Over-voltage and ground fault protection for bus connectors

A system of networked devices, the system comprising:

• a first controller with a USB VBUS terminal and a USB data terminal;
• a second controller with a USB VBUS terminal and a USB data terminal;
• and
• a protection circuit comprising:
• a first USB VBUS terminal couple to the USB VBUS terminal of the first controller;
• a first USB data terminal coupled to the USB data terminal of the first controller;
• a second USB VBUS terminal coupled to the USB VBUS terminal of the second controller;
• a second USB data terminal coupled to the USB data terminal of the second controller;
• a VBUS line electrically coupling the first USB VBUS terminal and the second USB VBUS terminal;
• a data line electrically coupling the first USB data terminal and the second USB data terminal;
• an interrupter arranged in the VBUS line or in the data line, wherein operation of the interrupter electrically interrupts the VBUS line or the data line;
• a control circuit with a switch, the control circuit electrically connected to the first USB VBUS terminal and controlling the interrupter, wherein the switch generates an interrupt signal to cause operation of the interrupter;
• wherein the control circuit comprises a first branch with a breakdown member defining a first threshold voltage and a second branch with a first comparison member to compare a voltage at the first USB VBUS terminal to a second threshold voltage, the two branches connecting to the first USB VBUS terminal wherein the breakdown member connects directly to the first USB VBUS terminal and the switch generates an interrupt signal if:
• a voltage at the first USB VBUS terminal causes a voltage drop over the breakdown member exceeding the first threshold voltage, or
• a voltage at the first USB VBUS terminal causes a voltage applied to the first comparison member less than the second voltage threshold.