The TUSB320 device can be configured as an UFP only by pulling the PORT pin low to GND. In UFP mode, the TUSB320 device constantly presents pulldown resistors (Rd) on both CC pins. The TUSB320 device monitors the CC pins for the voltage level corresponding to the Type-C mode current advertisement by the connected DFP. The TUSB320 device debounces the CC pins and wait for V_BUS detection before successfully attaching. As an UFP, the TUSB320 device detects and communicates the advertised current level of the DFP to the system through the OUT1 and OUT2 GPIOs (if in GPIO mode) or through the I²C CURRENT_MODE_DETECT register one time in the Attached.SNK state.

After initial connection, the advertised current by the connected DFP could change due to changes in its system power resource. For example, a DFP could advertise high current on initial connection but then decide to reduce to default current because user removed external power adapter from their notebook. Because the TUSB320 will only advertise on OUT1 and OUT2 the initial advertised current, it is recommend to monitor the advertised current through the TUSB320’s I2C interface from the CURRENT_MODE_DETECT register. System software must periodically perform a I2C_SOFT_RESET in order for the CURRENT_MODE_DETECT register to be updated based on the state of the CC pins.