If you have an application in which a MOSFET is already used to switch a load, it is relatively easy to add short-circuit or overload protection. Here we make use of the internal resistance R DS(ON), which produces a voltage drop that depends on the amount of current flowing through the MOSFET. The voltage across the internal resistance can be sensed using simple comparator or even a transistor, which switches on at a voltage of around 0.5 V. You can thus avoid the use of a sense resistor (shunt), which usually produces an undesirable extra voltage drop.
Short-Circuit Protection Circuit Diagram
The comparator can be monitored by a microcontroller. In case of an overload, the software can initiate suitable countermeasures (PWM regulation, alarm, emergency stop etc.). It is also conceivable to connect the comparator out-put directly to the gate of the MOSFET, in order to immediately cut off the transistor in case of a short circuit.