New Driver: PD68 "DoubleDown" - 17/20/22mm FET+4

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pilotdog68
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New Driver: PD68 "DoubleDown" - 17/20/22mm FET+4

New Driver: PD68 “DoubleDown” – 17mm FET+4

Whenever I am modding a light, it is always a struggle for me to decide if I want the all-out power of a FET driver, or if I want the consistency of a Linear driver. If I choose the linear driver, I then have to mess with stacking 7135’s to get the high mode where I want it.

To make things easier on myself, I decided to mix the two of them. Medium is my most-used mode, and for me the sweet spot for medium is always in the 1-1.5amps range. This driver will let you stay in regulation for moon, low, and medium, then access the FET for the highest mode. It will also function as a normal single-sided FET+1 driver if you don’t populate the pads on the back.

I wanted room to fit a 7.5mm spring, so the 7135’s on the bottom are pushed out a bit. This could cause retaining-ring issues, but it was a sacrifice I was willing to make.

I also included pads for a Bleeder Resistor for my Lighted Tailcap project.

The design is heavily influenced by wight’s designs, and others helped answer questions along the way.

This is my first time at making a driver. So if you see something that looks off, please let me know. It is untested as of now, I just placed the first order.

17mm Revision 2 and 2.1 (Current)
Revision 2.1 is the same as 2, but with the MCU and FET pushed more outwards to accommodate a 2.1mm pass-through for an LED+ wire.

20mm and 22mm Revision 2.1 (Current)
These boards are identical except for the outside diameter. They have all the same features as the 17mm board, plus:

  • LED+ hole is now directly in the center
  • Attiny45/85 ready
  • Separate pad for Pin 3
  • Zener ready
  • Gate pulldown resistor for FET

Oshpark link for 20mm ……………. Oshpark link for 22mm

My Favorite Modded Lights: X6R, S8 , X2R , M6, SP03

Major Projects:  Illuminated Tailcap, TripleDown/TripleStack Driver

Edited by: pilotdog68 on 11/06/2015 - 21:16
pilotdog68
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Revision 1 (Outdated)

My Favorite Modded Lights: X6R, S8 , X2R , M6, SP03

Major Projects:  Illuminated Tailcap, TripleDown/TripleStack Driver

ImA4Wheelr
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Looked it over.  Assuming your using Attiny13a (SSU footprint?), it looks good to me.  Nothing is jumping out other than the not connected ground pad (as you noted).  Nice work there!  Wish I was as handy as you with Eagle.

bugsy36
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Fantastic!!!!!! I do not know anything about designing the drivers but I sure as hell am extremely happy to see others continue on Wink

One question...instead of an Attiny13...can you get a 25 to fit. Thinking of TK and others with the talent to write code that can do tricks...especially silly code for flashlights LOL

It's the simple things that we take for granted that cost us the most

Ευκαιρία λέει πιάσε με από το μέτωπο γιατί μόλις έχω περάσει δεν θα με πιάσειs

pilotdog68
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well this one will just be with the 13a because I personally don’t expect to upgrade to the 25 anytime soon. I don’t think I can get the 25 on here, but maybe when I get the physical boards from oshpark I’ll be able to see where I can make up some space.

Edit: wait, doesn’t the Attiny25 come in the SOIC8 package? I was thinking about the 45.

My Favorite Modded Lights: X6R, S8 , X2R , M6, SP03

Major Projects:  Illuminated Tailcap, TripleDown/TripleStack Driver

pilotdog68
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ImA4Wheelr wrote:
< Nice work there!  Wish I was as handy as you with Eagle.

Thanks. I don’t know if I’d call myself “handy” yet; it’s been a frustrating 6 hours. Tired

My Favorite Modded Lights: X6R, S8 , X2R , M6, SP03

Major Projects:  Illuminated Tailcap, TripleDown/TripleStack Driver

pilotdog68
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the main things I’m worried about:
Is the voltage divider correct?
Do I have enough/correctly placed via’s?

I’m working on moving stuff in a bit more away from the edges

My Favorite Modded Lights: X6R, S8 , X2R , M6, SP03

Major Projects:  Illuminated Tailcap, TripleDown/TripleStack Driver

ImA4Wheelr
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Voltage divider looks good.  I can't answer your concern for the via's.  I'm sure there are formulas to determine how many and how big they need to be to handle the current they will be moving, but I'm not knowledgeable in that regard.

