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TPS65311-Q1: RESN @LPM0

Kuramochi Tadahiko
Guru 28715 points
Part Number: TPS65311-Q1

Hi,

How does the RESN behave when the TPS65311 moves into LPM0?

Does it keep High if there is not any reset condition?

Or does is the RESN goes low by detecting fall of each output voltage?

Best Regards,

Kuramochi

  • 0
    TI__Genius 16030 points
    Hi Kuramochi-san,

    I've assigned this post to the appropriate applications engineer, he will respond to your question.

    Regards,
    Karl
  • 0 in reply to Karl Wallinger
    TI__Expert 8730 points
    Hi Kuramochi-san,

    Based on my understanding, RESN will be low during the LPM0 mode. However, I have not measured the exact timing of LPM0 to RESN low. Currently i am out of office and I will get back to you on this by mid of next week.

    Regards,

    Murthy
  • 0 in reply to Krishnamurthy Hegde
    Guru 28715 points
    Murthy-san,

    Thank you for your information.

    I have two additional questions.

    - What is the trigger RESN goes low when LPM0?
    i.e.) detecting output voltage drops

    - Does the RESN keep low during LPM0?

    If you have a timing chart of RESN behavior during LPM0, can you share it?

    Best Regards,
    Kuramochi
  • 0 in reply to Kuramochi Tadahiko
    TI__Expert 8730 points
    Hi Kuramochi-san,

    RESN goes low as soon as SPI write for LPM0 is completed. I measured around 9us between CSN high to RESN low after writing LPM0 SPI command. It is not dependent on output voltage drops.

    RESN is low during LPM0 mode.

    Regards.

    Murthy
  • 0 in reply to Krishnamurthy Hegde
    Guru 28715 points
    Hi Murthy-san,

    Thank you for your help.

    I have an additional question.

    If the device moves into LPM0 mode and the WAKE pin is high, the device moves into ACTIVE mode via TESTSTART etc.
    Is it correct?
    If yes, how long is the RESN pin asserted to Low?
    Is it tWAKE-RES =14ms(max)?
    If yes, could you show me min/typ value for our reference?

    The customer is supposed that WDT gets wrong by runaway of MCU.

    Best Regards,
    Kuramochi
  • 0 in reply to Kuramochi Tadahiko
    TI__Expert 8730 points
    Hi Kuramochi-san,

    Your understanding about LPM0 to Teststart when Wake is high is correct. You are also correct regarding "tWAKE-RES" timing and in the worst case, RESN can be low for that time. Based on the bench measurements, I see that typically it takes around 7ms until RESN goes high after WAKE is detected. Exact minimum value is difficult to tell. I will send you an email and provide you an approximate number based on internal data.

    Regards,

    Murthy