Counter Data sheet interpretation help

Discussion in 'General Electronics Chat' started by BetaBeta, Nov 23, 2012.

  1. BetaBeta

    Thread Starter New Member

    Nov 23, 2012
    1
    0
    Hello!

    I am having a few issues interpreting this data sheet for a 74hc163 counter:

    http://www.ti.com/lit/ds/schs154d/schs154d.pdf

    And am unsure how to calculate the loading that I can apply to it.

    MY lecturers have referred to a 'max' loading, but surely the higher the resistance of the load the better, because it will draw less current from the chip?

    How do I work out the limits of the loading value that I can apply to each pin?

    Thanks!
     
  2. KJ6EAD

    Senior Member

    Apr 30, 2011
    1,425
    363
    I'm going to consider this a homework problem and give a limited answer.

    Certain parameters are common across all logic chips within a "family" such as LS, HC, HCT, etc. and can be found in other documents besides the datasheet.

    Your datasheet has both a chart of absolute maximum current values and a mention of the number of logic device loads that it can drive by type (fanout).
     
  3. crutschow

    Expert

    Mar 14, 2008
    12,995
    3,229
    On the data sheet you referenced there are listings for the high level and low level output voltages for various supply voltages and load currents. From that you can calculate the minimum load resistance which can be connected to either the plus supply or ground, whichever is desired.
     
  4. KrisBlueNZ

    Member

    Oct 17, 2012
    111
    14
    That's right. Your lecturers are talking about a maximum load CURRENT, not a maximum resistance. "More" loading means more load CURRENT, not more load resistance.
     
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