I have a DS3231 RTC in my circuit design. I have not included the 200R and in4148 as usually included in the RTC modules, as this is apparently a bad way to charge the LIR2032.
I could use a standard 2032, but I would like to have a rechargeable option (yes, I know... the RTC will take years to run down the standard 2032).
The Vbat pin on a DS3231 can take 2.3v - 5.5v, so a 3.6v NiMh would seem suitable (and I have loads of them).
But, I cannot find a suitable circuit to run from 5v to charge the battery. I hunted around the RS site for battery management IC's, but they are biblically expensive (£8 ish) and not exactly what I need.
Anyone have an ideas or at least a basis on an approach?