Selecting Low Power Micro-Controllers
When you are buying a custom power supply, the vendor will usually tell you the operating range of the device. However, selecting a low-powered microcontroller on the basis of an untested current consumption is a difficult job. In most cases, the embedded engineer who is selecting the MCU will look for details on the device, operating speed, peripherals, power characteristics and package information.
This approach is useful when you want to know the functionality of the device but not so much when you are trying to find out the MCU’s characteristics at low power consumption. To get a better understanding of how the MCU will perform at low power, you have to consider state retention, wake up sources, wake up time, current consumption and the peripherals that can operate at low power.
The MCU vendor will usually list the power requirements on the datasheet. The fact is, though the device may well achieve the specification given in the datasheet, the operating mode may not be useful or practical in the real world.
At the same time, some of the features of the MCU may be not be advertised like slow wake-up time, low range of operating voltage and no RAM retention. The datasheet may contain a number of low power specifications.
You can get around it by finding a common operating mode. The common operating mode will have two sections- functionality at low power and electrical specifications. Here too, a custom power supply can help you.