27 µH wirewound for DC-DC filtering and bias-T circuits
The Murata LQH32MN270J23L is a 27 µH unshielded wirewound inductor in the LQH32 series, built on a ferrite drum core. Rated for 125 mA continuous current with a maximum DC resistance of 3.1 Ohm, this part is sized for low-current power rail filtering, bias-T decoupling, and signal-path chokes where the DC bias current stays under 100 mA to keep resistive losses manageable.
Self-resonant frequency and Q factor set the usable band
The self-resonant frequency (SRF) is 13 MHz. Above this frequency the inductor behaves capacitively, so the part is effective for filtering and impedance matching in circuits operating up to a few MHz, such as low-frequency DC-DC converter output stages or audio-band noise suppression. A Q factor of 35 at 1 MHz indicates moderate energy storage efficiency at that test frequency. The Q peak typically occurs near the SRF, so the part offers its best selectivity in the 1–10 MHz range.
Unshielded construction and PCB placement
This is an unshielded inductor. The open ferrite core radiates a magnetic field that can couple into nearby traces or components. Keep sensitive analog or RF circuitry at least one part-width away, and avoid routing a high-current loop directly under the inductor on the opposite board layer. The nonstandard case designation means the pad layout should follow the manufacturer's recommended land pattern, not a generic 1210 resistor footprint, to ensure solder fillet formation on the terminations. Operating temperature range is -40°C to +85°C, covering commercial and most industrial environments. The inductance tolerance is ±5%, which is tight enough for tuned LC filters where the capacitance tolerance is also held to 5% or better.