• State
  • Locked Locked
  • Replies 2 replies
  • Subscribers 21 subscribers
  • Views 303 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.

LMX2594EVM: defective, with instabilities and spurs?

Ion Prisecaru
Prodigy 30 points
Part Number: LMX2594EVM

New board LMX2594EVM (+ Ref board) was bought last month (less than 4 weeks ago).

Then last week I got my brand new 10MHz OXCO with 1ppb stability. Task of the board: output 10GHz.

In the evening was all beautiful, clean and stable. Exceptional everything, then power off.

Literally overnight, after power on, the board woke up unstable and full of spurs. Apparently all efforts to bring it back to clean results had no success.

I get a feeling that the Output power too, does not react identically as previously (before were tested with a 100ppb OXCO). Now the range of output power is only between -12dBm and -7dBm. Cannot be sure, this board is still "new" to me. Not fully familiarized with it. I did not thought of documenting the good results from the first day. Probably they were too good.

Any case, old or new OXCO, the spurs any instabilities were not there a week ago. Maybe... one spur in 15 minutes... but not 10 spurs per second as now.

Can I fix this myself or should I send the EVM board back for replacement?

What could have caused the issue?

Thanks,

  • 0
    TI__Guru** 108490 points

    Hi Ion,

    I don't know what was happening, maybe you can do some debug first. Please check, after Vcc is applied and before programming, can you see similar voltage on the following pins? What is the power consumption at this state?

    Pin

    Name

    CAP

    POR

    3

    VBIASVCO

    C25

    1.017

    27

    VBIASVCO2

    C19

    0.652

    29

    VREFVCO2

    C20

    2.856

    33

    VBIASVARAC

    C21

    1.609

    36

    VREFVCO

    C22

    2.85

    38

    VREGVCO

    C24

    2.03

  • 0 in reply to Noel Fung
    Prodigy 30 points

    Partial info: for the 3,3V supply for the board (after programming) the current was ca. 0.3A.

    The debug voltages I can read sometime soon and I will let you know if they match your chart.

    Thanks,