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LMX2485E Reset modulator

Carlos Casanova
Prodigy 235 points
Other Parts Discussed in Thread: LMX2485E, CODELOADER

Hi all,

In the app note AN-1879 (www.ti.com/.../snaa062a.pdf) (page 26,  part 4.3.3 Delta Sigma Sub Fractional Spurs), explains that the best method to avoid suubfractional spurs in LMX2485E is a reset modulator before write the modulator order.

How is the process to do this? Can you explain me the sequence of write registers?.

Thanks in advance.

  • 0
    TI__Expert 4085 points

    Hi Carlos,

    Are you familiar with Code Loader? It's the software used to program this device

    If you have it installed you should click on Select Device and select LMX2485E.

    If you go into the Bits/Pins tab you can see the option to Reset the modulator (shown in image below). After you reset you should select the modulator order.

    You can export register settings from codeloader in the "Registers Tab".

    The register settings can be found on the LMX2485E Datasheet on table 28 on page 30.

    It is Register 4 bits 15&14

    00=4th order modulator

    01=Reset modulator

    10=  2nd order modulator

    11= 3rd order modulator

    Example
    R4 0x204549  (Reset modulator)

    R4 0x20C549 ( select order, 3rd order in this case)

    Hope this helps!

    Best Regards,

    Julian

    If my post answers your question, please click on "Verify Answer" button.

  • 0 in reply to Julian Di Matteo
    TI__Expert 4085 points

    Hi Carlos,

    Don't forget to check the LMX2485 User's Guide for more information to get started with the software and with the EVM if you have one.

    Thanks,

    Julian

    If my post answers your question, please click on "Verify Answer" button.