AVR-Chat

On Sat, Jan 29, 2011 at 4:54 AM, ecros_technology
<Yahoo37849@ecrostech.com>wrote:

> --- In AVR-Chat@yahoogroups.com, farhan ahmad <a_decent22@...> wrote:
>
> > Could somebody comment what are the
> > pros and cons of using ATMEGA64L-8AU
> > with 16MHz oscillator crystal.
>
> Why even think of this?  Just use an ATmega64A-AU, which is rated for 16
> MHz operation from 2.7 to 5.5 volts.
>
> Graham.


Most ATMega chips are only rated for 16MHz+ speeds above 4.5V. If you run
below that you are limited to a lower maximum speed. Unfortunately that
tidbit is usually hidden fairly deep into the datasheet, so you really need
to dig to find it. For example, on the ATMega64A, if you check page 344 of
the datasheet you see that it is only rated to 10MHz at 3.3V:
http://www.atmel.com/dyn/resources/prod_documents/doc8160.pdf. That is not
to say that it would not work with a 16MHz crystal... It might work fine,
but you may get intermittent bugs or other problems. It is usually better to
play it safe and run at 5V and level shift to talk to the 3v3 components.


[Non-text portions of this message have been removed]