QT PY RP2040 +5V input

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gjk_baker
 
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QT PY RP2040 +5V input

Post by gjk_baker »

Currently when using a Feather, I can simultaneously apply power via the USB and BAT

I am now designing with a QT PY RP2040, and want to power simultaneously with USB and an external source.
Per the documentation, https://learn.adafruit.com/adafruit-qt-py-2040/pinouts, I have added the diode on the +5V line.
The external source is at 3.1 after the diode.

It works for a few minutes and then the RP2040 is fried. I now have a pile of parts on my desk.

What am I missing??

thx

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dastels
 
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Re: QT PY RP2040 +5V input

Post by dastels »

3.1v will be too low at that point. That goes into the 3.3v regulator and should be at least in LiPo voltage range (3.7)... enough for the regulator to work with. I'm not sure why that would fry boards, but I can see how it just wouldn't work.

Dave

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gjk_baker
 
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Re: QT PY RP2040 +5V input

Post by gjk_baker »

Dave

Just to confirm,
It is okay to supply the QT PY via USB and an external supply simultaneously and I should look elsewhere for the problem.

GB

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dastels
 
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Re: QT PY RP2040 +5V input

Post by dastels »

Basically, if it's another 5v supply. Or at least high enough (after the diode) to run the regulator. say >= 3.7v. Frying the board is probably somethign else as I expect too low of an input voltage wouldn't do much of anything.

Dave

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gjk_baker
 
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Re: QT PY RP2040 +5V input

Post by gjk_baker »

Thanks

Operator error, found my problem

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