Switching Lab supply design

[Alakis]

Hello,

I am in the process of designing a programmable 0-24V, 0-3A lab supply. I am planning to drive it from an existing 12-48V DC supply. I would like it to be a small form factor so I am thinking about a switch mode topology. I am a little bit confused on how to pick the inductor sizing for such a wide parameter range. Are there any simple to understand reference designs I could take inspiration from? Ideally they would have some sort of explanation attached to them as well.

What I have planned so far:

1) Input buck-boost converter taking input voltage and converting it somewhere near 24V (maybe a little more to adjust for possible drop out)
2) CV part of the circuit, which I still haven't worked out well. I would take a reference voltage as input to convert the 24V to some desired level.
3) CC part of the circuit, similar to the CV part, just controlling the max current.
4) Current and voltage feedback would be done by some simple opamp circuits. For that, I am planning to add a split rail SMPS circuit. (something like here: https://www.digikey.at/de/articles/design-tips-for-generating-split-rail-power-supplies)
5) I am planning on using an INA219 or some other IC to read the output voltage and current, this would be separate from the CV and CC mode monitoring, as I don't want to rely on MCU response time for controlling the output.
6) MCU to communicate with PC via USB, display output values and control reference voltage DACs.

I am mostly confused and need guidance on the CC and CV parts. As I said before, switch mode component values change a lot depending on the output voltage and current. The reference designs always seem to be some crappy LM317 circuits, which work better as heaters than power supplies I would like to design something more efficient and without giant heatsinks.


Thank you in advance!

[LinuxHata]

Here you go, use this circuit as basis for your design.

[Gyro]

The OP double posted here...  https://www.eevblog.com/forum/projects/switching-lab-supply-design/  which now has more replies.

@OP Please don't double post, it annoys people through duplicating each others' replies, and ultimately gets you banned.

[coromonadalix]

while it is a good schematic provided earlier,   do note it doesn't provide any isolation

it act like a buck boost / buck down converter,  you will need an x-former  with filtering caps etc ...

[coromonadalix]

and you double thread  ... not nice

[Simon]

https://www.eevblog.com/forum/projects/switching-lab-supply-design/msg5319897/#msg5319897

Please don't double post