Voltage comparator circuit is an example of open loop configuration of Op-Amp. The input signal is applied to the non inverting terminal of the op amp. The reference voltage applied at the inverting terminal of the op amp.
If Ein > Vref then output of the comparator = +ve supply voltage.
If Ein < Vref then output of the comparator = -ve supply voltage.
In our project, Ein = input signal
Vref = 0.45 volt.
+ve supply voltage = +5V
-ve supply voltage = ground.