68 µF bulk decoupling on a 4 V rail
The TAJT686K004RNJ: This is a 68 µF molded tantalum capacitor rated at 4 V with ±10% tolerance — a standard bulk-decoupling value for 3.3 V or 2.5 V power rails where the 1.5 Ohm ESR provides enough damping to avoid ringing with the upstream regulator's output impedance. The 1.5 Ohm ESR is a design parameter: it limits the ripple current the capacitor can handle without self-heating, and it sets the zero in the control-loop compensation of the downstream regulator.
Housed in the 1411 (3528 Metric) case, size code T, the capacitor measures 3.50 mm x 2.80 mm with a seated height of 1.20 mm — a low-profile footprint that fits under a heatsink or on the back side of a dense PCB. Surface-mount, supplied on tape and reel — compatible with standard pick-and-place and reflow profiles for the TAJ series.