SLLSEW6C November 2016 – June 2018 TUSB422
PRODUCTION DATA.
Refer to the PDF data sheet for device specific package drawings
VCONN is required by active cables, emarker, and VCONN powered accessories like Alt Mode adapters. These types of devices or cables present Ra on one CC pin and Rd on the other CC pin. VCONN must be enabled when any of device or cable requiring VCONN is connected to a Type-C port and the TUSB422 is operating as a DFP or DFP in DRP mode. Software can also enable the VCONN switch when the TUSB422 is a UFP during a VCONN_SWAP sequence. The TUSB422 implements a VCONN switch which is controlled by software. The default state of this switch is open. By setting the ENABLE_VCONN bit in Power Control register, the TUSB422 removes closes the switch resulting in VCONN power to be connected to the CC pin indicated by value of PLUG_ORIENTATION bit in TCPC Control register.
Once the VCONN switch is closed, the switch can be opened by any of the following conditions.
The TUSB422 discharges VCONN to vSafe0V by enabling Rd at designated CC pin anytime the VCONN switch transitions from closed to open state. Once at vSafe0V, the TUSB422 disables the discharge circuit by removing Rd and then re-enable Rp (assuming it is still enabled in Role Control register).
If an external VCONN discharge is desired, the TUSB422 internal VCONN discharge circuit can be disabled by setting the INT_VCONNDIS_DISABLE bit in the VBUS and VCONN Control register.
Before closing the VCONN switch, the TCPM must make sure the voltage on VCONN pin is at a valid level. When opening the VCONN switch by clearing the ENABLE_VCONN bit, the TCPM software must make sure voltage on VCONN pin is at valid level until after VCONN switch is opened and then, if desired, can remove the voltage from the VCONN pin. Removing the voltage on VCONN pin before Vconn switch is opened will result in a false VCONN fault condition.