# Current vs Voltage, Power Supply question

Hey all!

What is the best way to calculate the total current that the Arduino MEGA 2560 needs in order to fulfill everything we need to do (in aspects of the pins we'll be using)?

To be more specific, could is be calculated based on the number of pins we'll be using?

Also, the 3.3V and 5V pins will be used as well. How should the input voltage be calculated in order to ensure that the board doesn't get too hot and powers off due to it?

Thanks!

turftec:
Hey all!

What is the best way to calculate the total current that the Arduino MEGA 2560 needs in order to fulfill everything we need to do (in aspects of the pins we'll be using)?

To be more specific, could is be calculated based on the number of pins we'll be using?

Also, the 3.3V and 5V pins will be used as well. How should the input voltage be calculated in order to ensure that the board doesn't get too hot and powers off due to it?

Thanks!

Well it's not the number of output pins you plan on using to is important, but rather the load resistance you wire to each output pin used. Once you know the load resistance on a output pin you can calculate the current demand on that pin, repeat for all the used output pins. Also the load resistance you put on the 5V and 3.3V pins will determine the amount of current that will be drawn from those pins. Once you know all the load current values just sum them up and add about 80ma for the basic board's 'overhead' current requirements and you should then be in a position to calculate the power dissipation of the on-boards voltage regulators assuming you also know the input voltage value you plan on supplying to the board. Note that the Arduino folks rate the maximum current output for the 3.3v pin at 50ma.

Lefty