Diode Reverse Recovery Loss

Estimate switching loss caused by diode reverse recovery using Qrr, trr, current, reverse voltage, and switching frequency.

How to Use

  1. Enter diode data from the datasheet: Qrr and (optional) trr.
  2. Enter operating conditions: forward current, reverse voltage, and switching frequency.
  3. Choose a loss model (Qrr-based energy, or trr-based shape model).
  4. Open Show Work to see the steps and assumptions in base units.
Switching Loss View
Visual feedback: recovery charge + energy per event + power at frequency.
Qrr
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Err/event
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Prr
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Model
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Risk: —
Concept: reverse recovery current pulse area ≈ Qrr Use datasheet values at your IF and di/dt when possible. t I 0 A Qrr (area) — trr Loss estimate depends on VR overlap during recovery and switching conditions.
Inputs & Settings
Enter what you know. Qrr-only model works without trr.
Datasheet value at a specified IF, di/dt, and temperature.
Used for triangle/trapezoid models; leave blank if unknown.
Current flowing just before the diode is forced off.
Approximate voltage across the diode during recovery overlap.
Power ≈ energy per event × switching frequency.
If provided, tool can apply a simple scaling factor (model-dependent).
Often used to approximate partial overlap vs worst-case (engineering estimate).
If known, triangle/trapezoid models can use it for shape/area checks.
Show Work (step-by-step)
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Work is shown in base units (C, s, V, A, J, W) for clarity and consistency.

Reference (Models)

Reverse recovery loss is primarily switching loss caused by charge removal when a diode transitions from forward conduction into reverse bias during commutation.

  • Energy from charge (common quick model): Err ≈ Qrr × VR
  • Average power: Prr ≈ Err × fSW
  • Triangle area (shape model): Qrr ≈ 0.5 × IRM × trr
  • Trapezoid area (shape model): Qrr ≈ (IRM × trr) × k (k depends on waveform)
Datasheet conditions matter: Qrr and trr vary with IF, di/dt, VR, and temperature. Use matching conditions when possible.

FAQ

What’s the difference between Qrr and trr?

Qrr is total recovered charge (area under the reverse recovery current pulse). trr is a timing metric. Two diodes can have similar trr but very different Qrr (and loss).

Why does reverse recovery create loss?

During commutation, current can flow while the diode is reverse-biased, creating overlap between current and voltage. That overlap is energy per event.

Do Schottky diodes have reverse recovery?

Schottkys typically have very low stored charge (much lower Qrr), but they can have junction capacitance and leakage. In many cases, switching loss is dominated by capacitance instead of stored-charge recovery.

Is E ≈ Qrr × VR always correct?

It’s a common quick estimate. Real loss depends on the switching node waveform, overlap timing, and how VR rises during recovery. Use it as an engineering estimate unless you have measured waveforms.

Tool Info

Last updated:

Updates may include model refinements, unit support, and edge-case handling.