Atmega328 Vcc pin

I received a comment from “N00B” on my Build an Arduino Clone post pointing out a mistake I made by connecting 5V power to the pin #6 instead of pin #7 of the Atmega328 micro-controller.

He was right and I changed the text of the article from pin #6 to pin #7 but, what puzzled me is that the circuit I made for this article was actually using pin #6 to power the micro-controller.

A basic Arduino clone
A basic Arduino clone - Vcc on pin#6 !!!

I still have this circuit all wired up in my lab. I validated that it works as well powered on pin #6 as on pin #7. How can that be? Anyone can explain that one to me?


  1. I’ve seen this before you can power a chip through an input, I’m pretty sure RFIDs use this (back powering) method to alleviate the need for an external power source.

    1. Eh, thank you for your comment … I guess you’re right, there is so much work involved in the development of these micro-controllers, this behavior must be “by design”. I should try to find more info about that …

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