I have an existing Arduino based NTP server I wanted to put in a better battery backup for the RTC board. I meant to do it at the time but this was my "lockdown" project during the pandemic and parts I needed were just not available.
I have a MCP-73871 charger board that I want to connect in from an LM2596 DC/DC buck to step down 12V to around 4V for a 3.7V Li-ion 963450 Battery what has me completely baffled is that the capacitor that came with the board is a 4700 μF value but the datasheet says 4.7 μF does anyone know what value capacitor I should be using for this application?
The MICROCHIP boards here and here both use 4.7μF (installed).
Its not clear if this item has the cap 4.7μF on the pcb (no schematic), but the comments say the included (large) capacitor needs to be installed for stability.
I would but being a terrible artist, I use Fritzing for this sort of thing but strangely I cant find that board anywhere and the alternatives just don't work. If you tell me which bit your confused about I can try my best to explain
Thanks for pointing out the 5V power supply, didn't know that, I will adjust the output of my DC Buck accordingly.
OMG.
It is not my fault people were using a wrong abbreviation tens years ago. It is matter of fact that old schematics sometimes use "mF" when they mean "uF". That is why everyone uses 1000 uF instead of mF.
I apologize for my bluntness. Of course it's not your fault. I'm just so frustrated when there's an absolutely perfect (ok, that went a bit over) system called the International System of Units. Or simply the metric system. And then we see KM instead of km, msec instead of ms, just because someone thinks it looks better in the typographics of say a commercial or sports on TV.
But if I write mA and someone thinks that's microampere and they blow their board therefore, I still don't see any evilness in mA. I see only evilness in the lack of education.
Now we have SI units. I don't know the whole history of this but capacitors are surely older than SI. I have no idea who where and why started using mF for microfarad but I know it was used and I have seen schematics with this. When you meet mF you cannot be sure what that means. We cannot fix the past and all we can do to avoid this ambiguity is to not use mF. Writing three zeroes (or using fraction of F) is small cost for clarity.
Gentlemen, may I respectfully suggest handbags at 20 paces in the darkened car park of your choice or bikini jelly wrestling, challenger gets choice of flavour.
Nonstandard abbreviations were and are often used. Farad has been abbreviated "f", "fd", and "Fd". For the prefix "micro-", when the Greek small letter "μ" or the legacy micro sign "μ" is not available (as on typewriters) or inconvenient to enter, it is often substituted with the similar-appearing "u" or "U", with little risk of confusion. It was also substituted with the similar-sounding "M" or "m", which can be confusing because M officially stands for 1,000,000, and m preferably stands for 1/1000. In texts prior to 1960, and on capacitor packages until more recently, "microfarad(s)" was abbreviated "mf" or "MFD" rather than the modern "μF". A 1940 Radio Shack catalog listed every capacitor's rating in "Mfd.", from 0.000005 Mfd. (5 pF) to 50 Mfd. (50 μF)
Thats wrong on every possible level.
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