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According to this picture from TI enter image description here

and Type-C specification, I am wondering where is the protection for these super speed differential lines

As it seems that when an improper removal happens, there is a chance that VBUS might contact the adjacent differential lines, and I don't think ESD protectors on these lines will protect them from shorting to VBUS.

And I checked the common MUX's datasheet used on these lines(HD3SS3220), the absolute maximum rating voltage on these lines is 2.5V, so MUX won't protect VBUS for PHY.

Edit: The picture is from this article: The problem with short-to-VBUS protection integrated into your USB Type-C™/USB Power Delivery controller

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  • \$\begingroup\$ please provide a source (link) for your image. \$\endgroup\$
    – Christianidis Vasilis
    Commented Feb 7, 2023 at 15:07
  • \$\begingroup\$ Your link is an advertisement for a TI IC that does short to VBUS protection. I have never used it, but if you are concerned about this problem, TI's solution seems like a good place to start. \$\endgroup\$
    – user1850479
    Commented Feb 8, 2023 at 3:43
  • \$\begingroup\$ It only provides protection for CC lines, not RX,TX lines that next to VBUS \$\endgroup\$
    – Halry
    Commented Feb 8, 2023 at 5:43
  • \$\begingroup\$ This is a good question. Apparently the current specification for Type-C connector has a electromechanical flaw, somebody got circuits fried, and TI provided some solution to this "improper removal". \$\endgroup\$
    – Ale..chenski
    Commented Feb 21, 2023 at 6:26

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Modern (recommended) circuitry of USB-C connectors use AC-decoupling caps (0.22/0.33uF) on all susperspeed lines, Tx and Rx, so the VBUS touch on these pins does not expose IC pads to dangerous DC levels and causes only a ESD-like event. However, the CC/SB signals are DC signals, that's why TI chip protects only these wires.

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  • \$\begingroup\$ But superspeed lines only have capacitors on TX differential lines. What about RX lines? \$\endgroup\$
    – Halry
    Commented Feb 16, 2023 at 7:21
  • \$\begingroup\$ Oh, I see, there is an ECN for USB3.1, adding RX AC capacitors, still optional though. \$\endgroup\$
    – Halry
    Commented Feb 16, 2023 at 7:29
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You do not mention a specific product. You ask generally for USB type C protection from such events.

where is the protection for these super speed differential lines

As a designer of the PCB, you are responsible to make the protection for such events. Having said that, you might not need or want to make such protection and you cannot know from the start if the product you are using has such protections.

The USB C connector is just a connector, it does not come with surge protections. You/the designer should implement those.

It is the same thing for maximum current protection. The connector does not stop the USB from drawing more amps that the USB is capable of. The designer should use a IC to limit the current drawn.\

EDIT

The pins you mention that could be shorted, what is the voltage they carry and are they tolerant to the voltage of the short?

If both signals carry for example 3.3V and they are 3.3V tolerant (or 5V tolerant), then there is no issue shorting them and you should not need protection from that. After all the short happens when you plug, unplug the connector and not during operation (I hope) so it wont affect your functionality.

So you should check the voltage tolerance of these pins.

Also, if you worry for a connector too much and it seems unreliable to use, choose another USB connector.

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  • \$\begingroup\$ I know I need to add protection for these differential links if I need to use these pins, but I can't find any exists components for short-to-VBUS circumstance, only ESD components for these pins. So I am wondering whether these pins need to be protected from short-to-VBUS circumstance? \$\endgroup\$
    – Halry
    Commented Feb 8, 2023 at 1:48
  • \$\begingroup\$ the ESD components you find should protect from such shorts. Their job is to sink current (if they detect overvoltage) for a short period of time. Check the datasheets if they can support sinking for example ~2A for ~100ms, or similar currents and timings. The usb port will not be shorting all the time. If it does, this means it does not fit your design and you should use another connector. There are bad connectors as well. You dont have to use them. \$\endgroup\$
    – Christianidis Vasilis
    Commented Feb 8, 2023 at 7:50
  • \$\begingroup\$ @ChristianidisVasileios, "Check the datasheets if they can support sinking for example ~2A for ~100ms" - Did you check yourself? Do you know that ESD devices are designed to protect against ESD events, which are 1000 times shorter? ... "choose another USB connector" - do you know that USB-C connector is fully mechanically specified, with contact geometry made the same by manufacturers? I would strongly suggest to delete your answer as groundlessly patronizing and misleading. \$\endgroup\$
    – Ale..chenski
    Commented Feb 21, 2023 at 6:17

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