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TPS65982 PPHV question in different FW version

Gary Teng
Genius 5860 points
Other Parts Discussed in Thread: TPS65982-EVM, TPS65982

Hi all,

 My customer us 12V/3A input througn PPHV path. Their final PCB have a problem in 12V application:

1. When using V1.5  FW, their VBus  can't output 12V. It drop to 0V after 5V. But if we setup the current as 0.5A/200% OVP, it will work.

2. When using V1.7 FW, Vbus can output 12V/3A correctly.

3. When using TI's dock reference design board, it works correctly by using V1.5 and V1.7 FW.

 Customer can't use V1.7 FW because they're required to support chromebook... Is anyone have idea about the question? Any external HW setting might cause the issue? I monitor the PPHV 12V input and it's fine in cc communication period and no voltage drop is found...

 Thanks for your kindly help.

Gary Teng 

  • 0
    TI__Mastermind 30310 points

    Gary,

    Please provide a little more detail on test procedure.

    When you say FW version can't output 12V, what are you using to test this? A TPS65982-EVM that will accept a 12V PD contract? An Ellisys PD Examiner/Analyzer?

    Which FW version have been tested with the ChromeBook and what are your results?

    Scope plots would be appreciated.

    We do have an understanding of the issue, but I want more info from you to ensure my understanding is the same as your test results.

    My understanding of the situation is as follows:

    • v1.5 FW performs a "break-before-make" connection when switching from PP_5V0 to PP_HV
      • This FW may support the Google ChromeBook, but
      • This FW will not be good for USB-C/PD Compliance testing
    • v1.7 FW performs a "make-before-break" connection when switching from PP_5V0 to PP_HV which utilizes the Reverse-Current Protection feature of the TPS65982 to protect PP_5V0 during the transition
      • This FW will pass USB-C/PD Compliance testing
      • This FW may not support 12V charging of the Google ChromeBook

    Although you may not see a voltage drop on VBUS during the transition, the Google ChromeBook is pulling too much current during a time called "Sink Standby", which results in the TPS65982 causing a PD Reset because the Google ChromeBook is not compliant with the USB PD spec.

    After careful consideration, we are temporarily deciding not to include a workaround to support the Google ChromeBook for safety reasons, because the only workaround would be disabling Over-Current Protection (OCP) during a critical transition window where a true short between VBUS & GND at the Type-C connector would cause damage to systems.

    Do you have an Apple MacBook with Type-C port that can use for your testing? The MacBook is compliant with the USB PD spec and will also charge at 12V.

  • 0 in reply to Brian Berner
    Genius 5860 points

    Hi Brian,

     1. I modify the flash setting in TPS65982 EVM as a 12V target by using V1.7.0 FW. I don't use Chromebook now. All boards in my place (TPS65982 EVM, 65982 dock board, and another customer board by using tps65986) can accept the 12V target.

     2. Customer's board use V1.5 FW (for supporting chromebook). I put the same code on tps65982 dock board as reference. 5V (through pp5V) and 20V (through PPEXT) works good. But when testing 12V (through PPHV), customer's board is failed. The VBus drop to 0V after 5V PD communication.

     3. Customer board with V1.5 FW, target use V1.76 FW, the VBus result is 5V and it doesn't drop to 0V...

     4. Customer board with V1.7 FW, it success in 12V communication / voltage output.

     I can pass customer's schematic to you if necessary. Please share me your mail address if you're interesting in it. Certainly, I can't fine any abnormal in their design...

     Thanks for your kindly help.

    Best regards,

    Gary