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TPS65911: PMIC won't start and input voltages look correct, TPS659112

Stephen Hicks
Intellectual 470 points
Part Number: TPS65911

I have a TPS659112 on a new design PCB.  I have verified the following things:

  1. VCC7 = 6.3V
  2. VCCS = 3.56V
  3. VRTC = 18.V
  4. VCCIO = 5.34V

I have grounded VBACKUP which may or may not be the proper thing to do.  I can see a 32kHz oscillator input on OSC32KIN (which I believe is not required since it has the RC oscillator internally).  I do not see output on CLK32KOUT, however.

My expectation is that the PMIC would autostart, but it does not appear to be doing so -- the outputs of other regulators I've checked to not appear to be on.  VDDIO, for example, has 20mV or so on it.  Control pin schematic below:

Any ideas why the part will not autostart?

  • 0
    Intellectual 470 points
    Apparently, the 5V supply was going back off promptly and this was the issue. So I've moved past this problem.
  • 0 in reply to Stephen Hicks
    TI__Genius 17380 points
    Thank you for the update Stephen, let us know if you run into any other issues.
  • 0 in reply to Kevin LaRosa
    Prodigy 75 points

    Kevin,

    I am working with Steve on this problem.  While the voltages are correct now, we are seeing the TPS659112 go into a looping reset exactly as described in this post: .  

    e2e.ti.com/.../1166774

    This post refers to a calculator for the parts but we cannot find anything in the thread or one the website to calculate the component values.  I am especially concerned about the value of Rtrip.  There is no information in the datasheet about how to calculate the value of Rtrip.  This post was never marked as solved.

    We have confirmed that the AVS supply on VDDCtrl is causing the shutdown by removing C426 on the input of the supply.  This stopped the oscillating reset.   However this means there is no AVS supply for the DM8168.  Can you supply the calculator for this part?  Can you suggest what to do next in diagnosis?

    Thanks,

    Gerald

  • 0 in reply to Gerald Youngblood60
    TI__Genius 17380 points
    Hi Gerald,

    I found the calculator for TPS659110 OTP on our internal drive and it is labeled as NDA Confidential. Do you have local TI sales contact to coordinate? They typically set up NDA and provide any material under NDA.

    Other than that I will defer technical support to Rick on the other forum post as he is more familiar with this device than I am.
  • 0 in reply to Kevin LaRosa
    Prodigy 75 points

    Kevin,

    Thanks for asking.

    Unfortunately TI has stopped direct support and support through distribution for all but their very largest customers.  We used to have great local support but that has gone away.  We can no longer get support though Avnet or Arrow either.  We had an NDA in place from a couple years ago and were getting regular briefings then.  

    Maybe Rick can provide the calculator.  It's hard to use a part without appropriate documentation and tools.  There is no information in the datasheet or on the website on how to calculate Rtrip for example.

    Thanks,

    Gerald

  • 0 in reply to Gerald Youngblood60
    TI__Genius 17380 points
    Hi Gerald,

    I'll follow up with you via email for now to get you helped out.
  • 0 in reply to Kevin LaRosa
    TI__Expert 3395 points

    Hi Kevin, I have another customer with the same issue.  Are we able to document a solution publically?

  • 0 in reply to Will Jarrett
    TI__Genius 10000 points

    Jarrett,

    We do not have this document publicly published yet. If you need this document now, please contact your local sales representative to receive this under NDA.

    Thanks,
    Nastasha