First SW should define the "reasonably accurate model".

The simple logic one, with some prop delays, variable Vcc and some output load characteristics, or with added RLC parasitics, or with all cmos transistor models with their channel widths and lengths and material sheet resistances, or..?

For example (pspice models work in ltspice):

`********************************************************************************`

* SN74HC244.cir

* 2.0

* 2019-11-14 00:00:00

* Texas Instruments Incorporated.

* Standard Logic, SLHR

* 12500 TI Blvd

* Dallas, TX -75243

*

* Revision History:

* Rev 2.0: 01/01/2019

* - Model generated from datasheet values

* - Built using generic logic gate behavioral pspice model V2

* - Built using an automated model which generalizes parts under same family

* - Performance is expected typical behavior at 25C

* - Written for and tested with Tina-TI Version 9.3.100.244 SF-TI

* - Accurate power consumption with dyanmic as well as static Icc

*

********************************************************************************

*[Disclaimer]

* This model is designed as an aid for customers of Texas Instruments.

* TI and its licensors and suppliers make no warranties, either expressed

* or implied, with respect to this model, including the warranties of

* merchantability or fitness for a particular purpose. The model is

* provided solely on an "as is" basis. The entire risk as to its quality

* and performance is with the customer.

*

*[Copyright]

*(C) Copyright 2019 Texas Instruments Incorporated.All rights reserved.

*

*

********************************************************************************

* SN74HC244

********************************************************************************

.SUBCKT SN74HC244 Y A OEZ VCC AGND

XU1 Y A VCC OEZ VCC AGND LOGIC_GATE_2PIN_TRI_STATE_HC_1i_AND_Tristate_CMOS_SN74HC244

.ENDS

.SUBCKT LOGIC_GATE_2PIN_TRI_STATE_HC_1i_AND_Tristate_CMOS_SN74HC244 OUT A B OEZ VCC GND

.PARAM VCC_ABS_MAX = 7

.PARAM VCC_MAX = 6

.PARAM RA = 240000000

.PARAM RB = 240000000

.PARAM CA = 1e-11

.PARAM CB = 1e-11

.PARAM ROEZ = 5000

.PARAM COEZ = 3e-12

RA A GND {RA}

RB B GND {RB}

CA A GND {CA}

CB B GND {CB}

ROEZ OEZ GND {ROEZ}

COEZ OEZ GND {COEZ}

XUA NA A VCC GND LOGIC_INPUT_HC_1i_AND_Tristate_CMOS_SN74HC244

XUB NB B VCC GND LOGIC_INPUT_HC_1i_AND_Tristate_CMOS_SN74HC244

XUOEZ NOEZ OEZ VCC GND LOGIC_INPUT_HC_1i_AND_Tristate_CMOS_SN74HC244

XUG NA NB NOUTG VCC GND LOGIC_FUNCTION_2_HC_1i_AND_Tristate_CMOS_SN74HC244

XOUTPD NOUTG NOUTTPD VCC GND TPD_HC_1i_AND_Tristate_CMOS_SN74HC244

XUOUT NOUTTPD NOUT_INT NOEZ VCC GND LOGIC_TRI_STATE_OUTPUT_HC_1i_AND_Tristate_CMOS_SN74HC244

XICC VCC GND NVIOUT LOGIC_ICC_HC_1i_AND_Tristate_CMOS_SN74HC244

SICC VCC GND VCC GND SW1

H1 NVIOUT GND VIOUT 1

VIOUT NOUT_INT OUTsw 0

SIOFF OUTsw OUT VCC GND SW2

DA2 GND A D1

DB2 GND B D1

DO2 GND OUT D1

DOE1 NOEZ VCC D1

DOE2 GND OEZ D1

RDA1 NA1 GND 1e6

SDA1 NA1 A VCC GND SW2

RDB1 NB1 GND 1e6

SDB1 NB1 B VCC GND SW2

RDO1 NO1 GND 1e6

SDO1 NO1 OUT VCC GND SW2

.MODEL SW1 VSWITCH VON = {VCC_ABS_MAX} VOFF = {VCC_MAX} RON = 10 ROFF = 60e6

.MODEL SW2 VSWITCH VON = {0.55} VOFF = {0.45} RON = 10m ROFF = 100e6

.MODEL D1 D

.ENDS

.SUBCKT LOGIC_INPUT_HC_1i_AND_Tristate_CMOS_SN74HC244 OUT IN VCC VEE

.PARAM STANDARD_INPUT_SELECT = 1

.PARAM SCHMITT_TRIGGER_INPUT_SELECT = 0

ESTD_THR VSTD_THR VEE TABLE {V(VCC,VEE)} =

+(1,0.5)

