Fast Recovery Diode Detection Method and Trouble Cause Analysis

Fast Recovery Diode Detection Method and Trouble Cause Analysis

Fast recovery diode (FRD for short) is a semiconductor diode with good switching characteristics and short reverse recovery time. It is mainly used in electronic circuits such as switching power supplies, PWM pulse width modulators, and frequency converters. Freewheeling diodes or damping  diode are used. The fast recovery diode adopts gold-doped, simple diffusion and other processes in the manufacturing process, which can obtain high switching speed and high withstand voltage at the same time. At present, fast recovery diodes are mainly used as rectifying elements in inverter power supplies.

Routine detection method of Fast Recovery Diode 

1. Put the multimeter in the Rx1k position and measure the forward and reverse resistance of the fast recovery  diode. The forward resistance is generally a few ohms, and the reverse resistance is ∞. If the measured resistance values are all ∞ or 0, it means that it is The measuring tube is damaged.

2. The detection method of Fast Recovery Diode  is basically the same as the above method, but it must first determine which pin the common terminal is, and then use the above method to test each fast recovery  diode.

Notes onFast Recovery Diode :

1) Some single tubes have three pins in total, and the middle one is empty, which is usually cut off when leaving the factory, but some don't.

2) If one of the paired tubes is damaged, it can be used as a single tube.

3) When measuring the forward conduction voltage drop, the R×1 file must be used. If the R×1k file is used, the measured VF value will be obviously low because the test current is too small, far lower than the normal working current of the tube. In the above example, if the R×1k file is selected for measurement, the forward resistance is equal to 2.2kΩ, and n′=9 divisions at this time. The calculated VF value is only 0.27V, which is much lower than the normal value (0.6V).

Cause Analysis of Fast Recovery Diode  Faults

1. The voltage used is too high, exceeding the reverse breakdown voltage of the Fast Recovery Diode , and it is broken down.

2. The current is too large. The current through the Fast Recovery Diode  exceeds its rated current for a long time, and it is overheated and burned. This is a relatively common reason.

3. The purchased low-frequency  diode are used in high-frequency circuits, causing the diodes to overheat and burn out.

4. The specifications and models of fast recovery diodes do not match. When replacing a new diode, the tube whose working parameters do not meet the requirements is mistakenly replaced or the wiring is wrong, resulting in breakdown and damage to the  diode tube.

Fifth, the circuit board is short-circuited. After cleaning the circuit board with steam, it is not dried, which is caused by the circuit short-circuit fault caused by water. After cleaning with steam, blow it with compressed air and check again should avoid this kind of damage.

The above is the whole content of "Fast Recovery Diode  detection method and failure cause analysis", I hope it will be helpful to everyone.