ULN2003 Darlington Array Connections

Discussion in 'General Electronics Chat' started by jack33, Jan 7, 2011.

  1. jack33

    Thread Starter Active Member

    Dec 31, 2010
    I'm using a ULN2003A to drive some LED displays, no inductive loads. Is there any reason to use the reverse EMF protection diodes? If not, can I just leave the Com pin unconnected?

    Also, I read that the unused inputs should be connected to ground. Is it OK to connect them directly? There is a built in 2.7k resistor on the inputs. Also, can I leave the unused outputs unconnected? The data sheets I have don't address these questions.

    Here's a more general question re unused IC pins:
    I have read a huge amount of material about unused IC pins, but I still find the subject a bit confusing. I've tried to digest all the different information and compile a list of general rules, but I have trouble sorting out all the apparent differences of opinion. I don't have enough in-depth understanding to form my own opinions. Can anyone recommend a comprehensive, definitive article on this subject?

  2. Markd77

    Senior Member

    Sep 7, 2009
    You can leave com unconnected.
    Connect unused inputs directly to ground, outputs unconnected.
    jack33 likes this.
  3. SgtWookie


    Jul 17, 2007
    You can use the COM terminal as a test function. Grounding COM will cause all of the outputs to sink current.
    jack33 likes this.