Electronic switch

Last updated

In electronics, an electronic switch is a switch controlled by an active electronic component or device. Without using moving parts, they are called solid state switches, which distinguishes them from mechanical switches. [1]

Contents

Electronic switches are considered binary devices because they dramatically change the conductivity of a path in electrical circuit between two extremes when switching between their two states of on and off.

History

Many people use metonymy to call a variety of devices that conceptually connect or disconnect signals and communication paths between electrical devices as "switches", analogous to the way mechanical switches connect and disconnect paths for electrons to flow between two conductors.

The traditional relay is an electromechanical switch that uses an electromagnet controlled by a current to operate a mechanical switching mechanism. Other operating principles are also used (for instance, solid-state relays invented in 1971 control power circuits with no moving parts, instead using a semiconductor device to perform switching—often a silicon-controlled rectifier or triac).

Early telephone systems used an electromagnetically operated Strowger switch to connect telephone callers; later telephone exchanges contain one or more electromechanical crossbar switches. Thus the term 'switched' is applied to telecommunications networks, and signifies a network that is circuit switched, providing dedicated circuits for communication between end nodes, such as the public switched telephone network.

The term switch has since spread to a variety of digital active devices such as transistors and logic gates whose function is to change their output state between logic states or connect different signal lines.

The common feature of all these usages is they refer to devices that control a binary state of either on or off, closed or open, connected or not connected, conducting or not conducting, low impedance or high impedance.

Types

The diode can be treated as switch that conducts significantly only when forward biased and is otherwise effectively disconnected (high impedance). Specific diode types that can change switching state quickly, such as the Schottky diode and the 1N4148, are called "switching diodes".

Vacuum tubes can be used in high voltage applications.

The transistor can be operated as a switch. The bipolar junction transistor (BJT) cutoff and saturation regions of operation can respectively be treated as a closed and open switch.

The most widely used electronic switch in digital circuits is the metal–oxide–semiconductor field-effect transistor (MOSFET). [2]

The analogue switch uses two MOSFET transistors in a transmission gate arrangement as a switch that works much like a relay, with some advantages and several limitations compared to an electromechanical relay.

The power transistor(s) in a switching voltage regulator, such as a power supply unit, are used like a switch to alternately let power flow and block power from flowing.

Hall switches are a type of Hall sensor that combine the analog Hall effect with threshold detection to produce a magnetically-operated switch.

The opto-isolator uses light from an LED controlled by a current which is received by a phototransistor to switch a galvanically-isolated circuit.

The insulated-gate bipolar transistor (IGBT) combines advantages of BJTs and power MOSFETs.

A silicon controlled rectifier (SCR) can be used for high speed switching for power control application.

A TRIAC (TRIode AC), equivalent to two back-to-back SCRs, is a bidirectional switching device.

A DIAC stands for DIode AC Switch.

A gate turn-off thyristor (GTO) is a bipolar switching device.

Electronic switches may also consist of complex configurations that are assisted by physical contact, for instance resistive or capacitive sensing touchscreens.

Network switches reconfigure connections between different ports of computers in a computer network.

Applications

Electronic switches are used in all kinds of common and industrial applications.

See also

Related Research Articles

<span class="mw-page-title-main">Amplifier</span> Electronic device/component that increases the strength of a signal

An amplifier, electronic amplifier or (informally) amp is an electronic device that can increase the magnitude of a signal. It is a two-port electronic circuit that uses electric power from a power supply to increase the amplitude of a signal applied to its input terminals, producing a proportionally greater amplitude signal at its output. The amount of amplification provided by an amplifier is measured by its gain: the ratio of output voltage, current, or power to input. An amplifier is defined as a circuit that has a power gain greater than one.

<span class="mw-page-title-main">Transistor</span> Solid-state electrically operated switch also used as an amplifier

A transistor is a semiconductor device used to amplify or switch electrical signals and power. It is one of the basic building blocks of modern electronics. It is composed of semiconductor material, usually with at least three terminals for connection to an electronic circuit. A voltage or current applied to one pair of the transistor's terminals controls the current through another pair of terminals. Because the controlled (output) power can be higher than the controlling (input) power, a transistor can amplify a signal. Some transistors are packaged individually, but many more in miniature form are found embedded in integrated circuits. Because transistors are the key active components in practically all modern electronics, many people consider them one of the 20th century's greatest inventions.

<span class="mw-page-title-main">Semiconductor device</span> Electronic component that exploits the electronic properties of semiconductor materials

A semiconductor device is an electronic component that relies on the electronic properties of a semiconductor material for its function. Its conductivity lies between conductors and insulators. Semiconductor devices have replaced vacuum tubes in most applications. They conduct electric current in the solid state, rather than as free electrons across a vacuum or as free electrons and ions through an ionized gas.

<span class="mw-page-title-main">Insulated-gate bipolar transistor</span> Type of solid state switch

An insulated-gate bipolar transistor (IGBT) is a three-terminal power semiconductor device primarily forming an electronic switch. It was developed to combine high efficiency with fast switching. It consists of four alternating layers (P–N–P–N) that are controlled by a metal–oxide–semiconductor (MOS) gate structure.

<span class="mw-page-title-main">Thyristor</span> Type of solid state switch

A thyristor is a solid-state semiconductor device with four layers of alternating P- and N-type materials used for high-power applications. It acts as a bistable switch. There are two designs, differing in what triggers the conducting state. In a three-lead thyristor, a small current on its gate lead controls the larger current of the anode-to-cathode path. In a two-lead thyristor, conduction begins when the potential difference between the anode and cathode themselves is sufficiently large. The thyristor continues conducting until the voltage across the device is reverse-biased or the voltage is removed, or through the control gate signal on newer types.

