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Topic: Vin and atmega8u2 (Read 503 times) previous topic - next topic

keda123

Hello.
Why when on Vin pin voltage is bigger than 6.5V the atmega8u2 MCU dont work?

Grumpy_Mike

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Why when on Vin pin voltage is bigger than 6.5V the atmega8u2 MCU dont work?

This doesn't make sense, what model of arduino are we talking about?

A voltage lower than 6.5V on the Vin will not allow the regulator to work correctly so the output will not be 5V.

keda123


Quote
Why when on Vin pin voltage is bigger than 6.5V the atmega8u2 MCU dont work?

This doesn't make sense, what model of arduino are we talking about?

A voltage lower than 6.5V on the Vin will not allow the regulator to work correctly so the output will not be 5V.

I use Arduino Uno.

Grumpy_Mike

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I use Arduino Uno.

Then this statement is not true:-
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when on Vin pin voltage is bigger than 6.5V the atmega8u2 MCU dont work?

What makes you think it is?

keda123


Quote
when on Vin pin voltage is bigger than 6.5V the atmega8u2 MCU dont work?

What makes you think it is?

Because when i get on Vin higher than 6.5V than voltage on USBVCC is less than 1V and serial wount work!!!

johnwasser


I use Arduino Uno.


Which model?  The R3 schematic shows that USBVCC is used for the +5V supply if half the VIN supply is less than 3.3V

Are you using a USB cable for serial I/O?  If so, why isn't the host system providing 5V to USBVCC through the USB cable?
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Grumpy_Mike

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Because when i get on Vin higher than 6.5V than voltage on USBVCC is less than 1V and serial wount work!

Sounds like your power switching circuit is broken.

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