fast recovery diode (FRD)

A Fast Recovery Diode (FRD) is a pn junction diode that can switch between forward and reverse operation for extremely short periods of time. In these diodes, which also include ultra fast recovery diodes and fast recovery epitaxial diodes( FRED), there is a correlation between the drop in forward voltage, reverse voltage and time. It is in this correlation (di/dt) that the various fast recovery diodes differ.

The faster switching between the forward and reverse regions, which is expressed in the turn-on and turn-off behavior and is referred to as reverse delay time, reduces the reverse current and power dissipation of the FRD diode. Fast recovery diodes are relatively robust PN diodes that are used as power diodes in switching power supplies, for example. Their reverse delay times are a few hundred nanoseconds, with Ultra Fast Recovery Diodes even around 10 ns. FRD diodes can be used up to over 1,000 volts and switch currents of several hundred amperes.

Fast Recovery Diodes also include Schottky diodes, but these are used in high and ultra- high frequency applications. The difference between the two is that Schottky diodes do not have a pn junction, but an n-metal junction.