The TPS74901 provides low-output noise when a soft-start capacitor is used. When the device reaches the end of the soft-start cycle, the soft-start capacitor serves as a filter for the internal reference. By using a 0.001µF soft-start capacitor, the output noise is reduced by half and is typically 30µV_RMS for a 1.2V output (10Hz to 100kHz). Further increasing C_SS has little effect on noise. Because most of the output noise is generated by the internal reference, the noise is a function of the set output voltage. The RMS noise with a 0.001µF soft-start capacitor is given in Equation 1.

Equation 1.

The low-output noise of the TPS74901 makes the device a good choice for powering transceivers, PLLs, or other noise-sensitive circuitry.