Replacement for unavailable chip

Discussion in 'The Projects Forum' started by MikeKulls, Apr 4, 2016.

  1. MikeKulls

    Thread Starter New Member

    Apr 4, 2016
    5
    1
    I am trying to build a circuit I found online, I'm no expert so I like stuff where the functionality is packaged into a chip of some sort. This circuit simply produces a square wave of 153.6Khz using a chip called exo-3 or exo-3c. The chip has an internal crystal I believe so will be accurate. I cannot find this chip available anywhere (digikey, farnel, jaycar etc) except ebay from the US but postage is expensive. I can hardly find any mention of it on the internet. Is there a replacement for this chip? Is there a simple way to produce 153600Hz squarewave that will be accurate?

    Circuit is here, the clock generator is very simple, only the exo-3 and 1 cap. (did I mention I like simple? :)
    http://pinoutsguide.com/images/nissan_consult_cable.gif
     
  2. dannyf

    Well-Known Member

    Sep 13, 2015
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    " Is there a simple way to produce 153600Hz squarewave that will be accurateaccurate"

    Yes. But what's simple to others may not be simple to you and vice versa.
     
  3. SLK001

    Well-Known Member

    Nov 29, 2011
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    It's just a crystal oscillator, with a frequency of 153.6 kHz. It most probably is a custom frequency and not a stock item. There is an 8 pin version by SEIKO on eBay right now that should work.
     
  4. MikeKulls

    Thread Starter New Member

    Apr 4, 2016
    5
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    Can you post a link? I might not be able to see it due to country.
     
  5. MikeKulls

    Thread Starter New Member

    Apr 4, 2016
    5
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    It doesn't need to be as simple as the original but would like something based on a crystal so it is accurate. Most stuff I search online is using 555 chip which I presume isn't that accurate because you can vary the frequency with a resistor.
     
  6. dannyf

    Well-Known Member

    Sep 13, 2015
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    Tons of "simple" solutions:

    1) take an oscillator at multiples of 153.6Khz and divided it down: 9.8304Mhz (=153.6*64) is a sonet oscillator and usually very accurate - typically within 1ppm.
    2) use a mcu.
    3) use a programmable pll oscillator.
    ...

    Again, without knowing what "simple" means to you, no one can be of more help to you.
     
  7. Lestraveled

    Well-Known Member

    May 19, 2014
    1,957
    1,215
    Go to Digi-Key and search for "Programmable Oscillators". Digi-Key will program them for you.
     
  8. dannyf

    Well-Known Member

    Sep 13, 2015
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    another example: 12.288Mhz is a very typical frequency, and it happens to be a multiple of 153.6Khz.

    The same for 4.9152Mhz, 19.6608Mhz, .....
     
  9. SLK001

    Well-Known Member

    Nov 29, 2011
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  10. hp1729

    Well-Known Member

    Nov 23, 2015
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    The frequency is standard enough. What kind of package are we talking about? Would you be open to a small board that plugs in to where the chip went?
     
  11. MikeKulls

    Thread Starter New Member

    Apr 4, 2016
    5
    1
    Thanks for all the replies. I ordered the SPG8650D, it couldn't get much simpler than that.

    Dannyf, I am curious to know how you would do it by dividing the frequency of an oscillator. If you could post something I would really appreciate it.

    Thanks again.
     
  12. MikeKulls

    Thread Starter New Member

    Apr 4, 2016
    5
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    So the SPG8650D arrived. Looking at the datasheet everything has pull-up or down resistors in the direction I need. So I just supply power and out comes 153.6khz. Couldn't get much simpler than that!! Thanks everyone for the replies.
     
    ErnieM likes this.
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