JP2010130312A - Surface-mount pulse transformer, and surface-mount pulse transformer with common mode filter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the number of winding wires to be wind around one drum type core in a surface-mount pulse transformer. <P>SOLUTION: The surface-mount pulse transformer is provided with: a drum type core 11A around which winding wires S1A, S2A are wound in the same winding direction to each other; and a drum type core 11B around which winding wires S1B, S2B are wound in the same winding direction to each other, wherein an end part on one end side of the drum type core 11A of the winding wire S1A is connected to an input terminal IN+ on the positive side, an end part on the other end side of the drum type core 11B of the winding wire S1B is connected to an input terminal IN- on the negative side, an end part on the other end side of the drum type core 11A of the winding wire S1A and an end part on one end side of the drum type core 11B of the winding wire S1B are connected to an intermediate tap CT on the input side, an end part on one end side of the drum type core 11A of the winding wire S2A is connected to an output terminal OUT+ on the positive side, an end part on the other end side of the drum type core 11B of the winding wire S2B is connected to an output terminal OUT- on the negative side, and an end part on the other end side of the drum type core 11A of the winding wire S2A and an end part on one end side of the drum type core 11B of the winding wire S2B are connected to an intermediate tap CT on the output side, respectively. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a surface mount pulse transformer and a surface mount pulse transformer with a common mode filter.

  When connecting a device such as a personal computer to a network such as a LAN or a telephone network, it is necessary to protect the device from ESD (ElectroStatic Discharge) and high voltage entering through a cable. Therefore, a pulse transformer is used as a connector constituting the connection point between the cable and the device.

  A conventionally used pulse transformer is formed by winding a primary coil and a secondary coil around a donut-shaped magnetic core (toroidal core) (see, for example, Patent Document 1), and among the voltages applied to the primary coil Only the AC component (pulse) is transmitted to the secondary coil. Since the direct current component is not transmitted to the secondary coil, the pulse transformer can block ESD and high voltage.

  By the way, in recent years, pulse transformers are also required to be miniaturized and surface-mounted. For this reason, an example using a drum core instead of a toroidal core has appeared. Such a pulse transformer is called a surface mount type pulse transformer.

  FIG. 10 shows a typical configuration example of a surface mount pulse transformer. FIG. 11 is a diagram showing an equivalent circuit of the surface mount pulse transformer 1 shown in FIG.

  As shown in FIG. 10, the surface mount type pulse transformer 1 has a drum core 2, and the drum core 2 is provided at both ends of the core portion 2a for winding the winding and the core portion 2a. And the flanges 2b and 2c. Three terminal electrodes P1 to P3 and P4 to P6 are provided on the upper surfaces of the flange portions 2b and 2c, respectively.

  As shown in FIGS. 10 and 11, windings S1 to S4 are wound around the core 2a, and both ends S1a and S1b of the winding S1 are connected to terminal electrodes P1 and P2 and both ends of the winding S2, respectively. S2a and S2b are connected to terminal electrodes P2 and P3, both ends S3a and S3b of winding S3 are connected to terminal electrodes P4 and P5, and both ends S4a and S4b of winding S4 are connected to terminal electrodes P5 and P6, respectively.

The surface-mounted pulse transformer 1 is a balanced input / output circuit, and as shown in FIG. 11, the terminal electrodes P1 and P3 become a balanced input plus side terminal IN + and minus side terminal IN-, respectively. Further, the terminal electrodes P4 and P6 become the positive side terminal OUT + and the negative side terminal OUT− of the balanced output, respectively. Each winding is wound around the core part 2a so that an induced current flows from the terminal OUT + to the terminal OUT- when a current flows from the terminal IN + to the terminal IN-. The terminal electrodes P2 and P5 serve as intermediate taps CT on the input side and output side, respectively.
JP-A-7-161535

  However, in the conventional surface mount type pulse transformer, as many as four windings must be wound around one drum core, and the winding operation becomes complicated, and the number of terminal electrodes provided on one drum core is also large. There was a problem that it would increase.

