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TPS65381A-Q1: tps65381A-q1 reported ABIST failure

Benjamin Zhou
Expert 4000 points
Part Number: TPS65381A-Q1
Other Parts Discussed in Thread: TMS570LC4357, , TMS570LS1227

Hi Team, 

  My customer used TPS65381A-Q1 to provide power to TMS570LC4357,  the TPS65381A-Q1 reported ABIST failure in such condition:

  -Enabled Watchdog of TPS65381a, Powered on, TMS570LC4357 worked as normal, TPS65381A is in ACTIVE mode;

  -Using JTAG connected the LMC4357 to computer, stopped the software to feed the TPS65381a watchdog;

  -TPS65381A reseted, and switch from ACTIVE mode to SAFE states, then to RESET, and then to DIAGNOSTIC,  the ABIST failure reported.

  -Change the TMS570LC4357 to TMS570LS1227,  do the same procedure as previous description, no  ABIST failure reported.

Could you kindly give comments which will influence the ABIST failure while using TMS570LC4357? is it link to the power consumption of the controller or not? Expect for your comments, thanks.

Best Regards

Benjamin

  • 0
    TI__Genius 16410 points
    Hello Benjamin,

    I've assigned this post to the device expert, he will respond to your question.

    Regards,
    Karl
  • 0 in reply to Karl Wallinger
    TI__Mastermind 20590 points

    Hi Benjamin,

    It is most likely due the the JTAG debugging not being real time and the processor getting out of sync with the TPS65381A-Q1.  When this debugging is happening is the customers system forcing any of the voltage rails to be over current and causing an undervoltage when the TPS goes through RESET state to DIAGNOSTIC stste?

    Best regards,

    Scott

  • 0 in reply to Scott Monroe
    TI__Mastermind 20590 points
    Hi Benjamin,

    Please have the customer read the note in section 5.3.5 VSOUT1 Linear Regulator of the datasheet about possible cause of ABIST_ERR when the device goes through RESET state if there is a fault on VSOUT1 regulator when the ABIST is run.

    NOTE
    The VSOUT1_EN bit is in the SENS_CTRL register which is only reinitialized by a power-on
    reset (NPOR) event and not a transition through the RESET state. If the VSOUT1_EN bit
    was previously set to 1, it remains set to 1 and the VSOUT1 regulator remains enabled after
    events that cause a transition to the RESET state. In a fault case that would cause an
    undervoltage or overvoltage on the VSOUT1 pin, when a BIST runs automatically on the
    transition from the RESET to the DIAGNOSTIC state, the VSOUT1_UV or VSOUT1_OV
    condition during the BIST


    This or something similar with their non-real time running of the MCU with debugger and possibly other unexpected states on TPS65381A-Q1 pins or rails due to the debugging may be causing the ABIST_ERR detection when it is automatically run as the TPS transitions through RESET to DIAGNOSTIC state and the BIST is run.

    Best Regards,
    Scott
  • 0 in reply to Scott Monroe
    TI__Expert 4000 points
    Hi Scott,
    Has informed to customer for the Notes, and customer did some test that while change the TMS570LC4357 to TMS570LS1227, this ABIST Error is not happened, and also test the voltage for the 1.2V rail, it dropped to <1.1V, seems that TMS570LC4357 has triggered the undervoltage situation.

    Best Regards
    Benjamin
  • 0 in reply to Benjamin Zhou
    TI__Mastermind 20590 points
    Hi Benjamin,

    The VDD1 rail may need more output capacitance or better placement may be to add more input capacitance at the TMS570's to reduce the load step transients on the rail so the VDD1 will not go under voltage. It may also be a layout issue if the routing for this high current trace isn't done well.

    Scott