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CD74HC4059: Creating a Frequency Divider

Gage Pelon
Prodigy 240 points

Part Number: CD74HC4059
Other Parts Discussed in Thread: CD4059A

Hello All,

At my job, I have motors that produce a large amount of pulses per revolution (360 PPR for example), and I'd like to cut that number down by a lot (down to about 1-6 PPR). I've managed to make a "Divide-by-5" using D Flip-Flops and a few logic gates, but now I am looking at the part number stated above. I'm under the impression that when using this IC, I can divide by virtually any number, within limits, but I'm having a hard time understanding the Data Sheet.

I would greatly appreciate some help with understanding the pins and what I need to design a circuit out of this IC.

Thanks in advance,

Gage

  • 0
    TI__Guru* 97676 points
    Hi Gage,
    I think this chip might be overkill for your application, but it is possible to make it work. The SN74HC4059 was designed to be pin-to-pin compatible with the CD4059A, which has a datasheet that is a bit easier to read and contains some examples.

    For your application, it looks like you want to divide by a number between 60 and 360. First, decide what you want to divide by, then you can follow my example here.

    I'm going to choose 60 to divide by:

    Ka = Kb = Kc = H, sets the device into mode "2" for the first counting section. 60 / 2 = 30 <- we will need that in a second.

    J1, J2, J3, J4 = 0 since our remainder is 0.

    J5, J6, J7, J8 = 0 since we don't need to divide by a 1's value

    The 10's value is '3', and 3 = binary 0011, so:
    J9 = 1
    J10 = 1
    J11 = 0
    J12 = 0

    J13, J14, J15, J16 = 0 since we don't need to divide by a 100's value
  • 0 in reply to Emrys Maier
    Prodigy 240 points

    Emrys,

    Thanks for the help! Your example made it pretty clear to me. I took the liberty of creating my own example, to ensure I understand this completely:

    Choosing N=15

    Ka=Kb=Kc=0 sets the device into mode "2". 15/2 = 7.5

    J4     J3     J2     J1

    0       0        0       1       since my remainder = 1

    J8     J7     J6     J5

    0       1        1       1       since my 1's place = 7

    J12     J11     J10     J9

    0          0         0        0       since 10's place = 0

    J16     J15     J14     J13

      0        0         0         0       since my 100's place = 0

    Is this all correct?

  • 0 in reply to Emrys Maier
    Prodigy 240 points
    Please see my reply below.
  • 0 in reply to Gage Pelon
    TI__Guru* 97676 points
    Hey Gage,
    For mode "2", Ka = Kb = Kc = HIGH (Vcc). Setting all three low will put you into the Master Preset mode.

    J1 J2 J3 and J4 get split depending on the mode between "decade 5" (the "first counting section" in the datasheet diagram) and "decade 1" (the "last counting section" in the datasheet diagram) -- something I didn't clearly show in my example above... sorry about that!

    In mode "2" - J1 is the only jam used for "decade 5", and since you are dividing by a value less than 1000, J1 = 0

    For a remainder of 1, J2 = 1, J3 = J4 = 0

    The rest of your values are correct.
  • 0 in reply to Emrys Maier
    Prodigy 240 points
    Hi Emrys,

    The K values were a misinterpretation on my part! I saw something about the decade 5 pin after I had posted it, but was unsure - thanks for the clarification! You've been a big help, I appreciate it.
  • 0 in reply to Gage Pelon
    TI__Guru* 97676 points
    Happy to help.

    I hope all goes well with your project!