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SCAN15MB200

Other Parts Discussed in Thread: SCAN15MB200

 

I'm developing boundary scan test for our scanner product and now focusing to backplane connector.  My idea is to do adapter board were SCAN15MB200 LVDS buffer outputs are connected via backplane connector to the LVDS receiver in the baseboard. There are both AC-coupled and DC-coupled signals in the backplane connector.  

 

Can I leave buffer input pins floating when output is connected?  And can I left other unused LVDS IO’s floating? Boundary scan tool is using IO’s in 10MHz clock frequency. For boundary scan testing I don’t have need for high speed signalling.

 

I could not  find SCAN15MB200 BSDL file from the webpage. Is it available somewhere?

  • Hi Taneli,

    Regarding the inputs, I would implement fail-safe biasing on the input so that even if there is no input to the SCAN15MB200, the output will be driven to a known state when it is connected. It is not desirable to leave an open circuit on the input pins.

    For the unused outputs, please assert the corresponding Output Enable pins (ENA_n, ENB_n, ENL_n) low if the LVDS channel is unused. This will place the channel output safely into tri-state.

    Lastly, it will take some time to search for the SCAN15MB200 BSDL file. I am aware that we mention this BSDL file in the datasheet, but many of our National Semiconductor Archives have been shut down or moved to other locations internally. Please allow a few days for me to get back to you regarding whether we can locate this part's BSDL file.

    Regards,

    Michael
  • Thanks Michael. Take your time to find the BSDL file.

    BR,

    Taneli

     

  • Michael,

    I'm helping Taneli with her request - just wanted to see if you could provide a rough timeline on getting the BSDL file. A couple more days? Next week sometime?

    Thanks,

    Paul

  • Hi Paul,

    I should be able to get it back this week. I have managed to find a BSDL file, but I have not been able to compile it successfully with a verification tool I have, due to some syntactical issues. I hope to work through these to provide an adequate, error-free BSDL file in the coming days.

    Regards,

    Michael
  • Thank you very much!!

    Paul
  • Hi Paul and Taneli,

    I was able to recover the SCAN15MB200 and edit it so that it could compile successfully in a local BSDL compiler. Please see attached and let me know if this works.

    SCAN15MB200.bsdl

    If this revision of the BSDL is adequate, I will have the file officially posted on TI.com.

    Thanks,

    Michael

  • Thanks a lot Michael,

    I will test BSDL file once I get board with this device. Design is not finalized yet.

    -Taneli

  • Has the BSDL file been verified yet an if so, can you please post it to the webpage? Furthermore, is there an eval. card I can get and if so, is there a users manual avail? Lastly, if there are any appnotes on the BSDL functionality of the device, can you please add those to the webpage?
  • BSDL file is verified and working nicely without any modifications. I found SCAN15MB200EVK eval board information from the web but board was not available on spring time. 

    -Taneli

  • Good to know the BSDL is working. Any idea if TI will officially post it to the product webpage? As for the Eval. Card, it seems to be listed on disti websites as OBSOLETE and I cannot find any mention of it on TI's website. Just wondering what's the path forward here.

  • Hi Taneli,

    Thanks for confirming that the SCAN15MB200 BSDL is working as expected.

    Hi Steven,

    We will work to get the SCAN15MB200 BSDL available on TI.com, which should be up on the web soon. In the meantime, please download from the link in my post above.

    Regarding the evaluation board, we do not have access to any of the original design files and therefore are unable to re-build the original SCAN15MB200EVKs. Unfortunately, there are currently no plans to create a new SCAN15MB200EVK. If you would like, we are happy to review schematics or design layouts that you may have with this part and make recommendations to help with your design.

    As for your question about BSDL functionality, this follows the standard definition and syntax described by IEEE 1149.1 JTAG Boundary Scan standards. Thus, rather than a User's manual for the BSDL file, I would recommend referencing the IEEE 1149.1 syntax for interpreting the SCAN15MB200 BSDL file.

    Regards,

    Michael

  • Need some help with compatibility.

    The data sheet claims compatibility with receiving “CML” differential signaling. No example circuit is shown. Wanted to know if the part is compatible to receive DVI which transmits with “CML” 3.3V.

    My plan was to use an “interop” circuit (Figure 6) from TI document: www.ti.com/.../snla180.pdf The circuit would be used in 1149.6 mode only.
  • Hi Steven,

    The SCAN15MB200 will only operate with LVDS-compatible signaling. I typically see CML signals that are biased at about 1.6 V and exhibit up to a maximum 1600 mVpp swing (meaning that the range on either polarity is 1600 +/- 800 mV). You will need to reduce the voltage swing such that the input differential voltage is within 100-2400 mV when measured differentially at any point in time, and the input common mode is within 0.05-3.55 V, as indicated in the datasheet.

    The voltage swing of CML signals actually will fit within the SCAN15MB200 datasheet LVDS input specifications, but you will need to change the common mode such that it is within the 0.05-3.55 V specification. I see no issue in the interop circuit in Figure 6 that you refer to. This circuit uses AC coupling caps to isolate the VCC offset from the CML source and then implements a voltage divider to set the appropriate common-mode voltage across the LVDS receiver (should be around 1.2 V) while also providing a failsafe bias for the LVDS receiver. I recommend using higher value fail-safes (such as R1 (resistor to VCC) = 13 kOhm and R2 (resistor to GND) = 8 kOhm) to further minimize waveform distortion.

    Thanks,

    Michael