What this part does — source selection for dual-supply rails
The Texas Instruments TPS2111PW is a 2:1 source selector switch that selects between two input power rails. It integrates N-channel FETs internally.
Supply range and output current — sizing the rail
Rated for 2.8V to 5.5V input, the TPS2111PW works with Li-ion battery packs (3.0V–4.2V) as well as regulated 3.3V or 5V buses. The 1.25A maximum output is a continuous rating; if your load peaks above that, you need a higher-current part or a parallel path. At 55 µA supply current, the switch itself won't dominate the system power budget — compare that to the load current, and the overhead is negligible.
Temperature grade and environment
The 8-TSSOP package is surface-mount, so it reflows on a standard profile. No AEC-Q grade is listed, so it's not formally automotive-qualified, but the temperature range itself doesn't rule out benign under-hood use if you run your own qualification.