18 µH wirewound for automotive and industrial DC-DC
The Murata LQH43NH180J03L is a ferrite-core wirewound inductor from the LQH43 series, rated 18 µH ±5% at 1 MHz. It carries a 365 mA current rating and a maximum DC resistance of 420 mOhm — the DCR sets the I²R heating floor for the power path, so the 365 mA figure assumes the self-heating stays within the component's thermal budget.
Self-resonant frequency and Q factor
The self-resonant frequency is 17 MHz — above that point the inductor behaves capacitively, so the useful filtering band stops well before 17 MHz. The Q factor is 35 at 1 MHz, which is the test frequency; Q peaks near the SRF and drops off on either side, so for a 1 MHz switching converter the core losses are moderate. Unshielded construction means the magnetic field couples into nearby traces and components. In a dense layout, keep the inductor away from sensitive analog loops or add a ground ring around the footprint to contain the fringe field.
The surface-mount pads follow the standard 1812 land pattern — the copper pad area under the component sets the heat dissipation path, so the 365 mA rating assumes the board's copper pours carry the heat away. Cut Tape works for prototype builds and rework bench stock.