3.9 µH wirewound in a 1210 footprint
The Murata LQH32NZ3R9K23L is a drum core, wirewound inductor in the LQH32 series, rated 3.9 µH ±10% at 1 MHz test frequency. Its 290 mA current rating with a 1.1 Ohm max DCR suits low-current DC-DC converter output filtering and signal-line decoupling where the DC bias current stays under a quarter amp. The unshielded construction means the magnetic field radiates — keep sensitive traces or adjacent inductors a board-width away in layout.
SRF and impedance profile
Self-resonant frequency is 35 MHz — above that point the inductor behaves capacitively, so the effective inductance rolls off. For a 3.9 µH part this SRF is typical; the usable band for filtering extends to roughly 10-15 MHz before the Q factor drops significantly. Q factor is 20 at 1 MHz, which is moderate for a ferrite-core wirewound; it indicates the ratio of stored energy to loss at that frequency.