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SN74ACT14: SPICE MODEL questions

NY
Expert 3040 points
Part Number: SN74ACT14


Hi team, 

1) Customer downloaded Psice model of SN74ACT14, and its register value is 24uohm so seems A - AGND shorted. is it correct model? pelase let me know if this is correct or bag? 

2) Same as above, VCC - GND is differenct with real case, so please confirm.

3) in addtion to above, output impedance is smaller than real case, plase confirm if spice model is different or not.

Best Regards, ny

  • +1
    TI__Guru* 97046 points

    Hi NY,

    Thanks for bringing this to our attention -- these are errors in the model.

    This is the current code:

    .SUBCKT LOGIC_GATE_2PIN_OD_AHC_1i_NAND_PP_ST_SN74ACT14 OUT A B VCC GND
 
.PARAM VCC_ABS_MAX = 7 
.PARAM VCC_MAX = 6 
.PARAM RA = 2.4e-05 
.PARAM RB = 2.4e-05 
.PARAM CA = 2.8e-12 
.PARAM CB = 2.8e-12 
.PARAM ROEZ = 2000 
.PARAM COEZ = 3e-12 
RA  A  GND {RA} 
RB  B  GND {RB} 
CA  A  GND {CA} 
CB  B  GND {CB}

    And this is what it should be:

    .SUBCKT LOGIC_GATE_2PIN_OD_AHC_1i_NAND_PP_ST_SN74ACT14 OUT A B VCC GND
 
.PARAM VCC_ABS_MAX = 7 
.PARAM VCC_MAX = 6 
.PARAM RA = 55e6 
.PARAM RB = 55e6 
.PARAM CA = 2.8e-12 
.PARAM CB = 2.8e-12 
.PARAM ROEZ = 55e6 
.PARAM COEZ = 3e-12 
RA  A  GND {RA} 
RB  B  GND {RB} 
CA  A  GND {CA} 
CB  B  GND {CB}

    The values of RA, RB, and ROEZ should all be increased to 55 Mohm (55e6 ohm) to more accurately represent the typical leakage current of the device.