 

Mkala

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Oznog, thank you for your reply.
I am in Europe What is KD/DX ? DX= DealExtreme ? I have not found Warm white Cree chip led on it.

Cooling should not be an issue for my light, comparing to a flash light I can use a huge heatsink to cool it.


Microa, thanks, looks intersting. One good thing is that the voltage is higher and current lower. It is more easy to find AC/DC supplies with low current (350-700mA).
But this chip is more difficult to find, I will see if I can get it.
 

zzonbi

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me neither, but check out cxa2011: far from the wishful lab lm/W, but nice lm/$ (some 3000lm for 15$)... cree is king when it comes to cheap lumens
 

Mkala

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Thank you for this idea !

But -as you say- lumens/w is not very interesting. At nominal drive current, we are about a 70lm/w, but at output I need (about 1500lm) we are already lower at about 60 lm/w.

This weekend I have ordered XM-L module (see above), XM-L alone and XP-E high CRI (> 90) to do some tests :)
 

MWClint

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Mouser.com has the T2 Bin Seoul, 93 CRI, Neutral whites, 4000K 88-91 lm/w
I have been using 20 of these leds all spring to grow tomato plants from seed, indoors.
i'm using 5 leds in series epoxied to an aluminum carpet trim bar(5$ home depot) driven by a surplus 16.6v laptop power supply. each led is seeing ~550mah.
built 4 of these and they have been running 8-12 hours per day. finished building a stone retaining wall raised garden yesterday, and with the
weather warming up, i'll be transplanting them all outdoors.



Mouser Part #: 889-S4218006T2EL
Manufacturer Part #: S42180-06-T2-EL
Manufacturer: Seoul Semiconductor
Description: LED High Power (> 0.5 Watts) Natural White 4000K 3.8W, 88-91lm
 

Mkala

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Thank you for these informations, this one can be intersting too !

The CRI (typical) is very good, but when the CRI is good the efficiency is generally not the best :

For your 4000k / 93 CRI LED, claimed output is 76lm @ 3.3V / 0.35A (=1.15W) => 65lm / w

But we cant have all, rendering should be very good. Do you have pics ?
 

zzonbi

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I stand by the cxa, on paper it's 83lm/W nominal, for 3000K/cri80 :)
But we should compare at equal lm/$: by choosing 50lm/$ drive level you get 100lm/W, if we equalise temperatures too, ie Tj 25C. Anyway thermal resistance is very low, 0.4C/W, so 85C seems overkill.
 

MWClint

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For your 4000k / 93 CRI LED, claimed output is 76lm @ 3.3V / 0.35A (=1.15W) => 65lm / w

hmm, thats an old typo on mouser's site thats been there since they hosted S2 bins.
these are T2 bin which are 88-91lm, which is written on their site, i also verified by calling them and having them check the bin on their packaging.

here's a screen of the leds i'm talking about.
mousertypo.png

but when you click on it, you see the old S2 spec typo. I told them about it..but they havent fixed it yet. :whistle:
 

Mkala

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I finally received my package! The delivery company has lost the first one... After, LED-Tech has re-send it quickly and now I have my LEDs !

led_received_june_2011.jpg


Top left : 3x Cree XM-L T3
Top right : Cree MX 3
Bottom left : Cree XP-E high CRI
Bottom right : Cree XM-L T3

Today, drilled and tapped the heatsink :

xml_heatsink_parts.jpg


xml_heatsink_parts_2.jpg


It is a little too big.. but it is better as a little to small.

All mounted :

xml_heatsink_mounted.jpg


Next, I will do some tests to find the luminous flux I need, and with this choose the operating current.
After this I can chose and design the electronics.

:wave:
drilled%20and%20tapped%20the%20heatsink
drilled%20and%20tapped%20the%20heatsink
 

deadrx7conv

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Too funny with led-tech.de since my shipment was also lost or mis-shipped... They resent them but wish they'd get their 'shipping act' together. My original shipment's tracking number bounced all over Europe for a couple weeks.

Thats a nice simple light build. The bigger the heatsink is, the better!!! Many tend to go too little. But, I would have sanded/lapped/polished the heatsink area before mounting the LED.

Triple XML should produce a ton of light. What drivers, power supply, or batteries are you using?
 

Mkala

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So I am not alone ! Delivred by GLS too ??

Yes I could improve the thermal transfert with a polished heatsink.

I am building a light for the living room, then powered from the mains. The driver for the moment I don't know, I have two choice :

a) Linkswitch-PH from PowerInt (http://www.powerint.com/products/linkswitch-family/linkswitch-ph)
AC/DC IC designed for LED driving. Dimmable with standard triac dimmer. The hard side is to build the transformer...

a) Standard AC/DC PSU, with DC current regulation / dimming. The positive point is I can reduce current in the LEDs to improve efficiency at low illumination needs. But I think the overall efficiency will be lower, even with two good circuit (AC/DC and DC current source / dimmer) at 90% efficiency each, it will result at 81% efficiency.

If you have a driver, an idea, I am listening :) Thanks
 

1215

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Jun 14, 2011
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Possibly meanwell ELN-30-12/15 or HLG-40-12/15 (12 if you want to overdrive to 3.3A) but you may need another XML in the circuit to make it happy with the HLG, however they are pretty nice build quality. Make sure to get the D or B models which have pwm/0-10v dimming (check product sheets for each model).
 

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