I am looking to make a comparator using transistors and I stumble across this circuit claiming to be one:
Unfortunately, the description that came along with it leaves a lot to be desired, referencing components and points that aren't actually here – I assume due to typos but I can't actually work out how it is meant to work.
The purpose for this is I want to have a voltage reference of 1.8 – 2V, and then a supply rail connected to the other side. So long as the supply rail is higher than my reference voltage, it will allow power to be supplied to a component, but if not, it should remove power from it.
Any thoughts as to how this works and whether it is suitable for my application? Diagrams would help me to understand it more but any help would be appreciated.
I want to use this 'comparator' in a circuit where I have a \$\mu\$C being powered by a current limited ~2V regulator. Currently, if the voltage output of this regulator drops below 2V the \$\mu\$C causes the rail to latch at 1.7V – 1.8V and won't allow it to rise to 2V again which is a bit of an inconvenience if anything. (How can I get this PMOS to turn off? is another question of mine which contains more information on the issue I am currently having)
I currently have a delay switch that will allow my reservoir capacitor to fill enough to be able to handle the initial start-up current of the \$\mu\$C. There are some problems with this and I just thought I might be able to replace it with a simple comparator, have a ~2V reference on one pin and the rail to the \$\mu\$C on the other and if this falls below my reference, it will simply cut off the power completely – this will prevent it from latching at ~1.7V and will allow the reservoir capacitor to fill up again in order to provide the needed start-up current again.
It isn't something that would happen a lot, and realistically, once fully designed and programmed, the circuit would never cause this rail to drop below 2V – however, there are some circumstances that might cause it to happen so it is a 'just-in-case' type thing.