Inductor Current Rating

ANP019

Coils are used in switching controllers as power coils. Parameters such as inductance, rated, saturated current and RDC, are determined and declared by the coil manufacturers in the datasheet specifications. In practice, coils of identical construction are compared in order to make a selection for a switching controller. But then the question arises for the developer, why the rated current can differ between coils of the same construction from different manufacturers.

Summary

The investigation of the rated current by measurement reveals that the rated current is dependent on external influences during the measurement. High heat removal can falsify the measurement result and lead to inexplicably high rated currents. If coils from Würth Elektronik eiSos are compared with other coils, attention should be placed on the package design and where RDC is identical. Assumption is that the rated current is determined at the same self-heating. If the package design and RDC are the same, the rated current of both coils is the same.

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