But, we need a mechanism to inform the MCU that there is a failure in the DC power system and then the MCU will save the critical data into its internal EEPROM. The posted circuit is not the only available design, there could be and there are many alternatives in the web some of which are not less complicated than the posted one.
Hey all,The result is possitive! as i think swich mode power say has a few capacitors on output of DC. When the main power is off, ardunio is going to work for 2-3 seconds and the eeprom can record!