Programmable current source

Discussion in 'General Electronics Chat' started by johnkaz77, Sep 21, 2010.

  1. johnkaz77

    Thread Starter Member

    Sep 20, 2010
    33
    0
    I want a programmable current source/sink to provide me 0-10uA.(When a digital signal is '0' it will function as a current source,when '1' as current sink).Can anyone suggest something???
     
  2. tom66

    Senior Member

    May 9, 2009
    2,613
    213
    Use an op-amp as a current sink.

    Here's a circuit that will work (http://www.falstad.com/circuit to simulate.)

    Code ( (Unknown Language)):
    1.  
    2. $ 1 5.0E-6 10.20027730826997 50 5.0 50
    3. a 336 176 432 176 1 15.0 -15.0 1000000.0
    4. f 432 176 480 176 0 1.5
    5. r 480 224 480 288 0 1000.0
    6. g 480 288 480 304 0
    7. w 480 224 336 224 0
    8. w 336 224 336 192 0
    9. w 480 224 480 192 0
    10. L 224 160 192 160 0 1 false 5.0 0.0
    11. r 288 160 224 160 0 12000.0
    12. r 288 160 288 224 0 27.0
    13. g 288 224 288 240 0
    14. w 288 160 336 160 0
    15. w 480 112 480 160 1
    16. R 480 112 480 80 0 0 40.0 5.0 0.0 0.0 0.5
    17. o 11 64 0 35 0.13670317029893825 9.765625E-105 0 -1
    18.  
    It sinks around 11.2μA; tweak the resistors if you want to get a precise figure of 10μA.
     
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  3. johnkaz77

    Thread Starter Member

    Sep 20, 2010
    33
    0
    I saw that there is REF200 which can be used as current source/sink but i don't know how to connect it in order to provide me 0 to 10uA when a digital signal is '0' and -10uA to 0 when the signal is '1'.Here is the link to the datasheet if anyone can upload a circuit for 1.8V power supply. http://focus.ti.com/lit/ds/symlink/ref200.pdf
     
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