Arduino Nano 33 IOT direct 3.3V power supply

Hello Everyone.

I was wondering if it would be possible to directly supply the Arduino Nano 33 IOT 3.3V on the 3.3V pin? Indeed, for my project I need to power the Arduino with 2 AA batteries, and I feel that it is kind of a waste to boost the 2 cells voltage to 5V (or similar) to to have it regulated down to 3.3V. Especially as I would like to save as much battery as I can for the project to last longer.
From what I saw on the schematic (see the attached file), the MPM3610 doesn't have any kind of protection (diode or similar). Would it be an issue?
Also I don't plan on uploading code while the Arduino is powered by the 2 cells ( I think it would be an issue in that case).

Thanks

@machiera You can only power the board via the USB port or VIN. Connecting a supply source to 3.3V pin (output pin) will damage your board.

Hello @machiera,

Does your project need to be on a Nano IoT? I ask because the latest Nano BLE's have a solder pad that you can cut to supply them with 3.3V batteries, see here for more details. Looks like cutting it disconnects the OUT of the MPM3610.

@dozie understood. I guess there are no easy work around.
@matt_lee_smith thank you very much for your suggestion. However I need to use Wi-Fi for this project. Nonetheless, I will keep that in mind if Bluetooth instead of Wi-Fi is required :slight_smile: .

Once again, thank you both very much for your feedback. It was highly appreciated and very helpful!

@machiera Welcome to the forum.

WiFi is very power hungry. Could you share some data about your application? e.g.,

  • How often do you intend to communicate/connect to a network?
  • How much data do you intend to send?
  • How long do you expect your application to work with one set of batteries?
  • Do you have any other power sinks?

@Klaus_K Sadly I can't share much information as it is meant to be used for a professional project. I know Wi-Fi is power hungry. However it doesn't require a 8000$ license like Bluetooth does. Otherwise I would have probably gave it a try.
Sorry I can't disclose much more information about the project :frowning: . Hope you understand.

BLE is a mass product technology, where $8000 is divided by large volumes. Using it for 100 units is unfortunately often prohibitively expensive.

I understand you cannot share any details about the product itself. Could you still share some general information about the active time and battery life you expect? e.g., connect once a day/hour ..., active for x minutes, lifetime y month/weeks ... ?

You are right it is not a mass production production, thus it is quite an expensive fee to pay

Without sharing too many details:

  • It should last at least 4 hours or more
  • It will be active and sharing data over Wi-Fi all that time.

I haven't used that Arduino in a while but from what I remember the data found here are pretty accurate: GitHub - ostaquet/Arduino-Nano-33-IoT-Ultimate-Guide: Arduino Nano 33 IoT - Ultimate guide

From my calculations it should be theoretically meet the requirements, but I wanted to check if I could make that more efficient. If that would I would be able to considerate AAA batteries (for size matters) and such :slight_smile: .

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I am powering the nano 33 iot throu the 3.3v pin with 3.3v without problem.

That is interesting. May I ask what kind of power supply regulator and battery are you using?
I am a bit curious as it goes against the recommendation from a tech support member (@dozie ). But maybe in the long run it is to follow @dozie 's advice. That is why I would like to ask for confirmation :slight_smile:

@machiera The pin outputs 3.3V through the on-board voltage regulator. If you supply 3.3V to this pin, the on-board voltage regulator is not protected from such. See the sch. at https://content.arduino.cc/assets/NANO33IoTV2.0_sch.pdf

This is the schematic.

For testing I use a breadboard with power supply 3.3v plugged in.

If I power it through the USB or Vin the measurements are not stable the internal power supply is oscillating.
The internal power supply can handle this.

To my regret there is a error in the drowing, the emitter of T3 should not be connected to the Battery this can be 4.2V witch is to high for the Nano 33 IOT but connected to the 3.3v line.

Thank you all very much for your feedback, I highly appreciate it!

@dozie I can see that. Is it similar to the raspberry pi where it is possible supply the board directly with 3.3V, but there is no protection unlike the recommended input pins/methods? So if there a voltage spike or such it will damage the board.

I am asking as based on @indyvh100 feedback, it seems possible to power the board directly through the 3.3V pin, as long as I don't use Vin and VUSB at the same time. Which makes sense as if both the MPM3610 and the other DC-DC converter I wish to use are not working at the same 3.3V, it might generate short-circuit / instabilities.