JP2006216633A - Power supply device and ferrite core used therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power supply device by using MOSFETs as a switching component that can reduce switching noises using a simple constitution. <P>SOLUTION: A single ferrite core 10, provided with three terminal insertion holes 16, 17 and 18 into which the respective terminals 13, 14 and 15 of the gate, the drain and the source of a MOSFET 4 are inserted, is attached to the MOSFET. Each of the terminal insertion holes is bent in the direction of arrow A at its root side and in the direction of arrow B at its tip side, respectively, so as to correct the attitude of the inserted terminals. Thus, the side surface of the terminal insertion hole is brought into contact with the terminal of the MOSFET and a plurality of contact parts 25 and 26, so that the ferrite core can be prevented from dropping out from the MOSFET and the mounting workability of the MOSFET to a circuit board can be improved as a result. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a power supply device including a step-up transformer, a switching element that switches a DC voltage supplied to a primary side of the step-up transformer, and a ferrite core used therefor.

  Conventionally, various measures have been taken in switching elements in order to reduce switching noise. For example, Patent Document 1 shows an FET in which a ferrite core is connected in series between a gate electrode and an external lead terminal, and these are further sealed with a resin package. Patent Document 2 shows a transistor in which a coil is connected to each terminal of an emitter, a collector, and a base, and the outside thereof is sealed with resin. Patent Document 3 discloses a method for manufacturing a ferrite core in which a lead wire is fixed with an adhesive after inserting a bent portion of the lead wire into a through hole of the ferrite core. In Patent Document 4, a coating layer having elasticity and insulation is formed on the surface of the ferrite core, and the ferrite core is prevented from falling off by contact friction between the coating layer and the terminal of the electronic component. A ferrite core is shown.

Patent Document 5 discloses a method for manufacturing a signal line filter with a lead terminal used for a circuit board of a digital device which is an application example of a ferrite core. Patent Document 6 discloses a ferrite core in which a lead wire is locked by a shape memory alloy. Patent Document 7 discloses a method for manufacturing a cylindrical ferrite core. Patent Document 8 discloses a ferrite core having an outer peripheral groove for winding a lead wire.
JP-A-8-70093 JP-A-8-204378 JP 61-42905 A JP 2001-313215 A JP-A 63-198276 JP 59-146913 JP 60-34009 A Japanese Utility Model Publication No. 5-85015

  However, the configurations shown in Patent Document 1 and Patent Document 2 have an excellent effect of reducing switching noise, but on the other hand, the structure of the switching element is complicated and a general-purpose element is used. Therefore, it is not suitable for low-priced consumer electronic devices with increased costs. In addition, the ferrite cores disclosed in Patent Document 3 and Patent Document 4 are difficult to employ in mass-produced electronic devices because the manufacturing process is complicated.

  The present invention has been made in order to solve the above-described problems. A power supply device and a ferrite core used for the power supply device that are capable of reducing costs with a simple configuration while reducing switching noise and improving productivity. The purpose is to provide.

  In order to achieve the above object, the invention of claim 1 has a primary side coil and a secondary side coil, obtains a boost output on the secondary side and supplies power to a load, In a power supply device including a MOSFET for switching a DC voltage supplied to the primary side and a circuit board on which the step-up transformer and the MOSFET are mounted, three rectangular terminals of the MOSFET gate, drain, and source are inserted. The ferrite core further includes a single ferrite core that has a terminal insertion hole and is attached to each rectangular terminal of the MOSFET, and the ferrite core is formed by joining two parts divided by a plane including each terminal insertion hole And at least one of the terminal insertion holes is a normal direction of the wide side surface of the rectangular terminal at the base side when the corresponding rectangular terminal is inserted. 1 is formed in a winding direction so as to bend in the second direction side opposite to the first direction on the tip side, thereby inserting the terminal when the MOSFET is mounted on the circuit board. Since the side surface of the hole comes into contact with the rectangular terminal of the MOSFET at a plurality of locations, the ferrite core is prevented from falling off from the MOSFET, and the mounting workability to the substrate is improved.

