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DS90LV804: Integrated Output Termination Purpose

Zachary Davis
Prodigy 70 points
Part Number: DS90LV804

Hello,

I saw that each output of the DS90LV804 has an integrated 100-ohm impedance resistor. This does not seem typical to me. I was curious what the reasoning is for this resistor? How would this effect the output of the LVDS signal versus a normal buffer which would not be 100-ohm terminated directly at the output. 

Thanks,

Zach

  • 0
    TI__Guru* 88835 points

    Hi Zachary,

    Internal 100-ohm resistor provides back termination. Figure 5 of the DS90LV804 is a simplified version of the internal of the LVDS driver. This back termination along with 100-ohm termination at the receiver plus controlled trace impedance, provides optimum signal conditioning from signal integrity point of view. Otherwise there could be reflection - due to impedance mis-match. Please note LVDS driver expects or need 100 -ohm termination at it's output for current return path. On the other hand, a normal buffer would operate at a much lower data rate and thus meeting tight impedance controlled environment is not a concern as much.

    Regards,, nasser