The NCP1117 provides a stable output voltage of 5V and a maximum current of 800mA for the ATmega328p.
Technically the maximum input voltage is 20V but because at 20V the voltage regulator is producing a lot of heat and would break after a short time period, it is recommended to supply an input voltage between 7V and 12V. The NCP1117ST50T3G is connected to the VIN pin and the DC power jack.