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Original question:

[FAQ] DS90LV011A: LVDS Driver to Sub-LVDS (S-LVDS) Receiver

DS90LV011A: Driving sub LVDS receiver with LVDS driver

Jonathan King
Prodigy 40 points
Part Number: DS90LV011A

Tool/software:

I am following the guidance of this thread:

 [FAQ] DS90LV011A: LVDS Driver to Sub-LVDS (S-LVDS) Receiver 

My question: is it ok to have the resistor network near the driver, or must it be near the receiver? I think that were I to use this circuit, it would need to be near the receiver to avoid signal reflections:

My receiver is much more space constrained than the driver though. I wonder if I can use this circuit and place R1/R4, R2/R5, and R3/R6 near the driver, and just R9 at the receiver:

Does that sound right?

  • +1
    TI__Genius 10066 points

    Hi Jonathan, 

    Ideally you should place the step-down resistor network within a few inches of the receiver since any impedance mismatch on the line will cause signal reflections. However, I understand if things are space constrained and you have to place it further away. If this is the case, you may have to run a few trial and error simulations to understand what the new overall characteristic impedance of the transmission line is at your operating frequency and properly terminate it according to the new impedance. I would recommended trying a few different placement options to figure out what the optimal location would be if you can't place it close to the receiver. If you are placing the network next to the driver, you should try to match the driver output impedance and then terminate accordingly. 

    Regards,

    Matt 

  • 0 in reply to Matt Smith
    Prodigy 40 points

    Thanks for the input, Matt! The interface will operate at 480 Mbps. I will put in the step down network in as close to the receiver as I can manage (which will likely be about 5 inches away). Hopefully that will be sufficient. I'll also put in the placements to allow trying it at the transmitter but closer to the receiver will be my default. Will report back results when boards are made in a couple months.

  • 0 in reply to Jonathan King
    TI__Genius 10066 points

    Sounds good, Jonathan. Feel free to reach back out with any other questions or concerns.