Current Source Op-amp

[leoren_tm]

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

 

[keith1200rs]

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.

 

[leoren_tm]

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

 

[BABESH]

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

 

[leoren_tm]

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

 

[leoren_tm]

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

 

[keith1200rs]

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

Keith