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WTD LTSpice 74HC04 spice or subcircuit

Discussion in 'Electronic Design' started by Joe G \(Home\), Apr 7, 2007.

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  1. Hi All,

    Does anyone know where I might be able to obtain this model.

    Thanks in advance.

    Regards
    Joe
     

  2. Hello Joe,

    The important question is what behaviour should be modeled.

    If you want make a simple digital inverter, then an A-device with Vhigh,
    Vlow, Ref, Trise and Td will fit. This A-device will be simulated very fast.
    Vhigh=5 Ref=2.5 Td=5 Trise=5
    I recommend to add a 50 Ohm resistor in series to the output. Adding
    the built-in input diodes may be also necessary if the input voltage exceeds
    the rails.

    I have written a small library based on the A-models. It's in the
    LTspice Yahoo group. The devices fom this library will run slower
    than pure A-devices.
    http://tech.groups.yahoo.com/group/LTspice/

    NXP offers a real transistor level model. A simulation will run slower
    than with a simple A-device of course too.
    http://www.standardics.nxp.com/support/models/spice/zip/hc.zip
    http://www.standardics.nxp.com/support/models/spice/


    Best regards,
    Helmut


    Example schematic(circuit), file name "74hc04_a.asc"

    Version 4
    SHEET 1 880 680
    WIRE -528 -16 -576 -16
    WIRE -576 16 -576 -16
    WIRE -48 64 -48 32
    WIRE -576 128 -576 96
    WIRE -464 176 -576 176
    WIRE -48 176 -48 128
    WIRE -48 176 -192 176
    WIRE 64 176 -48 176
    WIRE 160 176 128 176
    WIRE 368 176 240 176
    WIRE -576 208 -576 176
    WIRE -48 240 -48 176
    WIRE -576 336 -576 288
    WIRE -48 336 -48 304
    FLAG -48 32 VCC
    FLAG -48 336 0
    FLAG -576 336 0
    FLAG 368 176 out
    IOPIN 368 176 Out
    FLAG -464 176 in
    IOPIN -464 176 Out
    FLAG -576 128 0
    FLAG -528 -16 VCC
    FLAG -192 176 in
    IOPIN -192 176 In
    SYMBOL Digital\\inv 64 112 R0
    WINDOW 123 -17 130 Left 0
    WINDOW 39 -12 162 Left 0
    SYMATTR InstName A1
    SYMATTR Value2 Vhigh=5 Ref=2.5
    SYMATTR SpiceLine Trise=5n Td=5n
    SYMBOL res 144 192 R270
    WINDOW 0 32 56 VTop 0
    WINDOW 3 0 56 VBottom 0
    SYMATTR InstName R1
    SYMATTR Value 50
    SYMBOL diode -64 128 M180
    WINDOW 0 24 72 Left 0
    WINDOW 3 24 0 Left 0
    SYMATTR InstName D1
    SYMATTR Value DD
    SYMBOL diode -64 304 M180
    WINDOW 0 24 72 Left 0
    WINDOW 3 24 0 Left 0
    SYMATTR InstName D2
    SYMATTR Value DD
    SYMBOL voltage -576 192 R0
    WINDOW 123 24 160 Left 0
    WINDOW 39 24 132 Left 0
    SYMATTR InstName V1
    SYMATTR Value PULSE(0 5 10n 5n 5n 45n 100n)
    SYMATTR Value2 AC 1
    SYMATTR SpiceLine Rser=50
    SYMBOL voltage -576 0 R0
    SYMATTR InstName V2
    SYMATTR Value 5
    TEXT -96 392 Left 0 ;optional
    TEXT 0 336 Left 0 !.model DD D(Cjo=5p Rs=10)
    TEXT 64 -32 Left 0 ;74HC04
    TEXT -584 -128 Left 0 !.tran 0 250n 0 .1n
    TEXT -584 -96 Left 0 !.options plotwinsize=0
    RECTANGLE Normal 320 432 -144 -64 2
    CIRCLE Normal 16 368 -112 -32 2
     
  3. Hi Helmut,

    Many thanks for your reply.

    Application RF oscillator - so NXP spice models look more attactive.

    I would like to integrate the spice net lists from the NXP 74HC models in
    to LTSpice.

    Do you have any guidance to do this?

    Regards
    Joseph
     
  4. Hello Joseph,

    LTspice is strictly standard SPICE on a netlist level.
    This means you can directly run the examples(.cir) from the NXP-zip-file.

    There is no SPICE standard for schematic entry. This means
    symbols are different in every SPICE with schematic entry.
    I think that you prefer a schematic instead of a pure netlist.
    LTspice offers you different possibilities for symbols.
    There are symbols you can edit on an instance level
    and others you can't. Both types are useful the same in many cases.
    It's a tradeoff regarding versatility and fool proof.
    In some cases it's necessary to go with one of them.

    It's Easter and so the Easter bunny will bring you a gift via email.
    Let's hope your email address is valid. If not, send it to my address.
    It's a schematic example of an LC-oscilator with the 74HC04U
    /74HC04 using the NXP-MOSFET models..
    Just replace the value 74HC04U with 74HC04 to switch to a 74HC04.
    LC-oscillators should be made with the unbuffered 74HC04U!

    Happy Easter!

    Best regards,
    Helmut

    PS: I remember having read that Australians have banned the
    rabbits/bunnies from school books. Is that true?
     
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