SLLSFW6 March 2024 ISOUSB211-Q1
ADVANCE INFORMATION
Figure 8-1 shows an application for isolating a host or a hub using ISOUSB211-Q1. In this example, on the microntroller side, V3P3V1 and VBUS1 are together connected to an external 3.3-V supply. The V1P8V1 supply is generated using the internal 1.8-V LDO by providing 3.3-V supply to VCC1. On the connector side, the VBUS from the USB connector is connected to VBUS2 and the V3P3V2 supply is generated using the internal 3.3-V LDO. VCC2 and V1P8V2 are together connected to an external 1.8-V supply derived from VBUS. Please refer to Thermal ConsiderationsThermal ConsiderationsVBUS / V3P3V PowerVCCx / V1P8Vx PowerExample Configuration 1Example Configuration 2Example Configuration 3Example Configuration 3 for options on optimizing power dissipation inside ISOUSB211-Q1 as required.
Decoupling capacitors are placed next to ISOUSB211-Q1 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 tranisent currents.
ESD diodes with low capacitance and low dynamic resistance, such as PESD5V0C1USF, may be placed on D+ and D- lines. A ferrite bead, with dc resistance less than 100 mΩ, may be optionally placed between VBUS pin of the connector and the VBUS pin of ISOUSB211-Q1, as shown in the figure, to suppress transients such as ESD.
If the isolated power supply used is capable of providing >1.5 A current on the VBUS, the port can be configured as a CDP port according to Battery Charger specification BC 1.2. To do this, the CDPENZ2 pin of ISOUSB211-Q1 must be connected to ground as shown. Under this condition ISOUSB211-Q1 responds to BC 1.2 signaling from a connected peripheral indicating to the peripheral that the port is capable of supply 1.5-A current on VBUS.