Drum core wirewound inductor for DC-DC filtering
The Murata LQH43MN390K03L is a 39 µH drum core wirewound inductor in the LQH43 series, unshielded, with a ferrite core. The 240 mA current rating and 1.4 Ohm max DCR define its DC bias capability — at full rated current the self-heating from the DCR is about 81 mW, well within the 85°C ambient limit for most power rail filters.
What the 11 MHz self-resonant frequency means for your filter
The self-resonant frequency of 11 MHz sets the upper bound for effective inductive impedance — above this frequency the inductor behaves capacitively. For a buck converter switching at 500 kHz to 2 MHz, the 39 µH value provides adequate ripple attenuation while staying well below the SRF, so the inductor's impedance remains inductive across the switching harmonic band. The Q factor of 35 at 1 MHz indicates moderate energy storage efficiency at that test frequency. In a resonant tank or tuned filter, the 1.4 Ohm DCR contributes to the overall circuit Q; for a simple power rail filter, the DCR matters more for DC voltage drop than for AC losses.