The Problem :

Choosing the wrong switching frequency in a MOSFET circuit can cause excessive heat and power loss. High frequencies increase switching losses, while low frequencies make the circuit inefficient.

The Solution :

To select the right switching frequency:

• Identify Load Requirements: Check voltage and current demands.

• Evaluate MOSFET Specs: Focus on gate charge (Qg) and drain-source capacitance (Cds).

• Optimal Range: For most circuits, a range between 20 kHz to 200 kHz offers the best balance between efficiency and heat management.

Practical Example :

If you’re driving a 12V DC motor using a MOSFET IRFZ44N, operating it at 50 kHz maintains efficient operation without overheating. But if the frequency increases to 200 kHz, the MOSFET may generate excess heat, requiring a heatsink.

Sample Calculation :

For a MOSFET with Qg = 63 nC and gate driver current of 500 mA:

Switching Time (t) = IQg ​= 0.563×10−9​≈126ns

At 100 kHz, the MOSFET switches efficiently with minimal power loss.

Recommended Products :

Ensure smooth switching with quality MOSFETs and gate driver ICs:

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