Diode Reverse-Recovery Loss
P = Qrr · Vin · fsw
Quick answer
This calculator solves P = Qrr × Vin × fsw for Power Loss. With Recovery Charge 10 nC, Switching Voltage 12 V, Switching Frequency 100 kHz, the result is 12 mW. It solves in 4 directions, so you can enter the values you have and get the one you need.
Calculator
Formula
Description
When a diode (or a MOSFET’s body diode) is forced off, the stored minority-charge Qrr must be swept out, briefly shorting the supply through the opposing switch. The energy lost each cycle is roughly the recovery charge times the voltage, and it scales with frequency. In hard-switched synchronous and bridge converters this can be one of the largest loss terms.
Variables
- P — Reverse-recovery loss (W)
- Qrr — Reverse-recovery charge (C)
- Vin — Voltage across the diode when it recovers (V)
- fsw — Switching frequency (Hz)
Practical Notes
Use fast/soft-recovery or Schottky diodes (near-zero Qrr) to cut this loss. It is why GaN and SiC devices, with little or no reverse recovery, excel at high-frequency hard switching.
Symbols and units
| Symbol | Meaning | Default unit | Accepted units |
|---|---|---|---|
| P | Power Loss | mW | µW, mW, W, kW |
| Qrr | Recovery Charge | nC | pC, nC, µC, mC, C |
| Vin | Switching Voltage | V | pV, nV, µV, mV, V, kV |
| fsw | Switching Frequency | kHz | Hz, kHz, MHz, GHz |
Step by step
- 1. What you know: Recovery Charge 10 nC, Switching Voltage 12 V, Switching Frequency 100 kHz
- 2. The relation: P = Qrr × Vin × fsw
- 3. Substitute: Qrr = 10 nC, Vin = 12 V, fsw = 100 kHz
- 4. Result: Power Loss = 12 mW
Worked examples
Minimum range
Given: Recovery Charge 100 pC, Switching Voltage 0.33 V, Switching Frequency 100 Hz
Result: Power Loss = 0.0033 µW
Low range
Given: Recovery Charge 1 nC, Switching Voltage 3.3 V, Switching Frequency 1 kHz
Result: Power Loss = 3.3 µW
Typical
Given: Recovery Charge 10 nC, Switching Voltage 12 V, Switching Frequency 100 kHz
Result: Power Loss = 12 mW
High range
Given: Recovery Charge 100 nC, Switching Voltage 0.23 kV, Switching Frequency 0.5 MHz
Result: Power Loss = 11.5 W
Maximum range
Given: Recovery Charge 1 µC, Switching Voltage 2.3 kV, Switching Frequency 5 MHz
Result: Power Loss = 11.5 kW
Solving for each variable
Solve for Power Loss
Recovery Charge 100 pC, Switching Voltage 0.33 V, Switching Frequency 100 Hz → 0.0033 µW
Solve for Recovery Charge
Power Loss 100 µW, Switching Voltage 0.33 V, Switching Frequency 100 Hz → 3.03 µC
Solve for Switching Voltage
Power Loss 100 µW, Recovery Charge 100 pC, Switching Frequency 100 Hz → 10 kV
Solve for Switching Frequency
Power Loss 100 µW, Recovery Charge 100 pC, Switching Voltage 0.33 V → 3.03 MHz
How Power Loss changes with Recovery Charge
| Recovery Charge (input) | Power Loss (result) |
|---|---|
| 1 nC | 1.2 mW |
| 2.5 nC | 3 mW |
| 5 nC | 6 mW |
| 7.5 nC | 9 mW |
| 10 nC | 12 mW |
| 15 nC | 18 mW |
| 20 nC | 24 mW |
| 40 nC | 48 mW |
| 70 nC | 84 mW |
| 100 nC | 120 mW |
The same result in other units
| Unit | Value |
|---|---|
| µW | 12000 |
| mW | 12 |
| W | 0.012 |
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<p><a href="https://vbatpower.com/formulas/mosfet-qrr-loss/">Diode Reverse-Recovery Loss</a> Calculator by vbatpower.com</p>Frequently asked questions
How do you calculate Diode Reverse-Recovery Loss?
Use P = Qrr × Vin × fsw. With Recovery Charge 10 nC, Switching Voltage 12 V, Switching Frequency 100 kHz, Power Loss works out to 12 mW.
How do you calculate diode reverse recovery loss calculation?
Rearrange for Power Loss: with Recovery Charge 1 nC, Switching Voltage 3.3 V, Switching Frequency 1 kHz, Power Loss is 3.3 µW.
What is the formula for Diode Reverse-Recovery Loss?
The formula is P = Qrr × Vin × fsw. When a diode (or a MOSFET’s body diode) is forced off, the stored minority-charge Qrr must be swept out, briefly shorting the supply through the opposing switch.
How do you find Recovery Charge when you know the other values?
Rearrange for Recovery Charge: with Power Loss 100 µW, Switching Voltage 0.33 V, Switching Frequency 100 Hz, Recovery Charge is 3.03 µC.
How do you find Switching Voltage when you know the other values?
Rearrange for Switching Voltage: with Power Loss 100 µW, Recovery Charge 100 pC, Switching Frequency 100 Hz, Switching Voltage is 10 kV.
What units does Diode Reverse-Recovery Loss use?
Power Loss is shown in µW, mW, W. Values are held in SI base units internally, so you can mix prefixes without converting by hand.
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