17mm/22mm MTN-MAXlp - Low-Profile 1A-4A Programmable Buck Driver + 22mm MTN-MAX

Please excuse my ignorance. Richard, you said the 17mm 4-layer board did much better thermally. Are you going to make a 4-layer board for the 22mm design, or is it good enough at 2 layers? Are you going to be selling them at your store, and a parts kit as well? I’ve never built a driver before, so I don’t have any components lying around. Of course, I’d love to be able to buy the driver built and flashed with guppydrv, actually. I don’t know anything about OSHPark either. I just now registered with them and took a look around because I really want this 22mm buck driver!

Since these use attiny13 as an MCU I’m assuming that means that modes are made from PWM. I don’t know if that line of reasoning is valid (probably not, haha). Now that you’re selling these I want to know.

Also, what is the lowest low that the prebuilt 17mm design could do? If it indeed uses PWM, some info on limitations (frequency, duty cycle, etc.) for those of us interested in have custom modes programmed would be great. Thanks in advance, I know you’re a wicked busy guy!

One last thing, I know the voltage range for the prebuilt ones you’re selling spans 5-15V. What happens at say, 4.9V, if you programmed no LV warning? I ask because possibility of CR123a use is appealing.

Yes, the modes are PWM based on the buck IC, which can be up to 20 KHz on the input (We are running ~19KHz).

The moonlight level can be very low (The MAX16820 has a great dimming ratio).

At around 4.5V the buck IC will simply shut off. CR123s would only be useful in lower output scenarios since they are pretty current limited.

Would someone be willing to build me some of these in 22mm and flash the MCU with 3 or 4 mode levels plus hidden strobe? I need specifically a 22mm buck driver pushing right at 3A from 2S li-ion cells into parallel emitters, with a few modes plus (hidden) strobe. Richard has the 22mm driver listed at his site, but listed as out-of-stock. Plus, the only UI option he has listed that includes strobe is guppydrv, and it has no LVP. I really need the LVP, but I want strobe available, too. In fact, TK’s biking strobe/beacon that keeps the power to the emitter turned on at a low/mid level, with spikes into turbo, would be cool to have. I will have plenty of height in the pill for the external inductor. So… anyone wanna give it a shot?

David - I just got in 3 of the 22 mm PCB's in from OSHPark. I could order the parts kit from RMM, but I'm not clear on the LVP option - there is no order option, but in the description, it lists an option for no LVP, 2 cell, or 3 cell. So, I'm confused... Not sure if he means the option is implemented in the firmware, or required something different in the parts list... Just not sure, dunno...

How many do you need? In theory, I can get/or have the boards, order the parts kits from Richard and program them myself with firmware of my choosing for you. Just not sure bout that listed LVP option in the description.

I think LVP is in firmware. Richard has the driver listed with 4 firmware options. Only the guppydrv option doesn’t have LVP. The other firmwares have the option of ~6V for 2S and ~9V for 3S support. Right now, I’d like to get a couple to try out. (I learned long ago to always get one extra to break/lose/burn/whatever.)

Hey guys, I hope nobody is really invested in the 20mm boards. They work great at lower currents, but if you try and get 4A+ out of it they bug out. I screwed up on the layout and need to redesign some things. So far the 17mm and 22mm are solid and I have been using them pushed hard in a few of my personal lights, as have several others, but the 20mm needs to be tweaked.

In short: if you have plans to built a high-power 20mm driver, hold off.

On a positive note, if you want a solid 5A 17mm driver, the 4-layer PCB has been running great for me. I've been running it for a few weeks now and have built a few and they are all working great.

Great news about the 4-layer board. Is there a reason you haven’t shared the Osh link for that one?

Have just been testing the crap out of it and have built a few of them. I usually make a few tweaks after the first run. I'll get around to it soon.

MT-G2 Efficiency? I had a customer ask me about the potential efficiency gains at low amps (2A) with an MT-G2. I did a quick test as quoted below:

5A 17mm board ? Yes please ! how do i order one of these ? I was going to make an adapter for the 22mm board for my 1405 but this will save me the trouble.
Thanks

I still can’t get a working example. I’m tried 3 times and no success.

17mm? I have built about 50 of them so far and they've all worked. 20mm--well, you read my post earlier (no go for most setups). 22mm I've built and have been using about 6 of them in lights and they've all worked so far.

A lot of the issues you'll run into is that reflowing these boards properly is much more difficult than anything else we usually do because of the tiny pin pitch and non-existant leads. A stencil may help a little bit (although I don't use one for these), but really it comes down to some practice and then following up with a manual reflow of the leads with your iron on the sides of the flat packages after the initial reflow, if needed.

Soon! I have been testing them and I have a few test samples going out to other members and flashlight guys as well to make sure they're 100% before the "official" release.

Richard, can you please post pictures of a 17mm completed driver?

I'll take some later this week when I build another one.

I finally got my last set if parts to work! About time.

Great! Did you figure out what made the others not work?

The first two I have no clue. The second one I made wouldn’t work so I put it away to take a break. I got back to playing with it a couple of days ago and absent minded me fried it. I forgot to change my test bench setup back to 2S. I inserted the batteries like it was 2S in my side by side battery holder. Well, it was 1S and the way I have it set up also means it was reversed polarity to the driver. It smoked. I dunno what fried but something did. It also blew the LED too. I’m just gonna take all the components off my first one and reflow them to see if I can get it to work.

So for future reference to others, 1S reversed polarity doesn’t get along with this driver :wink:

Good to know! :stuck_out_tongue:

I haven't tried to reverse one, but I think that cerealkiller said that he had reversed polarity to this same IC before and nothing happened. He said he had even measured the LDO output and it also didn't reverse.

As far as the non-working drivers go: I can almost guarantee you that it's your reflow of the MCU, Buck IC, or both. The MCU is usually the culprit.