Input range and what it powers
The TPS61252DSGT: This is a boost converter with a 2.3 V to 6 V input range — it pulls a single-cell Li-Ion battery down to near its depletion voltage, or runs from two alkaline cells. The output side steps that up to a regulated rail for the downstream load. The listed applications — PDAs, portable audio/video, smartphones — tell you this part was designed for handheld gear where the battery voltage sags under load and the converter has to keep the rail steady.
The 8-WFDFN exposed pad (8-WSON 2x2 mm) is a small footprint with a thermal pad underneath.