Example 8: Filter Choke with iron powder core

This choke with a toroidal core made from iron powder has a rated inductance of 63 µH and a rated current of 10 A according to the datasheet. The designated use is primarily as filter choke in switch mode power supplies.

The inductance of this exemplar is higher than the nominal inductance in the complete range. Only the small-signal measurement method results in an inductance in the magnitude of the supplier rated inductance of approximately 71 µH. The real inductance is up to 2.5 times higher. After the maximum is reached the inductance decreases. In this case the rated current shows only the thermal limit of the choke.

This example shows very clear the differences between datasheet parameter and the real behaviour of the power inductor. The Power Choke Tester DPG10 allows these deviations to be displayed quickly and easily.