Reduce switching losses. Improve efficiency. Protect your system.
What Is Reverse Recovery?
When a diode switches from conducting (forward-biased) to blocking (reverse-biased), it doesn’t turn off instantly. Stored charge within the device must first be removed, creating a brief reverse current spike known as reverse recovery.
What Happens During Reverse Recovery
Key parameters:
- Reverse Recovery Time (trr): Time required for the diode to stop conducting
- Peak Reverse Current (Irrm): Maximum reverse current during recovery
- Recovered Charge (Qrr): Total charge that must be removed
Why it matters: The longer and larger the recovery, the greater the energy loss and stress on surrounding components.
Why Reverse Recovery Impacts Power Modules
- Switching Losses
During recovery, both current and voltage are present across the device—creating power loss.
- Higher Qrr = higher energy dissipation
- Reduces overall system efficiency
- Voltage Spikes & EMI
Rapid current changes (di/dt) during recovery interact with circuit inductance, causing:
- Voltage overshoot
- Ringing and oscillations
- Increased electromagnetic interference (EMI)
- Stress on Switching Devices
In IGBT- or MOSFET-based systems, the switching device must handle the diode’s reverse recovery current.
- Increased thermal stress
- Higher risk of device failure
- Reduced reliability over time
- Efficiency and Thermal Impact
- More losses = more heat
- Requires larger heat sinks or cooling systems
- Limits power density in compact designs
Where It Matters Most
- Inverters (motor drives, HVAC systems)
- UPS systems and power supplies
- Renewable energy (solar, wind converters)
- Electric vehicles and charging systems
Technology Comparison
|
Diode Type |
Reverse Recovery Performance |
Typical Use |
|
Standard PN Diode |
Slow, high Qrr |
Low-frequency applications |
|
Fast Recovery Diode |
Improved trr, moderate Qrr |
General power electronics |
|
Ultra-Fast Diode |
Low trr, lower Qrr |
High-frequency switching |
|
Silicon Carbide (SiC) Diode |
Near-zero reverse recovery |
High-efficiency, high-frequency systems |
Best Practices to Minimize Impact
Use Low-Qrr or SiC Diodes
Silicon carbide diodes virtually eliminate reverse recovery losses.
Optimize Switching Speed
Balance switching speed to reduce excessive di/dt and voltage spikes.
Minimize Parasitic Inductance
- Short, tight PCB layouts
- Proper busbar design
Add Snubber Circuits
Dampen voltage spikes and ringing.
Thermal Design Matters
Ensure adequate cooling for both diodes and switching devices.
Reverse recovery is a small-time event with big consequences. Managing diode behavior is essential for improving efficiency, reducing stress, and enabling high-performance power module design.
