How to read datasheets
Which is correct about the reverse recovery time trr in a diode datasheet?
- AIt is a constant inherent to the device, so it has the same value under any circuit conditions
- BIt varies with conditions such as forward current IF, the rate of current decrease di/dt and temperature, so read it together with the test conditions
- CSchottky barrier diodes generally have a longer trr than ordinary PN-junction diodes
Show answer and explanation
Answer: B. It varies with conditions such as forward current IF, the rate of current decrease di/dt and temperature, so read it together with the test conditions
trr is the time during which reverse current flows, after switching from forward conduction to reverse bias, until the stored minority carriers are swept out. The amount of stored charge varies with forward current and temperature, and the waveform also changes with how fast the current is switched (di/dt), so datasheets specify it with conditions such as "IF = 1 A, di/dt = 100 A/µs." It is on the order of µs for general-purpose rectifiers and several tens of ns for fast-recovery types. Schottky diodes operate with majority carriers, so they have almost no reverse recovery.