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TPS2543EVM Charging Current Limited at 500mA

Other Parts Discussed in Thread: TPS2543, TPS2546, TPS2511, TPS2514, TPS2513

We have the TPS2543EVM and we are using a bench power supply for the initial testing. We tried all modes and with 2 different cell phones but we are only seeing ~500mA of charge current. It seems like we must be missing something obvious as to why the current is not going above 500mA, but we haven't found it.

  • Could you double-check the mode settings v. Table 2 in the datasheet? Also, can you mention the cell phone model's checked? Remember that the cell phone must determine what it is connected to and then manage it's own current draw. The power switch current limit in TPS2543 while adjustable is not generally active until the load tries to exceed the set point.
  • Yes, in fact we tried almost all combinations of the mode settings. We started out testing with an older Samsung Galaxy SII which I believe should charge at the 1A rate. The 2nd phone we tried was the new One+ phone.

    We just tested with a Samsung Galaxy S4 and all modes and we are getting less than 500mA.

  • we did not have any test report data for the S II. And the newer phones might not work correctly with TPS2543. If you get the chance, please try TPS2546 as it is newer.
  • OK, we'll get some TPS2546 samples on order and test with that part. If we were to choose a dedicated charging part which of the TPS2511/13/14 parts would you recommend if we wanted to support the most products?
  • TPS2511 supports 5W and 10W Apple products as well as Samsung devices (and most older BC1.2 devices). TPS2511 has an integrated power switch and cable compensation (can adjust the dc/dc converter inpt upwards when power switch current crosses 0.5 x ILIM threshold). TPS2513/14/13A/14A do not contain the power switch. TPS2513/13A are dual port and TPS2514/14A are single port charging controllers. All support most BC1.2 devices and Samsung 1.2V devices. The non-A devices support Apple 5W and 10W devices while the "A" devices support only the 12W devices.
  • So it sounds like if we don't need the power switch the TPS2513/14 will support a wider range of products? It sounds as though I cannot support the full line of Apple products, I have to choose between supporting older generation the newer 12W devices? Are my assumptions correct?
  • Yes, you'v got it! Currently, the TPS2546 will support the highest amount of devices but there are new devices coming out so fast that it is impossible to keep up.
  • We got the TPS2546 samples in and built a board using this part. We tried this as an initial test:

    ILIM is high

    Enable is high

    CTL1 is low

    CTL2 is high

    CTL3 is high

    which should be "Dedicated charging port, auto-detect, with load detection enabled"

    We tried the Samsung Galaxy S2 and the new One+ and both only drew ~500mA. We then tried an Apple iphone4 and it only drew ~600mA

    There must be something we are missing which is limiting us from charging at higher levels but I can't see what!

  • Could you post the test wave including the VBUS, D+, D-? Additionally, make sure used the OEM cable and please adjust the VBUS to 5.15V to do the test.
  • The devices seem to be extremely sensitive to the level of Vbus. We had some loss in the cabling setup we were using so the voltage at the USB connector of the device was ~4.9V. We adjusted for the loss in the bench top power supply cabling and increased it until we measured 5.15V on the USB connector. We immediately saw an increase of current. Levels are still a little lower than I'd like to see but it's a major improvement right now.

    iPhone 4 draws close to 1A

    Samsung Galaxy S2 draws close to 1A

    LG G3 is close to 1A

    One+ One is only ~500mA

    iPad 3rd Gen is ~1.6A

    I would expect the LG and the iPad to pull over 2A though.

  • George,
    You got it again :), yes, portable device is very sensitive to Vbus droop, lower Vbus voltage, lower charging current.
    5.15V is the right level of Vbus you want to have in system, you can see iPhone4 and S2 are 1A which is same with OEM charger.
    For iPad 3, if you keep the display on and play some APPs especially video games, you can see the charging current up to 1.8A-2A.