10.9 × 10.0 mm shielded power inductor for automotive DC-DC stages
The Murata DFEH10040D-100M=P3 is a 10 µH shielded power inductor in the DFEH10040D series, rated for 5.7 A continuous current with a 7.3 A saturation floor. The 33 mOhm max DCR sets the I²R conduction loss — at full rated current the self-heating is roughly 1.1 W, which the iron powder core and 4.0 mm seated height must dissipate into the board copper.
Last Buy — the procurement window is closing
Murata has flagged the DFEH10040D-100M=P3 as Last Buy. This is the final production run — once the allocated inventory clears, the part enters end-of-life and is no longer manufactured. For a BOM that already carries this order code, the decision is whether to buy the lifetime requirement now or qualify a replacement before the window closes. The Last Buy status applies to this specific inductance-tolerance variant; other values in the same family may still be active.
Current rating, saturation, and the real thermal ceiling
Two current limits govern the usable range: the 5.7 A rated current is the DC current at which the temperature rise reaches the datasheet limit, typically 40 °C above ambient. The 7.3 A saturation current is where the inductance drops by 30 % — beyond this the inductor behaves more like a wire and the ripple current in a buck converter rises sharply. In practice, the thermal limit (5.7 A) binds first in a 85 °C ambient; the saturation limit (7.3 A) only becomes the ceiling in low-duty or pulsed applications where the RMS current stays below 5.7 A but the peak exceeds it. The iron powder core has a soft saturation characteristic — the inductance rolls off gradually rather than collapsing, which gives some margin in transient events.
Board-fit and thermal management
The nonstandard surface-mount package measures 10.90 × 10.00 mm with a 4.00 mm seated height. The footprint is larger than a standard 10×10 mm power inductor — the extra 0.9 mm on the length side accommodates the wider core and thicker winding for the 5.7 A rating. The bottom face has a large solder pad that carries the winding current and conducts heat into the PCB copper. For the 1.1 W dissipation at full load, a 2-ounce copper pour on the top layer under the part, with vias to an inner ground plane, keeps the core temperature within the -40 °C to +155 °C operating range. The ±20 % tolerance is typical for power-grade ferrite and iron-powder inductors — the DC bias characteristic shifts the inductance down by 10-15 % at rated current, so the tolerance and bias derating together mean the effective inductance at load is closer to 7-8 µH.