220 µH wirewound in a 1812 footprint
The Murata LQH43NN221J03L is a drum core wirewound inductor from the LQH43 series, built for general-purpose filtering and decoupling in surface-mount designs. It delivers 220 µH inductance with a ±5% tolerance, rated at 110 mA continuous current.
Parametric fit: Q, SRF, and the 1 MHz test point
A Q factor of 40 at 796 kHz indicates moderate ac losses in the ferrite core at that frequency — adequate for power-line filtering and dc-dc converter input/output stages where the ripple fundamental sits in the hundreds of kHz. The self-resonant frequency of 4.5 MHz defines the upper bound for inductive behaviour; above that the part becomes capacitive. Inductance is tested at 1 MHz, which is above the Q test frequency but still well below SRF — the value quoted is the nominal inductance at that test condition, not a derated figure.
The unshielded construction means stray flux can couple into adjacent traces or components — keep sensitive routing or low-level analog signals at least one part-width away. Supplied on tape and reel (cut tape option available), it is compatible with standard pick-and-place for 1812 footprints. No special bake-out is required for MSL if stored per JEDEC moisture sensitivity guidelines.