  Accordingly, one of the objects of the present invention is to provide a surface mount pulse transformer and a surface mount pulse transformer with a common mode filter that can reduce the number of windings wound around one drum core.

  In order to achieve the above object, a surface mount pulse transformer according to the present invention includes a first drum core in which first and third windings are wound in the same winding direction, and second and fourth windings. And a second drum-type core wound in the same winding direction, and an end on one end side of the first drum-type core of the first winding is a plus-side input terminal The other end of the second drum core of the second winding is connected to the negative input terminal, and the other end of the first drum core of the first winding. An end portion on the end side and an end portion on one end side of the second drum type core of the second winding are connected to an input side intermediate tap, and the first drum type core of the third winding is connected The end on one end side is connected to the plus side output terminal, and the end on the other end side of the second drum type core of the fourth winding is minus Connected to the output terminal, the end of the third winding on the other end side of the first drum core and the end of the fourth winding on the one end side of the second drum core are output. It is connected to the side intermediate tap.

  According to the present invention, since the pulse transformer can be constituted by the first and second drum cores wound with only two windings, the number of windings wound around one drum core can be reduced. . In addition, since the first winding and the fourth winding, and the second winding and the third winding are not magnetically coupled, it is easy to keep the characteristics of the pulse transformer good.

  The surface mount pulse transformer with a common mode filter according to the present invention includes a first drum core in which the first and third windings are wound in the same winding direction, and the second and fourth windings. A second drum core in which the windings are wound in the same winding direction; and a third drum core in which the fifth and sixth windings are wound in the same winding direction. An end of the third winding on one end side of the first drum-type core and an end of the fifth winding on the one end side of the third drum-type core are connected, and 4 is connected to an end portion on the other end side of the second drum type core of the fourth winding and an end portion on the one end side of the third drum type core of the sixth winding. One end of the first drum core of the wire is connected to a positive input terminal, and the other end of the second drum core of the second winding is connected Is connected to the negative side input terminal, and the end of the first winding on the other end side of the first drum core and the end of the second winding on the second drum core of the second winding are connected. An end portion is connected to the input-side intermediate tap, and an end portion on the other end side of the first drum-type core of the third winding and an end side of the second drum-type core of the fourth winding The other end of the third drum core of the fifth winding is connected to the plus output terminal, and the end of the sixth winding is connected to the output side intermediate tap. The other end of the third drum core is connected to the negative output terminal.

  According to the present invention, in a surface-mount type pulse transformer, the number of windings wound around one drum-type core can be reduced, and three common mode filters having the same configuration are arranged on a substrate to provide a surface with a common mode filter. A mounting type pulse transformer can be configured.

  Thus, according to the present invention, in the surface mount pulse transformer, the number of windings wound around one drum core can be reduced.

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

  Since the surface mount type common mode filter is used in the present embodiment, the surface mount type common mode filter used in the present embodiment will be described prior to the description of the surface mount type pulse transformer according to the present embodiment.

  FIG. 1 is a schematic perspective view showing an external structure of a surface-mounted common mode filter 10 used in the present embodiment. As shown in the figure, the surface mount type common mode filter 10 includes a drum core 11, a plate core 12 attached to the drum core 11, and windings S1 and S2 wound around the drum core 11. It has.

  The drum core 11 includes a rod-shaped core part 11a and flanges 11b and 11c provided at both ends of the core part 11a, and has a structure in which these are integrated. The drum core 11 is used by being installed on a substrate, and is affixed to the substrate with the upper surfaces 11bs and 11cs of the flange portions 11b and 11c facing the substrate. The plate-like core 12 is fixed to the lower surfaces of the flange portions 11b and 11c (surfaces opposite to the upper surfaces 11bs and 11cs).

  The drum core 11 and the plate core 12 are made of a magnetic material having a relatively high magnetic permeability, for example, a sintered body of Ni—Zn ferrite or Mn—Zn ferrite. Note that a magnetic material having a high magnetic permeability such as Mn—Zn-based ferrite usually has a low specific resistance and conductivity.

