3.3 µH shielded wirewound for DC-DC filtering
The Murata LQH32PN3R3NNCL is a 3.3 µH drum-core wirewound inductor in the LQH32 series, shielded to contain magnetic flux and rated for 1.55 A continuous current with a saturation current of 1.9 A. The 120 mOhm maximum DCR sets the I²R loss at full load to about 290 mW, which is well within the 85°C ambient rating for most board-level power stages.
Current and saturation margin
The 1.55 A current rating applies to the DC bias before the inductance drops by a specified amount; the 1.9 A saturation current (Isat) is the hard knee where the ferrite core saturates and inductance collapses. A 3.3 V rail drawing 1.2 A leaves 0.35 A headroom below the rating and 0.7 A below saturation — sufficient margin for transient peaks in a buck converter output filter.
Frequency ceiling and self-resonance
The self-resonant frequency of 50 MHz sets the upper limit for effective filtering; above this frequency the inductor behaves capacitively, so it is best suited for switching converters operating below 10 MHz. Inductance is tested at 1 MHz, which is typical for power inductors and confirms the value holds in the low-MHz switching range common to DC-DC converters.