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

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Rufusbduck
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Copper is pretty far from the edge. Copper not drawn past edge of board? It looks almost as if the milling line were drawn and the copper just drawn to the inner edge of the milling line but sometimes fabs don’t come out quite as intended.

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

Scott

Halo...
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Oshpark doesn’t like copper right up to the board edge. They have often moved it back from the edge on my boards. And I use very thin milling lines, 0.01-0.03mm, with my ground copper beyond the board edge. Their official specs say “at least 15 mil clearances from traces to the edge of the board”.

chouster
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So do you guys think I should contact OSH Park and tell them about these issues?

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The lack of a ground ring on the left side is a combination of two issues. 1) Oshpark does not support copper right up to the edge of the board. Must be 15 mil clearance from the edge of the board. If you try to go right up to the edge with your ground ring, they will cut it back. So this part is not error on oshpark’s side.
2) The soldermask is shifted more than usual for oshpark. This might be a legitimate defect on the fab’s part. Oshpark’s specs say “Maximum soldermask expansion, retraction, or shift is 3mil.”

chouster wrote:
Notice the lack of the ground ring on the left side and the weird things going on with the plating of most of the pads?

There might an issue with the plating but I can’t really see it in that picture. Maybe it’s just scuffed up from mailing? I’ve had scuffs of the gold plating on some of my boards.

Personally, I’d try one of the boards, if I could reflow it ok without shorts due to the shifted soldermask then I wouldn’t bother asking for a replacement.

pilotdog68
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If you are using a retaining ring (or soldering to a pill), you will have plenty of ground contact on the back side, but I personally would contact Oshpark because they are so easy to work with, and also I’m interested if they would comment on why they think it happened (maybe I can change a way I do something?).

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

Major Projects:  Illuminated Tailcap, TripleDown/TripleStack Driver

DavidEF
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pilotdog68 wrote:
If you are using a retaining ring (or soldering to a pill), you will have plenty of ground contact on the back side, but I personally would contact Oshpark because they are so easy to work with, and also I’m interested if they would comment on why they think it happened (maybe I can change a way I do something?).

Has anyone else bought any of these boards? If it was something pilotdog68 did, or failed to do, they should all show up like this, right? Would be interesting to know.

The Cycle of Goodness: “No one prospers without rendering benefit to others”
- The YKK Philosophy

mattlward
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They look fine.  I am hoping to get a 22 built this weekend, if time allows.

EDC rotation:
FW1A, LH351D 4000k (second favorite)
FW3A, LH351D 3500k
FW3A, SST20 FD2 4000k
FW3A, Nichia 4000k sw40 r9080 (favorite light!)
FW3A, Cree XP-L Hi 5A3
Emisar D4V2, SST20 4000k
S2+, XM-L2 T6 4C

chouster
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I’ve managed to build a working driver. Running bistro on it. Very very nice. Thank you Pilotdog!

pilotdog68
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chouster wrote:
I’ve managed to build a working driver. Running bistro on it. Very very nice. Thank you Pilotdog!

Sweet!

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

Major Projects:  Illuminated Tailcap, TripleDown/TripleStack Driver

chouster
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Made some minor adjustments to bistro to best suit my likings so far and I must say: what an awesome firmware she wrote!

You did a hell of a job with that driver board as well.

cbrake10
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This is probably a dumb question, but what is pin3 being used for these days?

-Clark

pilotdog68
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cbrake10 wrote:
This is probably a dumb question, but what is pin3 being used for these days?

On this board? Not really anything. The TripleDown uses it for an output.

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

Major Projects:  Illuminated Tailcap, TripleDown/TripleStack Driver

mattlward
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All of my SOD323 diodes say 47 on the top with no line on either end. I am assuming that the 4 would be on the side away from the line drawn on the 22mm driver? The anode on the diode is to the left of the label on the diode if held in normal reading position.

Diode datasheet.

I have not built the 22mm version of this driver until now.

It is going to get Bistro on a tiny25! Smile

Thanks Matt

EDC rotation:
FW1A, LH351D 4000k (second favorite)
FW3A, LH351D 3500k
FW3A, SST20 FD2 4000k
FW3A, Nichia 4000k sw40 r9080 (favorite light!)
FW3A, Cree XP-L Hi 5A3
Emisar D4V2, SST20 4000k
S2+, XM-L2 T6 4C

pilotdog68
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I used to have some diodes that said “41” and the ‘1’ was the “line side”. You can always try it, if you have it on wrong the driver simply won’t power up.

