As we know that, everything is marketed as Low Power or Ultra low power. I understood that we can classify the controllers based on their application and clock cycle for the above mentioned sections. But what makes me little confused is what contributes to these facts of Low Power and Ultra Low Power consumption because the application basically demands the average power consumption. Then how MCU can be classified into these categories. Speaking from architectural point, are there any significant differences? I know it is a very basic question and can get points from Internet, but I didn't find sufficient explanation towards a customers point of view. It would be helpful if experts can give me some ideas about difference between Low Power & Ultra Low Power designs.
closed as primarily opinion-based by pipe, Voltage Spike, Dave Tweed♦ Sep 30 '17 at 14:30
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The power consumed by an application/device can be divided in aspects:
a) the power needed to do the required amount of computation
b) the power required by the chip in its lowest power mode (sleep, deep sleep, hibernation, etc.)
c) the power required by the chip while doing the barest minimum of activities
Depending on the application, one or more of these aspects will dominate the overall power consumption. Low power chips generally have a very low power mode, reducing the power for aspect b), and ways to have the hardware take care of c) (responding to keypress, timeout, A/D conversion completed, etc.) without involving the CPU (thus reducing power).
Low Power or Ultra Low Power are just marketing terms without any agreed-upon kwantitative meaning. A manufacturer has to come up with a new term for the chips that do better than its previous range of Low Power chips... But an engineer doesn't care about the name. The datasheet (and often info beyond that) is what realy counts.
For a given clock cycle and a given instruction execution, the underlying hardware makes a lot of difference in the amount of power consumed by the uC. So also does the state of the uC (Active / Sleep / Low Power state, etc).
Based on those parameters, manufacturers classify their products into buckets called low power and ultra low power. There is no specific standard.
As an application developer, if you have a requirement where power consumption is a huge criteria, then you can start selection in the ultra-low power series of uC's. Again, your application power requirement can even be met by a "normal" uC. So those classifications only serve as a starting point for your search.