390 µH drum core wirewound — the DC resistance trade-off
The LQH43MN391K03L is a 390 µH unshielded drum core wirewound inductor from Murata's LQH43 series, housed in a standard 1812 (4532 metric) surface-mount package.
Self-resonant frequency and unshielded field — fit for low-frequency filtering
With a self-resonant frequency of 3.3 MHz, this inductor behaves inductively up to that point; above it the parasitic capacitance dominates and the impedance rolls off. The unshielded construction means the magnetic field extends beyond the package — keep a keep-out zone around the part when placing near sensitive analog or RF traces, or budget for field coupling into adjacent loops. The Q factor of 40 at 796 kHz gives a reasonable figure of merit for resonant tank or filter applications in the low-MHz range. The ferrite core material supports the inductance density in the 1812 footprint but saturates earlier than an air-core or powdered-iron alternative at the same current — the 90 mA rating already accounts for the core's saturation knee.
Active lifecycle — no end-of-life pressure for new designs
The 1812 footprint is widely used across multiple Murata LQH43 variants and competitive wirewound inductors, so a second-source fallback exists within the same pad layout if supply tightens.