SLVSD02E March 2015 – August 2021 TPS65982
The USB low-speed Endpoint is a USB 2.0 low-speed (1.5 Mbps) interface used to support HID class based accesses. The TPS65982 supports control of endpoint EP0. This endpoint enumerates to a USB 2.0 bus to provide USB-Billboard information to a host system as defined in the USB Type-C standard. EP0 is used for advertising the Billboard Class. When a host is connected to a device that provides Alternate Modes which cannot be supported by the host, the Billboard class allows a means for the host to report back to the user without any silent failures.
Figure 9-38 shows the USB Endpoint physical layer. The physical layer consists of the analog transceiver, the Serial Interface Engine, and the Endpoint FIFOs and supports low speed operation.
The transceiver is made up of a fully differential output driver, a differential to single-ended receive buffer and two single-ended receive buffers on the D+/D– independently. The output driver drives the D+/D– of the selected output of the Port Multiplexer. The signals pass through the 2nd Stage Port Data Multiplexer to the port pins. When driving, the signal is driven through a source resistance RS_EP. RS_EP is shown as a single resistor in USB Endpoint Phy but this resistance also includes the resistance of the 2nd Stage Port Data Multiplexer defined in Port Data Multiplexer Requirements and Characteristics. RPU_EP is disconnected during transmit mode of the transceiver.
When the endpoint is in receive mode, the resistance RPU_EP is connected to the D– pin of the top or bottom port (C_USB_TN or C_USB_BN) depending on the detected orientation of the cable. The RPU_EP resistance advertises low speed mode only.