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Lumens/Watt in LEDs when forward current is very low.?

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treez

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Page 10, top graph, (datasheet below)…what happens to the graph below 50mA?....is it just like a continuation of the same general shallow curvature?
The graph concerned shows luminous flux vs current for a LED
If you don’t know the answer, then intuitively, do you suppose that lumens/Watt gets ridiculously low for very low forward currents in LEDs?

Wicop Z8Y11 LED
http://www.seoulsemicon.com/upload2/2019055_A_Specification_Y11_Rev9.3_190426.pdf

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Also, is the lumens per watt of this led (for the W4 variety on top of page 3) equal to 171 lumens per watt? ...ie { 77 lumens / (3V*0.15A) }

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Ever tried to sort leds on lumens per watt (highest to lowest) in digikey?..its impossible...you just get loads of obselete leds......do you know how to do it?
 
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FvM

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What's very low current for you? 1 mA? 1 uA? I suppose linearity at reasonable low currents.

I don't understand your problem with Digikey parametric search. You can narrow the search to active products, isn't it?
 
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treez

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Thanks, i mean for current from 0 to 50mA in the above mentioned example (page 10, top graph)
 

betwixt

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Intuitively I would say it continues down to zero almost linearly. I would guess the graph doesn't go lower simply because it is outside the scope of normal usage, just like car fuel usage is specified at average driving speed rather than at a snails pace.
I have LED lighting at home with LEDs rated at 700mA (although I run then at 500mA) but overnight I dim them by limiting the current to 1mA, they give just enough brightness to see by.

If you need more accurate control at very low brightness, I would suggest PWM dimming would be more predictable.

Brian.
 

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