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TL783: I have a question about TL783 Current-Sinking Regulator.

Bob Lee62837
Mastermind 7230 points
Part Number: TL783
Other Parts Discussed in Thread: TPS75105

Dear Kyle Van Renterghem and support member,


Because I can not reply the previous, I new post.

My customer made board of TL783.
My customer make six parallel schematic Fig16 Current-Sinking Regulator.


I have a question.

Is there a way to control device variance by adding external configuration?

Best regard.
Bob Lee.

  • 0
    TI__Expert 6895 points
    Hi Bob,

    Would you be able to provide more information on what you are looking to control? If you are looking to control the current the simplest way would be to use an adjustable resistor between ADJ and OUT. This would allow for a quick adjustment of the output current.

    Best Regards,
    Mark
  • 0 in reply to Mark Sellers
    Mastermind 7230 points

    Dear Mark Sellers,

    Thank you very much for reply.

    The configuration was described in the attached file.

    Could you check attached file?

    Best regard.
    Bob Lee.

    TL783_Question.pdf

  • 0 in reply to Bob Lee62837
    TI__Expert 6895 points
    Hi Bob,

    Thanks for the file. Would you be able to give us some more detail about the current you were expecting and the current that you got? Did you measure the current through each regulator individually? If so was there a single regulator that was drawing much more current than expected?

    Would you also be able to provide a plot of the Out pins of the regulators and the current for each?

    Best Regards,
    Mark
  • 0 in reply to Mark Sellers
    Mastermind 7230 points

    Dear Mark Sellers,

    Thank you very much for reply.

    I designed that LED total current is 0.7 A.
    But I measured 0.71A.


    The resistance of TL783 is 10.8Ω,and I considered 0.117 A for each IC.
    （LED total current is 0.117A x6 = 0.7A）


    Even if each current is measured, it changes every time.

    Is there a way to control by adding external configuration?


    Best regard.
    Bob Lee.

  • 0 in reply to Bob Lee62837
    TI__Expert 6895 points
    HI Bob,

    I am not aware of an easy way to do this externally. You are already getting 1.4% accuracy, which is well within the tolerance of the system if you are using a 1% resistors and a 1.5% LDO.

    You could try another part the TPS75105 this is designed to be a LED driver and it may fit your application better.

    Regards,
    Mark
  • 0 in reply to Mark Sellers
    Mastermind 7230 points

    Dear Mark Sellers,


    Thank you very much for reply.

    May I ask a question?

    Your answer was replied as 1.5% LDO.
    Where it descript in the data sheet?


    Best regard.
    Bob Lee.

  • 0 in reply to Bob Lee62837
    TI__Expert 6895 points

    Hi Bob,

    The  accuracy is covered here. Your application may actually be at the 0.5% accuracy as you are using less than a 5V output. Hope this helps.

    Best Regards,

    Mark

  • 0 in reply to Mark Sellers
    Mastermind 7230 points

    Dear Mark Sellers,


    Thank you very much for reply.

    I tell my customer your addvice.
    I will feedback you.


    Best regard.
    Bob Lee.