400 mA step-down in a SOT-23-5 Thin package
It switches at 1.25 MHz and integrates a synchronous rectifier, so no external Schottky diode is needed — the efficiency curve stays clean across light and full load. The output is fixed at 1.7 V, which suits powering low-voltage digital cores or sensor rails in portable and industrial gear.
TI has discontinued the TPS62229DDCR, so it is no longer available through the factory channel. The SOT-23-5 Thin package (TSOT-23-5) is a surface-mount footprint with 0.95 mm pitch and a low profile — about 1 mm max height. It reflows well with a standard lead-free profile; the small thermal mass means it heats quickly under hot air, so keep the nozzle temperature around 300°C and watch for the part to shift if the airflow is too high.
The 400 mA output current sets the load budget — this converter is sized for low-power rails, not a 1 A+ supply. The 1.25 MHz switching frequency lets you use a small inductor (typically 2.2 µH to 4.7 µH) and low-ESR ceramic output capacitors, keeping the total solution footprint compact. Input voltage range is 2.5 V to 6 V, so it runs from a single Li-ion cell (3.0 V to 4.2 V) or a 3.3 V / 5 V regulated rail. The fixed 1.7 V output is set internally — no feedback resistor divider needed, which saves two components and one PCB trace.