The TPS74401 belongs to a family of ultra-low dropout regulators that feature soft-start. These regulators use a low current bias input to power all internal control circuitry, allowing the NMOS pass transistor to regulate very low output voltages with low V_IN to V_OUT headroom.

The use of an NMOS-pass FET offers several critical advantages for many applications. Unlike a PMOS topology device, the output capacitor has little affect on loop stability. This architecture allows the TPS74401 to be stable with any capacitor ≥ 2.2μF. Transient response is better than PMOS topologies, particularly for low V_IN applications.

The TPS74401 features a programmable, voltage-controlled soft-start circuit that provides a smooth, monotonic start-up and limits startup inrush currents that can be caused by large capacitive loads. A power-good (PG) output is available to allow supply monitoring and sequencing of other supplies. An enable (EN) pin with hysteresis and de-glitch allows slow-ramping signals to be used for sequencing the device. The low V_IN and V_OUT capability allows for inexpensive, easy-to-design, and efficient linear regulation between the multiple supply voltages often present in processor intensive systems.