FRDs (Fast Recovery Diodes)

The structure and function of fast recovery diodes (FRDs) are the same as those of rectifier diodes. Rectifier diodes are used for low-frequency applications below 500 Hz, whereas FRDs are used for high-frequency switching from a few kHz to 100 kHz. Therefore, the reverse recovery time (trr) of the diode characteristic, which is important for high-speed switching, is short. FRDs are also referred to as S-FRDs, HEDs, etc. according to the trr value.
trr of a general rectifier diode is several μs to several tens of μs. On the other hand, trr of an FRD is several tens of ns to several hundred ns and is about 1/100 of that of the rectifier diode. It is used in switching power supplies, inverters, DC/DC converters, etc.

FRDs (Fast Recovery Diodes)

Fig. 2-3(a) Example of diode switching waveform and loss

Fig. 2-3(b) Comparison of trr between general-purpose rectifier and FRD

The loss due to trr (reverse recovery loss) is negligible when the frequency is low, but this loss increases with frequency, and it cannot be ignored if it becomes several kHz or more.

Chapter II : Diodes

Types of Diodes
Functions of Rectifier Diodes
Forward Characteristic of Rectifier Diodes (IF-VF Characteristic)
Voltage Regulator Diodes (Zener Diodes)
TVS diode (ESD protection diode)
Difference between TVS Diodes and Zener Diodes (1)
Difference between TVS Diodes and Zener Diodes (2)
Variable-capacitance Diodes (Varicap Diodes)
Schottky Barrier Diodes (SBDs)
Reverse Recovery Characteristic of Schottky Barrier Diodes (SBDs)
Difference Depending on Metal of Schottky Barrier Diodes (SBDs)
Characteristics Application of Various Diodes

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