First off all, sorry if this is really long, I just want to make sure I include everything. I am working on a boost circuit to power a usb port from a Li-Po to charge a cell phone or iPod on the go. The problem I have is that the charger seems to work for all devices except iPhones. On the iPhone, the battery symbol has a plug like when the battery is fully charged, rather than the lightning bolt that it usually there when charging. The battery percentage also stays the same so it isn’t charging. I read through the info about iCharging on the minty boost tutorial and I set up the voltage divider using a 43k/51k on D- and 75k/51k on D+. That should be fine, because the LTC3428 should be able to supply up to 2A @ 5v.
A screenshot of what the iPhone looks like when it is plugged in.
http://farm8.staticflickr.com/7405/1126 … 391f_n.jpg
I just want to see if anybody knows what the different symbol means on the iPhone. I don’t know if it means that the phone doesn’t recognize the charger, or if the charger wasn’t supplying enough current. Also without anything hooked up to the usb port the data pins read ~2.7 and 2.4V, but once I hooked up the iPhone they fell to ~2.5 and 1.8V. Not exactly sure why they fell so low but maybe that could be the problem.