Temperature dependence of power loss of Mn-Zn ferrites at high frequency

The power loss characteristics of Mn-Zn ferrites were observed up to 1 MHz at 25 mT as a function of temperature. At 100 kHz the temperature at which the power loss minimum occurred was near 70/spl deg/C, at 500 kHz 50/spl deg/C and at 1 MHz even lower. The contribution of eddy current loss to the temperature dependence of the total power loss was negligibly small at 1 MHz because the resistivity is independent of temperature. The contribution of the residual loss due to magnetic rotation was significant and strongly temperature dependent at 1 MHz. The frequency where the residual loss starts to increase was in good agreement with the onset frequency of dissipation of the complex permeability.