• State Resolved
  • Locked Locked
  • Replies 3 replies
  • Subscribers 22 subscribers
  • Views 734 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.

LMX2594: LMX2594

shen jie
Intellectual 305 points
Part Number: LMX2594
Other Parts Discussed in Thread: TIDA-01021, LMK61E2, LMK00304

Hi, 

I have a question about LMX2594. My setup is listed below which refer to TIDA-01021 design :

1. LMK61E2 output 100MHz to OSCin of  LMK04828B 

2. OSCout of  LMK04828B ouput 100MHz to the buffer(LMK00304)

3. The buffer output 100MHz(Lvpecl) to the LMX2594

But, the Lock status([10:9], rb_LD_VTUNE) always toggle between lock(0x2) and unlock(0x3) as below figure shown:

My question: which reason will impact the Lock status of LMX2594? component selection for loop filter?

Below figure is my loop filter for LMX 2594. 

Best regards!!!

Jason

  • 0
    Intellectual 305 points

    BTW, some information need to be added:

    1. the LMK 04828B work as single-PLL mode correctly, which just serve as buffer for LMK61E2. 

    2. The LMX2594 is configured as below figure shown:

  • +1 in reply to shen jie
    TI__Guru** 111720 points

    Hi Shen Jie,

    If you set MUXout = lock detect output, is the signal output also toggling between HIGH and LOW? Is the RF output from LMX2594 really lock?

    Did you check the 100MHz clock after the buffer LMK00304?

  • 0 in reply to Noel Fung
    Intellectual 305 points

    Hi, Noel Fung:

    I have found the root cause for unlock issue of lmx2594. The capacity of C2_LF on my schematic is too small( 1.8nF) which cause the unlock of LMX2594.

    So, the register ([10:9], rb_LD_VTUNE) could indicate the lock status of lmx2594 effectively. No need to set MUXout = lock detect output

    Thank you very much!

    Best regards!

    Jason