Current controlled architecture for a Vconn switch

A Universal Serial Bus Type-C (USB-C) controller comprising:

• a USB Power Delivery (USB-PD) subsystem comprising a Vconn switch, wherein the Vconn switch comprises:
• a first transistor and second transistor coupled in series between a Vconn terminal and a communication channel (CC) terminal, the first transistor including a source coupled to the Vconn terminal;
• a replica switch including a source coupled to the Vconn terminal;
• a replica current generator including a first input coupled to a drain of the first transistor and a second input coupled to a drain of the replica switch, wherein the replica current generator is operable to match a replica current through the replica switch to a current supplied through the first transistor and the second transistor to the CC terminal;
• and
• a resistance control module operable to control an in-rush current to the CC terminal, wherein the resistance control module comprises:
• a third transistor including a gate coupled to an output of the replica current generator, a source coupled to a first current supply, and a drain coupled to ground;
• and
• a current inverter coupled to the first current supply and to a second current supply, wherein a digital output of the current inverter is coupled to control a gate of the second transistor.

A method of operating a Vconn switch for a Universal Serial Bus Type-C (USB-C) controller, the method comprising:

• receiving an input voltage on a Vconn terminal coupled to a communication channel (CC) terminal through a first transistor connected in series with a second transistor;
• providing the input voltage to a source of the first transistor and to a source of a replica switch coupled to the Vconn terminal;
• matching a current, supplied through the first transistor and the second transistor to the CC terminal, to a replica current through the replica switch generated by using a replica current generator, the replica current generator including a first input coupled to a drain of the first transistor and a second input coupled to a drain of the replica switch;
• and
• controlling an in-rush current to the CC terminal by using a digital output from a resistance control module, wherein controlling the in-rush current comprises:
• providing an output of the replica current generator to control a gate of a third transistor, wherein the third transistor includes a source coupled to a first current supply and a drain coupled to ground;
• and
• providing the digital output from a current inverter to control a gate of the second transistor, wherein the current inverter is coupled to the first current supply and to a second current supply.