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SN65LVDT388A: Missing Termination Resistor in IBIS Model

Patrick Ruf
Genius 4770 points
Part Number: SN65LVDT388A

Hi,

In the IBIS model of the SN65LVDT388A device the termination resistors are missing. I'm aware of this post: e2e.ti.com/.../1460464

Because the simulation software extract the model out of the schematic I would like to include the termination resistors in the IBIS model rather than include the resistors in the schematic.
I would do the implementation of this resistors in the IBIS model as follows (showing the first input pin pairs):

[Series Pin Mapping] pin_2    model_name     function_table_group
|
1          2       diff_term_110
3          4       diff_term_110
|
|************************************************************************
|                       110 Ohm differential terminator
|************************************************************************
|
[Model]          diff_term_110
Model_type       Series
|                         (typ)               (min)               (max)
|
C_comp                    0.0000pF            0.0000pF            0.0000pF
[Temperature Range]       25.0                85.0                -40.0
[Voltage Range]           3.3V                3.0V                3.6V
[R Series]                110                 132                 88

I'm unshure about the values of [Temperature Range], [Voltage Range] and [R Series].
Can a TI IBIS expert have a look on those values?

Thanks and best regards,
Patrick

  • 0
    TI__Genius 10250 points
    Hello Patrick,

    I will check with the team and get back to you.

    Regards,
    Yaser
  • 0 in reply to Yaser Ibrahim
    TI__Genius 10250 points
    Hello Patrick,

    Your implementation looks good, including the values. I actually thought you may need to switch the values under min and max (basically have -40C/88 ohm under min) but I was told it is OK as is.

    Please note, however, that depending on IBIS simulator, this internal termination might not be interpreted correctly. This is one of reasons that we tend to avoid modeling 100 ohm on-chip termination in the IBIS model. We would be interested to hear how it works for you and what difference do you see between this approach and external 100 ohm approach.

    Regards,
    Yaser