Accounting for all of the obvious points of power consumption and their current levels for active and sleep states can be a difficult task. In every design there are also points of power consumption that are often overlooked. Every type of semiconductor device has some amount of “leakage current” that may or may not be called out in its datasheet. Leakage current can make up the majority of the deep-sleep current draw for a modern micro when it shuts off power to most of its internal circuits. There may also be aspects of your design that can “leak” microamps to milliamps of current that you don’t take into account.
Read the complete post at http://cmicrotek.com/wordpress_159256135/.