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Wht is 7400 series and 741 ?

Discussion in 'Electronic Basics' started by WAZ, Jun 19, 2006.

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  1. WAZ

    WAZ Guest

    In exame my sir asked me why in logic gates IC no. Starts with 74 , not
    12 or 23 or somthing like that? Plese give me answer.
    NAND 7400
    And in Op-Amp why it is 741? plesae tell me.
  2. The logic that starts with the number 74 are all parts in the TTL
    (transistor-transistor-logic) family, that have compatible input and
    output signals. This family is further subdivided into groups, based
    on improvements in chip technology that either lowered the supply
    current or increased the speed, or both. The 74L family uses less
    current. The 74S series uses more current, but is much faster,
    because of the addition of Schottky diode feedback that prevents
    transistor saturation. The 74LS family is a compromise that uses the
    Schottky diodes but lowered the supply current. The 74F series was a
    much faster chip process, etc.

    The opamp named 741 just got a number that was an arbitrary choice,
    and has nothing to do with the 74 logic family.
  3. It just occurred to me, I have no idea where either the 7400 series
    came from, or where the 700 series of analog numbers came from, but
    here is a better history of TTL logic than I gave, if you are interested.
  4. Guest

    If I recall correctly, the 74xx was Texas Instruments designation for
    their commerical-grade TTL. They also had a parallel 54xx sereies for
    their MIL-spec parts.

    The µA7xx series came from Farichild. Some other memorable members of
    this family were the µA702 and µA709 op-amps, µA711 comparator,
    µA739 dual preamp, µA747 (dual µA741 in a single package). µA741
    was just the next one in the series.
  5. But why did they select 74 and 54 for these purposes? That is
    essentially the crux of the original question. I think the answer is
    something like that your parents used in selecting your name.
    Now, tell me who decided uA7xx would be the series designation and why
    they made this choice.
  6. Guest

    I think this is pretty close to correct. Those were probably just the
    next blocks of numbers not being used by that company. Other companies
    had logic families (such as RTL and DTL) that are now forgotten. Other
    companies had TTL logic with other numbering systems. The 74xx
    nomeclature survived because of the poplarity of TI's TTL series.
    Eventually, even CMOS gave up most of its own numbering system and
    pinouts and was assimilated.

    With the possible exceptions of the LM309 and LM317, who remembers the
    linear regulators that competed with the 78xx and 79xx sereis? In this
    case, I think that the descriptive way the numbers were assigned to the
    78xx, plus the range of popular values, led to the dominance of this
    series and its offspring (the 79xx seiies obviously qualifes as
  7. WAZ

    WAZ Guest

    thnks every body for answering.,
    As you told john 74XX is for commercial purpose. And 54XX is for
    military application.
    Device in 74XX series works over a temprature range 0 to 70'C and over
    supply range 4.75V to 5.25 Volts. And in

    54XX series it works on Temp range -55 to 125'C and Supply range 4.5V
    to 5.5Volts.
    I think that answer is in its Ranges . like for 74XX series first
    digit(not 0 ,but 7) of temp range and first digit of

    voltage range (4) makes 74. and similiarly for 54XX series first digit
    for temp is 5 and first digit for Vol. is 4.

    I think(not sure) this could be answer of my question .Wht do you

    Wazim Shaikh
  8. Random numerical coincidences do not usually capture reality. If they
    did, numerology would be science. By the way, there was a short lived
    64 series that covered the industrial temperature range -25 to +85 C).
    How does your hypothesis account for this?

    I think the real answer came out of some marketing meeting, where they
    looked at what numbers were already taken for similar things and tried
    out how new numbers sounded. In other words, it was a totally
    arbitrary choice that means nothing.
  9. prateek

    prateek Guest

    74XXX series stands for LSI TTL chips. 8XXX is for MSI, TTL chips.

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