6.8 µF at 25 V — bulk decoupling for 12 V rails
The TAJB685M025Y is a molded tantalum capacitor from the TAJ series, rated 6.8 µF at 25 V with ±20% tolerance. That capacitance and voltage combination fits 12 V rail bulk decoupling in industrial controls, telecom line cards, and power-supply outputs where a 25 V rating provides the standard 80 % derating margin on a 12 V bus.
2.8 Ohm ESR — the ripple-current ceiling
With an ESR of 2.8 Ohm, the self-heating from AC ripple current is the limiting factor — at 100 kHz, the I²R loss raises the internal temperature above ambient. For a 100 mA ripple component, the dissipation is 28 mW; in still air inside a sealed enclosure that heat accumulates and reduces the capacitor's effective lifetime. Budget the ripple current against the derating curve in the TAJ series datasheet.
B case 1411 — board-fit dimensions
The B case code (1411 / 3528 Metric) measures 3.50 mm x 2.80 mm with a seated height of 2.10 mm max. The 0.50 mm pitch between the anode and cathode pads is standard for this case size — the footprint matches the EIA 3528-21 land pattern. Confirm the pad geometry against your PCB layout; the 2.10 mm height may conflict with a 2.0 mm clearance under a mezzanine board.