Power supply and board current limitations

Projects General Guidance
1

Hi there,

Most explanations regarding max current available at the 5V VCC pin recommend no more than a few hundred mA. I believe this recommendation is to prevent overheating the on-board voltage regulator. On one project I'm powering the Arduino by connecting a regulated 5V supply to one of its 5V pins (it's a Mega so has multiple 5V pins). I'm not using the on-board regulator. The power supply I'm using is capable of providing several Amps.

My question is, how much current could I draw from another 5V pin on the same board? Bear in mind that the current doesn't pass through the regulator or chip on its way from one 5V pin to another. I assume it's a direct track of copper on the Arduino board that connects all the 5V pins? So I assume the limiting factor is the capacity of the track on the circuit board and the capacity of the female header pins.

Normal current limits are based on capacity of the regulator, chip or power supply. Is it possible to damage the actual circuit board though when none of the above are limiting factors? If so any idea how much current that would take?

Thanks in advance.

BTW I know it's a weird question and that I could just draw the current directly from the power supply. It's for the sake of physical packaging and component layout that I'd like to draw it from another 5V pin.

2

Yes the limiting factor is the resistance of the traces on the PCB causing over heating and melting of the tracks.

My question is, how much current could I draw from another 5V pin on the same board

I have no idea and I don't think anyone has a definitive answer because it is a very wooly question. You can carry on drawing current until the tracks melt but you should be working well under that limit. How far under that limit is a moot point but if it were me I would not be drawing anything more than 1 to 2 Amps.

3

Thanks for your input Grumpy Mike. I was planning to pull just under 1A from the other pin. From what your saying it sounds like that wouldn't be ridiculous. I'll keep an eye on it. If I do find the limit and melt the trace I'll post the info back here in case anyone else is interested. Thanks again.