The downstream port power, VBUS, must be supplied by a source capable of supplying 5 V and at least 500 mA per port. Downstream port power switches can be controlled by the TUSB4020BI signals. It is possible to leave the downstream port power always enabled.
Each downstream port’s VBUS requires a large bulk low-ESR capacitor of 22 µF or larger to limit in-rush current.
TI recommends ferrite beads on the VBUS pins of the downstream USB port connections for both ESD and EMI reasons. A 0.1-µF capacitor on the USB connector side of the ferrite provides a low-impedance path to ground for fast rise time ESD current that might have coupled onto the VBUS trace from the cable.