What the 400 mA rating means for your rail
The TPS62222DDCT is a 400 mA step-down (buck) converter with a fixed 1.8 V output — no external feedback divider needed. The 400 mA continuous output sets the load budget for a 1.8 V rail powering an MCU I/O bank, a small FPGA core, or a sensor front-end.
Input range and switching frequency — what they let you do
The 2.5 V to 6 V input range covers 3.3 V and 5 V rails as well as single-cell Li-ion (3.0–4.2 V). The 1.25 MHz switching frequency lets you use a 2.2 µH to 4.7 µH inductor and 10 µF output capacitor, keeping the total solution area under 30 mm². At 1.25 MHz the switching losses are low enough that the part stays cool in the TSOT-23-5 package without a heatsink.
Temperature grade and package — where it survives
The TSOT-23-5 package is a standard 5-pin SOT-23 footprint — no special stencil or reflow profile beyond the usual MSL1 handling.
Sourcing posture
Active lifecycle means the TPS62222DDCT is a standard catalog item from Texas Instruments, available through normal distribution.