JP2006238310A - Lc composite component and noise suppressing circuit using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an LC composite component, and a noise suppressing circuit using the same, suitable for downsizing the noise suppression circuit. <P>SOLUTION: An LC composite component 20 has a structure in which a plurality of toroidal ferrite cores 21 and a plurality of electrode plates 22 are alternately laminated. The electrode plate 22 is provided with a lead terminal 22R protruding from one end of its outer periphery. The lead terminals 22R alternately face the opposite side, and three lead terminals 22R drawn to the left are connected to the ground while two terminals 22R drawn to the right are connected to connection points P3 and P4 on the power supply line. The ferrite core 21 and conductive wires 23 and 24 for a coil constitute a common mode choke coil 12 shown in Fig. 1. A plurality of electrode plates 22 so provided on both sides as to sandwich the ferrite core 21 constitute capacitors Cy1 and Cy2 for a "Y-capacitor". <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an LC composite component and a noise suppression circuit, and more particularly to an LC composite component in which a coil and a capacitor are integrally formed and a noise suppression circuit using the LC composite component.

  Conventionally, a combination of a coil and a capacitor has been widely used as a noise suppression circuit that suppresses noise in the power supply line. Among these, a noise suppression circuit using a common mode choke coil is effective in suppressing common mode noise generated from the switching power supply. In the noise suppression circuit, a bypass capacitor called “Y-con” is also provided. Thereby, common mode noise can be further suppressed and filter characteristics can be improved.

By the way, a capacitor such as a chip capacitor or a lead capacitor is usually used for the Y capacitor, and a mounting area for the capacitor must be secured on the circuit board separately from the common mode choke coil. It has become a problem for crystallization. In order to reduce the size of the noise suppression circuit, a method has also been proposed in which a coil and a capacitor are integrally arranged to reduce the mounting space (see Patent Document 1). However, it cannot be said that such a method contributes sufficiently to the miniaturization of the noise suppression circuit.
JP 2001-285005 A

  As described above, the conventional noise suppression circuit has to secure a mounting area of the Y capacitor and other necessary capacitors on the circuit board, and has been one of the factors that hinder the miniaturization of the noise suppression circuit. In recent years, demands for downsizing and high performance of electronic components and electronic devices have become more and more severe, and further downsizing of noise suppression circuits has been demanded.

  Accordingly, an object of the present invention is to provide an LC composite component suitable for downsizing a noise suppression circuit and a noise suppression circuit using the LC composite component.

  The object of the present invention is achieved by an LC composite component comprising a magnetic core, electrode plates provided on both sides of the magnetic core, and a coil conductor wound around the magnetic core.

  In the present invention, it is preferable that the magnetic core and the electrode plate have a toroidal shape.

  In this invention, it is preferable that the said coil conducting wire is integrally wound with respect to the said magnetic core and the said electrode plate.

  In the present invention, it is preferable that a plurality of the magnetic cores are stacked in the axial direction, and the electrode plate is sandwiched between these magnetic cores.

  The object of the present invention is also achieved by a noise suppression circuit configured using the LC composite component as described above.

  In the present invention, it is preferable that the magnetic core and the coil conductor of the LC composite electronic component function as a common mode choke coil, and the electrode plate functions as a Y-con.

  In the present invention, it is preferable that an intermediate tap is provided in the common mode choke coil, and a resonance circuit is inserted between the intermediate tap and the grant.

  According to the present invention, the inductor and the capacitor are integrally formed by alternately laminating the toroidal magnetic core and the electrode plate and winding the coil conductor around the laminated body. In a noise suppression circuit that requires a capacitor, it is not necessary to separately mount a capacitor as in the prior art, so that the mounting area of components can be reduced, which contributes to a reduction in the size of the noise suppression circuit.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a circuit diagram showing a configuration of a noise suppression circuit according to a preferred embodiment of the present invention.

  As shown in FIG. 1, the noise suppression circuit 10 includes an X capacitor 11, a common mode choke coil 12, and a Y capacitor 13 inserted between a pair of power supply lines A1-A2 and B1-B2. .

  The X capacitor 11 is also called an across line capacitor and plays a role of reducing normal mode noise. The X capacitor 11 includes a capacitor Cx having one end connected to one power supply line A1-A2 and the other end connected to the other power supply line B1-B2. The capacitance of the capacitor Cx needs to be set to an appropriate value because the reactive current increases if it is too large.

