PSpice User Guide

PSpice User Guide

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PSpice User Guide Digital device modeling October 2019 396 Product Version 17.4-2019 © 1999-2019 All Rights Reserved. The digital primitives comprising the 74393 part reference the IO_STD I/O model in the model libraries as shown: .model IO_STD uio ( + drvh=96.4 drvl=104 + AtoD1="AtoD_STD" AtoD2="AtoD_STD_NX" + AtoD3="AtoD_STD" AtoD4="AtoD_STD_NX" + DtoA1="DtoA_STD" DtoA2="DtoA_STD" + DtoA3="DtoA_STD" DtoA4="DtoA_STD" + tswhl1=1.373ns tswlh1=3.382ns + tswhl2=1.346ns tswlh2=3.424ns + tswhl3=1.511ns tswlh3=3.517ns + tswhl4=1.487ns tswlh4=3.564ns + ) Defining Output Strengths The goal of running simulations is to calculate values for each node in the circuit. For analog nodes, the values are voltages. For digital nodes, these values are states. The state of a digital node is calculated from the output strengths of the devices driving the node DtoA3 (Level 3) name of DtoA interface subcircuit AtoD4 (Level 4) name of AtoD interface subcircuit DtoA4 (Level 4) name of DtoA interface subcircuit DIGPOWER name of power supply subcircuit TSWLH1 switching time low to high for DtoA1 TSWLH2 switching time low to high for DtoA2 TSWLH3 switching time low to high for DtoA3 TSWLH4 switching time low to high for DtoA4 TSWHL1 switching time high to low for DtoA1 TSWHL2 switching time high to low for DtoA2 TSWHL3 switching time high to low for DtoA3 TSWHL4 switching time high to low for DtoA4 Table 7-2 Digital I/O model parameters, continued UIO model parameter Description

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