VOLTAGE COMPARATOR ( LM 311)

Figure 1 : Datasheet of LM 211H or LM 311H

LM311 are voltage comparators that have input currents nearly a thousand times lower. This integrated controller (IC) is single high-speed voltage comparators. These devices are designed to operate from a wide range of power supply voltages, including ±15-V supplies for operational amplifiers.

Figure 2 : Voltage Comparator LM 311

By using the circuit of interface with high level logic with voltage comparator it is to maximize the input that came from op-amp for their counter of the circuit to make either high or low output signal that will came out to as a output signal then.