The principle of replacing rectifier diodes

The principle of replacing rectifier diodes

What is a rectifier diode

A semiconductor device that can convert alternating current energy into direct current. rectifier diodes are widely used in various power supply rectifier circuits. When choosing a rectifier diode, we mainly consider its parameters such as reverse working voltage VR, average rectification current IF, reverse working current IR, working frequency fm, and reverse recovery time trr.

Rectifier diode replacement principle

There are both low-frequency and high-frequency power supplies. For series regulated power supplies, this is a type of power supply that continuously adjusts the voltage drop of the power transistor to obtain a stable output voltage when the input or output changes. This adjustment transistor operates in a linear amplification state, and this circuit does not require a high reverse recovery time for the rectifier diode. Therefore, this type of power supply rectifier diode only needs to meet the rectifier current. Basic requirements such as reverse working voltage and reverse working current are sufficient, such as the 1N400X series diodes that we often use.

However, for switch type regulated power supplies, stable output voltage is obtained by adjusting the conduction or cutoff of the power transistor. This is because the transistor operates in a saturated conduction state, and its rectifier circuit has a relatively high frequency for the rectifier diode used. In addition, the reverse recovery time is also required to be short. At this time, it is necessary to choose fast recovery diodes, or even Schottky diodes.

Therefore, in summary, several principles can be considered for the replacement of rectifier diodes:

① A rectifier diode with a high average rectification current can replace a diode with a low rectification current, but the opposite is not possible;

② rectifier diodes with high reverse operating voltage can replace rectifier diodes with low reverse voltage, but the reverse is not feasible;

③ rectifier diodes with high operating frequencies can replace rectifier diodes with low operating frequencies, but the opposite is not true.