@mfalkvidd
Thank you for your fast answer

Hi team,
By curiosity running the Atmega328p at 8mhz down to 1.8v isn’t out of spec ?
Does it work reliable ?
Should we div8 clock speed than mesure vcc and set prescaler accordingly ?
Just by curiosity for further project I see a lot of info to not go above 4Mhz at 1.8mhz as the data sheet and other that it’s working stable even a 8mhz

Thanks all !