Tel: +86-755-27823321


You are here: Home > Company > Content
Strong Interference Resistance Of Optocoupler
- Sep 08, 2017 -

Optical coupler (Opticalcoupler, English abbreviation for OC) also known as opto-electronic isolator or optocoupler, referred to as Optocoupler. It is a device that transmits electrical signals using light as a medium, and usually encapsulates a light-emitting diode (IR LED) and a light emitting device (photosensitive semiconductor tube) within the same shell. When the input signal is added, the light is emitted by the light device, and the optical current is generated from the output end, thus the "electric-optical-electric" conversion is realized. Optocoupler The photoelectric coupler with input signal is coupled to the output end by light, because it has the advantages of small size, long life, no contact point, strong anti-interference ability, insulation between output and input, one-way transmission signal and so on, it has been widely used in digital circuit.

Optocoupler is the transmission of signals in the form of light, the internal circuit is a photosensitive transistor and light-emitting diode combined into an electronic component is encapsulated in a plastic shell, access to the circuit, the input signal through the light-emitting diode into the same regular beam, Optocoupler and then to the photosensitive transistor. The photosensitive transistor converts the received beam to the same beam signal as the light-emitting diode, which realizes the conversion of the electric-optical-electric. Optocoupler Light plays the role of the media.

Optocoupler is a semiconductor optoelectronic device that encapsulates a light-emitting element and a photosensitive element in the same shell and transmits electrical signals in the middle by the conversion of electricity → light → electricity. The optocoupler for transmitting analog signal is diode and light receiver is photosensitive transistor. When there is an electric current through the light-emitting diode, it forms a light source, the light source exposure to the photosensitive transistor surface, so that the photosensitive transistor to produce a collector current, Optocoupler the size of the current and the intensity of the light, that is, the size of the diode through the positive current is proportional. Because the optical coupling between the input end and the output end is transmitted through the optical signal, the two parts are completely isolated from each other, and there is no feedback and interference from the electrical signal, so the performance is stable and the anti-interference ability is strong. The coupling capacitance between the light-emitting tube and the photosensitive tube is small (around 2PF) and the pressure is high (2.5KV), Optocoupler so the common-mode inhibition ratio is very high. The electrical isolation between the input and output depends on the insulation resistance between the two parts of the power supply. In addition, because of its small input resistance (about 10 ω), the noise of the high internal resistance source is equivalent to the short connection. Therefore, the analog signal isolation circuit composed of optocoupler has excellent electrical properties.

The relationship between the transfer characteristics and the temperature of the optocoupler can be seen, if the analog isolation circuit composed of the optical coupling is stable and practical, Optocoupler the effect of the dark current (ICBO) should be eliminated to improve the linearity, so that the static working point IFQ automatically adjusts with the change of temperature, so that the output signal remains symmetrical, The dynamic range of the input signal is changed automatically with the change of temperature, in order to counteract the effect of β value on the temperature change, and to ensure the stability of the circuit working state.

Optocoupler takes the optical signal as the medium to realize the coupling and transmission of the electrical signal, and the input and output are completely isolated on the electric circuit, Optocoupler which has the characteristics of strong anti-interference ability. For the industrial application measurement and control system which includes both the weak control part and the strong electric control part, the optical coupling isolation can be used to realize the isolation of weak and strong electricity, and to achieve anti-jamming.