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SN65LVDS822: RGB display driver upgrade

Michael Quinlan
Prodigy 20 points
Part Number: SN65LVDS822

I am redesigning a circuit for compatibility with a display that has a clocking rate of 10MHz.  This involves replacing a 75LVDS82 with a 65LVDS822 and a PCB re-spin. 

I have 4 questions, which are,

 

1.Are both devices compatible with respect to the input differential and common-mode levels?  My reading of the data-sheets suggest they are.

2.Do I need 100R differential matching resistors on the input of the 65LVDS822?  (as was the case with the 75LVDS82).

3.In the 75LVDS82 based circuit 27R resistors were placed in series with  each of the RGB output lines presumably for EMC.  Are these required with the 65LVDS822 if I set the SLEW to '0' or open.  The clocking speed is 10MHz

4.At the modest clock speed of 10MHz how critical are the RGB track lengths and impedance.

  • 0
    TI__Mastermind 18655 points

    Hello Michael, 

    1. Correct, the LVDS interface in both devices is compatible in differential voltage and common mode voltage terms. Both meet the requirements of ANSI EIA/TIA-644 standard"]

    2.The SN65LVDS822 has integrated switchable input terminations, therefore, these are not needed.

    3.The SN65LVDS822 has improvements in the EMC and EMI rejection so the 27Ohm resistors are not needed, however, we suggest using place holders with 0 Ohm serie resistors.

    4.Route the bus with minimum trace lengths and a strict maximum of 90 mm, to ensure timing.

    Regards