DC-DC converter output filter fit
The Murata LQH32PB3R3NN0L is a 3.3 µH shielded wirewound inductor from the LQH32 series, built on a ferrite drum core. It carries a 1.2 A continuous current rating with a saturation floor of 1.25 A, so the inductance holds within 10% of nominal right up to the rated current — useful for a buck regulator output where the ripple current peak pushes past the DC average. The 144 mOhm max DCR sets the copper loss at full load to roughly 0.2 W — the 1210 body sheds that as surface heat without a derating curve down to the -40°C end. At the 125°C ceiling the core loss starts to dominate, but the ferrite material keeps the Q factor above 20 at the 1 MHz test frequency.
Shielding and self-resonance
Shielded construction means the stray field couples less than 2% of the flux into adjacent traces — a critical detail when the inductor sits next to a sensitive analog front-end or a PLL loop filter on the same board layer. The self-resonant frequency is 50 MHz, well above the 1-3 MHz switching range of most point-of-load converters. Below 10 MHz the impedance is purely inductive; above 10 MHz the parasitic capacitance starts to resonate, so this part is not a good fit for an LC filter above 20 MHz.
Package and rework note
1210 (3225 metric) footprint with a 1.70 mm seated height — the ferrite body is not moisture-sensitive (MSL 1), so no bake-out before reflow. The terminations are tin-plated; the hot-air profile should stay under 260°C peak for 10 seconds to avoid cracking the ferrite drum.
Production status and sourcing
The LQH32 series is a mature catalog line; second-source equivalents from TDK (MLZ series) and Taiyo Yuden (NR series) share the same 1210 footprint and 3.3 µH ±20% tolerance, though the DCR and saturation current differ by about 10%. Sourced through authorized distribution and independent channels against an RFQ. No minimum order quantity restriction — single-reel quantities are confirmed at quote time.