4 ms·

That’s incorrect on all three counts. Some “low wattage” specification USB-C devices are compliant with USB-C but are only compatible with USB-A power bricks b

by hedora 3y ago

That’s incorrect on all three counts. Some “low wattage” specification USB-C devices are compliant with USB-C but are only compatible with USB-A power bricks because thet require 5V: https://www.reddit.com/r/UsbCHardware/comments/c3q4s6/why_do_some_usbc_devices_not_charge_with_a_usbc/ https://www.reddit.com/r/UsbCHardware/comments/c3q4s6/why_do... Some USB-C cables are only 31 watts, and some devices can’t charge with less than 60W: https://www.macworld.com/article/234030/how-to-tell-whether-a-usb-c-cable-can-carry-high-wattage-power-and-thunderbolt-3-data.html https://www.macworld.com/article/234030/how-to-tell-whether-... Example brands from the above two links include JBL, Schooshe, and Apple. I’ve hit similar problems with all my USB-C devices.

scarface_74 3y ago
And your Reddit link also has a comment suggesting using a USB A to USB C adapter. Those are also non compliant https://hackaday.com/2022/12/27/all-about-usb-c-illegal-adapters/ https://hackaday.com/2022/12/27/all-about-usb-c-illegal-adap... There is a certain combination of cable+adapter+device that can ruin your device. I don’t remember the details. I heard about it on the Accidental Tech Podcast
zlsa 3y ago
> Some “low wattage” specification USB-C devices are compliant with USB-C but are only compatible with USB-A power bricks because thet require 5V: This is because they are not USB-C compliant, despite physically featuring a USB-C port. The USB-C spec calls for any USB-C sink (i.e. device that consumes power) to include a pull-down resistor (Rd in the diagram on page 4: https://www.ti.com/lit/wp/slyy109b/slyy109b.pdf?ts=1696900396907 https://www.ti.com/lit/wp/slyy109b/slyy109b.pdf?ts=169690039...) Devices that do not include this resistor, and are therefore unable to be powered with a USB-C to USB-C cable, are noncompliant and should not exist. > Some USB-C cables are only 31 watts, and some devices can’t charge with less than 60W As seen in [0], page 37, even USB 2.0 C-to-C cables will support USB-PD at 3A: https://host.zlsadesign.com/HJU_Drfba.png https://host.zlsadesign.com/HJU_Drfba.png The USB-PD handshake is performed independently of the cable, and uses the CC wire that is mandatory even in USB 2.0 C-to-C cables (page 76 of [0]): https://host.zlsadesign.com/Bk62vSMZp.png https://host.zlsadesign.com/Bk62vSMZp.png You're right about the 60W point. Anecdotally, every device I've ever tried to charge has had no problems at 60W (although of course they'll charge more slowly than if they had 100W), but this is definitely not guaranteed. 0: https://www.usb.org/sites/default/files/USB%20Type-C%20Spec%20R2.0%20-%20August%202019.pdf https://www.usb.org/sites/default/files/USB%20Type-C%20Spec%...

by hedora 3y ago

scarface_74 3y ago

And your Reddit link also has a comment suggesting using a USB A to USB C adapter. Those are also non compliant https://hackaday.com/2022/12/27/all-about-usb-c-illegal-adapters/ https://hackaday.com/2022/12/27/all-about-usb-c-illegal-adap... There is a certain combination of cable+adapter+device that can ruin your device. I don’t remember the details. I heard about it on the Accidental Tech Podcast

zlsa 3y ago

> Some “low wattage” specification USB-C devices are compliant with USB-C but are only compatible with USB-A power bricks because thet require 5V: This is because they are not USB-C compliant, despite physically featuring a USB-C port. The USB-C spec calls for any USB-C sink (i.e. device that consumes power) to include a pull-down resistor (Rd in the diagram on page 4: https://www.ti.com/lit/wp/slyy109b/slyy109b.pdf?ts=1696900396907 https://www.ti.com/lit/wp/slyy109b/slyy109b.pdf?ts=169690039...) Devices that do not include this resistor, and are therefore unable to be powered with a USB-C to USB-C cable, are noncompliant and should not exist. > Some USB-C cables are only 31 watts, and some devices can’t charge with less than 60W As seen in [0], page 37, even USB 2.0 C-to-C cables will support USB-PD at 3A: https://host.zlsadesign.com/HJU_Drfba.png https://host.zlsadesign.com/HJU_Drfba.png The USB-PD handshake is performed independently of the cable, and uses the CC wire that is mandatory even in USB 2.0 C-to-C cables (page 76 of [0]): https://host.zlsadesign.com/Bk62vSMZp.png https://host.zlsadesign.com/Bk62vSMZp.png You're right about the 60W point. Anecdotally, every device I've ever tried to charge has had no problems at 60W (although of course they'll charge more slowly than if they had 100W), but this is definitely not guaranteed. 0: https://www.usb.org/sites/default/files/USB%20Type-C%20Spec%20R2.0%20-%20August%202019.pdf https://www.usb.org/sites/default/files/USB%20Type-C%20Spec%...