2.2 µF, 6.3 V, 20 Ohm ESR — the ESR is the limiting factor for ripple handling
The TAJR225K006SNJ: This is a 2.2 µF molded tantalum capacitor from the TAJ series, rated at 6.3 V with ±10% tolerance. The 20 Ohm ESR is the spec that matters most for power rail decoupling — at switching frequencies above a few hundred kHz, the impedance is dominated by the ESR, not the capacitance. A 100 kHz ripple current of 50 mA pk-pk dissipates 50 mW in the ESR, which raises the internal temperature and accelerates aging. For a 6.3 V rail, the derating rule of thumb (50% margin) means the applied voltage should stay below 4.2 V to avoid surge failures.
At the cold end, the capacitance shifts by about -10% from the 25°C value; at 125°C, the leakage current rises and the ESR increases by roughly 1.5×. The 0805 case size (2.05 mm x 1.30 mm) limits the heat dissipation — the part should not be placed next to a high-power inductor or regulator without thermal analysis.
The part is in production and suitable for new designs.