I'm looking at building a circuit that is powered by the 12V power rail that is commonly provided with a desktop power supply.
What would be a good rule of thumb for what an "overvoltage" scenario would look like if a desktop power supply failed, and you wanted to protect what is powered in that circuit?
What sort of current or voltage peaks would you expect in a failure scenario for a desktop power supply?
For over-voltage protection, the easy answer is using an IC something like a LTC4360 -- but is protection up to 80V sufficient for a desktop power supply failure?
What happens when a power supply fails, that is hooked up to 120V AC source? What starts pouring out of the broken power supply? (Hopefully nothing -- right because it has some kind of over-voltage protection -- but still....?).
Do you go with a more discrete solution and add a physical fuse and a crowbar circuit of some sort (I kind of like the fuse approach personally) -- if so, what kind of parameters?
Maybe an SMD resettable fuse and a zener diode? (Seems like the cheapest way).
I don't have any experience in power supply design -- or in this case, when power supplies fail and what that transient event looks like.