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.

LMX2491: Device Usage Conditions

Part Number: LMX2491

Tool/software:

Hello,

My customer confirmed that PLL Lock is normal when REF=100MHz, PDF=1MHz, R=100 is set using the LMX2491 board they designed.

However, when REF=100MHz, PDF=100MHz, R=1 is set, PLL Lock is not worked.

Are there any issues with the above conditions under which they use the LMX2491?

Thank you.

JH

  • Hi JH,

    This is likely due to the loop filter is no longer valid at fpd = 100MHz. You have changed the fpd 100x , you should re-design the loop filter accordingly.