Discrete components – characteristics and examples
Discrete components – characteristics and examplesDate of publication: 30-12-2022 🕒 6 min read
Electronic components can be classified in many ways and assigned to various categories, but there are three main divisions that are universally accepted. Components can be passive or active, that is only drawing electrical energy or impacting the signals actively. Components can also be classified due to the way in which they are mounted. These are classic THT constructions, mounted with the use of through-hole technology or SMD designs for surface-mount technology. Components can also be classified due to the scale of integration, and here discrete and integrated components are differentiated.
What are discrete components
A discrete component can be defined as a single part of an electrical circuit with one dominant function. It can be for example a resistor, a capacitor or a diode. Discrete electronic components can be passive or active. They are also different in the way in which they are mounted – they are designed as THT components or small SMD components.
The division into discrete and integrated components is mostly intended to separate singular components from integrated and hybrid circuits, inside which many different functions are usually performed. Due to the growing miniaturisation, there are fewer and fewer discrete components – it is easier for manufacturers to include a few additional resistors inside a singular silicon core than to manufacture them as separate components. It needs to be remembered, however, that singular components will never disappear, because they must be manufactured in this exact form due to the way many devices are designed and built.
Examples of discrete components – types
Resistors
Resistors are one of the most common types of discrete components. Their purpose is to limit the flowing current and turn its surplus into heat. Resistors are linear components, which means that the occurring voltage drop is directly proportional to the flowing current. Resistors differentiate in shape, which depends on the usage, but the most common ones are cylinder-shaped carbon resistors, with colourful stripes on the casing to determine the resistance value of a given component. In modern SMD structures, carbon has been replaced with special metals, such as: nickel, tin and chrome.
Capacitors
Capacitors are just as commonly used as resistors. They are passive discrete components, designed to store energy. In order to make that possible, capacitors are made of two transformers (plates) separated by dielectric, and inside the magnetic field of those transformers energy is stored. There are numerous applications of these electronic components, from classic filtration in power supply systems, to storing energy in discharge lamp circuits. Capacitors are manufactured with many different kinds of housings, but usually these are THT cylinders or tiny cuboids adapted to SMD mounting.
Capacitors available in the TME catalogue
Coils
Coil is an electronic component whose operation is based on electromagnetic induction. It has a shape of a winding on a ferromagnetic core, usually cylinder-shaped, but coils without a core also exist. These components are called solenoids. In direct current circuits, coils are purely resistive, and their character changes in the case of alternating current. In that case, they are characterised by reactance, which is a parameter related to capacitance and induction.
Inductors
Inductors, similarly to coils, are electronic components used for preventing sudden changes in electric current or for limiting its value without power loss (in alternating current circuits). Similarly to coils, inductors are manufactured as windings on a magnetic core. There are quite a lot applications in the case of inductors, so here we list only a few basic ones: they serve as anti-interference elements in LC filters, energy storages in power supply systems, they are applied in power systems of fluorescent lamps and in discharge lamps as ballasts.
Inductors available in the TME catalogue
Schottky and rectifier diodes
Rectifier diodes are one of the classic examples of discrete semiconductor components. Their main purpose is the rectification of alternating current, so they are common in all kinds of AC adapters. These semiconductor components are made mostly of silicon and a few other elements. Semiconductor diodes have two leads – anode and cathode, placed on the opposite sides of a small cylinder, although diodes in other shapes also exist and are designed mostly for SMD mounting.
Schottky diodes available in the TME catalogue
Bipolar junction transistors
Bipolar junction transistors are another example of discrete semiconductor components. The silicon-based ones are the backbone of the modern world of electronics. Thanks to transistors, it is possible to construct easily a sort of a key activated by electrical energy. Besides, this element may amplify signals, which is particularly useful in analogue designs. Transistors are housed in many kinds of casings, from classic TO92, to much greater power structures placed inside TO3. Moreover, there are many casings designed for surface mounting.
PIN diodes
One of the most interesting types of discrete components is a PIN diode. On the outside, it looks like a classic semiconductor diode, yet they differ in terms of their internal structure. Inside a PIN diode, between the layers of P and N semiconductors, there is a poorly doped, intrinsic semiconductive region. Thanks to such s solution, PIN diodes have poor rectifying qualities, but work very well with high-frequency signals. They are used in all kinds of frequency attenuators, radiation detectors or high-voltage power systems.
PIN diodes available in the TME catalogue
Bridge rectifiers
Bridge rectifiers (Graetz bridges), although they are designed as singular integrated circuit chips, are also discrete components. These constructions are full-range rectifiers, designed to convert alternating current. Bridges are supported by four semiconductor diodes connected in an appropriate way and can be encountered in AC adapters. These circuits are housed in different kinds of casings, from small DIP4, to much bigger GBI, often accompanied by heat sinks that dissipate excess heat.
Bridge rectifiers available at TME
IGBTs
IGBTs, also known as insulated gate transistors, combine the advantages of two transistor types: the easy adjustment of unipolar transistors with the breakdown voltage and speed of bipolar constructions. Thanks to these properties, these components are successfully applied in inverters, as connectors enabling the blocking of high kV voltages and switching on high currents above 1 kA.
TVS diodes
TVS diodes, the so-called transil diodes may be impossible to distinguish from other semiconductor diodes at the first glance, but their application is completely different. These components are mostly used as protection for other electronic components from the destructive effect of overvoltage. Such structures operate similarly to a varistor, but are much faster – their reaction time is given in picoseconds. After exceeding the threshold voltage, the diode’s resistance decreases sharply, which allows the circuit to be broken quickly enough to save other elements.
TVS diodes available in the TME catalogue
Vacuum tube
Classic vacuum tubes are also discrete components. It is worth remembering, even though such designs are a rarity nowadays. Before a transistor was invented, these very components were the core of the majority of control systems. Vacuum tubes were designed as glass bulbs, inside which, depending on the type, from two to even eight electrodes were placed. Those were the anode and the cathode with many grids.
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