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Current Source Op-amp

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leoren_tm

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Hi all.
I need Op-amp to be a current source of around 1ma-20mA. from the net found some LMC6462, unfortunately i do not have the parts, any possible replacement?

also if it will be digitally controlled, any basic suggestion on how to do this? maybe PWM?


thank you
 

Assuming you don't need any significant speed, any unity gain stable rail-rail opamp should do. Just vary the input voltage with a DAC to set the current.

Keith.
 

oh.. i mean i do not have LMC64626. i was asking for any possible replacement that could source current of up to 20mA,
 
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    tlusin

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use LM324 with the configuration mentioned by Keith, it works.

the above design is independent of opamp current capability...

Constant currnet(thru R2) is given by equation: I=V1/R1;

If V1 is from DAC o/p then it can be varried accordingly...


--babesh
 

tested on 324 and works just needed thanks i was just wondering as LMC6462 feature include current source, which i was thinking it was ideal to use, and replacement on it would be best to use, but with my simple application 324 is ok :)
 

now my output is unstable, i am using potentiometer on input side, but its not linear, anyway to solve this? already added capacitors
 
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    tlusin

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Could you post the circuit you are using? What load are you driving?

Keith
 

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