Which of these specs is most important? Take a look at practical example, an ultra-low power system such as a wireless sensor network. In these systems, the CPU and related peripherals are only active roughly half a percent of the time and asleep during the rest of the time. During the active mode, measurements are usually acquired and data is often transferred or analyzed. To put it into numbers, this duty cycle corresponds to a 50 millisecond burst of activity every 10 seconds.