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TMDS442: Could you provide Reference schematic and PCB layout?

Downey Kim
Expert 2675 points
Part Number: TMDS442
Other Parts Discussed in Thread: SCANSTA112

Hi TI team,

The customer wants to proceed with a new design using TMDS422. but I searched the web site and cannot find the reference circuit.

So if possible, could you please send me the reference circuit to me?

Thanks,

Downey kim.

  • 0
    TI__Guru**** 177141 points

    Downey

    Would you please accept my friendship request so I can send the file to you?

    Thanks
    David

  • 0 in reply to David (ASIC) Liu
    Expert 2675 points

    Hi David,

    I have accepted your friendship request!

    Thanks,

    Downey Kim.

  • 0 in reply to Downey Kim
    TI__Guru**** 177141 points

    Downey

    I sent you the board file through the private message, please check.

    Thanks

    David

  • 0
    Prodigy 25 points

    I hate to bother, but would it be possible to also send me reference schematics and pcb if possible?

  • 0 in reply to Andrej Manduch
    TI__Guru**** 177141 points

    Hi,

    Would you please accept my friendship request and then I will send you the files?

    Thanks

    David

  • 0 in reply to David (ASIC) Liu
    TI__Guru**** 177141 points

    Hi,

    I sent you the board file, would you please check?

    Thanks

    David

  • 0 in reply to David (ASIC) Liu
    Prodigy 25 points

    Hi.

    Thanks David, I recived files. I'm sorry it took me so long to respond, but I didn't have OrCad in my disposal so I wasn't able to verify if I recived everything I needed. But now I do and it's very helpfull for me to verify my schematics.

    If you can I would have a few additional questions:

    - I can see that in your schematics, you're grounding HDMI shield also for input side. Is that correct? Should be shielded just sink side?

    - Also datasheet noted that input TMDS terminals are terminated but there is no mention about TMDS sink terminated in chip, but It doesn't look like you're terminating on sink side? Does that mean it's not necessary to terminate them? Or it's recommended to terminate it by inserting terminal resistor between Yx - VCC, Zx-VCC ?

    - I also noticed that you're not connecting unused GPIO pins. I didn't find much about what to do with them in specification just that when GE is disabled than they turn to high impedance pins. Is it preferable to leave them unconnected or it's better to pull them to ground with high value resistor to prevent build static charge on them?

    - Do you also have or planning to produce similiar chip with JTAG boundary scan interface?

    Thanks for schematic, and have a great day.

    Oh, and one more thing, in ultralibrarian is incorrect symbols for TMDS442, I notified them that have mistake there, and they said they are using symbols provided by vendor (TI). And I noticed (but it migt be an issue with OrCad version compatibility) that also in your schematics are not proper symbols, just rectangles with pin numbers (https://imgur.com/lqF8hHu.png)

    So I made my own symbols (all in one simbol: https://imgur.com/a/6X3oJA0, and multiple unit symbol: https://imgur.com/a/KqODnk2 ), If it would help in any way to you (TI), I would gladly share symbol library with you so it would be easier for other people to develop with TMDS442.

    Kind Regards,

    Andrej Manduch

  • 0 in reply to Andrej Manduch
    TI__Guru**** 177141 points

    Andrej

    - I can see that in your schematics, you're grounding HDMI shield also for input side. Is that correct? Should be shielded just sink side?

    With the TMDS442 EVM sitting in the middle between the sources and the sink, have the TMDS442, the input connector shield, and the output connector shield are tied to the same ground ensures the ground potential is the same for all of them. But the GND design may be different if EMI is a consideration.

    - Also datasheet noted that input TMDS terminals are terminated but there is no mention about TMDS sink terminated in chip, but It doesn't look like you're terminating on sink side? Does that mean it's not necessary to terminate them? Or it's recommended to terminate it by inserting terminal resistor between Yx - VCC, Zx-VCC ?

    The termination is expected to be provided by the sink connected to the Yx/Zx.

    - I also noticed that you're not connecting unused GPIO pins. I didn't find much about what to do with them in specification just that when GE is disabled than they turn to high impedance pins. Is it preferable to leave them unconnected or it's better to pull them to ground with high value resistor to prevent build static charge on them?

    GPIO pins can be left unconnected or connected to GND through a resistor if unused.

    - Do you also have or planning to produce similiar chip with JTAG boundary scan interface?

    Would SCANSTA112 fit your need?

    I looked at the Ultra Librarian website, and it looks like the TMDS442 pinout is correct. https://app.ultralibrarian.com/details/78a5ed86-109e-11e9-ab3a-0a3560a4cccc/Texas-Instruments/TMDS442-PNP-128.

    But in the schematic, we created the TMDS442 pinout manually, the Ultra Librarian pinout was created after we finished the schematic.

    Thanks
    David