  The common mode choke coil 12 is a filter element that plays a role of allowing a normal mode signal to pass while suppressing common mode noise. The first inductor L11 and the second inductor L12 that constitute the common mode choke coil 12 are both wound around a common core M1 and are electromagnetically coupled to each other so as to suppress common mode noise in cooperation. That is, in the windings, the magnetic fluxes induced in the core M1 are canceled by the currents flowing through the windings when a normal mode current flows, and the magnetic fluxes induced in the core M1 when a common mode current flows. Are wound in the same direction.

  Inductors L11 and L12 constituting the common mode choke coil 12 are provided with intermediate taps P1 and P2, respectively, and a resonance circuit 14 is inserted between the intermediate taps P1 and P2 and the ground GND. In the present embodiment, it is constituted by a series circuit of two capacitors C21 and C22 prepared separately for each of the intermediate taps P1 and P2 and a common inductor L3 for these capacitors C21 and C22. . Thus, when the resonance circuit 14 is provided between the intermediate taps of the inductors L1 and L2 and the ground, the common mode noise component is more effectively suppressed in the vicinity of the resonance point. Therefore, by setting the resonance point to a desired frequency band, for example, it is possible to more effectively suppress noise components in the frequency band.

  The Y capacitor 13 is also called a line bypass capacitor and plays a role of suppressing common mode noise. The Y capacitor 13 includes a capacitor Cy1 connected to the connection point P3 on one power supply line A1-A2, and a capacitor Cy2 connected to the connection point P4 on the other power supply line B1-B2. The other ends of the capacitors Cy1 and Cy2 are both connected to the ground GND. The capacitances of the capacitors Cy1 and Cy2 need to be set to appropriate values because leakage current increases if the capacitance is too large.

  In the noise suppression circuit 10 of this embodiment, the Y-con 13 and the common mode choke coil 12 are configured using one LC composite component. Hereinafter, the LC composite component will be described in detail.

  FIG. 2 is a perspective view schematically showing the structure of the LC composite component. FIG. 3 is an exploded perspective view of the LC composite component shown in FIG. 2 and shows a state before the coil conductor is wound.

  As shown in FIGS. 2 and 3, the LC composite component 20 has a structure in which a plurality of ferrite cores 21 and a plurality of electrode plates 22 are alternately stacked. In the present embodiment, four ferrite cores 21A to 21D are stacked in the central axis Z direction, and the electrode plate 22 is placed between the ferrite cores 21 and also on the outermost ferrite cores 21A and 21D. Is provided. When the total number of electrode plates 22 is generalized, (n + 1) electrode plates 22 are required for n ferrite cores.

  The ferrite core 21 and the electrode plate 22 are both toroidal, and the electrode plate 22 includes a lead terminal 22R protruding from one end of the outer periphery thereof. Each lead terminal 22R is alternately directed to the opposite side, and in this embodiment, three lead terminals 22R drawn to the left side of the figure are connected to the connection point P5 (that is, the ground) shown in FIG. The two terminals 22R drawn to the right are connected to the connection points P3 and P4 on the power supply line shown in FIG. It is preferable that the lead-out direction of the lead terminal 22R is unified to some extent. This is because the lead terminal generates a slight inductance, but the lead terminals drawn out in the same direction can be regarded as a parallel connection of inductances, and the inductance can be reduced as a whole. Therefore, it is preferable that the drawing directions of the three lead terminals 22R drawn to the left side in the drawing are all matched, and the drawing directions of the two lead terminals 22R drawn to the right side are also matched.

  Coil wires 23 and 24 are wound around the laminate of the ferrite core 21 and the electrode plate 22. The coil conductors 23 and 24 are integrally wound around the ferrite core 21 and the electrode plate 22 that are alternately stacked. The coil conductors 23 and 24 are wound in a direction in which magnetic fluxes generated in the respective windings are strengthened by the common mode current. The coil conductor 23 is provided with an intermediate tap P1, and the coil conductor 24 is provided with an intermediate tap P2.

  When the LC composite component 20 configured as described above is used in the noise suppression circuit 10 of FIG. 1, the common mode choke coil 12 illustrated in FIG. 1 is configured by the ferrite core 21 and the coil conductors 23 and 24. Capacitors Cy1 and Cy2 for Y-con are formed by a plurality of electrode plates 22 provided on both sides of the ferrite core 21 so as to sandwich the ferrite core 21. Specifically, the capacitor Cy1 is configured by the electrode plates 22A, 22B, and 22C, and the capacitor Cy2 is configured by 22C, 22D, and 22E.

