How is the power via USB filtered in an Arduino Nano

[SolarTrap]

Hello all,

I have an issue with the 5V input to the Arduino Nano. I noticed that when I power (using a power bank) my Nano via the USB port I get a clean ADC reading from my microphone but using the same power via the Vin pin I am getting noise. This makes me think there is a filter in the path. I have attached the schematics, can someone identify what that filter is?

Thanks,
Markus

 

[IRstuff]

Your schematics are not readable unless you tell us what the secret program is. Even then, good luck with finding people that own that program

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

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[3DDave]

If it is a genuine Arduino Nano there is a schematic and BOM at

https://www.arduino.cc/en/uploads/Main/ArduinoNanoManual23.pdf

It just looks like a couple of caps on the USB input, C8 and C9.

OTOH, there are a bunch of caps on the 5V rail, C2, C3, and C10.

 

[IRstuff]

In that schematic, the USB adds C8 and C9 to C2, C3, and C10 via the Schottky diode D1, so ~50% more capacitance, but you do lose 0.1-0.2V through that diode.

But the noise could come from elsewhere, since a power bank is essentially pure DC. It may be that the FT232RL might be generating noise that's suppressed when it's connected to your power bank.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

https://www.youtube.com/watch?v=BKorP55Aqvg

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[itsmoked]

That power bank could easily have a switcher in it.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[MacGyverS2000]

How about hooking it to a scope and seeing what this so-called noise looks like... that will probably give a gigantic clue as to where it is coming from.

Dan - Owner

http://www.Hi-TecDesigns.com