MOSFET body-diode and dead-time loss

Assumptions to check

• The entered MOSFET-body-diode-loss values represent the stated operating condition.
• This standard approximation is evaluated in the declared lumped or first-pass model.
• A MOSFET-body-diode-loss calculation is not a component qualification or safety approval.

What this MOSFET-body-diode-loss calculation establishes

Estimate average MOSFET body-diode conduction loss during the switching dead-time interval each cycle. The useful result is the stated electrical quantity and the decision it supports, not an unstated claim about a finished product. This engine keeps the governing relationship visible so an input, unit, condition, or model boundary can be reviewed before a value becomes a component or layout choice.

Average dead-time conduction loss is current times body-diode forward voltage times dead time times switching frequency, for one conduction event per cycle. Treat the number as a first-pass result for the declared operating point. When a source, load, temperature, frequency, waveform, component tolerance, or measurement condition changes, repeat the calculation at the relevant corner rather than assuming the nominal answer persists.

Worked decision context

10 A, Vf = 0.8 V, 100 ns dead time, and 100 kHz give 80 mW average loss for one dead-time conduction interval per cycle. That example verifies the equation and illustrates the scale of the result, but it does not select a part by itself. Compare the result with available values, ratings, tolerance bands, and the receiving circuit or physical environment before implementation.

Use the primary output to identify the binding constraint. If it leaves little margin, document which input dominates and use selected-part data, a higher-fidelity model, simulation, or measurement. This is especially important when a small numerical difference changes a thermal, timing, noise, or reliability decision.

Limits and validation handoff

This estimates one conduction interval per cycle. Reverse-recovery charge energy, multiple dead-time events per cycle, and temperature-dependent Vf are separate terms to add. The calculation does not silently include omitted parasitics, installation conditions, manufacturing variation, or product policy. Those conditions can be decisive even when the arithmetic is exact for the selected model.

Record inputs, units, model assumptions, and the intended decision with the result. Verify the leading risk against the selected component data sheet and a representative measurement when the circuit has consequential energy, high voltage, safety, compliance, or reliability requirements.

Common mistakes

• Treating the MOSFET-body-diode-loss result as a guaranteed operating limit rather than a first-pass standard approximation estimate.
• Mixing a data-sheet value measured under one condition with this MOSFET-body-diode-loss calculation performed at another.
• Selecting a component before checking the boundary this calculation names: this estimates one conduction interval per cycle. Reverse-recovery charge energy, multiple dead-time events per cycle, and temperature-dependent Vf are separate terms to add.

Model limit and handoff

Keep the entered MOSFET-body-diode-loss conditions with the calculation, then validate the binding limit using the selected component, physical implementation, and representative operating corner.

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