What this 220 µF molded tantalum cap is for
The 50 mOhm ESR is the key parametric — it limits the ripple current heating and sets the usable frequency range for bulk decoupling on a 3.3 V or 1.8 V rail. The D case code tells you the body height is 3.10 mm max — check clearance under a neighbouring component or a low-profile enclosure.
It can sit in an engine-bay ECU, a downhole sensor module, or a satellite power bus where the ambient swings from cold-soak to self-heat. Because it is a molded part, the case resists moisture ingress better than a conformally-coated chip — store the reels in a dry cabinet if the ambient humidity is above 60% RH, but the MSL level is typically 3 (168-hour floor life) for this construction.
If you need a functional equivalent, look for a 220 µF, 4 V, 50 mOhm ESR molded tantalum in a 2917 case from Kemet or Vishay — the footprint and ratings are interchangeable, but confirm the case height and ESR tolerance at your operating temperature.