Review on KOOKYE Nano V3.0 ATMEGA328P Module CH340C 5V 16M Mini USB Micro-Controller Board for Arduino (Nano5) - Enhanced Performance and Connectivity by Ryan Cornelius

As others have found out, the voltage regulator used in these "clones" Pro Micro does not handle 12V. Once the regulator is blown I would assume it's the 6V to 5V LDO regulators on the output. I can't say for sure without the data sheet. I say this because most regulators have a "maximum operating voltage" which is the normal operating range, and then they have an "ABSOLUTE maximum voltage" which is higher than the maximum operating voltage. Voltage at which the device can withstand Abs. Load for a short time until irreversible damage occurs. Once the regulator blew I'd say 12V was well over absolute maximum. The description says that the power supply should not be more than 9V. I'm assuming this is the absolute maximum, not the maximum work value. The specification for the original Pro Micro design is a Microchip branded LDO with a maximum operating voltage of 16VDC (so it can easily handle the 12V or even 14V supplied by most automotive alternators) and an absolute maximum Rated power from -20 to +20 volts (therefore reverse polarity protection is built in). These controls can be purchased from Mouser for about 70 cents each. So there are multiple ways to use them. First I would like to say that it worked fantastically when the device was unplugged from my USB port. I'm using Linux Mint as my operating system and I used the official Arduino software to write my sketch. I downloaded Sparkfun's Pro Micro library and was able to program the board like a Pro Micro. My sketches seemed to run without any problems. I booted my firmware, unplugged the laptop, and then plugged the Pro Micro into my 12V circuit. As soon as I turned the unit on, I saw smoke coming out of the VR. I quickly turned off the power. I thought something was wrong. I checked all my connections but couldn't find anything wrong so I plugged it back into my laptop (no 12v) and the lights on the unit came on then slowly faded until they went out. that was the last of them. I spent the next 3 hours going through the datasheets, my wiring, my code, everything I could think of to see how I might have wired something wrong. I even started removing the plastic plugs from the pins to inspect the hidden solder shorts but found nothing. I finally decided to check the reviews to see if anyone else had a similar issue and found several other stories that mirrored my own. I'm concerned and the reason I'm posting this detailed explanation is that some have made comments similar to "This is a 5V device, obviously it doesn't work on 12V". But these comments are completely off topic. They're rated to operate at up to 16V, which basically means it's safe to use a power supply rated up to 12V. The problem is using the wrong voltage regulator. All in all, I'm giving this 3 stars because it really worked. I tried estimating my cost of making some Pro Micro boards and buying the components myself and then building the boards myself, but ended up with a minimum price of $6-$7. Assuming the Atmega chips are real (i.e. not fake), the price of $19 for 3 of them is pretty steep. However, if you plan to use them, know your options: 1) Don't use them with a power supply rated for more than 5 volts. I would guess a 9V power supply would be fine for them. but possible 2) Replace controller. The Micrel Mic5225-5 is a real controller and can be purchased quite cheaply. Or another LDO SOT-23-5 with similar characteristics. 3) You can try a simple resistor divider, but I wouldn't recommend it. If I were to try this, I would start with a resistive divider consisting of two 100kΩ resistors with a 12V supply, which should result in a 6VDC to 6.5VDC voltage drop that the regulator could handle . I finally decided to return mine. It wasn't an easy decision because there is no other cheap option and they could probably work as I said above. Eventually my return window closed, I already had a fried unit and I had to decide if I was going to take the risk that nothing else would go wrong with them. I'll also say I was SUPER glad I didn't plug it into my laptop when I applied 12v. If that 12V fed back into my USB port I would be furious! Not sure if it could have happened or not but when everything starts smoking. Everything is possible. That solved me. I could risk losing the Pro Micros, but replacing the laptop would be a lot harder. Hope this helps someone else.