Hi, i didn't use my Arduino for a while and i tried to power it with 3.3V with a Li-Ion 3V battery. Turns out that my 3.3V pin is broken! Is there a fix for it or did i just burn 500 Turkish Liras (25$)?
Addition: The Uno still works, just not the 3.3V pin.....
You cannot power a Uno R3 using its 3.3V pin. It is strictly an output pin that outputs 3.3V when the board is correctly powered from USB or an external power source
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Oh sheet! I must've broke the 3.3V pin!
It shouldn't break because it didn't power on though?
Maybe not. Power it from USB and measure the voltage on the 3.3V pin
Ok, let me get my multimeter
It shows ~3.25 Volts, that oughta be normal, right?
That sounds OK
OK, appreciate the help!
Greetings from Türkiye (Turkey)!
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To say that the Arduino cannot be powered via the 3v3 pin does not seem to be correct.
According to https://docs.arduino.cc/learn/electronics/power-pins#3v35v-pin, "Powering via the 3V3/5V pin" is an option. Later, that same link says, "It is safe, but not recommended, to apply a voltage to the 3V3 or 5V pins that are not higher than the input voltage of the voltage regulators. Still later in that document it is said, "It can be done safely if the applied voltage to the 3V3 or 5V pins is not higher than the input voltage of the voltage regulators."
After a lot of searching and forum reading, I was unable to find anything explicit about "the input voltage of the voltage regulator" of the Arduino Uno R3.
What is the input voltage of the voltage regulator of the Arduino Uno R3? What is the maximum voltage that can be input to the 3.3v pin?
Many thanks for your insights.
That is certainly what it says, but I don't see how it could work because, as far as I know the Uno has no way of converting the 3.3V input into the 5V that is needed for the output from the GPIO pins
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The 3.3volt pin on an Uno R3 is a 3.3volt/150mA (absolute max) output, not an input.
You probably missed "(depending on the board)".
The 3.3volt VCC pin on 3.3volt-logic board could be an input.
The Uno R3 schematic diagram is on this website. Understanding it explains it all.
The Uno R3 can be powered several ways
- USB (5volt), with a computer/laptop or 5volt cellphone charger connected to the USB socket.
- DC socket, 7-12volt according the spec sheet.
- V-in pin, which bypasses a reverse protection diode with a 0.7volt drop, so in theory the range would then be 6.3 to 11.3volt.
- 5volt pin (with 5volt).
Dangers.
DC socket and V-in should be listed as >7.3volt and > 6.6volt respectively,
because the USB backflow protection doesn't work below these voltages.
The USB backflow protection (back-powering the laptop's USB port) doesn't work at all when you power the Uno on the 5volt pin, so unplug USB when you do this.
Beware that backflow protection also doesn't work (at all) on some clone Uno R3 boards, like the Elogoo R3, because of a production fault (wrong LM358 chip). Other clones might have the same issue.
Powering the Uno R3 via DC socket or V-in uses the 5volt regulator, which gets hot from voltage difference * current draw. Higher input voltage means lower current capability. With 12volt on V-in, that drops to 100mA total from all pins.
Leo..
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