Electronic – USB Fuse to protect USB ports


I shorted by accident a circuit creating large voltage to my computer, luckily MBA has some sort of shorting protections — yet this kind of thing should not happen. I would like to have a fuse between my microprocessor and my computer.

What are this kind of protection mechanisms called? USB fuse did not return anything in eBay so I am thinking I am trying to find things with wrong word.

Best Answer

You're looking for a resettable fuse, PTC, or thermistor.

They're basically a resistor with low resistance in normal conditions, but as they heat up, the resistance goes up significantly. This causes a massive voltage drop, stopping the short circuit (until it cools down again). Since it has some resistance, some electricity is burned off, heating the PTC a little bit. As you increase the current, it will heat up more until it trips.