How to make a constant DAC controlled current source using LT3092

[newbie_hs]

I am trying to make a constant current source using LT3092 .My DAC maximum output is 3.3V and at that time the current source needs to generate a current of 20mA.
For generating 20mA the RSET(R1 in schematic) value needs to be 165 Ohm . Please see my circuit below.

The issue what I am facing is my load will come in series with RSET and this is changing thedesired current.May I know is there any way to solve this issue.
Below is the circuit with load.You can see that the current is changed.

Is there any way to make a DAC controlled constant current source using this IC

 

[KlausST]

Hi,

I personally would not do it. Because the IC is designed for an R to set the current.

Your text gives no requirements: Your schematic shows:
* 5V supply
* high side operation (true current source)

If it is for 20mA only what is the DAC used for?
I can only guess: You want the current source to be adjustable ... but what range?

But what output voltage range do you need? (or what is the max allowed dropout voltage)
Any accuracy requirements, any load requirements, any requirement about settling time?
Is there a reason for using especially this IC?

Here a short tutorial how to design a DAC controlled High Side current source
(This forum has a search engine.... Free to use ;-) )

Klaus

 

[newbie_hs]

I read that article .I already made a design with the help of that tutorial.Thank you.

Later I saw this IC.Started experimenting.

My output current measurement is not only 20mA.

When the DAC output is 3.3V(Maximum DAC output voltage) I need to 20mA in my load.

I am expecting a character like this