8.3.5.2 USB Type-C Port Stays Connected during an IEC 61000-4-2 ESD Strike

The TPD8S300A will also make sure the USB Type-C ports stay connected, even during an IEC 61000-4-2 ESD strike, whereas the TPD8S300 has the potential to cause a USB Type-C port disconnect during an IEC 61000-4-2 ESD strike. In TPD8S300, in some PCB layouts an IEC 61000-4-2 ESD strike would cause TPD8S300 to go into the OVP state. In TPD8S300, the CC OVP recovery time was 21ms minimum. This means that if an OVP happened in TPD8S300, a USB-C disconnect was guaranteed to happen, because the maximum USB Type-C port disconnect time for sources and sinks is 20ms max in the USB Type-C specification. However, in TPD8S300A, the CC OVP recovery time is 0.93ms typical. For TPD8S300A, the OVP FET will turn back ON much faster than a sinks minimum disconnect time, which is 10ms. So even if an IEC 61000-4-2 ESD strike causes an OVP in TPD8S300A, the new CC OVP FET recovery time of 0.93ms will not cause a disconnect on the USB Type-C port for a sink.

For a source port connected to a sink with a TPD8S300A, if an IEC 61000-4-2 ESD strike occurs that causes an OVP event, even an OVP recovery time of 0.93ms could cause a disconnect, because for source USB Type-C ports, they have a minimum disconnect time of 0ms in the USB Type-C specification. So the CC OVP FET in TPD8S300A would open up and hide the PD controllers RD for 0.93ms, causing a potential for a disconnect on the source USB Type-C port. To solve this problem, TPD8S300A turns on its dead battery RD resistor in an OVP event caused by an IEC 61000-4-2 ESD strike while the CC OVP FET is OFF. This makes it so even during this OVP event caused by IEC ESD, the source port connected to the sink port with TPD8S300A will always see an RD resistor. Therefore, even if the source port has an extremely low tSrcDisconnect time close to 0ms, it will remain connected because an RD resistor is always present on its CC pin.