Two rails in one QFN — boost plus LDO
The Texas Instruments TPS61100RGERG4 combines a synchronous step-up (boost) converter and a linear LDO regulator in a single package.
Input range and switching — what drives the BOM decision
The supply input accepts 0.8 V to 3.3 V, so this part starts up from a single-cell alkaline or Li-ion battery that has dropped below 1 V. The boost converter switches at 500 kHz, which keeps the inductor small enough for a compact layout but not so fast that the switching losses eat into efficiency at light loads.
Package and rework — what the QFN means at the bench
The package with exposed pad provides a primary heat path for thermal management.