What is the maximum current on 3.3V pin?

Hey,

Does anybody know the maximum current i can safely draw from the 3.3V pin on the arduino mkr nb1500? And what would happen if i draw more than the maximum?

I did find it for the arduino mkr100, which is 50mA, but i am not sure if i can assume the same for the mkr nb1500 version https://components101.com/microcontrollers/arduino-mkr1000-wi-fi-board

Hope somebody can help me out.

Arduino pins are not designed to be used as power supplies. What are you planning to power from the 3.3V pin ?

Why not? The 3.3V pin is there to power sensors right?

I used the 3.3V port with a step-up converter to 20V to power this pressure sensor: Druktransmitter WIKA A-10 - 12963446 | Automation24

It works fine, but you suggest another way of powering it?

There is a big difference between powering a low current sensor and using the pin as a power supply for say a motor

Why not power the step up converter from whatever is powering the Arduino rather that the 3.3V pin ?

Ya i understand. But i am powering multiple low current sensors which adds up. Therefore my question about the maximum current on this 3.3V pin.

Why not power the step up converter from whatever is powering the Arduino rather that the 3.3V pin ?

Because i am only taking a measurement every 10s to extend battery life, and the easiest way to do that is by letting the arduino sleep, which also cuts of the 3.3V pin.

No, 3.3V is always on

No, 3.3V is always on

I measured the current consumption and during the arduino sleep mode the 3.3V is definitely not drawing any current from my sensors. I might not be wording this correctly as i am not an electrical engineer :stuck_out_tongue:

Matbe because your sensors are also sleeping?

Using this function: Arduino Low Power - LowPower.sleep() - Arduino Reference, which puts the MCU to sleep. I am not using any other code for the sensor sleep mode, because this seems to be enough to stop drawing current.

Can you post data sheet for all the sensors you are using.

Why would that matter? :wink:

Can you post data sheet for all the sensors you are using

Well i could, but i dont see how that helps my question to be honest, which was; what is the maximum current on the 3.3V pin

Why would that matter? :wink:

It would be nice if things wouldn't go up in fire :stuck_out_tongue:

It would be nice if things wouldn't go up in fire :stuck_out_tongue:

You can almost count on that. Here is the regulator data sheet:
https://www.diodes.com/assets/Datasheets/AP2112.pdf
It says the output Imax is 600mA, but the problem is, that spec assumes the best possible heat sink. Tiny board like that one, have basically the worst possible heat sink.

Looking back at the thread, you're being asked to calculate the sensor load and report back for opinions. How about it?

One thing you could do, to judge, is start adding sensors one by one, and feel the regulator chip with your hands, until it's only getting a little warmer than without any. Then stop adding sensors.

It already supplies the other stuff on the board, so it will begin a little warm.

Questions like this are why EE's get the big bucks.

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If you are not connected to a network and not transmitting, you can easily draw 250mA from the 3.3V
However, if you are connected and transmitting, I would not draw any more than 50mA.

So you need to know how much current all your sensors are drawing.

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Looking back at the thread, you're being asked to calculate the sensor load and report back for opinions. How about it?

Well i am trying to reason the other way around. How many of my sensors can i actually use, i could leave some out if needed. So that could be anywhere between 10-100mA.

But i think i will assume 50mA on this 3.3V pin and test it for a while in a safe environment.

Thanks! Did you found this in a datasheet? I couldn't find this number.

I won't be connected and transmitting data so the 250mA should be enough for my situation.

To use reason alone, you have to go through all the engineering hoops. Are you knowledgeable enough to do that?

The one I posted a link to. Reply #15.

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