I have read a bit already about USB C specification. One thing is not clear for me though. Please take a look at this picture:
A device with profile from 1 to 5 can provide a higher voltage on the Vbus. From profile 4 to 5 it is specified that up to 20 V. The question is:
Can the Vbus voltage vary from 12 to 20 V freely or is it always 12V or 20V for profiles 4 and 5? I am not certain about this especially because even the AC adapters for laptops provide 19.5V, meaning that it would be hard (from the power electronics point of view) for a laptop to provide 20 V. Note: take under consideration only USB C to USB C cable connection, not USB A to USB C, as this one clearly can provide only 5V.
When designing a device that would like to be charged from USB C, should it have the ability to be charged from 5V and 12 - 20 V? I would appreciate all help.