The CC pins on the USB Type-C connector serve many functions; one of the functions is to be a provider of power to active cables. Active cables are required when desiring to pass greater than 3 A of current on the V_BUS line or when the USB Type-C port uses the super-speed lines (TX1+, TX2–, RX1+, RX1–, TX2+, TX2–, RX2+, RX2–). When CC is configured to provide power, it is called VCONN. VCONN is a DC voltage source in the range of 3 V to 5.5 V. If supporting VCONN, a VCONN provider must be able to provide 1 W of power to a cable; this translates into a current range of 200 mA to 333 mA (depending on your VCONN voltage level). Additionally, if operating in a USB PD alternate mode, greater power levels are allowed on the VCONN line.

When a USB Type-C port is configured for VCONN and using the TPD4S311, this VCONN current flows through the OVP FETs of the TPD4S311. Therefore, the TPD4S311 has been designed to handle these currents and have an RON low enough to provide a specification compliant VCONN voltage to the active cable. The TPD4S311 is designed to handle up to 400 mA, while the TPD4S311A is designed to handle up to 600 mA of DC current to allow for alternate mode support in addition to the standard 1 W required by the USB Type-C specification.