What is the acceptable range for Vin voltage for the Ardrino Nano 33 IoT Board?
For the Ardrino nano the documentation clearly says "6-20V unregulated external power supply (pin 30)", but I don't see any such documentation for the Nano 33 IoT.
Thanks
On the Arduino Blog, there is an interview with the manager for the development of the Arduino Nano 33 IoT:
That interview contains this helpful bit of information:
On-board DC-DC power supply enables the board to be powered up to 21V maintaining high efficiency and offering a lot of current to external devices without overheating. This is a big improvement over other products on the market that have LDO and heat up quite a bit when powered at high voltages.
Unfortunately, that only tells us the maximum of the voltage input range, and doesn't say anything about the minimum. We do know that the board can be powered via 5 V from the USB cable, so certainly the minimum is 5 V or less.
Of course, this information should be documented right there on the product page. Since it's a new product, the documentation for the Nano 33 IoT is still in progress and I'm sure this information will be added eventually. If you want to speed that along, you can submit an issue report about the missing information here:
I could not find an official specification.
The used MPM3610 (https://www.monolithicpower.com/pub/media/document/MPM3610_r1.01.pdf) states 4.5v to 21v
Note when underpowering you might get strange behaviour. I am using an LM2596S step-down module with a 24v 6.25a power supply as input. Tuning the output to 5v without the Arduino connected, resulted in a dim power led a few seconds after power up and a non-working NINA Wifi /BLE module. Also when also using the USB connection, 2 serial ports with the same name showed up all the time in the Arduino IDE and did they didn't work. I guess this is due to voltage drops under load.
So it might be wise to aim a little higher than 5v when using a less stable power supply.
Wanting to know the 'best' voltage to use, I've found that seems to be designed for 12v (see page 16 of the MPM3610 specification) and the resistors specified in the schematics. (https://content.arduino.cc/assets/NANO33IoTV2.0_sch.pdf)
It's very strange that it wouldn't work at 5 V, since that's the voltage that is provided by the USB connection. It might have been that your power supply wasn't capable of providing enough current. That could cause the microcontroller to reset, resulting int the duplicate port problem you saw.
This deficiency in the documentation has been reported to the appropriate people at Arduino and they are now working to resolve the issue.
Not sure, on paper it should be ok.
But mind I am using a very cheap step-down module: https://nl.aliexpress.com/item/32960454047.html
that might be the cause of the issue.
I saw the voltage dropped while connected to the Arduino.
Recalibrating the supply to 5v with the Arduino connected solved the issue.
Because the output is variable I've set it to 12v to be on the safe side.
I was reading this thread trying to find a number since there is a lack of documentation until I realized I hadn't checked the box of the one I received.
Input Voltages: 5V (Input-USB), 4.5 - 21V (Input-VIN), 3.3V (Operating).
I've attached a picture of the back of the box.
Hope this helps.
RyanD808's picture:
Good to know! I don't own one of these boards yet so I had never seen the box. It's nice Arduino utilized that space to provide some useful information.
So that would mean i could just connect a 9V battery and the nano will work?
mihai93:
So that would mean i could just connect a 9V battery and the nano will work?
Yes, but if by "9V battery" you mean the batteries commonly used in smoke detectors, it's not the best choice. The reason is that these batteries can't supply much current. This means the battery won't be able to power your Arduino board very long and it also won't be able to power any additional components that draw a lot of current like a motor at all. A better choice would be a 4x AA or AAA battery pack or one of those USB power supplies.
My experience with the Nano 33 IoT is that providing 5V on the Vin pin is not enough when working with the wifi (even if the power is provided by a DC power supply which gives up to 5A).
It is strange because the USB power is 5V and it's working fine when connected on the PC...
That is odd. The only difference I can see from the schematic between powering from the USB jack at 5 V and powering via the Vin pin at 5 V is that the Vusb goes through a Schottky diode before being connected to Vin. So the voltage drop from the diode will actually make the 5 V from Vusb less than the 5 V you would get from the Vin pin by the time it reaches the MPM3610 step down voltage converter.
Is it any safer to use a 12V input to the vin in the 33 iot Nano compared to a standard Nano? I read several threads with people claiming their Nano blew up feeding it 12V.
With ANY arduino it is always better to err on the side of caution.
I often run boards UNDER the 12 volts (8-10) so that the regulation side of the boards have less work to do and don't just become a wasteful heat source.
Not lost a single board to overvoltage. Other mistakes on my own part yes but not overvoltage.
Bob.
Thanks bob, I'll be a little cautious and use a switching regular to step 12V -> 9V to the Arduino vin
I think what I will do, for portability, is just use 2 x 18650 batteries in series.
I have a nano 33 IoT that uses DHT22 and BMP280. It receives and sends UDP over WiFi. It runs like a clock on any voltage down to and including 4.5 volts. At 4.5 volts the 33 uses about 40 ma base and in the mid 50s ma upon transmit.
At 3.0 volts, the nano 33 power light doesn't come on. The min voltage for the 33 is somewhere between 3.3 and 4.5 volts. I would like to try a 3.7 volt (lithium) battery next. Why anyone wants to use 10-15-20 volts for this seems strange.
As already mentioned above, 4.5 V is the minimum input voltage, as specified in the MPM3610 datasheet. Maybe you can get it to work with less, but you have no guarantee of reliability at lower voltages.
sainohio:
Why anyone wants to use 10-15-20 volts for this seems strange.
If that's the voltage you have available, then you're going to want to use it.
Well, just as an anecdotal note, I am currently running the 33, WiFi and all, on a 3.7 lithium battery (fully charged showing 3.96 volts), and it has run perfectly so far, through varied environmental conditions, and distance testing.
As far as the supply voltage goes...
This is suppose to be a low power device. Are you saying that it will draw no more current at 20 volts than it will at 5 volts?
sainohio:
This is suppose to be a low power device.
It's capable of low power operation, but that isn't necessarily going to be the primary consideration in all use cases.
sainohio:
Are you saying that it will draw no more current at 20 volts than it will at 5 volts?
There's a cool chart on the first page of the MPM3610 datasheet:
So you can see the answer is "it depends". There is a range of conditions where it will actually be more efficient with a 19 V supply (<80 mA load current) or a 12 V supply (<65 mA) than a 5 V supply. A low power device will likely be in that load current range almost all the time. You may be used to a different situation with the traditional Arduino boards that use a linear voltage regulator.
Sorry, I assumed lower voltage would mean lower current draw. Actually the opposite it true.
At 4.5 volts (battery) the baseline current draw is 42 mA
At 9.0 volts (battery) the baseline current draw is 30 mA
At 12 volts (wallwart, true voltage 13.7 volts) it is 18 mA
So it appears that what I need is a high capacity 20 volt battery about the size of the nano. 
The 3 X AAA or 3.7 li-ion idea just won't work unless I can make big magic on the power saving stuff.
