⚠️ The Problem: MOSFETs Failing Due to Overcurrent

MOSFETs are widely used in DIY and professional electronics projects to control high current loads. But without proper protection, they can burn out due to overcurrent conditions, such as motor stall or short circuits. Beginners often forget that a simple wiring mistake or unexpected load spike can damage even high-rated MOSFETs.

🛠️ The Solution: Add Current Sensing & Limiting

One of the easiest and most effective solutions is using a current sense resistor (low-value shunt resistor) in series with the MOSFET’s source. You can monitor the voltage drop across it to detect overcurrent and shut down the gate using a comparator or microcontroller.

🔍 Practical Example: Protecting a Motor Driver Circuit

A hobbyist in Hyderabad was driving a DC motor with an IRFZ44N MOSFET. During a stall, the MOSFET heated up and failed. After adding a 0.1Ω resistor in series and feeding its voltage to an Arduino analog pin, he could shut off the gate if current exceeded 5A. Problem solved!

📐 Sample Calculation: Current Sense Resistor Value

Desired trip current = 5A

Voltage drop = 0.5V ⇒

R = V/I = 0.5V / 5A = 0.1Ω

Use a 0.1Ω, 2W resistor and monitor it via ADC or comparator logic.

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