Nichia 5mm max overdrive?

[swamp40]

If I wanted to run an S-ranked Nichia NSPW500BS for only 1 hour, how much current could I run thru it?

It would be a single use application, thrown away after 1 hour, and I'm willing to moderately heatsink it.

It would be driven with a zetex zxsc100.

Does anyone have any experience of the maximum overdrive capabilities of these LEDs?

 

[McGizmo]

Snakebite as I recall did a test with a penny soldered to the cathode lead and he had some major current running through the LED. I think it lasted a day or more. Probably in the archives but good luck! /ubbthreads/images/graemlins/grin.gif

- Don

 

[Rothrandir]

i'd be very interested in hearing what this is to be used for! /ubbthreads/images/graemlins/eek.gif

 

[Doug S]

[ QUOTE ]
brockrobinson said:
If I wanted to run an S-ranked Nichia NSPW500BS for only 1 hour, how much current could I run thru it?

It would be a single use application, thrown away after 1 hour, and I'm willing to moderately heatsink it.

It would be driven with a zetex zxsc100.

Does anyone have any experience of the maximum overdrive capabilities of these LEDs?



[/ QUOTE ]

As has been implied already, the maximum current for a 1 hour life expectancy will depend upon heatsinking. Be aware that this maximum current will be likely to be greater than the current at which you would get maximum light output if this matters.

 

[swamp40]

I wish I could tell you, but you'll just have to use your imagination for now.

We're quoting a job for a customer of ours, and bound by a non-disclosure.

I usually design stuff within the datasheet limits, but there's no way to do what they need and stay within the specs.


Which brings me here, to seek assistance from the renegade modders, who have no respect for the laws of datasheets.

 

[McGizmo]

Have you contacted Nichia with an "Expectation of sudden death" projection request? /ubbthreads/images/graemlins/grin.gif

 

[swamp40]

Thanks for the lead, McGizmo!

Here's the link for posterity.

Wow - 225mA with a penny heatsink! I was feeling guilty about trying for 80mA.

No, I didn't contact Nichia.

I think we're going to add as much heatsink as we can get away with in a small space, and then increase the current until the cathode is stable at 50 degrees C with ambient cooling, and call that the maximum we can do.

I'm not very daring, I guess.

If that's not good enough, I'll try talking them into a different led.

I noticed you got your hands on some 2W nichia NCCW023E's. That would work for us, too. Wish they were for sale on nichia's website.

 

[Jonathan]

Hey, a Luxeon emitter is only 8mm in diameter or so; use that and you will be heat sink limited rather than die limited.

-Jon

 

[Rothrandir]

if you're open to useing a nichia2w, would you consider a luxeon 1 or 5w?

the one watts can get in upwards of 60lumens when overdriven, and the 5w's can get in upwards of 180when overdriven (both depend greatly on the individual led...these results are not typical)

 

[snakebite]

is the led replaceable or is the whole product a throwaway?
if so seems like a waste to have anything but batts, resistor(if any), and led.

[ QUOTE ]
Doug S said:
[ QUOTE ]
brockrobinson said:
If I wanted to run an S-ranked Nichia NSPW500BS for only 1 hour, how much current could I run thru it?

It would be a single use application, thrown away after 1 hour, and I'm willing to moderately heatsink it.

It would be driven with a zetex zxsc100.

Does anyone have any experience of the maximum overdrive capabilities of these LEDs?



[/ QUOTE ]

As has been implied already, the maximum current for a 1 hour life expectancy will depend upon heatsinking. Be aware that this maximum current will be likely to be greater than the current at which you would get maximum light output if this matters.

[/ QUOTE ]

 

[swamp40]

Yes, a luxeon 1W would work, too - if we bend the leads back. Just more expensive.

I wish they'd connect the heatsink to the cathode, instead of telling you not to use it electrically. I'm sure there's some good reason for it, though.

That'll be our backup if we can't get the light output we need.

I agree it's a waste, but I haven't found any battery-only solution that will put out what we need, and fit.

The led, circuitry, and battery all have to fit in an incredibly tight spot ( approx. 8mm diam x 45mm long).

It needs 80mA in the beginning, ok to go down to 60mA after an hour.

I tried 2 stacks of 4 LR41's (silver oxide)directly driving the led with no resistor, but they go to hell after 5 minutes of 40ma (per stack)abuse.

Similar w/ alkaline buttons and zinc air.

It has to sit for up to 2 years before being used, so rechargeables are out.

Can't find any good lithiums that small, so I figured the only thing left would have enough power would be an AAAA alkaline.

Now I just need to figure out where to put that big inductor the zetex chip needs. Thinking about winding a coil all the way up the AAAA.

 

[snakebite]

what about 2 cr 1/3n lithiums.or 2 2l76
3v ea and a resistor.
good shelf life 10 years.

 

[swamp40]

I wish! Those would be perfect.

11.6mm diam, though. Too big, I'm afraid.

Wish someone made some slightly smaller ones, but I sure haven't seen any.

Panasonic's pin lithium batteries (BR425,35)are small enough, but it takes 2 in series just to get 20ma into the nichia.

 

[McGizmo]

Brockrobinson,

I wouldn't necessarily be too concerned with isolating the heatsink slug from ground. We have many healthy lights running now with boost circuits where the ground and sink are common. I guess it may be a limitation due to your circuit?

- Don

 

[swamp40]

McGismo,

You've got a lot of experience, so I believe you - but why does it tell you not to do it in all their datasheets?

"Electrical insulation between the case and the board is required. Slug of device is not electrically neutral."

 

[B@rt]

How about Spider LEDs?

LEDmuseum has a page about them... /ubbthreads/images/graemlins/rolleyes.gif /ubbthreads/images/graemlins/icon3.gif