680 µF bulk tantalum — 2.5 V rail, 100 mOhm ESR
The TPSY687K002R0100: The 100 mOhm ESR (Equivalent Series Resistance) governs the ripple current rating — at this impedance, the part can handle a few hundred mA RMS ripple without exceeding the self-heating limit, making it suitable for output filtering on a 2.5 V switching regulator or bulk decoupling on a low-voltage ASIC rail.
