ULN2003 paralelling help!!!!!

Discussion in 'The Projects Forum' started by DudeDude22, Apr 9, 2012.

  1. DudeDude22

    Thread Starter New Member

    Apr 9, 2012
    2
    0
    I am seeing on many data sheets and websites that you can parallel the output of the chip for higher current. I need this higher current for a stepper driver I am working on. Here is the wiring that I am using: http://electronics-diy.com/stepper_motors.php how could I parallel the output going to the motor without blowing the chip as they have a 500ma limit.??? :confused::confused::confused::confused::confused::confused:
     
  2. R!f@@

    AAC Fanatic!

    Apr 2, 2009
    8,754
    760
    If you are seeing then why can't u get a diagram to do it ? :cool:

    My advice is to drive a stepper that chip can handle.
    If the stepper needs more current try using a chip that can handle that load or use transistors to drive the stepper.

    It is easier that way.

    To parallel a 2003 out put, u should see it's data sheets and study it before attempting. First rule is understand the chip tht r working on.
     
  3. DudeDude22

    Thread Starter New Member

    Apr 9, 2012
    2
    0
    I have looked at many data sheets and they all say, the output can be paralleled for higher current, but they don't say HOW to do it. HOW can I do it.
     
  4. jimkeith

    Active Member

    Oct 26, 2011
    539
    99
    Since these chips are cheap (US 0.55 each), I would dedicate a chip for each of the 4 outputs--simply bus all 7 inputs together and all all 7 outputs together--one unknown (to me) is how much drive is available from the parallel port.

    Note that in this app, there is no PWM control of current so the applied voltage may not exceed the stepper motor voltage rating--in other words, the current is controlled by the applied voltage ÷ winding resistance--this will work great at low speeds.
     
  5. Felo

    Member

    Feb 20, 2012
    91
    13
    Hi, I once paralled a 2003 simply by "piggybacking" it, worked but I would not recomend for any serious application. besides it looks awfull to see a couple of IC's "getting it on" in front of all the other components. hehehe
     
  6. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    You either need a more capable Darlington array, or you need to go to a different technology switch, like MOSFETs.

    Have a look at the ULN206x Darlington arrays:
    http://search.digikey.com/scripts/DkSearch/dksus.dll?x=0&y=0&lang=en&site=us&KeyWords=ULN206
    And the ULN207x Darlington arrays:
    http://search.digikey.com/scripts/DkSearch/dksus.dll?vendor=0&keywords=ULN207
    They're more expensive than the ULN2003's, but can handle several times the current.

    MOSFETs are a significant improvement, as there will be little voltage drop across them, whereas a Darlington will always lose a minimum of 0.63v across the collector/emitter junction, even at low collector currents. The voltage drop can go up to 1.6v or even more at high current. This means lots of power dissipation as heat in the Darlington.
     
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