Switching power supply device

Abstract

A switching power supply device (1000) comprises: a first substrate (100); a second substrate (200); a transformer (20); and a feedback wiring unit (80). A primary circuit (101) that receives power is formed on the first substrate (100). A secondary circuit (201) capable of transmitting power to the outside is formed on the second substrate (200). The second substrate (200) is a separate substrate from the first substrate (100). The secondary circuit (201) includes a feedback circuit (201b) that generates a feedback signal. The feedback signal is transmitted from the secondary circuit (201) to the primary circuit (101) via the feedback wiring unit (80).

Description

Switching Power Supply

[0001] The present invention relates to a switching power supply device.

[0002] A switching power supply is a device that converts power from DC to DC or from AC to DC. A switching power supply may be equipped with a switching transformer and a photocoupler. The switching transformer and photocoupler are insulating components. In a switching power supply, the primary circuit and the secondary circuit are separated via these insulating components. JP 8-130125 A discloses a power supply in which the primary circuit and the secondary circuit are mounted on separate boards and connected by a transformer, from the perspective of ensuring insulation between the primary circuit and the secondary circuit while miniaturizing the entire device.

[0003] Japanese Patent Application Publication No. 8-130125

[0004] However, in the power supply device disclosed in JP-A-8-130125, a feedback signal for monitoring and adjusting the output voltage cannot be exchanged between the primary and secondary circuits, making it difficult to control the output voltage with high precision.

[0005] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a switching power supply device that can achieve both a compact device and high output precision.

[0006] A switching power supply device according to the present disclosure includes a first substrate, a second substrate, a switching transformer, and a feedback wiring section. The first substrate has a primary circuit formed thereon that receives power from an input terminal. The second substrate has a secondary circuit formed thereon that can transmit power from an output terminal to the outside. The switching transformer is interposed between the first substrate and the second substrate and converts power. The second substrate is a substrate separate from the first substrate. The secondary circuit includes a feedback circuit that generates a feedback signal related to the power output from the output terminal. The feedback signal is transmitted from the secondary circuit to the primary circuit via the feedback wiring section.

[0007] According to the present disclosure, the second substrate is a substrate separate from the first substrate and includes a feedback wiring section, thereby providing a switching power supply device that achieves both miniaturization and high output precision.

[0008] 4 is a circuit block diagram of a switching power supply device according to a first embodiment. FIG. 5 is a schematic perspective view of a module included in the switching power supply device according to the first embodiment. FIG. 6 is a schematic view showing an aspect of the second substrate of FIG. 2 as viewed from above in the Z direction. FIG. 7 is a schematic perspective view of the transformer shown in FIG. 2 removed. FIG. 8 is a schematic cross-sectional view of a portion along line V-V of FIG. 4. FIG. 9 is a schematic view showing the configuration of a core of the first embodiment. FIG. 10 is a schematic side view showing a first example of an aspect of FIG. 2 as viewed from the side in the direction indicated by arrow A in the first embodiment. FIG. 11 is a schematic side view showing a second example of an aspect of FIG. 2 as viewed from the side in the direction indicated by arrow A in the first embodiment. FIG. 12 is a schematic side view showing a third example of an aspect of FIG. 2 as viewed from the side in the direction indicated by arrow A in the first embodiment. FIG. 13 is a circuit block diagram of a switching power supply device according to a first comparative example of the first embodiment. FIG. 14 is a schematic perspective view of a module included in the switching power supply device according to the first comparative example of the first embodiment. FIG. 15 is a circuit block diagram of a switching power supply device according to a second comparative example of the first embodiment. FIG. 16 is a schematic perspective view of a module included in the switching power supply device according to the second comparative example of the first embodiment. FIG. 17 is a schematic side view showing a fourth example of an aspect of FIG. 2 as viewed from the side in the direction indicated by arrow A in the first embodiment. 17 is a schematic perspective view of a module included in a switching power supply device according to a second embodiment. 18 is a schematic perspective view of a module included in a switching power supply device according to a second embodiment. 19 is a schematic perspective view of a module included in a switching power supply device according to a third embodiment. 20 is a schematic perspective view of a module included in a switching power supply device according to a fourth embodiment. 21 is a schematic perspective view of a module included in a switching power supply device according to a fourth embodiment. 22 is a schematic perspective view of a module included in a switching power supply device according to a fourth embodiment. 23 is a schematic perspective view of a module included in a switching power supply device according to a fourth embodiment. 24 is a schematic perspective view of a module included in a switching power supply device according to a fourth embodiment. 25 is a schematic perspective view of a module included in a switching power supply device according to a fourth embodiment. 26 is a schematic perspective view of a module included in a switching power supply device according to a fourth embodiment. 27 is a schematic perspective view of a module included in a switching power supply device according to a fourth embodiment. 28 is a schematic perspective view of a module included in a switching power supply device according to a fourth embodiment. 29 is a schematic perspective view of a module included in a switching power supply device according to a fourth embodiment. 30 is a schematic perspective view of a module included in a switching power supply device according to a fourth embodiment.25. FIG. 26 is a schematic plan view of the transformer of embodiment 4 obtained through the process of FIG. 25. FIG. 27 is a schematic cross-sectional view of the substrate of FIG. 26. FIG. 28 is a schematic cross-sectional view showing an aspect in which a core is attached to the substrate of FIG. 27. FIG. 29 is a schematic plan view of a substrate of the transformer substrate of FIGS. 27 and 28 on which a first winding and feedback wiring are formed. FIG. 29 is a schematic plan view of a substrate of the transformer substrate of FIGS. 27 and 28 on which a second winding, third winding, or fourth winding is formed. FIG. 29 is a schematic plan view of a first modified example of a transformer substrate on which feedback wiring is formed. FIG. 30 is a schematic enlarged view of a portion where the transformer of embodiment 4 is connected to the first substrate and the second substrate. FIG. 31 is a schematic plan view of a transformer as a comparative example of embodiment 4.

