The TPS62221DDCT is a fixed-output step-down (buck) converter from Texas Instruments that delivers 400 mA at 1.5 V. Switching at 1.25 MHz, the part uses a synchronous rectifier — no external Schottky diode needed — which keeps the BOM count low and the efficiency curve competitive at moderate loads.
400 mA load budget and thermal derating
The 400 mA output ceiling is the continuous current rating; the actual load the part can deliver at elevated ambient temperature depends on the board copper area under the SOT-23-5 Thin package. Because the output is fixed at 1.5 V, there is no feedback divider on the board — the resistor network is internal, saving two external components and one layout trace. The positive output configuration and single-output topology simplify the power-tree design.