[WIP] 17mm DD+single-7135 driver / single sided / Dual-PWM

SIR800DP yields best overall results, especially when the cell is low.

PSMN0R9-30YLD is close, but falls short with a low cell. PSMN3R0 can’t compete, at least not where max output is a factor.

This would be a different driver design, but I was wondering if we could make C1 as large as possible and use one of the MCU pins as a battery sensor (interrupt on disconnect). The idea is to see if the MCU can continue running for a few seconds after the tail switch disconnects power. In the absolute lowest-power mode it might be able to last a few seconds with the biggest capacitor, assuming it can somehow prevent that power from draining out to the main emitter.

The benefit is potentially removing the need for the OTC. But I’m estimating a minimum power of like 5-10uA at a few volts, so it might need like 60uF worth of capacitor in order to last even two seconds. The largest I’m aware of in that size is 22uF, and I don’t even know if the MCU can go to sleep fast enough or turn off the FET fast enough to make the idea feasible.

Sharpie suggested it originally, I think, and it initially seemed impossible, but with everything completely min-maxxed it might be marginally feasible. If I did the math right.

Lucky, eh? I guess v032: OSH Park ~

  • Corrected R1/R2 silkscreen.

In this case practical experience is driving my decisions. A datasheet’s recommendation isn’t golden. In this case we’ve got a driver which will be clamped into a metal retaining area. We’ve also got a 7135 with a thick slab of metal on the bottom which is doing much more than a 1oz trace ever will. It’s simply not going to help. Whoever modified the v013 layout attempted to follow the datasheet for no good reason in this case - it’s as simple as that. They also didn’t even get close to what the datasheet recommends FWIW…

Additional info:

  • 7135s behave very well when overheated. Even with the driver air-wired inside a big light I would not expect issues.
  • Current firmwares, AFAIK, generally run the 7135 at a very low duty cycle. It doesn’t really matter for the reasons I stated above, but I thought it was worthwhile to point out nonetheless.

Again, practical experience is what’s guiding me here. Take a look at the Nanjg-105 for another example where this is not a problem.

There are several issues here. #1 is that this driver is not intended for your application. Certainly another layout can be done, but this one is simply not ideal. Square peg, round hole.

There is no sane place on top to solder a 1.5mm solid wire and not rip off traces. IMO a good match would be plated-through-holes sized for the 1.5mm solid wire.

I’m not certain what your overall goal for that project is, but this is a hotrod driver. The v030+ purposefully skips current-carrying BAT+ vias and depends on a spring bypass. Anything which defeats the spring bypass is outside the scope of the v030+ layout currently under consideration.

IMO DD/FET drivers may be poor design choices for the sort of light you are thinking of (potting etc generally indicates something which is not a hotrod). We wouldn’t use a hot-rod engine in a police interceptor car.

As far as not trusting the bypass wire… feel free not to trust it. It’s necessary if springs are used. Folks here are using it. The big 3mm via is specifically intended to make it easier for less-skilled folks to do a bypass which holds up better and longer… (while also allowing Dale to use 18awg }:slight_smile: )

Once we hammer the details out I’m sure that a layout for non-bypass applications will happen at some point. If nothing else we’d simply replace that center via with a pad and put many smaller vias on the board as I’ve done with other layouts.

I use and recommend this free product: gerbv - A Free/Open Source Gerber Viewer It works quite well and handles the drill files properly.

I suppose that there are also leakage specs that should be considered?

I suspect that 100nF will work. We’ll see. The bounce is a good point.

One thing to consider is that while the MCU pin may be rated for XX mA, the FET gate could easily get much much more current than this during the turn on. I suppose that it’s kind of a moot point since we’ve got C1 though…. hmm.

Two points here:

  1. We really only need full saturation while we are at 100% duty cycle. Anywhere else who cares? 100% duty cycle is where we get no boost at all. If we were having a problem getting the gate voltage high enough during 100% duty cycle I suppose we could drop it to 254/255 but then again… if this was a problem we’d have noticed hot MOSFETs by now. :wink:
  2. FWIW the SiR800DP kind of makes this a moot point too. That thing is ridiculous.

Good point, Mike C would be a good person to ask. I selected PSMN3R0-30YLD myself back when I released the A17DD-SO8, but better FETs have been found for our applications - See DB Custom’s post #381 on the topic. FWIW I believe that Rufusbduck picked out the PSMN0R930YLD and comfychair picked out the SiR800DP. My testing earlier in this thread was done with the PSMN3R0-30YLD because that’s what I had it’s not bad.

I’ll take a closer look at the WP article, thanks. I see that it touches on the important design considerations.

We can look into a design for that, but I think it would be worthwhile to just airwire it for now. That might give us a better idea of feasibility & etc. Once a more concrete range is known for the C1 value we can attempt a fresh layout with an SMD larger than 0805.

Did I? I don't remember, but I only have a bookmark for the SiR404DP. Did anybody ever try that one?

I think it was me that found the SIR800DP initially, based on what Wight told me to look for in the spreadsheets. Then Richard looked at it and tried it, found it to be spot on, and it became the de facto standard for some of us.

