The device internal charge pump generates a minimal amount of noise, as shown in Figure 8-1.

Using a bias rail minimizes the internal charge pump noise when the internal voltage is clamped, thereby reducing the overall output noise floor.

The high-frequency components of the output voltage noise density curve are filtered out in most applications by using 10-nF to 100-nF bypass capacitors close to the load. Using a ferrite bead between the LDO output and the load input capacitors forms a pi-filter, further reducing the high-frequency noise contribution.

Figure 8-1 Charge Pump Noise