5 Implementation with actual components

Figure 5-1 shows the implementation of a self-powered isolated USB Type-C port with actual components. These include the Texas Instruments ISOUSB211 isolated USB repeater, SN6505 5-W push-pull transformer driver, TUSB320LAI USB Type-C controller, ISO7710 digital isolator, TPS25910 VBUS switch and ISO1640 isolated I2C isolator. The ISOUSB211 supports automatic role detection, with both side 1 and side 2 capable of assuming upstream- and downstream-facing roles based on which side detects a 1.5-kΩ pullup first. This feature is necessary for dual-role implementations.

The ID output of the TUSB320LAI indicates the negotiated role of the port. This ID information can control the power switch, and is also conveyed across the barrier to the controller using the ISO7710 digital isolator.

It is possible to provide the VBUSOK1 output of the ISOUSB211 as input to the VBUS detect pin of the controller. When acting as a peripheral or upstream-facing port, this pin lets the controller know when VBUS becomes available on the connector, after which the controller can proceed to enable its 1.5-kΩ pullup resistor.

The ISO1640 isolated I2C isolator is optional, and allows access to additional configuration options in the TUSB320LAI, such as advertising up to 3-A VBUS current in host mode and configuring the DRP as try.SRC (where the DRP preferentially tries to establish itself as a downstream-facing port when connected to another DRP) or try.SNK (where the DRP preferentially tries to establish itself as an upstream-facing port when connected to another DRP). In the simplest implementations where the DRP only needs to advertise 0.5-A output current, and with no try.SRC or try.SNK features, the ISO1640 device is not necessary.