I want to use a 24V to 5V DC converter, the PYBJ10-Q24-S5 (https://www.mouser.fr/datasheet/2/670/pybj10-om-1548233.pdf).

Page 7 of the datasheet, they specified the EMC Recommended Circuit which includes the fuse I'm trying to choose.

If I understood correctly the datasheet, the converter accepts a maximum input current of 508mA and has a current overload protection of at least 110%.

So if I'm correct, in the worst case scenario it should not exceed 558mA.

I was planning to use a resettable fuse. If I understood correctly, the holding current is the maximum current such as the fuse won't trip.

The tripping current is the minimum current such as the fuse will trip.

In conclusion, I have to choose a resettable fuse with a holding current = 508mA and a tripping current = 558mA.

Problem is : in this configuration, I can't find exactly the right fuse.

Knowing all this, how do I choose my fuse from all the existing models?

For example, I found some fuses with currents of 550mA versus 1A but I'm afraid that 1amp is much too high for my converter.

I guess I'm missing something.