17mm & 20/26/27mm single-sided DD/FET driver release: A17DD-SO8 / A20DD-SO8 / etc

You may use the same parts you’ve been using with two exceptions:

  1. Most important: a DPAK sized FET will not fit. You must use LFPAK56/Power-S08, such as PSMN3R0-30YLD - Mouser / Digikey / Farnell (for the rest of the world).
  2. If you choose to use 19.2k for R1 instead of 22k you will need to adjust your LVP in the firmware before flashing. If you are using a pre-flashed ATtiny13A with LVP you must use 22k for R1. 19.1k will result in LVP allowing VERY low voltages. I highly recommend that you use 22k and be done with it. Digikey / Mouser / Farnell (for the rest of the world)

Some of our more determined friends here may prove that a DPAK FET can be made to fit upside down with some major filing. Basically the same filing you’d use to install it on a Nanjg-105c. IMO it won’t be worth the effort when you can install the DPAK FET on a Nanjg-105c or you can just drop in an LFPAK56 FET on my PCB no muss, no fuss.

If anyone wants to contribute any good eBay / Aliexpress links I’m all ears. :wink: Not everybody can buy through these distributors.

Here’s a link for 10 pcs.

Edit- couldn’t find data on this particular FET.

That is just awesome.

Really looking forward to ordering and trying to assemble some of these.

The problem with eBay links is it’s quite often hard to find the relevant data sheet for that particular FET and Rds on values can vary from absurdly low 1-2 mohms to more than 10mohms. Mouser at least gives data sheet links for each FET listed so you know what you are getting and will show the values for 4.5Vgs and 10Vgs as well as showing a graph from which you can interpolate behavior between 3-4V. Once again, the eBay crap shoot.

I think this is it: http://datasheet.elcodis.com/pdf/6/6/60632/ph4030al115.pdf

As you mentioned Vgs is important. In this case the Vgs graph just stops at 3.75v (where it’s still only <5milliohms but appears to be close to going vertical). Frankly that looks pretty similar to the FET I’m using as well as pretty similar to the DPAK AOD510.

Actually….

What about PSMN1R2-25YL? It’s late at night and I can’t go find the answer to how much gate charge the ATtiny13A can handle, but I think that that FET has a low enough gate charge (Qg) at <5v. The Rds(ON) figures look great to me, much better than the other FETs we’ve mentioned so far. I suspect that PSMN1R2-25YL would not be a good choice for Zener builds but might be very good for regular builds. I see them on eBay and I see that Mouser has them on order. Farnell has PSMN1R2-25YLC in stock, that’s not the same thing so watch out for that!

So, uh, here’s a thing I’ve never seen before…. http://cdn.vicorpower.com/documents/datasheets/Picor/ds_PI5101.pdf
It’s not actually smaller than LFPAK56, but the specs are crazy. Also they cost $5/ea, heh. And this is the only part I see on Digikey with that form factor.

Saw this design the other day when poking around oshpark wight… Didn’t know it was yours- I was thinking that’s kind of neat one sided board

Sweet, wight. Thanks.

Wight, I noticed your solder joints are pristine on this. Did you use a mask for solder paste or apply with a syringe?

So Wight, will that Picor FET replace what we’ve been using, with much lower Rds on? Looks like it’d be a very neat and trim package to produce a slimline driver with great characteristics.

And yes, really like the looks of your new driver! I have 4 of those FET’s, will probably be trying a couple of those…just ordered a bunch of re-stock in the traditional caps and resistors wouldn’t you know it!

20mm version:
w/ 1mm exposed copper on GND rings.

https://oshpark.com/shared_projects/YeNzvLPx

Added to OP. I made no changes other than expanding the diameter and increasing the exposed copper from 0.5mm to 1.0mm.

