> 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=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
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
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.
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=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
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
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%...