What the 125 mOhm ESR means for your rail
The TPSE226K035R0125 is a 22 µF molded tantalum capacitor from the TPS series, rated at 35 V with a 125 mOhm equivalent series resistance. That ESR figure is the one that governs ripple handling in a DC-DC output filter — at 500 kHz, a 125 mOhm ESR contributes about 80 mV of ripple per amp of ripple current, which is low enough for most POL regulators but not for a noise-sensitive analog rail where you'd reach for a polymer or a lower-ESR tantalum.
Active production — no last-time-buy scramble
KYOCERA AVX lists this part as Active.
Footprint and temperature grade
It operates from -55 °C to 125 °C, so it survives the thermal cycling in an engine bay or an outdoor base station without derating down to a lower voltage at the high end — the 35 V rating holds across the full range.