# Straw hat High power LED?



## footprintz (Sep 22, 2009)

Hello friends. I need to know a thing.. i have asked many manufacturer. is there any LED which is 3W and in Straw hat LED (8mm/0.5W) shape head and mount on PCB? if any of LED available it will be very helpful for me. Thanks


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## saabluster (Sep 22, 2009)

footprintz said:


> Hello friends. I need to know a thing.. i have asked many manufacturer. is there any LED which is 3W and in Straw hat LED (8mm/0.5W) shape head and mount on PCB? if any of LED available it will be very helpful for me. Thanks


Maybe "Straw hat LED" is a term used there but I've never heard of it. Care to post a picture of what you are looking for?


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## Patriot (Sep 22, 2009)

Hmm, it looks like a google translation error to me.


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## evilc66 (Sep 22, 2009)

Straw hat refers to a dome shape (don't ask me what the relation is). It's usually for high angle LEDs (almost flat dome). There are no manufacturers of 8mm straw hat LEDs over 1/2W. The package simply cannot handle the heat. I've seen 1W 10mm, but I wouldn't expect them to last very long.


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## bshanahan14rulz (Sep 22, 2009)

I've seen 5-chip strawhats on e-auction site, but no real high-power ones.


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## footprintz (Sep 22, 2009)

ok, i have ordered for 1W,Straw hat shaped 80 Lumen LED to a manufacturer from China. i samples are ready and will reach me in 5 days. I will post Datasheet and images also.


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## lolzertank (Sep 22, 2009)

8mm LEDs, also known as "straw hat" LEDs, don't have enough heatsinking for anything above 100ma which is already pushing the limits of the package. 

Take a look at this thread. https://www.candlepowerforums.com/threads/171943

The LEDs are the same, just mounted on a little PCB (not MCPCB) that does nothing to conduct heat.


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## JohnR66 (Sep 23, 2009)

footprintz said:


> ok, i have ordered for 1W,Straw hat shaped 80 Lumen LED to a manufacturer from China. i samples are ready and will reach me in 5 days. I will post Datasheet and images also.



Do you have a picture of these to post? I tested a straw hat multi chip LED. It was supposed to be .5 watt which means a drive current of around 140ma. I drove them at ONLY 100ma for 192 hours (8 days). The LED faded severely to a feeble purple showing burn spots over the dies. The worst LED I have ever tested. I tested a another 10mm LED and it did better but still faded after 192 hours.

From this, my criteria for driving these these medium power multi chip LEDs: 20ma x no. of chips x .5, so a 4 chip LED would be 40ma max for good lifetime. This is assuming that they are using the 20ma die found in 5mm LEDs.

I would recommend using a Cree XP-E. This is a mini power LED with essentially low dome beam characteristics. It would need heat sinked, of course.


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