programmable frequency divider circuit

Discussion in 'The Projects Forum' started by CaliusOptimus, May 4, 2007.

  1. CaliusOptimus

    Thread Starter Well-Known Member

    Aug 14, 2005
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    ive been trying to come up with a circuit that would allow me to use a decade counter as a 'programmable' frequency divider. what i mean, is to be able to input a bcd (or decimal, if necessary) number, and have the base frequency divided my that number (eg. divide by 0 through 9, 0 being no pulses sent). ive come up with an idea that seems to work fine, but it requires 6 discrete ICs. (i actually need several of these for one project, so 6 ICs each is a little excessive). ive posted a schematic of it so you can really see what im shooting for. flipping through digikey, i found the cd4522b, which sounds like it would work perfectly for my design, although 'not recomended for new desgns' is stamped on the datasheet. has anyone used this chip before? i dont need to order anything else right now, so doing so just for those would be a waste of time and money if they dont work for my application. any suggestions welcome!! thanks
     
  2. thingmaker3

    Retired Moderator

    May 16, 2005
    5,072
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  3. CaliusOptimus

    Thread Starter Well-Known Member

    Aug 14, 2005
    59
    0
    thanks! that's almost perfect for my project, considering it also allows me to connect a pair of 4511's without any decoding. i noticed it states that '1' on the inputs is an illegal state. do you happen to know what effect this has on the 'zero detect' output?
     
  4. thingmaker3

    Retired Moderator

    May 16, 2005
    5,072
    6
    If I'm understanding the datasheet correctly, there is no actual "zero." The counter runs from preset value down to 1 and then goes back to preset. Frequency division is the same as if it went from (preset-1) to zero. If preset is one, things should get stuck. Zero detect would probably always be in the same state - I don't know if such would be low or high.
     
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