• State TI Thinks Resolved
  • Locked Locked
  • Replies 1 reply
  • Answers 1 answer
  • Subscribers 20 subscribers
  • Views 426 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: Driving OSC pins differentialy with LVPECL

Izik
Expert 1585 points
Part Number: LMX2594
Other Parts Discussed in Thread: LMX2592

Hello 

I would like to use LMX2594 with 100MHz reference in LVPECL. The distance between the LVPECL driver to the OSC pin of LMX2594 can be 4-5 inch stripline. 

So I thought about placing two 150ohm resistors to ground near the transmitter, two dc blocks and then route stripline 100ohm differential line to the LMX2594.  

Now I am confused about the input circuit of the OSC pins of LMX2594. No information on the datasheet (there is some info on the datasheet of LMX2592) - on the EVB there are 50 ohm to ground or 100ohm between the two OSC pins. What is the correct way? please review the entire path from the transmitter all the way to the LMX2594. 

Thanks

  • 0
    TI__Mastermind 28021 points
    Izik,

    The EVB is made to be flexible to multiple configurations.

    We have the 50 ohm to ground on both sides so that it allows the board to be driven differentially, by OSCin, or by OSCin*.

    However, we also have accomodations to place 100 ohms differential across, which is equivalent to two 50 ohm resistors to ground. In your case, I would recommend trying this 100 ohms and removing the 50 ohm resistors because then there is not a noise/spur coupling path to ground.

    Regards,
    Dean