Advanced Reverse Recovery Time Calculator

Model reverse decay using measured test data. Review storage time, tail time, charge, and softness. Make better rectifier selections for demanding high-speed switching applications.

Calculator Inputs

Choose a calculation method, enter available diode test data, and submit. Results appear above this form and directly below the page header.

Select the best method for your available test data.
nC
Used in the charge-based method.
A
Peak negative recovery current.
tb/ta
Higher values indicate softer recovery.
A/µs
Used in the slope-based method.
ns
Time from zero crossing to peak reverse current.
ns
Time from peak reverse current back to zero.
V
Optional for energy loss estimation.
kHz
Optional for average recovery power loss.

Formula Used

1) Total reverse recovery time

trr = ta + tb

The total recovery time is the sum of the interval to peak reverse current and the interval back to zero current.

2) Charge-based model

Qrr = 0.5 × Irrm × trr

trr = 2 × Qrr / Irrm

S = tb / ta

ta = trr / (1 + S), tb = S × ta

3) Slope-based model

ta = Irrm / (di/dt)

tb = S × ta

trr = ta + tb

4) Recovery loss estimate

Err ≈ Qrr × VR

Prr = Err × fsw

How to Use This Calculator

  1. Choose the method that matches your available diode test data.
  2. Enter peak reverse current for all methods.
  3. Enter Qrr and softness for the charge method.
  4. Enter di/dt and softness for the slope method.
  5. Enter ta and tb directly if timing data is known.
  6. Add reverse voltage and switching frequency for loss estimation.
  7. Press Submit to display results above the form.
  8. Review the waveform plot, result table, and design note.
  9. Use the export buttons to save CSV or PDF output.

Example Data Table

Case Method Qrr (nC) Irrm (A) S ta (ns) tb (ns) trr (ns)
Fast rectifier A Charge + softness 60 3.5 0.8 19.048 15.238 34.286
Ultrafast diode B Slope + softness 96 4.0 1.4 20.000 28.000 48.000
Measured sample C Direct time entry 100 5.0 1.5 16.000 24.000 40.000

FAQs

1) What is reverse recovery time?

Reverse recovery time is the interval a diode needs to stop conducting after current reverses. It includes the rise to peak reverse current and the return to zero current.

2) Why does softness factor matter?

Softness describes how quickly current decays after the reverse peak. A harder recovery may increase ringing, voltage overshoot, and EMI in fast-switching power circuits.

3) Which calculation method should I use?

Use charge plus softness when Qrr data is available, slope plus softness when di/dt is known, and direct time entry when oscilloscope timing intervals are already measured.

4) Does a higher di/dt always improve performance?

Not always. A steeper current slope can shorten ta for a fixed peak current, but it may also worsen stress, switching noise, and circuit overshoot.

5) Can this tool estimate switching loss?

Yes. When you provide reverse voltage and switching frequency, the calculator estimates recovery energy per event and average recovery power loss.

6) Why are nanoseconds used for trr?

Many fast and ultrafast diodes recover very quickly, so nanoseconds are practical for reading datasheets, comparing parts, and plotting measured switching behavior.

7) Is the triangular Qrr approximation exact?

No. It is a useful engineering approximation. Real recovery waveforms can curve, distort, or ring, so measured data remains the best reference.

8) How does temperature affect recovery?

Higher junction temperature often increases stored charge, reverse recovery time, and recovery loss. Always compare calculations against the intended operating temperature range.

This engineering tool provides estimation support for diode switching analysis. Validate critical designs with device datasheets, lab measurements, and full converter simulations.

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Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.