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From: Joerg <invalid@invalid.invalid>
Newsgroups: sci.electronics.design,comp.arch.embedded
Subject: Re: AREF bypass capacitance on ATMega2560?
Date: Wed, 21 Aug 2013 16:38:28 -0700
Organization: Consultant
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Vladimir Vassilevsky wrote:
> On 8/19/2013 3:14 PM, Joerg wrote:
> 
>> Folks,
>> What's the usual capacitance?
> 
> 0.1uF
> 
>> Any stability issues there?
> 
> Nothing special.
> 
>> I was planning
>> on using a 1uF X7R ceramic cap on the AREF pin of an ATMega2560, in
>> order to be able to use its internal bandgap reference.
> 
> Do not. Use Vcc as reference.
> Internal reference is inaccurate.
> 

Yeah, sure looks ghastly. I provided my own reference from another board
and filtered it with 0.1uF.


>> I saw people
>> using 0.1uF and 0.47uF. The datasheet is silent about stuff like that,
>> as usual.
> 
> It doesn't really matter.
> 

However, not everyone knows that because they don't say much about the
innards of the chip. It's my first ATMega case, or maybe the 2nd.

-- 
Regards, Joerg

http://www.analogconsultants.com/