  Two terminal electrodes E1 and E2 are formed on the upper surface 11bs of the flange portion 11b, and two terminal electrodes E3 and E4 are formed on the upper surface 11cs of the flange portion 11c. The terminal electrodes E1 and E2 are arranged in this order from one end side in the x direction (direction perpendicular to the magnetic core direction (y direction) in the substrate surface) shown in FIG. Similarly, the terminal electrodes E3 and E4 are also arranged in this order from one end side in the x direction. The end portions of the windings S1 and S2 are connected to the terminal electrodes E1 to E4 by thermocompression bonding.

  The windings S1 and S2 are coated conductors and are wound around the winding core portion 11a in the same winding direction to constitute a coil conductor. The number of turns of the windings S1, S2 is also the same. As a specific winding method, a two-layer structure as shown in FIG. 1 or a so-called bifilar winding in which the windings S1 and S2 are alternately arranged and wound may be used. One end (end on the flange 11b side) S1a and the other end (end on the flange 11c side) S1b of the winding S1 are connected to the terminal electrodes E1 and E3, respectively. Further, one end (end on the flange 11b side) S2a and the other end (end on the flange 11c side) S2b of the winding S2 are connected to the terminal electrodes E2 and E4, respectively.

  The above is the description of the surface mount type common mode filter 10 used in the present embodiment. Next, the surface mount pulse transformer according to the first embodiment of the present invention will be described.

  FIG. 2 is a schematic diagram of the surface mount pulse transformer 20 according to the first embodiment. 2 is a perspective view of the substrate on which the surface mount pulse transformer 20 is installed as seen from the back side of the installation surface. FIG. 3 is an equivalent circuit diagram of the surface mount pulse transformer 20. Hereinafter, description will be given with reference to these drawings.

  As shown in FIG. 2, the surface mount pulse transformer 20 uses two surface mount common mode filters 10. In the following description, “A” and “B” may be added at the end of the reference numerals, but “A” indicates a configuration related to the first surface-mounted common mode filter 10, and “B” indicates the second The structure regarding the surface mount type common mode filter 10 is shown.

  As shown in FIG. 2, the terminal electrode E3A and the terminal electrode E1B, and the terminal electrode E4A and the terminal electrode E2B are short-circuited. That is, the surface-mounted common mode filter 10A and the surface-mounted common mode filter 10B are connected in series.

  Further, the terminal electrodes E1A and E3B are respectively used as a positive input terminal IN + and a negative input terminal IN- for balanced input, and the terminal electrodes E2A and E4B are respectively used as a positive output terminal OUT + and a negative output terminal OUT- for balanced output. . Further, the terminal electrode E3A (terminal electrode E1B) and the terminal electrode E4A (terminal electrode E2B) are used as intermediate taps CT on the input side and output side, respectively.

  By doing so, as shown in the equivalent circuit diagram of FIG. 3, the two surface mount type common mode filters 10 </ b> A and 10 </ b> B function as one surface mount type pulse transformer 20. That is, winding S1A (first winding) constitutes a positive input side coil, winding S1B (second winding) constitutes a negative input side coil, and winding S2A (third winding). Constitutes a plus output side coil, and winding S2B (fourth winding) constitutes a minus output side coil.

  As is apparent from FIGS. 2 and 3, the surface-mount pulse transformer 20 does not require four windings to be wound around the drum-type core. The number of windings wound around one drum core can be reduced.

  FIG. 4 is a plan view of the printed circuit board 50 on which the surface mount pulse transformer 20 is mounted.

