Uln2003a

Discussion in 'The Projects Forum' started by alanjackson13, Jul 23, 2012.

  1. alanjackson13

    Thread Starter New Member

    Jan 14, 2012
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    I'm driving a 5V 30KHZ square wave through a ULN2003A via a pic output.
    The problem is the output of my ULN2003 switches from 5v down to 0.7v not 0V.
    Can any one tell me how to get it down to 0v. I am using 10k pull up resistors on the output
     
  2. #12

    Expert

    Nov 30, 2010
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    It is inherent that a saturated bipolar transistor will still have a few tenths of a volt across it. The ULN2003 uses a saturated Darlington pair and that makes it worse. If you want to get closer to zero, you must change to a MOSFET output, and I don't know a part number for that right now.
     
  3. ErnieM

    AAC Fanatic!

    Apr 24, 2011
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    2n7000, 2n7002,...
     
  4. #12

    Expert

    Nov 30, 2010
    16,252
    6,750
    That might work. Depends on the maximum current required. Half an amp with a 5 volt gate would make this one insufficient at 1.6 ohms D-S.
     
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