At some point, the application needs to wake-up and execute a function. Wake-up from sleep is triggered by a reset or interrupts, with the most common being an RTC (Real Time Clock) interrupt. The AVR’s RTC mode is called Power Save (PS) mode. With a supply voltage of 1.8 volts, the AVR picoPower technology achieves a very low PS current consumption of 650nA with the 32kHz oscillator running, and a sleeping brown out detector (BOD).