Fixed 4.5V boost with 2.4A switch in a 9-bump DSBGA
The TPS61254YFFT is a fixed-output step-up (boost) converter from Texas Instruments that delivers a regulated 4.5V rail from a 2.5V to 4.35V input source. Its internal switch is rated for 2.4A, which sets the practical load ceiling — at 4.5V out, that switch current translates to roughly 1.5A to 1.8A output depending on efficiency and input voltage. The 3.5MHz switching frequency lets you use a small inductor (typically 1 µH to 2.2 µH) and small ceramic caps, keeping the total solution area tight. The output is fixed at 4.5V, which is a common rail for USB On-The-Go, Li-ion boost to 5V-ish logic, or powering a small sensor node from a single-cell battery.
Package and thermal reality for a 9-DSBGA
The 9-bump DSBGA (0.4mm pitch typical) is a wafer-level package with no mould compound — the die is the package. That means the board footprint is tiny (under 2 mm²), but the thermal path is through the solder bumps to the PCB copper. For a boost converter switching 2.4A, the copper area under the device and the number of via drops to the inner layers directly set the junction temperature. At 85°C ambient and full load, the thermal budget is tight; a 2-layer board with minimal copper may force derating.
ROHS3 compliant.