High Power Motor Drivers and Electrical Noise


I want to connect two Motor Drivers 18v15 with my arduino. I am concerned that electrical noise from motors may pass to the arduino and the devices connected to it (Sonars, IR distance sensors, WiFi). The motors have a 6Kg-cm running torque and have a 2A stall and are kept 5 cm away from the arduino.

Should I be concerned about any noise transferring through these motor drivers? Do you recommend that I use opto couplers ?



There are all kinds of ways for noise to get in your system once you’re using motors, and I think going to optoisolators is something you might consider after doing all kinds of other things. A major thing is your power source; are you using a separate one just for the motors? (It doesn’t make much sense to isolate your signals when your power is shared.) Even things like the routing of your wires will probably have more effect than whether or not you have the optoisolators.

Separately, those motor drivers are quite a bit of overkill for the motors you’re describing. Have you considered something like our dual MC33926 carrier? It’s half the price, smaller, and you get extra features like current sensing and various protections.

- Jan

Hi Jan,

Thank you for recommending the MC33926 and for giving me your valuable advice.

Btw, what do you feel about selling a high frequency optos or integrating a few on a PCB and making a breakout board for them? Or you can also integrate them in your motor drivers, that way pololu users will have one less thing to worry about and their systems will be better protected against noise.


Basically, I don’t think noise concerns are enough of a justification for optical isolation in our typical applications. An optocoupler-only board would be difficult or expensive to make general enough since different motor drivers have different numbers of control lines going in various directions. Something like the MC33926, for instance, is quite flexible, and there could be four different lines one might legitimately want to PWM, and all this would not make sense unless we had electrically isolated current sense feedback in the other direction, at which point the isolation electronics would cost more than the rest of the parts on the board.

It might make sense for some of our more expensive drivers (some of which already have a current sensor with built-in isolation), so we’ll keep your request in mind.

I’m not sure what your project is, but it sounds like you are quite worried about noise through the I/O lines and think isolating them will help you. What is your concern/hope for this particular solution based on?

- Jan