22 µH, 540 mA — where the ratings matter
The LQH3NPN220MMEL: This is a 22 µH shielded wirewound inductor in Murata's LQH3 series, built on a ferrite core. The 540 mA DC current rating is the continuous limit before self-heating shifts the inductance — stay under it and the part holds its value within the ±20% tolerance band. The saturation current is 570 mA, just 30 mA above the rated current. That tight margin means the inductor saturates almost immediately once you exceed the DC bias limit — inductance drops sharply, and the circuit sees a short instead of a filter. For a buck converter output choke, keep the peak inductor current below 540 mA to stay in the linear region.
480 mOhm DCR and self-resonant ceiling
480 mOhm max DC resistance is the number that sets the I²R copper loss. At 540 mA, that is about 140 mW dissipated in the winding — fine for a 3x3 mm part on a standard PCB with decent copper pour, but worth checking if the inductor sits next to a hot regulator or in a sealed enclosure with limited airflow. The self-resonant frequency is 10 MHz. Above that frequency, the parasitic capacitance between winding layers dominates and the part stops behaving like an inductor. For a 500 kHz to 2 MHz switching regulator — the typical range for a part this size — you have plenty of headroom. Pushing it past 5 MHz starts eating into the margin.
Shielded construction and 1212 footprint
The ferrite shield keeps the magnetic field contained — useful when the inductor sits close to sensitive analog traces or a wireless front-end. The 1212 (3030 Metric) case measures 3.00 mm per side with a 1.50 mm seated height, so it fits the common 3x3 mm power inductor land pattern used across many DC-DC converter reference designs. Surface-mount package, supplied on tape and reel or cut tape.