Unshielded drum core — the field leaks
The LQH43NN121K03L is a drum-core wirewound inductor with a ferrite core and no magnetic shield — the stray field couples into adjacent PCB traces, so a keep-out zone under and around the part is needed on the layout. Inductance is 120 µH measured at 1 MHz, with a self-resonant frequency of 6.2 MHz — above that frequency the parasitic capacitance turns the inductor capacitive, so the part is only useful as an inductor below 6.2 MHz.
Q factor and where it peaks
Q factor is 40 at 796 kHz — this is the frequency where the inductor's energy storage efficiency peaks; at the self-resonant frequency the Q drops to near-zero as the parasitic capacitance takes over. The 150 mA current rating is the DC bias current at which the inductance typically drops 10 % — the saturation current is higher but not separately quoted in the datasheet; the part derates above 85 °C ambient.