12v iPad Charger

Making a 12v iPad Charger to use with our off-grid solar system

Date 01 August 2012
Views 11,903
Time to read 2 minutes read

Following the 4th Apple, iPad charger failing and not wanting to spend even more money with Apple to replace them we decided to try to make 12v powered chargers to make use of the excess PV power we now have during the daytime to charge the iPads and other devices which charge via USB.

I have a couple of ready-made USB car chargers but these will not charge the iPad due to the iPad needing a control voltage on both of the data pins which most commercial 12V chargers don’t seem to supply.

Click to view PDF version

The circuit schematic (click for PDF) shows the new charging circuit diagram which uses a Texas Instruments PTN78020 6-A, Wide-input adjustable switching regulator to bring the input voltage down to 5V and then voltage dividers to supply the data lines with the correct voltage. 

Testing a working iPad charger gave the following voltages:

USB Pin 1: 5V
USB Pin D- : 2.75V
USB Pin D+: 2.065V

From these, we calculated the nearest resistor values to create the voltage designers and then built 3 chargers for use around the house.

The completed charger circuit top view shows power regulator and smoothing caps.

Circuit Layout

The completed charger circuit base view showing voltage dividers.

Circuit Layout

The completed charger is fitted into a plastic box with a power switch.

Circuit Layout

Tags: Apple Projects

2 Comments

  • User Image

    Ed Brookshire

    21 January 2019 at 6:14 pm

    Are kits, parts, or completed boards available?

    • User Image

      Brian

      21 January 2019 at 6:23 pm

      Ed, I am sorry but I don't have any kits or completed boards for this project.


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