22 µH shielded drum-core for DC-DC and power-line filtering
The Murata LQH43PB220M26L is a 22 µH shielded wirewound inductor in the 1812 (4532 Metric) footprint. It sits in the LQH43 series, a family of ferrite-core drum coils designed for surface-mount power applications where radiated EMI from the magnetic field must stay contained.
Current ceiling and DC resistance: the thermal budget drivers
Rated at 400 mA continuous, this inductor carries the DC bias current that a buck converter or EMI filter leg draws in steady state. The 392.4 mOhm maximum DCR sets the I²R copper loss — at full rated current the winding dissipates roughly 63 mW, which is manageable inside a standard 1812 footprint on a two-layer board with moderate copper pour. The saturation current of 700 mA is the hard ceiling where inductance drops by the test-condition amount. A transient spike or inrush current above 400 mA but below 700 mA is tolerable; sustained operation above 400 mA risks core saturation and loss of filtering effectiveness. Self-resonant frequency is 15 MHz. Above this frequency the inductor's parasitic capacitance dominates and the component behaves capacitively. For a 500 kHz to 2 MHz switching regulator, this part stays well below SRF and maintains inductive impedance across the fundamental and first few harmonics.
Temperature range and deployment context
The ferrite core material retains its magnetic properties across this range; the DCR will increase with temperature per copper's positive temperature coefficient, so the thermal rise at 85°C ambient is higher than at 25°C for the same current. The shielded construction means the magnetic flux is largely contained within the ferrite shell. Adjacent traces carrying sensitive analog signals or high-impedance nodes see less coupled noise than they would from an unshielded drum core of the same inductance and current rating.