What Is a Fast Recovery Diode?
1 min read
Quick answer
A fast recovery diode is a power diode with a very short reverse recovery time (trr). It replaces the standard diode in high-frequency switching circuits.
What Is Reverse Recovery Time (trr)?
As a diode goes from conducting to blocking, for a brief moment it also passes current in the reverse direction; during this time it "recovers". This interval is called trr. It's long in standard diodes and very short in fast-recovery ones.
Why Does It Matter?
At high frequency a diode changes direction thousands of times per second. A long trr means power loss (heat) and noise on every transition; a short trr minimizes this and improves efficiency.
Comparison With Schottky
| Property | Schottky | Fast Recovery |
|---|---|---|
| Speed | Fastest | Fast |
| Voltage rating | Low | High |
| Use | Low-voltage SMPS | High-voltage SMPS |
Where Is It Used?
Switch-mode power supplies (SMPS), inverters, motor drives and high-voltage high-frequency circuits.
Common Mistakes
- Using a standard diode: a slow diode overheats at high frequency and drops efficiency.
- Ignoring trr: a trr matched to the frequency is essential when choosing a diode.
- Confusing it with Schottky: if high voltage is required, fast recovery — not Schottky — is the fit.
Frequently Asked Questions
Schottky or fast recovery?+
For low voltage the Schottky is faster and more efficient; for high voltage the fast-recovery diode is the fit.
Why is a small trr good?+
Less loss and noise on every switching transition; efficiency rises at high frequency.
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