Buck-boost regulator for single-cell Li-ion to 3.3V rails
The TPS630250YFFR is a synchronous buck-boost regulator from Texas Instruments that handles input voltages from 2.3V to 5.5V and delivers an adjustable output up to 3.6V at 2A or 4A continuous. The 2.5MHz switching frequency keeps the inductor small, but the trade-off is switching losses that eat into efficiency above 85°C ambient. If you are running a 3.3V rail from a Li-ion cell that dips to 2.8V, this part holds the output without dropping into dropout — that is the whole point of a buck-boost topology.
Output current and thermal budget at 85°C
Above 70°C the junction temperature rise from the 20-DSBGA package will force derating — the datasheet's efficiency curves at 2.5MHz show the inflection point. For a 3.3V rail pulling 3A continuous at 85°C, budget a copper pour on the top layer under the DSBGA to pull heat into the board.
Package and layout constraints
The 20-ball DSBGA is a wafer-level chip-scale package.