• State Resolved
  • Locked Locked
  • Replies 5 replies
  • Subscribers 63 subscribers
  • Views 517 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TPS73133DBVR Failure

Andrew Swanton
Prodigy 80 points

I am seeing a failure with my 3.3V LDO regulator. I am using the TI TPS73133DBVR and on four prtotyple boards out of 20 the regulator does not regulate it's output.

The input voltage is normally 5V and I have not been able to obseve any over or undershoot on that rail on stuartup or shutdown. Current draw is normally ~75mA which is well within spec of the part

On the damaged regulators if the input voltage is above 1.4V the output is equal to the input no matter wha the input volatge is. This leads me to belive that the feedback loop some how has been damaged. I did notice that I get 170mV on the NR pin of the regulator as opposed to the 1.2V I would expect which could mean the bandgap reference is somehow damaged.

I have a 100nF 0603 cermic capactor on the NR pin would there be any problems with that value of capacitor? What other things could cause such a failure?

  • 0
    TI__Expert 3300 points

    Hello Andrew,

    Thank you for your post. Can you please share the following information:

    What is the temperature you were operating the LDO's before you noticed the failures?

    Can you please share your schematic for the part where the LDO is employed? 

    What is the source of the 5V input to the LDO?

    Do you think an ESD event could have triggered the failures?

    Regards,

    Kartik

  • 0 in reply to Kartik Sinha
    Prodigy 80 points

    Hello Kartik,

    The LDOs were operating at room temperature before the failure.

    Here is a picture of the LDO circuit:

     

     

    The 5V is supplied by an MC34063 Buck Regulatoe

    I thought about ESD but since we have had 4 failures I find that it's probably unlikley as we have pretty good ESD control in our lab.

     

    Let me know if you need anything else.

    Thank you,

    Andrew

     

     

  • 0 in reply to Andrew Swanton
    TI__Expert 3300 points

    Hi Andrew,

    It is not clear as to why these parts failed. Can you send them in for Failure Analysis?

    Regards,

    Kartik

  • 0 in reply to Kartik Sinha
    Prodigy 80 points

    Hi Kartik,

    Sure I can do that.

    Can you send me the contact info for where to send the parts for failure analysis?

    Thanks,

    Andrew

  • 0 in reply to Andrew Swanton
    TI__Expert 3300 points

    Hi Andrew,

    Please fill up the attached form and mention the following information in the 'description' section:

    1. Detailed information about the failure. What’s specifically is failing with the device? Low output voltage? Device not enabling correctly? Please be specific.
    2. What is the failure rate that the customer is seeing? How many devices are failing out of how many used in production?
    3. Can any tracking information be provided about the failures? Ship Trace Codes (STC), Lot trace codes (LTC), Assembly lot #s, etc.? Can the customer provide a picture of the reel label(s) that they are seeing failures from?
    4. Provide the operating conditions of the failure (temperature, pin biasing conditions, etc.)
    5. Can an application schematic be provided? This will help the Verification team in Dallas duplicate the customer set-up conditions on the bench.
    6. Does the customer have any waveform captures of the failure?

    The shipping instructions and address are provided in the attachement as well. Thanks

    Regards,

    Kartik

    5488.TI FA Request Form (HPA and PWR Rev- 0).docx