voltage controlled current source

Discussion in 'General Electronics Chat' started by mindbomb, Mar 14, 2009.

  1. mindbomb

    Thread Starter New Member

    Mar 14, 2009
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    Hi

    What is the simplest and best way to design a 0 to 5V voltage controlled current source for a stable 0 to 400mA output on low pure resistance loads (<5 ohm)?

    Thanks
     
  2. Ron H

    AAC Fanatic!

    Apr 14, 2005
    7,050
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    Does the load have to be grounded?
    What supply voltages do you have available?
    How accurate does the voltage-to-current transformation need to be (%)?
     
  3. mik3

    Senior Member

    Feb 4, 2008
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    An op amp with its output buffered by a transistor and your load placed in the feedback loop.
     
  4. mindbomb

    Thread Starter New Member

    Mar 14, 2009
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    Yep, I think the load has to be grounded, but I will be double-checking this tomorrow. I have a 5V supply available, and the transformation needs to be with 1mA precision at the output..

    any ideas?

    thanks!
     
  5. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
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    This IC Shows schematics for using a precision voltage source as a precision current source or current sink. Output is only 110mA using the the precision voltage source, but other op-amps/transistors could be used as mentioned above.
     
  6. mindbomb

    Thread Starter New Member

    Mar 14, 2009
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    first- thanks!
    second -
    should I combine (cascade) 4 of these to achieve maximal 400mA output or just change the transistor/resistor combination to a more wattage capable selection to achieve my target?
     
  7. mindbomb

    Thread Starter New Member

    Mar 14, 2009
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    0
    third - also for achieving a 1mA precision I will probably need to combine another low output current, high precision unit in parallel (since these units using maxim DS4303 have a minimum 10mA output)
     
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