can any AVRs run full speed at 3.3v?

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Hi - I just discovered this little oddity of AVRs: as far as I can tell, they can only run at half speed at 3.3V. What the hell? I was planning on using an ATMEGA168 at 3.3V and 20Mhz, but now as far as I can tell that is not possible. Am I missing something? Is anybody else bothered by this?

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Hey,

It's not an oddity, a higher core voltage allows any processor to run faster. Even large Pentium chips this holds true for, as when overclocking them you increase the core voltage.

If you just need it for a one-off project, try running it at 20 MHz anyway. It might work.

-Colin

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c_oflynn wrote:
Hey,

It's not an oddity, a higher core voltage allows any processor to run faster. Even large Pentium chips this holds true for, as when overclocking them you increase the core voltage.

If you just need it for a one-off project, try running it at 20 MHz anyway. It might work.

-Colin


Well, I consider it an oddity because 5V is quickly becoming something of the past, but they're forcing us to continue using it. It's not like they lack the technology to make the parts fast enough at 3.3V - I mean I am using an AT91SAM7X256, running at 55Mhz at 3.3V.

Anybody know of any small dc dc converters that will step up 3.3 to 5? What a pain.

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Quote:
Well, I consider it an oddity because 5V is quickly becoming something of the past, but they're forcing us to continue using it.

Nobody is forcing you to run anything at 5V. You simply have to lower your requirements.
Quote:
It's not like they lack the technology to make the parts fast enough at 3.3V - I mean I am using an AT91SAM7X256, running at 55Mhz at 3.3V.

The SAM7 actually runs at 1.8 V, but the full speed is only attainable when running from RAM.
When running from Flash, the speed is about 30 MHz. This is only possible by using a 128-bit wide flash in connection with prefetch buffers and a 3-stage pipeline.
Quote:
Is anybody else bothered by this?

Not really. Different tools for different jobs.

/Jesper
http://www.yampp.com
The quick black AVR jumped over the lazy PIC.
What boots up, must come down.