Most low-noise and low-ripple applications use a ferrite bead and bypass capacitor before the load. Using a second L-C filter is especially useful for low-noise and low-ripple applications with constant load current such as ADCs, DACs, and Jitter Cleaner. The second stage L-C filter is optional, and the device can be used without this filter. Without the filter, the device has a low output voltage noise of typically 16.6 μV_RMS shown in Figure 6-29 with an output voltage ripple of 280 μV_RMS shown in Figure 6-10. The second stage L-C filter attenuates the output voltage ripple by another approximately 30 dB shown in Figure 6-12. To improve load regulation, the device can remote sense the output voltage after the second stage L-C filter and is internally compensated for the additional double pole generated by the L-C filter.

To keep the second stage L-C filter as small as possible, the internal compensation is optimized for a 10-nH to 50-nH inductance. A small ferrite bead or even a PCB trace provides sufficient inductance for output voltage ripple filtering. See Section 8.2.2.2.3 for details.