  Regions 50A and 50B on the printed circuit board 50 shown in FIG. 4 are mounting regions for the surface-mounted common mode filters 10A and 10B, respectively. As shown in the figure, four land patterns 51A to 54A and 51B to 54B are provided in the mounting areas 50A and 50B, respectively. The land patterns 51A and 53B are patterns connected to the pair of balanced transmission lines STL1 and SBL1, and are connected to the terminal electrodes E1A and E3B, respectively. The land patterns 52A and 54B are patterns connected to the balanced transmission lines STL2 and SBL2, and are connected to the terminal electrodes E2A and E4B, respectively. The land patterns 53A, 54A, 51B, and 52B are short-circuited by the wiring pattern on the substrate 50 and connected to the ground GND. The land patterns 53A, 54A, 51B, and 52B are connected to the terminal electrodes E3A, E4A, E1B, and E2B, respectively.

  With such a layout, the balanced transmission lines STL1, SBL1 and the balanced transmission lines STL2, STL2 can be formed in parallel and linearly. This eliminates the need for bypassing the wiring pattern on the printed circuit board, so that the occupied area of the wiring pattern does not increase more than necessary, and the symmetry of the wiring pattern can be ensured. As a result, it is possible to simultaneously reduce the size of the entire apparatus and improve the signal quality.

  In FIG. 4, the land patterns 53A, 54A, 51B, and 52B are all grounded. However, when the intermediate taps on the input side and the output side are separately connected to other circuits, the land patterns 53A, 51B and The land patterns 54A and 52B may be connected to the respective lines.

  Since the substrate 50 is configured as described above, by mounting the surface mount pulse transformer 20 on the substrate 50, the connection between the terminal electrodes of the surface mount pulse transformer 20 and the connection of input / output and intermediate taps can be performed. 50 can be realized by the wiring pattern on 50.

  As described above, according to the surface mount pulse transformer 20, the number of windings wound around one drum core can be reduced.

  In the surface mount pulse transformer 20, the winding S1A and the winding S2B, and the winding S1B and the winding S2A are not magnetically coupled. In a surface mount type pulse transformer that winds four windings around one drum core, the four windings are magnetically coupled to each other. Therefore, when winding each winding, the positions of the windings are accurately positioned. Although it is necessary to determine, such a need does not exist in the surface mount type pulse transformer 20. That is, the surface-mount pulse transformer 20 can easily maintain good characteristics as a pulse transformer.

  Next, a surface mount pulse transformer according to a second embodiment of the present invention will be described. FIG. 5 is a schematic diagram of a surface mount pulse transformer 30 according to the second embodiment. FIG. 5 is a perspective view of the substrate on which the surface mount pulse transformer 30 is installed as seen from the back side of the installation surface. FIG. 6 is an equivalent circuit diagram of the surface mount pulse transformer 30.

  The surface mount pulse transformer 30 is a surface mount pulse transformer with a mon mode filter in which a common mode filter is added to the output side of the surface mount pulse transformer 20. Hereinafter, description will be made centering on additional points from the surface mount pulse transformer 20.

  As shown in FIG. 5, the surface mount pulse transformer 30 uses three surface mount common mode filters 10. Two of these are surface-mounted common mode filters 10 </ b> A and 10 </ b> B used in the surface-mounted pulse transformer 20. In the following description, there is a case where “C” is appended to the end of the reference symbol, but this “C” indicates a configuration related to the added surface mount type common mode filter 10.

  As shown in FIG. 5, the terminal electrode E2A and the terminal electrode E2C, and the terminal electrode E4B and the terminal electrode E1C are short-circuited.

  The terminal electrodes E1A and E3B are the balanced input plus input terminal IN + and minus input terminal IN-, respectively, and the terminal electrodes E4C and E3C are the balanced output plus output terminal OUT + and minus output terminal OUT-, respectively. . Further, the terminal electrode E3A (terminal electrode E1B) and the terminal electrode E4A (terminal electrode E2B) are used as intermediate taps CT on the input side and output side of the surface mount pulse transformer 20, respectively.

  By doing so, the surface-mounted common mode filter 10C functions as a common mode filter connected in series to the output side of the surface-mounted pulse transformer 20 as shown in the equivalent circuit diagram of FIG. That is, the winding S2C (fifth winding) constitutes the plus side coil of the common mode filter, and the winding S1C (sixth winding) constitutes the minus side coil.

