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TPS2514: The electrical signature is incorrect with Apple

Stefano vairano
Prodigy 80 points
Part Number: TPS2514

I am using a TPS2514 as USB port controller on a power supply of my company that can deliver more than 2.2 Amps at 5V. When a Samsung device is connected the proper electrical signature is showed, but with an Apple Ipad the voltage on D+ and D- lines stays at about 0.9V and the tablet doesn't charge at the correct currrent. The first photo is the Apple charger signature tath can be seen is 2.73 and 2V on D+ and D-, in the second photo is the charger with TSP2514 than output 0.88/0.89 V on D+ and D- with an APple device attached

  • 0
    TI__Mastermind 30000 points

    Hello Stefano,

    Do you have the ability to use an oscilloscope to measure the voltage of VBUS, DP, and DM over a period of time? This would be good information to have for this specific case. Can share both the passing and failing case if possible.

    Also, is the TPS2514 the only thing connected to the DP/DM lins on your system?

  • 0 in reply to Adam Mc Gaffin
    Prodigy 80 points

    Hi Adam, 

    i made a capture with the oscilloscope, the first one is with a Samsung S7 connected and the signature of 0.75V on both line is correct, in the screen the resolution is 0,25V/DIV, in fact 3 vertical step are 0,75V. The second image is when I disconnect Samsung and connect IPAD that the voltage on both line passes from 0,75 to 1 V stable on both lines. CH1 is Dp and CH2 is Dm signal. .

  • 0 in reply to Stefano vairano
    TI__Mastermind 30000 points

    In the schematic, is there anything else connected on the DP/DM lines that would potentially interfere with the charging advertisement? If you look at the scope capture for the iPad, you can see that after the disconnect/connect, the TPS2514 first advertises ~2.3V on both the DP/DM lines then transitions over to only 1V for each connection. 

    Is the iPad unable to charge with the TPS2514?