• State Resolved
  • Locked Locked
  • Replies 9 replies
  • Subscribers 32 subscribers
  • Views 2927 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.

TMDS361B EVM schematic

Sadanori Kato
Guru 36540 points

Other Parts Discussed in Thread: TMDS361B, TMDS361

I have questions about TMDS361B as follows.
My customers are in trouble.
Please give me a reply by June 6 of Japan time.


--------------------------------------------------------------------------------------------
Q1 about Decoupling Capacitors

My customer will connect the ferrite bead to VCC terminals,
configure filters using it between VCC to GND.
All VCC terminals are connected 0.01uF decoupling capacitors.

So, I have a question.
I checked the EVM schematic of TMDS361B(TMDS361_EVM_REV_B.pdf).
Decoupling capacitors of 0.1uF and 1.0uF are connected to VCC terminals.
Are these indispensable?
If they are necessary, how should I connect decoupling capacitors to the VCC terminals?
Please send PCB layout of EVM to me.
--------------------------------------------------------------------------------------------
Q2 about HPD_SINK terminal

Please refer to file of "HPD_SINK.png".
This figure is described p.31 of data sheet.
If 3.3V logic level signal are inputted into HPD_SINK terminal,
I think that the level shifter(MOS FET & resistor structure) is not necessary.
Is it correct?
Moreover, is it possible to use the bipolar transistor instead of the MOS FET in level shifter?
I think that the reason you used the MOS FET is low gate leak current.
Is it correct?
Please tell me about it.
--------------------------------------------------------------------------------------------
Q3 about EVM schematic

I checked EVM schmatic of TMDS361B(TMDS361_EVM_REV_B.pdf) about HPD_SINK terminal.
The schematic of EVM schematic is different from p.31 of data sheet.
Why is this different?
Please tell me this reason.
--------------------------------------------------------------------------------------------
Q4 about connection of TMDS361B and HDMI connector

I checked p.34 of data sheet about SCL* and SDA* lines.
SCL1/SDA1 of TMDS361B and SCL/SDA of HDMI connector are directly connected.
When TMDS361B is power off and is inserted HDMI cable, is it no problem?
Is it necessary to insert the switches between TMS361B and HDMI connector?
Please tell me about it.
--------------------------------------------------------------------------------------------


Best Regards,
Kato

  • 0
    TI__Guru* 76130 points

    Hello,

    Q1. These are not indispensable, the reference schematic has these caps labeled as "DNI" which means "Do not install"
    Q2. correct, if no 5V logic is needed then you can use 3.3V signals on HPD_SINK
    Q3. The EVM is an evaluation module and that is why the HPD signal is connected to a header, to be able to manually manipulate it. the figure on the Datasheet is a merely recommendation but there are many ways to acomplish taht.
    Q4. Again, the figure is juts a representation of a typical application, it is not a real electric diagram. The SCL and SDA lines requires a pull-up to 5V.

    Regards.

  • 0 in reply to Elias Villegas M.
    Guru 36540 points

    Hi, Elias-san,


    Thank you for supporting.
    I still have some questions as follows.


    Q1 about Decoupling Capacitors
    I understood that decoupling capacitors are necessary.
    Therefore, I would like to obtain reference schematic and PCB layout to check original schematics my customer designed.
    Please send them to me.

    Q2 about HPD_SINK terminal
    I understood it.
    Thank you so much.

    Q3 about EVM schematic
    I understood that HPD signals are able to manually manipulate on EVM.
    So, is there another reference design?

    Q4 about connection of TMDS361B and HDMI connector
    I understood that the SCL and SDA lines require a pull-up to 5V.
    What should I note when considering the insertion and removal of the HDMI Cable?
    When SCL and SDA lines are directly connected between TMS361B and HDMI connector,
    TMDS361B is power off, their terminals of TMDS361B is low impedance,
    thereby, their terminals will sink overcurrent.
    I am worried it.
    Should I insert switches in consideration between TMS361B and HDMI connector?
    Please give me the advice about it.


    Best Regards,
    Kato

  • 0 in reply to Sadanori Kato
    Guru 36540 points

    Hi, Elias-san,


    How do you consider about Q1, Q2 and Q4 I asked to you?
    My customer is trouble about these things.
    Please consider about Q4 preferentially, tell me your advices as soon as possible.
    If it is possible, please send another reference schematics to me.


    Best Regards,
    Kato

  • 0 in reply to Sadanori Kato
    Guru 36540 points

    Hi, Elias-san,


    I have not received a reply of TMDS361B Q1, Q2 and Q4 from you yet.
    I am waiting for answer from you.


    Best Regards,
    Kato

  • 0 in reply to Sadanori Kato
    TI__Guru* 76130 points

    Hello,

    Q1. See attached reference schematic.

    7416.12_0518 TMDS361_EVM_REV_B.pdf

    Q2. correct, if no 5V logic is needed then you can use 3.3V signals on HPD_SINK

    Q4. The SCL and SDA inputs are fail safe, this means that they are 5V tolerant when the device is powered off and they will not sink current.

    Regards.

  • 0 in reply to Elias Villegas M.
    Guru 36540 points

    Hello Elias-san,


    Thank you for contacting me despite how busy you are.
    I understood that the SCL and SDA inputs are fail safe, not sink current about Q4.
    So, I have one question.
    Does this means there is no need to insert the switch?
    Please tell me about it as soon as possible.


    Best Regards,
    Kato

  • 0 in reply to Sadanori Kato
    Guru 36540 points

    Hello Elias-san,


    I obtained a additional question from my customer.
    I shows DDC input circuit on p.8 of data sheet as follow.

     

    When the device is powered off, how is fail-safe performed about input voltage of SDA/SCL?
    Please tell me about this method as soon as possible.

    Best Regards,
    Kato

  • 0 in reply to Sadanori Kato
    TI__Guru* 76130 points

    Hello,

    Correct, you don't need the switches.

    As for the last question I've got feedback from design and we can't provide more information about the internal circuitry but it is guaranteed by design that the input is fail safe.

    Regards.

  • 0 in reply to Elias Villegas M.
    Guru 36540 points

    Hello Elias-san,


    Thank you for your information quickly.
    I understood that you could not disclose technical information.
    I can recommend my customer this TMDS361B in comfort.
    Thank you so much.


    Best Regards,
    Kato