Reminds me of the development of a battery powered medical device I did about 7 years ago. We selected an esoteric Freescale microcontroller for that project (w

Reminds me of the development of a battery powered medical device I did about 7 years ago. We selected an esoteric Freescale microcontroller for that project (which was successfully used in such applications before), but for the life of me I couldn't get the power consumption in deep sleep to come anywhere near the spec (few microamps IIRC). Eventually, after scanning the datasheet forward and backward again and again, I had this idea which turned out to be the right answer: microcontrollers usually come in several package configurations, each with a different number of pins. Freescale used the same silicon die in all of the variants of that microcontroller, and left unrouted pins floating internally. I had to write to registers which, on paper, didn't even exist on this processor variant to put all I/Os in a defined state. The power consumption then came within the spec.