use of darlington array

Discussion in 'The Projects Forum' started by bhageria, Jun 3, 2011.

  1. bhageria

    bhageria Thread Starter New Member

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    Jun 3, 2011
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    Hello...

    can anyone please explain me how to connect a uln2003 darlington array between ic 4017 an LEDs? please...
  2. SgtWookie

    SgtWookie Expert

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    Basically like in this schematic:

    [​IMG]

    The ULN2804 is similar to the ULN2003, but it has 8 Darlington channels instead of 7 channels (so the pin numbers will be different after the 7th Darlington channel), and it has 10k resistors on the inputs instead of 2.7k like the ULN2003.

    Since you are using the 2003 instead, you really should use 7.5k Ohm resistors between the 4017 outputs and the 2003 inputs; otherwise your 4017 outputs will be sourcing more current than they are specified for. You might "get away" without adding the resistors, at a penalty of decreased reliability.

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