680 nH, 4.4 A — DC-DC input rail inductor for point-of-load converters
The Murata DFE322512F-R68M=P2 is a 680 nH shielded wirewound inductor from the DFE18SBN series, built with a metal-alloy core. It is rated for 4.4 A continuous current with a saturation floor of 6.1 A, meaning the inductance holds within ±20% up to that peak before rolling off — a common spec for the input side of a buck converter where the inductor sees the full switch current. The 26 mOhm maximum DCR translates to about 0.5 W of I²R loss at the rated 4.4 A. In a 1210 (3225 metric) package with a 1.2 mm seated height, that heat has to exit through the PCB copper — a 2-ounce pour under the part keeps the temperature rise under control in a 40°C ambient.
Shielded metal core — saturation behaviour and EMI profile
Metal-alloy cores saturate more softly than ferrite — the inductance rolls off gradually past Isat rather than dropping off a cliff. For a 6.1 A saturation current, a transient load step that peaks at 5 A still leaves useful inductance, unlike a ferrite core that would hit zero inductance at the same point. The shield also cuts radiated EMI, which matters when the inductor sits near a sensitive RF front-end or an ADC input. Above that, the DCR rises with temperature, and the I²R loss compounds — a thermal camera on the prototype board catches whether the part needs airflow or a larger pad.