Tobias Bossert
Newly Enlightened
I made a mistake by comparing XT-E S2 instead of XT-E R5. S2 isn't availlable jet. I corrected the Excel sheet now.
Al statements in this thread which must be altered are marked red/bold now!
Which one is the best performing led at the moment?
This frequently asked question cannot be answered without specification of what is the meaning of "best".
For this post I will ignore things like die size, angular pattern, color rendition etc and focus on maximum flux at given electrical drive conditions.
If you drive a led with a linear driver, you are interested to get as much flux as possible from the drive current. The forward voltage of the led (and therefore the led power too) is of no interest, as long as it remains below supply voltage. In this application the quantity 'Lumens_per_Amps' counts.
If you drive a led with a buck or a boost driver, than you are not interested in the current directly, you would like to get as much flux as possible from power consumption. In that application the quantity 'Lumens_per_Watts' counts.
I used Cree PCT (product characterization tool) with the setting TSP = 25° to compare XR-E R2, XP-E R4, XB-D R5, XP-G S2, XT-E R5 and XM-L U2 with respect to lm/A and lm/W.
I put all data into an Excel sheet. The result is clear:
For linear driver applications up to 400 mA XT-E R5 or XB-D R5 is the winner. For currents above this level, XM-L U2 is the best performing led.
For buck and boost driver applications XT-E R5 or XB-D R5 is best up to led currents of 220 mA, above that, XM-L U2 is better.
The limits are different because XM-L has a lower forward voltage and thus a lower power consumption compared to XT-E at the same current.
XT-E R5 and XB-D R5 seam to have their best efficiency below 100 mA, because both values lm/A and lm/W still show a significant slope at the lower end of the range specified by Cree PCT. At 100 mA the luminous yields are 510 to 524 lm/A and 182 to 184 lm/W.
XM-L U2 seams to have its best efficacy 165 lm/W at about 150 mA or just below that value, because the slope of this quantity is nearly flat at the lower end of the range specified by PCT. The best yield in terms of flux per current is reached at about 200 mA (443 lm/A).
Unfortunately Cree PCT doesn't support the new led generation XP-E2, XP-G2 and XM-L2. Those should be better at least at high current levels. The datasheets don't allow to extract reliable values.
Does anyone can provide data for XP-E2, XP-G2 and XM-L2 as well?
Al statements in this thread which must be altered are marked red/bold now!
Which one is the best performing led at the moment?
This frequently asked question cannot be answered without specification of what is the meaning of "best".
For this post I will ignore things like die size, angular pattern, color rendition etc and focus on maximum flux at given electrical drive conditions.
If you drive a led with a linear driver, you are interested to get as much flux as possible from the drive current. The forward voltage of the led (and therefore the led power too) is of no interest, as long as it remains below supply voltage. In this application the quantity 'Lumens_per_Amps' counts.
If you drive a led with a buck or a boost driver, than you are not interested in the current directly, you would like to get as much flux as possible from power consumption. In that application the quantity 'Lumens_per_Watts' counts.
I used Cree PCT (product characterization tool) with the setting TSP = 25° to compare XR-E R2, XP-E R4, XB-D R5, XP-G S2, XT-E R5 and XM-L U2 with respect to lm/A and lm/W.
I put all data into an Excel sheet. The result is clear:
For linear driver applications up to 400 mA XT-E R5 or XB-D R5 is the winner. For currents above this level, XM-L U2 is the best performing led.
For buck and boost driver applications XT-E R5 or XB-D R5 is best up to led currents of 220 mA, above that, XM-L U2 is better.
The limits are different because XM-L has a lower forward voltage and thus a lower power consumption compared to XT-E at the same current.
XT-E R5 and XB-D R5 seam to have their best efficiency below 100 mA, because both values lm/A and lm/W still show a significant slope at the lower end of the range specified by Cree PCT. At 100 mA the luminous yields are 510 to 524 lm/A and 182 to 184 lm/W.
XM-L U2 seams to have its best efficacy 165 lm/W at about 150 mA or just below that value, because the slope of this quantity is nearly flat at the lower end of the range specified by PCT. The best yield in terms of flux per current is reached at about 200 mA (443 lm/A).
Unfortunately Cree PCT doesn't support the new led generation XP-E2, XP-G2 and XM-L2. Those should be better at least at high current levels. The datasheets don't allow to extract reliable values.
Does anyone can provide data for XP-E2, XP-G2 and XM-L2 as well?
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