Update Oct 3: PD68 TripleDown/TripleStack - Tri-Channel Driver

I have wanted to do a driver with 3 output channels for quite awhile, but never got around to finishing it. When Dr. Jones announced his rendition it spurred me to get back to working on it. I’m hoping my version will have much of the same functionality of his, even though I won’t have his special firmware for it. This version will require tweaking the firmware to utilize the FET, it won’t work with any existing firmware right now (I’m still working on that). This is an evolutionary step forward from my DoubleDown driver. I also took the opportunity to add another feature I’ve been wanting lately: The 7135 on the top of the board has a cut-able trace and it’s own LED- pad so that it can be used for a secondary led (such as red).


  • 1*7135 on PWM from Pin5 (will need center pin cut) — For lower moon mode
  • 6*7135 on PWM from Pin6 (one might need center pin cut) — For normal modes
  • LFPAK56 Fet on Pin3 (No PWM on Attiny13) — For Turbo
  • Top 7135 can be separated to power secondary LED (instead of moon mode) by cutting trace directly under the “7135” label.
  • Pads for LTC Bleeder Resistor
  • BLF Standard values/locations for all minor components

As always, let me know what you think.

Edit 1/17/16: pyro1son and DEL were kind enough to help get a FW working for this driver (not Rev2). It is essentially BLF-A6 modified to work with the output configuration of this driver. It has not been extensively tested, but appears to work great so far. As uploaded, it is configured for testing correct driver function. You will want to change mode, turbo, and LVP settings before installing in a light. Here is the link.

17mm Rev1.2

17mm Rev1.2z
Same as above, but BR is removed to make room for being Zener-ready. Note: D1 is opposite polarity compared to the other boards.


20mm Rev1z
Same features as 17mm Rev1.1z, plus:

- 2.2mm through-hole for LED+ bypass

- 7.5mm spring pad

  • Generous 2.9mm edge clearance

Link to 19mm.

17mm Rev2
This version has a different focus. Rev1 was focused on providing the most possible control over a primary LED or controlling a secondary LED with lower current. Rev2 is more for lights that have 2 primary led’s, like the C22c or some bike lights.

As it sits, it is a FET+6 layout, basically a DoubleDown driver with 2 extra 7135’s. The FET and the 6 bottom 7135’s are on the two PWM outputs of the Attiny13a. If you cut the trace under the 7135 on the top, it separates the 6 bottom 7135’s from the FET. So you can have 2.28amps regulated for one output, and the FET for the other output. It will also work with existing firmwares, you only need to adjust mode levels to your liking. If you use an Attiny25/45/85 instead of a 13, you should be able to output PWM from Pin3, activating the 7th 7135 on the top, turning the FET side into a FET+1 side (and still leaving you with 6*7135 on the other side).

Of course this is all pretty experimental. I don’t know how the FET side will behave amperage-wise when both sides are on full.

20mm Rev2z
Same features as 17mm Rev2, but is also Zener ready, Attiny85 ready, and has eight 7135’s on the back instead of six.

TripleStack Rev2
This is the TripleStack. It has 3-channel functionality for a single output. I don’t think there is any way to use it with different outputs like you can with the other TripleDown versions. This version consists of a “bottom” contact board that holds the FET and most of the 7135’s, and a “top” board that holds the rest of the parts. You will need five 0.025” header pins to connect the two sides. The advantages to this board is that it will give you a cleaner look once installed, you can use a normal sized spring instead of being limited to a tiny spring pad, and parts were added that used knowledge from the Q8 driver to increase stability. The disadvantages are that it is harder to build (tight on space), you will need to make sure you have room in your pill for the stack, and it only has five 7135’s instead of the 7+ that other versions have.

Order Links:
15mm Top board
17mm Contact board
18.5mm Contact Board
20mm Contact Board


TripleStacks made specifically for the EagleEye X2R and X6R.

For the X2R, you just remove the top board on the original driver, get rid of the extra header pin, and solder this in its place. For best performance, you will also want to solder the big pad on the bottom to the top of the USB connector on the charger board. Headroom is tight, but the LED wire pads should line up perfectly with the holes in the shelf. If you order from Oshpark, be sure to get the thinner 0.8mm size. Also note the FET is the smaller LFPAK33 size.


For the X6R you will also use the stock pins. You will run ground wire from the charger board to the pad/via by the FET. The LED+ hole is over a spot you can carefully drill through the charger PCB to bypass the spring/PCB. I’ll illustrate all of this with pictures once I finish my X6R mod. Also be sure to order this one in the 0.8mm size.

I’ve been looking for weeks to find a driver with some power that can control two nichia 219 on one channel and one xpl hi on the other. Idk if this driver would qualify?

Well it wouldn’t be perfect for that. Either your nichias or your XPL would be limited to 380ma (or maybe 1140ma if you can stack 3 chips on top). That being said, I don’t know of any other real options right now.

Nice!! This is just to one LED output though, is this correct? Obviously it can drive LEDS in parallel but not separately, unless there's a way to cut/jumper mods to do that?

The white line directly under the “7135” label is a cut point to separate the top 7135 from the other 6.

Looking good! I’m hoping to get more time for this in the new year. I’ve got plenty of projects, which always seem remarkably similar to yours :wink:

Thanks for your work!

Maybe this could be a replacement driver for my SWM C22? Would it be possible to control the 2 LEDs with one eswitch? I don’t like the UI but the light itself…


PD...Please forgive my ignorance....

Is this 3 channels 1 emitter? or...

3 channels 3 emitters?

