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Topic: 10uH inductor for AVCC (Read 1 time) previous topic - next topic

pico

Nov 23, 2012, 07:08 pm Last Edit: Nov 24, 2012, 04:10 pm by pico Reason: 1
I was going to experiment with putting a 10uH inductor in series with the AVCC supply to an atmega328, as discussed in the "AtmelAVR042 AVR Design Considerations" sheet.

I've purchased a few 10uH inductors in packages similar to 1/4 resistors, rather than the more traditional style of inductor packages... should these be equally suitable for this application?
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dhenry

It works. Just watch out that those inductors have  minimal inductance at high frequencies and saturate easily (not a problem for your application).

Osgeld

yea they should be perfectly fine, and it does make a little difference, my first arduino board/kit had it in a smd package and so I included it, when that board crapped out (mechanical issues) I made another without ... for the things I have used analog in for it didnt make much of a difference, but then again I dont really have a huge need for analog in.
http://arduino.cc/forum/index.php?action=unread;boards=2,3,4,5,67,6,7,8,9,10,11,66,12,13,15,14,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,86,87,89,1;ALL

MarkT

My experience with analogRead monitoring battery voltage is that a battery powered circuit without any heavy output loads seems to perform pretty well (< 1 lsb fluctuation) with no filtering on AVcc, but when powered from a DC->DC converter there is noticeable noise (several LSBs), and an LC on AVcc is probably the way to go.  In other words the inductor will make a difference if there's already a source of noise, otherwise its probably not needed.  switching output loads will also generate noise, its not just the source of supply voltage than matters.
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Where did you get the value of 100µH? Page 260 of the ATmega328 datasheet shows a schematic with a 10µH inductor. That's what I used on one of my boards with a switch mode power supply powering the ATmega.
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dhenry

The actual value of the inductance doesn't matter: what really matters here is actually its resistance.

pico

#6
Nov 24, 2012, 04:09 pm Last Edit: Nov 24, 2012, 04:11 pm by pico Reason: 1

Where did you get the value of 100µH? Page 260 of the ATmega328 datasheet shows a schematic with a 10µH inductor. That's what I used on one of my boards with a switch mode power supply powering the ATmega.


You are correct. The inductors are 10uH. (I can't read my own handwriting!)

I've gone through and corrected the value in these posts wherever I can correct.
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