  As described above, according to the present embodiment, since the inductor for the common mode choke coil and the capacitor for the Y capacitor are integrally configured, the capacitor for the Y capacitor is separately mounted as in the conventional case. Compared to the case, the board area required for mounting components can be reduced, and the noise suppression circuit can be reduced in size. In addition, when the ferrite core is overheated, its magnetic permeability may change and the characteristics of the common mode choke coil may be deteriorated. However, when the electrode plate is in close contact with the ferrite core as in this embodiment. Since the heat generated in the ferrite core can be released to the outside through the electrode plate, the characteristic deterioration of the common mode choke coil can be prevented.

  FIG. 4 is a circuit diagram showing a noise suppression circuit according to the second embodiment of the present invention.

  As shown in FIG. 4, the noise suppression circuit 30 does not include the resonance circuit 14 connected to the X tap 11 or the intermediate tap of the common mode choke coil 12, and includes only the common mode choke coil 12 and the Y contact 13. This is different from the noise suppression circuit 10 of FIG. The other points are the same as those of the noise suppression circuit 10.

  Also in the noise suppression circuit 30 of the present embodiment, the LC composite component 20 shown in FIGS. 2 and 3 can be used. However, in the case of this embodiment, an intermediate tap is unnecessary. By using the LC composite component 20, the inductors L11 and L12 for the common mode choke coil and the capacitors Y1 and Cy2 for the Y capacitor are configured integrally. Compared with the case of separate mounting, the board area required for mounting components can be reduced, which contributes to the miniaturization of the noise suppression circuit. Further, it is possible to prevent deterioration of characteristics due to heat generation of the ferrite core.

  FIG. 5 is a perspective view showing another example of the LC composite component. Or it is the exploded perspective view of FIG. 6, Comprising: The state before winding conducting wire for coils is shown.

  As shown in FIGS. 5 and 6, the LC composite component 40 is composed of two ferrite cores 21 (21A, 21B) and three electrode plates 22 (22A, 22B, 22C) as described above. This is different from the LC composite part 20. In this case, the lead terminal protruding leftward is connected to the ground (P5), and the lead terminal protruding rightward is connected to the connection points P3 and P4 on the power supply line.

  The stacked structure shown in FIGS. 5 and 6 is the minimum number of components when the LC composite component is used as the common mode choke coil 12 and the Y capacitor 13 in the noise suppression circuit 10 or 20. As shown in FIGS. 2 and 3, the number of ferrites 21 and electrode plates 22 can be further increased as shown in FIGS. 2 and 3. If the ferrite core 21 is made as thin as possible to increase the number of layers, the filter characteristics can be improved. Can do. However, if the thickness is too thin, the strength of the ferrite core will be weak, and if it is stacked too much, it will not be possible to meet the demand for a low-profile mounting component. It may be determined as appropriate in consideration of the above.

  As described above, also in this embodiment, the inductor for the common mode choke coil and the capacitor for the Y capacitor are integrally formed, and therefore, the capacitor for the Y capacitor is separately mounted as in the prior art. Compared to the case, the board area required for mounting components can be reduced, and the noise suppression circuit can be reduced in size. In addition, it is possible to prevent deterioration of characteristics due to heat generation of the ferrite core.

  In the above embodiment, the LC composite component suitable for the noise suppression circuit including the common mode choke coil and the Y-con has been described. It is also possible to apply to the noise suppression circuit 50.

  FIG. 8 is a perspective view schematically showing the structure of the LC composite component used in the noise suppression circuit 50. FIG. 9 is an exploded perspective view showing a state before the coil conductor is wound.

  As shown in FIGS. 8 and 9, the LC composite component 60 has the simplest structure in which one ferrite core 21 is sandwiched between two electrode plates 22A and 22B. A coil lead wire 23 is integrally wound. One end of the coil conductor 23 is connected to the lead terminal of one electrode plate 22A. The lead terminal of the electrode plate 22B, the lead terminal of the electrode plate 22A, and the other end of the coil conductor 23 of the LC composite component 60 configured as described above correspond to the connection points P5, P6, and P7 in FIG. ing.

  Also in this embodiment, since the inductor and the capacitor are integrally formed, the board area required for mounting the component can be reduced compared with the case where the capacitor is separately mounted, and the noise suppression circuit can be reduced in size. It can contribute to the conversion. Further, it is possible to prevent deterioration of characteristics due to heat generation of the ferrite core.

  10A to 10C are perspective views showing still other examples of the LC composite component.

