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Original question:

ISO7820LL: LVDS communication question

ISO7820LL: Can I/O use AC coupling?

Jeff Xie
Intellectual 1780 points
Part Number: ISO7820LL


Hi team,

1. For ISO7820LL, can I/O use AC coupling?

2. If not, can I use DC bias on pin and use ac couple to transmit signal?

3. Which is better, DC couple and AC couple for signal Integrity?

Thanks

  • 0
    TI__Guru 55825 points

    Hi Jeff,

    Please find below my inputs,

    1. Yes, AC coupling can be used with ISO7820LL provided the recommended input voltage spec of device are met (both differential & common-mode spec).

    2. Yes, you can DC bias inputs while AC couplings outputs. As long as datasheet recommended specs are met, there is no concern.

    3. It shouldn't matter whether the signal is AC or DC coupled to ISO7820LL as long as the inputs meet datasheet specs. I think AC coupling makes it convenient to add DC bias right at device pins while it isn't as convenient for DC coupled inputs. The only restriction that AC couplings puts on the input is that the input data needs to be DC-balanced (for example, using 8b/10b encoding).

    Please refer to the below Tech Note for more details on various LVDS coupling options.

    www.ti.com.cn/cn/lit/an/slaa840/slaa840.pdf



    Regards,
    Koteshwar Rao