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Multidrop Bus option using M-LVDS

Ryan Sequeira
Prodigy 30 points
Other Parts Discussed in Thread: TIDA-060017

I am trying to evaluate options for a back-plane interface ( order of 20-50Mbps or higher) with cost being a major driving factor. I seem to have narrowed down to either M-LVDS or RS485 (I've seen xcvrs in the 25Mbps range from TI, which may be also be OK).  What I am looking for is:

1. A good reference design/application note or any data that shows this back plane design implementation?

2. Given that the speeds are 50Mbps, what would be the recommended link layer ? Any recommendations on the TI micro controllers that can be interfaced to these bus xcvrs? Are there any micro controllers supporting high speed serial interfaces (considering UARTs on existing uC may not be suitable)

Regards

R

  • 0
    TI__Guru 62920 points
    Hello,

    Either RS-485 or MLVDS would work in this application, although MLVDS may be a more natural choice. It is commonly used in backplane communication, can handle the 50 Mbps data rate, and generally should have lower power consumption. I'll see if someone more directly responsible for MLVDS products at TI can give some guidance on reference materials and MCU selection.

    Regards,
    Max
  • 0 in reply to Miguel Robertson
    Prodigy 30 points

    Thanks Max,

    I have a further follow basic question on using M-LVDS. I understand this would be the more natural choice for a multi-drop backplane communication. However I have still have this nagging question:

    1. Let us assume I have an IC that is a M-LVDS driver. I understand the driver inputs per the TI product line up can be TTL, PECL, CML etc., I am trying to find out if any microcontroller can be interfaced with these M-LVDS ICs. If yes, what interfaces do you suggest (UART or any other HI Speed serail bus etc)

    2. Since LVDS is so common, from any of your previous support experience, can you suggest what micros are available from TI that can interface and leverage the M-LVDS IC speeds upto 30Mbps?

    3. What are the typical high speed serial interfaces supported by TI micros ? OR do these M-LVDS tranceiver typicall interface with High speed interfaces available in FPGA/CPLD only?

    Regards,

    Ryan

  • 0 in reply to Ryan Sequeira
    TI__Genius 10250 points
    Hello Ryan,

    1. One possibility is SPI interface, but it could be other interfaces since LVDS/M-LVDS is really pure physical layer interface. We have seen people use SPI over LVDS, and we also have some collateral on that:
    TI Design - TIDA-060017 Transmitting SPI Signals Over LVDS: www.ti.com/.../TIDA-060017 .

    2. In principle, any micro can interface with LVDS/M-LVDS. Please look for the micro that satisfies your other requirements and if you have questions on micro selection, please post another e2e question on that specifically so that it would be routed to the right people who support micros.

    3. LVDS/M-LVDS can be used with micros, FPGAs, ASICS, etc.

    Also, here are some resources on M-LVDS for backplanes:
    • 2 Videos on M-LVDS in backplanes: training.ti.com/lvds-training-series
    • Blog: The top 5 questions when using M-LVDS in backplane applications: e2e.ti.com/.../the-top-5-questions-when-using-m-lvds-in-backplane-applications

    Regards,
    Yaser