Optocoupler works

Couplers use light as the medium for transmitting electrical signals. It has a good isolation effect on the input and output electrical signals, so it is widely used in various circuits. At present, it has become one of the most versatile and versatile optoelectronic devices. Optocouplers generally consist of three parts: light emission, light reception, and signal amplification. The input electrical signal drives a light emitting diode (LED) to emit a certain wavelength of light, which is received by the photodetector to generate a photocurrent, which is further amplified and output. This completes the electro-optical-electrical conversion, which functions as input, output, and isolation. Because the optocoupler input and output are isolated from each other and the electrical signal transmission is unidirectional, it has good electrical insulation and anti-jamming capability. Therefore, it can greatly improve the signal-to-noise ratio as a terminal isolation element in long-term transmission information. In the computer digital communication and real-time control as a signal isolation interface device, can greatly improve the reliability of computer work.

Since the input of the optocoupler is a low-resistance element that operates in the current mode, it has a strong common-mode rejection capability.