An optoisolator (also called an optical insulator) is an electronic component and conductor that consists of one or more photoemitors. An optoiser transmits electrical signals between two isolated electrical circuits using light. The value of optical coupling in electronic circuits to ensure galvanic isolation was noticed as early as the 1960s. Back then, optoisolators were still based on photoresistors and light bulbs - the slowest, but also the most linear systems of this type. Such solutions still have their niche applications - for example in the audio and music industry. However, the mass commercialization of LED technology in the 1970s made it possible to develop more modern types of optoisolators, which are still available in stores today.
Nowadays, optoisolators are commonly used for galvanic separation of circuits in control and automation systems, as well as for work in measurement techniques. If you are creating a DIY electronic project that falls under the above categories, you will probably need a good optoisolator. Check out all the products below and choose the one that suits your individual project best!
How to choose an optoisolator? As when choosing any type of electronic component, attention should be paid to detailed technical parameters. When choosing a galvanic isolator, regardless of the type, first of all, two parameters should be analyzed. The first is the maximum allowable baud rate. This parameter indicates to what extent the device will limit the communication speed through the optical isolation barrier. The second parameter, on the other hand, is the maximum permissible potential difference between the primary and secondary side of the system.
Most of the optoisolators available on the market use inexpensive, bipolar silicon phototransistor sensors. They achieve an average data transfer rate that is sufficient for applications such as signal isolation in automation or protection of digital interfaces. It is worth knowing that the fastest optoisolators use PIN photodiodes in the photoconductive mode.
A characteristic feature of the optoisolator is that it contains a light source. It is almost always an IR LED that converts the electrical input signal into light, a dielectric optical channel, and a light detector that detects the emitter light. The device therefore generates electricity directly or modulates the electricity flowing from an external power source. This sensor may be a photoresistor, photodiode, photo transistor or phototriac. Since LEDs can detect light in addition to emitting it, it is possible to construct symmetrical bi-directional optical insulators using them. Typically, optoisolators transmit digital signals (on-off), although some techniques allow them to be used with analog signals.
In connection with the above, there are many advantages of using galvanic isolation in electronic systems. Electronic equipment, signal and power transmission lines can be subjected to voltage spikes induced by lightning, electrostatic and other discharges. Sudden spikes and spikes in voltage can permanently damage input circuits and entire electronic devices. However, if we use an optoisolator, it is possible to block such high voltages and their negative consequences for the entire electronic project.
Modern integrated optocouplers only require a minimal amount of external components to operate. These devices function as galvanic isolators of digital lines. As a result, the input and output of the system work in the TTL logic standard - 5 V, 3.3 V and others.
Despite the fact that optoisolators are not essential devices for every project, on the other hand, the use of optoisolators for various integrated circuits is very simple. Only two resistors are needed to implement a typical optoisolator with an LED diode and a phototransistor. In this category you will find multiple optocouplers containing several insulators in one housing, they facilitate assembly and reduce the surface area on the PCB taken up by galvanic isolation of signals. Be sure to check all products and contact us if necessary!