access Nano USB port power


I have a Nano v3 and would like to drive 10 neo pixel LEDs which are 5 volts.
is there a pin on the Nano that access the USB power pin directly?

I heard you can not drive too much amps through the Nano so thought what if I get it from the USB port with USB charger connected.

goal is to power the project with phone charger.


As the Nano doesn't have a USB over-current protection (as most other Arduinos have) this might work.

As the Nano doesn't have a USB over-current protection (as most other Arduinos have) this might work.

Ok, so do I use the VIN pin or the 5v pin?

The VIN pin probably doesn't have any voltage if the Nano gets powered by USB. Use the 5V pin.

The Vin pin DOES have voltage on it, but it's flowing through a protection diode in the regulator as far as I can tell; someone burned out the voltage regulator on their nano earlier this week drawing power off the Vin pin while connected to USB.

Use the 5v pin. You may have problems with 10 neopixels. At full white, they're like 60mA each, plus 50 or so for the nano itself, you're looking at 650 mA. I think the schottky diode in series with the USB power is rated for at least 1A, I thought 1.5 or 2 - so you're good there - but the USB standard says a port is not supposed to supply more than 500mA without the device asking for it (strictly speaking, devices are supposed to ask if they need more than 100mA - but I've never seen a host that enforced that); the rigor with which this is implemented varies between devices; some will refuse to supply over 500mA, but most will let you pull more (and basically any wall-charger will).

The 5volt pin can be used to power things, but it's only 4.6volt on a Nano because of a USB backflow protection diode (with ~0.4volt drop) between USB power and the 5volt pin.
Direct USB supply is not available on the Nano (as on most other Arduinos).
That diode has an absolute max rating of 500mA, and so has a USB2 port.
With 10 Neopixels and the Nano itself (~600mA) you are in the danger zone.
Never draw current from V-in if on USB power.
Current will flow backwards through the 5volt regulator, and will almost certainly fry it.