uln2803a circuit check

Discussion in 'The Projects Forum' started by bomrat, Jan 14, 2010.

  1. bomrat

    Thread Starter New Member

    Dec 13, 2009
    25
    0
    hi, i am building a circuit and i was wondering if i could run this by you guys.
    see if this is right?
    thanks
     
  2. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    Your SIP is simply adding MORE current requirement to the input.

    The ULN2803 has 2.3k Ohm resistors in series with each input.
    If your input is 5v, that will result in roughly (5v-1.2v)/2.3k = 3.8v/2.3k = 1.652mA current.

    Is that too much? If so, you need to look at a different technology.
     
  3. bomrat

    Thread Starter New Member

    Dec 13, 2009
    25
    0
    so this is what i want to do?

    thanks
     
  4. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    Yes.
    Is your PLC capable of sourcing 1.5mA at 5v?
     
  5. bomrat

    Thread Starter New Member

    Dec 13, 2009
    25
    0
    yes it is, its one of the cubloc controllers.
     
  6. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    You should be fine then.
     
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