I used 16 ga for the first time tonight. :wink:

This is actually an MTN 17mm driver with the positive contact in the middle.

Hmm… so you did… I see that we had a PM conversation covering that topic called ":-) retaliatory try this! :-)" back in October 2014.

So… in that case who identified the SiR800DP? Eh, apparently me heh… at the time I found it I must have recalled that PM conversation and thought that SiR800DP was the one you showed me. (FWIW note that I later realized that the SiS414DN which I mention in that post uses a different package / eg is unsuitable.)

I’m certain that I have examined SiR404DP at some point, but I couldn’t tell you a thing about it right now. :-/

EDIT: And DB Custom (then DBCstm) must have done the leg work! I certainly wasn’t shelling out $2 for an FET at the time. :wink:

I bought my first 5 SIR800DP from Mouser on Dec 15, 2014 for $1.83 each. :wink:

With one left in my kit, I have used 114 of the SIR800DP since that first purchase. :wink:

Used a lot of PSMN0R9 and 3R0 as well, and a few Toshiba thrown in for good measure. :wink:

Where’s the smiley with the big, wide, and alarmed eyes when you need it? Good stuff DB Custom.

I vaguely remember the Toshiba ones… they had a unique package with more metal involved. And maybe they cost around $3/ea? I dunno.

I bet that you’ve assembled more drivers in one day than I have total. :wink:

The Toshiba had a second metal plate on the top, not to be used for current but to be connected to a thermal mass.

I just did 25 in 2 panels the other day. Love doing em on a panel, looks so cool! Richard, now, is really REALLY making some drivers!

Sometimes I just do one, I have a small piece of sheet copper that I clamp in short straight stats and hold that in my vice, apply the soldering iron underneath. Occasionally I’ll reflow an emitter that way as well, if just doing something simple and quick.

Edit: Might be worthy to note that when I was just starting to populate those 25 boards it was storming and our lights went out. I used the 10,000 lumen BTU Shocker with triple 9V MT-G2s doing a ceiling bounce to be able to see to populate em. Later, when we got electricity back, I re-flowed them simultaneously on the stove top. :wink: Yet another light with a AW driver in it. :bigsmile:

For the record, the tiny 10mm FET’s with MMU and crazy small MOSFET’s are a PITA! The MMU has to be re-flowed onto a programming chip board, then taken off and put on the driver. All 7 components, virtually the same as our normal drivers, fit on a 10mm board. Those can drive ya bonkers!

Hey Dale, since you're up for seemingly absolutely anything, try the SiR404DP. It's got only about 2/3rds the resistance of the 800DP!

I'm just not sure about the gate charge/capacitance specs and whether it'll play nice when driven by a dinky little MCU.

On the way, should be here Thurs or maybe Fri.

Edit: ie, SIR404DP

Yet another FET that isn’t available where I buy components. Any thoughts on the SIRA00DP? I can get that one, and it appears to have pretty low resistance too.

If it turns out they work, Dale will end up buying a few hundred and he'll send you some. LOL.

Guess I’ll just have to get a SIRA00DP and try for myself.

Sorry, that was a roundabout way of saying I don't know how the specs (the gate characteristics) will affect things since I don't know yet how the 404DP will behave.

But at a glance, it doesn't look promising.

SIR800DP: (works)

Gate Charge (Qg) @ Vgs 133nC @ 10V
Input Capacitance (Ciss) @ Vds 5125pF @ 10V

SIR404DP: (probably works? maybe?)

Gate Charge (Qg) @ Vgs 97nC @ 4.5V
Input Capacitance (Ciss) @ Vds 8130pF @ 10V

SIRA00DP: (???)

Gate Charge (Qg) @ Vgs 220nC @ 10V
Input Capacitance (Ciss) @ Vds 11700pF @ 15V

It doesn't help that those aren't directly comparable since they are not at the same voltages (and also especially that I really don't know what happens when the gate specs don't play nice with the MCU).

Cool. I’ve just made a version of my FET driver (Mod: My take on the convoy S series with side switch mod.) with the PowerPAK SO8 and ordered some samples from OSH Park. I’ve got an order ro place on Farnell so I’ll just add a couple of SIRA00DPs, stick ’em on and see what happens.

The SIRA00DP works but doesn’t put out as high a current.

Apples to apples it might do 4.2A while a SIR800DP does 5.3A.

I did try some, great if max amperage isn’t required and probably a good option for those situations where a light is going to be used with a protected cell.

Thanks DB!

I got some to compare with the SIR800, built X6 lights with everything else being the same, literally. The output on the SIRA00DP was disappointing. The PSMN0R9 was very similar on a fresh charged cell , very close to the SIR800DP, but when the cell runs lower then the SIR800DP pulls ahead. Richard has found this to be true as well and highly favors the 800.

Found the notes…
Built 3 X6’s with XM-L2 U2 3D emitters out of the same tape. Samsung 20R cells at 4.22V
It wasn’t so much the amperage as it was the output…

SIRA00DP 4.59A at 1169.55

SIR800DP 4.59A at 1373.1

PSMN0R9 4.63A at 1373.1

Differences exaggerated as the cell dropped power.