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DS15MB200 for 1G SFP switching application

Hasith Ishara Kulathilaka
Intellectual 355 points
Other Parts Discussed in Thread: DS15MB200

Hi all,

I am planning to use DS15MB200 for a SFP highspeed line switching application to create a fail-over path. SO LI_0 and LO_ will be connected to the SFP connector, while the

a. SOA_0 and SIA_B will be connected to the controller

b. SOB_0 and SIB_0 will be connected to another SFP

In this configuration if my controller fails , another simple controller will be switch data lines to other SFP.  

My questions are,

1. Is there any application note for this IC?

2. Is there any recommended value for pull up/pull down resisters for ENx,SELx ... etc pins?

3. Where can I find layout guidelines for this? Or can I follow general high-speed routing guidelines?

4. Any decoupling capacitor value recommendations for this?

Thank you

  • 0
    TI__Mastermind 29635 points

    Hi Hasith,

    Thanks for your post, and our apologies for the delay in response.

    Please see answers regarding your questions:

    1.  The only app note I could find that specifically involves the DS15MB200 is a White Paper we released for LVDS Signal Conditioners in general, and this paper can be found under the "Technical Documents" tab on the DS15MB200. Other application information is given in the datasheet itself, starting from the "Tri-State and Powerdown Modes." Is there a particular aspect of the IC that you would like more information about?

    2. For pull-up/pull-down resistors on the logic pins like ENx and SELx, 1 kOhm resistors should be sufficient.

    3. Since this is a WQFN part, you can use the suggestions for the DAP (thermal ground pad underneath the device) regarding soldering suggestions, as seen in SNOA401. Aside from this, you can follow general high-speed routing guidelines for the DS15MB200. It is most important to ensure that impedance continuity is preserved and that the signal traces are coupled in a way that minimizes crosstalk.

    4. Decoupling caps on the power supply depend on potential noise sources in your design. It is common to see at least one 0.1 uF and 0.01 uF cap to help decouple high-frequency noise, and possibly a large cap such as a 1 uF, 4.7 uF, or even 22 uF for decoupling low frequency noise. Smaller cap values should be placed closer to the power pins.

    Thanks,

    Michael