Atmega644pa High frequency for 3.3v

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#1
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Recently I decided make my project portable and using li-po batteries which is 3.7v then decided to run my circuit at 3.3v,because of my circuit has spi sram, i need the highest frequency i can reach with Atmega644pa. i was considering running @8Mhz but after some research i came across A-Star 328PB Micro - 3.3V, 12MHz 

 

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i have looked at the datasheet it seems 12Mhz may be ok,does anyone have experience with 12Mhz 3.3v avr ,is it ok or if not what kind of problems are waiting for me.

(here is the atmega644 speed grades)

 

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

 

Thank you in advace.

 

emre

Last Edited: Wed. Apr 8, 2020 - 07:34 AM
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You are fine running at 12 MHz @ 3.3V.

 

The chip spec, from the graph, shows that the chip will run at 12.88 MHz at 3.3 V, in spec.

 

(Calculate the slope, m, of the graph, then the b intercept, and then the speed for V = 3.3).

 

Good luck with your project!

 

JC

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The PB version of any new chip is not the same as what you show above! The clock curve seems the same but I only have the 2018 version.

 

 

John Samperi

Ampertronics Pty. Ltd.

www.ampertronics.com.au

* Electronic Design * Custom Products * Contract Assembly

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From the image in Post#1:

This version features a 12 MHz resonator and a 3.3 V regulator that can be powered from 3.8 V to 15 V supplies.

 Your 3.7V battery is out of spec.  Also, the battery voltage will fall as it is used - the near empty voltage will be less than 3.7V.

 

 

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The point is an avr can run or not 12Mhz in 3.3v operating voltage. Supplying it is another task for me

emre

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Then, what is the question?

 

Jim

Jim Wagner Oregon Research Electronics, Consulting Div. Tangent, OR, USA http://www.orelectronics.net

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kayanemre wrote:
does anyone have experience with 12Mhz 3.3v avr ,is it ok or if not what kind of problems are waiting for me.

 

emre

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Starting in post #2, you have been told in various ways that...

 

You are fine running at 12 MHz @ 3.3V.

In addition you have been warned that using a Li-Po battery will decrease in voltage and limit that operating frequency to which you have said...

 

3.3v operating voltage. Supplying it is another task for me

So... the only problem that I see at the moment is you not understanding what you have already been told. Am I wrong?

 

Moderator

 

Ross McKenzie ValuSoft Melbourne Australia

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no I already understood in first comment it is not so complicated,I just want to stress what is the question.

 

emre

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The question has been asked and answered. End of the story.

 

Locked.

 

Ross McKenzie ValuSoft Melbourne Australia

Topic locked