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 degrees C, at 500 kHz 50 degree sC and at 1 MHz even lower. The contribution of eddy current Loss to the te mperature 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 tem perature dependent at 1 MHz. The frequency where the residual loss starts t o increase was in good agreement with the onset frequency of dissipation of the complex permeability.