What is Capacitors and There Types

What is Capacitors

Capacitors are two-terminal elements used for filtering, energy storage, voltage spike suppression, and lots of alternative applications. In their simplest form, they consist of two parallel plates separated by an insulating material called a dielectric. Capacitors store electrical charge.

Capacitors Types

There are several different types of capacitors

Aluminium Electrolytic Capacitors

Ceramic Capacitors

Tantalum Capacitors

Film Capacitors

Polymer Capacitors

I. Aluminium Electrolytic Capacitors

Characteristic: aluminium Electrolytic Capacitors ar polarized, so that they can't be used with AC. They can achieve high capacitance value but with large variations, typically 20%.

Applications: These are useful in applications which do not need tight tolerances or AC polarization. They are most commonly used in power supplies for decoupling purposes, i.e. to reduce voltage ripple reaching the circuit. They are additionally used wide in DC/DC switch voltage converters.

II. Ceramic Capacitors

Characteristic: There are two main types of ceramic capacitors: Multi-layer chip capacitors (MLCCs) and ceramic disc capacitors. MLCCs are very widely used in electronic devices and are popular because they have high stability and low losses. They have lower Equivalent Series Resistance (ESR) and variation compared to electrolytic or tantalum capacitors however are able to do lower capacitance (only up to a couple of µF) . Because of high packing densities, MLCC capacitors provide a size advantage and are great for printed circuit boards (PCBs).

Applications: Since these are not polarized, they can be be used with AC. They are wide used as a ‘general-purpose’ electrical device and used for prime frequency interference, filtering, generator standardization and EMI suppression. Both MLCCs and ceramic disc capacitors ar more divided into 2 application classes:

Class I ceramic capacitors are accurate ( 5%) and temperature-compensated- they have very low change of capacitance with temperature. NP0/C0G ar standard, and have a tolerance of 30ppm/K, but are available only up to the nanoFarad (nF) range. Because they are very stable and accurate, they are used in frequency control applications such as resonant circuits for radio applications.

III. Tantalum Capacitors

Characteristic: These are a subtype of electrolytic capacitors and are highly polarized. Care needs to be taken as they are known to have catastrophic failure modes which can be triggered by voltage spikes even slightly more than rated voltage. They can achieve high capacitance value and are very stable over time. They are smaller in size than aluminum electrolytic capacitors of a similar capacitance however will handle lower most voltages.

Applications: because of their low leak current, stability, and high capacity, they are common for sample and hold circuits which rely on low leakage current to achieve long hold duration. They are additionally utilized in power offer filtering because of their smaller size and long term stability.

IV. Film Capacitors

Film capacitors ar non-polarized that makes them appropriate for AC signal use. They have low Equivalent Series Resistance (ESR) and coefficient of self induction (ESL) and ar utilized in A/D converters. They can handle high peak current and can thus be used as snubber capacitors to “snub” inductive kickback voltage spikes in DC-DC converters

V. Mica Capacitors

Mica capacitors ar non-polarized, have low losses, high stability, and have great high-frequency properties. They are useful for radio frequency circuits. Mica capacitors will price a couple of greenbacks per piece, so they are being replaced by ceramic capacitors for low-power applications. However, they continue to be important for prime power applications like RF transmitters because of their high breakdown voltage.

VI. Polymer Capacitors

Polymer capacitors are polarized similar to different electrolytic capacitors however have many benefits like lower losses because of lower ESR and longer time period. For typical aluminium electrolytic capacitors, there is a risk of electrolyte dry-out at lower temperatures, but due to the use of solid polymer material as dielectric, polymer capacitors have high reliability even at very low temperatures.

Polymer capacitors ar utilized in place of electrolytic capacitors for prime quality motherboards and DC-DC converters.