The power consumption for the device can be estimated by determining all the different currents involved and adding them.  The following is list of different components that should be considered for supply current:

 1) Digital supply current at the operating frequency and supply voltage.  The datasheet for the microcontroller provides guidance for this estimate in the Global DC Electrical Characteristics section.

 2) Current consumed by any used analog peripherals on the device, including the VDD monitor, oscillator, ADCs DACs, etc.  The required supply current for each of these components is available in the appropriate section of the datasheet.

 3) Any current requirements of the digital I/O pins.  For example, if you are driving a logic high out of a port pin to drive an LED, this will increase the supply current going to the microcontroller by the amount of current required to drive the LED.