  FIG. 7 is a plan view of the printed circuit board 50 on which the surface mount pulse transformer 20 is mounted.

  Regions 50A to 50C on the printed circuit board 50 shown in FIG. 7 are mounting regions for the surface mount type common mode filters 10A to 10C, respectively. Since the configurations in the mounting areas 50A and 50B are the same as those in the first embodiment, description thereof will be omitted. Four land patterns 51C to 54C are provided in the mounting area 50C. The land patterns 51C and 52C are short-circuited with the land patterns 54B and 52A by the wiring pattern on the substrate 50, respectively. The balanced transmission lines STL2 and SBL2 connected to the land patterns 54B and 52A are connected to the land patterns 53C and 54C instead of the land patterns 54B and 52A. The land patterns 51C to 54C are connected to the terminal electrodes E1C to E4C, respectively. With such a layout, the balanced transmission lines STL1, SBL1 and the balanced transmission lines STL2, STL2 can be formed in parallel and linearly as in the first embodiment.

  Since the substrate 50 is configured as described above, by mounting the surface mount type pulse transformer 30 on the substrate 50, the connection between the terminal electrodes of the surface mount type pulse transformer 30 and the connection of the input / output and the intermediate tap can be performed. 50 can be realized by the wiring pattern on 50.

  As described above, the surface mount pulse transformer 30 functions as a surface mount pulse transformer with a common mode filter in which a common mode filter is added to the output side of the surface mount pulse transformer 20. Then, it is possible to configure a surface mount type pulse transformer with a common mode filter by arranging three common mode filters having the same configuration on the substrate.

  As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to such embodiment at all, and this invention can be implemented in various aspects in the range which does not deviate from the summary. Of course.

  For example, in the first embodiment, as shown in FIG. 2, the two surface mount type common mode filters 10A and 10B are arranged so that the terminal electrodes connected to the intermediate tap face each other. As a result, the input / output terminals are located at both ends of the surface-mount type pulse transformer 20, and the plus-side terminal and the minus-side terminal are separated. For example, as shown in FIG. By changing the direction of, it becomes possible to bring the plus side terminal and the minus side terminal closer to each other.

  In addition to the pulse transformer described in the above embodiment, a balun transformer is also known as a transformer inserted in the signal line. However, it is difficult to apply the present invention to the balun transformer. This will be described in detail below.

  FIG. 9A shows an equivalent circuit of a general pulse transformer, and FIG. 9B shows an equivalent circuit of a general balun transformer. As shown in these figures, both the pulse transformer and the balun transformer have two coils (coils L1 and L2) on the input side and two coils (coils L3 and L4) on the output side. .

Since the pulse transformer is a balanced input / output circuit as described above, the input terminal (plus side input terminal IN + and minus side input terminal IN−) and the output terminal (plus side output terminal OUT + and minus side output terminal OUT−). There are two each. The input current flows in a direction (current i _{in +} and current i _in− ) from the positive input terminal IN + and the negative input terminal IN− toward the input intermediate tap CT (ground), and the coils L1 and L2 are connected. There is no time difference between the flowing currents. The direction in which the output current flows is a direction (current i _{out +} and current i _out− ) from the output-side intermediate tap CT (ground) to each of the plus-side output terminal OUT + and the minus-side output terminal OUT−. There is no time difference between the currents flowing through L4.

On the other hand, since the balun transformer is an unbalanced input balanced output circuit, it has only one input terminal (input terminal IN) and 2 output terminals (plus output terminal OUT + and minus output terminal OUT-). There is one. The other end of coil L2 (the end opposite to the end connected to coil L1) is connected to the ground. The direction in which the input current flows is the direction from the input terminal IN toward the other end of the coil L2 (current i _in ), and the current flowing in the coil L2 is a current that is delayed with respect to the current flowing in the coil L1. The direction in which the output current flows is a direction (current i _out ) from the negative output terminal OUT− to the positive output terminal OUT +, and the current flowing through the coil L3 is delayed with respect to the current flowing through the coil L4. Current.

