I do know it has been some time since this query has been requested initially however I am nonetheless seeing this query come up, and it has been my looking for a solution to a query like this which introduced me right here.
USB Y-cables violate the USB specs and so solely work to offer extra energy to units that additionally violated the USB specs. It ought to solely be a shock to those who know little about how USB works when or if these USB Y-cables fail to offer extra energy to an connected gadget than when linked to a bunch with out the Y-cable. There are methods to make a form of USB Y-cable to offer extra energy to a tool when connected to a USB host that doesn’t present adequate energy, and achieve this with out violating the USB specs. Answering that although is out of scope for this query since that applies to telephones and tablets that should not have Lightning ports.
I will see many complaints on how Apple does issues which are “non-standard” however from studying the USB specs Apple really complies with the USB specs very properly. Their thought on how their USB-An influence bricks handshakes with their iDevices may not be the identical manner different producers do their handshaking nevertheless it doesn’t seem to violate the USB specs. The unique put up mentions getting 900 mA from a USB 3.x port and 500 mA from a USB 2.0 port however these aren’t maximums, these are minimums. A number laptop should provide no less than 900 mA from a USB 3.x port and 500 mA from a USB 2.0 port to be thought-about in compliance with the USB specs. USB ports on Apple computer systems will provide greater than this, and it seems varied computer systems from different producers will as properly.
USB 2.0 and USB 3.x enable for units to barter for as much as 1.5 amps earlier than having to resort to USB-PD or USB-BC to barter for extra. As greatest I can inform Apple computer systems and iDevices use USB-PD to barter for as much as 12 watts, or 2.4 amps, of energy to the iDevice. With out help for USB-PD, or no matter it’s that Apple is utilizing, the speed of cost will probably be restricted to 2.5 watts (500 mA), 4.5 watts (900 mA), or 7.5 watts (1.5 A). The USB spec permits as much as 2.4 amps to peripherals linked to hosts by USB-A and Apple computer systems will fortunately provide this. Or no less than these constructed after the USB-BC and USB 2.0 specs have been revealed.
Should you want energy to your iDevice whereas linked to some peripheral gadget then using a lot of Lightning dongles will enable this. Apple builds a wide range of such dongles, as do producers that Apple partnered with. These dongles could have a Lightning port for as much as 12 watts of energy and a port for the peripheral. Examples for such ports embody HDMI, USB 3.x, Ethernet, and 1/8″ audio for headphones and headsets.
Connecting an Apple iDevice with a Lightning port to a pc that doesn’t present 12 watts does current an issue if the customers needs each information switch and 12 watts to the iDevice. So far as I can inform there isn’t a Lightning dongle that may cut up out the ability and information so that somebody can plug in a 12 watt energy brick to energy an iDevice whereas additionally it is nonetheless capable of preserve a USB connection to a pc.
Generally the issue is not that the pc is incapable of offering the ability Apple iDevices and their customers need, it is that the pc and iDevice aren’t talking the identical language on negotiating the ability switch.
From what I’ve seen from my analysis to this point a USB dock or hub isn’t prone to allow a pc to offer extra energy to an Apple iDevice. The dock or hub may be getting energy from someplace apart from the host laptop however it’s nonetheless the host laptop that’s managing the ability switch. The pc should nonetheless communicate the identical language because the iDevice to barter greater than 7.5 watts of energy. A USB hub or dock may have the ability to present 2.4 amps to linked units however an iDevice is not going to draw extra energy than it has been granted permission to attract.
What may enable a connection to a bunch laptop and supply 12 watts to an iDevice is a Thunderbolt dock. A USB-C to Lightning cable plugged right into a USB-C port on a Thunderbolt dock could enable information switch to a Thunderbolt host whereas offering 12 watts of energy. Thunderbolt docks have an unbiased USB-PD controller, like that in a USB-PD energy brick, that doesn’t depend on the host to handle energy supply. The USB-C Thunderbolt ports on such docks will nonetheless help the USB 2.0 protocol that will probably be required to create the connection between the host and the iDevice.
I’ll emphasize that use of a Thunderbolt dock for getting 12 watts of energy whereas sustaining an information connection to an Apple iPhone or iPad is theory. It is an informed guess however nonetheless a guess. I have not examined this principle and I do not (but) have the {hardware} to check this principle. I wrote this prolonged reply principally to make clear what I am seeing as misinterpretations of the USB specs. Whereas that is an older query it’s nonetheless related as we speak and variations on this nonetheless come up.
