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TPS2544 with iphone and ipad

Prathyusha Kamarajugadda
Prodigy 20 points
Other Parts Discussed in Thread: TPS2544

Hello all,

I am using TPS2544 for my application, which is to charge mobile devices in DCP mode from any USB power source. My application is specifically for Apple devices. So I set the IC in forced divider mode (CTL1, CTL2, CTL3 - 1,0,1). I observed that when an iPhone is connected the IC is in Divider 1 mode and it charges at 1 A approx, but when I connect iPad, the IC doesn't shift to Divider 2 mode and the iPad still takes only 1 A. 

"TPS2544 will automatically switch between the Divider1 and Divider2 schemes based on charging current drawn by the connected device. Initially the device will set the data lines to Divider1 scheme. If charging current of >750mA is measured by the TPS2544 it switches to Divider2 scheme and test to see if the peripheral device will still charge at a high current. If it does then it stays in Divider2 scheme otherwise it will revert to Divider1 scheme" - (in datasheet)

Is there any version of the IC where I can set it specifically for iPhone and iPad DCP modes? I can not use Auto-Detect mode due to various reasons. Please help!

Thanks,

Pra

  • 0
    TI__Mastermind 42795 points

    DCP auto mode is provided for just what you describe.

  • 0 in reply to Eric Wright
    Prodigy 20 points
    Hi Eric,

    Thanks for your reply. I used the DCP auto mode originally, but I found that iphone is not charging in that mode, but other Android phones are working alright.
    So my guess was that, as iphone has an authentication protocol and because the IC discharges Vout in AutoDetect in the process of identifying the phone, maybe the iphone closed its port by reading a low voltage. Also, while plugging and unplugging the connection to phone I could see the charging symbol very briefly sometimes - for half a second - before it would go away.
    So to eliminate the time delay and to prevent Vout discharge, I had to use Forced Divider mode, where it was charging well. But as I said, it doesn't support iPad full charging.
    NOTE: My circuitry with the IC comes between the iphone cable and the iphone.

    Regards,
    Prathyusha