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LSF0108: IBIS model selection

Part Number: LSF0108
Other Parts Discussed in Thread: LSF0101, LSF0204

Hi,

I am using LSF0108 as a level shift between 1.8V and 3.3V, when doing the SI simulation, which model should I use in the IBIS model? The IBIS specifies different model for different VCC, but I have VCCA as 1.8V and VCCB as 3.3V, so which one should I use? Should I use one model for 1.8V to 3.3V conversion and the other model for 3.3V to 1.8V conversion?

|******************************************************************************
| Model LSF0101_IO_S
|******************************************************************************
|
[Model Selector] LSF0101_IO_S
|
LSF0101_IO_50A_S 5 volt Vcc
LSF0101_IO_33_S 3.3 volt Vcc
LSF0101_IO_25_S 2.5 volt Vcc
LSF0101_IO_18_S 1.8 volt Vcc
LSF0101_IO_12A_S 1.2 volt Vcc

  • Hi Bruce,

    For 1.8 to 3.3V translation, you would have to use the 3.3V model, configure the port as output.

  • Hi ShreyasRao,

    Thanks for your response.

    The model defines this part as a series switch, so there is no input/output can be assigned, please try it in any simulation tool.

    Bruce

  • Bruce,

    You are right. I can only see input option for the A1 port.

    The IBIS models are usually for logic buffers and not for the passive switch type devices like these.

    Let me check with the modeling team and let you know once i have any updates.

    Would you like to check the LSF0204 spice model if it works for you meanwhile?

  • Hi Shreyas,

    I am afraid LSF0204 model can not been used for my simulation, since is quite different with LSF0108.

    Bruce
  • Understood Bruce.
    I will keep you posted on the progress regarding the LSF0108 device.
    Wanted to know what are the primary characteristics you are trying to simulate using the LSF0108 IBIS model?
    Is it tpd, or rise/fall time or overshoots/undershoots?
  • Hi Bruce,

    Please refer to the instructions to create the FET model in this e2e thread.

    1) Place a MOSFET series, it’ll be on the left and looks like a CMOS.
    2) Select Models – Assign Models/Values by Reference Designator (.REF file)…
    3) In the Design’s parts list, select your component (e.g. U1), under Model/value, go to .IBS, and look around for your ibis file that has the switch model.
    4) Once selected, click on Assign Model, save your .REF file and close this window.
    5) You can then either double click on the box, or select and the go to Models – Assign Models/Values by Component.
    6) In this menu, choose a pin for connectivity. It should select the matching pin based on the model.
    7) Connect to your transmitter device and receiver and you can simulate.

    I have attached the LSF0108 model here for your reference.

    lsf0108.ibs

  • Hi Shreyas,

    Please read my question twice, I don't have problem to assign the model, but don't know which model should be assigned for my application!

    Bruce

  • Hi Bruce,

    Please use the model I have I had attached in the reply above.