Is second voltage divider circuit necessary?

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cadevon
 
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Is second voltage divider circuit necessary?

Post by cadevon »

As I was reading through the iCharging section of the tutorial, it said that in order to adapt the design to provide 2x 2.0V to the data lines they included 4 more resistors.

My question is- why can't you simply use a single voltage divider and connect the two pins to that 2.0V?

Thanks!
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adafruit_support_bill
 
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Re: Is second voltage divider circuit necessary?

Post by adafruit_support_bill »

That would probably work. The current circuit was reverse engineered from a tear-down of an actual Apple charger. Some phones use different voltage on the two pins to signal other charging protocols.

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cadevon
 
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Re: Is second voltage divider circuit necessary?

Post by cadevon »

So what configuration would allow or the most "generic" configuration? having 2.0V lines on the data pins (I assume so since thats how the project was designed and its widely compatible)

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adafruit_support_bill
 
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Re: Is second voltage divider circuit necessary?

Post by adafruit_support_bill »

Since the MintyBoost was released, the USB standards group has put out a standard for how chargers should work. And most of the industry is following it more-or-less. Apple phones and many others work with 2.0v on the data pins. Some phones work better if the two center pins are shorted together as well.

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cadevon
 
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Re: Is second voltage divider circuit necessary?

Post by cadevon »

Ok great thanks for the answers!

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