2.2 µF at 50 V — the decoupling or bulk-storage fit
The TAJD225K050HNJ: This is a 2.2 µF molded tantalum rated for 50 V continuous, ±10% tolerance. For a typical 100 kHz switching regulator output, that ESR means the capacitor dissipates about 0.5 W at 400 mA ripple, which is within the 2000-hour endurance at 125 °C.
D case 2917 — footprint and board fit
The D case size (7.30 mm x 4.30 mm, 3.10 mm seated height) is the standard 2917 footprint. The surface-mount pad layout follows the EIA-7343-31 pattern — the same footprint used by most 2917 tantalum capacitors, so swapping in another D-case TAJ part is a straight BOM change.