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Quad buffer / line driver tri state circuit test rig

Discussion in 'General Electronics Discussion' started by Experimentalist, May 20, 2016.

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  1. Experimentalist

    Experimentalist

    3
    0
    May 18, 2016
    Hi

    Since nobody seems to have any suggestions regarding my other post Baffled - Please help - Quad buffer / line driver tri state circuit issue I am looking for guidance as to how I may be able to build a reliable test rig to test the 74HC125N channel by channel so that I can check my hardware.

    My chips are Phillips branded and have the following markings:

    74HC125N
    BA427 01
    UnG0624D

    Currently I plan to power the chip at 3.3V between ground and VCC, tie the 3 unused "output enable inputs" to ground and use a 10K pull up on the "output enable input" for the channel under test. This will be the only component so I guess there is little point but I was going to put a 100nF decoupling capacitor as close as possible to VCC for good measure.

    What should I use for the data input and how can I reliably check the data output? I do now have an oscilloscope but virtually no experience using it as yet.

    I have attached the chip data sheet for reference.

    Any guidance gladly received.
     

    Attached Files:

  2. AnalogKid

    AnalogKid

    2,498
    718
    Jun 10, 2015
    The link in post #2 is to an intentionally incorrect circuit, not sure what it is supposed to teach the OP.

    OP - you don't say what you are testing for. Input transition levels, input currents, output voltage levels, output impedance, output currents, bandwidth, logical functions, etc. Also, are you trying for in-circuit testing, or are these stand-alone devices?

    ak
     
  3. Experimentalist

    Experimentalist

    3
    0
    May 18, 2016
    I am just trying to prove the devices function correctly. The whole issue is explained in my first post, also linked above. I am using the device to overcome a well known fault in another device where it does not tri state its MISO pin on the SPI bus. I think the SPI clock speed is 22MHz.

    I am trying to test it stand alone so as to understand the issue I explain in the other thread.
     
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