I. What is Photocoupler?
Photocoupler is also known as optocoupler. To communicate electrical impulses, optocouplers employ light as a channel. It is frequently utilized in many circuits because it provides an excellent isolation effect on input and output electrical signals. It has evolved into one of the most diversified and adaptable optoelectronic devices available today. Light emission, light reception, and signal amplification are the three main components of an optical coupler. The input electrical signal causes the light-emitting diode(LED) to emit light of a specific wavelength, which is detected by the photodetector and converted into a photocurrent, which is then output after amplification. This completes the electrical-optical-electrical conversion, acting as input, output, and isolation at the same time. The optocoupler offers good electrical insulation and anti-interference characteristics since its input and output are isolated from each other and the electrical signal transmission is unidirectional.
Ⅱ. The classification of Photocoupler
Because there are so many different types and varieties of photoelectric couplers, the optoelectronics DATA handbook has over a thousand models, which can usually be categorized using the following methods:
(1) It can be classified as an external optical path photoelectric coupler (also known as a photoelectric interruption detector) or an interior optical path photoelectric coupler, depending on the optical path. The transmission type and reflection type photoelectric couplers are the two types of external optical path photoelectric couplers.
(2) It may be classified into two types based on the output form: a. Photosensitive device output type, which includes photodiode output type, phototransistor output type, photocell output type, and light thyristor output type, among others.
b. Type of NPN triode output, such as AC input, DC input, complementary output, and so on.
c.Darlington transistor output type, which includes both AC and DC inputs.
d. The type of logic gate circuit output, such as gate circuit output, Schmitt trigger output, tri-state gate circuit output, and so on.
e. Output type with low conduction (output low-level millivolts).
f. Type of optical switch output (on resistance less than ten).
g. Type of power output (IGBT/MOSFET, etc.)
(3) Coaxial type, dual in-line type, TO package type, flat package type, chip package type, and optical fiber transmission type are the different package types.
(4) Digital photocouplers (OC gate output type, totem pole output type, tri-state gate circuit output type, etc.) and linear photocouplers can be classified based on the transmission signal (can be divided into low drift type, high linearity Type, broadband type, single power supply type, dual power supply type, etc.).
(5) Photoelectric couplers can be classified as low-speed (phototransistor, photocell, etc. output type) or high-speed (phototransistor, photocell, etc. output type) (photodiode with signal processing circuit or photosensitive integrated circuit output type).
(6) It can be classified as a single channel, dual-channel, or multi-channel photocoupler based on the channel.
(7) It may be separated into regular isolation optocouplers (usually, optical glue potting is less than 5000V, and the empty seal is less than 2000V) and high-voltage isolation optocouplers based on isolation properties (can be divided into 10kV, 20kV, 30kV, etc.).
(8) It can be classified as a low power supply voltage type photoelectric coupler (usually 515V) or a high power supply voltage type photoelectric coupler based on the working voltage (generally greater than 30V).