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. For convenience of explanation, the X, Y, and Z directions are defined.

[0010] Embodiment 1. <Basic Configuration> Fig. 1 is a circuit block diagram of a switching power supply device according to embodiment 1. As shown in Fig. 1, a power supply device 1000 serving as a switching power supply device according to this embodiment converts power received from an external source and transmits the converted power to the outside. The power supply device 1000 mainly includes an input terminal IN, a module 300, and an output terminal OUT. The module 300 mainly includes a first substrate 100, a transformer 20, a second substrate 200, and a feedback wiring section 80. As shown in Fig. 1, in the power supply device 1000, the input terminal IN, the module 300, and the output terminal OUT are arranged in this order from the power input side to the power output side. In the module 300, the first substrate 100, the transformer 20, and the second substrate 200 are arranged in this order from the power input side to the power output side.

[0011] The input terminal IN receives power from outside the power supply device 1000. The power received by the input terminal IN is AC or DC. The output terminal OUT transmits power to outside the power supply device 1000. The power transmitted by the output terminal OUT to outside the power supply device 1000 is DC.

[0012] The module 300 is a switching power supply module. A primary circuit 101 is formed on the first substrate 100. The primary circuit 101 receives power from an input terminal IN. The primary circuit 101 includes a switching circuit 101a and a control circuit 101b. The switching circuit 101a receives power from the input terminal IN. The control circuit 101b controls the switching circuit 101a.

[0013] The second substrate 200 has a secondary circuit 201 formed thereon. The secondary circuit 201 transmits power to the output terminal OUT so that power can be transmitted from the output terminal OUT to the outside. The secondary circuit 201 includes a rectifier circuit 201a and a feedback circuit 201b. The rectifier circuit 201a is connected to the output terminal OUT. The magnitude relationship between the voltages applied to the primary circuit 101 and the secondary circuit 201 is arbitrary.

[0014] The feedback circuit 201b is connected to the output terminal OUT and the control circuit 101b. The feedback circuit 201b generates a feedback signal related to the power output from the output terminal OUT. The feedback signal can be any signal indicating the characteristics (e.g., voltage) of the DC to be output from the output terminal OUT. The feedback signal is transmitted from the feedback circuit 201b to the input terminal IN. As a result, the feedback signal is input to the control circuit 101b connected to the feedback circuit 201b. In this way, a feedback signal indicating the characteristics of the output power is transmitted from the secondary circuit 201 side to the control circuit 101b on the primary circuit 101 side. The control circuit 101b controls the switching circuit 101a based on the feedback signal. In this way, feedback control is performed in the module 300.

[0015] The feedback wiring section 80 is a path for transmitting a feedback signal from the feedback circuit 201b to the control circuit 101b. In other words, the feedback signal output from the feedback circuit 201b is input to the control circuit 101b. The feedback signal is transmitted from the secondary circuit 201 to the primary circuit 101 via the feedback wiring section 80.

[0016] FIG. 2 is a schematic perspective view of a module included in the switching power supply device according to the first embodiment. Note that some elements are omitted from FIG. 2 . Other figures similar to FIG. 2 also omit some elements. As shown in FIG. 2 , in module 300, first substrate 100 is a substrate separate from second substrate 200. For example, as shown in FIG. 2 , first substrate 100 and second substrate 200 are disposed spaced apart from each other in the Z direction. In a plan view from the Z direction, first substrate 100 and second substrate 200 may overlap. The Z direction corresponds to the height direction, or vertical direction. The planar shapes of the main surfaces of first substrate 100 and second substrate 200 are, for example, rectangular. The following description is based on the assumption that first substrate 100 is disposed on the lower side in the Z direction and second substrate 200 is disposed on the upper side in the Z direction. However, first substrate 100 may be disposed on the upper side in the Z direction and second substrate 200 on the lower side.

[0017] As shown in FIGS. 1 and 2 , the transformer 20 is a so-called switching transformer. The transformer 20 is interposed between the first substrate 100 and the second substrate 200. In other words, the first substrate 100 and the second substrate 200 are disposed so as to face each other with the transformer 20 sandwiched therebetween. The transformer 20 includes a winding N. The winding N has a first winding N1, a second winding N2, and a third winding N3. These windings N are wound in the circumferential direction indicated by the arrow R in FIG. 2 . The winding N, which is formed by gathering together wire wound many times in the circumferential direction, has, for example, a cylindrical shape, and the height direction of the cylindrical shape (the direction in which the central axis extends) is aligned with the Z direction. Therefore, in FIG. 2 , the winding N is oriented upright, extending vertically.

[0018] The first winding N1 is connected to the switching circuit 101a. The second winding N2 is connected to the rectifier circuit 201a. The third winding N3 is connected to the control circuit 101b. The current flowing from the switching circuit 101a to the first winding N1 is high-frequency pulsed AC. The current flowing from the second winding N2 to the rectifier circuit 201a is AC. The transformer 20 of the power supply device 1000 functions as an insulating component and also performs AC power conversion. The transformer 20 electrically isolates the input terminal IN from the output terminal OUT. This improves the safety of the power supply device 1000 compared to, for example, a non-isolated power supply device.

[0019] The feedback wiring section 80 includes a photocoupler 81 and a feedback wiring 82. The photocoupler 81 is disposed on the main surface of the second substrate 200. However, the photocoupler 81 may also be disposed on the first substrate 100. The photocoupler 81 is a device that converts an electrical signal into an optical signal and transmits it to a light-receiving element, thereby transmitting the electrical signal in an electrically isolated state. The feedback wiring 82 is disposed on the transformer 20 and interposed between the first substrate 100 and the second substrate 200. The feedback wiring 82 is electrically connected to the first substrate 100 and the second substrate 200. The feedback wiring 82 includes a wire material primarily composed of aluminum or copper. As shown in FIG. 1 , the feedback wiring 82 connects the feedback circuit 201b of the second substrate 200 and the control circuit 101b of the first substrate 100.

