MOSFET Switching Loss Tuning – A DIY Guide
⚠️ The Problem :
When a MOSFET turns on or off, there’s a brief moment where both voltage and current are non-zero—this causes switching loss. At high frequencies, these losses can heat up your circuit and reduce efficiency, especially in SMPS and motor drivers.
🛠️ The Solution :
To control switching speed and reduce losses, insert a gate resistor (10Ω–100Ω) between the driver and gate. It slows down the charging and discharging of the gate, balancing between switching speed and loss. Too fast = EMI; too slow = more loss. Tuning helps optimize both!
💡 Practical Example :
In a BLDC motor controller switching at 50kHz, using an IRF540N without a gate resistor caused excessive heating. Adding a 22Ω gate resistor reduced MOSFET heating by over 30%, while maintaining stable performance and minimal EMI.
✏️ Sample Calculation :
Gate charge (Qg) = 67nC, Vgs = 10V, R<sub>gate</sub> = 22Ω:
This value helps estimate switching energy and optimize timing.
🛒 Product Suggestion :
Search for ‘MOSFET IRF540N’ or ‘gate resistor 22 ohm’ here:
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