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Motor control: Mixing 48V and 5V on same PCB


I'm making a little PCB to control a motor which needs 48VDC to power it. The application is to connect to a little motion stage that I'm making as a hobby machine. I've got to get power and data to the motor, so was going to use a ribbon cable to handle the bending and accommodate the motion of the axis.
Now, I'm a little bit worried about putting the 48V supply on the same PCB as the 5V supply, microcontroller and other electronics because I don't want to fry anything by mistake.

What is considered good practice in this case? Is it OK to mix voltage levels on the same board, and is there something that I can use to protect the chips incase something goes wrong? I've separated the ground planes for the two supplies, apart from a small cross-link next to the 5V regulator.


No problem as long as proper clearance is maintained.

As an added safety you can put clamping diodes (zener or supply-ground) at all the interfaces between the two "subsystems".
Pay attention at ground, since maybe some relatively fast changing signals must cross the boundary between the two ground portions (as Dave says, ground is "guilty until proven innocent").


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