1.8 mH at 35 mA — what the ratings mean for your filter or supply
The LQH43NH182J03L is a ferrite-core drum wirewound inductor from Murata's LQH43 series, delivering 1.8 mH ±5% inductance in a standard 1812 SMD package. At 35 mA continuous rated current, the 32.04 Ohm max DCR produces a 39 mW I²R loss — the part runs cool at its rated load, but the DCR does limit efficiency in higher-current paths. AEC-Q200 qualification means this inductor passed automotive-grade stress tests: thermal shock, vibration, solder heat resistance, and moisture resistance. That makes it suitable for under-hood or chassis-mounted electronics where temperature swings and mechanical shock are the norm, not just benign indoor gear. The self-resonant frequency sits at 1.5 MHz — above that the part behaves capacitively and stops being an inductor. For a buck converter switching at 500 kHz, the 1.5 MHz SRF gives enough margin; for a 2 MHz switcher, you'd want a part with a higher SRF. The Q factor of 40 at 252 kHz tells you the core losses are low in the low-frequency filter band, which is where this value of inductance is typically applied.
Rework and board-fit — what the 1812 package needs
That's a standard two-terminal footprint with wide pads — easy to hand-solder or rework with hot air. The ferrite drum core is mechanically robust; it won't crack under a moderate reflow profile. Pin 1 is the terminal on the marked end, clearly indicated by the orientation mark on the body. The part is unshielded, so keep it away from sensitive analog traces or adjacent magnetics that might couple noise. In a rework scenario, the ferrite core absorbs moisture slowly — no special bake needed unless the reel has been sitting in high humidity for weeks. Standard 260°C peak reflow profile works fine.