After a lot of driver messing I recognized an unseen tiny debris short-circuit between C15's body and terminals, the capacitor next and in parallel to R12. That was the cause for the random/instant low voltage warnings. :facepalm:
R11/R12 divider works as it was supposed, thus R11<R12 for lower than 3V cut-off.
The one that Schoki was working on, I believe it is the same one that MTN Electronics is selling. My understanding is that it was supposed to be available to get DIY boards from OSHPark at some point, and since MTN is out of stock, and has been, it would be nice if we could get the boards to work on if we are comfortable with doing that.
Sketched out the schematics of the BW-ET1, for those interested.
I hope it’s readable.
So they built a buck-boost converter by daisy-chaining a TPS61021A (boosts to a fixed voltage, 3.3V I think) and a TPS62095 (steps back down to current set by op amp). A small dedicated 3.3V boost converter feeds the µC in AA operation.
The op amp operates more like a comparator that compares the voltage drop across the sense resistor against a filtered PWM output from the µC. No direct feedback, no fixed gain, the converter itself is the feedback loop. (I kind of understand how this works, but I’m no EE guy).
The CC control scheme looks solid but Blitzwolf messed it up with bad PWM.
Efficiency isn’t going to suffer much from this arrangement I think since the buck converter achieves around 95% efficiency. The obvious downside is driver size (humongous).
I’m looking for information regarding the H1-A driver. Maybe someone can help me here.
I don’t know which revision i have. It should be fairly up to date as i bought this driver in november 2018.
a) Does the H1-A feature thermal shutdown?
b) What would be the maximum operating temperature for the H1-A?
Looks good but better wait for it to be on sale, right now it is twice as expensive. :facepalm:
The H2-C is a proven nice option and can be modded for lower voltage output and higher current. Or use it with 2S input and 4S output, it should handle pretty hefty power that way.