MOSFETs are crucial in electronic circuits, especially for switching and power regulation. But if you’re a hobbyist or prototyper in India, you may have encountered an issue called thermal runaway—where a MOSFET heats up, draws more current, and keeps heating until it fails. Here’s a quick guide to help you prevent this common problem.

🌡️ The Problem: Thermal Runaway in MOSFETs

MOSFETs have a negative temperature coefficient, meaning as they get hotter, their resistance drops. This causes them to conduct more, heat up even more, and possibly burn out if left unchecked. Without proper cooling or circuit design, this can damage your entire project.

🔧 The Solution: Proper Heat Sinking & Gate Resistors

To prevent thermal runaway, use a heatsink, ensure your MOSFET operates within its Safe Operating Area (SOA), and include a gate resistor to control switching speed and minimize power dissipation. Using thermally stable MOSFETs also helps.

🧰 Practical Example: DIY Motor Controller

Say you’re building a DIY motor controller with an IRF540N MOSFET. After 10 minutes, the MOSFET gets too hot and shuts down. Adding a small heatsink and a 10Ω gate resistor lowers the switching losses, reducing the temperature significantly and preventing failure.

🧮 Sample Calculation: Power Dissipation

If your MOSFET has an R_DS(on) of 0.05Ω and carries 3A current:

P=I2×R=32×0.05=0.45W

Even this small power dissipation can cause a temperature rise if unchecked!

🛒 Product Suggestion: MOSFETs & Heatsinks

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