Active automotive-grade power inductor
The Murata LQH43NH120J03L is an active-production wirewound drum-core inductor in the LQH43 series, qualified to AEC-Q200 for automotive applications. It delivers 12 µH ±5% at 420 mA continuous with a maximum DC resistance of 300 mOhm. The 1812 (4532 Metric) surface-mount footprint and -40 to +125 °C operating range suit it for DC-DC converter input/output filtering and power-supply decoupling in engine-control units, body controllers, and infotainment power stages.
What the key ratings mean for the BOM
At 420 mA the I²R loss through the 300 mOhm DCR is about 53 mW — the 1812 body in still air stays within the 125 °C rated limit without forced cooling, but derate current if ambient exceeds 85 °C or the part is packed next to other heat sources. The unshielded drum-core construction means the magnetic field radiates — keep sensitive analog traces, other inductors, or ferrite beads at least one body width away to avoid cross-coupling. With a Q of 35 at 1 MHz and a self-resonant frequency of 21 MHz, the inductor behaves as a pure inductance well above the 1–2 MHz switching frequencies common in automotive DC-DC converters. The SRF is high enough that capacitive coupling does not degrade filtering above the converter's fundamental.
Sourcing and compliance
RoHS compliance is standard for the series.