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TPS3703: The part stays in Reset

Part Number: TPS3703

Hi,

I am using TPS3703A5180DSER as power monitoring. See the schematics below

 connected the VSENS directly to a 1.8V (Measured as 1.807 from pin 1 to pin 5).

VDD is 5.1V and MR is measured as 5.1V.

Still the RESET output remains on "0". I disconnected R112.

What I missed?

Thanks

Noam

  • Hi Noam,

    I don't see any glaring issues with your schematic.  Is it possible to have you take some scope photos?  Also, can you connect the SENSE pin to a DC supply and vary the voltage?

    Ben

  • Hi Ben,

    Yes I did. The reset goes high around 1.1V. (In more than one board)

    Did I assemble the wrong part? How can I tell?

    On the part's package I saw the letters "JT" which seems the one that symbols 1.8V. I couldn't find the package letters for 1.1V.

    Noam

  • Hi Noam,

    According to TI's packaging part markup lookup tool, you have the correct part.  

    https://www.ti.com/packaging/docs/partlookup.tsp#divline

    All you have to do is type "JT" in the search phase.

    I have a few questions for you:

    1. Can you take a photo of a unit from that reel and the reel label?
    2. Were the units bought directly from TI?
    3. If no, were the units bought from a TI Authorized Distributor?
    4. Please provide the info of the distributor used.
    5. Is this a new application or an existing application?  If this is an existing application, were the previous units working? 

    Ben

  • Ben Hi,

    A lot of holydays this month so it took awhile. Attached is the pack picture.

    Noam

  • Hi Noam,

    I have passed your picture to the Quality and Reliability group for confirmation.  I will follow up with you once I hear back from them.  THanks!

    Ben

  • Hi Noam,

    A few more questions.  Can you tell me how much was purchased and did you directly purchased the parts from TI?

    Here is the feedback I received from the Quality and Reliability group:

    • Can a detailed description of the failure be provided?
    • What’s the customer reported failure rate (# devices failing/# devices tested)?
    • Can the customer provide any tracking information regarding the reported failure(s) (Date Code, LTC, STC, picture of the reel label the failure came from, etc.)?
    • Was an A-B-A swap performed (replace failing part with a known good part, place failing part on a known good board, etc.)? Does the failure follow the device or does it only occur on particular boards?
    • Can a customer schematic be provided?
    • What are the test/environment conditions when the failure is observed?
      • Pin biasing and sequencing conditions
        • Vin
        • Load
      • Environment conditions
        • Failing Temp (room, hot, cold temp?)
        • Humidity (if applicable)
      • Was an FAE involved to verify this complaint?
        • If so, please provide full detail of all the tests performed with results/waveforms.

    Can you provide answers to the questions above?

    Ben

  • Ben HI,

    I tried the following:

    1. Use a resistor divider to dived Vin to 1.8V. Reset remains asserted.

    2. Connect a 1.8V directly from a PMIC output. Reset remains asserted.

    3. Use a power supply to vary the SENS voltage. Reset de-asserted at ~ 1.1V.

    4. Connect 1.1V directly from a PMIC output. Reset remains De-asserted.

    We assembled 6 boards. So far we tested two and both showed the same behavior.

    All the tracking information is on the picture I sent. We bought it from Arrow.

    Schematic was provided in previous email. 

    No swapping was done. We are in the bring up phase.

    Room temperature, Vin=5.1V, no load (Reset signal is not connected).

    No one from TI was involved so far.

    Noam

  • Hi Noam,

    Can you try the other board?  If the other boards show the same behavior, it could be the parts are not advertised as 1.8V threshold variant.  Also, can you swap parts to see if it just those parts are no good?  At this time, I don't have much of an answer to give since the information you have provided have been very helpful in determining that the parts should be the 1.8V threshold variant.

    Ben

  • Hi Noam,

    If you have the opportunity, can you swap parts to see if the problem persist on another board?  If you can do an A-B-A part swap to confirm the failure follows the part.  This is done by replacing the failing unit with a known good part and placing the failing part on a known good board, etc. Does the failure follow the device or does it only occur on particular boards?

    Ben

  • Ben Hi,

    After doing some investigation it turn out that the parts arrived as samples from TI. See attached.

    I did the test for the rest of the units and it is all the same (Six out of six).

    Noam

  • Hi Noam,

    My suggestion is to contact your local TI representative and ask how you can get these units examine or have a failure analysis (FA) done on these units.  Maybe contacting customer returns?

    https://www.ti.com/support-quality/additional-information/customer-returns.html?keyMatch=PRODUCT%20RETURNS

    Ben