Originally Posted By: K447
Even when the USB hub is connected to a modern Mac which itself could support and negotiate the fast 1amp charging of a directly connected iPhone, when connected through the powered hub the iPhone seems to limit itself to the more pedestrian 500ma charge rate.

Many USB hubs have power supplies that can deliver more than 500ma in aggregate, but I didn't find anything in the Mac or iPhone characteristics that would allow the iPhone to negotiate and draw the additional power from a USB hub.


That's because >500mA is not in the USB standard. Apple uses vendor-specific extensions to request >500mA, hence why it only works with apple devices.

There *are* specs for higher power charging from hubs (up to 1.5A) but this requires extra circuitry in the device to do the dance with the data lines that allows you to identify this.

As, for signal integrity reasons, this generally needs to be within the USB PHY, there's a lag of several years between the standard being made and chips that support the standard getting into phones.[/quote]

Quote:

Must an iPhone or iPad be directly connected to a Mac in order to utilize the higher charging rates? Or is there a way to do so through a (very up to date) USB hub?


I'm not aware of any hubs that would support that I'm afraid. The "solution" is an externally powered thunderbolt display frown