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CD4060B: Design Guidelines for Pierce oscillator section (fig. 13 of datasheet)

Part Number: CD4060B

Hi,

Fig. 13 (“Typical crystal circuit”) gives a design equation to size C1 and C2 with respect to Cload, but ignores Rc and Rs.

May I get the appropriate design guidelines for these resistors? (in a couple of applications, I would like to set the CD4060 ic with 4 to 9MHz crystals powered by 5, 9 or 12VDC supplies).

Thank you for your kind help!

ARB

  • Hi ARB,
    First, just FYI, this device is very old and was designed and produced by Harris Semiconductor, then acquired by TI, so the info you have on the datasheet is the same info we have on it.

    This image is provided as an example of common applications for this IC, however we don't provide extensive design details because oscillators are complex -- some people make entire careers out of oscillator circuits.

    I would recommend prototyping the circuit you want on a PCB -- I know a few places that you can get one made for just a few dollars (although I can't recommend any as a TI employee). I would starting with a small capacitor in the Rs location since you want to work at a relatively high frequency (> 4MHz) and test different resistor values in Rc. I would recommend values for Rc between 500k and 5Meg -- I believe that the feedback resistor value is generally not that important compared to the crystal's capacitors, which should be designated in the crystal datasheet.

    Hopefully this helps some, and good luck with your project!