The Problem: High Switching Loss in MOSFETs

When switching MOSFETs at high frequency in power supplies or motor drivers, significant energy loss can occur during the transition from ON to OFF and vice versa. This is called switching loss, and it leads to excess heat, inefficiency, and even circuit failure.

The Solution: Minimize Transition Time and Gate Resistance

To reduce switching loss, ensure faster transitions. This can be achieved by choosing MOSFETs with lower gate charge and using suitable gate resistors or dedicated gate driver ICs. This allows the MOSFET to switch cleanly without spending too much time in the linear region.

Practical Example: Switching a 12V Load at 100kHz

Suppose you use a MOSFET to switch a 12V motor at 100kHz. A slow gate signal causes it to spend time in its linear region, heating up. Using a gate resistor of 10Ω with a low-Qg MOSFET and a gate driver can reduce loss and improve performance.

Sample Calculation

Switching Loss ≈ 0.5 × V × I × t × f

If V = 12V, I = 2A, t = 100ns, f = 100kHz

Loss ≈ 0.5 × 12 × 2 × 100e-9 × 100,000 = 0.12W

Reducing t to 50ns cuts this to 0.06W, halving the heat!

Product Suggestion

MOSFET

Gate Driver IC

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