3.3 µF, 25 V, 1.5 Ohm ESR — the decoupling floor
The TPSB335K025R1500 is a 3.3 µF molded tantalum capacitor rated at 25 V with a 1.5 Ohm ESR, housed in the B case (3528 metric). The 1.5 Ohm ESR sets the impedance floor at the switching frequency — for a 100 kHz buck converter this cap shunts the ripple current with about 1.5 Ohms of effective series resistance, so the ripple voltage on the rail is the product of the ripple current and that ESR. A lower ESR part would reduce the ripple further, but the 1.5 Ohm spec is consistent with standard tantalum performance at this case size.
-55 to 125 °C — full military temperature range
The molded construction keeps the tantalum anode sealed against moisture and thermal cycling — no conformal coat needed for the cap itself.
Active production — no EOL clock ticking
KYOCERA AVX lists the TPSB335K025R1500 as Active. No last-time-buy window is open, and no successor has been announced.