3 A switch current in a 2 mm × 2 mm WSON
The Texas Instruments TPS61021ADSGR is a synchronous step-up (boost) converter that integrates a 3 A switch in an 8-WSON (2x2 mm) package. That switch current rating is the key spec — it determines how much output current you can deliver at a given input-to-output voltage step. For a 3.3 V rail from a single Li-ion cell (3.0–4.2 V), the 3 A switch supports output loads well above 1 A; from a lower input like 1.8 V, the available output current drops proportionally with the duty cycle. The 2 MHz fixed switching frequency keeps the inductor small — typically 1 µH to 2.2 µH in the 1–2 A output range — and pushes the output ripple above the 20 kHz audio band. The adjustable output range covers 1.8 V to 4 V (max), so it can generate common system rails: 1.8 V, 2.5 V, 3.3 V, or 3.6 V with a resistor divider.
Input range and operating conditions
The input voltage range runs from 0.5 V (minimum) up to 4.4 V (maximum). The 0.5 V minimum allows operation from a deeply-discharged single-cell alkaline or NiMH battery; the 4.4 V ceiling covers a Li-ion cell at full charge.