8.3 Initialization Set Up
The general power-up sequence for the TUSB321 device is as follows:
- System is powered off (device has no VDD). The TUSB321 device is configured internally in UFP mode with Rds on CC pins.
- VDD ramps – POR circuit.
- The TUSB321 device enters unattached mode and determines the voltage level from the PORT pin. This determines the mode in which the TUSB321 device operates (DFP, UFP, DRP).
- The TUSB321 device monitors the CC pins as a DFP and VBUS for attach as a UFP.
- The TUSB321 device enters active mode when attach has been successfully detected.