  According to a second aspect of the present invention, a ferrite core having a terminal insertion hole into which a terminal of an electronic component is inserted is formed by joining two parts divided by a plane including the terminal insertion hole. When the terminal is inserted, the terminal is bent so as to be bent.

  The invention according to claim 3 has a primary side coil and a secondary side coil, obtains a boost output on the secondary side and supplies power to the load, and is supplied to the primary side of the boost transformer. In a power supply device including a switching element that switches a DC voltage and a circuit board on which the step-up transformer and the switching element are mounted, the ferrite core according to claim 2 is further provided, and when the switching element is mounted on the circuit board, Since the side surface of the terminal insertion hole comes into contact with the terminal of the switching element, the ferrite core is prevented from falling off from the switching element, and the mounting workability to the board is improved.

  According to the first aspect of the present invention, since at least one of the terminal insertion holes is formed to be bent, the rectangular terminal is curved when the corresponding rectangular terminal is inserted. As a result, the side surface of the terminal insertion hole comes into contact with the rectangular terminal at a plurality of locations, so that the ferrite core is prevented from falling off from the MOSFET due to friction between them, and the mounting workability on the board is improved, and the power supply device Productivity when mass-producing is increased. Further, since the terminal insertion hole is formed to bend in the first direction side that is the normal direction of the wide side surface of the rectangular terminal and the second direction side that is opposite to the first direction, The rectangular terminal can be easily bent by simply inserting the terminal into the terminal insertion hole of the ferrite core. As a result, the ferrite core can be easily and smoothly attached to the rectangular terminal of the MOSFET, and an extra burden is not imposed on the operator of the production line of the power supply device. In addition, since the terminal insertion hole is formed to bend in the first direction side and the second direction side, the terminal can be pulled out from the terminal insertion hole in accordance with the direction of the terminal extending from the element body of the MOSFET. it can. As a result, the MOSFET can be mounted on the circuit board in an upright position, and therefore the attitude of the heat sink separately attached to the MOSFET with respect to the circuit board does not need to be changed as before. Further, the joining of the ferrite core configured in two parts can be performed on a line different from the mounting line of the MOSFET to the circuit board, so that it is not necessary to modify the mounting line.

  According to the invention of claim 2, since the terminal insertion hole is formed to be bent, the terminal of the electronic component is inserted while being bent. As a result, the side surface of the terminal insertion hole comes into contact with the terminal of the electronic component at a plurality of locations, so that the ferrite core is prevented from falling off from the electronic component.

  According to the invention of claim 3, the mounting workability of the switching element to the circuit board is improved, and the productivity when mass-producing the power supply device is increased. In addition, since the ferrite core that is divided into two parts can be joined on a line different from the mounting line of the MOSFET to the circuit board, it is not necessary to modify the mounting line.

  A power supply device according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a circuit diagram of the power supply device. The power supply device 1 includes a rectifying / smoothing circuit 2 for obtaining a DC voltage from a commercial AC power supply 5, a step-up transformer 3 that boosts the DC voltage supplied from the rectifying / smoothing circuit 2 and supplies power to a load, and a step-up transformer 3. And a MOSFET (switching element) 4 for switching a direct current supplied to. The rectifying / smoothing circuit 2 includes a bridge rectifying circuit 6 that rectifies a DC voltage supplied from a commercial AC power supply 5, a smoothing capacitor 7 that smoothes the DC voltage rectified by the bridge rectifying circuit 6, and the like. The step-up transformer 3 includes a primary side coil 8 to which a DC voltage is applied from the rectifying and smoothing circuit 2, a secondary side coil 9 that obtains a step-up output and supplies power to a load, and the like. The step-up transformer 3 and the MOSFET 4 are mounted on the circuit board of the power supply device 1.

