68 µH, 180 mA — what the ratings mean for the BOM
The LQH43NN680K03L: At 68 µH with a 180 mA current rating, this inductor handles typical DC-DC converter ripple and low-power filtering in the LQH43 series. The 1.9 Ohm max DCR sets the I²R conduction loss — at full rated current that is about 62 mW dissipated in the winding, which the ferrite core and 1812 body can sink without exceeding the 105 °C operating ceiling. The self-resonant frequency of 8.4 MHz means the inductance holds up to roughly 2-3 MHz in a buck converter before parasitic capacitance starts to roll it off. Below that frequency the unshielded construction radiates a stray field — keep sensitive traces and the feedback loop at least a few mm away on the PCB.
1812 footprint and field-swap fit
Orientation is unambiguous: the part has no polarity marking, so it goes either way. Reflow with a standard profile; no hot-air station needed. The ferrite core material is stable across that band, though DCR will climb about 0.4 % per °C — at 85 °C ambient the winding resistance is roughly 1.9 Ohm x 1.24 = 2.36 Ohm, which still keeps the temperature rise within the part's rating at 180 mA.