Micro215
Newbie level 2
I'm trying to get a complete understanding of a schematic I've been given. On a high level, I got it. It's a portable reusable "fuse" that you can hook in-line in a circuit with the potentiometer setting up the threshold for what current level will trip the device. When the switch 2 is set to connect pins 4/5 and 2/3 it'll only notify you of high current running through input 1 & 2 by D6 turning off. When the switch is set to 5/6 and 1/2, current above the threshold will turn on the transistors which will shut the MOSFETs off and disable any current flow at the inputs.
What I can't quite figure out though is calculating the voltage level seen at pin 2 of the op-amp. Looking at an ideal analysis, it should just be input current x .22 Ohm since no current would flow into the collector for a transistor in cut off mode or into the input of the op-amp. But that produces a voltage level too low to actually trip the device. I'm hoping someone with a lot more practical knowledge than me can help me out on this.
What I can't quite figure out though is calculating the voltage level seen at pin 2 of the op-amp. Looking at an ideal analysis, it should just be input current x .22 Ohm since no current would flow into the collector for a transistor in cut off mode or into the input of the op-amp. But that produces a voltage level too low to actually trip the device. I'm hoping someone with a lot more practical knowledge than me can help me out on this.