Glad you like it fellfromtree. You should see the mess it’s based on. :wink: Check out the OP here, it shows v008 of the design which spawned this: [WIP][mostly retired] 17mm DD+7135 -- linear regulated driver w/ FET turbo

You’re welcome. I’m using a syringe of Kester EP256 (Easy Profile 256) from CML Supply. If you click through to the big version of the first pic in the OP (the picture with the tweezers) you’ll see that my application isn’t really perfect - R2 has a lot more solder than R1. Due to the low quality of the picture what you probably can’t see is that I reworked D1 with my soldering iron after the reflow. I was out of normal sized diodes so I used the tiny SOD-723 size. It blew around during the reflow process and was hooked up correctly but kind of askew and unattractive. That’s why those pads appear slightly shinier. To better illustrate, here are 3 pictures showing the components laid out without paste, then the components partially placed after adding paste with the syringe, and finally the initial results of the reflow (before rework). Sorry about the focus in the second pic, it’s on the back of the PCB rather than the front.


Is anything different needed for a Zener application other than adding the Zener to the board?

BTW, I forgot to ask: what are you using?

The Picor is fairly long/big and fairly expensive. It’s also a no-leads package, making it potentially difficult for novices to work with. I think that it won’t replace anything for now, but we should keep it in mind in case the need for such an extreme FET should come up. There is also the supply issue: AFAIK there is literally only this single FET which uses that package. If Picor stops making production runs of these things then any designs based on it are squashed. Frankly I haven’t even looked at it that closely, I suspect that the specifications probably preclude this use anyway. Yeah, take a look at the maximum Drain-to-Source voltage: it’s 5v. It wouldn’t be able to handle the spikes from single-cell DD use I think, and it certainly can’t handle 2s use.

Zener application works just like you’d expect. Use the same part (SOD-123 size) and be sure to replaced D1 with an appropriate resistor.

I think you use a different value for R1 on the Zener version.

Heh, good point RBD. For voltage monitoring on the Zener version (which I have not built) I’d think you’d want R1 to be in the 47k - 50k range. EDIT: (for 2s applications)

This is totally awesome btw... I haven't totally absorbed this all yet, but seems quite easy. Some Q's:

  • WTH is a "OG" XM-L and HTH (how the hell) can it take 9A?
  • Is this PSMN3R0-30YLD FET as good or better than the classic Vishay 70N02? I'm unclear bout this - seems lower resistance? More amp capability?

  • How did you make this driver sexier than hell? Smile
  • Why are you making it so tempting to order your boards and a bunch of parts? Smile
  • Why are you making me feel like a fool for not keeping up with all these going's on's? Smile

Those LED wire pads are huge!! Is that some sort of new record? Can we use 14 AWG LED wires? Smile

Thanks Tom E! Remember, this driver has only seen limited testing so far, so I don’t have all the answers.

  • Original Gangsta. It’s just a plain Jane XM-L. This one was previously in a SF dropin. I used two different HF meters to measure the tailcap current, several times. Current falls immediately, I’d estimate that less than 1s is spent over 9A. This is due to both the battery sagging and the “immediate turbo rampdown” firmware. This weekend I’ll get the dropin wrapped with foil and shoved medium-tightly into a host. I’ll run it for the full 30s+ and see whether it survives and how hot the host gets.
  • It’s unclear to me as well. The Vishay 70N02 datasheet is missing some critical graphs that I’d use for an easy comparison. It appears that the PSMN3R0-30YLD may be better for 1s applications. For Zener builds I think it’s pretty clear that performance should be identical for the two FETs.
  • Pseudo-triangles Trade secret.
  • Dark evil plan to bankrupt modders. Kindness.
  • ! Now you know, and knowing is half the battle?
  • I don’t have 14AWG; I guess I’ll have to try 12AWG and see? Really you should be able to install whatever you need, but I think that soldering to the triangular-ish center pad may be the most fiddly thing about assembling these.

I just yesterday ordered a dozen of these boards and the accompanying stencils to make life easier on me.

And I just a few moments ago opened a package with a proto board to assemble. :slight_smile: So today it’s off to the races! Yippee! Even got a light to mod so it’s a good day. :slight_smile:

Hell can be pretty sexy, so I don’t know about all that, but this is definitely a nice looking board! The one-sided design is VERY appealing!

Just from reading sales blurbs the LFPAK is supposed to bring DTP to the FET table and allow high power dissipation in a smaller package than the 70N02.