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Weird problem with Switching regulator and 3rd party Iphone charger circuit

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zenniz

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I'm designing a 3rd party universal charger for any smarts phone that uses 5V, 500mA.
The switching regulator LM2575 ADJ is converting 12V to 5V from a power supply.
I'm able to charge phones like Galaxy S3 and Black berry but not Iphone3 and 4.
The Iphone keeps showing the message " Charging is not supported with this accessories "

The Iphone charges with a healthy amount of ampere when i remove the switching regulator circuit and supply a 5V input to the USB alone with all the resistor.

For both testing, i'm using apple's USB cable.

What is happening?

Charger.png
Testing.png
 

I seem to remember you have to do something to the D+/D- pins on iPhones to make them work. See https://www.ladyada.net/make/mintyboost/icharge.html.

From Wikipedia
Before the battery charging specification was defined, there was no standardized way for the portable device to inquire how much current was available. For example, Apple's iPod and iPhone chargers indicate the available current by voltages on the D- and D+ lines. When D+ = D- = 2 V, the device may pull up to 500 mA. When D+ = 2.0 V and D- = 2.8 V, the device may pull up to 1 A of current.[53] When D+ = 2.8 V and D- = 2.0 V, the device may pull up to 2 A of current.[54]
Click to expand...

Keith
 

As I recall the voltages are critical. You are just putting 2V into the pins, not the voltages I referred to and linked to (2V and 2.8V).

Keith
 

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