• State
  • Locked Locked
  • Replies 7 replies
  • Subscribers 63 subscribers
  • Views 672 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.

LM5017 Unexplained failure

Andrew Meikle
Prodigy 90 points
Other Parts Discussed in Thread: LM5017

I have had some LM5017 regulators fail.

What I found is that they worked fine, then when powered off it would not restart.

I replaced the LM5017 and it powered up perfectly.

There is no physical damage to the LM5017

I did notice that the inductor was warm after it failed.

 

Please can you check if there is a configuration problem, or a bad batch and advise why these units have failed.

My settings are as follows:

  • 0
    Prodigy 90 points

    Here is a bit more information.

    Vin ranges from 40 - 90 volts

    current and voltage output is around 30ma @10.15v

    when it failed the input was at a constant 60v on a lab psu

    I have ruled out the start-up regulator, because VCC is still outputting 7.6v

  • 0 in reply to Andrew Meikle
    TI__Genius 11490 points

    Hi Andrew,

    How do you turn off the regulator, using UVLO or VIN?

    Is the failure repeatable? Did you observe the inductor current/switch node when part was turned off/on?

     

    Thanks an dregards,

    Vijay

  • 0 in reply to Vijay86929
    Prodigy 90 points

    Hi Vijay

    The main power feed is shut down, so VIN should shut down the regulator.

    It dose have a input capacitor, so it is possible that as the voltage collapses UVLO shuts off the regulator first.

    I can raise the level of UVLO to 25v so that it would cut out sooner as the voltage collapses.  

    No it is not repeatable. I haven't looked at the inductor current when turned off, the load was minimal at around 30ma on the output.

    Is it possible that the moisture sensitivity of the S08 device could cause this type or failure?  

    I do not know how they were handled at the factory.

    Regards

    Andrew

  • 0 in reply to Andrew Meikle
    TI__Genius 11490 points

    Hi Andrew,

    If VIN is down the output capacitor will discharge through the body diode of the buck FET to VIN. If COUT was really big this may heat up the inductor, as you have observed, and possibly stress the FET. But the COUT is not that big in your application.

    It is difficult for me to comment on the reason of failure if it is not repeatable & without looking at any waveforms. You can submit the failed devices through your local TI sales channel for failure analysis.

    Regards,

    Vijay

  • 0 in reply to Vijay86929
    TI__Genius 11490 points

    BTW I should have asked earlier. Are you working with a demo board or is it your own board?

  • 0 in reply to Vijay86929
    Prodigy 90 points

    Yes I can submit the failed device. Please advise where to mail it, and I will send it off right away.

    I am working on my own production board.

  • 0 in reply to Andrew Meikle
    TI__Genius 11490 points

    Hi Andrew,

    The FA is submitted your local sales contact.

    Regards,