Today’s portable products have conflicting requirements on the batteries that power them. More features increases energy requirements, while end users demand longer battery life, so, energy efficiency is paramount. The traditional approach to minimizing energy consumption has been to minimize current drain; however, the energy capacity of a battery is dependent upon voltage, current and time. Microcontroller-based systems powered by user-replaceable batteries can benefit from an MCU that is specifically designed to address each of these variables to achieve meaningful improvements in overall energy efficiency.