I have a Windows tablet and otg adapter that can simultanously charge the device but there isn't enough current flowing to fight the discharge!? I have 4 usb devices attached to my otg usb hub. Can it be the problem? Could a extra powered usb hub solve my problem? Thid isn't helping me (mostly Android):http://forum.xda-developers.com/showthread.php?t=1822653&page=16. Thanks in advance for any help!
Answer
If you have a hub connected to the tablet, the tablet is in host mode, and must be a SOURCE for VBUS. Therefore it can't charge itself. To accomplish what you want you need a special device called "accessory charge adapter". In simplest form it might look like this:
In theory your tablet should discriminate between ID pin grounded (host mode, sources VBUS), ID pin floated (device mode, consumes VBUS), and ID pin = 100-125k, meaning "accessory charger". In this case the tablet should serve as a host, but consume VBUS for internal charging.
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