74LS245 vs 74HCT245 ?

Discussion in 'General Electronics Chat' started by CVMichael, Apr 17, 2011.

  1. CVMichael

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    Aug 3, 2007
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    Last edited: Apr 17, 2011
  2. Audioguru

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    Dec 20, 2007
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    The output high voltage of a high speed Cmos 74HCT245 is 5.0V.
    The output high voltage of a TTL 74LS245 is only about 2.7V to 3.5V.
    The IC it drives might need a minimum input high voltage of 3.5V, look it up.
     
  3. nomurphy

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    The 'T" in HCT means TTL compatible.
     
  4. CVMichael

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    What about differences in speed?
     
  5. nomurphy

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    It should be okay, the LS part will use more power.

    The schematic is kind of fuzzy for me, but it seems to me that the OE pin is floating and that only one of the three output signals has a corresponding input?
     
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