What the 300 mOhm ESR means on your power rail
The TPSC156K025R0300: This is a 15 µF tantalum capacitor rated at 25 V with a 300 mOhm equivalent series resistance — the ESR figure that governs ripple current handling and self-heating in a bulk decoupling or filtering role. At 300 mOhm, the capacitor can handle moderate ripple without excessive temperature rise; it is a general-purpose grade, not a low-ESR type for high-frequency switching regulators.
