Driving LEDs at 0.02mA - Nichia GS disappoints

[balou]

I'm making some Paklite clones, and I use a 270kOhm resistor for the find-me-at-night mode. The difference between a DX "22'000mcd" LED from a Fauxton vs a Nichia GS was very interesting.
But see for yourself:

edit:

 

[jtr1962]

The GS has a larger die, so the current density will be lower at any given current level. With all LEDs, there comes a point where a lower current density results in less efficiency. Apparently this is what's happening here.

 

[paulr]

hmm, DS might be better?

 

[balou]

The GS has a larger die, so the current density will be lower at any given current level. With all LEDs, there comes a point where a lower current density results in less efficiency. Apparently this is what's happening here.

Thanks for the explanation.

Paulr: Problem is, Nichia DS have become unobtainium.

Btw: The capability of a XR-E Q5 to light up a room at 5-6mA is fantastic.

edit: and just another tidbit I wanted to add: Vf variance with Nichia GS LEDs is surprisingly low. Sample of 10 LEDs: at 5mA between 2.70V (1 pcs) and 2.74V (1 pcs), the other 8 pieces between 2.71 and 2.72V. At 50mA, the two outliers have 3.30V and 3.45V resp. A random other GS had 3.34 at 50mA

 

[paulr]

Paulr: Problem is, Nichia DS have become unobtainium.

store.nichia.com has them.

 

[fyrstormer]

Thanks for the explanation.

Paulr: Problem is, Nichia DS have become unobtainium.

Btw: The capability of a XR-E Q5 to light up a room at 5-6mA is fantastic.

edit: and just another tidbit I wanted to add: Vf variance with Nichia GS LEDs is surprisingly low. Sample of 10 LEDs: at 5mA between 2.70V (1 pcs) and 2.74V (1 pcs), the other 8 pieces between 2.71 and 2.72V. At 50mA, the two outliers have 3.30V and 3.45V resp. A random other GS had 3.34 at 50mA

LED-TECH.de sells DS' still.

 

[R@ndom]

Don't forget about the major VF difference.