IT202B Special chip for modulation and demodulation
1、 Overview：
1. IT202B is a special chip for pulse modulation and demodulation. Eight pin dip package. The working power supply is 3-5v. It has the characteristics of high integration, low power consumption, static current of about 1mA and strong anti visible light interference ability. Only a few interface devices are needed.
2. It has internal shaping circuit and digital filtering function.
3. It has the characteristics of long detection distance.

2、 Logical state：
1.OP1 has high signal output; op2 has no high signal output.
2.OP1 has no signal output high; op2 has signal output high.
3.OP1 has high signal output; op2 has high signal output.
4.No signal output of OP1 is low; that of op2 is low.

3、 Typical circuit description：
1. R1 and R2 in the figure can be adjusted according to the detected object and distance.
2. Single beam photoelectric sensor st178 is our product. Other photoelectric sensors of our company can also be selected.
3. Only one input can be used. But input pull-down resistors R5 and R6 must be connected.
4. The smaller the resistance of R3 and R4 is, the better the anti-interference performance is. But the sensitivity will decrease. At this time, the resistance values of R1 and R2 can be adjusted to reach the detection distance used.