Rufusbduck
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I believe 3 pins on the FET are ground and since all the current passing through the FET goes to gnd I’d suggest grounding all three with a pour connected to the ring. TP would slap you upside the head for running the pwm trace under the 7135’s and three pads on the gnd ring have acute angles.

Three Tanna leaves to give him life, nine to give him movement. But what if he eats the whole bag?

Scott

pilotdog68
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what exactly is wrong with acute angles? I am adding a big silk under the 7135’s, both for aesthetics and to help insulate the pwm trace.

My Favorite Modded Lights: X6R, S8 , X2R , M6, SP03

Major Projects:  Illuminated Tailcap, TripleDown/TripleStack Driver

Rufusbduck
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The 7135 output trace should be wider(as wide as will fit) as this is part of the heat sinking of the chips as well as the current bus. Eliminate the doglegs in the pwm trace to pin connections. It’s fun puzzling out how to move stuff around isn’t it?

Three Tanna leaves to give him life, nine to give him movement. But what if he eats the whole bag?

Scott

Rufusbduck
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Since there’s nothing in the way you could make the spring pad a bit smaller but connect it to a copper pour under the led+ pad with vias there to make up for anything lost under the mcu. This would allow you to move the bottom side 7135’s inward and give more room for ground tabs to clear a retainer ring.

Three Tanna leaves to give him life, nine to give him movement. But what if he eats the whole bag?

Scott

pilotdog68
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I really want a 7.5mm spring pad so I don’t have to use those teeny Qlite springs. I actually wanted 8mm, but that wasn’t feasible.

I think it’s done, but I can’t figure out how to crop the workspace size… its a big mostly empty square on oshpark

My Favorite Modded Lights: X6R, S8 , X2R , M6, SP03

Major Projects:  Illuminated Tailcap, TripleDown/TripleStack Driver

Halo...
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Rufusbduck wrote:
I believe 3 pins on the FET are ground and since all the current passing through the FET goes to gnd I’d suggest grounding all three with a pour connected to the ring.

Yea, you want a thick wide connection to the fet ground pins to keep resistance low.
pilotdog68
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I’ve fixed almost everything you guys have pointed out, thanks. Now I’m having the issue where oshpark renders a big empty square with the driver down in the corner. What’s the fix for that? other than that, the driver is done.

edit: like this

My Favorite Modded Lights: X6R, S8 , X2R , M6, SP03

Major Projects:  Illuminated Tailcap, TripleDown/TripleStack Driver

Halo...
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pilotdog68 wrote:
I can’t figure out how to crop the workspace size… its a big mostly empty square on oshpark

Check if you have any parts, traces or silkscreen somewhere outside your board, Oshpark automatically crops to the smallest square that fits everything.

~ edit ~
Can’t see your picture.

Less likely imo but it could also be a problem with you cam job. Oshpark provides a cam job here.

I don’t see anything that should be a problem from your screenshot.

pilotdog68
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Thanks for the help guys, I’ve changed most of what you suggested and cleaned stuff up a bit.

OP updated

My Favorite Modded Lights: X6R, S8 , X2R , M6, SP03

Major Projects:  Illuminated Tailcap, TripleDown/TripleStack Driver

Halo...
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If you can’t find anything that could be causing the problem then I could take a look at your .brd file. You can add the .brd to the zip file that contains your gerbers, upload to oshpark then share. Oshpark just ignores extra files in a zip, it only uses the gerbers when a zip file is presented.

~ edit ~

Opps. Shocked Looks like you fixed it.

pilotdog68
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Halo… wrote:
If you can’t find anything that could be causing the problem then I could take a look at your .brd file. You can add the .brd to the zip file that contains your gerbers, upload to oshpark then share. Oshpark just ignores extra files in a zip, it only uses the gerbers when a zip file is presented.

~ edit ~

Opps. Shocked Looks like you fixed it.

Yep, it was the dumb limit box eagle makes. I thought I had deleted it, but apparently I only deleted one layer of it. All is well now

My Favorite Modded Lights: X6R, S8 , X2R , M6, SP03

Major Projects:  Illuminated Tailcap, TripleDown/TripleStack Driver

chouster
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Looks nice. Thanks for the effort and for sharing, pd68, you continue to amaze with nice innovations.

