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  • TI Thinks Resolved

SN74LVC2G86: Simulation Error

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Replies: 6

Views: 128

Part Number: SN74LVC2G86

Hi Team,

A customer is simulating SN74LVC2G86 and encountered an error in the spice model. Here is his inquiry.

"I need to use the 74lvc2g86 with all voltages translated down say vcc=-3V vee=-8v and same with inputs and outs. But the pspice model when vcc vee is translated to below 0v and i am trying to figure out what is wrong with the pspice models.

I think I found the error in the spice model SN742G86 and probably other models using the LOGIC_lvc.... subcircuit. The error in in the pspice component "EMID" which is supposed to calculated the mid point between VCC and VEE, well is should read EMID MID VEE VALUE = { 0.5 * V(VCC,VEE)} and then the model works correctly given arbitrary VCC and VEE

all the sn74lvc spice models have the same error with EMID just to let you know."

I am checking what simulation tool he is currently using that shows this error.

Regards,

Danilo

  • Hi Danilo,

    Our PSpice models are meant to work within the recommended operating conditions listed in the datasheet. We do not guarantee the models will work outside of this range.

    Thanks!

    Chad Crosby

  • In reply to Chad Crosby:

    Hi Chad,

    Thank you for the clarification.

    Regards,

    Danilo

  • In reply to Danilo Austria:

    Hi Chad,

    Here is the response of the customer regarding the Spice models of SN74LVC.

    EMID MID VEE VALUE = {0.5*(V(VCC,VEE) + V(VEE))}

    should be

    EMID MID VEE VALUE = {0.5* V(VCC,VEE) }

    on all SN74LVC... spice models

    Regards,

    Danilo

  • In reply to Danilo Austria:

    Hi Danilo,

    Thank you for clarifying, I'll work on fixing these.

    Thanks!

    Chad Crosby

  • In reply to Chad Crosby:

    Hi Chad,

    We would like to confirm if the spice models havew been fixed so we could provide the revised models to the customer.

    Regards,

    Danilo

  • In reply to Danilo Austria:

    Hi Danilo,

    As none of our parts are rated to operate below 0V, and we don't have adequate test data to model these parts at those voltages, I won't be changing all of our models. If the customer has specific models he would like changed for his own testing, you can contact me directly with a list of those models and I'll provide a copy with the change made to them.

    I recognize that these negative voltages essentially are Vcc = 5V and vee = 0V, but TI does not guarantee operability for these parts at that range.

    Thanks!

    Chad Crosby

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