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Noise Isolation with PWM

I am currently using a Teensy to control a 24V motor using a TB9051FTG driver. I’m using the USB 5V power as the VCC, Teensy GND pin for ground, and digital output pins for the PWM. The teensy is connected via usb to a computer that also connected via usb to electronic signal recording equipment. DC motor noise seems to be back-propagating through usb to my recording equipment, including some high voltage spikes.

What would be a good way to electrically isolate this setup? Maybe power the driver using the motor power using a 24V->5V converter, and connect to the teensy PWM signal using an opto-isolator?

I’m also curious how I could suppress some of this noise (without interfering with the PWM power output).


Using a regulator to supply 5V power off of the motor supply and opto-isolating PWM should help a lot. I think just changing the 5V supply would go a long way. You could also try adding a ferrite choke to your PWM wire and/or your USB cable (and anything else that might transfer noise).

If you are not certain the noise is coming through the USB, you might try running your motor from the Teensy while it is disconnected from USB and seeing how much that helps.