Usually a competently designed USB-C input should have over-voltage protection and short-to-VBUS protection for over 20V (25-28V). Putting out any voltage before detecting a sink is breaking the standard, but a charger putting out over 20V without any PD negotiation would be absurdly wrong and dangerous...

So there are non-compliant plugs, but if your device breaks just because it sees a regular PD VBUS voltage (5-20V) then it means that it was designed badly - either through ineptitude or foolish cost saving.

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cesarb 8 days ago | parent [-]

> Putting out any voltage before detecting a sink is breaking the standard

To be pedantic, I believe that only applies to USB-C sockets; AFAIK, a USB-C plug (like on a USB-A to USB-C cable) can in some cases put out 5V (but only 5V) before detecting a sink.

> but if your device breaks just because it sees a regular PD VBUS voltage (5-20V) then it means that it was designed badly

The standard was designed so that devices never see anything over 5V unless they ask for it, so why should a non-PD device (for instance, a mouse) care about it? In some cases (like a USB-A mouse plugged into a USB-A to USB-C adapter), the device might even have been designed and built when USB was 5V only.

	▲	stephen_g 8 days ago \| parent [-]
		A USB-A device obviously wouldn’t have been designed for anything more than 5V. But anything with a USB-C socket is living in a world where a faulty source could accidentally give it a higher voltage. At that point it’s just about your tolerance for risk - maybe for something worth $100 or less and not supporting PD you can skip out and if there’s a faulty charger that blows it up then whatever, but for something selling for a few hundred dollars (like the Switch, or phones, etc.) it’s worth the 50c in BOM cost for the extra protection…