+(1.8,0.9)

+(2.5,1.25)

+(3.3,1.65)

+(5,2.5)

+(6,3)

ETRP_P VTRP_P VEE TABLE {V(VCC,VEE)} =

+(2,1.2)

+(4.5,2.5)

+(6,3.3)

ETRP_N VTRP_N VEE TABLE {V(VCC,VEE)} =

+(2,0.6)

+(4.5,1.6)

+(6,2)

EHYST VHYST VEE TABLE {V(VCC,VEE)} =

+(2,0.6)

+(4.5,0.9)

+(6,1.3)

ETRUE NTRUE VEE VALUE = {V(VCC,VEE)}

EFALSE NFALSE VEE VALUE = {0}

EBETA BETA VEE VALUE = {V(VHYST,VEE)/(V(NTRUE,VEE) - V(NFALSE,VEE) + V(VHYST,VEE))}

EFB NFB VEE VALUE = {(1 - V(BETA,VEE))*V(IN,VEE) + V(BETA,VEE)*V(CURR_OUT,VEE)}

EREF NREF VEE VALUE = {0.5*(1 - V(BETA,VEE))*(V(VTRP_P,VEE) + V(VTRP_N,VEE))

+ + 0.5*V(BETA,VEE)*(V(NTRUE,VEE) + V(NFALSE,VEE))}

EDIFF NDIFF VEE VALUE = {V(NFB,NREF)}

ESWITCH VSWITCH VEE VALUE = {0.5*(-SGN(V(NDIFF,VEE)) + ABS(SGN(V(NDIFF,VEE))))}

ESWITCH1 VSWITCH1 VEE VALUE = {0.5*(SGN(V(NDIFF,VEE)) + ABS(SGN(V(NDIFF,VEE))))}

GCOMP VEE CURR_OUT VALUE = {SCHMITT_TRIGGER_INPUT_SELECT*0.5*V(VCC,VEE)*(SGN(V(NDIFF,VEE)) + ABS(SGN(V(NDIFF,VEE))))}

GSTD VEE CURR_OUT VALUE = {STANDARD_INPUT_SELECT*0.5*V(VCC,VEE)*(SGN(V(IN,VSTD_THR)) + ABS(SGN(V(IN,VSTD_THR))))}

ROUT CURR_OUT VEE 1

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

EARG NARG VEE VALUE = {V(CURR_OUT,VEE) - V(MID,VEE)}

EOUT OUT VEE VALUE = {0.5*(SGN(V(NARG,VEE)) + ABS(SGN(V(NARG,VEE) ) ) )}

.PARAM MAXICC = 0.0009

.PARAM VT = .7

.PARAM VCC_MIN = 2

EV_VT1 VTN VEE VALUE = { VT }

EV_VT2 VTP VEE VALUE = { V(VCC,VEE) - VT }

ETEST TEST VEE VALUE = {.9*V(VCC,VEE)}

EVTHDIFF VTH_DIFF VEE VALUE = {V(IN,VSTD_THR)}

EVTHPDIFF VTHP_DIFF VEE VALUE = {V(IN,VTRP_P)}

EVTHNDIFF VTHN_DIFF VEE VALUE = {V(IN,VTRP_N)}

EVTNDIFF VTN_DIFF VEE VALUE = { V(IN,VTN) }

EVTPDIFF VTP_DIFF VEE VALUE = { V(IN,VTP) }

GICCVA VCC VEE VALUE = { (-ABS(( (1+SGN(V(VTN_DIFF,VEE)) ) )/2 -1) *

+ 2*MAXICC*((V(IN,VEE)-VT)/V(VCC,VEE))^2)*(1 + SGN(V(VCC,VEE) - VCC_MIN))*V(VSWITCH,VEE)}

GICCVB VCC VEE VALUE = { (ABS(( (1+SGN(V(VTHP_DIFF,VEE)) ) )/2 -1) *

+ 2*MAXICC*((V(IN,VEE)-VT)/V(VCC,VEE))^2)*(1 + SGN(V(VCC,VEE) - VCC_MIN))*V(VSWITCH,VEE)}

GICCVC VCC VEE VALUE = { ( ABS( (1+SGN(V(VTHN_DIFF,VEE)) ) )/2 *

