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    replacing CL100 with ULN2803A

    Now i'm using CL100 with optocoupler to drive G2R2 12VDC relay.
    I'm trying to replace the CL100 and flyback diode with ULN2803A...
    Is this is correct method..?

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    Re: replacing CL100 with ULN2803A

    Hi,

    What is a CL100? Show the datasheet.

    If you want us to verify your idea you should additionally show us your schematic.

    Klaus
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    Re: replacing CL100 with ULN2803A

    If that is the same CL100, it can probably be replaced with a ULN2803A but there are factors to watch for:
    1. ULN2803A has darlington transistors so it has a higher turn-on voltage than a single BJT,
    2. ULN2803A has internal series base resistors, including a pull-down so make sure you can drive it.
    3. You waste 7 identical drivers unless you have other uses for them. (note they share the same diode pin).

    That last point about sharing the same diode pin is important, it should be connected the same way as your existing 'flyback' diode but you cannot use the other driver stages unless they also run from the same voltage.

    Brian
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    Re: replacing CL100 with ULN2803A

    Click image for larger version. 

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    The Relay is 12VDC power supply..The driver IC is ULN2803A
    Is this circuit is correct..?



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    Re: replacing CL100 with ULN2803A

    Hi,

    It looks okay to me. Maybe worth considering if internal 2k7 is sufficient/~4mA is actually needed as base drive current, maybe there's some info in the datasheet saying e.g. ~1.5mA is max. for 3.85V in, by extension might be worth considering upping the 470R to ground value by a couple of orders of magnitude. I suppose optocoupler LED input voltage bears appropriate relationship to the 470R there.



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