Figure 8-1 shows an application for isolating a host or a hub using ISOUSB111. In this example, on the microcontrollers side, V_3P3V1 and V_BUS1 are together connected to an external 3.3-V supply. On the connector side, the VBUS from the USB connector is connected to V_BUS2 and the V_3P3V2 supply is generated using the internal 3.3-V LDO.

Decoupling capacitors are placed next to ISOUSB111 according to the recommendations provided in the Power Supply Recommendations section. An isolated DC-DC converter (such as the SN6505) is to provide power to the VBUS using the 3.3-V local supply. Note that, for a host or hub, the USB standard requires a 120-μF capacitor to be placed on the VBUS so as to be able provide in-rush current when a downstream peripheral is attached. In addition, a 100-nF capacitor is recommended close to the VBUS pin to handle transient currents.

ESD diodes with low capacitance and low dynamic resistance, such as PESD5V0C1USF, can be placed on D+ and D- lines. A ferrite bead, with DC resistance less than 100 mΩ, can be optionally placed between VBUS pin of the connector and the V_BUS pin of ISOUSB111, as shown in the figure, to suppress transients such as ESD.