It’s definitely possible to control 2 with one switch, someone would just have to write the FW for it. Unfortunately that’s not really in my skillset.

Bugsy: 3 channels, 1 or 2 emitters

Yeah...well...you know someone that can It would be worth putting together a couple samples to send for R&D

I've been trying to understand it as well. I've been analyzing the layout, and PD's reply to my question above. The default layout of this board is like a FET+1 driver -- drives only 1 emitter, but instead of 2 paths the MCU controls for the LED output (a 7135 and a FET), there are 3 paths: one single 7135, a bank of 6 7135's, and 1 FET.

The limitation we have to work around with the ATMEL tiny MCU's is that we can do PWM's on only 2 output pins, but with PD68's design, the FET is simply switched ON or OFF with no PWM's because you don't need them. You can use the bank of 7135's for all the in-between modes, and use the single 7135 for the lowest modes.

My preference for a mode set is 5 modes w/moon, so in the Narsil firmware, you choose a 4 mode set plus you turn on moon, so modes are as follows:

Mode 1 (moon): 3 or 5 PWM value on the 7135

Mode 2 (~2%): 30 PWM value on the 7135

Mode 3 (~10%): full output on the 7135

Mode 4 (~40%): 80 PWM on the FET

Mode 5 (100%): full output on the FET

So you can see from above, the first 3 modes are actually on one 7135, and the top two modes are only on the FET. TK's spreads it out, sharing the 7135 ad FET through the mid range modes.

So on this triple down driver, if I wanted to implement my 5 modes on it, I'd use the bank of 7135's only for mode 4. Six 7135's is 2.1A, so that would be 42% for a 5A max FET. However, as you know max amps on a FET varies based on the LED, cell, cell's charge level, etc., so these percentages will vary. The 7135's will give you something more solid, but still at some point, 2.1A will not be achievable depending on Vf of the LED and power/charge of the cell.

The advantages of this implementation is we are getting very efficient on all modes because PWM's on a fully open FET is pretty inefficient - it's more wear/tear on the LED by cycling 5A at a high rate, you get the tint bias for the 5A, and lumens/amp ratio is down. I can even see using only 5 7135's instead of 6 to get closer to a 35% level for your next level below hi/max. Another thing is you can treat using a full output on the 7135 bank as your hi mode, and implementing the full FET as a turbo. We have a lot of flexibility here with the 3 channels of output and can achieve very close results to a true non-PWM driver, like the LD-1/LD-2.

I have no problem with sending a R&D sample, but I would want her to express interest in it first. I know she’s a very busy woman, and I don’t know if this is anything she would like anyways.

Technically it will work just fine using the 7135’s for separate outputs with existing firmware, you would just need to modify it a bit to get the FET to work.

Another application of this driver is using it exactly the same as a FET+1, but having another PWM LED output available for something like a RED LED, or battery/status indicator light. Since you can go up to 2.1A or 2.28A (380 7135's) without stacking, you can use the full bank to do all your modes accept the highest, or turbo, which is the full FET.

Since TK wrote the Ferrero Rocher firmware, she certainly knows exactly how to handle 3 output pins with 2 being PWM's. It's well within her comfort zone I'd think, but interest/time of course is an issue.

Correction ....2 coders ;)

Not trying to commit anybody to anything but the skills you all possess just amaze me.

Pyro1son had been working on using Pin3 output at the same time I was working on my Olive S6 and almost had it working, I think he just got busy with life. I don’t think we will even need a new firmware, just modify one like blf-a6. We already have shortcut codes for turbo and strobe, etc. We just need a shortcut code for Pin3 and we’re done.

Just finished cleaning up some very minor things on the board. Link is updated.

Since Tom stared at the circuit for awhile and didn’t spot any errors, I’m going to go ahead and order some.

Edit: 20mm and 19mm added to post 1.

I still wish there were a good driver and firmware for a true two channel and two output driver. I have a number of projects that would benefit from this. Right now I have a bike light that needs a driver to power two nichia 219s on one channel and one xpl on the other. Ild like to drive them all at around 3.3amps on hi from four 18650s. But I just don’t see this kind of driver out there…

SmileCool - Didn't think my stare was worth much. I can follow it - just noticed your comment, so spent a couple more mins on it - looks good to me..

  • the C1/D1 order is fine
  • R1/R2 voltage divider circuit looks ok
  • the OTC pad connected to pin #2 is fine - doubles as an e-switch pad
  • the Bleed Resistor I understand you need for the lighted tailcaps - all good
  • just wish you could have fit the extra cap after the diode and close to pin #8 (Vc pin). I'm rigging up a 0.1 uF cap across the Tiny85 MCU between pins 4 and 8 for now. It's the only solution I know of - the problem it fixes is happening more regularly now on the wight FET+1 drivers, so I'm doing it on all of them now. When I saw it working fine on one light til I tried a LG MJ1 cell, got me think'n it's very borderline. The MJ1's are not even a top high amp cell. I think Richard will either confirm or find a better solution - he's the only one I know of now that has the methods/tools/interest to do so, but there probably are others.

It's really not difficult to do, just takes time/effort/interest, and enough board space, which you may have in a bike light. Or you could do it manually now for sure with a couple of 7135 'farm' boards. You would wire up the two PWM output pins from the MCU, pins 5 and 6, to the slave 7135 boards, where you could have 9-10 7135's on each (9 would be 3.15A, 10 would be 3.5A). There's probably been similar projects done on BLF with a Tiny13A based board, either OSHPark custom or a Nanjg.