Resettable surface mount fuses are a reusable type of circuit protection device that is able to be mounted onto printed circuit boards. They trip when the current gets too high, but will function again when conditions return to an acceptable level.
Resettable surface mount fuses form part of the circuit on a PCB (printed circuit board), allowing electrical current to flow through them. When a fault such as overcurrent is detected in the circuit, they are tripped, forcing a break in the circuit which prevents electricity from continuing to flow. This prevents any damage to the circuit or attached devices. Unlike non-resettable surface mount fuses, they can be used over and over, as they will reconnect the circuit when conditions return to normal.
Resettable surface mount fuses have a number of characteristics that can vary between models, including terminal material, voltage rating and their operating temperature range. They also come in various different sizes.