+ 2*MAXICC*((V(IN,VEE)-(V(VCC,VEE)-VT))/V(VCC,VEE))^2)*(1 + SGN(V(VCC,VEE) - VCC_MIN))*V(VSWITCH1,VEE)}

GICCVD VCC VEE VALUE = { (-ABS( (1+SGN(V(VTP_DIFF,VEE)) ) )/2 *

+ 2*MAXICC*((V(IN,VEE)-(V(VCC,VEE)-VT))/V(VCC,VEE))^2)*(1 + SGN(V(VCC,VEE) - VCC_MIN))*V(VSWITCH1,VEE)}

.ENDS

.SUBCKT LOGIC_FUNCTION_2_HC_1i_AND_Tristate_CMOS_SN74HC244 A B OUT VCC VEE

.PARAM AND = 1

.PARAM NAND = 0

.PARAM OR = 0

.PARAM NOR = 0

.PARAM XOR = 0

.PARAM XNOR = 0

GAND VEE N1 VALUE = {AND*V(A,VEE)*V(B,VEE)}

GNAND VEE N1 VALUE = {NAND*(1 - V(A,VEE)*V(B,VEE))}

GOR VEE N1 VALUE = {OR*(MIN(V(A,VEE) + V(B,VEE),1))}

GNOR VEE N1 VALUE = {NOR*(1 - MIN(V(A,VEE) + V(B,VEE),1))}

GXOR VEE N1 VALUE = {XOR*((1 - V(A,VEE))*V(B,VEE) + V(A,VEE)*(1 - V(B,VEE)))}

GXNOR VEE N1 VALUE = {XNOR*(1 - ((1 - V(A,VEE))*V(B,VEE) + V(A,VEE)*(1 - V(B,VEE))))}

RN1 N1 VEE 1

EOUT OUT VEE N1 VEE 1

.ENDS

.SUBCKT TPD_HC_1i_AND_Tristate_CMOS_SN74HC244 IN OUT VCC VEE

.PARAM TPDELAY1 = 1N

.PARAM RS = 10K

.PARAM CS = {-TPDELAY1/(RS*LOG(0.5))}

ETPDNORM NTPDNORM VEE TABLE {V(VCC,VEE)} =

+(2,90)

+(4.5,18.5)

+(6,16)

G1 IN N1 VALUE = {V(IN,N1)/(V(NTPDNORM,VEE)*RS)}

RZ IN N1 10G

C1 N1 VEE {CS}

E1 N2 VEE VALUE = {0.5*(1 + SGN(V(N1,VEE) - 0.5))}

EOUT OUT VEE N2 VEE 1

.ENDS

.SUBCKT LOGIC_TRI_STATE_OUTPUT_HC_1i_AND_Tristate_CMOS_SN74HC244 IN OUT OEZ VCC VEE

EROH NROH VEE TABLE {V(VCC,VEE)} =

+(2,5000)

+(4.5,50)

+(6,38.4615384615385)

EROL NROL VEE TABLE {V(VCC,VEE)} =

+(2,100)

+(4.5,42.5)

+(6,28.8461538461538)

EOEZ N2 VEE VALUE = {1 - V(OEZ,VEE)}

E1 N1 VEE VALUE = {V(VCC,VEE)*V(IN,VEE)*V(N2,VEE)}

GOUT N1 OUT VALUE = {V(N1,OUT)*V(N2,VEE)*(V(IN,VEE)/V(NROH,VEE) + (1 - V(IN,VEE))/V(NROL,VEE))}

LOUT N1 OUT .1n

ROUT OUT VEE 1E8

.ENDS

.SUBCKT LOGIC_ICC_HC_1i_AND_Tristate_CMOS_SN74HC244 VCC VEE VIOUT

.PARAM ICC = 2.5e-07

.PARAM VCC_MAX = 6

.PARAM VCC_MIN = 2

GICC VCC VEE VALUE = {ICC*0.5*(1 + SGN(V(VCC,VEE) - VCC_MIN))}

EGNDF GNDF 0 VALUE = {0.5*(V(VCC) + V(VEE))}

GOUTP VCC GNDF VALUE = {V(VIOUT,VEE)*0.5*(SGN(V(VIOUT,VEE)) + ABS(SGN(V(VIOUT,VEE))))}

GOUTN GNDF VEE VALUE = {V(VIOUT,VEE)*0.5*(SGN(V(VIOUT,VEE)) + ABS(SGN(V(VIOUT,VEE))))}

.ENDS