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Original question:

TPS2546: Cannot support Apple iPhone 5 or iPhone X changing during S3 when "USB Legacy Port Charging" = disable?

TPS2546: Cannot support Apple iPhone 5 or iPhone X changing during S3 when disable "Always On USB" on lenovo laptops

Feng Gao47
Prodigy 20 points
Part Number: TPS2546

Dear TIs

I have the following question can you help me analyze it?

Lenovo laptops have a feature named "Always On USB", when disable "Always On USB"(this settings can change in bios) TPS2546 will set the charge mode as SDP mode,we also found Apple iPhone 5 or iPhone X changing during S3 when disable "Always On USB",others andriod phone like huawei,xiaomi,etc can charge during S3 when disable "Always On USB",but we also found some special phone like lenovo ZUK Z2' charge behavior is same as iphone during S3 when disable "Always On USB",can you analyze this problem,

  • 0
    TI__Mastermind 30000 points
    Hello Feng,

    Thank you for posting your question here on E2E

    1. I am confused as to what your question is. In your description, you mention when "USB legacy port charging = disable". What do you mean by this? The TPS2546 is designed for BC1.2 which is used in legacy devices so this is not a mode within the part.

    2. In the title, you say "iPhone X changing". DO you mean iPhone X charging?

    3. What is the issue that you are seeing? Some of the phones you mentioned cannot charge when the TPS2546 is in SDP mode, S3 power state?
  • 0 in reply to Adam Mc Gaffin
    Prodigy 20 points

    hi Adam

    Question 1：

    What I mean is Lenovo laptops have a feature named "Always On USB", laptop have a port  with TPS2546 embedded that can supply max 2.1A current，but when disable "Always On USB"  function and then system enter S3（S3 means sleep the system），the USB port max current is 500mA for USB2.0 port. USB 3.1 Gen 1 port max allowable current is 900mA，this moment TPS2546 will set the USB charge mode as SDP mode，in this state，we find apple phone can not charge when system enter S3，others andriod phone that is to say BC1.2 devices  can  charge，I don't quite understand why?

    Questions 2：

    Yes
    Question3：

    we try to use amperemeter to measure apple and BC1.2 current in above state,apple have a current of 0.08A,BC1.2 phone have a current of 0.45A，but apple system battery icon don't display charge,BC1.2 phone battery icon can display 

    I'm sorry,since I'm not very professional, I can only describe what I see.

  • 0 in reply to Feng Gao47
    TI__Mastermind 30000 points
    Hello Feng,

    I understand your question now, thank you for the clarification.

    When the device is in power state S3, does it matter if the data lines are connected or not? I was able to replicate the issue with the TPS2546EVM that you are seeing when the part is in the S3 power state and SDP mode. I was not able to charge my phone either. However, I tried when the device is in DCP_Auto and the TPS2546 was able to charge the iPhone without problem.

    Also, after talking with a colleague, we believe that the issue is within the iPhone itself, not the TPS2546. In SDP mode, the TPS2546 and all other source devices just pass through the D+ and D- lines and does not send any response signals. The portable device, in this case an iPhone, is the one that draws the current from the source as VBUS is always on. Something must be happening internal to the iPhone that does not have it sink up to this device.

    Since this problem is within the iPhone itself, this problem is the same for al the TS254x family of devices.