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Chip Monolithic Ceramic capacitor with the circuit design

In Electronic Infomation Category: C | on April 22,2011

Chip Monolithic Ceramic Capacitors

have been born nearly 50 years. Meanwhile, Chip Monolithic Ceramic capacitor dielectric body through the thin layer of dielectric material, and TEA7089A datasheet and new development, the steady implementation of small and TEA7089A price and large. As a result, chip monolithic ceramic capacitor spread gradually from the first aluminum electrolytic capacitors, tantalum electrolytic capacitors, film capacitors to capture the market, expanding its sphere of influence (Figure 1). Such as the capacitance in the range of products 10 ~ 100F, 2002 Chip monolithic ceramic capacitors proportion is almost zero, but with small and TEA7089A suppliers and large capacity to develop in the direction, by 2005 to market products can be , Chip Monolithic Ceramic capacitor proportion to rise to about 1 / 3 to 2007 is increased to about 2 / 3 (Figure 2).

Figure 1: The ever-expanding range of monolithic ceramic chip capacitors with rated voltage of the vertical axis, the electrostatic capacity of the horizontal axis

Figure 2: the proportion of high-capacity products, according to the different capacitance of the capacitors total demand for a statistical,

were clear monolithic ceramic chip capacitors, electrolytic capacitors, tantalum electrolytic capacitors each share.

can be seen from the figure, monolithic ceramic chip capacitors in high-capacity products, the proportion increased every year.

This graph shows the range of products of various capacitors. Chip Monolithic Ceramic capacitor rapidly advancing direction of the large capacity, gradually expanding its scope. The electrolytic capacitors and tantalum electrolytic capacitors is also working to high pressure and large capacity in the direction of development in order to catch up with Chip monolithic ceramic capacitors.

Chip Monolithic Ceramic capacitor and aluminum electrolytic capacitors and tantalum electrolytic capacitors in the market boundary products, rated voltage of 10V or so capacity 100F, V, compared with tens of dozens of F. In the future, this line will undoubtedly further toward the direction of moving large electrostatic capacity.

ESR low voltage tolerance of abnormal strong

Chip monolithic ceramic capacitor on the expansion of its sphere of influence played a role in promoting the small and large capacity. However, select capacitors for electronic equipment, consider the characteristics of not only dimensions and electrostatic capacity. Chip Monolithic Ceramic Capacitors by no means a panacea. Has strengths in the (merits), but also there are also weaknesses (weaknesses), so the need for chip monolithic ceramic capacitors of various characteristics of attention.

Here Table 1 shows the sheet through the monolithic ceramic capacitor, electrolytic capacitors, tantalum capacitors are compared the results. Chip Monolithic Ceramic capacitor has two advantages.

Table 1 Comparison of various capacitors

One is the equivalent series resistance (ESR: Equivalent Series Resistance) and, thus, excellent frequency characteristics. ESR is the impedance of the capacitor internal electrodes. If the impedance of the larger, in addition to the noise absorption characteristics to determine the basis of merits, which will deteriorate the frequency characteristics of impedance, the impedance caused by heat can not be ignored. Therefore, installed in the microprocessor, DSP and the MCU and other semiconductor chips around, used to absorb noise decoupling purposes, the lower ESR value is an essential element.

Other is the abnormal voltage has a strong tolerance. For example, the rated voltage of 16V, 10F capacitance of products for the DC breakdown voltage when compared to aluminum electrolytic capacitors is only 30V, tantalum electrolytic capacitors, but also 30 ~ 60V. Chip Monolithic Ceramic capacitor while high, can reach about 200V. Therefore, even if electronic equipment there for some reason the surge voltage or pulse voltage, if you have a chip monolithic ceramic capacitors, then, can still cause a failure of the possibility of insulation breakdown in the lower level of the control.

