The best way: simply don't use a Pi5. Use a CM5 and design the USB2 port so it doesn't draw power at all Make your USB device self-powered - the USB standard allows for that, for example for laser printers with a standard USB-B port. Separating data and power is easy on a CM5.
And note: An USB device must never backfeed any power into the host.
That's what the spec says. But a lot of self powered devices/hubs do just that. Especially the cheap ones. It seems that those who own the trademarks and set the standards don't much care about enforcing them.
An alternative would be to modify the USB cable to mask or cut the VBUS lines.
Statistics: Posted by thagrol — Fri Nov 14, 2025 4:53 pm