• State
  • Locked Locked
  • Replies 6 replies
  • Subscribers 47 subscribers
  • Views 780 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.

ADS7946: ADS7946 REF short to REFGND

vincent zhang22
Prodigy 10 points
Part Number: ADS7946
We are using ADS7946, and damaged, most of them are REF(pin3) short to REFGND(pin4)
schematic as attached file,
could you give me advice?
  • 0
    TI__Mastermind 25020 points
    Hello,
    Is the short within the device or on the board? In other words, when the part is removed from not board and not connected to anything, are the two pins shorted? Or, when the device is removed from the board, and a continuity test is done on the unpopulated board, the short is present?

    Giving your schematic a quick glace, it looks good.
    Regards, Cynthia
  • 0 in reply to Cynthia
    Prodigy 40 points
    when removed this ADS7946, and test this ADS7946, ref is short to refgnd
  • 0 in reply to Cynthia
    Prodigy 40 points
    Cynthia,
    thanks for your reply.
    Yes,when the part is removed from not board and not connected to anything, the two pins are shorted.
  • 0 in reply to wei zhao
    Prodigy 40 points
    Cynthia,
    is there any requirement of power on and power down sequence for this chip? AVDD,DVDD,REF
  • 0 in reply to Cynthia
    Prodigy 40 points

    Cynthia,
    is there any requirement of power on and power down sequence for this chip? AVDD,DVDD,REF

  • 0 in reply to wei zhao
    TI__Mastermind 25020 points
    It sounds like the devices are being damaged at some point during operation. I would suggest doing a continuity test on your board, just to make sure there are no issues there.
    Is it possible that the device is being exposed to higher voltage than rated for, or ESD exposure.
    The device does not have power up recommendation, since the AVDD and the DVDD can be independt from each other. it is good practice though to bring up AVDD before DVDD, but bring them up together is just as well. The reference is also independent from AVDD, but it is also good practice that AVDD come up first, or both come up togther.
    Do you have new parts that are not damaged? Perhaps one can be used to evalaute step by step your procress to see if/when the device is damaged.

    Regards
    Cynthia