In electronics, MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors) are widely used in switches and amplifiers. However, they are sensitive to short circuits, which can cause damage or failure. When a short circuit occurs, excessive current flows through the MOSFET, potentially burning out the component.

To fix this issue, adding a short-circuit protection circuit can help. A simple method is using a current-sensing resistor (also known as a sense resistor) and a comparative circuit like an op-amp. If the current exceeds a safe threshold, the circuit will quickly turn off the MOSFET, preventing damage.

The Problem :

Imagine you are building a motor controller for a robotics project. You connect a MOSFET to control the motor’s power. If the motor experiences a stall (a short-circuit condition), it can draw excessive current, damaging the MOSFET. By adding a current-sensing resistor between the MOSFET and the motor, and setting up a comparator circuit to monitor the voltage drop across the resistor, the MOSFET will be cut off if the current gets too high.

Sample Calculation:

If you want to trigger the cutoff at 1A, and you choose a 0.1Ω resistor, the voltage across it will be:

V = I × R = 1A × 0.1Ω = 0.1V.

This voltage can be fed to the comparator to trigger the shutdown.

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