Thread: A 'possible' AC charger?
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Old 04-11-2009, 07:43 PM   #27
Stitchawl
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Quote:
Originally Posted by gwynevans View Post
The USB spec includes a negotiation phase which includes specifying the power (current) requirements of the device. While the 'dumb' chargers just make the power available, I'm not 100% sure, but I'm fairly sure that the Sony finds that the negotiation attempt with them fails and declines to draw the power, whereas when used with a real USB controller, negotiation suceededs and battery charging starts.
Now this is more like it! (I don't understand it, but at least I can see it's addressing the point of the question! ) If the purpose of the 'negotiation' is to specify the power requirements, and both chargers are putting out 5.2V with the same polarity, I wonder what could be missing from the negotiation to cause the non-acceptance of the charge?


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