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 Posted: Jun 02, 2012 - 09:06 PM |
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Joined: Aug 12, 2011
Posts: 44
Location: Pakistan
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I have planned a low cost design.
My question is if Vcc is 5.2-5.7v DC
& 20MHz XTAL.
Does The AVR works fine? |
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Posted: Jun 02, 2012 - 09:15 PM |
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Joined: Nov 22, 2002
Posts: 12055
Location: Tangent, OR, USA
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The specs give operating characteristics to 5.5V. Absolute maximum is 6.0.
If you can absolutely guarantee that it won;t exceed 5.7, it is probably OK. Some things might be out of spec at the higher end. For example, current drain.
Jim |
_________________
Jim Wagner
Oregon Research Electronics, Consulting Div.
Tangent, OR, USA
"The only thing standing between us and victory is defeat" P.G.Wodhouse in Wooster & Jeeves series
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Posted: Jun 02, 2012 - 09:18 PM |
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Joined: May 24, 2004
Posts: 6002
Location: Tampere, Finland
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Speed and voltage specifications listed in the datasheet:
-Mega16 goes only up to 16 MHz at voltages 4.5V-5.5V
-Mega16L goes only up to 8 MHz at voltages 2.7V-5.5V
You are violating both speed and voltage specifications, so the design is not guaranteed to work. |
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Posted: Jun 02, 2012 - 09:20 PM |
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Joined: Dec 11, 2007
Posts: 6856
Location: Cleveland, OH
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Quote:
I have planned a low cost design.
My question is if Vcc is 5.2-5.7v DC
& 20MHz XTAL.
Does The AVR works fine?
No, for two reasons.
The ATMega16 is spec'd for a maximum of 16 MHz.
It MIGHT run at 20 MHz, but that is overclocking it, and it may not run at that clock frequency.
Secondly:
Although the Absolute Maximum operating voltage is 6.0 V, one doesn't generally run a Mega at > 5.5 V. (5.0 or 5.2 V would be the "normal" operating voltage).
JC
Cross post with both of the above... |
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Posted: Jun 02, 2012 - 09:43 PM |
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Joined: Nov 22, 2002
Posts: 12055
Location: Tangent, OR, USA
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I missed the 20MHz.
Might work. Might not. I would NOT count on it for a commercial application.
Also would not count on extended operation above 5.5V for a commercial application. OK for hobby.
Jim |
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Jim Wagner
Oregon Research Electronics, Consulting Div.
Tangent, OR, USA
"The only thing standing between us and victory is defeat" P.G.Wodhouse in Wooster & Jeeves series
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Posted: Jun 03, 2012 - 04:03 AM |
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Joined: Dec 01, 2003
Posts: 2502
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| Are you using a zener diode as a regulator? It can be difficult to attain exactly 5 volts. You can, however, use a TL431 as a zener substitute and get exactly 5 volts. |
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Tom Pappano
Tulsa, Oklahoma
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