Functions and characteristics of photocouplers

Due to the wide variety of optocouplers, unique structures and outstanding advantages, they are widely used, mainly in the following occasions:
(1) Application in logic circuits
Optocouplers can form various logic circuits. Since the anti-interference and isolation performance of optocouplers are better than those of transistors, the logic circuits formed by them are more reliable.
(2) Application as solid-state switch
In switch circuits, it is often required that there is good electrical isolation between the control circuit and the switch. This is difficult to achieve for general electronic switches, but it is easy to achieve with optocouplers.
(3) Application in trigger circuits
Optocouplers are used in bistable output circuits. Since the light-emitting diodes can be connected in series to the emitter loops of the two tubes, the problem of output and load isolation can be effectively solved.
(4) Application in pulse amplifier circuits
Optocouplers are used in digital circuits to amplify pulse signals.
(5) Application in linear circuits
Linear optocouplers are used in linear circuits and have high linearity and excellent electrical isolation performance.
(6) Applications in special occasions
Photocouplers can also be used in high-voltage control, replacing transformers, replacing contact relays, and in A/D circuits.

Optocoupler Introduction:

Optocoupler is a device that packages infrared light emitting device, infrared light receiving device and signal processing circuit in the same socket. When the input electrical signal is added to the input light emitting device LED, the LED emits light, the light receiving device receives the light signal and converts it into an electrical signal, and then directly outputs the electrical signal, or amplifies the electrical signal and processes it into a standard digital level output, thus realizing the "electric-optical-electrical" conversion and transmission. Light is the medium of transmission, so the input and output ends are electrically insulated, also known as electrical isolation.

Photocoupler Features
Due to its unique structural characteristics, the photocoupler has the following obvious advantages in actual use:
(1) It can effectively suppress the noise of the ground loop, eliminate ground interference, and completely isolate the signal field from the main control end electrically, avoiding accidental damage to the main control system. (2) It can
transmit electrical signals between different potentials and different impedances, and has functions such as amplification and shaping of the signal, which greatly simplifies the actual circuit design. (3
) Fast switching speed. The response speed of high-speed photocouplers reaches the order of ns, which greatly expands the application of photocouplers in digital signal processing.
(4) Small size, most devices use dual-in-line packaging, with a variety of structures such as single channel, dual channel and up to eight channels, which is very convenient to use.
(5) It can replace transformer isolation, will not generate spike noise due to contact bounce, and has strong vibration and impact resistance.
(6) In addition to power supply monitoring, high-linearity photocouplers are also used in medical equipment, which can effectively protect the life safety of patients.