[0020] Fig. 3 is a schematic diagram showing the second substrate of Fig. 2 as viewed from above in the Z direction. As shown in Figs. 2 and 3, a pattern gap AA is provided around the photocoupler 81. The pattern gap AA is an insulating region between the photocoupler 81 and other components, and is provided so that the photocoupler 81 can transmit a feedback signal between the first substrate 100 and the second substrate 200. The planar shape of the pattern gap AA may be a part of a circle or a part of an ellipse.

[0021] Fig. 4 is a schematic perspective view of the transformer shown in Fig. 2. Fig. 5 is a schematic cross-sectional view of a portion taken along line V-V in Fig. 4. Fig. 5 particularly shows the shaded area in Fig. 4. As shown in Figs. 1, 2, 4, and 5, the transformer 20 includes a core 21, a first pin 24a, a second pin 24b, a bobbin 25, and a winding N.

[0022] The bobbin 25 is a component onto which the winding N is directly wound. The bobbin 25 may be formed of a commonly known insulating material such as resin. The bobbin 25 has a bobbin core 25C and bobbin end portions 25D. The bobbin core 25C is located adjacent to the center of the bobbin 25 in a plan view from the Z direction. The bobbin core 25C has a cylindrical shape extending along the Z direction. The winding N is wound around the bobbin core 25C. Therefore, the winding N has a cylindrical shape extending along the Z direction. A wall surface S1 is formed at the centermost side of the bobbin core 25C in a plan view. The inside of the wall surface S1 is hollow. The bobbin end portions 25D are formed at one and the other ends in the Z direction of the cylindrical bobbin core 25C. The pair of bobbin end portions 25D extend along the XY plane. The planar shape of the bobbin end portion 25D as viewed from the Z direction is, for example, circular, although the planar shape may also be square.

[0023] In the transformer 20 of this embodiment, the core 21 is disposed inside the bobbin core portion 25C and around the bobbin 25. The core 21 is a component around which the winding N is wound and which serves as a core through which the magnetic flux generated by the first winding N1 passes. For this reason, the core 21 is preferably formed of a commonly known magnetic material such as ferrite. As shown in FIGS. 2, 4, and 5, the core 21 is composed of two components: a first core 21A and a second core 21B. Here, the first core 21A is disposed below the second core 21B in the Z direction.

[0024] Fig. 6 is a schematic diagram showing the configuration of the core according to embodiment 1. As shown in Fig. 6 and Fig. 5, each of the first core 21A and the second core 21B has a core core portion 21C, a core outer portion 21D, and a core end portion 21E.

[0025] The core core portion 21C, which serves as a core portion, is disposed at the center and a position adjacent to the center when the core 21 is installed in the transformer 20 as shown in FIG. 5 and viewed from above in the Z direction. The core core portion 21C extends along the Z direction when installed in the transformer 20. For example, if the bobbin core portion 25C is cylindrical, the core core portion 21C will be cylindrical. The core outer portion 21D, which serves as an outer portion, is connected to the core core portion 21C by the core end portion 21E. The core outer portion 21D is disposed as a pair, spaced apart from the core core portion 21C in the direction along the XY plane. The core end portion 21E is disposed at the end of the core 21 in the Z direction when installed in the transformer 20. The core end portion 21E of the first core 21A is disposed at the bottom of the first core 21A in the Z direction. The core end portion 21E of the second core 21B is disposed at the top of the second core 21B in the Z direction. The core end portions 21E extend along the XY plane. The planar shape of the core end portion 21E may be rectangular or circular, or may be any other shape.

[0026] As an example, in both (a) and (b) of Figures 6, the first core 21A and the second core 21B have the same shape. In the first core 21A and the second core 21B, the core core portion 21C is cylindrical. When installed in the transformer 20, a pair of core outer portions 21D are arranged with a gap in the Y direction. The core end portion 21E intersects, for example, is perpendicular to, both the core core portion 21C and the core outer portion 21D. However, in the core shown in (a) of Figure 6, the aspect ratio of the dimensions of the core end portion 21E when viewed in plan is smaller than that of the core shown in (b) of Figure 6. Furthermore, in the core shown in (b) of Figure 6, the core end portion 21E is rectangular when viewed in plan from the Z direction. In contrast, in the core shown in (a) of Figure 6, the core end portion 21E has a shape with a portion missing from the rectangular shape when viewed in plan. Either of the cores shown in (a) and (b) of Figure 6 may be used in the transformer 20 of this embodiment.

[0027] The pair of outer core portions 21D are disposed, for example, on the outer side of the core end portion 21E in the Y direction. The outer peripheral surface of each outer core portion 21D, i.e., the surface opposite the core core portion 21C, is rectangular in plan view, for example. The inner peripheral surface of each outer core portion 21D, i.e., the surface facing the core core portion 21C, may have an arc-shaped cross section as shown in FIG. 6 . That is, the inner peripheral surface of each outer core portion 21D may be an outwardly convex curved surface. As a result, when the bobbin 25 has a circular planar shape as viewed in the Z direction, the inner peripheral surface of each outer core portion 21D engages with the circular outer peripheral surface of the bobbin 25.

[0028] As shown by arrow C' in Fig. 2, the first core 21A is placed from the lower side in the Z direction of the bobbin 25. At this time, as shown in Fig. 5, the core core portion 21C of the first core 21A is inserted into the cavity inside the wall surface S1 of the bobbin core portion 25C. As a result, the bobbin 25 is placed so that the bobbin end portion 25D at the bottom is in contact with the core end portion 21E of the first core 21A.

