Why are there two types of rated currents for power inductors?

2022.9.2 Articles GOTREND Technology Co.,Ltd

In recent years, in the world's large-scale energy-saving trend, the low-power requirements for electronic devices are also increasing, and power supply design technology has become increasingly important. In the actual power supply design, the choice of inductor is particularly critical. In DC-DC converters, inductors are the core component second only to ICs. By selecting the appropriate inductor, a high conversion efficiency can be achieved.

The main parameters used in the selection of inductors are inductance value, rated current, AC resistance, DC resistance, etc., and among these parameters are the concepts specific to power inductors. For example, there are two types of rated currents for power inductors, what is the difference between them? To answer such a question, we explain the rated current of the power inductor here.


The rated current of the power inductor has two methods for determining the rated current, "Irms “based on the rated current of self-temperature rise and the rated current “ Isat” based on the rate of change of the inductance value, which are of great significance, respectively. "Irms rated current based on self-temperature rise" is a rated current specification that measures the heat generated by the component, and may cause component damage and component failure when used over this range.

At the same time, the rated current Isat based on the rate of change of the inductance value is a rated current specification that measures the degree of decline in the inductance value, and the IC control may be unstable due to the increase of the ripple current when used over this range.

In addition, the tendency to magnetic saturation (i.e., the tendency to decrease the inductance value) varies depending on the magnetic circuit structure of the inductor. For the open magnetic circuit type, as the DC current increases, the inductance value is relatively flat until the specified current value, but the inductance value decreases sharply at the specified current value. Conversely, as the closed circuit type increases with current, the value of the permeability gradually decreases, so the inductance value decreases slowly.


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