1 µH, 500 mA in a 1812 drum core
The Murata LQH43MN1R0M03L is a drum-core wirewound inductor in the LQH43 series, delivering 1 µH at 500 mA from a standard 1812 (4532 Metric) footprint. The 200 mOhm max DCR means the DC winding loss at full rated current is 50 mW — that is the heat the part sheds into the pad and via array, not the core. Unshielded construction means the magnetic field is not contained by a ferrite shield — adjacent traces carrying sensitive analog signals or another inductor should be kept at least one body width away to avoid coupling.
Self-resonance and Q factor
Self-resonant frequency is 120 MHz — the inductor behaves inductively up to that point; above it the inter-winding capacitance dominates and the impedance drops. For a DC-DC converter switching at 500 kHz to 2 MHz, the 120 MHz SRF gives plenty of headroom so the inductor stays inductive across the switching harmonics. Q factor is 20 at 1 MHz. This is a moderate Q typical of a power-grade ferrite drum core — adequate for input/output filtering in a buck or boost stage, but not a tuned-circuit inductor. The 20% tolerance on the 1 µH nominal means the actual inductance can range from 0.8 µH to 1.2 µH; the DC bias current does not significantly shift it because the core is not gapped, but saturation onset starts above the 500 mA rating.
Active lifecycle, no second-source on record
It is suitable for ongoing production and new designs. No pin-compatible second-source or direct replacement is listed on the record; the 1812 footprint and the 1 µH / 500 mA / 200 mOhm DCR window are common enough that a parametric search will find alternatives, but the LQH43 series specific pad layout and height profile (2.80 mm seated) should be confirmed against any candidate. The part ships on Tape & Reel (TR) or Cut Tape (CT) — standard for pick-and-place assembly.