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I designed a circuit (shown belown) which has its power provided through a USB-C connector (5 V/3 A).

Lots of engineers recommend add providing diode/Zener such as NUF2221W1T2G.

I only use the USB-C power (Vbus), not communications. So I don't use the USB-C data bus (D+, D-).

Can I just use a diode/Zener to protect Vbus and leave D+ and D- disconnected (floating) in my circuit?

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    \$\begingroup\$ Yes, you can, but it really depends how much current your device needs. If it needs 3A, then you can't simply expect to connect your device to any USB source without negotiating that your device needs 3A. Plugging your device into a standard laptop which can't provide 3A might end up with a broken laptop. \$\endgroup\$
    – Justme
    Commented Jan 12, 2023 at 10:29
  • \$\begingroup\$ Thanks @Justme 's reply. I got it. I know that most laptops can only supply 5V / 0.9A according to the standard of USB 3.0 nowadays. So this circuit need 5V / 3A adapter, I'll mention user this thing. In conclusion, disconnect seems to be feasible, right? \$\endgroup\$
    – curlywei
    Commented Jan 12, 2023 at 11:12
  • \$\begingroup\$ The USB-C host port will advertise its current capability at 5V using pullup resistors on CC1/CC2. So you can measure the voltage you see on those pins to check that 3A is available. \$\endgroup\$
    – Finbarr
    Commented Jan 12, 2023 at 11:49

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