What This Boost Converter Does
The TPS61091RSAR is a fixed-output step-up (boost) converter from Texas Instruments, delivering a regulated 3.3V from an input range of 1.8V to 5.5V. It integrates a 2A switch, making it suitable for battery-powered or multi-rail systems that need a clean 3.3V rail from a lower-voltage source like a single Li-ion cell or two alkaline cells. Switching at 600kHz, it uses a synchronous rectifier to keep efficiency up in moderate load ranges — the rectifier MOSFET replaces the usual Schottky diode, reducing forward drop losses.
The 2A switch current rating is the peak inductor current the internal FET can handle — it sets the maximum output current you can draw at 3.3V, which depends on the input voltage and inductor value. At a 3.6V input, expect around 1.5A output; at 1.8V input, output current drops to roughly 0.8A. Plan your load budget accordingly. If your system sees sustained ambient above 85°C, you need a different part. Without proper PCB copper area, the junction temperature rises quickly at full load.