2.2 mH at 30 mA — where the DC bias ceiling sits
The LQH43NN222K03L is a Murata drum-core wirewound inductor in the LQH43 series, delivering 2.2 mH ±10% inductance in an 1812 (4532 Metric) SMD package. Rated at 30 mA DC, the current rating is the point where the inductance typically drops by 10% due to core saturation — exceeding it collapses the inductance and the filtering stops working. The 50 Ohm maximum DC resistance means at 30 mA the self-heating is roughly 45 mW (I²R), negligible for most boards, but the voltage drop across the inductor at that current is 1.5 V — a factor if the rail margin is tight.
Q factor and self-resonant frequency — where it actually works
Q factor is 40 at 252 kHz — this is the sweet spot for AC loss; above or below that frequency the Q drops and the inductor dissipates more signal energy as heat. Self-resonant frequency is 1.3 MHz — above this the part behaves capacitively, not inductively. Keep the operating frequency below 1.3 MHz to stay in the inductive region. Unshielded construction means the magnetic field radiates freely — place it at least one part-width away from sensitive analog traces or other magnetics to avoid coupling.