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Led question

The white 'phosphored' leds are maturing products and, from the major manufacturers at least, now have decently predictable lifespans.

Fairly new to the market are the 5mm (T13/4) coloured (Red,Yellow etc) 'phosphored' leds and I am wondering if the teething problems of the white leds will be repeated for these coloured devices or whether lessons have been learnt.

Most white development is (and was) toward upward of 1W devices in the manufacturers various proprietry packages but I wonder if there still are pdegradation roblems with 5mm 'phosphored' led packages and/or whether these new 'coloured' phosphors themselves have know degradation characteristics.

The phophored yellows in particular appear to have superior efficacies to the normal PN junction devices.

Reply to
RHRRC
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Early , couple of years back, pink phosphor LEDs, think was organic phosphors, had lifetimes in hours, after 24 they would have faded to a rather pretty pastel blue.

Having had some, er, problems with `warm` white LEDs would think that there is more than one phosphor mix that works, and probably only one that lasts... Remember the Taiwanese electrolytic capacitor disaster.

Nichia`s orginal business is phosphors and would expect them to be one of the better performers, depends on client expectations and budget

Adam

Reply to
Adam Aglionby

There's good information over on candlepowerforums.com about LED lifespan. The 5mm white LED diven at max current (20ma typ) are only going to last a few thousand hours before the light degrades to 50%. If I were going to design a device using these LEDs and desired good run time, I'd use more LEDs and drive them in the 10-15ma range or consider a power LED. OTOH, if I was going to use them in a flashlight where the usage is very limited, I'd over drive them a bit because a life span of 500 hours is good enough.

Drive current and keeping them cool seem to be the ingredients to longer life. John

Reply to
JohnR66

Adam Aglionby wrote in news:48749410-73ec-40ff-b731- snipped-for-privacy@c36g2000prc.googlegroups.com:

Are they still problematic? If using white LEDs, should onme stick with the non-"warm-white"?

Thanks!

Reply to
Kris Krieger

h the

It is a bit like early whites where the difference between a Far Eastern `commodity` LED and top line Nichia/Toyoda/Cree was like day and night, now best of the Far Eastern whites are pretty comparable to a big brand part.

Warm White is still very much a question of life testing before buying or deploying quantity, and be aware of the miserably lower efficiency of them, even from big names.

Adam

Reply to
Adam Aglionby

Adam Aglionby wrote in news:c13ffc2e-3b5f-416d-9935- snipped-for-privacy@v28g2000hsv.googlegroups.com:

OK, that exactly answers it, Thanks!

- Kris

Reply to
Kris Krieger

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