Electrical – Do I need USB isolator for laptop computer

opto-isolatorusb hub

I have a product which is powered from main AC power. I need to serial communicate the product with a computer, for example sending some bytes to the product by the terminal program in the computer. I have a USB-to-UART converter to communicate with the product. However I worry that the AC power from the product will damage my computer's USB port. If I am using a laptop computer powered by the battery (not the AC main), do I still need a USB isolator to connect the USB-to-UART converter to my laptop computer?

Please provide reason instead of just answering yes or no.
Thank you very much.

Best Answer

I suggest you consider isolating the RS-232 as @Ignacio suggests. You can even buy a packaged single-chip solution that actually includes internal transformers for signal and power isolation:

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A USB port in your unit with a connection to the mains is an extremely dangerous thing to manufacture- someday someone may plug something into that plug that will kill them or destroy a desktop computer.

With a laptop computer, depending on how it connects to the mains, touching the shell on another USB plug or headphone jack etc. when removing it or plugging it in could kill someone. This has happened for real, it is not just a theoretical risk.

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