[0029] Similarly, as shown by arrow C in Fig. 2 , the second core 21B is installed from above the bobbin 25 in the Z direction. At this time, as shown in Fig. 5 , the core core portion 21C of the second core 21B is inserted into the cavity inside the wall surface S1. As a result, the bobbin 25 is installed so that the bobbin end portion 25D at the top of the bobbin 25 contacts the core end portion 21E of the second core 21B. The core outer portions 21D of the first core 21A and the second core 21B are arranged outside the outer edge of the bobbin 25 when viewed from above in the Z direction. It is also preferable that the top of the first core 21A and the bottom of the second core 21B are in contact with each other with almost no gap between them, and that they are arranged to form a single core 21.

[0030] As described above, the first core 21A and the second core 21B are placed on the bobbin 25. In this state, the winding N is wound around the bobbin core 25C. More specifically, the winding N is wound around both the bobbin core 25C and the core core 21C. This is because the core core 21C is inserted into the cavity formed by the bobbin core 25C. In other words, the winding N is a conducting wire wound many times around both the bobbin 25 and the core 21C.

[0031] As shown in Fig. 5, the winding N includes a first winding N1, a second winding N2, a third winding N3, and a shield winding N4. The third winding N3 is a bias winding that contributes to the supply of power to the control circuit 101b. In contrast, the shield winding N4 prevents noise within the transformer 20 shown in Fig. 2 from being transmitted to the outside of the transformer 20.

[0032] As shown in FIG. 5 , the first winding N1, second winding N2, third winding N3, and shield winding N4 are wound around the bobbin 25 at intervals in the radial direction, i.e., along the XY plane. In FIG. 5 , the first winding N1, second winding N2, third winding N3, and shield winding N4 are wound in this order from the inside, i.e., the bobbin core 25C side, to the outside. However, the winding order of these windings is not important. Also, in FIG. 5 , the first winding N1 and shield winding N4 are each wound in a single layer in the radial direction, while the second winding N2 and third winding N3 are each wound in two layers. However, this is not a limitation, and the number of layers of each winding is optional. For example, all of the windings N1 to N4 may be wound in one layer or two layers. Alternatively, only the first winding N1 may be wound in two layers, while the others are wound in one layer. Furthermore, only the first winding N1 is wound more times in the height direction, i.e., in the Z direction, than the other windings N2 to N4, and is therefore longer in the Z direction in FIG. 5. The Z direction dimension of each winding is also arbitrary. For example, only the second winding N2 or only the third winding N3 may be longer in the Z direction in FIG. 5 than the others. Alternatively, the Z direction dimensions of all of the windings N1 to N4 may be the same.

[0033] In FIG. 5 , insulating tape 23A is arranged between each winding N to prevent short circuits between the windings. That is, insulating tape 23A is arranged between the first winding N1 and the second winding N2, between the second winding N2 and the third winding N3, and between the third winding N3 and the shield winding N4. Insulating tape 23A is also arranged on the outside of the shield winding N4. The insulating tape 23A on the outside of the shield winding N4 is in contact with the shield winding N4 and faces the core outer portion 21D. Between adjacent insulating tapes 23A, barrier tape 23B is arranged to fill the gap between the winding N and the bobbin end 25D. With the configuration of FIG. 5 , both the insulating tape 23A and the barrier tape 23B are wound around both the bobbin core portion 25C and the core core portion 21C in the radial direction. The insulating tape 23A and the barrier tape 23B may be made of different materials or the same material. Both the insulating tape 23A and the barrier tape 23B are preferably made of a commonly known insulating material such as a resin.

[0034] Other features of the module 300 include the following: As shown in FIG. 2 , each of the first substrate 100 and the second substrate 200 has a through-hole h formed therein, penetrating from one main surface to the other main surface on the opposite side. The first pin 24a of the transformer 20 is inserted into and passes through the through-hole h of the first substrate 100. The first pin 24a is an elongated member formed of a conductive material. The first pin 24a is electrically and mechanically connected to the first substrate 100 via the through-hole h by solder (not shown). Similarly, the second pin 24b of the transformer 20 is inserted into and passes through the through-hole h of the second substrate 200. The second pin 24b is made of the same material as the first pin 24a. The second pin 24b is electrically and mechanically connected to the second substrate 200 via the through-hole h by solder (not shown).

[0035] The first pin 24a, which passes through the through-hole h of the first substrate 100, is electrically connected to the first winding N1 or the third winding N3, which is part of the winding N of the transformer 20. Specifically, as shown in FIG. 2, the first winding N1 or the third winding N3 is wound around the first pin 24a. More specifically, the end of the first winding N1 or the third winding N3, which is wound circumferentially into a cylindrical shape, is pulled out and wound around and connected to the first pin 24a. Although not shown in FIG. 2, the second winding N2 is wound around the second pin 24b. As a result, the winding N of the transformer 20 is connected to the switching circuit 101a or the control circuit 101b of the primary circuit 101, as shown in FIG. 1. Although not shown in FIG. 2, the second winding N2 is connected to the rectifier circuit 201a of the secondary circuit 201.

[0036] The first pin 24a and the second pin 24b are arranged to protrude from a part of the body of the bobbin 25. Here, Fig. 7 is a schematic side view showing a first example of a side view of Fig. 2 in the first embodiment, viewed from the direction indicated by arrow A. In other words, Fig. 7 shows a side view of Fig. 2 viewed from the negative side in the X direction. As shown in Fig. 7, a feedback wiring 82, which is hidden and not visible in Fig. 2, is arranged on the left side surface of Fig. 2.

