A number of Android tablets are powered through the Micro B USB port but also provide USB Host support through the same port (e.g. Motorola Xoom 2, Acer A510/700). I need to be able to use USB Host support while charging, at the full power the device accepts (or at least sufficient power to keep the tablet from draining under modest use).
I have rigged up a system with splitter cables and a powered hub. This works on some devices (HP TouchPad, Archos) but not others (Google/Asus Nexus 7, Coby Kyros). And when it does work, it slow charges (probably at USB 2's 500ma).
How can this problem be solved? Are there any solutions on the market that will solve my problem? I see there are some USB chips by Silego (their Battery Charger ID line) that may solve the problem, but I don't know of any cables, hubs, etc. that use it.
Best Answer
Apparently it is possible to charge the Host-Device! --> http://en.wikipedia.org/wiki/USB_On-The-Go
Under "OTG Micro Plugs" it says that a USB OTG cable with a 36.5 kΩ resistor between Pin 4 (I suppose its pin 4) and Pin 5 allows you to connect a B-Device (Slave) and (!) a Charger to the Smartphone/Tablet.
The Phone and the B-Device can be supplied by the external power source.
USB-Power Specifications: http://www.usb.org/developers/docs/devclass_docs/batt_charging_1_1.zip (updated link)