What is the correct input voltage tolerance for the nano? I see 6-20V on the nano specs sheet, but I see 7-12V specified other places. Which is correct? To put it in context, will 13.6V fry my nano?
13.6V should be fine as long as you're not powering anything else through the on-board voltage regulator.
...The power (heat) dissipated is a combination of the voltage dropped across the regulator and the current through it. And the total temperature depends on that, the heatsink (just the PCB), and the ambient temperature so it's kind-of a difficult question.
The LM1117 voltage regulator is rated for 20V "absolute maximum".
And, you're right! ...The "tech specs" say 7-12V and the "documentation" says 6-12V.
from a different thread :
Quote from: Wawa Mon Feb 04 2019 01:09:05 GMT-0500 (Eastern Standard Time)
12volt is too much for a Nano. Official or clone. The datasheet says you can, but there are many threads here reporting blown Nanos with 12volt. At that voltage you can't draw much from any pin anyway, so why try. 6-9volt is much easier on the board, or power it directly with 5volt on the USB socket (phone charger).
There seems also a design fault in all Nanos. The regulator could blow up when external supply is connected while the Nano is powered from USB. Leo..
Cheddy: What is the correct input voltage tolerance for the Nano? I see 6-20V on the Nano specs sheet, but I see 7-12V specified other places. Which is correct? To put it in context, will 13.6V fry my Nano?
If you are asking this question, it is highly likely that you will wish to connect something else. In which case, the answer is regulated 5 V.
This is because the on-board regulator is essentially capable of powering only the microcontroller itself and no more than a couple of indicator LEDs. The on-board regulator might be able to power a few other things if it had a heatsink, but on the Arduinos, it does not.
A practical power supply for the Nano (or UNO, Pro Mini, Leonardo etc.) is a "phone charger" with a USB output connector for 5 V, generally up to a couple of Amps though you can not feed more than 500 mA through the USB connection.
If you want to power it from 12 V or a car system, you need a 5 V switchmode "buck" regulator to supply the 5 V.
Note that “real” lm1117 regulators are supposed to have internal protection against excessive power dissipation. Whether “clone” regulators have such protection, and whether a particular version of a nano has a real or clone regulator, is another question...
If you use an external regulator, it need not be a switching regulator...
12V through the Vin is OK for a quick test, if you don't have 5V available.
Use a car-type USB phone charger, those basically are 12V-5V buck converters and have basic overvoltage protection and so built in. Car power systems are notoriously noisy.