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LMK00105: AC coupling with LVDS input

Part Number: LMK00105

Hi all

Would you mind if we ask LMK00105?

<Question1>
There is no recommended schematic in case of AC coupling with LVDS input.(Differential input)
If you have it. could you share it?

<Question2>
In relation to <Question1>, is it possible to configure termination resistor 100ohm after AC coupling?
Because we assume that there is the voltage difference 0.3V between CLKIN+ and CLKIN-.

<Question3>
We would like to confirm VCM of Electrical Characteristics on the datasheet.
We assume that VCM range will be small as the input is larger.
It seems that it is opposit. Is our recognition wrong?

Kind regards,

Hirtotaka Matsumoto

  • Dear Matsumoto,

    thank you for reaching out. These are good questions.

    www.ti.com/.../scaa059c.pdf

    The link above is a guide on how to AC couple different signaling such as LVDS. I am sure you will find it usedful. From receive side, you want to make sure the input has the proper common mode. Our device has internal common mode setting . See the user's guide schematic has no biasing for common mode.

    You may place the 100 ohm termination AFTER the AC coupling however make sure the LVDS driver can work under these conditions.

    The datasheet specific the common mode to go up when the input signal is bigger.

    I hope this helps,

    Regards, Simon.