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TPS2546: TPS2546 USB certification issue

AJ Cheng
Genius 3615 points
Part Number: TPS2546
Other Parts Discussed in Thread: TPS2547, , TPS2549

Hi 

My customer used  TPS2546 can not pass the USB certification. We got fail about A4.9: Host Test J/K, SE0_NAK (EL_9) in SDP / CDP mode.

SDP mode Test K in D+ is over 20mV and D- is pass. CDP mode Test J in D- is over 20mV and D+ is pass. Do you have any suggestions? Thanks for help~

  • 0
    TI__Expert 5110 points
    AJ,

    Could you share the schematic for the design so that our team can review and provide you input on this certification failure?

    Regards,
    Atiq
  • 0 in reply to Atiq Rahman
    Genius 3615 points

    Dear Atiq.

    Please reference on below and thanks for kindly help~

  • 0 in reply to Atiq Rahman
    Genius 3615 points

    Dear Atiq.

    Update more. Thanks~

  • 0 in reply to AJ Cheng
    TI__Intellectual 1960 points
    has the voltage been measured on DM_OUT and DP_OUT pins when the test fails? Please also confim the mode the device is in when the test fails(CTL* mode level)
  • 0 in reply to Yoon Lee
    Genius 3615 points

    Dear Yoon.

    When test fail the DM_OUT is 24~27mV and DP_OUT about 400mV. Test is in CDP mode.

    We change TPS2546 to TPS2547 also got fail. Please kindly help it.~

  • 0 in reply to AJ Cheng
    TI__Intellectual 1960 points
    Hi AJ, I think it may be the USB host/hub controller contributing to the offset. Could you check the DM_OUT and DP_OUT voltage, DM_IN and DP_IN while EN = low. This should disable the signal switch. If offset voltage measured on DM_OUT and DP_OUT while EN = low, the offset may be driven by the USB host/hub controller.
  • 0 in reply to Yoon Lee
    Prodigy 20 points

    Dear Yoon,

    We test as below, if need any more information, please let me know, thanks! 

    While EN = low.
    DM_OUT=5.177V
    DP_OUT=4.084V
    DM_IN=27mV
    DP_IN=21mV
    While EN = low, under Test J condition.
    DM_OUT=5.177V
    DP_OUT=3.089V
    DM_IN=31mV
    DP_IN=24mV
  • 0 in reply to Jerry Chang
    TI__Intellectual 1960 points

    Just to confirm, non driven signal lines(D+ or D-) need to be below +/-10mV to pass when measured at the connector, correct?

    What is the measurement condition?  WIth the sQuidd board attached?  Are DM_IN and DP_INs connected to the connector?  What is the connection between DP1L/DM1L and DP1L_C/DM1L_C?

    DM_OUT/DP_OUT connected to the host controller?

  • 0 in reply to Jerry Chang
    TI__Intellectual 2685 points

    Hi,

    ‘The issue is due to a conflict between the Test_J and the BC1.2 Spec. 

    Test_J places a 400mV DC signal on the D+ line.  This happens to be within the window where the BC1.2 spec defines primary detection.

    Thus, the TPS2546 sees a primary detection voltage on D+ and since the TPS2546 is in CDP mode, it responds by putting VDM_SRC on D-. 

    In a normal CDP situation the D- voltage would be around 0.6V.  But this is not a normal situation since the D- line is loaded with two 45 ohm resistors in parallel for a total D- resistance to ground of 22.5 ohms. 

    The maximum D- load in primary detection is 250uA.  Meanwhile, 0.6V into 22.5 ohms is over 25mA. 

    So the Test_J  is both triggering primary detection and placing a short circuit on D-.  Now the TPS2546 is designed to protect against a primary detection short and has a 1mA (typ) current limit on the D- output. 

    So now we can see that a 1mA current limit into a 22.5 ohm load will obtain the 22mV voltage on D-.

    This issue only occurs when a Test J packet is sent on a CDP with a standalone battery charging device(TPS2546 in this case), not a real world condition hence does not have impact on real application.

  • 0 in reply to Yongqiang Sun
    Prodigy 20 points
    Hi Yongqiang Sun,
    Thanks for your reply.
    Cause our product need to pass USB certification, please let me know how to explain Allion Lab cause they follow USB-IF's requirement, any method to pass/waive the Test_J?
  • 0 in reply to Jerry Chang
    Genius 3615 points
    Dear Yongqiang .
    Do you have any suggestion? We need your help. Thanks~
  • 0 in reply to Jerry Chang
    TI__Intellectual 2685 points

    Hi,

    if passing the Test-J is mandatory, I think customer will have to change to TPS2549, TPS2549 can pass the test-J.   we have a detailed report, please send me an email and I will share the report with you.  yongqiang-sun@ti.com