This combination is a typical choice for bulk decoupling on 3.3 V or 2.5 V supply rails, where the 4 V rating provides about 20% derating margin — standard practice for tantalum capacitors to avoid inrush stress.
350 mOhm ESR – ripple current and thermal budget
With a maximum ESR of 350 mOhm, this capacitor handles ripple current without excessive self-heating. In a typical buck converter output filter, the ESR sets the output voltage ripple amplitude — lower ESR means less ripple at the same ripple current, but also reduces the damping of the LC resonance. The 350 mOhm figure is moderate, suitable for general-purpose filtering where a balance between ripple and stability is needed.