<span class="mw-page-title-main">Silicon controlled rectifier</span> Four-layer solid-state current-controlling device

A silicon controlled rectifier or semiconductor controlled rectifier is a four-layer solid-state current-controlling device. The name "silicon controlled rectifier" is General Electric's trade name for a type of thyristor. The principle of four-layer p–n–p–n switching was developed by Moll, Tanenbaum, Goldey, and Holonyak of Bell Laboratories in 1956. The practical demonstration of silicon controlled switching and detailed theoretical behavior of a device in agreement with the experimental results was presented by Dr Ian M. Mackintosh of Bell Laboratories in January 1958. The SCR was developed by a team of power engineers led by Gordon Hall and commercialized by Frank W. "Bill" Gutzwiller in 1957.

<span class="mw-page-title-main">TRIAC</span> Solid-state semiconductor device

A TRIAC is a three-terminal electronic component that conducts current in either direction when triggered. The term TRIAC is a genericised trademark.

A power semiconductor device is a semiconductor device used as a switch or rectifier in power electronics. Such a device is also called a power device or, when used in an integrated circuit, a power IC.

<span class="mw-page-title-main">Power electronics</span> Technology of power electronics

Power electronics is the application of electronics to the control and conversion of electric power.

A snubber is a device used to suppress a phenomenon such as voltage transients in electrical systems, pressure transients in fluid systems or excess force or rapid movement in mechanical systems.

<span class="mw-page-title-main">Electronic component</span> Discrete device in an electronic system

An electronic component is any basic discrete electronic device or physical entity part of an electronic system used to affect electrons or their associated fields. Electronic components are mostly industrial products, available in a singular form and are not to be confused with electrical elements, which are conceptual abstractions representing idealized electronic components and elements. A datasheet for an electronic component is a technical document that provides detailed information about the component's specifications, characteristics, and performance.

<span class="mw-page-title-main">Power MOSFET</span> MOSFET that can handle significant power levels

A power MOSFET is a specific type of metal–oxide–semiconductor field-effect transistor (MOSFET) designed to handle significant power levels. Compared to the other power semiconductor devices, such as an insulated-gate bipolar transistor (IGBT) or a thyristor, its main advantages are high switching speed and good efficiency at low voltages. It shares with the IGBT an isolated gate that makes it easy to drive. They can be subject to low gain, sometimes to a degree that the gate voltage needs to be higher than the voltage under control.

<span class="mw-page-title-main">Electronic symbol</span> Pictogram used to represent various electrical and electronic devices or functions

An electronic symbol is a pictogram used to represent various electrical and electronic devices or functions, such as wires, batteries, resistors, and transistors, in a schematic diagram of an electrical or electronic circuit. These symbols are largely standardized internationally today, but may vary from country to country, or engineering discipline, based on traditional conventions.

An H-bridge is an electronic circuit that switches the polarity of a voltage applied to a load. These circuits are often used in robotics and other applications to allow DC motors to run forwards or backwards. The name is derived from its common schematic diagram representation, with four switching elements configured as the branches of a letter "H" and the load connected as the cross-bar.

<span class="mw-page-title-main">Solid-state relay</span> High-power solid-state electronic switching device responding to an external control signal

A solid state relay (SSR) is an electronic switching device that switches on or off when an external voltage is applied across its control terminals. They serve the same function as an electromechanical relay, but solid-state electronics contain no moving parts and have a longer operational lifetime. Solid state relays were invented in 1971 by the Crydom Controls division of International Rectifiers. After a number of corporate acquisitions, Crydom is now part of Sensata.

<span class="mw-page-title-main">CircuitLogix</span> Electronic circuit simulator software

CircuitLogix is a software electronic circuit simulator which uses PSpice to simulate thousands of electronic devices, models, and circuits. CircuitLogix supports analog, digital, and mixed-signal circuits, and its SPICE simulation gives accurate real-world results. The graphic user interface allows students to quickly and easily draw, modify and combine analog and digital circuit diagrams. CircuitLogix was first launched in 2005, and its popularity has grown quickly since that time. In 2012, it reached the milestone of 250,000 licensed users, and became the first electronics simulation product to have a global installed base of a quarter-million customers in over 100 countries.

<span class="mw-page-title-main">Active rectification</span>

Active rectification, or synchronous rectification, is a technique for improving the efficiency of rectification by replacing diodes with actively controlled switches, usually power MOSFETs or power bipolar junction transistors (BJT). Whereas normal semiconductor diodes have a roughly fixed voltage drop of around 0.5 to 1 volts, active rectifiers behave as resistances, and can have arbitrarily low voltage drop.

The following outline is provided as an overview of and topical guide to electronics:

<span class="mw-page-title-main">Field-effect transistor</span> Type of transistor

The field-effect transistor (FET) is a type of transistor that uses an electric field to control the flow of current in a semiconductor. It comes in two types: junction FET (JFET) and metal-oxide-semiconductor FET (MOSFET). FETs have three terminals: source, gate, and drain. FETs control the flow of current by the application of a voltage to the gate, which in turn alters the conductivity between the drain and source.

References

  1. Teja, Ravi (2021-05-03). "What is a Switch? What are the Different Types of Switches?". ElectronicsHub. Archived from the original on 2023-01-23. Retrieved 2023-06-27.
  2. Bapat, Y. N. (1992). Electronic Circuits and Systems : Analog and Digital,1e. Tata McGraw-Hill Education. p. 119. ISBN   978-0-07-460040-5.