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TPS659039-Q1: power sequency

Intellectual 1420 points
Dongbao Zhou

Part Number: TPS659039-Q1

Hi team,

My customer has some questions about the power sequence of tps659039, please help check:

1. Xi-osc0 powers up 6.6ms ahead of vddshv8, which is different from the required power sequence? Is there any risk and how to improve? 

2. Similar issue for vdda-rtc and vdda-abe-per, the actual test show that vdda-abe-per is 0.58ms ahead of vdda-rtc.

OTP version is O9039A387IZWSRQ1. Thanks

Dongbao

Intellectual 1420 points
Dongbao Zhou
  • Expert 4870 points
    Krishnamurthy Hegde
    Hi,

    I have assigned your request to responsible Applications Engineer and we will get back to you as soon as possible.

    Regards,

    Murthy
  • Intellectual 1420 points
    Dongbao Zhou
    Another quesiton is, is there any requirement for the power supply sequence of tps659039? 5V is used to power LDO7_LDOUSB_IN, LDOUSB_IN2 and LDO12_IN, 3.3V is used to power the rest LDO and buck. Any timing requirement for 5V and 3.3V?
  • Expert 3520 points
    Nastasha

    In reply to Dongbao Zhou:

    Dongbao,

    Hi, hope you are doing well. The 5V and 3.3V supplies should be high before the power sequence starts. It does not matter in which order they come up. If they don't come up before the power sequences begins, the SMPS and LDO rails may show a false short-circuit detection.

    On your sequencing questions, I think you are referring to the VRTC of the TPS659039-Q1? This rail is always-on and expected to be high ~6ms before the OTP power sequence begins. If the customer is following the platform connection of the TPS659039-Q1 to the AM57xx processor, there should not be any issues with the power up sequence timing. (User Guide: www.ti.com/.../swcu175c.pdf)

    Please let me know if this answers your questions.

    Thanks,
    Nastasha
  • Intellectual 1420 points
    Dongbao Zhou

    In reply to Nastasha:

    Hi Nastasha,

    Thanks for your reply.

    I just upload the wrong one for the first picture, i am sure they follow the recommendation, and it has no problem for the processor. However, the test results have some difference.

    Dongbao

  • Expert 3520 points
    Nastasha

    In reply to Dongbao Zhou:

    Dongbao,

    I am not sure which processor the customer is using so I do not know if there is any risk here. Can you ask this question on the processor forum? The processor team will have better understanding of whether there is risk to the processor. Please let me know if you have any PMIC concerns. If not, I will close this thread.

    Thanks,
    Nastasha
  • Prodigy 120 points
    FENG XIAOYU

    In reply to Nastasha:

    As described in the DATASHEET:  xi_osc0 can be turned off anytime after porz assertion and must be turned off before vdda_osc voltage rail is shutdown

    The crystal signal xi_osc0 is controlled by the PMIC input power supply vdda_osc,   but as the power-up sequence in DATASHEET，xi_osc0 is delayed after a long time after vdda_osc is turned on.

    Our measured results are the same, so we want to know if it is necessary to design consistent with DATASHEET?

  • Expert 3520 points
    Nastasha

    In reply to FENG XIAOYU:

    Feng,

    This is not part of the TPS659039-Q1 datasheet. I am moving this thread to the processor forum.

    Thanks,

    Nastasha

  • Genius 10900 points
    Stanislav Stilyanov

    In reply to FENG XIAOYU:

    Hi Feng,
    Think of the moment when clock starts on the diagram as the last moment allowed. Earlier start is allowed provided vdda_osc is present at that time. The PMIC should be already handling this.
    If clock is via crystal on XO and XI pins, then user cannot control clock start either.
    At last but not least, let's don't forget that clock oscillators need some time to stabilize at the required frequency, they don't start instantly.

    Regards,
    Stan

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