2.2 µF, 50 V, B-case molded tantalum — TAJB225K050RNJ
The 4.5 Ohm ESR sets the ripple current ceiling — for a 50 V rail, derate to 20 V (40% margin) to keep the applied voltage below 2/3 of rated in a 125°C ambient. The B case (1411 / 3528 Metric) footprint is 3.50 mm x 2.80 mm with a seated height of 2.10 mm. Surface-mount termination suits standard reflow profiles.
The 125°C ceiling includes self-heating from ripple current — the 4.5 Ohm ESR means the I²R loss adds to the ambient, so the actual ripple current must be budgeted against the thermal derating curve.