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Original question:

TPS2543: Operation Mode for dynamically adjust the current limit

TPS2543: TPS2543EVM-064 question

sp lee
Prodigy 110 points
Part Number: TPS2543

Hi,

I'm testing the TPS2543EVM evaluation board and set it to CDP mode. I connect its output to a Lenovo 5" tablet and monitor the battery charging status. When I connect the input of this board to a 5V DC supply, my tablet shows charging over AC and I suppose the board is indeed in CDP mode with maximum 1.5A charging current. However, when I connect the input to a PC USB port, the tablet shows "charging over USB". I think the board is no more in CDP mode and the maximum current is only 500 mA.

So my question is besides the control pins what else can make the board out of the CDP mode? (into SDP mode?)

  • 0
    TI__Mastermind 28850 points

    Hello,

    The expert covering this device is currently out of the office but will be back next week. Please expect a delay in a response. Thanks in advance for your patience.

  • 0
    TI__Genius 9630 points

    Hello,

    The scenario where the TPS2543 will override the CTL pins is during Wake on USB. This is the case where the system tries to go to DCP-auto and the TPS2543 will override the request and keep the data lines (DP/DM) connected, in order to wake the system up from sleep mode. 

    Otherwise, to change from CDP mode, a change to the CTL/ILIM_SEL pins is required. 

    The TPS2543 could still be in CDP mode and the tablet could be pulling lower current. The TPS2543 will offer up to 1.5A in CDP mode but it is up to the attached device to pull that amount of current.  

    Thanks,

    Emma

  • 0 in reply to Emma Hoying
    Prodigy 110 points

    Hi Emma,

    Thanks a lot for the explanation. For our product it is essential that the TPS2543 maintain the CDP mode so that a charging current larger than 500 mA can be delivered. So I would like to understand further about this issue. After the wake-up period as you mentioned, would the TPS2543 automatically enter CDP mode again? I suppose the tablet would wake up for sure.

    On the other hand, is there any timing criteria that we should meet on the USB host side? For example, should the host wait for a while before the enumeration process after the cable plug-in?

  • 0 in reply to sp lee
    TI__Genius 9630 points

    Hello,

    During Wake on USB, the TPS2543 will override the command to go into DCP_Auto in order to keep the data lines connected (to be able to wake up the system using the data lines). So, the TPS2543 will ignore the sleep command and stay in CDP. It would never leave CDP. 

    If the TPS2543 is in CDP mode, only changing the CTL/ILIM pins will take the TPS2543 out of CDP. So the TPS2543 can still be in CDP even if an attached device chooses not to pull the max current of 1.5 A. 

    The TPS2543 works with both BC1.2 compliant and non compliant devices, and as a USB port controller, will have the appropriate timings for each mode. 

    Thanks,

    Emma