10 µH at 950 mA — the rail-filtering sweet spot
The DFE252012F-100M=P2 is a 10 µH shielded wirewound inductor rated for 950 mA continuous with a saturation current floor of 1.4 A. That 1.4 A Isat ceiling is the hard limit — once the core saturates, inductance collapses and the ripple current spikes. For a buck converter switching at 1–2 MHz, the 950 mA rated current gives about 20 % headroom above the expected DC load, which keeps the core out of saturation during load transients. The 480 mOhm max DCR is the number that sets the copper loss. At 950 mA, I²R loss is 0.43 W — that heat has to get out of the 1008 package. The iron powder core runs cooler than ferrite at high ripple frequencies, but the copper loss still dominates the temperature rise.
Shielded construction and flat-wire winding
The shielded drum core with flat wire winding is Murata's play for reducing radiated EMI in tight layouts. The flat wire packs more copper cross-section into the same window area compared to round wire, which is why the DCR stays at 480 mOhm despite the 10 µH inductance and 1008 footprint. For a POL converter sitting next to a radio front-end, the shielding keeps the magnetic field from coupling into the receive path. The iron powder core material handles DC bias better than ferrite — inductance roll-off starts at a higher current. That matters when the inductor sees a 1.4 A saturation rating but the DC bias is 800 mA; the effective inductance at load is closer to 9 µH than a ferrite core's 7 µH. The 1 MHz test frequency in the spec is typical for the inductance measurement, not the operating frequency — the part is designed for 1–3 MHz converters.