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Samsung Galaxy Tab does not show charging when TPS2541 is configured in CDP mode.

Daniel Zajc
Prodigy 30 points
Other Parts Discussed in Thread: TPS2541, TPS2546

We are designing a product that uses an Freescale iMX28 with USB Host connected to a TPS2541 configured in CDP (Charging Downstream Port) mode.

The Samsung Galaxy Tablet (SM-T705Y) plugs into our products USB Host connector and appears to negotiate with the TPS2541. The Galaxy Tab battery status page indicates that the battery is still "Not Charging". However the current drawn from our 5V USB rail is 0.95Amps. Note our Linux cpu successfully enumerates a USB endpoint.

How can this be?

If I apply the same process described above to an Apple iPad the iPad negotiates properly and draws 1.4Amps and the battery status indicates "Charging"

Can anyone help me out with this issue?

Regards,

Daniel

  • 0
    TI__Mastermind 42795 points

    Based on data collected from our newer devices (TPS2546), it shows that some of the aforementioned tablets will charge at around 1 amp in CDP mode (CDP fast charge). However, our data does not indicate whether the devices charging indicator was illuminated or not. The devices which charged at over 500mA in CDP mode would also charge at the same rate with the OEM charger (no data).

    Devices only charging at 500mA in CDP mode would charge at a higher rate with the OEM charger and TPS2546 in DCP auto mode (which will present Samsung divider mode 1.2V/1.2V).

    Maybe the vendor can explain how his charging indicator works?

  • 0 in reply to Eric Wright
    Prodigy 30 points

    Thanks for your f/b Eric.

    I am currently quizzing Samsung about this issue.

    If I config the TPS2541 in DCP (Dedicated Charging Port) mode instead of CDP the Samsung Tablet correctly reflects the charge status and draws 1.4Amps. But this is not what we want. We need thethering and charging.

    The TPS2541 was designed to work in CDP mode with 1.5A current draw. what is going on here?

    If I move to the TPS2546 I would like to know that it will work before getting more boards made.

    Regards Daniel