[0037] The bobbin 25 has a pair of pin penetration portions 25E at each of the top and bottom in the Z direction. The first pin 24a and the second pin 24b penetrate the pin penetration portions 25E to extend in the Z direction. Therefore, through holes are formed in the pin penetration portions 25E. The pin penetration portions 25E generally correspond to the visible portions at the top and bottom ends of the transformer 20 shown in FIGS. 2 and 4 at both ends in the X direction. The pair of pin penetration portions 25E on the upper Z side in FIGS. 2 and 4 both protrude above the bobbin end 25D (see FIG. 5) on the upper Z side. One of the pin penetration portions 25E protrudes leftward beyond the left end in the X direction of the upper Z-direction bobbin end 25D. The other of the pin penetration portions 25E protrudes rightward beyond the right end in the X direction of the upper Z-direction bobbin end 25D. 2 and 4, each of the pair of pin penetration portions 25E on the lower side in the Z direction protrudes below the lower bobbin end 25D (see FIG. 5). One of the pin penetration portions 25E protrudes leftward beyond the left end in the X direction of the lower bobbin end 25D in the Z direction. The other pin penetration portion 25E protrudes rightward beyond the right end in the X direction of the lower bobbin end 25D in the Z direction.

[0038] A standoff 25F is formed in the pin penetration portion 25E on the upper side in the Z direction. The standoff 25F protrudes further upward from the pin penetration portion 25E. The standoff 25F extends upward from one and other ends of the pin penetration portion 25E in the Y direction. The standoff 25F is bonded to the lower main surface of the second substrate 200. As a result, a gap is formed in the Z direction between the pin penetration portion 25E and the second substrate 200. Similarly, a standoff 25F is formed in the pin penetration portion 25E on the lower side in the Z direction. The standoff 25F protrudes further downward from the pin penetration portion 25E. The standoff 25F extends downward from one and other ends of the pin penetration portion 25E in the Y direction. The standoff 25F is bonded to the upper main surface of the first substrate 100. As a result, a gap is formed in the Z direction between the pin penetration portion 25E and the first substrate 100.

[0039] 7, the pair of standoffs 25F on the upper side in the Z direction preferably has a larger dimension in the Z direction than the pair of standoffs 25F on the lower side in the Z direction. As a result, the distance in the Z direction between the second substrate 200 and the pin penetration portion 25E is larger than the distance in the Z direction between the first substrate 100 and the pin penetration portion 25E. This allows the distance between the second substrate 200 on the output terminal OUT side and the core 21 to be larger than the distance between the first substrate 100 on the input terminal IN side and the core 21. This more reliably ensures insulation between the second substrate 200 and the core 21 on the output side.

[0040] It is preferable to set the dimension of the standoff 25F in the Z direction to a constant value. In this way, when manufacturing a plurality of power supply devices 1000, the distance in the Z direction between the first substrate 100 and the second substrate 200 in each power supply device 1000 can be set to a constant value. This makes it possible to suppress manufacturing variations in the power supply devices 1000. This also makes it easier to design components connected to the power supply device 1000. Furthermore, by adjusting the dimension of the standoff 25F in the Z direction, the insulation distance between the first substrate 100 and the second substrate 200 can be easily controlled.

[0041] The feedback wiring 82 includes two wires, a first wiring 82a and a second wiring 82b. The first wiring 82a and the second wiring 82b are electrically connected to the output terminal of the photocoupler 81. Specifically, the first wiring 82a and the second wiring 82b are electrically connected to the light-receiving element (phototransistor) of the photocoupler 81. When the photocoupler 81 transmits a feedback signal from the feedback circuit 201b, currents flow in opposite directions through the first wiring 82a and the second wiring 82b. The second wiring 82b is arranged along the first wiring 82a. Both the first wiring 82a and the second wiring 82b are spaced apart from the outer peripheral surface of the winding N in the X direction and are arranged on the negative side of the winding N in the X direction. Both the first wiring 82a and the second wiring 82b extend along the Z direction.

[0042] 7, similarly to FIG. 2, the winding N is wound in the circumferential direction indicated by the arrow R. The direction along the Z direction, which is the extension direction of the first wiring 82a and the second wiring 82b constituting the feedback wiring 82, intersects with the circumferential direction, which is the extension direction of the winding N. It is preferable that the extension direction of the first wiring 82a and the second wiring 82b be perpendicular to the extension direction of the winding N.

[0043] 7, for the sake of explanation, two first pins 24a1 and 24a2 are extracted from the first pin 24a. Two second pins 24b1 and 24b2 are extracted from the second pin 24b. The second pin 24b1 is disposed directly above the first pin 24a1. The second pin 24b2 is disposed directly above the first pin 24a2. The first wiring 82a is wound around each of the first pin 24a1 and the second pin 24b1. The second wiring 82b is wound around each of the first pin 24a2 and the second pin 24b2. The first wiring 82a and the second wiring 82b electrically connect the first substrate 100 and the second substrate 200 without contacting each other.

[0044] In this embodiment, the feedback wiring 82 extends in the Z direction along the outer circumferential surface of the cylindrical shape formed by the winding N. The outer circumferential surface of the cylindrical winding N, formed by gathering together wire wound in the circumferential direction indicated by the arrow R in FIG. 2, extends in the Z direction. The first substrate 100 and the second substrate 200 face each other in the Z direction, sandwiching the transformer 20 therebetween. In this way, the feedback wiring 82 extends to connect the first substrate 100 and the second substrate 200. Therefore, a path can be formed that can transmit a feedback signal from the second substrate 200 to the first substrate 100.

[0045] <Modifications> Fig. 8 is a schematic side view showing a second example of a configuration in which Fig. 2 in embodiment 1 is viewed from the side in the direction indicated by arrow A. As shown in Fig. 8, the second example has a configuration basically similar to that of the first example, and therefore the same components as those in the first example are given the same reference numerals, and unless there are particular changes, their description will not be repeated. As shown in Fig. 8, first wiring 82a and second wiring 82b may be twisted wires that intersect at an intersection 82c.

