3.9 µH drum-core wirewound for power-line filtering
The Murata LQH43NN3R9M03L is a drum-core wirewound inductor in the LQH43 series, unshielded, with a ferrite core. It delivers 3.9 µH ±20% inductance at 1 MHz test frequency, rated for 500 mA continuous current with a maximum DC resistance of 380 mOhm. The 500 mA current rating and 380 mOhm DCR mean this part suits low-to-moderate current power-supply filtering or decoupling where the voltage drop across the inductor stays under 190 mV at full load. The self-resonant frequency of 41 MHz sets the upper limit for effective filtering — above that the inductor behaves capacitively.
1812 SMD package and rework considerations
The unshielded drum-core construction means the magnetic field extends beyond the body — keep sensitive traces or components at least one package width away to avoid coupling. Pin 1 orientation is marked by a dot on the body — verify polarity if the layout uses the dot for consistent pick-and-place.