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SOME NEWBIE question about 74ls74 and 74hc74

Discussion in 'General Electronics Discussion' started by Lxcon Reyes, Dec 27, 2017.

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  1. Lxcon Reyes

    Lxcon Reyes

    Dec 27, 2017
    I'm a computer Science Student tho, i have a little bit of interesting about computer technology, and did some research and self-study. I recently have reached to theory and fundamental that is enough to get into practicals. And again before i do some sort of practical projects I'm really foggy in my mind about 74ls74 and 74hc74 D-type flip flop:
    HERE's what i learned already 74ls74 is a dual d type flip flop with perset and clear; 74hc74 is also a Dual dtype flip flop with set, reset.

    JUST wanna know the real life applications of this two IC and some differences, i'd like to know everthing as much as possible, examples would be nice. HELP me out of this unclear confusing , because is giving me a cancer.

    BTW: the way i'm talking ENG would be strange and may be un-polite? SORRY for that , i dont usually shows up in forums.
    Last edited: Dec 27, 2017
  2. kellys_eye


    Jun 25, 2010
    Logically the devices are identical.

    Have you determined the difference between the 'LS' and 'HC' designations?

    As to real-life applications....... that's just far too wide a request as to be answerable.
  3. Alec_t


    Jul 7, 2015
    'Preset' = 'Set'.
    'Clear' = 'Reset'.
  4. hevans1944

    hevans1944 Hop - AC8NS

    Jun 21, 2012
    Google "74hc vs 74ls" for some informative links. Basically, as @kellys_eye said, they are functionally and logically identical. The 74LSxxx series is low-power Schottky and the 74HSxxx series is high-speed CMOS. The two types can be mixed in the same circuitry ONLY IF you know what you are doing, which you obviously do not. Choose one or the other, not both, for your "practical" project builds. My personal preference would be to use the 74HC74 for better noise immunity and less power dissipation during experimentation but your mileage (or kilometers) may vary.
  5. Petkan


    Feb 9, 2011
    All '74 types are functionally the same and pin compatible.
    Historically 7474 came first, then 74S74, 74LS74, then 74H74, 74HC74, 74HCT74. Texas Instruments site provides full coverage of their differences. The HC types have wider Voltage range (2-6V), the rest are all 5V. HC and HCT have the lowest consumption. It is generally advised to stay with the same family with the whole circuit as their delays are matching and it is easy to avoid 'signal racing". Remember that TTL circuits require fast rising clocks, decoupled power supplies (cap across each IC power pins) and non capacitive loads
    hevans1944 likes this.
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