[cdavoren]

This is a great idea. Unfortunately, I think I remember one of my electronics lecturers at uni telling us that generally communication/feedback with power supplies is dangerous because you introduce the possibility of unexpected power surges propagating in the other direction. It's apparently very hard/expensive to have both communication and protection against this. I'd love for someone to correct me, especially as this might not apply to the newer designs.

[mindslight]

An optocoupler will isolate the communications themselves, but perhaps he was referring to the fact that the overvoltage 'crowbar' circuit would need to be software controlled. Overvoltage protection shuts down the power supply when the output voltage rises too high - say if the FET gets stuck on.

OTOH one could put additional protection downstream in the load itself, and the PS would just need a well-known fixed overvoltage. If the "5V" PS started outputting 15V (but still under the PS max), the device would just shut down. However, don't expect manufacturers to do this on their own - as the article says, $1 is "expensive".