Max current on 5v pin of an arduino one

Using Arduino Project Guidance
1

Hello,
i would like to know the value of max current available on 5v pin of an arduino one (i cannot find out the exact value). You can assume that i am using an external 12vdc power switch (capable of several amperes).

Thanks
Chech

2

Yes you look at the voltage reg on the card you have!!

Mark

3

I am tempted to say it's 1A. if you are trying to drive something with large power, you need a separate power supply.

4

0.5A is a better rule of thumb as that is "normally" what you can expect from the USB.

Mark

5

Regulator is only good for 800mA.
If powering from USB, only 500mA.

6

CrossRoads:
Regulator is only good for 800mA.

And that only for short periods and if you are powering from no more than 8V input. If you overheat it, it will simply switch off.

In general, do not expect to use the 5V output for anything more than a couple of hundred mA. So - not for motors (including steppers) or more than one small relay or an 8 by 8 matrix (driven by MAX7219) or more than one 1W LED (with a driver transistor buffering the Arduino pin).

7

Too many generalities there.
I have powered 4 MAX7219/8x8 matrices with 9V power supply.
Many telecom relays have relatively high coil resistances, and can be driven directly from an arduino pin.
Powering motors and high current LEDs, yeah, that's not good.

8

CrossRoads:
Too many generalities there.

Yeah?

What is the world coming to? :smiley:

CrossRoads:
I have powered 4 MAX7219/8x8 matrices with 9V power supply.

Well, I have three here in cascade plus a 1602 LCD with backpack and a little voltage display. It is sagging a bit to 4.85V from the USB port running a single chasing spot. If for some reason on initialisation or if I disturb the connections and all three matrices fully light, it really sags. I suspect if the same happened with the regulator on 9V, it might "time out" after thirty seconds or so.

CrossRoads:
Many telecom relays have relatively high coil resistances, and can be driven directly from an Arduino pin.

Oh I know - larger ones are generally more efficient. However they are not the sort that most people are going to be using with Arduino and I was thinking more in terms of big power contactors.