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by exar0815 758 days ago
Some weeks ago I also relied on a 1A Quick-Blow fuse to safeguard my project from accidentally blowing up. However, while tuning the parameters for the 10 Amp 5-60V Buck Boost converter (which was only loaded output-wise for 5W at the moment) I got a thermal runaway at one of the mosfets, which instantly vaporized the FET and the FR4 below it. While my error was that the Input PSU was still set to 250W, that fuse was completely okay afterwards. Don't rely on fuses alone. They suck.
2 comments

Fuses are just not that great. Quickblow fuses cannot keep up with quickblow MOSFETs. All they can do is limit the size of the fire in your enclosure.
Specifically, fuses (I mean actual fuses) have specific specs and MOSFETS have different specific specs. There is nothing wrong with using fuses if you understand and pay attention to that spec. Indeed a "quickblow" fuse will not protect you from everything you can think of - just some things - just because it's "quickblow".
Thermal fuses (which is what pretty much everyone here is talking about) will blow in seconds for “quick blow”. (There’s a chart for overload vs time, but it’s still slow).

If you want protection you can use electrical fuses/load switches that turn off in microseconds (which still might not save the fet but should at least save the pcb)