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LMX2572: LMX2572 locked at low temperature okay. However reloading the registers with the same data at low temperature may cause and unlock condition.

Stuart Rumley
Prodigy 250 points
Part Number: LMX2572

Tool/software:

LMX2572 running okay at low temperature of about 0deg C and locked.  If I reload the registers at this lower temperature, the LMX2572 may not always lock.  When taken back up to normal temperature then reloading registers does not cause a problem and it locks okay.  The serial data looks the same.  Seems to be a low temperature related issue with loading registers and getting a lock.

  • 0
    TI__Mastermind 18990 points

    Stuart,

    I have assigned someone to this post, please expect a response by Monday worst-case.

    Thanks,

    Kadeem

  • 0 in reply to Kadeem Samuel
    TI__Guru* 98080 points

    HI Stuart,

    Could you provide your configuration?

  • 0 in reply to Noel Fung
    Prodigy 250 points

    Noel,

    I have found cause of this low temperature reliability issue.  In this design I had used OSCinM for the single-ended reference signal assuming incorrectly that either OSCinP or OSCinM could be use for single-ended input.  Later in the design verification testing it was discovered that only OSCinP could be used as the SE input.  Since over 100 boards had been assembled, the fix for this error was to set OSC for differential mode but with only OSCinM supplied.  This actually worked ok until we started our environmental testing and discovered there were a number lock failures. 

    In order to fix this problem and still use the existing production boards, I was able to simply tie OSCinP to OSCinM and supply both with the reference signal but set the OSC input to single-ended.  So far so good.

    Thank you for getting back me,

    Stuart