Discrete
Fast Recovery Rectifiers
Silicon rectifiers with short reverse-recovery time for high-frequency power converters.
What is it?
Fast Recovery Rectifiers (FRRs) are silicon P-N junction diodes optimised for short reverse-recovery time (Trr), typically 35-100 ns vs ~1000+ ns for general-purpose rectifiers. Used in high-frequency power converters (>50 kHz) where slow reverse recovery would waste energy and cause voltage spikes. Compared to Schottky, FRRs handle higher reverse voltage (200-1000 V) with lower leakage at high T.
When do you need it?
- Flyback converter secondary rectifier above 100 V output.
- Boost converter output rectifier above 150 V.
- PFC (Power Factor Correction) boost diode.
- Snubber diode in inductive switching circuits.
- Any high-frequency rectifier above the practical Schottky voltage range.
How to pick the right one
- IF (Average forward current)
- Sufficient for continuous load current with thermal margin.
- VR (Repetitive Reverse Voltage)
- Choose well above the maximum reverse voltage during converter switching.
- Trr (Reverse Recovery Time)
- Shorter is better. <50 ns for switching >100 kHz; <35 ns for >250 kHz.
- QRR (Reverse Recovery Charge)
- Stored charge swept out during recovery. Lower QRR = less switching loss and lower EMI.
- VF (Forward Voltage)
- Trade-off with Trr — ultra-fast diodes have higher VF. Pick the slowest VF that meets your switching speed.
What Magnias offers
Magnias Fast Recovery Rectifier portfolio covers 1 A to 10 A at 200-1000 V VR, with Trr 35-50 ns typical, in SMA / SMB / SMC / TO-220 / TO-252 packages. Halogen-free and AEC-Q101 variants available.
Common questions
Difference between Fast, Ultra-Fast, and Super-Fast?
Industry-loose categories: Fast ~150-500 ns, Ultra-Fast ~35-100 ns, Super-Fast ~15-35 ns. Always check the datasheet number rather than the marketing name.
Can I replace a fast diode with a Schottky?
Only if the reverse voltage allows. Schottky leakage above ~100 V becomes unworkable at high temperature.
Why does Trr affect efficiency?
During reverse recovery, the diode conducts in reverse and dissipates energy. Higher switching frequency × longer Trr = more loss per second.