Hi forum.
I know this arguments has been treated many times inside this forum but since I needed for my circuit that runs on 24Vdc and has a 3A max current draw, I was searching the internet to find a voltage reverse voltage protection and I crushed into this schematic that is a protection (VCC_SEC) for the LM2596 simple buck converter with an output of 5v 4A for an input between 5v and 15v. (VCC) "The board - claims - also has a polarity inversion protection, over tension and over current / short circuit protection tested with laboratory equipment."
Here the link:
https://oshwlab.com/anonymousse_1/buck-12-5-test
Here the schematic:

What I do not understand is apart from the Q5 P-MOSFET and the R31 and D15 that forms reverse polarity protection and is relatively clear to me, and the F2 resettable fuse how the other parts are used to.
My goal is to adapt the circuit for having nominal input 24V (maximum 26Vdc) and all the stuff protection claimed into the previous schematic.
I am going to use LTspice to simulate the proposed schematic and understand what is going on and will post it when ready.
For now thank You all.
Steve

 

So you want the over-tension, over-current /short-circuit protection as well as reverse polarity protection (?).

 

Yep,if possible. At least would like to understand how it works in order to implement it. thanks

 

I don't see any overcurrent sensing. There's an assumption that the input is Vcc and the output is Vcc-sec. The
overvoltage check prevents overvoltage on Vcc from getting to Vcc-sec. This works by having Q7 turn on on
overvoltage (gate stays down but source rises with input voltage). Q7 then pulls Q6 get up turning Q6 off.

It helps to put things right side up with the most positive line at the top: Vcc - Q5 - <lots of space> - Q6 and grounds
at the bottom. Then put D1 R33 R32 D1 below along with Q7.

 

I don't see any overcurrent sensing.

It apparently has over-current/short-circuit PROTECTION. I suppose that is the purpose of F2.