Problems using a EDE2208 for momentary/toggle

Discussion in 'General Electronics Chat' started by Blumpkinson, Jul 26, 2013.

  1. Blumpkinson

    Thread Starter New Member

    Jul 26, 2013
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    I'm using a EDE2208 IC to turn a signal from a momentary input into a toggle signal for my circuit. The IC works perfectly, the only problem I ran into was when powering up the circuit, the change in voltage from 0V to 5V activated the IC. I need the ouput signal to be zero until the button is pushed.

    Is there anyway I could isolate the start-up signal, so it wont activate the IC? Would there be a way to use a JK Flip Flop to get around this?

    Thanks guys
     
  2. Blumpkinson

    Thread Starter New Member

    Jul 26, 2013
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    Anybody have any ideas?
     
  3. Meixner

    Member

    Sep 26, 2011
    116
    21
    After searching for the datasheet there doesnt appear to be an easy way to do it. It seems crazy to me that the manufacturer didnt include a reset pin on the IC.
     
  4. Blumpkinson

    Thread Starter New Member

    Jul 26, 2013
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    Yeah, the reset function completely slipped my mind when making this circuit. Is there any easy/simple circuits that I could use to replace this particular IC?

    I say simple b/c i'm a Mech E and electronics is still pretty far out of my comfort zone.

    Thanks
     
  5. LDC3

    Active Member

    Apr 27, 2013
    920
    160
    Are all the unused inputs tied to ground?
    Do all the outputs start with a high signal? Maybe this is the default.

    If the outputs start either all high or all low, then connect your output and another one to a XOR gate so the signal always starts low.
     
  6. LDC3

    Active Member

    Apr 27, 2013
    920
    160
    From the datasheet:
    It looks like you have a faulty IC.
     
  7. Blumpkinson

    Thread Starter New Member

    Jul 26, 2013
    6
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    I'm only using one of the outputs, the other inputs are grounded. So when it's powered up only that output reads 5V, the other outputs go to ground. I've tried a few of the same ede2208 IC and they all have the same results.

    Any other ways around this?
     
  8. Sensacell

    Well-Known Member

    Jun 19, 2012
    1,132
    267
    The data sheet for the part says that it's supposed to reset on power up.

    I would make sure that the chip has a bypass capacitor really close to the pins, that might cure the problem.

    I bet the chip is freaking out because of the power on ramp is noisy or too slow?
     
  9. Blumpkinson

    Thread Starter New Member

    Jul 26, 2013
    6
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    So I may have found my problem. I am trying to have either a 5V powered momentary switch as an input or a momentary switched ground as an input. I am selecting between the two using a header.

    For the 5V powered momentary switch, the IC works fine. When I set it up to work on switched ground, is when I run into the problem. Any ideas on how I could get the switched ground to work?

    [​IMG]
     
  10. Blumpkinson

    Thread Starter New Member

    Jul 26, 2013
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    There is supposed to be a 5V source directly to the input after the button, which I forgot to put in the diagram.
     
  11. GroundZero

    New Member

    Jul 30, 2011
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    Hello, the spec sheet says you must have the unused inputs tied to ground not the outputs. The unused outputs should be left alone/not tied to anything.
     
  12. patlaw

    New Member

    Sep 7, 2010
    1
    0
    For historical purposes, anyone looking for an EDE2208 IC can find them as the PDN2208 at Paladin Semiconductors. They're just PIC processors, but it might be easier to buy one than to write the code for it.
     
  13. eetech00

    Active Member

    Jun 8, 2013
    650
    112
    Hi

    To use a ground input, try using a PNP transistor switch.
    See attached
     
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