GXB17 Driver – 17mm 6V 3A / 12V 1.5A Constant Current Programmable Single-Cell Boost Driver

GREAT!


Impressive!! :wink:

This is what I call breakthrough tech! Great work.

Are there any functional shortcomings to the 17mm driver which the 20mm driver doesn’t have? It looks like you have to use smaller spring to save space - don’t know how that affects function.

This is what we have been needing for a long time. If it can handle 20W long term that is perfect for most edc style lights and a turbo burst of say 30W would be perfect.

I assume that it could be tweaked to boost up to 12V for an XHP35 correct?

Very nice !

=
“For programmability, I decided to go for an Atmel ATtiny84A instead of an Attiny85 due to the fact that it came in a very small 3x3mm QFN package, has EEPROM for storage of memory modes, allows me to use the hobbyist-friendly Arduino environment for sharing / open-source, and comes with a lot more GPIO for additional features.”

open source firmware ?

I hope not! It shares basically the same schematic except for a few components which are smaller / more power dense, but otherwise will have all the same features. I don't see how using a slightly smaller spring would affect the function, but to test this out, I've also ordered a Convoy S2+ host to build this driver into a real flashlight to see how it does in real life.


That's correct. I plan to make 2 versions on the bench to test - a 6V 3A nominal one hooked up to a 144M/XHP50, and a 12V 1.5A nominal one hooked up to a XHP35, and see how much I can push them. The difference between 12V and 6V versions would be modifying a few of the component values for better efficiency at the desired output voltages.

Yes I will be uploading all the schematics and firmware to my webpage soon so anyone can modify it to suit their needs or contribute to make it better! I'm not the best designer or firmware writer and I'm sure there are lots of folks here who are far better than myself! :)

Oh yeah! 12v and 2.5-3A 17mm or 20mm driver would be crazy :heart_eyes:

I doubt that very much!

2S 8.4 volt in to 12v-2.5a would be feasible.

I kind of doubt it will be able to handle 3A at 12V but 2A might be possible depending on the exact efficiency involved. Although 2A is about perfect for an xhp35 for longer term use, over that and you get quickly diminishing returns. Although a turbo mode of 2.5A for ~45 seconds or so could be possible.

I am using a H2-C running at 2A with 1s input now so i know it should be doable.

I will be happy with 2A aswell if i can program the driver :smiley:
And a little turbo mode cant hurt aswell hehe

Triple XHP35 doesn’t have problems with diminshing returns after 2A. :wink:

This is awesome. Please tell me you are going to offer these for sale? I want a Convoy C8 with an XHP35 so badly.

Nice. You are very clever loneoceans. :+1:

Nice joke ) or are you diver?

If one of these could be made in 36mm and be programmed to do 1s —> 12v@1-1.5A for E-switches then this would be awesome as a TN4A driver with the carrier modified to run 1s4p.

Have you thought about making a 9V version too?
It would be useful for 3s 3V setups, bringing better efficiency than linear drivers.

Would love to play with one of these when they are working. What boost IC are you using? From the pictures in the GXB20 post it looks like possibly TPS61088?

TPS61088? The official datasheet lists 12.6V as maximum output voltage, with 13.2V output overvoltage protection. That is pretty limited for XHP35 handling, though it may suffice for just 1.5A of output.

I could be wrong about the IC, but the pictures of the assembled GXB20 look to have a similar footprint. I skimmed through the GXB20 thread and didn’t see the IC model mentioned, maybe I missed it. Will wait for loneoceans to chime in. Either way this is a very exciting driver.

Yes the GXB20 and GXB17 both use the TPS61088 boost converter. Barkuti is correct with the maximum output voltage possible is not much higher than just over 12V, which does limit output of the XHP35 to just about 1.5A in most applications. However keep in mind that the (1) I designed the GXB20 specifically for 6V 3A operation and (2) driving the XHP35 to ~1.2A will already produce 300% rated luminant flux (though with proper heatsinking etc more is just fine) and (3) the GXB17 was done over a weekend just to port the GXB20 to a smaller package!

So yes it's definitely not a 'ultimate' driver right now, but hopefully with a bit more time, I can get closer to it. :)

[quote=Agro]

As for 9V output on one cell, sure it's not a problem. Just need to look into refining the component choice (if at all) and it should work just fine and at full 18W+ power output.

Finally, I note that TI just very recently released the TPS61178x which was only available for purchase just after I had designed the GXB20. This is an even more attractive IC with essentially the same power handling capability and with 20V output max in a slightly smaller package, but compromises with higher resistance internal FETs, is difficult to hand-solder, and... is $5 instead of $3 which is a significant BOM increase. I will be tracking PMICs closely and see if the future mk ii versions of the GXB20 and 17 can benefit from them.

Once I get the GXB17 up and running I hope to get some feedback from members here and see how I can make better :D