TL5001 external reference?

The TL5001 internal reference is applied directly to the non inverting error amplifier input.  If you wanted to use an external reference, you would need to implement an external error amplifier.  i would probably then set up the internal amplifier as a unity gain follower.  there are other devices such as TPS54672 that have a tracking function where you can apply an external reference that will override the internal reference.  What are your Vin, Vout and Iout requirements?

Thanks for your answer. Vin would be fixed from a 24VAC transformer (~35VDC after rectifier, no load). Vout should be about 4 to 30V. Iout is variable from 0 to 5A (10A if realistic?)

I would like to implement this with TL5001 since it's a small project and i have a few of these around.

If you are just trying to make a variable output supply, then you can change the output voltage by using a potentiometer for the lower leg of the feed back resistors.

Yes, but I'm not using a potentiometer in this project. I would like to set up the voltage with a microcontroller (use a DAC as a voltage reference).

What I'm thinking to do is something like this: 

My rationale is that this will make the transistor "rob" current from the FB pin, enough to nudge the output a little.

The more current the transistor is drawing, the higher the output voltage. When it's fully saturated, it will only be limited by R2 (this will limit the output voltage to 1+R1/R2). When it's not conducting, the output will be 1+R1/infinity = 1+0 = 1V.

Is this correct?

that would be one way to do it.