The challenge of identifying which MCUs are truly low power is rarely a simple task, requiring designers to navigate though the numerous (and often confusing) claims made by various semiconductor vendors. This paper helps cut through the clutter by using a simple formula to guide designers evaluating the power efficiency of different MCU alternatives: Total Power Consumed = Active Mode Power + Standby (sleep) Mode Power + Wake-up Power. Using this formula we’ll analyze each factor and how it relates to choosing a low power MCU for your embedded system.