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I have a voltage reference in the circuit and I thought I can feed that reference to AREF pin of ATMEGA as well:

The current at "1.024V" tag is around 200 uA, any current drawn by the AREF can affect the reference voltage to some degree.

  • Does the AREF pin draw any current? how much?

  • Can any noise on the AREF pin (or the MCU itself) affect the reference voltage?

  • Can I dump that 10 uH inductor (LC filter) which is recommended and used in most designs at AREF pin?

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  • \$\begingroup\$ What does the ATmega datasheet say? \$\endgroup\$ – Elliot Alderson Jul 1 at 16:20
  • \$\begingroup\$ @ElliotAlderson It seems that it's not mentioned in the datasheet! \$\endgroup\$ – ElectronSurf Jul 1 at 16:24
  • \$\begingroup\$ @ElliotAlderson that was the summary datasheet my bad sorry, this is the full datasheet, link. \$\endgroup\$ – ElectronSurf Jul 1 at 16:38
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Opened datasheet, Ctrl+F, aref, 38 clicks down there is a wonderful picture! As for two other questions:

  1. Yes, of course, external reference should be really as smooth as possible.

  2. Following from 2, depends on the precision you need (if you measure like 0.1 vs 0.4 V vs 0.8 V you probably don't care, but if you need 0.45 vs 0.5 precision, better keep the coil)

enter image description here

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  • \$\begingroup\$ P.S. I checked Atmega328p 3 clicks down, it's exactly the same! \$\endgroup\$ – Ilya Jul 1 at 16:35
  • \$\begingroup\$ Mine is Atmega8A but has the same graph, thanks. there's 2 questions left to answer though. \$\endgroup\$ – ElectronSurf Jul 1 at 16:36
  • \$\begingroup\$ added answers, sry, totally forgot about them when opened datasheet...:D \$\endgroup\$ – Ilya Jul 1 at 16:39

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