LT3092 problem

Discussion in 'General Electronics Chat' started by djape, Jul 3, 2013.

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  1. djape

    Thread Starter New Member

    Feb 8, 2013
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    Hi everyone,
    I am trying to get stabille em field in inductor so what i need is inductor and some current source to drive that inductor.The inductor is wounded and have cca 2000 turns, which in this case isn`t so important.
    Problem i have in this case is with current source.I need stabile and constant current source, so i used lt3092-programmabile cs which is capable to produce up to 200mA. Several of them connected parallel will produce, or should produce larger current equal to summary of current each of them produce.And that is what is this "thing" doing. But during in time, after several moments current which LT3092 is producing suddenly starts to drop.It is not constant any more and also magnetic field in inductor also drops.I have tried to substitute inductive resistance with equivalent resistor and the same thing is happening.
    I have several of lt3092 and tried them on external board.On the start current they produce is stabile and gets rapidly low after several moments.I used two resistor configuration to set desirable current, which is available in datasheet.Current each of them produce is 180mA.
    Does anyone have some idea about this or from yours experience with this ic`s?
    Thanks
     
  2. LDC3

    Active Member

    Apr 27, 2013
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    What is the input and output voltage?
     
  3. djape

    Thread Starter New Member

    Feb 8, 2013
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    Supply is adjustable between 12-36V.
    Output current is set to 186mA at 35ohms output voltage is about 8.6V.
    Do you think that there is problem with power dissipation and overheating device?
     
  4. LDC3

    Active Member

    Apr 27, 2013
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    If you are using 36V, I'm certain there will be a heat problem. If you are using 12V, it should be fine, although it might get a little warm.
     
  5. djape

    Thread Starter New Member

    Feb 8, 2013
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    I have decreased supply to 15V and when supply them from external power supply they dont stop working but when i connect them on transformer via voltage regulator on the same voltage (15.5V) current is decreasing, as it was before with greater voltage.
    Circuit is behaving different on 15V when are connected on power supply and on transformer.
    Power of transf. is 50 VA, while total consumption of power is about 10W of LT3092, plus the power disipation on voltage regulator.
    Transformator is 230V/30V, and after capacitor there is 42V; so the disipation on voltage regulator is (42-15)*I=25*(~1A)=20+W
    Power of transformer is sufficient for all power losses in circuit..
    Now i am confused why is there difference between supplying from external power supply and from transformer?
     
  6. Plamen

    Member

    Mar 29, 2015
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  7. Papabravo

    Expert

    Feb 24, 2006
    10,178
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    Is there a question you want to ask on this two year old thread?
     
  8. ScottWang

    Moderator

    Aug 23, 2012
    4,856
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    Hello Plamen:
    If you have any questions, please start a new thread, this thread will be closed.
     
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