Is a Luxeon at 50ma brighter than a Nichia?

Can anyone tell me if a Luxeon driven at 50ma would be brighter than a Nichia running at 30ma?

(Edited for sanity......)

If I can recall my semiconductor physics, the basic principle is
One electron equals One photon.

So if the two LEDs have the same efficiency (which they basically do) I would expect them to be very close in brightness.
---Marc

So if they were both driven at 30ma they would both be about the same?

Yes. They should be about the same. Why would you want to run a Luxeon so low? It would be like buying a race car and only driving it 5 mph in a parking lot.
(Now let me fix my typo above where I answered the wrong question.......---Marc

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zmoz said:
So if they were both driven at 30ma they would both be about the same?

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There is much variation among individual leds but you can expect a typical 1W white luxeon to be much brighter at 30mA than a typical 5mm white Nichia at 30mA.
Edit: I am assuming here that by "brightness" you really mean total light output and not intensity. One other thing, in addition to more output at 30mA the Luxeon would [typically] require less power.

Doug---Please explain. If we assume that the Vf's are the same why would the LS be significantly brighter?

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MicroE said:
Doug---Please explain. If we assume that the Vf's are the same why would the LS be significantly brighter?

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Sure. These [white, blue, and other InGaN] LEDs are more efficient at low current densities compared to high current densities. Because the Luxeon has a large die relative to the Nichia, at a given current the Luxeon will be operating at a much lower current density and thus be more efficient. BTW, Vf is also a function of current density and thus at the same current the Luxeon can be expected to have a lower Vf, hence my remark above about requiring less power.

[ QUOTE ]
MicroE said:
Yes. They should be about the same. Why would you want to run a Luxeon so low? It would be like buying a race car and only driving it 5 mph in a parking lot.
(Now let me fix my typo above where I answered the wrong question.......---Marc


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Just wondering...and thinking about a light with varying amounts of output. Don't worry...the only luxeon I have right now is burning at about 600ma. /ubbthreads/images/graemlins/grin.gif

Give Mr. Doug his due.
I just went into the basement and hooked up a green LS and a green Nichia in series and drove them at 50mA.
The LS is slightly brighter. Not by leaps and bounds, but the difference is noticeable in a side-by-side comparison.---Marc

Excellent! Reasoned theoretic exposition followed by empirical testing!

Thanks, Doug and Micro! /ubbthreads/images/graemlins/grin.gif

And of course with the Nicha being heavily overdriven- what did it do over time? (should be less than 10 seconds)