#OPTO ISOLATOR HOW TO#
#OPTO ISOLATOR DRIVER#

Of course, the electrical integration must be done according to the type and specifications of the particular isolator used.

#OPTO ISOLATOR DRIVER#

Similarly, some devices contain a driver circuit which receives an input voltage signal.Ī special form is the solid-state relay, which is explicitly used for switching a load, somewhat similar to a conventional relay based on a magnetically actuated mechanical switch the receiver may contain one or two MOSFETs (a special kind of transistors). Others contain a complete receiver circuit, which requires some constant operation voltage and supplies an output voltage signal. Simple isolators contain only the LED and a phototransistor, for example (see Figure 1), and no additional electronics. There are opto-isolators with integrated driver circuits for transmitter and receiver. There are even devices containing a triac the output then remains switched on even when the input signal disappears, until the output current is interrupted in other ways. There are also isolators with other kinds of receivers, for example photoresistors (which are largely outdated) or p–i–n photodiodes, or with Darlington phototransistors for a particularly high current transfer your ratio (see below).Įarly devices used an incandescent lamp as transmitter. Those are mounted in a distance of a few millimeters, for example, within an opaque package. Typically, one uses an infrared light-emitting diode (LED, usually GaAs-based) and a silicon phototransistor. Of course, one chooses an emitter which well matches the spectral response of the receiver. The operation principle of an opto-isolator is to convert an electrical signal to an optical signal, transmit that light signal and to convert it back into an electrical signal. Similar functions are often obtained with transformers, which however cannot transmit DC signals and are typically substantially larger and more heavy than opto-isolators.Įven though the term optical isolators is sometimes used, such devices must not be confused with optical isolators like Faraday isolators, which allow light transmission in one direction only. of dual in-line type, as otherwise also used for small electronic components such as operational amplifiers. Opto-isolators, also called optocouplers or photocouplers, are optoelectronic components which can be used to transmit analog or digital electrical signals between two electrical circuits while providing electrical isolation.Īn opto-isolator is normally provided in a compact package, e.g.

#OPTO ISOLATOR HOW TO#

How to cite the article suggest additional literatureĪ common opto-isolator contains an LED and a bipolar phototransistor. Encyclopedia > letter O > opto-isolators Opto-isolatorsĭefinition: optoelectronic devices for signal transmission with electrical isolation between two electrical circuitsĪlternative terms: optocouplers, photocouplers, optical isolators

Opto isolator