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Problems with LMX2581 programming and application

Seweryn Krawiecki
Prodigy 10 points

Other Parts Discussed in Thread: LMX2581, CODELOADER

I have problem with LMX2581 programming by CodeLoader in version 4.7.5. I would like to ask about proper register map, because there are few mistakes, and I can`t program my IC correctly. DLD_TOL and FRAC_ORDER are longer than showed in register map on page 11 in data sheet. Second thing is inaccuracy in BUFEN_DIS bit and BUFEN pin collocation. I think that BUFEN_DIS should be rather 0 than 1 to ignored BUFEN_PIN to be consistent with table on page 8. I would like to know if there are much more mistakes in this data sheet or CodeLoader, because I have big problem with programming, simply this IC doesn`t work. There is no power at output. I would be grateful for any help.]

  • 0
    TI__Mastermind 28031 points

    Seweryn,

    1.  The most current datasheet is at http://www.ti.com/lit/ds/symlink/lmx2581.pdf and DOES show DLD_TOL and FRAC_ORDER.   This was updated in April and you should defilitely show this datasheet.

    2.  The BUFEN pin allows the user to turn the output on and off with a pin.  But more often than not, it is not used.  For these cases, setting BUFFEN_DIS = 1 ignores the pin, which is our default CodeLoader setting.  But if you are interested in using this pin, change the defailt.

    The problem is the table on page 8 (old datasheet) and page 9 (new datasheet) is wrong.  Setting BUFEN_DIS=1 should ignore the BUFEN pin.  The description for the BUFEN_DIS bit on page 18 of hte new datasheet is correct.

    3.   Aside from the above #2, which we will fix, there are no other known issues.  No power at the output could be caused by many things such as:

    a.    LMX2581 is running but output buffer is disabled.  In this case, there is an output, but it is on the order of -45 dBm or so.

    b.   LMX2581 is powered down, in this case, current consumption is low.

    c.   LMX2581 is running, but locked to a frequency other than where you are looking.

    4.   If you use codeloader, go to Help->About.  Program version is 4.7.5, but the part ini file version should be 4.18.2013.  If you go to Mode-> Default Mode-> Default Mode 4.18.2013, this will restore the original settings to which we have programmed and tested the board too.

     

    Regards,

    Dean

    1.