ATTiny13A based drivers w/ off-time memory issues (operating as NEXT MODE memory and activating mem when it should be off)

I've started having a few memory related issues with some of my 13A based drivers running STAR off-time. I'm actually having 2 issues, first is the other day my S6 triple with a BLF17 DD V1.0 (which has always had memory disabled in the FW (commented out) since I built it and worked perfect) all the sudden started operated as if it had next mode memory. I tried reflashing it several times, I also changed out the off-time cap thinking it went bad, I even swapped the MCU, NOTHING HELPED! I had to end up building and swapping in a new driver with a brand new MCU, the old driver is still doing it on the bench today.

I'm having very similar issues with wight's 22mm 16x 7135 driver but it never worked with off-time (wasnt aware at first even tho I was running 2 of these drivers, one with a momentary FW and the other with LUXDRV, once I switched to STAR off-time it started right away and nothing helped get it to act normal, I would be happy with either memory off or functioning as intended but again it act's as if its next mode memory, this one is strange tho, if you leave it set for a day or so the memory will reset (memory disabled in the FW) and it will start on moonlight as intended but ONLY if you let it set ~24hours, other than that it's next-mode. (note the S6 may have reset given enough time but I didnt wait to find out, its my EDC)

Finally the most recent one was a 17DD_V1.0 I have in a ZY-T08 running an SST-90, again this one has next-mode memory and again if left set overnight it will revert back to the start but the difference here is this one has memory ENABLED in the FW.

My first thought is an EPROM issue, possibly something related to wear leveling but I have no clue plus swapping in a known good MCU and 1uf OTC onto the broken S6's driver did nothing, it literally made no change, I dont see how it couldnt have helped...

Just so you can see I’m not crazy here is a <1min video showing the two lights operating as if they have NEXT MODE memory. The E21 should start on mode 1 after the reset, the T08 should start on mode 3 (mem enabled). Also I’ve tried running them both for longer periods to “set” the mode (up to 20min), nothing helped.

Try lowering the off time limit in fw. Happen to have caps under 1uf?

So its off-time mode switching but no memory (still uses an off-time cap)?

yeah…it’s a click to the mode you want…but if you shut it off for a little bit, it will default back to the starting setting

I've built a bunch both with and without memory and found no problems. The only thing I can think of is if the ground side of the cap somehow isn't an actual ground (solder floating/not bonded well), or capacitor damaged from too much heat when soldering (it's not impossible that replacing a damaged cap with a new one wouldn't fix it, if the new one is damaged by too much heat when installed also).

Suggestion for heat setting on reflow gun?

I have an 858D, use 310-320 on the temp and 3-3.5 on the air. I have no idea if the actual temp has any relation to the actual, though. If I set it lower than that it takes too long and the time the heat is applied matters too, not just the temp.

I had next mode behavior on a nanjg flashed with off time firmware but forgot adding the capacitor…

I had a similar problem on a BLF17DD that I built a while back. It was playing up sporadically, & was working in ‘next-mode memory’.
I was trying out the updated location of the CAP that eliminates the over-current spikes to the MCU.
I ended up moving the CAP back to the original position on the board, & the problem went away.
I never pinned down what caused the problem, but I’m guessing it was to do with either the CAP it’s self, or a bad solder joint of the CAP.

You had some other issue we could never get to the bottom of, relocating the cap (C1, not the off-time cap) flat out works, the only way for it to not work is for something to be wrong somewhere.

Yep, that’s why I suggested that my CAP was either faulty in some way, or I had not soldered it properly.

C_K has mentioned he’s changed the off-time CAP, but not the CAP at C1.

I didn’t try changing the C1 cap but all the 17 boards (v1.0’s) are the new version with the new cap location (the 16x7135 is to the new style but didn’t seem like the 7135 drivers needed to have an update).

My reflow settings are 315* at 4.5-5 air settings, I hold the air on the component 15sec max if it doesn’t work I give up and remove/reapply solder and try again after it cools.

I still have the assembled driver removed from the S6, I’ll start working on it replacing C1 first to see what that does, OTC setting is stock @ 130, what direction would I move to lower the time?

FWIW I never had this issue on any of the 50+ old style BLF DD drivers I’ve built, only the new ones, I’m glad I had so many extra old style ones, I’d hate to send one of these to a customer. Also why I ordered these in soon as they came out and installed them in all my personal lights.

Solder joints are all for sure good, 1 (not to sound stuck up) but I’ve gotten really good at soldering recently and 2 I chance nothing, before I try powering anything up the first time I test every solder joint with a DMM for continuity, especially the OTC testing for short to pins 1&3 and verifying the cap it’s self isn’t bad and just a sort to GND.

Just to clarify, I wasn’t suggesting that the location of the CAP was bad, just the possibility of a bad joint/CAP.
Interested to see how the board from the S6 turns out.

That's exactly what I was thinking as soon as I read your initial post: are you using the new capacitor location? Now that we know that's the changed variable, the next step is looking for the solution, which hopefully is as simple as finding a new threshold value.

I found out early on that the off-time timing is sensitive not only to the 1uF capacitor on the pin, but also the main capacitor powering the MCU. I built a batch of boards where I inadvertently put 1uF capacitors where I normally put the 10uF...none of them worked right until I swapped the 10uF back in.

The easy solution would be to put a scope on the off-time capacitor and see what's going on timing wise....the other solution would be to start playing with the off-time threshold values to see if you can get something to work.

I'm still running the old style boards and "slow" 9.4khz PWM...I guess you could call me old fashioned!

It could be the caps you are using. SMD caps are evil little creatures. And the smaller their physical size and the closer they are run to their working voltage spec, the more evil they become. For instance, a 10uf 6V cap might actually act like a 1 uF or smaller cap if run at 5V. What you think are 1uF caps may be acting like 0.1uF caps… I always use the biggest package/highest voltage rating caps that I can fit on the board.

Also, note that capacitor values can change over time. Some dielectric types are particularly bad… avoid the cheaper/more unstable dieelectrics if a stable capacitance value is important. For instance X7R caps can be spec’d at +80/-20% values as shipped from the factory… and can get worse from there…

Which is the correct cap voltage for off - time memory?

Just measure it zere. Think what Texas is trying to say is, get the biggest quality cap you can find and stick it in there. The voltage doesn’t have to match, long as it’s higher than what your putting in.

I didn’t get to this today unfortunately, I have the old S6 driver sitting out on the bench waiting, even got a 10-pin ribbon cable with flying leads soldered on for programming over and over trying to mess with the values (what direction should I start moving?) but I didn’t get to sit down and actually try anything today.

Is there some way to measure cap’s? The ones I’m using are all known value and all come from new tapes so I can’t imagine they’re bad but if there was some way I could test them that could maybe help some.

The part I've been using for the off-time function is 0805, 1uF, 10v, 5%. Not had any issues with them. Even with a higher-Vin zener-modded driver there will never be more than the MCU's Vcc voltage available at the off-time cap, the MCU gets unreliable over 6 volts. So if the MCU is still working the 10v-rated OTC will never get more than 6 volts.

I think the one I used in the Digikey shared carts is the same as above, but 16v.