To me the 7135 pads on the bottom look pretty close to the spring pad, but I’m far from beeing an expert, and I understand why you wanted the spring pad as big as it is.

pilotdog68
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I’m no expert either, but after getting some sleep, I have found a few little things I will change. A revised board will come later today.

My Favorite Modded Lights: X6R, S8 , X2R , M6, SP03

Major Projects:  Illuminated Tailcap, TripleDown/TripleStack Driver

Rufusbduck
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Acute angles like the one at the gnd ring of the OTC can cause acid traps and result in poor rendition of the board or at least so I’ve been told. Acute angles become places where the copper might get over etched resulting in a broken trace. Try thinking in terms of removing a minimum of copper to create the traces and separations and you will be headed in the tight direction.

Three Tanna leaves to give him life, nine to give him movement. But what if he eats the whole bag?

Scott

pilotdog68
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Guys I really do appreciate all the comments and tips. Keep ‘em coming!

I think I got rid of all of the acute angles now. I also:
- added more ground via’s
- moved the bleeder resistor (for lighted tailcap) to the top
- increased the copper pour size for the FET ground connection
- retooled the spring pad area and silk screen.
- widened all led- traces to 1mm

My Favorite Modded Lights: X6R, S8 , X2R , M6, SP03

Major Projects:  Illuminated Tailcap, TripleDown/TripleStack Driver

chouster
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nice improvements, pd! You think one could drill through the board and run a wire from withinside the spring to led+ on the mcpcb? Would it even make sense to run that wire directly from the top of the spring to the mcpcb? I think I would try do that and solder the MCU on afterwards

pilotdog68
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How’s this Chouster? 2.05mm 2.1mm hole through the (almost) middle.

My 20awg silicone wire measures at 1.9mm thick.

Edit: Made some very minor changes to the hole spacing, updated pics and links accordingly

My Favorite Modded Lights: X6R, S8 , X2R , M6, SP03

Major Projects:  Illuminated Tailcap, TripleDown/TripleStack Driver

chouster
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I don’t know what the experts would say and I really would like to know, hope there’s some feedback from other guys. To me, that looks nice. I think this also would come in handy when doing piggybacked driver setups.

pilotdog68
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The driver needs it’s own batt+ connection, so for when you’re piggybacking drivers you’ll still need to connect a wire or something to the springpad.

I don’t like when the hole is the only led+ connection or when it interferes with soldering the spring to the driver, but it seems like it would be ok how i have it.

I agree, I was expecting more feedback, but then again it’s only been 4 hours since I posted Rev2

My Favorite Modded Lights: X6R, S8 , X2R , M6, SP03

Major Projects:  Illuminated Tailcap, TripleDown/TripleStack Driver

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Do you have Mattaus cam generator job? Also use I believe it’s called outline in eagle as the cutoff ring for dimensions…I see you are up to rev 2.1 at OSHPark… great job by the way, loving thes dual output builds!

pilotdog68
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I tried Mattaus’ cam, but it wasn’t working with Eagle 7.2. The support people at oshpark sent me a cam job that has been working great.

Question: when I do “hole” instead of “via” the insides won’t be plated, right?

My Favorite Modded Lights: X6R, S8 , X2R , M6, SP03

Major Projects:  Illuminated Tailcap, TripleDown/TripleStack Driver

chouster
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I think most people would prefer the look of the version without the hole, so please don’t keep it like this just for me. I like to have holes in these boards, because I think it’s easier to solder and makes a stronger connection when wires are through-hole soldered. I thought having a hole inside of the spring would make bypassing these easier, but I also like the way led4power had the led+ connection on his ld-1 driver, where the hole comes out outside of the spring.

pilotdog68
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Just to be clear, it isn’t really going to work for through-hole soldering. There isn’t any electrical connection on the top of the hole. It is just a pass through for insulated wire to go straight from the tip of the spring up to the mcpcb. Some people like that because you get less resistance from the traces in the driver.

I’ll keep both versions available.

My Favorite Modded Lights: X6R, S8 , X2R , M6, SP03

Major Projects:  Illuminated Tailcap, TripleDown/TripleStack Driver

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