Classification and use of ceramic capacitors

Author: Release time:2019-10-28 Source: Font: Big Middle Small View count:580

Ceramic capacitors are divided into high-frequency ceramics and low-frequency ceramics. A capacitor with a small positive temperature coefficient of capacitance for use in a highly stable tank circuit as a loop capacitor and a pad capacitor.

Low-frequency ceramic capacitors are limited to bypass or DC-blocking in circuits with lower operating frequencies, or where stability and loss are not critical (including high frequencies). Such capacitors are not suitable for use in pulse circuits because they are susceptible to breakdown by pulse voltages. Ceramic capacitors can be divided into plug-in and chip-type according to different packages! According to different media, they can be divided into Class I ceramic capacitors and Class II ceramic capacitors. Usually NP0, SL0, COG are Class I ceramic capacitors, X7R, X5R, Y5U Y5V is a class II ceramic dielectric capacitor. Class I ceramic dielectric capacitors have good capacity stability and basically do not change with temperature, voltage, time, etc., but the general capacity is very small, and the capacity stability of class II ceramic dielectric capacitors is very poor. As the temperature, voltage, and time vary greatly, ceramic capacitors are generally used in applications where capacity stability is not critical, such as filtering!

capacitors

High-voltage ceramic capacitors used in high-power and high-voltage fields are required to have small size, high withstand voltage and good frequency characteristics. In recent years, with the advancement of materials, electrodes and manufacturing technology, the development of high-voltage ceramic capacitors has made great progress and has been widely used. High-voltage ceramic capacitors have become an indispensable component of high-power high-voltage electronic products. The use of high-voltage ceramic capacitors is mainly divided into power equipment for power transmission and distribution systems and equipment for processing pulse energy.

Classification and use of ceramic capacitors

1. Ceramic capacitors are classified by voltage

Press voltage: ultra high pressure, high pressure, low voltage, AC

Ultra high pressure: ≥10KVdc;

High pressure: ≥500Vdc, <10KVdc;

Low pressure: ≥16Vdc, <500KVdc;

Exchange: Specifically refers to 250Vac and 400Vac. That is, the Y capacitor.

2. Ceramic capacitors are classified according to temperature characteristics

According to the temperature characteristics can be divided into three categories:

Class 1: high frequency ceramic capacitors, NP0, SL, etc.;

Class 2: High dielectric constant capacitors, such as Y5P, Y5U, Y5V, etc.

Category 3: Semiconductor type ceramic capacitors, in principle, Y5P, Y5U, Y5V. In fact, the current Y5V is the main.

3. What is the temperature characteristic?

It refers to the rate of change of the capacitance of the capacitor relative to the capacitor at a normal temperature range within a specified temperature range.

For example, NP0, in the temperature range of -25°C to +85°C, the allowable change in capacitance is less than 60ppm for every 1°C change in temperature with respect to 25 °C.

capacitors

For example, Y5P, in the temperature range of -25 ° C to +85 ° C, allows a rate of change of ± 10% with respect to the capacity change at 25 ° C.

Code: Y: -25 °C; 5: +85 °C

Rate of change: P: ±10%;

U: +22%, -56%;

V: +22%, -82%.

Ceramic capacitor use

Class 1: The temperature coefficient is small, suitable for tuning circuits and circuits that require compensation effects.

Class 2: High dielectric constant, suitable for bypass, coupling, DC blocking and filtering circuits.

Category 3: large capacity, small size, low voltage. Used for filtering, bypassing, and coupling circuits.

Communication: Anti-electromagnetic interference.

In general, in a DC circuit, the capacitor is equivalent to an open circuit. The function of blocking DC is to prevent DC from passing through and let the AC pass.

Ceramic capacitors have the following specific uses. 1. Bypass (decoupling) This is a low impedance path for some parallel components in an AC circuit.

In electronic circuits, both decoupling capacitors and bypass capacitors act as anti-interference. The capacitors are located at different positions and the calling is different.

For the same circuit, the bypass capacitor uses the high-frequency noise in the input signal as the filtering object to filter the high-frequency noise carried by the pre-stage, and the decoupling capacitor is also called decoupling. Capacitance is to filter the interference of the output signal

We can often see that a decoupling capacitor is connected between the power supply and the ground. It has three functions: one is the storage capacitor of the integrated circuit; the other is to filter out the high frequency noise generated by the device and cut it off. The path through which the power supply loop propagates; the third is to prevent the noise carried by the power supply from interfering with the circuit

The ceramic capacitor used in the coupling circuit is called a coupling capacitor. In a resistor-capacitor-coupled amplifier and other capacitive coupling circuits, this capacitor circuit is used in large quantities. It acts as a DC-connected AC. It acts as a connection between the two circuits, allowing The AC signal passes through and is transmitted to the next stage circuit

The ceramic capacitor used in the filter circuit is called a filter capacitor. The filter capacitor removes the signal in a certain frequency band from the total signal. Therefore, in the power circuit, the rectifier circuit converts the alternating current into a pulsating DC, and in the rectification. After the circuit is connected to a larger capacity ceramic capacitor, using its charge and discharge characteristics, the rectified pulsating DC voltage becomes a relatively stable DC voltage.

Resonant capacitors used in LC resonant circuits are called resonant capacitors. These capacitor circuits are required in both LC parallel and series resonant circuits.

Temperature compensation compensates for the effects of insufficient temperature adaptation of other components to improve circuit stability

Tuning is the system tuning of frequency-dependent circuits, such as cell phones, radios, televisions

Energy storage means storing energy and releasing it when necessary

Such as camera flash, heating equipment, etc.

(Currently, the energy storage level of many capacitors can be close to the level of lithium batteries, and the energy stored in one capacitor can be used for one mobile phone for one day)

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