Need to pay attention to the temperature characteristics and the DC voltage characteristics

The other hand, monolithic ceramic chip capacitors generally have two shortcomings. The first is the poor temperature characteristics

. Concrete manifestation of the electrostatic capacity of the large magnitude of temperature change. Changes in the capacity of electrolytic capacitors -55 ~ +125 temperature range is 15%, while the chip monolithic ceramic capacitor is different from some species (such as characteristics of the product F) +30 ~ -80% of the will significantly change the range. Therefore, the chip monolithic ceramic capacitors used in cars and other high temperature environment inside the vehicle or ski cold environment such as electronic equipment, taking into account the need to change the basis of capacity up design electronic circuits.

However, we must note that the disadvantage of poor temperature characteristics exist only in the use of dielectric material barium titanate (BaTiO3) of high dielectric constant type (Class 2, CLASS-II) Chip Monolithic Ceramic Capacitors in. Use of titanium dioxide (TiO2) 1 class (CLASS-I) Chip Monolithic Ceramic capacitor, in the range of -55 ~ +125 temperature coefficient of the maximum capacity of only 60ppm / . Dioxide dielectric constant but minor problems exist, it is not possible to achieve high-capacity products.

The second characteristic is the existence of DC voltage (DC bias characteristics). DC voltage characteristic is defined as monolithic ceramic chip capacitors to the DC voltage is applied after the actual capacitance will decrease (Fig. 3). For example, in the rated voltage of 6.3V, the chip capacitance is 100F implementation of monolithic ceramic capacitor voltage plus the DC 4V, B characteristics of the product if it is, then the capacitance will be reduced by about 20%, F characteristics of products will be reduced even about 80%. The electrolytic capacitors and tantalum electrolytic capacitors are not of this phenomenon.

Figure 3: DC voltage characteristics of chip monolithic ceramic capacitor with DC voltage applied to reduce the characteristics of the actual capacitance. This is also known as the DC bias characteristics

Therefore, the choice of chip monolithic ceramic capacitor, requires prior determination of the DC voltage component signals, control the actual degree of capacitance reduction (see "DC bias factors to consider markers, JEITA implementation of standardized"). However, "using the most advanced micro-machining technology to produce semiconductor chips, the supply voltage has been reduced to very low levels. Recently, the work voltage of about 1.0V the chip is not unusual. Therefore, the current voltage characteristics of the problem is not significant "(Murata Manufacturing Business Division of the Minister of components within the public and the mountain.)

In addition, the DC voltage characteristics of the problem occurs is limited to 2 products. The reason is strong barium titanate dielectric bodys sake. Therefore, using their own body for the smooth power of a titanium dioxide products DC-voltage characteristics of the problem does not occur.

DC bias factors to consider markers, JEITA implementation of standardized

Chip Monolithic Ceramic capacitor with capacitance easily be applied DC voltage. The so-called DC bias characteristics. Therefore, for electronic circuits in real time, get the capacity and specifications are not the same as the value on the things that happen from time to time. If the designers of electronic equipment do not have the DC bias characteristics of the case, worst case is designed electronic equipment and even may not work correctly.

To this end, Japan Electronics and Information Technology Industries Association (JEITA) established in 2007, "JEITA RCX-2326" Standard specifications and requirements identified in the performance of a sexual state of the applied DC voltage determined by the capacity of the value. The standard provisions of the object chip monolithic ceramic capacitor is the use of barium titanate dielectric material of the two products. And the limit is rated at 2.5V products. That is, the standard is based on microprocessors, DSP and the MCU and other power supply line decoupling applications used for the object.

Applied voltage were measured 1.25V DC

Relatively new standard and the original standard "JIS C 5101-22", differences are summarized as follows (Table A).

Table A DC-voltage characteristics for the existing specifications with new specifications compare

In the determination of capacitance, the new specifications to the applied DC voltage and 0.1Vrms 1.25V AC voltage state on the capacity were determined. The original "JIS C 5101-22" specification does not require the applied DC voltage, but requires the applied voltage of 0.5 ~ 1Vrms exchange capacity was determined under the state.

In addition, the electrostatic capacity to allow the determination of bias and temperature characteristics are also 1.25V DC voltage applied to the state were determined. The original specification is not required to apply the DC voltage.

Development of this new specification will undoubtedly enable the designers of electronic devices to more easily choose the best for their monolithic ceramic chip capacitors. Currently, Murata has been put in the market of products to meet the new specifications.

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