ULN2003 Enable

Discussion in 'General Electronics Chat' started by JK-FlipFlop, Jul 3, 2011.

  1. JK-FlipFlop

    Thread Starter Member

    Jul 5, 2010
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    HI,

    I am using uln2003 for my matrix display project, and I need to find out a way to enable/disable it, this chip does not have enable (cs) pin so I cant multiplex it with others. Do you have any idea how to do it?

    or you can find me something equivalent to the uln2003 but with enabe pin, I didnt found anything.

    http://www.datasheetcatalog.org/datasheet2/f/0c6x6a46ig46qlxf3j2qsaii8o3y.pdf

    Thank you.
     
  2. lightingman

    Senior Member

    Apr 19, 2007
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    22
    The ULN2003 is really only a driver. You can OR the outputs but there is no enable.

    Daniel.
     
  3. Kermit2

    AAC Fanatic!

    Feb 5, 2010
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  4. SgtWookie

    Expert

    Jul 17, 2007
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    Well, perhaps you could use an N-ch logic-level MOSFET to interrupt the GND pin connection. If Vgs=0 on the MOSFET, then there would not be a direct ground path for the Darlingtons to sink current to; as long as the ULN2003's common cathode were either disconnected or connected to the +V supply.
     
  5. JK-FlipFlop

    Thread Starter Member

    Jul 5, 2010
    111
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    Thank you,
    I really thought about using MOSFET to turn off the chip, but are you sure that there isn't anything else equivalent? but with enable...

    I prefer using one with enable pin built in.

    for debugging I will use the mosfet switch meanwhile.
     
  6. SgtWookie

    Expert

    Jul 17, 2007
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    It would help if you would post your schematic and theory of operation.
     
  7. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    Add a cheap 1N4148 diode to each base input pin.

    Then the cathodes of the diodes are all connected together, let's call that point A.

    When you ground point A it ties all the bases to 0.7v so all drivers in the IC will be off, as they are darlingtons and need about 1.2v to turn on.

    Depending on what you are using to drive the bases you might also need a series resistor on each base pin.
     
  8. minhle

    New Member

    Jun 1, 2011
    6
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    as mensioned above, 2003 is a driver, so you need cd4017 so that it can drive 2003. the 4017 has a reset pin.

    hope it can help
     
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