Powering Arduino via 5v Pin

Can i power the arduino from 5v Pin ?

i have 5v UBEC https://hobbyking.com/en_us/hobbykingtm-x3-ubec-3-5a-5v.html

i now only realized that Arduino uno Vin needs 7-9 volts. so i can't use this ubec to power it. (Arduino switching on when i connected ubec but it is unable to supply 5v at 5vPin)

(this is for future use, i dont want to do this now)
I also have afro esc https://hobbyking.com/en_us/afro-20a-multi-rotor-esc-simonk-firmware.html. can i used bec from esc to to power arduino Vin pin ?

Yes, you can apply a regulated 5V power source to the 5V pin to power the board.

pwillard:
Yes, you can apply a regulated 5V power source to the 5V pin to power the board.

The problem with this is that it has been reported to sometimes damage the board when doing this if USB is also connected to power (the power switching circuit accounts for power on Vin/barrel jack and USB at same time, but not 5v and USB at same time). For powering from 5v, I would hack up a USB cable and plug it into the USB port - thus physically preventing you from having external 5v and USB 5v connected at the same time.

DrAzzy:
The problem with this is that it has been reported to sometimes damage the board when doing this if USB is also connected to power (the power switching circuit accounts for power on Vin/barrel jack and USB at same time, but not 5v and USB at same time). For powering from 5v, I would hack up a USB cable and plug it into the USB port - thus physically preventing you from having external 5v and USB 5v connected at the same time.

Reported where? And are these reports of official Arduino boards, or an improperly executed clone? The Arduino, proper, appears to be correctly designed for this feature, so it seems strange, to me, that there would be such a problem with a proper Arduino, or even a clone that is properly made.

Let's stop perpetuating the worry. You'll be fine to do so.

DrAzzy:
For powering from 5v, I would hack up a USB cable and plug it into the USB port

I think i will go with this.

There have been a few reports here of 16u2 based boards blowing the 16u2 when powered by usb and the 5v pin. Unknown if they were clones or real.

Documentation for uno notes that supplying power via 5v or 3.3v pin may damage the board.

@ReverseEMF, if you look at the official Uno design you will see this IS a shortcoming of the real deal. If you use external 5V on it this WILL back feed into the USB port. The mosfet is only turned off if Vin in high enough. Your PC might be protected enough to be fine but it IS ugly / asking for trouble.

septillion:
@ReverseEMF, if you look at the official Uno design you will see this IS a shortcoming of the real deal. If you use external 5V on it this WILL back feed into the USB port. The mosfet is only turned off if Vin in high enough. Your PC might be protected enough to be fine but it IS ugly / asking for trouble.

Ah, yes...if BOTH a USB connection is made AND a 5V connection [from a separate supply] is made to the +5 pin, yes, that could be a problem. I thought the question was if you could exclusively power the board from a 5V supply connected to the Arduino's 5V pin. The latter is fine. The former could cause problems.

It is good practice in general not to power a device from multiple power sources. This is just another example.

An external 5V source to the 5V pin is fine but if you need to connect a powered USB cable then disconnect the external 5V first.

Steve