Designing microamp-level systems can be interesting. From http://www.ganssle.com/rants/leaks_and_drains.html http://www.ganssle.com/rants/leaks_and_drains.html

Designing microamp-level systems can be interesting. From http://www.ganssle.com/rants/leaks_and_drains.html http://www.ganssle.com/rants/leaks_and_drains.html : I put one of the boards under a microscope and looked at some of the ancillary parts. There's a 22 uF decoupling capacitor. No real surprise there. It appears to be one of those nice Kemet polymer tantalums designed for high-density SMT applications. The datasheet pegs the cap's internal leakage at 22 uA. That means the capacitor draws a thousand times more power than the dozing CPU.