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HD3SS3412A: Question about connectivity

Part Number: HD3SS3412A

Dear TI,

The below image is how connect my HD3SS3412A, if there is anything wrong please let me know, because I am trying to do connectivity test with multimeter from the blue circle to the red circle.

Correct me if I am wrong but by default port A should be connected to port B, so theoretically, it should be connected and my multimeter should sound. Did I do something wrong? Please advice. 

Thank you very much! :)

  • AI:

        on the left side, did you connect to Gnd?  A to B or A to C depends on SEL status.

    Regards,

    brian

  • Dear Brian, 

    Sorry, I don't quite get your question, are you talking about A0-, A1-, A2- and A3- should be connected to ground? 

    Also, yes I understand for switching, I need to control SEL pin, but by default A and B should be connected.

    Thank you.

  • AI:

        I just saw something on  your schematic, are they just test point?

       By default, you mean SEL is low?

  • Dear Brian,

    The blue circle is actually SMA connectors, i want to inject signal with signal generator. But before I do that, I want to do connectivity test with multimeter, how do I do that? 

    By default, what I mean is when SEL is low, that is correct.

    Thank you very much! 

  • when SEL is low, A0+  should be connected to B0+ with around 10 ohms. Did you solder ground pin to thermal pad together?

    Regards,

    brian

  • Dear Brian,

    I have checked, the thermal pad is grounded. And I got 0 ohms when probing A0+ and B0+. Is there a specific setting I need to do on the switch instead?

    Next, I have done some testing where I inject 3.3V at A0+ and connect B0+ and B1+ to ground. From here, I can measure 3.3V when probing A0+ and B0+/B1+, the weird thing is that both B0+ and B1+ always shows 3.3V when probing regardless of the switching outcome. Did I test this wrongly?

    Please Advice and thank you.

  • AI:

        Normally don't directly connect B0 to gnd, pls adding 50 ohm  to test .

        Also max differential voltage is 1.8v, means single ended is 0.9v, 3.3v is too much for the device.

       It's better to input ac signal to A0+ and monitor B0+ on scope.

      B1+ should be related to A1+.

    Regards,

    Brian

  • Dear Brian,

    Good evening, sorry for the late reply because I have finally setup the signal generator and oscilloscope. The signal generator is generating LVDS 1.8V and 500MHz .

     

    I connected the signal generator on the green font and then connected the Oscilloscope on the red font. However, it shows no signal at all. I have done the following:

    1) Oscilloscope fully calibrated.

    2) Used different HD3SS3412A to make sure I am not working on a spoiled IC.

    3) Tested the signal generator by connecting directly to the oscilloscope to make sure signal generator is not a problem.

    4) I have double checked the datasheet and all pin configuration looks okay (please take a look as well).

    5) I have confirm thermal pad is connected to ground

    Can you please advice me what to do for me to get signal at the oscilloscope?

    Thank you very much! Slight smile

  • Pls try 0.8v input signal and set SEL high or low.

    Regards,

    brian

  • Dear Brian,

    I am just curious, 1.8V and 0.8V input signal is different? I tried with 1.8v input signal and I set high and low but the result is the same. However, when I reverse the position (figure below)... I get a huge difference reading, about 1.2mV! What is the explanation on this, I am quite confuse why it reacted that way.

    Please advice.

    Thank you very much! Slight smile

  • max differential spec is 1.8v, means single ended is 0.9v.

    If your application is 1.8v single ended, then this is not the right part.

    Regards,

    brian

  • Dear Brian, 

    I do not have 0.9V supply at the moment but while I search for it, I want to ask what is this VBUS? I don't see any explanation on what is it except the tracer need to carry 2A, is this a possible root cause?

      

    Thank you very much! Slight smile

  • Sorry, it's a mistake. We need to correct it.

    Regards,

    Brian

  • Dear Brian, 

    Noted, and I have found out my issue, it seems that my incoming wire that supply power to the board is too thin, I changed my wire to a bigger diameter and it works now. Thank you for your support all the while, Brian. Thank you so much! :)