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SN54xx and SN84xx chips?

Discussion in 'Misc Electronics' started by Jules, May 16, 2004.

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  1. Jules

    Jules Guest

    Silly question, but what's the difference between SN54xx series chips,
    SN84xx series and 'normal' and SN74xx ones?

    I've got a box of SN54xx chips here and a box of SN84xx ones, and am not
    sure if they're worth hanging on to. If they're drop-in replacements for
    the 74xx equivalent then they may come in useful.

    If they are just drop-in replacements, how come both the 54 and 84 series
    exists at all? I'm assuming there must be differences in temperature
    ranges or something, even if the function and pinouts are the same?


  2. Michael

    Michael Guest

    If memory serves, SN54xx are function and pin equivalents of SN74xx. I
    think the differences are packaging and temperature range. SN54xx that
    I've seen were ceramic DIPs and had wider temperature range. Equip. I
    worked on in the Air Force often used SN54xx.
  3. SN54xxx chips are exactly the same as SN74xxx chips, except for the
    tremperature range specs. 54 series is military temperature range,
    guaranteed to function from -55C to +125C. You will see that some of them
    are slightly slower than some of the commercial chips, but they are hardier
    so it's worth it if you need the broader operating range.
    Standard 74 series chips are only guaranteed to operate from 0C to 70C
    if memory serves.
  4. Don Bruder

    Don Bruder Guest

    The 54xx series is usually the "military grade" - Identical in every way
    except temperature range they can be safely/reliably operated in, to the
    corresponding 74xx chip. Sometimes, depending on the exact chip you're
    looking at, they're a tad slower than the corresponding 74xx chip, but
    they do the same job, using the same pins in the same positions, etc,
    and survive higher (and lower) temps than 74xx chips can cope with. For
    74xx/53xx, as long as the tmeperature that you expect them to operate in
    is within the specs for both, you can mix and match them, swap one for
    the other, etc, without any noticable difference (other than the
    "sometimes" speed difference noted above, which *MIGHT* be big enough to
    "bite" you if you're doing circuits that are fast enough to notice the

    I've never encountered an 84xx chip, but I would presume that they're
    the same way, only in yet another temp. range, or perhaps have a
    different speed or voltage rating.
  5. Zak

    Zak Guest

    I'd guess that the lower speed only appears at on of the temperature
    extremes, and that at eual temperature the speed will be more or less
    the same. Or?

  6. Michael

    Michael Guest

    Well, not exactly "identical in every way except temperature range".
    Enough speculation; I pulled down the dusty 1972 Signetics digital
    supply voltage (S5490) - 4.5v, min. 5.5v, max
    supply voltage (N7490) - 4.75v, min. 5.25v, max.

    Short circuit output current and supply current are also different.
    Further than that I ain't gonna look.
  7. L. Fiar

    L. Fiar Guest

    From a very old ITT data book, in the Texas Instruments
    74 series: 0ºC to +70ºC
    64 series: -40ºC to +80ºC
    54 series: -55ºC to +125ºC
    Same pin-outs and functions, different temperature range.

    Not sure about 84 series, I cannot find them listed anywhere.

    Some others I have found listed in that old book...
    9N series: TTL - as 74 series.
    660 series: HTL logic.
    830 series: DTL logic.
    930 series: DTL logic.
    1800 series: DTL logic.
    8000 and 80L00 series TTL.
    9930 series: DTL logic.
    MC10000 series: ECL logic.
  8. fre

    fre Guest

    Versions of TTL families

    Commercial U(industrial): SN74.... 0 °C..+70 °C

    Extended industrial: SN84.... -25 °C..+85 °C

    Military: SN54.... -55 °C..+125 °C
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