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Topic: USB and Vin at same time cause arduino burnout (Read 361 times) previous topic - next topic

sarunbalaji

Hi

I had designed my own arduino nano shield for a 2WD line follower robot. In my shield I am using 7805 to regulate Vin to 5v. Connected one diode to avoid reverse current flow before Vin. I am using 11.1v 1800mah Li-ion battery to power my bot. Whenever I try to check the sensor values in the serial monitor using USB my arduino getting very hot and failed I can't able to use the same arduino nano again.

I connected battery to Vin of arduino nano and the 5v from my external 7805 to arduino nano. I already burned 5 Nanos. When I disconnect battery to the Vin of arduino and power it with external 5V then it's working fine.

Why I am facing this problem??? This is happening only when both my BO motors starts running if I not using motors it's working fine

slipstick

I had designed my own arduino nano shield for a 2WD line follower robot.
But you haven't shown us your design or what components you are using or a circuit diagram of your project. I expect the problem is in there somewhere.

Steve

hammy

My guess , powering stuff from the Arduino...

sarunbalaji

sorry for the late reply please find attached schematic for my shield and correct me if i had done any mistakes

WattsThat

#4
Jun 06, 2019, 01:14 am Last Edit: Jun 06, 2019, 01:20 am by WattsThat Reason: Added question about version.
Issues with design: Very poor choice for D1 & 2, they should be Schottky type diodes for lower voltage drop. Worst possible choice to use a 7805 linear regulator with a battery, it's wasting more power as heat than it is doing work.

Two problems: Remove the connection between the cathodes of D1 and D2. Remove any connection to Vin and connect cathode of D2 to +5 of all components on the shield and the 5v connection point of the Nano.

Are those Nano clones or authentic Arduinos? There still may be an issue with the internal regulator of the Nano when powered by usb and no battery. Just need to know which version board.
Vacuum tube guy in a solid state world

sarunbalaji

Thank you for u response it's clone nano's. So u suggesting me to disconnect vin supply to Nanos just to power my Nanos only using +5V right?? Right now in one prototype I changed that and it's working fine. But my doubt is arduino having a switching circuit to change the power from Vin and USB right then why arduino getting burn??

I will also change the diodes to schottky diodes

Thank you

sarunbalaji

Which will be the best regulator for battery operated circuits rather than 7805

septillion

I connected battery to Vin of arduino nano and the 5v from my external 7805 to arduino nano.
Don't! OR power the Arduino with 5V onto the 5V-pin OR power it with >7V on Vin. NOT both. Your voltage regulator and the onboard regulator will try to fight to keep it at their slightly different understanding of 5V.

Extra note, on a Nano it's fine to power the Arduino via 5V and connect USB at the same time. On a Uno or Mega it's not!
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sarunbalaji

Don't! OR power the Arduino with 5V onto the 5V-pin OR power it with >7V on Vin. NOT both. Your voltage regulator and the onboard regulator will try to fight to keep it at their slightly different understanding of 5V.

Extra note, on a Nano it's fine to power the Arduino via 5V and connect USB at the same time. On a Uno or Mega it's not!
Thank you

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