The TAJC336K025RNJ: The 33 µF capacitance at 25 V rated voltage gives 1.5× derating margin on a 12 V rail, which is the standard practice for tantalum capacitors to avoid surge-related failures. The ±10% tolerance keeps the actual capacitance within 29.7 µF to 36.3 µF over the production spread.
900 mOhm ESR and the ripple-current ceiling
The 900 mOhm ESR at 25°C sets the self-heating under ripple current: a 100 kHz switching regulator with 500 mA ripple current dissipates about 225 mW in the capacitor, which raises the internal temperature by roughly 10-15°C above ambient. Budget this rise when operating near the 125°C upper limit.
The TAJ series is a standard molded-tantalum line from KYOCERA AVX, and this case size C (2312 metric) is a common footprint.