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THS7372: Typical application questions

daniel
Genius 5095 points
Part Number: THS7372

Hi Team,

Please kindly help on below questions. Thanks

1. Data sheet Figure84 has pull low resistor 37.4ohm on buffer input termination, but EVM show 75ohm. What value should we follow? (We already control the RGB trace impedance are 75ohm).

2. Data sheet Figure84 has series 75ohm on output termination. Do we still need these resistors if we already control the RGB trace 75ohm impedance?

3. We add a Pi-filter, is the sch OK? The pull down resistors should be 75ohm or 150ohm?

Thanks

  • 0
    Guru 140200 points
    Hi Daniel,

    what do you mean by "we already control the RGB trace 75ohm impedance"? That the copper traces are 75R microstrip transmission lines?

    The idea of matching the characteristic impedance of a cable is to have a series termination resistor with the impedance of cable at the driver side and a parallel termination resistor with the impedance of cable at the receiver side. So, these two resistors are always necessary.

    Be careful with pi-filters in the signal path. They can erode the cable termination and make the things worse. I have seen applications with such pi-filters where the signals were totally ruined! So, check the circuit first without pi-filter and then with them. And test it with all cables lenghts as seen later in the application!!

    Kai
  • 0 in reply to kai klaas69
    TI__Genius 16735 points
    Hi Daniel,

    Do you still have more questions or did Kai help you resolve this issue?

    I am going to mark the thread resolved by go ahead and reply if you still have more questions.

    Thanks!
    -Karan