Thread: USB Wall Charger
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Old 07-11-2010, 08:16 PM   #28
3d0g
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Join Date: Jul 2010
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Quote:
Originally Posted by DaleDe View Post
Actually there is no requirement for USB to deliver more than 500mA and anyone who expects a computer to power their device cannot guarantee that more than 500 mA is available. So although the spec has some complicated variations and under certain conditions might only be able to supply 100mA to a given device the 500mA is certainly a reasonable minimum if you don't use a hub. You cannot expect any computer to supply 1.5 A. You might get it but then again you might not.
There's no guarantee of 500mA either. As I said, per the USB Battery Charging spec, the host negotiates with the device. If the host only has 100mA available, the device will deal with what it can get.

A simple USB wall charger normally doesn't have the intelligence and when the device does not get a response from its protocol queries, it just pulls its full requirement - 700mA with the kobo.
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