test current efficiency?

[jason 77]

I was wondering when a LED company puts the lumens output at their "test" current on their data sheets whether that is when the LED is at it's most efficient? Like say they say that at 700ma the led puts out 460 lumens, but later on down in the data sheet they say the maximum current is 1500ma. I am not very good at reading the graphs and such stuff on data sheets so if anyone can help me understand them that would be great?

 

[Ragiska]

no, the test current for most high power emitters is 350mA, which is NOT the most efficient current. 350mA is chosen for two main reasons

1) it was once approximately 1watt for white emitters (it's less than 1W now)

2) the second derivative of the flux vs I curve is close to zero at that point

peak efficacy is usually between 15-50mA for high power white emitters