June 10, 2010 -- Reducing power consumption has a major impact on every aspect of our lives. At a macro level, the benefits have been well-documented: lower electric bills for consumers, reduced load on utilities, and fewer batteries in landfills. In short, saving power is good for both the environment and the pocketbook. Due to the growing use of electronics worldwide, reducing power consumption must begin at the microchip level. Power-saving techniques that engineers have designed in at the chip level have a far-reaching impact, especially when involving microcontrollers that serve as the engines behind most of these electronic devices.

From a system-design perspective, identifying which microcontrollers are truly low-power requires designers to navigate through the myriad claims of various semiconductor vendors. Because of the varying and confusing metrics vendors use, this objective is a complicated task. This article briefly describes the main factors that you need to consider when analyzing competitive microcontroller alternatives. At a basic level, you can define microcontroller power consumption as the sum of active-mode power and standby, or sleep-mode, power. However, another important metric to keep in mind is the amount of time it takes for a microcontroller to move from a standby state to an active state. Because the microcontroller cannot do any useful processing until all of its digital and analog components are fully settled and operational, adding in this wasted power is important when calculating total power consumption. Thus, the device's total power consumption is the sum of its active-mode power, standby power, and wake-up power.

By Mike Salas. (Salas is microcontroller marketing director for Silicon Laboratories, Inc.)