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SN65LVDS390: how to extend the SPI communicating distance

Betty Guo
Expert 7300 points
Part Number: SN65LVDS390
Other Parts Discussed in Thread: TLC5957, TIDA-060017, SN65MLVD040, DS90LV048A

Hi,

customer use SPI interface and the distance between the MCU and driver board is about 3m. How to extend the communicating distance?

I promote the SN65LVDS390 to customer, is it the best suitable device for it? 

Meanwhile,there are 2 pins need GPIO control, can SN65LVDS390  be used for it?

thank you.

  • 0
    TI__Genius 10250 points
    Hello Betty,

    LVDS is a good option to extend reach of SPI. There are several options and the right solution depends on the application. Please tell us more about their application, including the SPI clock rate, which SPI signals and direction of data. We can then suggest the best solution.

    Regards,
    Yaser
  • 0 in reply to Yaser Ibrahim
    TI__Expert 7300 points

    Hi Yaser,

    It used to control LED driver TLC5957, you can see the datasheet by click http://www.ti.com/lit/ds/symlink/tlc5957.pdf 

    usually, we use 100Hz frequency in display application, the SPI data has 48bit, so the SPI clock should be higher than 500Hz.

    thanks.

  • 0 in reply to Betty Guo
    TI__Genius 10250 points
    Hello Betty,

    To extend reach of SPI signals, they would need a driver chip on the transmit (controller) side and a receiver chip on the receive side (TLC5957). I am assuming the direction of all signals is from controller to LED driver and the number of signals is 4. Is this correct? Also, do they have multiple LED drivers daisy chained, as indicated in the Typical Application Circuit (Multiple Daisy Chained TLC5957s) in the TLC5957 datasheet? The SPI DATA goes to only the first TLC5957, while SPI CLK goes to all TLC5957s... Please confirm.

    Please tell me more about the 2 GPIO signals. Are they going from controller to LED driver too? What is the signal rate and distance?

    Regards,
    Yaser
  • 0 in reply to Yaser Ibrahim
    TI__Genius 10250 points
    Hello Betty,

    I forgot to mention that we have a recent TI Design specifically for SPI over LVDS:
    TIDA-060017 Transmitting SPI Signals Over LVDS: www.ti.com/.../TIDA-060017 .
    Please note that as I said, the right LVDS devices depends on the application.

    Regards,
    Yaser
  • 0 in reply to Yaser Ibrahim
    TI__Genius 10250 points
    Hi Betty,

    Thanks for sharing the block diagram via email.

    Since the output of the controller drives multiple TLC5957s, this is a multi-drop configuration and it is better to use M-LVDS driver on the controller side. A good part for this is SN65MLVD040. They should put a 100 Ω termination at the output of SN65MLVD040 and 100 Ω termination at the last (farthest) TLC5957 board only.

    On each of the TLC5957 boards, they can use DS90LV048A LVDS receiver.

    Regards,
    Yaser