Driver recommendation for 5w UV LED

Im wanting to build a UV flashlight and have settled on an LG3535 LED.
To drive this at its max, I dont think a linear driver will quite handle that, or not for long anyway as the battery voltage slowly drops.
With a 7135 Driver, I cant do any more than 1400ma, and the brightness will slowly drop over time.
Are there any other options, since this is a single cell light and the LED is rated at 3.6V, which is about the same as a lithium cell to begin with?
All the boost drivers are typically designed for 6V or higher LED’s.

What im really needing is a constant current boost/buck driver rated at 5W output for a single cell. Does such a driver exist?

ZAR 429.56 | convoy C8 with LG UV365nm LED ,includes extension tube
https://a.aliexpress.com/5pqfxDG3Z

Ask Simon if he can sell you the driver separately.

That light looks like it might have a buck driver, since that light takes 2 cells, although it does look like it has the ability to screw into two and take a single cell.
No harm in contacting him I guess.

http://kaidomain.com/Flashlight-DIY-and-Tools/Circuit-Board-Driver-Board/BD39-17mm-1_5A-3V-9V-1-cell-or-2-cells-1-Mode-Buck-Driver-Circuit-Board

Or that. But I can’t think of any buck boost driver for your specific needs. I’m also going to do a similar build and also want constant 1500mA current until fully depleted batteries. Looks like 2S is your only hope. Maybe 2x protected 18350?

Ive been looking on aliexpress and see this 1.15€ 10% OFF|CREE XP G 5W xpg2 XT E xte LG3535 XPG3 led treiber 17mm 3 4,2 V 1.2A 5 Modus LED taschenlampe Fahrer für CREE XPG2 Diode Emitter|Lichttransformatoren| - AliExpress
Looks like I can run at least 1.3A.
There are a bunch of similar drivers, its hard to work out what the specs are on some with their sketchy details.
Look at this for example.
How is 2A possible when the battery would only be able to manage that for a few mins at most?
2.19€ 15% OFF|16mm Durchmesser DC3.7V 5 Modi Led treiber Eingang DC3.7 4.2V Ausgang DC3.7V 2A für Cree XM L XML T6 High Power LED Emitter Taschenlampe|led driver|led driver outputled driver led - AliExpress

They look 100% like linear drivers with the lack of coils and the narrow input voltage.

I don’t know what you mean with a few mins, with 2x18350 I think a buck driver should last about 40 minutes at 2A and a bit over 1h at 1.5A, but I don’t think protected 18350 will fit in 18650 tubes, 2xunprotected are 70.x mm long, they may fit or not. The C8 UV builds you can buy in USA at inflated prices typically come bundled with 2x16340 as that size will fit, maybe a 21700 host will work better for 2x18350 but the driver may need to be adapted.

Thats the sort of driver I was thinking I would need, but they are not a constant current driver.
Most of the drivers I see with the coil on them are buck drivers, and any boost drivers are typically designed to run a 6V LED, hence why any single cell drivers are simply linear drivers.
Seems its the only real option from what I can make out.
Perhaps another option could be to go with 3 or more LEDs and use a boost driver?
A lithium battery is usually around 4.2V from fully charged, but drops quite fast down to 3.6/3.7V, so around this time I imagine that the brightness drops off and slowly goes down, rather than staying at a constant level.
Im not sure how it works when you are using an LED close to the battery voltage, since you kind of need a boost and buck converter at the same time depending on the level of the battery.
I was exploring the option of using 2x 18350, and I think they would fit inside a convoy host.

Edit:
Just found this here, http://kaidomain.com/Circuit-Board-Driver-Board/KX05-17mm-1-cell-1-Mode-Flashlight-Driver-Circuit-Board-for-IR-LED?limit=100
May be the closest thing I can find? 1400mA is better than nothing i guess. Also says suitable for UV LED’s so is probably designed for this type of LED

@ nzoomed:

Your link doesn’t work - missing “led”

here

Sorry, thanks for that.
For some reason it breaks the link sometimes.

I remember loneoceans was going to make some buck boost driver here: High Efficiency BLF Switching Driver? - Request for Desired Features Maybe you can ask him for idea for this project? But I do not see any news in recent.

The Convoy buck driver from the C8 UV mentioned before can be found here. A few weeks ago I built a UV light using this driver with S2+ host and 5W LG UV LED. It’s not buck/boost but it has a consistent output if used with two cells. Works well with 2x16340 or 2xCR123.

The sense resistor can probably be changed to adjust current if you need a little more.
This looks to be a PAM2803 boost circuit with the output controlled by a Fet.
If it is, its direct drive with all the components in the leds current path limiting current including the sense resistor. Once the battery voltage drops below the vf of the led the PAM2803 boost takes over. I’m just guess judging by the number of componets I see on the board.
Similar to this driver.
But the one you linked uses better components and a fet to handle the higher voltage and current.
Just a guess :smiley: . PAM2803 drivers are pretty reliable in my experience.

Probably not a bad idea to contact him and see what he thinks.
its not a bad idea for such a driver, as there are lots of 3V LEDS out there using linear regulators on single cells that are not very efficient.

Thanks, I might try this one and see how I go with 2 cells instead.

Thats good to know, I think the best option is to try a few of these drivers and actually measure the output current and compare performance etc.