3 and 4 leads on Cree XR-E LED ?

[glire]

I recently purchased some "well known" CR123 lights. Two of them have Cree LED and I noticed they have 4 leads on the die. My other Cree ligths have 3 leads (L0D-CE, JeyBeam CL-E, also some 230V bulbs).
So, has there been a recent change in the Cree LED manufacturing ? Why, what are the advantages ?
Thanks, and sorry if this has been already discussed (couldn't find a thread about it).

 

[DonShock]

I'm not sure if it just appies to these two types, but my P4 Crees have three bond wires on the die and my Q2 Crees have four bond wires.

 

[DonShock]

Glire: I did some more investigating and think I found a way to tell the difference between P3, P4, and Q2 Crees, see this thread for the details.

 

[glire]

Thanks.
And interesting, but I doubt. My Cree LEDs with 4 wire bonds came mounted in "cheap" (and recent) CR123 lights. Those lights are advertised as having P4 Cree LEDs and they sell for about $16 to 20. The only thing I'm sure: they're amazingly bright.

To me, those differences are an evolution in the manufacturing process. The binning is the result of a sort after manufacturing, unless the manufacturer found a way to make a precise binning.

Any one "who knows" could enlighten us ?

 

[IsaacHayes]

They are bond wires that supply the current from the pads to the die. Cree added another to lower Vf of the LEDs, essentially increasing efficiency. This helps a lot as you approach higher drive currents since there is more losses in the thin wire with more power. So lower VF = longer running lights.

EDIT
Glire you are right, the added bond wire is what they are doing on all leds now. That means there could be any bin that they produce with the 4 wires now.

 

[Erasmus]

Thanks.
And interesting, but I doubt. My Cree LEDs with 4 wire bonds came mounted in "cheap" (and recent) CR123 lights. Those lights are advertised as having P4 Cree LEDs and they sell for about $16 to 20. The only thing I'm sure: they're amazingly bright.

To me, those differences are an evolution in the manufacturing process. The binning is the result of a sort after manufacturing, unless the manufacturer found a way to make a precise binning.

Any one "who knows" could enlighten us ?

Even if the die has the same performance, a lower Vf can make a whole difference in flashlights with boost circuits. I have recently used a P4/WH from my groupbuy from November 06 in a standard L0P. I dropped in a 'standard' one (around 3.25 V @ 350 mA) and then an exceptional one (3.03 V @ 350 mA) and it made a huge difference! If you use single CR123 lights (cheap lights with probably drivers which only raise the voltage and are not constant current drivers) and they look amazingly bright it's just because the low Vf and probably not because they accidently dropped a Q-bin into it

EDIT : I just checked the graphs with test results from Jtr1962. It seems to be a 'normal' XR-E P4/WH with 3.25V@350 mA. That same led was driven at only 150 mA when Vf is 3.04 V. So when driven at 3.04 V you see a huge difference with my exceptional low Vf XR-E : 41 lumens (standard XR-E) vs 85 lumens!

Hmm maybe my explanation is a little confusing but somehow it makes sense

 

[nikon]

I was at Lowe's today and bought one of the new Energizer Hard Case Inspection lights. I couldn't find the name "Cree" anywhere on the package and the LED in this light, which looks like a Cree, has only two wires. Could this possibly be a clone of the Cree?

 

[Gunner12]

I think the lower Bin Crees still only have two bond wires. I think the P2 is one of them. Either that or they are using older Cree LEDs.

 

[IsaacHayes]

Looks Cree-isque. It may be the older non-XR-E model??

 

[SteveDavis]

The two wire Cree you show is most likely an XR-C. The die appears to be smaller than an XR-E die, and the pattern on it looks like an XR-C as well.

Cree has been modifying their manufacturing processes in many products, but their rationale is close to the vest. I have not heard them say anything about Vf reduction (nor does that really make sense to me, as the resistive component is so small). XR-E's have officially varied from 3-4V Vf at 350mA as far back as I know. Cree has claimed no performance difference of any kind for any manufacturing variant using the same part number. I expect given a large enough sample size, you will see 3 and 4 wire bond versions of the same bin, likely in all colors.