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Background and Details



With rising concern toward global environmental issues and energy issues in recent years, the automobile market is endorsing practical applications of Hybrid Electric Vehicles (HEV) and Electric Vehicles (EV) . Since thermal resistance is a key requirement of electronic components for HEV and EV applications, there is a demand for capacitors that are resistant to high temperatures. In response to this demand, Murata has developed monolithic ceramic capacitors that have high ripple-current resistance (low self-heat generation) using newly developed ceramic materials.



There is also an increasing demand for small and long-life ceramic capacitors with high capacitance as a replacement for electrolytic capacitors and film capacitors used as smoothing capacitors. To meet this demand, Murata uses new materials to assure a high effective capacitance by suppressing the characteristic that lowers electrostatic capacity when a DC bias is applied (during operation) .



Furthermore, there is a possibility that cracks may occur in a capacitor element and solder joints of mounted components due to thermal stress or vibration/mechanical impact. Therefore, crack prevention measures must be provided for automobiles, general electronic devices, and industrial electronic devices that are used under such conditions. Murata has reduced the effects of impact to chip elements and solder joints of mounted components by attaching metal terminals with an elastic action to the capacitors.



Features



High ripple-current resistance



Since it has low loss and a high allowable current capacity, the heat generation of the capacitor (self-heat generation) can be reduced at the time of passing current.



Example: (See the upper right graph below.) The new material product has approximately 1.6 times higher allowable current capacity at a frequency (f) of 250kHz. In the case of products with a capacitance of 1μF when the heating temperature is 20°C at a frequency (f) of 250kHz, the allowable current capacity of capacitors made of conventional materials is 2.9Arms whereas that of capacitors made of the new material is 4.7Arms.

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High effective capacitance



It is possible to reduce the drop in capacitance while a DC bias is applied, as well as assure high effective capacitance value.



Example: Approximately twice higher capacitance is assured when DC250V is applied.

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Applications



General-purpose applications (KR3 series)

1.Smoothing and EMI filter for LED lighting

2.Used for the Power Factor Correction (PFC) circuit in the switching power supplies and AC adaptor

3.DC-DC converter for general electronic devices



Automotive applications (KC3 series)

1.Used for drive system control in equipment such as engines and ECUs

2.Used for other drive system controls and safety devices