I'm trying to make a couple of mains isolated, transformer based, bench power supplies. Considering that the current sense resistor will be in the PSU box and external loads will not have access to the other side of the sense resistor, does it matter whether current sensing is done high side or low side? Also, if low side, ground for all components (including op amps) in the PSU will be between the sense resistor and rectifier bridge.
Will it matter if I have a couple of these power supplies and connect the external grounds together? Will it matter if I put two of them in series (external ground of one connected to positive rail of other)? Ground is just a reference, right? So it will not lead to more noise or anything...?
I will have a short circuit protection based on output voltage.
[ edit: here's a proper schematic. I'm not showing the voltage sensing, but it will be there. The simulation works. However, the question remains. Any problems with low side current sensing in a benchtop PSU?
Also, I tried to simulate high side current sensing, and although the simulations work, I think it is violating input voltage range, so not sure I want to go there right now....
This simulates fine, current limit is set to 200mA, and 200mA flows into 100Ohm load (output voltage is at 20V). However, input at U1 is around 10.6V, higher than 5V supply. The simulation gives wrong results, as it should, if I remove the 1V offset. But I cannot understand how the offset helps overcome input voltage range limitation.