Bulk capacitance in a low-voltage, low-ESR footprint
The KYOCERA AVX TPSD687M002R0035 is a molded tantalum capacitor delivering 680 µF at a rated voltage of 2.5 V in the standard 2917 (7343 Metric) D case. The 35 mOhm ESR is the figure that governs ripple current handling and self-heating — for a 2.5 V rail, the derating margin is tight, so the ESR directly sets the AC ripple the part can absorb before internal temperature rise shifts the leakage and accelerates wear-out.
Temperature range and the 35 mOhm ESR trade-off
The 35 mOhm ESR at 25°C increases with temperature — at 125°C the ESR roughly doubles, so the ripple current rating must be derated accordingly. For a 680 µF part on a 1.8 V or 2.5 V core rail, the low ESR keeps the voltage ripple under a few millivolts at moderate switching frequencies, but the self-heating from the ripple current adds to the ambient temperature and must stay within the 125°C ceiling.