Continue to Site

Welcome to our site!

Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

  • Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Low voltage problem with Arduino MKR CAN shield

Diver300

Well-Known Member
Most Helpful Member
I've just found a problem with the Arduino MKR CAN shield, so I'm posting it here so that others can avoid the issue.

The problem is that the buck regulator goes unstable when the supply voltage is too low. Up to about 7 V input, the output will peak at near the input voltage. The output feeds the 5 V supply on the CANbus ICs, and it will often be used to feed an Arduino MKR. I've blown a couple of CAN transducers on the shields and a couple of the 3.3 V regulators on the Arduino MKRs, and I guess it's because the came from the CAN shields.

When I turn my bench power supply on with the button on the front that enables the output, the output voltage rises quite slowly, and while that is happening the buck power supply will oscillate a few times, exceeding 5 V most oscillations. I think that can damage other devices.

My fix has been to add 100 μF in parallel with the 5 V supply, very close to the output of the buck regulator. It doesn't stop the oscillations, but it helps drag the input voltage down during the brief period of the voltage peak. A better solution would be some low-voltage cut-off circuit.
 

Latest threads

New Articles From Microcontroller Tips

Back
Top