  Thus, the pulse transformer and the balun transformer differ in that there is a time difference in current between the two coils on the input side and the two coils on the output side. When there is such a time difference, the coil L1 and the coil L4, and the coil L2 and the coil L3 must be magnetically coupled. As described above, in the present invention, since the coils L1 and L4 and the coils L2 and L3 are not magnetically coupled, it is difficult to apply the present invention to a balun transformer.

It is a schematic perspective view which shows the external appearance structure of the surface mount type common mode filter used for preferable embodiment of this invention. 1 is a schematic diagram of a surface mount pulse transformer according to a preferred first embodiment of the present invention. FIG. It is a figure which shows the equivalent circuit of the surface mount-type pulse transformer by preferable 1st Embodiment of this invention. 1 is a plan view of a printed circuit board on which a surface-mount type pulse transformer according to a first preferred embodiment of the present invention is mounted. FIG. 6 is a schematic diagram of a surface mount pulse transformer according to a second preferred embodiment of the present invention. It is a figure which shows the equivalent circuit of the surface mount type pulse transformer by preferable 2nd Embodiment of this invention. It is a top view of the printed circuit board with which the surface mount type pulse transformer by the preferable 2nd Embodiment of this invention is mounted. It is the modification of the schematic diagram of the surface mount-type pulse transformer by preferable 1st Embodiment of this invention. (A) is a figure which shows the equivalent circuit of a general pulse transformer. (B) is a figure which shows the equivalent circuit of a general balun transformer. It is a schematic perspective view which shows the external appearance structure of the surface mount-type pulse transformer by the background art of this invention. It is a figure which shows the equivalent circuit of the surface mount type pulse transformer by the background art of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Surface mount type common mode filter 11 Drum type core 11a Core part 11b, 11c Eaves part 12 Plate core 20 Surface mount type pulse transformer 30 Surface mount type pulse transformer 50 with a common mode filter Printed circuit boards 50A-50C Mounting area 51A- 54A, 51B to 54B, 51C to 54C Land patterns E1 to E4 Terminal electrodes L1 to L4 Coils S1 to S4 Winding

Claims (2)

A first drum core in which the first and third windings are wound in the same winding direction, and a second in which the second and fourth windings are wound in the same winding direction. With a drum-type core
An end of one end of the first drum core of the first winding is connected to a positive input terminal;
The other end of the second drum core of the second winding is connected to the negative input terminal,
An end of the first winding on the other end side of the first drum core and an end of the second winding on the one end side of the second drum core are connected to an input side intermediate tap. ,
An end of one end of the first drum core of the third winding is connected to a plus output terminal;
The other end of the second winding core of the fourth winding is connected to the negative output terminal,
An end of the third winding on the other end side of the first drum-type core and an end of the fourth winding on the one end side of the second drum-type core are connected to an output-side intermediate tap. A surface mount type pulse transformer. A first drum core in which the first and third windings are wound in the same winding direction, and a second in which the second and fourth windings are wound in the same winding direction. And a third drum core in which the fifth and sixth windings are wound in the same winding direction,
An end portion on one end side of the first drum type core of the third winding and an end portion on one end side of the third drum type core of the fifth winding are connected,
An end of the fourth winding on the other end side of the second drum type core and an end of the sixth winding on the one end side of the third drum type core are connected,
An end of one end of the first drum core of the first winding is connected to a positive input terminal;
The other end of the second drum core of the second winding is connected to the negative input terminal,
An end of the first winding on the other end side of the first drum core and an end of the second winding on the one end side of the second drum core are connected to an input side intermediate tap. ,
An end of the third winding on the other end side of the first drum-type core and an end of the fourth winding on the one end side of the second drum-type core are connected to an output-side intermediate tap. ,
The other end of the third drum core of the fifth winding is connected to the plus output terminal,
A surface-mount type pulse transformer with a common mode filter, characterized in that an end portion on the other end side of the third drum core of the sixth winding is connected to a negative output terminal.

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