Several parameters that must be considered when selecting Schottky diodes

Several parameters that must be considered when selecting Schottky diodes

In switching power supplies, we often use Schottky diodes, but due to different manufacturers and other reasons, the performance varies greatly. When choosing Schottky diodes, we must consider the following parameters:

1. Conduction voltage drop VF

VF is the voltage drop at both ends of the Schottky diode when it conducts forward. The greater the current passing through the diode, the greater the VF; The higher the diode temperature, the smaller the VF.

Several parameters that must be considered when selecting Schottky diodes

2. Reverse saturated leakage current IR

IR refers to the current flowing through the Schottky diode when a reverse voltage is applied at both ends of the diode. The Schottky diode has a high reverse leakage current, so choosing a Schottky diode is to try to choose a Schottky diode with a smaller IR.

3. Rated current IF

The average current value calculated based on the allowable temperature rise during long-term operation of Schottky diodes

4. Greater surge current IFSM

Excessive forward current allowed to flow. It is not a normal current, but an instantaneous current, which is quite large.

Several parameters that must be considered when selecting Schottky diodes

5. Larger reverse peak voltage VRM

Even if there is no reverse current, as long as the reverse voltage is continuously increased, sooner or later the Schottky diode will be damaged. The reverse voltage that can be applied is not an instantaneous voltage, but a repeatedly applied forward and reverse voltage. Due to the AC voltage applied to the rectifier, its larger value is a specified important factor. The larger reverse peak voltage VRM refers to the larger reverse voltage that can be applied to avoid breakdown. Currently, Schottky higher VRM value is 150V.

6. Larger DC reverse voltage VR

The larger reverse peak voltage mentioned above is the peak voltage repeatedly applied, while VR is the value obtained by continuously applying DC voltage. For DC circuits, a larger DC reverse voltage is important for determining allowable and upper limits.

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