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

Major Projects:  Illuminated Tailcap, TripleDown/TripleStack Driver

mattlward
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That is the direction I thought they went, thanks for the confirmation. What diodes do you use now and is there a reason other than price? That is just for reverse polarity right? It would be much easier to install them if they were 0805 rather than those darn things with legs.

EDC rotation:
FW1A, LH351D 4000k (second favorite)
FW3A, LH351D 3500k
FW3A, SST20 FD2 4000k
FW3A, Nichia 4000k sw40 r9080 (favorite light!)
FW3A, Cree XP-L Hi 5A3
Emisar D4V2, SST20 4000k
S2+, XM-L2 T6 4C

pilotdog68
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yeah it’s reverse polarity. I actually really like the 323 package for those diodes.

I usually order the cheapest diodes that work for the application, and that usually means stuff that’s about to be phased out. So every time I have gone back to order more, I’ve had to find a different part number that wasn’t discontinued.

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

Major Projects:  Illuminated Tailcap, TripleDown/TripleStack Driver

wight
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For FET drivers it’s important to stick with reasonably low Vf on the protection diode. This keeps gate voltage as high as possible.

Still fine, still on a break. One day I’ll catch up with you folks! previous wight catchup Wink
list of my drivers & variants (A17DD, FET+1 stuff, WIP stuff, etc)

pilotdog68
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wight, can you explain the need for the higher gate voltage? Does it matter if you aren’t PWMing the FET?

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

Major Projects:  Illuminated Tailcap, TripleDown/TripleStack Driver

wight
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Sure. Gate voltage corresponds to RDS, right? The MCU drops a lot of voltage (the ATtiny13A is spec’ed at 0.7v drop I think) on it’s own. That’s after the protection diode has dropped whatever number, maybe 0.2v. Subtract that from your battery voltage – which at high drive currents is sagging.

For an example, let’s imagine a light where the battery voltage drops to 3.7v under full load. Subtract 0.2v, then subtract whatever the MCU drops (0.7v?)… so gate voltage can be no higher than 2.8v at this point. Look that up on your RDS graph and see what’s happening… we are probably flirting with poor FET performance at that point. (I didn’t go look one up while writing this.)

Still fine, still on a break. One day I’ll catch up with you folks! previous wight catchup Wink
list of my drivers & variants (A17DD, FET+1 stuff, WIP stuff, etc)

pilotdog68
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I think you may be overestimating my understanding of the subject.

I understand and can follow the voltage losses going through the diode and mcu before getting to the FET gate, but I have no idea why that needs to be above a certain level or what “RDS” is.

From reading discussions previously I somehow came to the assumption that that only mattered if we are PWMing the FET. Are you saying it always matters?

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

Major Projects:  Illuminated Tailcap, TripleDown/TripleStack Driver

wight
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Yes, it always matters. Take a look at Figure 8 on Page 7 of the PSMN3R0-30YLD datasheet. Another “telling” place to look is Figure 10 on the next page.

A minute or two looking back and forth between those graphs and the back-of-the-napkin math will likely get your mental cogs turning! :GRADE:

EDIT: RDS is the “Drain-Source” resistance, it’s very important for our applications. It must be kept as low as possible in a DD driver.

Still fine, still on a break. One day I’ll catch up with you folks! previous wight catchup Wink
list of my drivers & variants (A17DD, FET+1 stuff, WIP stuff, etc)

pilotdog68
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So let’s see if I understand this (in extremely simpleton terms). I had assumed that applying voltage to the gate pin on the FET just served as a notification to the FET like, “Hey, FET! Open the door!”.

But really, the voltage on the gate is what is actually “opening the door”? So if the voltage is too low on the gate, it will take longer to “open the door” and it might not be able to “hold the door” all the way open, causing extra resistance?

edit: BTW the graph was helpful. I never realized how close we were operating to the cliff on these voltages

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

Major Projects:  Illuminated Tailcap, TripleDown/TripleStack Driver

mattlward
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Is Rfet needed here? If so, what is the suggested value?

