Why the 125°C rating matters for your board
The TPSA154K050R9000: That range means it can sit next to a hot power stage or inside an outdoor enclosure that sees direct sun without derating the capacitance or risking catastrophic failure. A commercial-grade tantalum limited to 85°C would need a cooler spot or a larger case to spread the heat.
9 Ohm ESR — the thermal budget driver
At 9 Ohm ESR, this 0.15 µF capacitor dissipates I²R heat from ripple current. For a 50 V rail with a 100 mA ripple, the self-heating is under 0.1°C — negligible. But if the ripple current reaches 500 mA, the internal temperature rise approaches 2.3°C, eating into the 125°C ceiling. The ESR also sets the impedance floor at high frequency; a 9 Ohm ESR at 100 kHz gives a total impedance of about 9.1 Ohm, dominated by the resistive term.
Active lifecycle — no sourcing surprises
The product status is Active, meaning KYOCERA AVX continues to manufacture this part.
1206 case — layout and footprint fit
The 1206 (3216 Metric) case measures 3.20 mm x 1.60 mm with a seated height of 1.80 mm max.