Optoizolator (also called transoptorem or optical isolator) is an electronic element that transfers electrical signals between two isolated circuits by using light. The value of the optical feedback in electronic circuits to ensure galvanic isolation was seen in the 60-ies. The XX century. Optoizolatory was founded then fotorezystorach and жеarówkach – the slowest, but most linear systems of this type. Still have a niche use in the audio industry and music. Commercialization of LED technology in the 70-ies. The XX century made it possible to develop more sophisticated optoizolatorów, which are now available in stores.
Optoizolator contains the light source. Almost always this indicator IR-radiationthat converts electrical input signal into light, the dielectric optical channel and a light detector to detect light emitter. It delivers electric energy directly, or modulates electric current flowing from an external power source. The sensor can be fotoopornik, photodiode, or fototranzystor fototriak. Since the LEDs can detect light, except for the conclusion it is possible to design a symmetric bi-directional optical isolators using them. As a rule, optoizolatory transmit digital signals (on-off), although some techniques allow use with analog signals.
Electronic equipment and transmission lines signal and power can be subjected to surges indukowanym to lightning, static electricity, etc. a lightning Strike can cause an increase in voltage up to 10,000 V. as high voltage spikes can damage the input circuit, as with all electronic devices. Optoizolatora main function is to block high voltages. This element eliminates the risk of transient processes in the signal chain. Commercially available optoizolatory can withstand input voltages up to 10 kV pulses with a rise time up to 25 kV/µs.
Choosing galvanic isolator, regardless of type, need to pay attention to two parameters. One of them is the maximum bitratethat will limit the speed of data transmission through the optical isolation barrier. The second parameter is the maximum allowable potential difference between the primary side and the secondary system. Most optoizolatorów available on the market, uses an inexpensive bipolar silicon sensors fototranzystorowe. They receive the average data transfer speed, sufficient for applications such as the isolation of signals in the automatic protection of digital interfaces. Quick optoizolatory use the PIN photodiodes in the mode fotoprzewodzenia.
Modern schemes transoptory to action, require a minimum number of external components. Elements of this type are adapted to their role of galvanic isolators digital lines, therefore the input and output of the system operates in standard TTL logic - 5 V, 3.3 V and other to taste. To implement typical optoizolatora diode and fototranzystorem, you only need two resistors. Available in our store transoptory multiple containing multiple isolators in a single housing, which facilitates installation and reduces the circuit BOARD area occupied galvanic isolation of signals.