270 µH wirewound, 100 mA rated — the DCR and SRF set the usable band
The LQH43MN271J03L is a drum-core, wirewound inductor from Murata's LQH43 series, offering 270 µH inductance with ±5% tolerance in a standard 1812 (4532 Metric) surface-mount package.
Unshielded construction — the 4 MHz SRF defines the useful frequency window
The unshielded ferrite core means magnetic flux radiates into the surrounding board area — adjacent traces carrying sensitive analog signals or high-speed edges need keep-out clearance to avoid coupling. Self-resonant frequency is 4 MHz; above this the inductor behaves capacitively and the impedance drops. Practical filtering or energy-storage applications should stay well below that corner — typically below 1–2 MHz for a clean inductive response. Q factor is 40 at 796 kHz, indicating moderate efficiency at that test frequency — the core losses and DCR dominate the loss budget.