  2 to 4 show the MOSFET 4 and the ferrite core 10 attached to each terminal of the MOSFET 4. The ferrite core 10 is formed by joining two block-shaped ferrite pieces 11 and 12, and has three terminals through which the gate, drain and source terminals (leads) 13, 14 and 15 of the MOSFET 4 are inserted. Insertion holes 16, 17, 18 are provided. Each of the terminals 13, 14, 15 of the MOSFET 4 is usually formed in a rectangular cross section, and the cross sections of the terminal insertion holes 16, 17, 18 are also formed in a rectangular shape so as to correspond thereto. Further, when inserting the corresponding terminals 13, 14, 15 into the terminal insertion holes 16, 17, 18, the base side of the terminal is the first direction side that is the normal direction of the wide side surface 19 (the front side of the MOSFET 4: In the direction of arrow A), the tip end side is bent so as to bend in the second direction side (the back side of MOSFET 4: arrow B direction side) opposite to the first direction. The ferrite core 10 is divided into two by a plane including the three terminal insertion holes 16, 17 and 18.

  As shown in FIG. 4, the ferrite core 10 is formed by joining the joining surfaces 20 with the ferrite pieces 11, 12 having the same shape turned upside down. Groove portions 21 for forming terminal insertion holes 16, 17, 18 are formed on the joint surfaces 20 of the ferrite pieces 11, 12. The cross section of the groove portion 21 is formed in a rectangular shape corresponding to each of the terminals 13, 14, 15 of the MOSFET 4, and its width dimension W 1 is slightly smaller than the width dimension W 0 of the wide side surface 19 of each terminal 13, 14, 15. It is set to be large. Further, the depth dimension D1 of the groove 21 is gradually larger toward the other end face so that it is slightly larger than the thickness dimension T0 of the MOSFET terminals 13, 14, 15 in the vicinity of one end face of the ferrite pieces 11, 12. It is set to be shallow and to be zero in the vicinity of the other end face. The groove bottom of the groove portion 21 is gently curved so that the tips of the terminals 13, 14, 15 do not interfere when the ferrite core 10 is attached to the terminals 13, 14, 15 of the MOSFET 4. By joining the ferrite pieces 11 and 12 in which such a groove portion 21 is formed, the ferrite core 10 having the terminal insertion holes 16, 17, and 18 that are winding is obtained.

  The ferrite core 10 is attached to the MOSFET 4 immediately before being mounted on the circuit board. The ferrite core 10 is mounted by inserting the terminals 13, 14, 15 of the MOSFET 4 into the terminal insertion holes 16, 17, 18 of the ferrite core 10. At this time, as described above, since the groove bottom of the groove portion 21 is gently bent, the tips of the terminals 13, 14, 15 are smoothly inserted without interfering with the side surfaces of the terminal insertion holes 16, 17, 18. The Then, the terminals 13, 14, and 15 inserted through the terminal insertion holes 16, 17, and 18 are corrected by the terminal insertion holes 16, 17, and 18, and the root side is on the arrow A direction side and the tip side is on the arrow B direction side, respectively. It is curved and is brought into contact with the side surfaces of the terminal insertion holes 16, 17, 18 at a plurality of locations, that is, at the contact portions 25, 26 in FIG. At this time, the side surfaces of the terminals 13, 14, and 15 are pressed against the side surfaces of the terminal insertion holes 16, 17, and 18 to generate a frictional force therebetween, thereby preventing the ferrite core 10 from falling off the MOSFET 4. Will be.

  As described above, according to the power supply device 1 of the present embodiment, since the terminal insertion holes 16, 17, 18 are formed to be bent, they are curved when the corresponding terminals 13, 14, 15 are inserted. . As a result, the side surfaces of the terminal insertion holes 16, 17, 18 come into contact with the terminals 13, 14, 15 at a plurality of contact portions 25, 26, so that the ferrite core 10 is prevented from falling off from the MOSFET 4, The mounting workability on the circuit board is improved, and the productivity when mass-producing the power supply device 1 is increased. Further, since the terminal insertion holes 16, 17, 18 are formed to bend in the direction of arrow A and the direction of arrow B, which is the opposite direction, the terminals 13, 14, 15 are connected to the terminal insertion holes 16 of the ferrite core 10. , 17 and 18, the terminals 13, 14 and 15 are easily bent. Thereby, the mounting operation | work of the ferrite core 10 with respect to MOSFET4 can also be performed easily and smoothly, and the extra burden is not imposed on the operator of the production line of the power supply device 1. FIG. Further, since the terminal insertion holes 16, 17, 18 are formed to bend in the direction of the arrow A and the direction of the arrow B, the terminals are arranged in accordance with the direction of the terminals 13, 14, 15 extending from the element body of the MOSFET 4. The terminals 13, 14, 15 can be drawn out from the insertion holes 16, 17, 18. As a result, the MOSFET 4 can be mounted on the circuit board in an upright position, so that the posture of the heat sink of the MOSFET 4 with respect to the circuit board does not need to be changed as before. Furthermore, since the ferrite pieces 11 and 12 can be joined on a line different from the mounting line of the MOSFET 4 to the circuit board, it is not necessary to modify the mounting line.

