user28475: While researching minimum-voltage requirements of Uno, I came across what appear to be two datasheets for the ATmega328P:
http://ww1.microchip.com/downloads/en/DeviceDoc/Atmel-7810-Automotive-Microcontrollers-ATmega328P_Datasheet.pdf
http://ww1.microchip.com/downloads/en/DeviceDoc/ATmega48A-PA-88A-PA-168A-PA-328-P-DS-DS40002061A.pdf
Specifically, the power requirements (and processor speed for each power level) differ. How could I know which datasheet applies to the chip I'm using? I'm actually using an Arduino clone:


user37622: You have ATmega328P-AU. Classic Uno with DIP socket has ATmega328P-PU. Arduino Uno SMD has Atmega328P-MU.
The automotive versions ATmega328P-15AZ and ATmega328P-15MZ have separate datasheet starting in Revision History with

Creation of the automotive version starting from industrial version
  based on the ATmega48P/88P/168P/328P datasheet 8025F-AVR-08/08.
  Temperature and voltage ranges reflecting automotive requirements.


28475: <p>While researching minimum-voltage requirements of Uno, I came across what appear to be two datasheets for the ATmega328P:</p>

<p><a href="http://ww1.microchip.com/downloads/en/DeviceDoc/Atmel-7810-Automotive-Microcontrollers-ATmega328P_Datasheet.pdf" rel="nofollow noreferrer">http://ww1.microchip.com/downloads/en/DeviceDoc/Atmel-7810-Automotive-Microcontrollers-ATmega328P_Datasheet.pdf</a></p>

<p><a href="http://ww1.microchip.com/downloads/en/DeviceDoc/ATmega48A-PA-88A-PA-168A-PA-328-P-DS-DS40002061A.pdf" rel="nofollow noreferrer">http://ww1.microchip.com/downloads/en/DeviceDoc/ATmega48A-PA-88A-PA-168A-PA-328-P-DS-DS40002061A.pdf</a></p>

<p>Specifically, the power requirements (and processor speed for each power level) differ. How could I know which datasheet applies to the chip I'm using? I'm actually using an Arduino clone:</p>

<p><a href="https://i.stack.imgur.com/1lNvQ.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/1lNvQ.png" alt="enter image description here"></a></p>
 37622: <p>You have ATmega328P-AU. Classic Uno with DIP socket has ATmega328P-PU. Arduino Uno SMD has Atmega328P-MU.</p>

<p>The automotive versions ATmega328P-15AZ and ATmega328P-15MZ have separate datasheet starting in Revision History with</p>

<blockquote>
  <p>Creation of the automotive version starting from industrial version
  based on the ATmega48P/88P/168P/328P datasheet 8025F-AVR-08/08.
  Temperature and voltage ranges reflecting automotive requirements.</p>
</blockquote>
