Voltage and current specification of MOS diode

Voltage and current specification of MOS diodee.

1. Voltage specification (VDSS).

It is commonly known as withstand voltage, which should be at least 3 times that of the main winding. It should be noted that the voltage of the main winding refers to N2 or N3 in figure 2.6, not the sum of the two. In detail, the figure is 10.5V, so the voltage specification of Q1 and Q2 is at least 31.5V. Considering 10% wavering and 1.5 times the safety factor, the voltage specification should not be lower than 31.5 X 1.1X 1.5V 52V. The voltage specification of the 2SK2313 in the figure is 60V, which meets the request.

Secondly, according to common experience, when the voltage specification exceeds 200V VMOS, the advantage of saturation on-resistance is not obvious, but the cost is much higher than the diode, and the circuit is also complex. Therefore, when used as synchronous rectifier, the maximum voltage of the main winding should not be higher than 40V.

two。. Current Specification (In).

This problem is mainly related to the maximum dissipative power. Because of the complexity of the calculation method and the need for experimental verification, it can also be confirmed directly by the theoretical method, that is, in the practical working environment, according to the most extreme maximum ambient temperature, for example, the temperature of comparable heat in summer, such as 35 ℃, according to the working current required by practice, connected with the appropriate false load, work continuously for about 2 hours. If the MOS diodee heatsink (TAB) is not hot, it can be used fundamentally. This method is rough, but it is simple and applicable.