The TS2431AILT is an adjustable shunt voltage reference from STMicroelectronics, in a three-pin SOT-23-3 package. It's the kind of part you find setting the feedback node in a linear regulator or limiting the voltage on a supervisory input. The output is adjustable from 2.5 V up to 24 V, with a ±1% tolerance that's tight enough for most general-purpose power and monitoring circuits. The 100 mA output current and 1 mA cathode current mean it can sink enough current to regulate a small rail or pull down a comparator input without extra buffer stages.
The 100 ppm/°C temperature coefficient is typical for a ±1% shunt reference; if your design needs tighter drift over temperature, you'd step up to a ±0.5% or ±0.25% grade like the TL1431ACL5T, but that part's temperature range tops out at 70°C.
If you're populating a BOM for a new build, this part carries no end-of-life flag.