SPRUJB3 March 2024 AM67 , AM67A , TDA4AEN-Q1 , TDA4VEN-Q1
VBUS detection is supported by the USB2SS via the USB_VBUS pin, but it is important that this pin not be connected directly to the connector 5V or any other 5V source. Instead, an external circuit must be used to ensure that the recommended operating conditions of the pin are not exceeded. Refer to the device datasheet for requirements and example VBUS-sense circuitry.
The PHY includes session valid and VBUS valid comparators and provides corresponding status signals.
The Controller uses the session valid output from the PHY in device mode. One of the reasons is because the USB specification requires that the DP pull-up (implemented inside the PHY) must be be enabled only after VBUS is turned on by host. This PHY output also in general indicates that a connection is active from host and it can also be used to detect disconnects.
The USB2SS wrapper also includes logic to detect a change on session valid and VBUS valid outputs from PHY.