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Author Topic: AVcc low pass filter required?  (Read 1022 times)
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alabama
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Hi,
I just built my first breadboard Arduino (after I smoked my first Uno, 328 was still good). According to the tutorial I followed, to make use of the ADC, I need a low pass filter on pin 20 of the Atmega328 (AVcc)to get rid of power supply noise. Is this necessary? My o-scope shows only a few micro-volts noise even before plugged in to the two caps on the power input cicuit, I can't find anything after them.
 I want to use an analog accelerometer, not that critical as far as noise goes. If I will need it, any links to a schematic? Or just design my own for transient 60hz noise?
Thanks,
TomJ
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Very few arduino type boards or clones use a low pass filter to the Avcc pin, they just normally wire it to the Vcc pin with a .1ufd bypass cap to ground for some noise filtering. The AVR datasheet for a 328p chip does show a typical and recommended cap/inductor filter for the Avcc if you require the improved noise filtering method. It's up to you, most normally don't see the benefit in most applications.

Lefty
« Last Edit: March 04, 2012, 07:13:38 pm by retrolefty » Logged

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If you're not doing audio work, you can probably get by without it.
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Thanks fellas,
Nice of you to reply so fast.
TomJ
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