Digital control, but not really regulation, might be possible, BUT looking at the basic feedback system loop, the delay due to software will be much greater than the forward speed of the control. Thus instability is assured.
Take the advice in post #20 seriously, it is very good advice.

 

The microcontroller might manage it, but will your software?
Have you read and understood Network Analysis and Feedback Amplifier Design by Hendrik Bode?
How well do you understand digital signal processing? How well do you understand how to control the phase response of the feedback loop? Do you understand the Nyquist criterion for stability, as well the Nyquist's sampling theory?
And why would you want to spend £34 on the Infineon XMC4500 Relax kit when a UC3842 costing 34p would do the job?

I had the microcontroller, thats why i used it. I don't understand much about digital signal processing, but will i need all of this?
Can´t i simply provide a certain pwm signal to the mosfet, so that it gives me a constant output with a variable power supply?

 

I had the microcontroller, thats why i used it. I don't understand much about digital signal processing, but will i need all of this?

Yes.
https://www.ti.com/seclit/ml/slup340/slup340.pdf
This is what you are trying to implement digitally. Note that the phase and amplitude responses need to be well controlled up to about 1MHz, and what is the phase response of your anti-aliasing filter going to do to it?

Can´t i simply provide a certain pwm signal to the mosfet, so that it gives me a constant output with a variable power supply?

Yes, you could use a feedforward technique (although you could probably manage that with a 555), but the relationship between duty cycle and output voltage falls apart when the operating mode changes from continuous to discontinuous.
If you can manage to keep it in continuous current mode (i.e there is a permanent load), it would work.
[Edit] then you wouldn't need to measure the output voltage, so that would save the inverting op-amp.

 

Yes.
https://www.ti.com/seclit/ml/slup340/slup340.pdf
This is what you are trying to implement digitally. Note that the phase and amplitude responses need to be well controlled up to about 1MHz, and what is the phase response of your anti-aliasing filter going to do to it?

Yes, you could use a feedforward technique (although you could probably manage that with a 555), but the relationship between duty cycle and output voltage falls apart when the operating mode changes from continuous to discontinuous.
If you can manage to keep it in continuous current mode (i.e there is a permanent load), it would work.

But the purpose is to use it in continuos mode only.

 

But the purpose is to use it in continuos mode only.

In which case, you must keep a minimum load on it. If the load is disconnected, the output voltage will keep increasing until something fails.

 

In which case, you must keep a minimum load on it. If the load is disconnected, the output voltage will keep increasing until something fails.

And keeping a load, don't you think i can just validate a buck-boost controlled by a microcontroller?
I ask this because i've seen buck/ boost converters being controlled by microcontrollers, thats why i think it's possible, but i'm not disregarding what you said (and the use of UC3842 ), the problem is that it seemed a bit complicated to me compared to the use of a micro.
Also, can i use the UC3842 to get the voltage i want at the output? Or it's made just to a single output voltage value?

 

Understand that regulated switching power supplies are really rather complex, even if that circuit does not seem so complex. Check the TI website for information on switchers and see what they have to say. And there are other companies that also have extensive tutorials on switchers. And because these places have a serious interest in circuits with their products working well, you get good information, far more useful than anything on yootoob.