Why does saturation current decrease at high operating temperature?
Saturation current decreases at high temperature because the magnetic core’s permeability and magnetic flux density capability degrade as temperature rises, causing the core to reach saturation at a lower current level.
Technical explanation:
Magnetic core materials used in power inductors exhibit temperature-dependent characteristics. As temperature increases, the core’s permeability decreases and the material approaches its magnetic limits more quickly. This reduces the maximum usable magnetic flux density, meaning less current is required to drive the core into saturation.
In ECU DC-DC converters, this effect is particularly critical because power stages often operate continuously in elevated ambient temperatures, combined with self-heating caused by conduction and switching losses.