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  1. #1
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    LVDS line to drive single ended controls

    I want to use a pair of LVDS line to drive a single ended control line. The control line is used just to enable/disable an IC.
    Enable is when driven above 2V, ideally 3.3 V.

    I understand that LVDS has a current output and also needs a DC termination in this case. I was thinking of parallel termination and have come up with the scheme in the picture. Will this work?

    Click image for larger version. 

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    Thank you for reading.

    •   Alt10th January 2017, 03:34

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  2. #2
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    Re: LVDS line to drive single ended controls

    Hi,

    I don't think that LVDS gives reliable voltage levels to drive LVCMOS.
    --> use a single LVDS to LVCMOS receiver. It's just a SOT23-6 package. (If I remember right)

    Klaus



    •   Alt10th January 2017, 07:18

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  3. #3
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    Re: LVDS line to drive single ended controls

    Quote Originally Posted by KlausST View Post
    Hi,

    I don't think that LVDS gives reliable voltage levels to drive LVCMOS.
    --> use a single LVDS to LVCMOS receiver. It's just a SOT23-6 package. (If I remember right)

    Klaus
    @KlausST: Thanks for the reply.

    I do not fully understand your answer. I believe the reliability of the LVDS lines is limited when the voltages are between + 100 mV (w.r.t. the offset). Is this the same problem that you refer to in your answer. Or do you refer to any other issue?

    I am looking at ICs too. But wanted to implement with a ckt. if possible.

    Thanks again.



    •   Alt10th January 2017, 09:02

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  4. #4
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    Re: LVDS line to drive single ended controls

    Either use proper LVDS to CMOS conversion - or remove all terminations and probably get sufficient CMOS swing, but also loose LVDS speed.



  5. #5
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    Re: LVDS line to drive single ended controls

    Hi,

    I do not fully understand your answer.
    You need to look at the input threshold specification of what you call "single ended DIO".
    There is a specification for valid low levels (VIL)
    and there is a specification for valid high levels (VIH)

    I doubt your LVDS driver is able to satisfy this specifiaction.

    Klaus



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