There is a 5-V voltage regulator inside the part used to supply external loads, such as digital isolators for the high-side drive signal. The digital outputs of the part use this rail as their supply. No capacitor is required for stability, but transient response will be poor if no external capacitor is provided. If the application uses this rail to supply external circuits, TI recommends to have a capacitor of at least 0.1 μF for improved transient response. A larger capacitor can be used for further transient response improvement. The decoupling capacitor used here should be a low-ESR ceramic type.