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ADC input impedance

Posted: Sun Oct 01, 2017 6:34 pm
by kostyan5
Does anyone know... what is the input impedance of the ADC? Also, what are the resistor values of the attenuator pad?

Re: ADC input impedance

Posted: Mon Oct 23, 2017 4:56 pm
by ayavilevich
I am also interested to know this. Wasn't able to find this in the datasheet.

Re: ADC input impedance

Posted: Tue Jan 30, 2018 1:48 pm
by hgptamn
I would also like to know that; couldn't find it either!

Re: ADC input impedance

Posted: Tue Jan 30, 2018 4:02 pm
by BuddyCasino
Suddenly I want to know these things as well, even though I have absolutely no use for this information. I just love drama.

Re: ADC input impedance

Posted: Tue Feb 13, 2018 3:39 pm
by PiMaker
Though I don't have any hard values for input impedance since they aren't listed in the spec, it would seem dependent on which ADC you select. SAR ADC1 has a built-in LNA, so you should be able to configure it as a unity gain amplifier which as I'm sure you know will give you extremely low input impedance. The other ADCs don't have this feature so I presume the input impedance will be high like most microcontrollers. If you don't want jitter or slow sample issues, then you need to either use the integrated LNA or use an external op amp to feed the ADC.