The TPS74401 is designed to operate from an input voltage between 1.1 V to 5.5 V, provided the bias rail is at least 1.62 V higher than the input supply. The bias rail and the input supply must both provide adequate headroom and current for the device to operate normally.

Connect a low output impedance power supply directly to the IN pin of the TPS74401. This supply must have at least 1 µF of capacitance near the IN pin for stability. A supply with similar requirements must also be connected directly to the bias rail with a separate 1 µF or larger capacitor.

If the IN pin is tied to the bias pin, a minimum 4.7 µF of capacitance is needed for stability.

To increase the overall PSRR of the solution at higher frequencies, use a pi-filter or ferrite bead before the input capacitor.