RXEF Resettable Fuse PTC 72V @ 0.2A - (AD55231)

Description:

This is a handy little device that can keep your system from smoking. A resettable fuse (also known as a PTC) is a resistor that has unique properties.

For this model, if your circuit tries to draw more than 200mA of current (if you have a bad short circuit, for example), the PTC will 'trip' (heat up). The increase in resistance (tripped state) would break the circuit and allow only a small leakage current.

The leakage current may still be enough to damage some electronic components, but it is much lower than the 3A that the short may have allowed. By removing the short circuit, the PTC 'resets' and allows current of up to 200mA to flow again. It is a resettable fuse that protects your system! Good to use on battery-operated devices that need protection against accidental high-current discharges.

The thermal images below show very well what happens when the PTC trips. The first thermal image shows a voltage regulator circuit in its normal state. In the second image, the circuit is shorted; notice how hot the PTC is (213°F!) as it limits the amount of damaging current passing through the circuit.

Datasheet