[0046] To achieve this, for example, the first wire 82a is wound around each of the first pin 24a1 and the second pin 24b2, and the second wire 82b is wound around each of the first pin 24a2 and the second pin 24b1.

[0047] In FIG. 8 , similar to FIG. 7 , the second pin 24b1 is disposed directly above the first pin 24a1. Also, in FIG. 8 , similar to FIG. 7 , the second pin 24b2 is disposed directly above the first pin 24a2. In FIG. 8 , the first connection portion where the first wiring 82a is electrically connected to the first substrate 100 is the first pin 24a1. The second connection portion where the first wiring 82a is electrically connected to the second substrate 200 is the second pin 24b2. Therefore, the first wiring 82a is disposed at a position other than a position where the first pin 24a1, which is the first connection portion, and the second pin 24b2, which is the second connection portion, overlap each other in a plan view. In this manner, the first wiring 82a is connected to the first pin 24a1 and the second pin 24b2.

[0048] 8 , the first connection portion where second wiring 82b is electrically connected to first substrate 100 is first pin 24a2. The second connection portion where second wiring 82b is electrically connected to second substrate 200 is second pin 24b1. Therefore, second wiring 82b is arranged at a position other than a position where first pin 24a2, which is the first connection portion, and second pin 24b1, which is the second connection portion, overlap each other in a plan view. In this manner, second wiring 82b is connected to first pin 24a2 and second pin 24b1.

[0049] In other words, the first wiring 82a of Fig. 8 is different from the first wiring 82a of Fig. 7 in that the connected second pin 24b is swapped from the second pin 24b1 to the second pin 24b2. The second wiring 82b of Fig. 8 is different from the second wiring 82b of Fig. 7 in that the connected second pin 24b is swapped from the second pin 24b2 to the second pin 24b1. Alternatively, the first wiring 82a of Fig. 8 may be different from the first wiring 82a of Fig. 7 in that the connected first pin 24a is swapped from the first pin 24a1 to the first pin 24a2, while the connected second pin 24b remains the second pin 24b1. The second wiring 82b of Fig. 8 may be different from the second wiring 82b of Fig. 7 in that the connected first pin 24a is swapped from the first pin 24a2 to the first pin 24a1, while the connected second pin 24b remains the second pin 24b2.

[0050] As described above, the connection of the feedback wiring 82 to the pins in FIG. 8 differs from that in FIG. 7 . The feedback wiring 82 in FIG. 7 is connected to the second pin 24b, which is located almost directly below the first pin 24a to which it is connected. That is, in FIG. 7 , the first pin 24a and the second pin 24b connected to the feedback wiring 82 are located at approximately the same position in a plan view from the Z direction. In contrast, in FIG. 8 , either the first pin 24a or the second pin 24b around which the first wiring 82a and the second wiring 82b are wound is swapped. As a result, a single intersection 82c is formed in FIG. 8 . At the intersection 82c, the first wiring 82a and the second wiring 82b may be in contact with each other while maintaining electrical insulation. For example, the first wiring 82a and the second wiring 82b may each include a conductor wire and an insulating coating formed on the surface of the conductor wire.

[0051] 9 is a schematic side view showing a third example of a configuration in which FIG. 2 according to the first embodiment is viewed from the direction indicated by arrow A. As shown in FIG. 9, the first wiring 82a and the second wiring 82b may be twisted wires that intersect at a plurality of intersections 82c. As shown in FIGS. 8 and 9, in this embodiment, the first wiring 82a and the second wiring 82b may be twisted wires that intersect at at least one location.

[0052] <Comparative Example> Fig. 10 is a circuit block diagram of a switching power supply device according to a first comparative example of embodiment 1. Fig. 11 is a schematic perspective view of a module included in a switching power supply device according to a first comparative example of embodiment 1. As shown in Figs. 10 and 11, the first comparative example basically has the same configuration as in Figs. 1 and 2, and therefore the same components as in Figs. 1 and 2 are given the same reference numerals, and description thereof will not be repeated unless there are particular changes.

[0053] 10 and 11 , in the first comparative example, a module 300 includes a transformer 20 and a substrate 120. The substrate 120 has a primary circuit installation section 10 and a secondary circuit installation section 12. A primary circuit 101 having a switching circuit 101a and a control circuit 101b is formed in the primary circuit installation section 10. A secondary circuit 201 having a rectifier circuit 201a and a feedback circuit 201b is formed in the secondary circuit installation section 12.

[0054] Fig. 12 is a circuit block diagram of a switching power supply device according to a second comparative example of embodiment 1. Fig. 13 is a schematic perspective view of a module included in the switching power supply device according to the second comparative example of embodiment 1. As shown in Figs. 12 and 13, the second comparative example basically has the same configuration as Figs. 1 and 2, and therefore the same components as those in Figs. 1 and 2 are designated by the same reference numerals, and description thereof will not be repeated unless there are particular changes.

[0055] 12 and 13, the second comparative example does not have feedback circuit 201b and feedback wiring section 80. The effects of power supply device 1000 according to the present embodiment will be described below by comparing the above-described first and second comparative examples with this embodiment.

[0056] <Operation and Effect> The power supply device 1000 according to this embodiment includes a first substrate 100, a second substrate 200, a transformer 20, and a feedback wiring section 80. The first substrate 100 has a primary circuit 101 formed thereon that receives power from an input terminal IN. The second substrate 200 has a secondary circuit 201 formed thereon that can transmit power to the outside from an output terminal OUT. The transformer 20 is interposed between the first substrate 100 and the second substrate 200 and converts power. The second substrate 200 is a substrate separate from the first substrate 100. The secondary circuit 201 includes a feedback circuit 201b that generates a feedback signal related to the power output from the output terminal OUT. The feedback signal is transmitted from the secondary circuit 201 to the primary circuit 101 via the feedback wiring section 80.