  Note that the present invention is not limited to the configuration of the above-described embodiment, and any one of the at least three terminal insertion holes 16, 17, and 18 may be formed to be bent. Further, the terminal insertion hole 17 corresponding to the drain terminal 14 is bent in the direction of the arrow A direction and the arrow B direction in order from the base side to the tip side, and the other gate terminal 13 and the source terminal 15 are set to the arrow B opposite to the above. You may curve to the direction side and the arrow A direction side. In this case, since the drain terminal 14 is deformed into a shape different from that of the other gate terminals 13 and source terminals 15, the ferrite core 10 can be more reliably prevented from falling off.

  The present invention can be modified in various ways. For example, as shown in FIG. 5, a ferrite core 30 in which one terminal insertion hole 33 is formed is attached only to the drain terminal 14 where large switching noise occurs. You may do it. The ferrite core 30 is also divided into two parts by ferrite pieces 31 and 32. Furthermore, the switching element on which the ferrite core 10 or 30 is mounted is not limited to the MOSFET 4 and may be a transistor as well as other FETs.

The circuit diagram of the power unit by one embodiment of the present invention. (A) is a front view of MOSFET and a ferrite core applied to the apparatus, (b) is the side view. The perspective view of the MOSFET and a ferrite core. The assembly perspective view of the MOSFET and ferrite core. The perspective view of the ferrite core different from the MOSFET.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Power supply device 2 Rectification smoothing circuit 3 Step-up transformer 4 MOSFET (switching element)
8 Primary coil 9 Secondary coil 10 Ferrite core 13, 14, 15 Terminal 16, 17, 18 Terminal insertion hole 19 Wide side surface 30 Ferrite core 33 Terminal insertion hole

Claims (3)

A step-up transformer having a primary side coil and a secondary side coil to obtain a step-up output on the secondary side and supplying power to a load; a MOSFET for switching a DC voltage supplied to the primary side of the step-up transformer; In a power supply device comprising a circuit board on which the step-up transformer and the MOSFET are mounted,
The MOSFET has three terminal insertion holes through which the rectangular terminals of the gate, drain and source of the MOSFET are inserted, and further includes a single ferrite core attached to each rectangular terminal of the MOSFET,
The ferrite core is formed by joining two parts divided by a plane including each terminal insertion hole,
When at least one of the terminal insertion holes is inserted into the corresponding rectangular terminal, the terminal is connected to the first direction side which is the normal direction of the wide side surface of the rectangular terminal on the base side and the first side on the distal end side. Are formed so as to bend in a second direction side opposite to the direction of
As a result, when the MOSFET is mounted on the circuit board, the side surface of the terminal insertion hole comes into contact with the rectangular terminal of the MOSFET at a plurality of locations, so that the ferrite core is prevented from falling off from the MOSFET. A power supply device characterized in that mounting workability of the battery is improved. In ferrite cores with terminal insertion holes through which terminals of electronic components are inserted,
Formed by joining two parts divided by a plane including the terminal insertion hole,
The ferrite core characterized in that the terminal insertion hole is formed to be bent so as to bend the terminal when the terminal is inserted. A step-up transformer having a primary side coil and a secondary side coil to obtain a step-up output on the secondary side and supplying power to a load, and a switching element for switching a DC voltage supplied to the primary side of the step-up transformer And a circuit board on which the step-up transformer and the switching element are mounted,
The ferrite core according to claim 2, further comprising:
When the switching element is mounted on the circuit board, the side surface of the terminal insertion hole comes into contact with the terminal of the switching element, so that the ferrite core is prevented from falling off from the switching element, and the mounting workability to the board is improved. Improved power supply device.

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