LED drivers and Accessories you want, but don’t exist

But here it does. Think about it.

Can somebody tell how many vias from one board side to the other I need for a given current? Which diameter?

Just wondering if you order the 25V then on your board is the diode after the LDO missing for OTSM

It doesn’t need a diode if you get the right LDO. I have the TPS706, which has a lower reverse current than some diodes (10nA out of IN pin, 100nA flowing into OUT pin). Here’s the datasheet: Datasheet TPS706

And for the current per via, there are some websites, just google it. I used roughly 1A per 10mil via on the plus side.

Yeah, you have to check diode current when hot, not the quick-spec sheet, as it can be wildly different (exponential with temperature). The plots look like about 2uA. That should be good.

I just posted 1.7.1 of Bistro HD. https://budgetlightforum.com/t/-/44344

The OTSM-LDO-fetonly hex should work for your driver, although with no real moon mode solution yet (I'd prefer the hardware two-PWM channel solution to some PWM hack, but we'll see). I guess I should compile an OTSM-debug hex for you too, but we can see how it goes.

Thanks!

Found some information meanwhile:
http://circuitcalculator.com/wordpress/2006/01/31/pcb-trace-width-calculator/
http://circuitcalculator.com/wordpress/2006/03/12/pcb-via-calculator/
http://www.blackstick.co.uk/pcb-design-calculators/

Is there any interest in a board bigger than 17mm?

Yes, 20mm and 22mm are sizes I use a lot. 17mm doesn’t interest me much anymore as aside from my P60 drop ins almost everything has now been bored out to accept 20mm.

I could use a bigger one with attiny85-sized SOIC8 or flashing pads/vias for development purposes… doesn’t have to be used in an actual light, but convenient reflashing would help a lot with adding support for the hardware.

Oh, um, probably also large pads for an e-switch. Small pads break off easily when the driver is air-wired and gets moved around a lot. Again, for development purposes only.

Thinking About It.

(pic taken two weeks ago at my friend’s house)

So you mean some kind of development board? So doesn’t even need to be round? I would make one with bigger pads, vias (or pads as well) for flashing, some “wire loops” (don’t know the name) to get an oscilloscope connected. Maybe there’s a way for two ATTinys, 85 and 25v, and just with a switch (or a few) you could switch between the most used MCUs for different firmware. Or some kind of breakout board (like on Arduino) with one of the MCUs on it, and you could swap them.

With older driver designs, a dev board wasn’t relevant because it had plainly exposed pins with room for a clip. It’s only on newer denser boards that it matters. But yeah, a dev version would probably help with getting code support.

Once the hardware is understood well, development for this boost driver can be done on a one channel fet driver. It's just for testing the low modes and making sure that voltage control works out where the real thing could help initially as I see it.

This is like a “name your wishes” thread, I like it :smiley:

So, my first wish:

- buck driver,

- up to 20-21 mm (or 17mm even better, maybe two board design)

- 8.4V input

- output for XML/XPL 3V leds

- up to 6A

- based on Tiny13A so I could load custom firmware

- 2 switches, forward clicky for on/off and electronic switch for changing modes

  • from: oshpark or china (sorry, ordering from states is just too expensive)

that would be about it :slight_smile:

5A Buck-boost driver for UT-02 to push this light over 500 kcd.
Reference:
http://www.candlepowerforums.com/vb/showthread.php?440679-NEW-WORLD-ORDER-4-THROW-V54-World-that-is-HaHa\*&p=5161053#post5161053

ADDED:
I haven’t measured if it fits, but buck from 2x26350 may do too. :wink:

I’m contemplating tweaking my Q8 with XHP35 HI.
I’d like something that can sustain as many candelas and as many lumens as possible, so I need efficiency.

I don’t have the skills for such mod yet, but it doesn’t stop me from seeking options. :wink:
2s~~12V boost with XHP35 seems like a natural choice. Or even 4s>24V. Buck 4s12V could work as well, just like boost 1s~~>12V.
Is there anything that would work well in such setting?
I guess BLF GT, but it won’t give good current to 4 LEDs, will it?
Something else?

The BLF GT driver in stock form would be able to drive them at around 1.25A each, maybe a bit higher. If you upgraded some components it could do around 2A each.

Not great, but not bad either. Turbo won’t be as high as possible, but 8A is significantly above what Q8 can sustain anyway. Will fall out of regulation before batteries are half emptied. And efficiency should be good, right?

2A to each xhp35 is where the trade off in lumens vs efficiency starts falling real bad.

You will have a big issue with falling out of regulation though with 4 LED’s and only 4 cells.

1.25A on stock GT driver with 500kHz frequency possible

I am working on an upgraded GT driver
I am discussing with del the needed changes
So far Buck frequency changed from 800 to 500kHz
input and output caps doubled, the design already has pads to fit 2 caps instead one
Diode 3A to 5A
inductor from 6A to 15.5A

6-8A should be no problem to get to
10A might be possible but that’s about the current the XHP35 get not much gain over 2A anyways