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Date: Tue, 02 Nov 2010 08:50:07 -0400
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From: Hamid Wasti <hwasti@lm50.com>
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Subject: Re: [LML] Re: IPAD Charging
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A "Dedicated Charging Port" is intended to be a port that is only a 
charger/power-source and does not have any USB functionality. The D+ and 
D- pins are shorted together on this port to indicate that it is a 
dedicated charging port. The downstream device, the iPad in this case, 
detects that the D+ and D- pins are shorted together and that it is OK 
to draw up to 1.8A (9W at 5V) from the bus.

However, that is not the only way a device can legally draw more than 5W 
from a port. The Battery Charger spec defines some other modes as well 
that allow a device to negotiate up to 1.5A (7.5W at 5V) of current from 
a compliant bug and draw this current while also communicating on the bus.

Regards,

Hamid

billhogarty wrote:
> For Hamid:
>
> Appreciate your detailed explanation on this topic.
>
> One question:  When a hub or charger has a "dedicated charging 
> capability", is it identified in any special way?
>
> Thanks, Bill Hogarty
>
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