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That's a good design for input overvoltage protection (assuming I've drawn the correct schematic in my head). But it doesn't help against most other fault conditions, particularly anything to do with the load/downstream going short.

Really, if you care beyond "blow the fuse if something shorts", you need active current limiting. For common cases like USB ports, you can buy chips that do it cheaply and efficiently. There are also some textbook circuits, though they each have their pros and cons. No matter what, if you've got a pass transistor or switching transistor that's about to go seriously overcurrent, you have to do something about it with active parts -- fuses aren't going to get it done.

But defense in depth is always a good strategy, and fuses play a key role there. The active circuitry saves the rest of the design; if it can't get the job done, the fuse makes sure nothing burns.

by PowerElectronix5 hours ago|

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Yeah, fuses are more of a overload protection kind of stuff. For cases where the load is trying to kill itself and you with it you need current limitation circuits, either on a converter or a latch current limiter.

Orrr you can design your circuit to survive a short condition for a bit longer than a fuse takes to blow. For old cars this was common, let whatever is short take all the current it wants for a tenth of a second and forget about it.the battery may lose a bit of useful life but those things were gonna fail early either way.

by ak2173 hours ago|

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Just want to mention how much I appreciate this discussion and the opportunity to learn from it. This is what I come to HN for (nowadays there are also really interesting YouTubers who do informative teardowns of power electronics and other devices, too e.g. Labo de Michel, Watch Wes Work, etc.)