What this boost regulator does for a single-cell rail
The TPS61261DRVR is a fixed 3.3V output boost converter from Texas Instruments, designed to step up a low-voltage input as low as 0.8V to a regulated 3.3V rail at up to 100mA. Its 2.5MHz switching frequency keeps the inductor and output capacitor small — a 1µH inductor and 4.7µF ceramic cap typically fit the bill, which matters when board space is tight. The synchronous rectifier improves efficiency at light loads compared to a diode-based boost, so a battery-powered design sees longer run time between charges.
Minimum input of 0.8V means this part can pull a single alkaline cell down to nearly dead and still hold the 3.3V output — useful for a remote sensor or a Bluetooth beacon running on one AA. Maximum input of 4V sets the ceiling: you cannot feed it from a 5V rail or a two-cell Li-ion stack without a pre-regulator. Output is fixed at 3.3V — no feedback resistor network needed, which saves two components and one potential noise injection point on the layout.
Package and thermal — the 6-WSON footprint
Without that thermal via cluster, the 100mA output derates above 70°C ambient. The 2x2 mm footprint is small enough for wearable or IoT modules, but the 0.5 mm pitch on the WSON pads demands a soldermask-defined pad and a stencil aperture that matches the datasheet recommendation.
ROHS3 compliant.