TINA/Spice/SN74LV123A: No state change on Pspice

RYO

Intellectual 2000 points

Part Number: SN74LV123A
Other Parts Discussed in Thread: TINA-TI,

Tool/software: TINA-TI or Spice Models

Hello in Simulation team,

I got a question about SN74LV123A's spice model. He said the state doesn't change when the A, B or CLR are changed. On the other hand, the TINA-TI works well with the model. Both are downloaded from ti.com lately so that the files are latest version. I don't think bugs are in these files.

I put 2 images in order to explain what is happening. Can you point out what is not good?

Thank you,
RYO

over 7 years ago

0 RYO over 7 years ago

TI__Intellectual 2000 points

Sorry, I could not attach the image. Here is PDF:

SN74LV123A.pdf

0 Karthik Kulkarni over 7 years ago in reply to RYO

TI__Intellectual 1090 points

Hello RYO,

I downloaded the PSPICE model from TI website and configured the test bench as per the results seen in the pdf provided above.

The simulation seemed to run fine.

Please find the schematic & the results below:

Schematic:

Results:

The difference I see between the two PSPICE schematics are that the parameters(R_EXT & C_EXT) are not passed in the PSPICE schematic shared by you. Those two parameters are used inside the sub circuit and hence need to be passed as per the external REXT and CEXT value. Please let me know if the same works fine for you after passing the parameters.

Thanks & Regards,

Karthik

0 RYO over 7 years ago in reply to Karthik Kulkarni

TI__Intellectual 2000 points

Thank you, Karthik.

I have one more question regarding this. What is the valid range of C_EXT and R_EXT of this model in PSPICE then? In my TINA-TI, the setting of R_EXT=1k and C_EXT=1u works fine. I think the IC also works fine when I put these components on the circuit.

Best regards,
RYO

0 Karthik Kulkarni over 7 years ago in reply to RYO

TI__Intellectual 1090 points

RYO,

Looking at the subcircuit, I don't see any limitations as such on the range of R_EXT and C_EXT. However, using lower values of R and C might lead to convergence issues, As for the IC, the datasheet seems to specify min range for R_EXT only(1K/5K depending on VCC).

Regards,

Karthik

0 RYO over 7 years ago in reply to Karthik Kulkarni

TI__Intellectual 2000 points

Hello Karthik,

Thank you so much for your explanation. I understood.

Best regards,
RYO

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TINA/Spice/SN74LV123A: No state change on Pspice