Parametric fit for a 390 µH line
This Murata LQH43NN391K03L is a drum core, wirewound inductor offering 390 µH inductance with ±10% tolerance. The 90 mA current rating sets the DC bias ceiling — above that the inductance rolls off as the core approaches saturation, so budget derating for ripple current in a buck converter or inrush in a filter stage. Maximum DC resistance is 9.7 Ohm, which at 90 mA dissipates about 78 mW — fine for a standard 1812 footprint but worth checking against the board's thermal budget if the inductor sits near a hot component or in a high-ambient enclosure. The self-resonant frequency is 3.3 MHz, and Q is 40 at 796 kHz, so this part is best suited for low-frequency filtering or energy storage below 1 MHz where the Q factor matters for efficiency.
Board-level integration and environment
The unshielded construction means magnetic flux radiates — keep sensitive traces or low-level analog circuits at least a few millimeters away to avoid coupling. The ferrite core material maintains inductance stability across this band, but DCR increases with temperature — expect about 10% rise at 85°C ambient.
Supply and lifecycle posture
The 1812 footprint is widely second-sourced across Murata's LQH43 family and other manufacturers, so qualifying an alternate for dual-source risk mitigation is straightforward.