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SN65LVDT101: LVDS to LVPECL

Stanislav Ryzhkov
Prodigy 10 points

Part Number: SN65LVDT101
Other Parts Discussed in Thread: SN65LVDS100

Hi, 

We are working on testing system and want to use your part as described in diagram below. Does this configuration will work? Screenshot 2026-08-03 004214.png

  • 0
    Prodigy 10 points

    We can't change the UUT and the team of the UUT side used before that TLK1521 in the test system, but now it's obsolete. So we are looking for the TLK1521 replacement. The bandwidth should be ~450Mbps.

  • 0 in reply to Stanislav Ryzhkov
    TI__Genius 17046 points

    Hi Stanislav,

    SN65LVDT101 has a VCC range of 3.0 to 3.6V, so the 2.5V power will cause issues. Do you have 3.3V rail on that board? 

    Regards,

    Matt

  • 0 in reply to Matt Smith
    Prodigy 10 points

    Hi Matt,

    Thank you for the reply! I looked at datasheet again after I posted the question, I can supply SN65LVDT101 with 3.3V too, the question - will it work with the Thevenin termination circuit?

    I did the simulation of generic LVPECL output driver and in simulation the voltages are in the acceptable ranges of the SN65LVDS100. Or another option is to use SY89327LMG-TR with 3.3V instead of SN65LVDT101 with 3.3V.

    I found in the datasheet of TLK1521 that there was built-in termination for output drivers, but can't find any information or circuit for this termination, also the client can't tell what was his calculations when he developed the original version with TLK1521.

  • +1 in reply to Stanislav Ryzhkov
    TI__Genius 17046 points

    Hi Stanislav, 

    Ideally, you should have symmetrical termination where the pullup and pulldowns on each line are equal value to avoid impedance mismatches. (see below). However, if this was done because of fail-safe biasing to introduce an offset in the event of an open circuit, then it should be fine. 

    regards,

    Matt 

  • 0 in reply to Matt Smith
    Prodigy 10 points

    Thank you for the explanation. Yes, we can't change UUT side so we need to adapt ourself to it.