[0057] For example, in the first comparative example shown in FIGS. 10 and 11 , both the primary circuit installation section 10 and the secondary circuit installation section 12 are installed on a single substrate 120. In the first comparative example, a wiring pattern gap BB must be provided on the substrate 120 between the primary circuit installation section 10 and the secondary circuit installation section 12. The wiring pattern gap BB is insulating and has a constant width in the X direction in FIG. 11 . This prevents short circuits between the wiring on the primary circuit installation section 10 and the wiring on the secondary circuit installation section 12. In other words, the primary circuit installation section 10, the secondary circuit installation section 12, and the wiring pattern gap BB must all be provided on the main surface of the single substrate 120. This results in a problem of the main surface of the substrate 120 becoming larger.

[0058] However, in this embodiment, the second substrate 200 is a separate substrate from the first substrate 100. Therefore, the physical distance between the first substrate 100 and the second substrate 200 can be set arbitrarily depending on the operating voltages of the primary circuit 101 and the secondary circuit 201. This allows for a sufficient insulation distance to be provided between the first substrate 100 and the second substrate 200. As a result, for example, the first substrate 100 and the second substrate 200 can be stacked facing each other with a gap in the Z direction, which is the height direction. This allows for higher-density packaging than the first comparative example. Furthermore, only the primary circuit 101 or the secondary circuit 201 needs to be formed on one substrate. Therefore, the first substrate 100 and the second substrate 200 can be made smaller than the substrate 120 in FIG. 11 . Therefore, according to this embodiment, the power supply device 1000 including the module 300 can be made smaller.

[0059] 12 and 13 does not have the feedback circuit 201b and the feedback wiring section 80. This poses a problem in that it is difficult to maintain the output voltage or current at the output terminal OUT at an arbitrary constant value.

[0060] However, in this embodiment, the secondary circuit 201 includes a feedback circuit 201b. A feedback signal generated by the feedback circuit 201b is transmitted from the secondary circuit 201 to the primary circuit 101 via the feedback wiring section 80. In the primary circuit 101, control can be performed based on the feedback signal to maintain the output voltage and other values ​​at a constant value. This makes it possible to maintain the output voltage or current at the output terminal OUT at an arbitrary constant value. This allows for high accuracy in the output voltage at the output terminal OUT.

[0061] In summary, according to this embodiment, it is possible to achieve both a compact power supply device 1000 and high accuracy in output.

[0062] In the power supply device 1000 of this embodiment, the primary circuit 101 includes a switching circuit 101a and a control circuit 101b. The switching circuit 101a receives power from an input terminal IN. The control circuit 101b controls the switching circuit 101a and receives a feedback signal output from a feedback circuit 201b. The secondary circuit 201 includes a rectifier circuit 201a connected to an output terminal OUT. The feedback wiring section 80 includes a photocoupler 81. Such a configuration may be used.

[0063] The primary circuit 101 includes a control circuit 101b, and the feedback wiring unit 80 includes a photocoupler 81. Therefore, a feedback signal for monitoring and adjusting the output voltage of the secondary circuit 201 can be transmitted to the control circuit 101b via the photocoupler 81. This makes it possible to achieve high accuracy of the output voltage at the output terminal OUT, variability of the output voltage, and improvement in output voltage responsiveness to power fluctuations. This effect can be obtained even if the first substrate 100 and the second substrate 200 are independent.

[0064] In the power supply device 1000 of this embodiment, the feedback wiring section 80 may include a feedback wiring 82 installed on the transformer 20. That is, as shown in FIGS. 7 to 9 , the feedback wiring 82 is wound and connected to the first pin 24a and the second pin 24b of the transformer 20. In this manner, the feedback wiring 82 can be electrically connected to the first substrate 100 and the second substrate 200 at the same time as the winding N wound around the bobbin 25. This is because, if a soldering process is used, the feedback wiring 82 can be connected at the same time as the winding N. Therefore, the feedback wiring 82 can be installed without a separate manufacturing process for installing the feedback wiring 82 after manufacturing the transformer 20. This simplifies the manufacturing process.

[0065] In the power supply device 1000 of this embodiment, the transformer 20 includes a core 21 and a winding N wound around the core 21. The direction along the Z direction, which is the extension direction of the feedback wiring 82, intersects with the direction indicated by the arrow R, which is the extension direction of the winding N. In this way, crosstalk noise occurring between the winding N and the feedback wiring 82 can be suppressed.

[0066] In the power supply device 1000 of this embodiment, the feedback wiring 82 preferably includes a wire material whose main component is aluminum or copper. This mechanically connects the first substrate 100 and the second substrate 200 to the feedback wiring 82 whose main component is aluminum or copper. Therefore, heat generated by the first substrate 100 and the second substrate 200 is transferred to the feedback wiring 82. This makes it possible to suppress the temperature difference between the first substrate 100 and the second substrate 200.

[0067] In the power supply device 1000 of this embodiment, the feedback wiring 82 includes a first wiring 82a and a second wiring 82b arranged along the first wiring 82a. The first wiring 82a and the second wiring 82b are twisted wires that intersect at least one location. The intersecting portion is called an intersection 82c. Even with this configuration, a feedback signal can be transmitted from the second substrate 200 to the control circuit 101b on the first substrate 100.

[0068] In the above, the first wiring 82a is connected so that the first connection portion and the second connection portion are disposed at positions other than those where they overlap in a plan view. At the first connection portion, the first wiring 82a is electrically connected to the first substrate 100. At the second connection portion, the first wiring 82a is electrically connected to the second substrate 200. In other words, when FIG. 8 is viewed in a plan view from the Z direction, the first connection portion and the second connection portion of the first wiring 82a do not overlap with each other. In the first wiring 82a, at least one of the X coordinate and the Y coordinate of the first connection portion and the second connection portion differ from each other.

