330 µH ferrite-core wirewound for filtering and bias-T applications
The Murata LQH32MN331J23L is a 330 µH unshielded wirewound inductor in the LQH32 series, wound on a ferrite drum core and housed in a 1210 (3225 Metric) surface-mount package. Rated for 65 mA DC with a maximum DC resistance of 13 Ω, this part is sized for low-current filtering, decoupling, and bias-T networks where the inductance value matters more than current handling.
Self-resonant frequency and Q factor — where the part stops being an inductor
The self-resonant frequency is 5 MHz; above that the component behaves capacitively and the effective inductance drops off. For a 330 µH value this is a typical SRF — the winding capacitance sets the ceiling. Q factor is 40 at 796 kHz, measured at the test frequency of 1 MHz. This Q is moderate for a wirewound ferrite-core inductor — expect higher core losses than an air-core at the same inductance, but the ferrite keeps the package small.
For a 1210 footprint the ferrite core and unshielded construction are the main constraints on ambient temperature rise.
Unshielded construction — watch the board-level coupling
This is an unshielded drum-core inductor. The magnetic field radiates from the open side of the core — adjacent traces carrying sensitive analog signals or high-impedance nodes should be kept at least one part-width away to avoid parasitic coupling. The ±5% tolerance on 330 µH is tight enough for resonant tank and filter designs that need a predictable L value without trimming.