6 ms·
240W with USB-C operates at 48 volts.
by bitcraft 5y ago
240W with USB-C operates at 48 volts.
- zw123456 5y agooh snap, I should have read up on that. That's interesting though, same as telco.
- SV_BubbleTime 5y agoIt’s not really the same. The 48VDC of USBC is switched and will be constantly monitored for over or unusual current. A telco doesn’t care and will allow draw to its full potential all the time.
- yummybear 5y agoIs this safe for humans? Like if my daughter were to suck on the cable.
- atonse 5y agoUsually it negotiates up (thats what USB PD is) Like the device it’s plugged into actually has to communicate and negotiate that it wants something higher. Until then it’ll just be I think 5V and up to maybe 1amp? (5W)
- zw123456 5y agoAlso, old timey phone lines, like back in the day when you plugged a phone into the wall, that had 48V DC on it. But not 5A, mor3 like 600ma. But in theory, not enough to kill.
- SV_BubbleTime 5y ago48 approaches but usually doesn’t exceed what it takes to enter dry skin. But also USB-PD doesn’t start at 48VDC. And it is constantly monitoring for shorts. So if you did manage to get shocked it would only be for milliseconds.
- rasz 5y agoYou did have a phone landline at one point in your life, right?
- SV_BubbleTime 5y agoYour daughter would first have to enumerate and negotiate to switch from 5VDC to 20-48V of USB-PD. So if she can do that with her mouth, you have other things to worry about. (She’s an android, not some colorful euphemism).
- onetwentythree 5y agoYes. Power supplies up to 60VDC are typically designed to fall under SELV and are considered intrinsically safe. SELV requires isolation and a single fault tolerant design. Here is some additional info: https://www.edn.com/what-does-selv-mean-for-power-supplies/ https://www.edn.com/what-does-selv-mean-for-power-supplies/ I doubt the USB-C power negotiation feature is specifically a safety function, but as other comments have pointed out it makes the system even safer. I haven’t looked at the spec, but I wonder if there is any functionality that prevents a power supply from applying 48V all the time. i.e. is it possible to deliver a functional charger that is not SELV and has no power negotiation?
- detaro 5y agoit's not, since a device has no obligation to be able to handle 48V input.