Chapter · Power and protection
Fuses and current limits
A short circuit is the load going to nearly zero ohms. Two parts stand between that and your supply, and they are not remotely equally fast.
- 01Fuses and PPTCs7 minA polyfuse is a resistor that is allowed to get hot, and everything good and bad about it follows from that. It resets itself, it never quite comes back, and it is thousands of times too slow to save a transistor.
- 02A current-limiting load switch8 minA current-limiting load switch is a MOSFET with a sense loop around it, and it does in microseconds what a polyfuse does in a tenth of a second. One resistor sets the limit, and the same pin gives you an on-off control you did not have before.
Start at 01 and read down — the order is the order things get easier in. Or take the one with your part in it; every article stands on its own, and links back to whatever it needs.