https://store.arduino.cc/mega-2560-r3

Microcontroller: ATmega2560
https://www.microchip.com/wwwproducts/en/atmega2560

Power

Power in: From the USB connectors (5V) or the DC plug (7-12V)

5V reg: LD1117S50CTR, 2%, 1V dropout, 800mA output current rated

IO Pins

IO voltage: 5V

IO pin high voltage (for VCC = 5V): min 0.6VCC to max VCC + 0.5
So digital IO pins are compatible with 3.3V input signals.

IO Pin Current

Absolute max current per IO pin: 40mA

Absolute max current across all IO (and for uC itself): 200mA

Note that IO pins will drop voltage (move away from VCC or GND) as IO pin sing and source current increases.

Datasheet notes:

Although each I/O port can sink more than the test conditions (20mA at VCC = 5V, 10mA at VCC = 3V) under steady state conditions (non-transient), the following must be observed:
1.)The sum of all IOL, for ports J0-J7, A0-A7, G2 should not exceed 200mA.
2.)The sum of all IOL, for ports C0-C7, G0-G1, D0-D7, L0-L7 should not exceed 200mA.
3.)The sum of all IOL, for ports G3-G4, B0-B7, H0-B7 should not exceed 200mA.
4.)The sum of all IOL, for ports E0-E7, G5 should not exceed 100mA.
5.)The sum of all IOL, for ports F0-F7, K0-K7 should not exceed 100mA.
If IOL exceeds the test condition, VOL may exceed the related specification. Pins are not guaranteed to sink current greater than the listed test condition.

PWM

PWM is available on pins 2 – 13 and 44 – 46

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