Constant current source using linear regulator.

[MalcolmB]

Hi all. The subject says it all. How do I use a linear regulator as a constant current source.
Thanks very much.

 

[danadak]

Not knowing your requirements, or compliance needed, or accuracy or....

we have a simple example -

Regards, Dana.

 

[crutschow]

Would help greatly to know your requirements so we can give a better answer.

 

[MalcolmB]

Hi Dana.
That will do what I want. The formula is very handy as well.

Best wishes

Malc

 

[MalcolmB]

Not knowing your requirements, or compliance needed, or accuracy or....

we have a simple example -

View attachment 137462


Regards, Dana.

Hi Dana
That will do fine. The formula is handy as well.
Regards
Malc

 

[crutschow]

That LM317 circuit has a voltage drop of about 3V when operating near the limit of the current-limit setting.

Is that okay for your application?

 

[MalcolmB]

Thanks for the reply.
That will be more than fine for my application.
Regards
Malc

 

[crutschow]

For your possible interest, below is the LTspice simulation of the LM317 circuit set for a 1A limit, with the output lead resistance decreasing with time until the limit is reached.

 

[danadak]

What your compliance range looks like -

Regards, Dana.