Well, yes - for all 25/45/85's, might even be a benefit for 13A's. Not sure yet if DEL settled on final values of the caps and resistors though.
Only difference might be in the FET area - we are testing only with the SIR800DP, which I think all mods would equally apply to the SIR404DP (higher performance). For the other FET's, not sure, but can't hurt.
For us typical none EE's, it's hard to understand and justify at first. I've built 25 and 85 drivers where things seem to work ok, then seems like same exact build again, and it doesn't work - sometimes the resistor of FET gate to grnd fixes it, sometimes boosting C1 helps, sometimes I need to add a C2 (0.1 uF cap) to fix it. Then again, I'm not doing any of the testing DEL has done of worse case scenarios - high amps, low PWM values, etc., temperature checking of parts, plus the wear+tear part lifetime issues we can't easily test at all.
When the circuit results in spikes that are out of tolerance of part specs in the design, I guess it comes down to rolling the dice -- can you get an acceptable failure rate in mass production? WIll you get a decent life time of usage? Will you be creating a lot of unexpected heat? Will suddenly a new batch from the manufacturer be more sensitive to these out of tolerance voltage spikes than previous batches?
We run across bad drivers on occasion, and assume it's one of the parts, but could be the parts are 100% good, just that one part is more sensitive to bad spikes, or the particular traces or reflow on a board is making the bad spike even worse.
We removed the zener from our latest layout - we (DEL ) feels confident it's not needed now. For the rest, DEL would be better than I to provide feedback. He had PD68 do some tweaks on the layout, but not sure how that looks in a schematic. For example, where traces need to be beefier and/or shorter, etc.
Ohh - but the 7135's can take the 2S? Can't recall when/where/who, but thought someone said they can't take the higher voltage well. Of course you could go 2S and just not use the single and bank of 7135's in the firmware, and drive everything via PWM on the FET, but not sure if PB4 can support PWM?
They can technically take it if well heatsinked but in practice they are generally limited to around 25-30% duty IIRC I figure I can either just not use them or use them for moon modes ect.
Although the driver is mostly aimed at 1s setups. I more just want a single driver that does it all so I can order several and keep them on hand for any and all projects that may come up later.
By having a zener, 7135’s and FET I cover basically all the options and can build them to suite each case that comes up.
Yeah, PB4 can support PWM, at least it is doing so in Bistro, which is the firmware this will be running.
Anyone have experience using 0603 or 0402 components in drivers? I think I could figure out how to get it all on there with 0805 but it would not be as efficient (aka more vias and no room for a pass through).
I think you got it. No difference for clicky or eswitch, except maybe larger R1/R2 for eswitch.
Suggested part values are up in this thread somewhere: post
You can get away without either C1 or C2 if space is tight (it is amazing what we have been getting away with before). If C1 is taken out, C2 needs to be up-sized to a few uF. It is a compromise: For greater integrity of the MCU power supply, keep C2. For more accurate/easier ADC input and firmware manipulation, keep C1.
See how the CAD software shows pins 4/8 together? - That is partly to make the decoupling circuit more obvious…that is where C2 should be shown and eventually routed.
Similarly R1 should be routed directly off C1 (or C2), there are ugly things on the Cell±R5-C1-GND line. (Though you will have to run the ADC in 10-bit mode to see the difference.)
So I think these are the changes you are referring to? Far from an expert in circuit design myself, just have a reasonable understanding of how it works once together and how to actually put it together.
It is proving interesting trying to fit everything on the board at all, is it better to leave out C1/C2 and/or R4 and place them in the “ideal” location or to leave them in and put them wherever it will fit?
My gut says leave them in and put them wherever they can fit. Which won’t be like the schematic based on how tight things are as is.
Ohh - bout the 0603 and 0402 parts, I've used 0402's, but just one, on Richard's new MTN-17DDm driver - didn't have any problems. 0603's are not bad - still readable markings, and ok to reflow.
That is close. On the PCB pin 4 should route to C2 and C2 then on to ground. Similarly pin 8 should route to C2 and C2 then on to D1.
If I had to use only one C, it would be C2 (= 4.7 or 10 uF). Remember then to account in firmware for the D1 voltage drop when you do voltage indication or step-down. On a small board C2 is probably be the only critical component re. location. It should be right up against U1 and the tracks to pins 4, 8 very short.
You can get away without R4, but the switching noise will be larger. May or may not give issues, depending on the layout and build.
Here is how the board sits right now (still a work in progress, but no need to polish it up if I have to make major changes), I managed to fit it all on there with 0805 components but just barely and just enough room for a 2.5mm pass-thorugh for the spring.
It is hard to read the board from the pictures since I do not have the silk screen done yet and it is very sloppy as it sits now. The silk screen that is there now are set just above the component they are designating.
The biggest thing is that grounding C2 to pin 4 had to go with a .26mm trace in order to fit under the R4/R3 resistors.
I went ahead and cleaned up the silk screen some to make it easier to read. Polished up a few areas as well but left the copper pour off to make the circuit easier to understand.
I am sure I forgot / messed up with the credits silk screen, honestly being pretty new here so please let me know if you think it needs any changes. Or if there is anything else that I should find room to silk screen onto it.
Good point, didn’t even think of that, it is so easy to forget how small these things are dealing with when they are staring at you on a 24” screen lol.
I am using Diptrace for the schematic and PCB design, it is great since you can make a change in one and directly import it into the other.
Ok, decided to change the plan of attack somewhat. I want to say that PD68 you did a great job on these drivers and I fully admit to blatantly ripping off your idea and DEL’s circuit in these drivers, I take no credit for these at all. Oh and Toykeeper is 100% to thank for the firmware.
I started making a 17mm driver with the same setup so that I could have matching drivers for all the major sizes of 17mm, 20mm, 22mm and on up ect.
To get it all on the 17mm board I had to use 0603 components and remove 2x 7135’s. Otherwise it is the same setup. I figure I will just use 0603 for them all since I will need to buy new components anyways and the 0603 is cheaper anyways. From reading online the 0603 doesn’t seem much harder to work with either.
Oh, I managed to fit the bleeder resister onto the 17mm PD but it had to be an 0402 package. It will be 0603 on the larger ones.
So here is what the 17mm driver looks like, if this gets DEL’s and everyone elses go ahead I will make the 20 & 22mm versions and then order a few to test. I can also post up the source files if anyone wants as well
) feels confident it's not needed now. For the rest, DEL would be better than I to provide feedback. He had PD68 do some tweaks on the layout, but not sure how that looks in a schematic. For example, where traces need to be beefier and/or shorter, etc.
