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DS90LV011A: LVDS to SubLVDS Conversion

Hiren Kumbhare
Intellectual 466 points
Part Number: DS90LV011A

Tool/software:

Hello Team,

We are working on the Camera project in which Image sensor output has 4 lane LVDS output and we have SoC which has MIPI CSI2 interface. 

Image Sensor : Python1300

SoC : Rockchip RK3576

As we where looking for solution from LVDS to CSI2 bridge we where not able to find it directly but we found bridge which can convert Sub-LVDS to CSI2. So as per TI App note "SNLA353 – AUGUST 2020", LVDS can be converted to Sub-LVDS using resistor network.

We want to verify that the resistor network in schematics we created are correct and we will be able to convert  LVDS to Sub-LVDS accurately.

LVDS to SubLVDS Conversion

Thanks 
Hiren Kumbhare

  • 0
    Guru 298640 points

    Intel's AN 754 describes how to directly interface LVDS with D-PHY.

  • 0
    Intellectual 466 points

    Hello Clemens,

    Thanks for your quick response.

    We have already selected the Lattice FPGA for the converting SubLVDS to MIPI CSI2 interface of Rockchip SoC RK3576. Attaching image for get more clarity on overall use case.

    We want to make sure the resistor network values we used will accurately convert the LVDS to SubLVDS. So we want TI team to verify resistor network values and schematics to that we can move forward.

    Thanks,

    Hiren Kumbhare

  • +1
    TI__Intellectual 2370 points

    Hi Hiren,

    There are a few problems with the resisitor network you show.

    1. The 1M Ohms resistors shown in the App Note are used to model the receiver's high impendence inputs. They are not to be included in the design.

    2. The 100 ohm resistor in Figure 4.2 models a receiver's internal termination. It should not be included in your resistor network. Depending on whether or not your receiver has internal termination decides what values you need for R1, R2, R3.

    Receiver WITHOUT internal termination (section 3): R1 = 110Ω, R2 = 35Ω, R3 = 50Ω

    Receiver WITH internal termination (section 4): R1 = 222Ω, R2 = 32Ω, R3 = 95Ω

    Regards,

    Jack

  • 0 in reply to Jack Campbell
    Intellectual 466 points

    Hello Jack,

    Thanks for the quick response.

    Our Lattice FPGA has 100 ohm internal termination. 

    We have few more question.

    As R1 value is 222 ohm, we are not able to find the resistor with same value in 0402 package so we found resistor with 221 ohm.  Is this value will work in the resistor network.? Is 0402 package is ok to use?

    As R3 = 95 ohm, we are not able to find the resistor with same value in 0402 package so we found resistor with 95.3 ohm.  Is this value will work in the resistor network.? Is 0402 package is ok to use?

    Thanks,

    Hiren Kumbhare

  • +1 in reply to Hiren Kumbhare
    TI__Intellectual 2370 points

    Hi Hiren,

    0402 is fine. Yes, those resistor values will work.

    Regards,

    Jack

  • 0 in reply to Jack Campbell
    Intellectual 466 points

    Hello Jack,

    Thanks for the quick response.

    We have one more question.


    In this project there are 2 sperate PCB. On 1st PCB there will only image sensor with lens mounted and on 2nd PCB all other section including FPGA , SOC PMIC. Connection between to board are using:

    Sensor Board : Connector PN : MLE-114-01-G-DV-A
    Main Board : Connector PN : FTMH-114-03-F-DH-K

    So question is what will be the better option 
    Option 1 : Using the resistor network on sensor board near to connector
    Option 2 : Using the resistor network on Main board near to Lattice FPGA.

    Kindly let us know your suggestion.

    Thanks,

    Hiren Kumbhare

  • +1 in reply to Hiren Kumbhare
    TI__Intellectual 2370 points

    Hi Hiren,

    The resistor network should be placed closest to the LVDS driver.

    Regards,

    Jack

  • 0 in reply to Jack Campbell
    Intellectual 466 points

    Hello Jack,

    Thanks for the quick response


    This resolved my queries.

    Thanks

    Hiren Kumbhare