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TPS2540 EVM CDP Mode

David Wang11
Expert 7400 points
Other Parts Discussed in Thread: TPS2540, TPS2540EVM-623

Trying to use the TPS2540 in CDP mode via the EVM. The EVm is plugged into a host computer (laptop) through J2 and a power supply through J1. There is a tablet PC connected to J3A and a resistive load connected to J3B. What is being seen on the output for charging is that the current is no more than 500mA. It seems like the part is being operated in SCP just because of the current limit of 500mA. Of course, the resistive load will only see 500mA, but the tablet PC should definitely see more than 500mA.

The datasheet shows that there is a two step process for negotiation between the portable device and the TPS2540. So how does the PC connected to J2 interaction within this negotiation process to know what current limit should be set? Woudl the data line voltage levels correspond to this? Also, if there is addition power available at J1, how does that affect how much current is present to the portable devices.

What wuold you recommend on determining if the TPS2540is running in CDP mode? Checking the D+ and D- lines for the correct voltages during the negotiation process?

  • 0
    TI__Prodigy 650 points

    David,

    In order to support CDP fast charge, the portable device also needs to support CDP mode, otherwise it will be 500mA same with SDP mode.

    Very likely your device tested under CDP mode doesn't support CDP fast charge.

    For example, iPhone5/5S support CDP fast charge 1A, but older generation iPhone4/4S/3/3GS only do 500mA charge under CDP.

    Also, here are some popular new devices supporting CDP fast charge:

    iPad4, 1.4A; iPad Mini 1.3A; Galaxy SIII/S4 900mA; Nokia N8 800mA; Sony PSVita 1A......

  • 0 in reply to Vincent Wang64858
    Prodigy 60 points
    Hi,

    How can we find informations about tablets supporting CDP fast charge ?
    I try with Samsung galaxy tab 4 10" and it doesnt work. Can problem comes from this tablet which may be uncompatible with CDP fast charge ?

    Thanks,
  • 0 in reply to Yohan VERGNE
    TI__Prodigy 650 points

    Hi Yohan,

    We haven't tested Galaxy Tab 4 10" yet? Can you specify Galaxy Tab 4 10" not working? Is it not charging or not able to do data communication neither?

    To support CDP fast charging, both Host and Device side need to support CDP mode.

    For Tablets which can supprot CDP, the data we have on hand:

    iPad Air 1.4A, iPad4 1.4A, iPad Mini 1.3A, Galaxy Note 8.0" 1A, Galaxy Tab 3 7.0" 1A, Kindle Fire HD 0.9A....

    To test whether Tablet support CDP mode, best way is to test D+/D- handshaking when tablet plug in and check whether it can do CDP handsshaking properly and measure charging current to know whether it's doing fast charging.

     

     

  • 0 in reply to Vincent Wang64858
    Prodigy 60 points
    I am using TPS2540EVM-623 between my board and galatxy tab 4. My board has FT311D implemented for USB host side. Power provided to USB port can give current up to 3A.
    When i put the TPS2549EVM in CDP mode and plug galaxy tab 4 10" on USB, i have 950mA charging for about 2 second and then back to 500mA.

    I have data communication but not enough charging current.

    How can i " test D+/D- handshaking when tablet plug in and check whether it can do CDP handsshaking properly" ?

    Thanks,

    Yohan