Forward voltage (Vf) binned LEDs...and non Vf binned LEDs?

[Flyback]

The below (example LEDs '1' and '2') demonstrates that Forward voltage binned LEDs are always around twice as much in cost as otherwise equivalent non-forward-voltage binned LEDs.
Given this price difference, why do people use forward voltage binned LEDs?
I mean, LEDs are always put in series (most usually anyway) so forward voltage binning shouldnt matter?



1.....Cree, White, XPEHEW-L1-000-00BE7 = $1.54 (@ 5000 pces on digikey)

XPEHEW family datasheet:-
https://www.electro-tech-online.com/custompdfs/2013/05/XLampXPEHEW.pdf



A cheaper alternative would be:-
2.....Cree, White, MX6AWT-A1-0000-000BE7 = $0.77 (@ 5000 pces on digikey)

MX6AWT datasheet:-
https://www.electro-tech-online.com/custompdfs/2013/05/XLampMX6.pdf




.......................

Page 8 of this following shows the Vf bins...(for XPEHEW LED)
XPEHEW is a member of the xlamp family of leds
https://www.electro-tech-online.com/custompdfs/2013/05/XLampXPBL.pdf

 

[ericgibbs]

Given this price difference, why do people use forward voltage binned LEDs?
I mean, LEDs are always put in series (most usually anyway) so forward voltage binning shouldnt matter?

hi,
I guess by 'binned' you mean batches of known forward voltage drops for the LED's?

Many manufacturers use matched LED's in parallel circuits, where it is important the forward voltage drops are the same.

Also if you use them in series , with a series resistor, its important to know the Vfd of each of the LED's in the series chain.

Example:
if you claimed the light output of your series LED chain is 'X' lumen's, you would have to use SOT [ select on test] series resistors during the manufacturing stage in order to ensure that the current, at a specified operating voltage was the same for every series chain.

E.