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Part Number: SN75LVCP601

Hi Lee, 

We carefully analyzed the model as now comes the critical phase where the CCAs are in-house and we're in the process of evaluating the circuit performance.

Let’s start with a simple time domain simulation in LineSim using the schematics, as given. 

 (screenshot #1)

The waveforms at each IBIS model look like this:

(screenshot #2)

Note that the output of the transmitter is lower than expected, 450mV where it supposed to be closer to 900mV.

Note that the waveforms at U2 are basically noise only a few mV in amplitude.  Also note that

the waveform at U1 is significantly larger on one of its pins than its other pin.  In addition, note

that the waveform on U3.2p is inverted as compared with U1.2, but U3.2n is not inverted of

U1.3.  This raises a bunch of questions about J11.  Looking at it in the Touchstone viewer, I see

the following:

(screenshot #3)

Note that there is no signal going between the ports that are checked (plotted).

According to the schematics, they seem to expect the main signal path to be

between ports 1 – 2 and ports 3 – 4.  The Touchstone file indicates an open between

those ports.  Actually when I plot the remaining ports in the Touchstone Viewer,

I see that ports 1 – 3 and 2 – 4 are basically a short, and that there is some non-ideal

connection between the remaining ports:

(screenshot #4TI_SN75LVCP601_IBIS_AMI_Analysis.docx)

So it looks like the port ordering of J11 needs to be changed.  I made the same observations

on J12, also. 


Now comes the question about U3.  The way it’s put on the schematics indicates that

this might be a repeater model of some sort.  However, I find no indication in the IBIS

files associated with that symbol that would tell the simulator that the Rx on the left

side of it and the Tx on the right side of it are associated in any way.  If this symbol is

indeed a repeater, the IBIS model should indicate that.  There are keywords in the IBIS

specification for that. 


Finally, It seems that J11, called rx_term, is an S-parameter receiver model for the Rx in U3, and J12 is an S-parameter

driver model for the Tx in U3, along the lines of BIRD158 (or BIRD194), which are actually

included in the v7.0 IBIS specification now.  But I find no indication in any of the IBIS files,

or .ami files that would tell me and the simulator that these S-parameter models are

supposed to be serving that purpose.  Again, there is an official syntax for all that in

the IBIS spec, and the model files should use that to indicate to the simulator what to

do with these models.



  • Hi Shalmon,

    Here is what I get using the TxAMI model of the SN65LVCP601.  This model was developed many years ago it is not up to the current IBIS 7.0 standard.

    As you have indicated in your post, the termination files should be connected Port 1 -> Port 3 and Port 2 -> Port 4.  They will not work any other way.

    If you change your port order to the connections as shown in the touchstone file do the simulation results match with the output below?

    The output voltage is dependent on the DE_CODE specified in the AMI portion of the model.

    For DE_CODE=0 the output is just over 500mV.  For DE_CODE=4 the peak is close to 1000mV.  This aligns with the datasheet expectations.