Author Topic: USB charging and data buses  (Read 856 times)

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Offline gore

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USB charging and data buses
« on: June 28, 2016, 12:14:52 pm »
Hello,

I couldn't find a clear answer to this. I want to charge a camera off of a bicycle 6V 3W generator. I've wired up a simple AC-DC regulator, which works, but not every device charges up with only the Vbus / GND connected on the USB. How should I wire up the D+ D- buses? A resistor divider of some kind, perhaps? The specific device I want to charge draws around 400mA.
 

Offline WaveFunction

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Re: USB charging and data buses
« Reply #1 on: June 28, 2016, 01:07:39 pm »
Many devices check to see if the data lines are shorted together. If the resistance is less than 200ohms then you get up to 500mA charging.

However, newer Apple devices do things a different way. They check the voltage on the two data lines. You need 2V on both lines for 500mA charging, or 2.8V on D- and 2V on D+ for 1A charging.

See this for more info.
 

Offline gore

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Re: USB charging and data buses
« Reply #2 on: June 28, 2016, 01:29:10 pm »
Looks like I will do just fine by shorting the D+/D-. Thanks for the input!
 


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