Thread: sony prsa-ac1 ac adapter specifications?
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Old 10-16-2010, 06:28 PM   #32
etienne66
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I should have read that Wikipedia article a bit more.

Quote:
Charging Specification, the USB specification required that devices connect in a low-power mode (100 mA maximum) and communicate their current requirements to the host, which would then permit the device to switch into high-power mode.
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There are also devices at the host end that do not support negotiation, such as battery packs that can power USB-powered devices; some provide power, while others pass through the data lines to a host PC. USB power adapters convert utility power and/or another power source (e.g., a car's electrical system) to run attached devices. Some of these devices can supply up to 1 A of current. Without negotiation, the powered USB device is unable to inquire if it is allowed to draw 100 mA, 500 mA, or 1 A.
It sounds like some of these chargers probably don't allow for negotiation and the Sonys appear to require it.

Etienne66
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