Thanks Matt

EDC rotation:
FW1A, LH351D 4000k (second favorite)
FW3A, LH351D 3500k
FW3A, SST20 FD2 4000k
FW3A, Nichia 4000k sw40 r9080 (favorite light!)
FW3A, Cree XP-L Hi 5A3
Emisar D4V2, SST20 4000k
S2+, XM-L2 T6 4C

wight
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I thought it would be. We are that close to the cliff!!

You are correct, the voltage is “holding the door open”. We never get the door 100% open (zero resistance), but we can achieve very low resistances. As has been pointed out to me in the past: at low battery voltages the resistance becomes a moot point because we don’t have enough voltage to drive the LED hard anyway. Ideally I’d like to see decently high drive currents through 50% to 75% of a battery if possible. I’ll certainly take whatever I can get, but a lot of that depends on the LED Vf in most cases. At a higher drive current the problem is exacerbated. I’m not sure how that fits in to the “door” analogy, but it doesn’t really need to – you get the idea.

Eyeballing that “knee” in the graph is one of the things which motivated me when moving the battery voltage divider. Measuring “before” the protection diode means that we can put in whatever diode makes sense without having it drastically affect voltage monitoring.

Your assumption is a common one. I have made the same assumption in the past. An FET seems a lot like a solid state “relay” but it’s really not very similar at all. What a letdown, right? Carefully looking over those graphs is what makes DD FET selection take forever.

Home work: OK, I kept this one in reserve. It’s an easy assignment, don’t worry. Now that you’ve achieved a handle on this concept… go lookup the same graph in the SiR800DP datasheet.

Still fine, still on a break. One day I’ll catch up with you folks! previous wight catchup Wink
list of my drivers & variants (A17DD, FET+1 stuff, WIP stuff, etc)

pilotdog68
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wight wrote:
Home work: OK, I kept this one in reserve. It’s an easy assignment, don’t worry. Now that you’ve achieved a handle on this concept… go lookup the same graph in the SiR800DP datasheet.

Well that explains why some people love it. Still not sure if I’ll jump to using it though, it’s a whole $1 more! Big Smile

Thanks for the education. :GRADE:

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

Major Projects:  Illuminated Tailcap, TripleDown/TripleStack Driver

Tom E
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a $1 more? Where? Not from Richard: $0.80 —> $1.35, or am I missing something?

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Received my boards today looking good PD

wight
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Tom E wrote:
a $1 more? Where? Not from Richard: $0.80 —> $1.35, or am I missing something?
Looks like there’s about an 80-cent difference per piece when purchasing QTY=10 on Mouser or Digikey.

Still fine, still on a break. One day I’ll catch up with you folks! previous wight catchup Wink
list of my drivers & variants (A17DD, FET+1 stuff, WIP stuff, etc)

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Will the parts from a Banggood A6 driver work on this board?
If not, how can I get a controller that is already programmed?
(After using computers heavily for almost 50 years I don’t feel like learning how to load the programs in another system.)

Flashlight designers should look at lighthouses and pottery.
这些谁设计的手电筒应该看灯塔,以及在陶器。

mattlward
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Just finished the basic build on the 22mm version of this board, it caught me by surprise with a new set of pads called Rfet. I did not populate it because I am not using the Vishay FET, I am using the standard LFPAK56 FET on this build. From reading many threads, it appears that the Vishay FET has a better state of high conductivity/lower resistance during a nearly fully driven state and it was causing the issue with the full to moon flicker. I also did not include it because I could not find a reasonably solid value for that resistor, it looks to me like 12k ohms might be the desired value with the Vishay… Do I need something on the pads for the driver to work? I could use a little guidance here, looking at the board layout, it looks like it is optional with the traces in the area of the FET.

Anyway, on to the board! I think I am finally getting the hang of building these well the first time. I have simply been using to much solder paste. I think this is my best build yet! Smile

!2016-02-24_08-00-44!

Matt

EDC rotation:
FW1A, LH351D 4000k (second favorite)
FW3A, LH351D 3500k
FW3A, SST20 FD2 4000k
FW3A, Nichia 4000k sw40 r9080 (favorite light!)
FW3A, Cree XP-L Hi 5A3
Emisar D4V2, SST20 4000k
S2+, XM-L2 T6 4C

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