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Original question:

TMDSCNCD28388D:

TMDSCNCD28388D: need of buffer/tranceiver/driver/receiver

Gerald
Genius 9570 points

Part Number: TMDSCNCD28388D
Other Parts Discussed in Thread: C2000WARE, , SN65LVDM1676, SN65LVDM1677

Hi Experts,

Our customer have a concern as shown below:
"i want a signal on a line such as coaxial cable, twisted cable, .... As I understand, respectively, on each end of the coaxial cable a buffer is needed and you have to pay attention to the impedance of the medium; while on each end of a twisted cable a differential receiver / driver / tranceiver is needed (eg, LVDS, RS485, RS422 ...). the doubts I ask myself are the following:
- if the signal frequency is low, can I do without buffer, receiver, tranceiver, driver, ....? If so, what is this frequency and the low capacitance TVS diodes are sufficient against ESD and EFT? Do I find the frequency in the data sheets?
-Can the cable extend it for a longer distance at low frequencies?
-At low frequencies, unbuffered / driver / tranceiver / receiver can I carry the signal in a noisy environment?

I'm studying the MCU063B (002) _Sch.PDF board in the folder:
/opt/ti/c2000/C2000Ware_4_01_00_00/boards/controlCARDs/TMDSCNCD28388D/Rev.B
I want to make some changes. My application is subjected to strong accelerations and I fear that the inertia of a board card could quickly ruin the socket.
I intend to carry many signals through either parallel or coaxial connection for a length of 10-15cm.
The signals I want to carry are EPWMs, GPIOs and SDFM channels.
What buffers would you suggest for OUTPUT channels and INPUT channels?
The board I would like to draw is less than half a meter from about twenty synchronous motors

Frequency of EPWMs, GPIOs and SDFM channels is less of 600kHz"

Not sure if this is the right forum to ask. If not, we will appreciate it if you can move this to a more appropriate forum. We hope to receive your advice. Thank you.

Best regards,

Gerald

  • 0
    TI__Mastermind 42195 points

    Gerald,

    For any signals which run on long cabling they will likely need some sort of transceiver or buffer. Yes having lower frequency signals can help, but you will still face immunity issues at some point. This is very dependent on the environment and hardware used, but generally I expect that you'll need a buffer.

    Interfaces like the controlCARD interface are very common in things like Server Power supplies, this allows more flexibility in control solutions, but in applications which see mechanical stress this is not recommended. The customer should not directly use the HSEC interface.

    I would recommend the use of some buffer or transceiver, but I think the exact part select would be best left to someone in that team.

    As for being 1/2 of a meter away from 20 synchronous motors, this does indicate the potential for some noise, but it does not provide enough information to determine the effect of EMI on these signals.

    Let me see if I can ask this to be moved to someone who can directly recommend the parts you're looking for.


    Regards,
    Cody 

  • 0 in reply to Cody Watkins
    TI__Genius 9570 points

    Hi Cody,

    Thank you for the information. I will wait for further updates.

    Kind regards,

    Gerald

  • 0 in reply to Gerald
    TI__Genius 9570 points

    Hi,

    Please also see additional info/response from our customer:
    "my research has focused on sn65lvdm1676 or sn65lvdm1677, I need a large number of drivers / tranceivers because I would like to use all the available ePWM and SDFM pores, plus a dozen GPIO ports (although I think I will drive these peripherals at a maximum frequency 600kHz). I have seen the buffer list, implementing a buffer is difficult for me because I do not know how to determine the level of electrical noise in the environment in advance"

    Thank you and kind regards,

    Gerald

  • +1 in reply to Gerald
    TI__Guru* 77362 points

    Hi Gerald,

    I believe your concerns correlates to the impact of the LVDS signal integrity per the cable length and the data rate; as 600KHz for 10-15cm works okay.

    Please help see How Far, How Fast Can You Operate LVDS Drivers and Receivers? to help guide the implementation.

    Also, see High-Speed Interface Layout Guidelines to help avoid any additional noise that could be incorporated from the layout, thanks.

     

    Best Regards,

    Michael.

  • 0 in reply to Michael Ikwuyum
    TI__Genius 9570 points

    Hi Michael,

    Are single-ended buffers not usable in this application compared to differential buffers (would using this help to shed less cable)?

    Best,

    Gerald

  • +1 in reply to Gerald
    TI__Guru* 77362 points

    Hi Gerald,

    The recommendations and guidelines are applicable for both the single ended and the differential buffers, thanks.

     

    Best Regards,

    Michael.