I wasn't sure whether to post here or in LED forum, but since it is of most interest to those designing driver circuits I post here.
I had been assuming that the efficacy of current P4 bin Cree XR-E is about 80 lumens/watt. When looking at the spec sheet and doing the math, I was a bit surprised.
notes:
1) the 140mA number was approximated from a graph but should be close, the other numbers were from the spec sheet.
2) voltage is from the spec sheet but this number varies quite a bit from one batch to the next.
It seems to me that there is a great advantage in under-driving multiple emitters.
Any thoughts ?
I had been assuming that the efficacy of current P4 bin Cree XR-E is about 80 lumens/watt. When looking at the spec sheet and doing the math, I was a bit surprised.
Code:
mA Volts Watts Lumens lm/watt
140 3.0 0.42 40 95.2
350 3.3 1.16 80 69.3
700 3.5 2.45 136 55.5
1000 3.7 3.70 176 47.61) the 140mA number was approximated from a graph but should be close, the other numbers were from the spec sheet.
2) voltage is from the spec sheet but this number varies quite a bit from one batch to the next.
It seems to me that there is a great advantage in under-driving multiple emitters.
Code:
mA lumens Volts Watts
5 x 140 200 3.0 2.10
2 X 350 160 3.3 2.31
1 x 700 136 3.5 2.45
