New material ceramic capacitors and applications on LED bulbs

Chip ceramic capacitor

6035 18.432 ceramic

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[Content Guide] Recently, in addition to the requirements of small and thin, energy-saving, and low-noise in the past, electronic equipment is expected to achieve ecological needs by preventing global warming. Under such market demand, the LED bulbs that have been popular since 2009 have become small and thin, and have achieved high eco-friendship due to their long service life. The electronic components mounted on them are also required to be small and thin. It has a long service life.

LED bulbs are equipped with a small power supply of about 10W, mainly using electrolytic capacitors and film capacitors to achieve a smooth function, but the use of small and longer-life ceramic capacitors is also increasing. Ceramic capacitors with higher electrostatic capacity than conventional ceramic materials, this paper will introduce its characteristics, and introduce the recommended circuit for power supply of other electronic devices based on LED bulbs.

New material ceramic capacitor performance

The properties of the new material ceramics are compared with the conventional materials, and the Curie point is transferred to the low temperature side, so that it exhibits a paraelectric phase at normal temperature (25 ° C). Therefore, the new material product can achieve the following performance compared with the conventional product.

The reduction rate of the capacitance value when the DC voltage is applied is small, and the high effective capacitance value (the capacity when the DC voltage is applied) is ensured. It ensures that the capacitance is twice that of conventional materials when DC600V is applied.

The loss is small, allowing a large ripple current. The ripple current is allowed to be approximately 1.6 times at a frequency of f = 250 kHz.

Murata's standard for allowing ripple current is that the ambient temperature is below 25 degrees and can be energized until the capacitor self-heating temperature reaches 20 degrees. If the electrostatic capacity is 1 & m ICro; F products, the frequency f = 250 kHz, the current resistance of 2.9Arms compared to the traditional material products, the new material is 4.7Arms.

When the DC voltage is applied, the mechanical strain is relatively small, and the click (sound pressure level) is also small. Compared to traditional materials, the new material has a sound pressure level of only one-fifth. The piezoelectric effect of new material ceramics is small. Therefore, mechanical vibration caused by changes in electrical signals is less likely to occur.

A reduction in sound pressure level of 6 dB means that the sound pressure becomes 1/2, and the sound pressure level of the new material capacitor is 15 dB lower than that of the conventional material, and the sound pressure is 1/5.

Product overview and introduction to the use of circuits

In October 2010, the commercialization of new materials as shown in Figure 5 was completed. In addition, regarding the maximum electrostatic capacity that can be obtained, the lead type or the metal terminal type, due to the commercialization of two capacitor-stacked products, the product with a rated voltage of DC250V is 2μF (=1μF×2), and the product of DC450V is 1.1μF. The product of (=0.56μF×2) and DC630V is 0.54μF (=0.27μF×2). In addition, the temperature characteristic of the new material ceramic capacitor is X7T (conventional material is X7R).

The general power circuit diagram of the LED bulb is shown in Figure 6.

The performance of the new material product is as shown on the previous page. The summary is as follows:

1. Ensures a higher effective capacitance value than conventional products.

2. The power is allowed to be large, and the ripple current tolerance is large.

A small power supply such as an LED bulb can be used as a smoothing function in addition to noise countermeasures, thus forming an optimum design such as C4 and C5 of FIG.

The specific capacitance value is selected for the Japanese market: when the input voltage is AC100V, the upper and lower potential difference of the rectifier circuit is 140Vo-p (=100×&raDIC; 2), so the product with rated voltage of DC250V can be selected to the maximum. The capacitance value is 2μF. Similarly, products for the global market: when the input voltage is AC240V, the upper and lower potential difference is 340Vo-p (=240×√2), and the rated voltage is DC450V. The maximum capacitance value of the product is 1.1μF, and the rated voltage is DC630V. The maximum capacitance value that can be selected for the product is 0.54μF.

In addition, in addition to the LED bulb, in order to improve the harmonics and power factor of the LED lighting device, a PFC (Power Factor Improvement) circuit is added after the rectifier circuit. Because the new material product has less loss than the conventional product, it can be used as a PFC input capacitor with excellent high-frequency ripple current tolerance.

In addition, other capacitors that can be used for C1.C2 and the like are shown in FIG.

The capacitors of the new materials have been developed and commercialized with the goal of low loss and high capacity. In addition to noise countermeasures, its use in circuits has developed products that are most suitable for smoothing applications. In the future, in addition to providing the necessary technical data (allowing ripple current data, etc.), we will provide more information for your convenience.