Inductance, current, and DCR — the three numbers that decide fit
The LQH43NH122J03L is a drum-core wirewound inductor from Murata's LQH43 series, packaged in a 1812 (4532 metric) surface-mount footprint. Its 1.2 mH inductance at 1 kHz test frequency and 40 mA current rating set the operating envelope for DC-DC filter or low-current choke applications. The 24.36 Ohm maximum DC resistance (DCR) is the main thermal constraint — at 40 mA the I²R loss is roughly 39 mW, which is manageable in the 1812 body but means this part is not intended for high-efficiency power paths where DCR below 1 Ohm is typical.
Rated AEC-Q200, this inductor is qualified for automotive stress tests — thermal shock, moisture resistance, and vibration per the passive-component qualification standard. The ferrite core and unshielded construction mean the inductor radiates a magnetic field — keep sensitive traces or other magnetics at least one body width away in the layout.
Q factor and self-resonant frequency — signal integrity limits
The self-resonant frequency is 1.8 MHz; above that the inductor behaves capacitively. Tolerance is ±5%, tighter than the ±10% or ±20% common for power inductors, which matters for resonant circuits or filter poles where inductance accuracy affects the corner frequency.
Supplied in tape-and-reel packaging (cut tape also available), compatible with standard pick-and-place assembly. The base product number LQH43NH covers the full inductance range in this series.