1.5 µF, 35 V, 2.5 Ohm ESR — what it means on a rail
The TPSB155M035S2500: This is a molded tantalum capacitor from the KYOCERA AVX TPS series, rated 1.5 µF at 35 V with ±20% tolerance. The 2.5 Ohm ESR is the equivalent series resistance at 100 kHz — it sets the ripple current the part can handle before self-heating becomes a derating factor. For a 35 V rail that sees a 100 mV pk-pk ripple at 100 kHz, the ripple current is about 40 mA RMS; at 2.5 Ohm ESR the internal dissipation is roughly 4 mW, well within the part's thermal budget at 85°C ambient.
No last-time-buy window is in effect, and no successor has been announced.
The molded case provides mechanical protection and moisture resistance consistent with a general-purpose surface-mount tantalum.
Dimensions are 3.50 mm x 2.80 mm with a seated height of 2.10 mm max. The 2.10 mm height is a constraint for low-profile assemblies — confirm the board-to-cover clearance before committing.