Arduino mega R3 Mega (core to ATmega2560) is a development board (used with16MHz crystal oscillator ) of microcontroller. There are 54 I/O (input/output ) digital interfaces (of which 14 are PWM outputs), 16 analo g inputs and 4 UART (hardwareserial ports). With its bootloader, program can be downloaded directly with USB and you don’t need to use other external programmer. It can be driven directly by USB, or AC-to-DC adapter and battery.
Design of Power Supply :
There are two choices (direct power supply trough USB or external power supply) for the power supply system of Arduino Mega, and they can be Automatic switched. External power supply can be AC-to-DC adapter or battery. Voltage input of this control board is 6V~12V, but if the supplied voltage is greater than 12V, the voltage stabilizing device will be likely to be overheated and damaging Arduino MEGA. So we suggest the power supply should be 6.5~12V in operation and recommended supply is 7.5 or 9V.
Input Voltage (recommended):7-12V
Input Voltage (limits):6-20V
Digital I/O Pins:54 (of which 15 provide PWM output)
Analo g Input Pins:16
DC Current per I/O Pin:40 mA
DC Current for 3.3V Pin:50 mA
Flash Memory:256 KB of which 8 KB used by bootloader
Clock Speed:16 MHz