I'm currently designing a short circuit detection circuit for a bench lab PSU.
When the PSU's output goes above 1.5A the short circuit detection circuit will disconnect the load from the output and latch so until the load has been removed.
This is my current circuit:
Basically I pass the output through a 1Ohm power resistor and feed the voltage on both sides of the sense resistor into an op amp in differential configuration. After that the output of op amp 1 goes into the non-inverting input of a second op amp that is configured as a comparator against a reference voltage adjusted by a pot .
The problem is that op amp 1 is not working as it should and I think the issue might have something to do with the grounding.
The op amps are supplied by a separate 12V supply but the two voltages going into the differential op amp are referenced to the PSU ground.
Is it ok to feed in voltages that are referenced to a separate ground?
My question might sound a bit obvious to some people but I'm really not sure what the issue is.
All help is welcome
When the PSU's output goes above 1.5A the short circuit detection circuit will disconnect the load from the output and latch so until the load has been removed.
This is my current circuit:
Basically I pass the output through a 1Ohm power resistor and feed the voltage on both sides of the sense resistor into an op amp in differential configuration. After that the output of op amp 1 goes into the non-inverting input of a second op amp that is configured as a comparator against a reference voltage adjusted by a pot .
The problem is that op amp 1 is not working as it should and I think the issue might have something to do with the grounding.
The op amps are supplied by a separate 12V supply but the two voltages going into the differential op amp are referenced to the PSU ground.
Is it ok to feed in voltages that are referenced to a separate ground?
My question might sound a bit obvious to some people but I'm really not sure what the issue is.
All help is welcome