Compatible driver help needed!

Hey Guys,

New here so go easy :smiley: Ive been avoiding joining to help curb my addiction but ive finally gave in as i need your expert help :smiley:

Im looking for a driver suitable for this led - LZ4-40R108-0000.

Preferably single cell, ideally no bigger than 22ish mm, but im open to all suggestions. My main concern is that there are single cell drivers capable of 12v at 22mm, however the maximum permissable forward voltage for this unit is 11.6v @ 700ma.

Thanks

Any takers?? :frowning:

Yup

http://kaidomain.com/S026504-H2-C-22mm-1_5A-1-or-2-cell-1-Mode-or-5-Mode-Boost-Driver-Circuit-Board-for-Cree-XHP35-XHP50-12V

is the one I can think of right now

Rated current per datasheet is 1000mA constant /1.5A pulsed, you probably can feed that thing 1.5A w/o problems

I know it’s none of my business, but… are you sure you want to use this LED? You wouldn’t even have to use a boost driver and use a buck instead with all 4 dies in parallel, but this is insane…. Good luck with the MCPCB….

Unless you got this figured out already…

Thanks for the help, ive already ordered that driver a few days ago so feeling slightly better about myself now :smiley:

The LED comes on an mcpcb, i have 2 sat in my bits box.i want to use this led as its really bright, and will be going into an aspheric, however the company i bought them from cant supply binning info, so may have to order 1 from somewhere else once i get the thing working.

Can you explain more on the buck driver idea, im not following (lack of sleep)

OK that’s good to hear.

Well that depends on the MCPCB. The ones I see are all in series though the LedEngin site references one that has separate connections for all 4 dies, so you could run them in parallel from a buck driver which would probably give you somewhat better efficiency (and more driver choices!)
(Part no. LZ4-2xxxxxx or LZ4-2xxx00; another one that looks compatible is LZ4-Vxxxxx, copper / probably DTP & much better thermal conductivity , this one uses that).
But looks like these aren’t sold separately, only with emitters. Try what you’ve already got & see how that goes.
If you want to drive this as hard as possible, the Cu MCPCB may be worth the upgrade (regardless of the driver used).

Regarding binning, if you buy in small quantities it’s rather unlikely you can shop specific bins. A small distributor might be able to have a look and tell you what’s on the reel but that’s about it.

Just checked, its on a 5 terminal aluminium mcpcb, so could be driven individually.

I wasnt too fussed about massively overdriving this, as its super bright already, although the binning variation from dimmest to brightest is double, so if i have a poor bin i may have to.

No, I don’t think so. This has to be in series.

Yeah you’re right, i never got that far down the spec sheet, ill have to stick with what ive got for now then possibly change it up after testing.

Do you think that the 12v supply will be ok? Its 0.4v above absolute maximum, and 1.2v above the recommended 1000ma forward voltage rating.

You have to think it the other way around. The driver is capable of boosting up to 12V at current X, and since it’s current limited, it will feed the LED whatever voltage it draws at that current.
This particular one seems to step down from 1500 to 1000 mA after 60secs on High. I think that should be fine (see below) , but if it’s too much you can always mod the sense resistor to lower the current. And if the driver does not boost higher than 12.0V (those numbers are usually just ballpark figures though) it won’t supply more than ~1300mA estimated, with this particular LED.

The datasheet also gives the thermal characteristics: 2.8°C/W for the emitter + 1.1°C/W for the MCPCB =3.9 total. Max junction temperature is 125°C.
Looks like there’s plenty of headroom at 1000mA, but ultimately it depends on the host (and usage of course).
(The total thermal resistance with the copper MCPCB is 25% lower btw.)

I understand about the voltage draw now, its been a long day, you’d never guess i was an engineer :person_facepalming:

I had a look earlier for a copper mcpcb, but i think the only viable option would be to buy LZ4-V0MD0 as you suggested earlier, and swap the led’s over. This would then also allow a buck to be used.