⚡ The Problem: High Switching Transients in MOSFETs

When switching MOSFETs rapidly in circuits like motor drivers or power converters, you might encounter voltage spikes or EMI issues. These switching transients can damage components or introduce noise, leading to unreliable performance.

🔧 The Solution: Add a Gate Resistor and Snubber

To reduce these transients, insert a gate resistor (typically 10–100Ω) to slow down the switching speed slightly and dampen ringing. For even better protection, use an RC snubber circuit across the drain-source or across the load to absorb excess energy.

🧰 Practical Example :

Imagine you’re building a DIY fan speed controller using an N-channel MOSFET. When switching it on/off rapidly, you hear buzzing or your microcontroller resets. Adding a 47Ω gate resistor and a 100Ω–100nF snubber across the drain and source can dramatically reduce the issue.

🧮 Sample Calculation :

To size a gate resistor:

Assume gate charge (Qg) = 30nC, desired turn-on time = 300ns

Gate resistor Rg = Vgs × t / Qg = 10V × 300ns / 30nC = 100Ω

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