Inductance and current rating for filter and bias circuits
The LQH32MN180J23L is a drum core wirewound inductor from Murata's LQH32 series, offering 18 µH inductance with ±5% tolerance. The 165 mA current rating defines the DC bias limit — exceeding this saturates the core and collapses the inductance, so the steady-state load plus ripple current must stay below this figure. Maximum DC resistance is 2.5 Ohm, which at 165 mA produces a copper loss of about 68 mW.
Self-resonant frequency and Q factor
Self-resonant frequency is 15 MHz. Above this point the inductor's parasitic capacitance dominates and the impedance becomes capacitive — the part is usable as an inductor only well below 15 MHz, typically up to a few MHz for power filtering or signal decoupling. Q factor is 35 at 1 MHz, indicating moderate energy storage efficiency at that test frequency. For applications requiring higher Q (tuned circuits, narrowband filters), a different core material or construction may be needed.
Package and board integration
The unshielded construction means magnetic flux couples to nearby traces and components — keep sensitive analog or RF circuits at least a few mm away, or use a shielded inductor if coupling is a concern.