  In each of the LC composite parts 70, 80, and 90 shown in FIGS. 10A to 10C, a rectangular ferrite core 71 is sandwiched between two rectangular electrode plates 72A and 72B, and a coil is formed on the ferrite core 71. This is common in that the conductive wire 73 is wound. Among them, the LC composite component 70 in FIG. 10A is obtained by winding a coil lead wire 73 on a ferrite core 71 having electrode plates 72A and 72B superimposed thereon, and the LC composite component 80 in FIG. 10B. On the contrary, the electrode plates 72A and 72B are stacked on the ferrite core 71 on which the coil conducting wire 73 is wound. Further, FIG. 10C is a diagram in which the position where the electrode plates 72 </ b> A and 72 </ b> B are superimposed on the ferrite core 71 and the position where the coil conductor 73 is wound are shifted. Any of these can be applied to the LC filter circuit 50 of FIG. 7, and since the inductor and the capacitor are integrally formed, the board area required for mounting the components can be reduced as compared with the case where the capacitors are separately mounted. It is possible to reduce the size and contribute to the miniaturization of the noise suppression circuit. Further, it is possible to prevent deterioration of characteristics due to heat generation of the ferrite core.

  The present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention, and these are also included in the scope of the present invention. Needless to say.

  For example, in the above embodiment, the case where the ferrite core is used as the magnetic core for winding the coil wire is described. However, the present invention is not limited to this, and any material having a high magnetic permeability can be used. It may be a magnetic core.

  In the above embodiment using the common mode choke coil, the capacitor portion of the LC composite component is used as the capacitor for the Y capacitor. However, the present invention is not limited to this, and for example, FIG. The capacitors C21 and C22 of the resonance circuit 14 may be used. Furthermore, the number of electrode plates may be increased and used for both the Y capacitor and the capacitor for the resonance circuit 14.

FIG. 1 is a circuit diagram showing a configuration of a noise suppression circuit according to a preferred embodiment of the present invention. FIG. 2 is a perspective view schematically showing the structure of the LC composite component. FIG. 3 is an exploded perspective view of the LC composite component of FIG. 2 and shows a state before winding the coil conductor. FIG. 4 is a circuit diagram showing a noise suppression circuit according to the second embodiment of the present invention. FIG. 5 is a perspective view showing another example of the LC composite component. FIG. 6 is an exploded perspective view of the LC composite component shown in FIG. 5 and shows a state before winding the coil conductor. FIG. 7 is a circuit diagram showing still another example of the noise suppression circuit. FIG. 8 is a perspective view schematically showing the structure of the LC composite component used in the noise suppression circuit of FIG. FIG. 9 is an exploded perspective view of the LC composite component of FIG. 7 and shows a state before winding the coil conductor. 10A to 10C are perspective views showing still other examples of the LC composite component.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Noise suppression circuit 11 X-con 12 Common mode choke coil 13 Y-con 14 Resonance circuit 21 Ferrite core 21A-21D Ferrite core 22 Electrode plate 22A-22E Electrode plate 22R Lead terminal 23 of an electrode plate Coil lead 24 Coil lead 30 Noise Suppression circuit 40 LC composite component 50 Noise suppression circuit 60 LC composite component 70 LC composite component 71 Ferrite core 72A Electrode plate 72B Electrode plate 80 LC composite component 90 LC composite component A1-A2 Power supply line A1-A2 Power supply line Cx Capacitor for X component Cy1 Y-con capacitor Cy2 Y-con capacitor L11 Inductor L12 Inductor L3 Inductor M1 Core P1 Intermediate tap P2 Each intermediate tap P5, P6, P7 Connection point

Claims (7)

  An LC composite component comprising a magnetic core, electrode plates provided on both sides of the magnetic core, and a coil conductor wound around the magnetic core.   The LC composite component according to claim 1, wherein the magnetic core and the electrode plate have a toroidal shape.   The LC composite component according to claim 1, wherein the coil conductor is integrally wound around the magnetic core and the electrode plate.   The LC composite component according to any one of claims 1 to 3, wherein a plurality of the magnetic cores are stacked in an axial direction, and the electrode plate is sandwiched between the magnetic cores.   The noise suppression circuit comprised using the LC composite component of any one of Claims 1 thru | or 4.   The noise suppression circuit according to claim 5, wherein the magnetic core and the coil conductor of the LC composite electronic component function as a common mode choke coil, and the electrode plate functions as a Y-con.   The noise suppression circuit according to claim 6, wherein an intermediate tap is provided in the common mode choke coil, and a resonance circuit is inserted between the intermediate tap and the grant.

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