Several parameters that must be considered when choosing Schottky diodes

Several parameters that must be considered when choosing Schottky diodes

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

1. Conduction voltage drop VF

VF is the voltage drop across the Schottky diode when it conducts in the forward direction. The larger the current passing through the diode, the greater VF; The higher the temperature of the diode, the smaller the VF.

Several parameters that must be considered when choosing Schottky diodes

2. Reverse saturation leakage current IR

IR refers to the current flowing through a Schottky diode when a reverse voltage is applied across the two ends of the diode. The reverse leakage current of the Schottky diode is relatively large, so it is recommended to choose a Schottky diode with a smaller IR as much as possible.

3. Rated current IF

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

4. Larger surge current IFSM

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

Several parameters that must be considered when choosing Schottky diodes

5. Larger reverse peak voltage VRM

Even without reverse current, as long as the reverse voltage is continuously increased, the Schottky diode will eventually be damaged. This type of reverse voltage that can be applied is not an instantaneous voltage, but a repeatedly applied forward and reverse voltage. Due to the application of AC voltage to the rectifier, its larger value is an important factor specified. A larger reverse peak voltage VRM refers to the greater reverse voltage that can be applied to avoid breakdown. The current higher VRM value for Schottky is 150V.

6. Larger DC reverse voltage VR

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