Me to buddy, seriously doubt that tho, plus it will be a taller than a typical BLF driver by a good amount too. Especially with that big 2512 sense resistor (the size that comes on SRK’s) I just don’t see it happening in 17mm. Maybe with 2 1206’s stacked like my RGBW drivers but IDK about that even.
Thanks for this. In my reading, I’ve seen a lot of people saying that switch mode power supplies (SMPS), like a buck driver, need a fair amount of empirical testing. Does using a commercial buck controller help much with that, or is it still important to do careful testing?
I hope this gets enough play to get stickied.
Once you have a proven and functional circuit I'll be happy to have a crack at designing a 17mm version.
Thanks for a great plain English explanation, will be following this with great interest.
Cheers David, _who has just seen his big head Courui cowering in the corner_ J)
This is awesome. Thanks for the writeup!
Love your contributions towards the community.
It’s always important to do testing, even on non-SMPS designs, but yes, using a chip like this makes it much easier to get to something that works very quickly. There’s always a lot of opportunities for optimizing the design after the initial attempt if you have the means to do detailed tests.
For example, in this design, I chose a big inductor because of Maxim’s test circuit, but after a crude saturation analysis, it appears that we could use a much smaller one. If space isn’t an issue, you could just stick with 33uH and have very low ripple, but if we’re short on space, I’d order a few smaller inductors and then measure the frequency that the converter decides to run at - if it doesn’t approach the 2MHz limit, it will work just fine.
This is way beyond my realm of expertise and totally fascinating. Subscribed.
tterev - any chance you’re in the Triangle area? I’d like to buy you a beer sometime (and/or check out some of the lights you’ve made).
On the design of the board, you Can use 0603 pads for space, and still be able to use 0805 components, it is a “high density ” pad footprint, but you already knew that 
Awesome thread, let’s get this sukka started 
Both mattaus and wight had good designs but haven’t heard much about them late
To save board safe would the Atmel ATtiny10 be sufficient, I found a PCB based ZIF socket, might work for programming, just need a good code writer to whip up an awesome UI ; )
For a power cycle only, more simple UI yes it’s probably enough, plus with the attiny10 a 10f322 is a direct swap, same pinout between AVR & PIC. One thing tho is no voltage divider input so no voltage monitoring on the attiny10
With the initial design being for a dual switch light (courui is side switch only but I’ll be installing a tail clicky) it’ll have to be something bigger to run momentary FW.
Ok looking at the Vishay SL42 datasheet (covers the SL43 also) I see that the IF (AV) rating is different from Al to FR4 and that on FR4 its only 4A, is this still safe to use at 8A output on an oshpark board (albeit with a large Cu pour) considering that?
I didn’t notice that, good catch. Probably best to find a different one
Allright here's my parts list, look good?
1 MAX12820
2, 3, 9 1uf 16v 0805 (I have a reel of these)
4 Vishay Dale 2515 .025ohm 2W 1%
6 Diodes inc Schottky 10A 40V PowerDI™ 5 (I choose this slightly more expensive and higher rated diode for a few reasons, one being this package is smaller than the more common DPAK and also because while its more expensive individually it offers a better bulk discount)
7 AOD510 (exceeds all requirements, has great low RDS(on) and I have a hundred of them)
8 For my use a 12F617 but probably make an ATTiny13A version at the same time for everyone else
10 470ohm 0603's cause again thats what I already have on hand
hopefully links work, digikey is strange...
Tiny10’s can have issues being programmed in C. Like very easy to run out of RAM and stack space.
Yeah, just outside Raleigh; I’d love to
Looks good to me. The links didn’t work, so just be sure the Maxim part is correct since it looks like there’s a typo in the part number
Awesome man… So after this is out we should have a go to buck and direct drive in the blfdd?
Allright guys, after a little bit of a headache here’s the .sch. Now I need to find the dimensions of a Courui driver, anyone got one to measure?
Double check the direction that diode is facing
5-8 amps with constant current? If this driver turns out well, then ill just say...
Good catch, fixed. And while I’m waiting for either one of my Courui’s to get here or for someone to hook me up with measurements, just for S&G’s I thought I’d see if it’d fit in 26mm, definitely not even close!
