1 kOhm impedance at 100 MHz — the suppression target
The BLM15HD102SN1D delivers 1 kOhms of impedance at 100 MHz, which is the sweet spot for attenuating conducted EMI in the 30–300 MHz range — common switching noise from DC-DC converters, clock harmonics, and digital bus radiation. Rated for 250 mA continuous DC current, with a maximum DC resistance of 1.25 Ohms. At full rated current the resistive drop is 312 mV and the self-heating is about 78 mW — well within the 0402 body's dissipation capability at 85 °C ambient.
0402 footprint — board-fit note
Single-line ferrite bead — one signal trace per component, no shared return path.