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14606Re: [cosmacelf] IC Date Codes

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  • ajparent1
    Dec 14, 2013

      74H was higher threshold and power for improved noise margins compared the plain 74.


      74L  and LS were lower power than 74.


      74S and later AS then F then AF were faster, faster, faster...

       

      Then the CMOS generation , 74C, HC, HCT, and likely others...


      The biggest thing to watch for is family to family incompatibility.   

      The OLD 74C would not work with most Bipolar  TTL  without pullups.

      74S and 74LS didn't get along well without watching fanout and fanin

      as 74S could pull down well but LS could not pull the higher current 

      inputs down well.


      I worked with all of them and have large samples of most.


      Allison

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