1. What is MOSFET Loss?

MOSFET power loss consists of conduction losses (I²R) and switching losses. These losses determine the heat dissipation requirements and efficiency of power electronic circuits using MOSFETs.

2. How Does the Calculator Work?

The calculator uses the MOSFET loss equation:

Where:

• \( R_{ds(on)} \) — Drain-source on-resistance (Ω)
• \( I \) — Current through MOSFET (A)
• \( P_{switching} \) — Switching losses (W)

Explanation: The equation accounts for both conduction losses (proportional to current squared) and switching losses (from turn-on/turn-off transitions).

3. Importance of MOSFET Loss Calculation

Details: Accurate MOSFET loss calculation is crucial for thermal design, efficiency estimation, and reliability prediction in power electronics applications.

4. Using the Calculator

Tips: Enter R_ds(on) in ohms, current in amps, and switching losses in watts. All values must be non-negative.

5. Frequently Asked Questions (FAQ)

Q1: What affects R_ds(on)?
A: R_ds(on) varies with gate voltage, temperature, and current. Use datasheet values for your operating conditions.

Q2: How to estimate switching losses?
A: Switching losses depend on frequency, gate drive, and parasitic elements. They can be measured or calculated using: P_sw = 0.5 × V × I × (t_r + t_f) × f_sw

Q3: What are typical MOSFET losses?
A: Losses range from milliwatts in small signal MOSFETs to tens of watts in power applications. Proper heatsinking is critical for high-power designs.

Q4: How to reduce MOSFET losses?
A: Use MOSFETs with lower R_ds(on), optimize gate drive, reduce switching frequency, or implement soft-switching techniques.

Q5: When is conduction loss dominant?
A: Conduction loss dominates at high duty cycles and low switching frequencies, while switching loss dominates at high frequencies.