[0069] In the above, the second wiring 82b is connected so that the first connection portion and the second connection portion are positioned at a position other than a position where they overlap in a plan view. At the first connection portion, the second wiring 82b is electrically connected to the first substrate 100. At the second connection portion, the second wiring 82b is electrically connected to the second substrate 200. In other words, when FIG. 8 is viewed in a plan view from the Z direction, the first connection portion and the second connection portion of the second wiring 82b do not overlap with each other. In the second wiring 82b, at least one of the X coordinate and the Y coordinate of the first connection portion and the second connection portion is different from each other.

[0070] The intersection 82c allows the first wiring 82a and the second wiring 82b to cancel out the effects of magnetic flux generated in the region adjacent to the intersection 82c. Specifically, for example, in FIG. 8, the first magnetic flux generated by the first wiring 82a and the second wiring 82b in the region adjacent to the upper side of the intersection 82c and the second magnetic flux generated by the first wiring 82a and the second wiring 82b in the region adjacent to the lower side of the intersection 82c are in opposite directions and cancel each other out. This reduces noise in the feedback signal. Even with a configuration having multiple intersections 82c as shown in FIG. 9, the noise reduction effect is similar to that of the configuration shown in FIG. 8.

[0071] In this way, a commonly used conductive wire can be used as the feedback wiring 82, and a noise reduction effect can be obtained. This eliminates the need to use a twisted wire in which two wires are twisted together in advance, or colored wires for identifying electrical wiring or circuits. Since twisted wires and colored wires are expensive, this allows for a reduction in manufacturing costs.

[0072] The surfaces of the winding N and the feedback wiring 82 may be covered with insulating tape, which also provides the same noise reduction effect as above.

[0073] FIG. 14 is a schematic side view showing a fourth example of a configuration in which FIG. 2 in the first embodiment is viewed from the direction indicated by arrow A. As shown in FIG. 14, the fourth example has a configuration basically similar to that of the first example, and therefore, as with the other examples, some of the description will be omitted. In FIG. 14, the drawn-out end of the winding N and the feedback wiring 82 are wound around and connected to the same pin. That is, in the transformer 20 of FIG. 14, both the third winding N3 and the second wiring 82b of the feedback wiring 82 are connected to the first pin 24a2, which serves as a terminal. The third winding N3 shown in FIG. 14 is the same as the third winding N3 shown in FIG. 2.

[0074] In particular, when the winding N and the feedback wiring 82 are at approximately the same potential, both the winding N and the feedback wiring 82 can be connected to the same terminal, the first pin 24a. Specifically, the ground GND1 (encircled by the dotted line in FIG. 1) on one side of the third winding N3 and the ground GND2 (encircled by the dotted line in FIG. 1) on one side of the feedback wiring 82 are at approximately the same potential. Therefore, as shown in FIG. 14, both the third winding N3 and the second wiring 82b can be connected to the first pin 24a2. This allows the number of pins to be reduced.

[0075] Second Embodiment <Basic Configuration> Fig. 15 is a circuit block diagram of a switching power supply device according to a second embodiment. Fig. 16 is a schematic perspective view of a module included in the switching power supply device according to the second embodiment. Fig. 17 is a schematic perspective view of the transformer shown in Fig. 16 with the transformer removed. Fig. 18 is a schematic cross-sectional view of a portion taken along line XVIII-XVIII in Fig. 17. Fig. 19 is a schematic side view showing an example of the transformer shown in Fig. 16 as viewed from the front direction indicated by arrow B. Figs. 15, 16, 17, 18, and 19 correspond to Figs. 1, 2, 4, 5, and 8 in the first embodiment.

[0076] 15 to 19, the second embodiment has a configuration basically similar to that of the first embodiment, and therefore the same components as those of the first embodiment are designated by the same reference numerals, and unless there are particular changes, their description will not be repeated. Power supply device 1000 of the second embodiment differs from that of the first embodiment in the following three points.

[0077] First, in this embodiment, the height direction of the cylindrical shape of the winding N (the direction in which the central axis of the winding N extends) is along the X direction. Therefore, in FIG. 16 , the winding N is tilted along the horizontal direction. The height direction of the cylindrical shape of the winding N may also be along the Y direction. The height direction of the cylindrical shape of the winding N may also be along any direction on the XY plane. The height direction of the cylindrical shape of the winding N may also extend along a direction inclined with respect to both the X direction and the Y direction on the XY plane. Because the winding N is cylindrical and extends in the X direction, the bobbin core 25C is cylindrical and extends along the X direction. The bobbin ends 25D are formed at both ends of the cylindrical, e.g., cylindrical, bobbin core 25C in the X direction.

[0078] 18 , core core portion 21C extends along the X direction when installed in transformer 20. In other words, the extension direction of core core portion 21C is along a direction perpendicular to the direction from first substrate 100 to second substrate 200. This is because the direction from first substrate 100 to second substrate 200 is along the Z direction.

[0079] For this reason, as shown by arrow D in FIG. 16 , the first core 21A is installed from the left side of the bobbin 25 in the X direction. Also, as shown by arrow D' in FIG. 16 , the second core 21B is installed from the right side of the bobbin 25 in the X direction. The core core portion 21C is inserted into a cavity inside the wall surface S1 of the bobbin core portion 25C, as in the first embodiment. As shown in FIG. 18 , the cross-sectional shapes of the bobbin 25, the first core 21A, and the second core 21B are the same as in the first embodiment. It is preferable that the rightmost portion of the first core 21A and the leftmost portion of the second core 21B are in contact with each other with almost no gap between them, and that they be arranged to form a single core 21.

[0080] Second, in this embodiment, a 0.5-turn winding is formed by each of the two feedback wirings 82, the first wiring 82a and the second wiring 82b. This winding is shown in FIG. 15 as the coil 32 formed on the feedback wiring 82. The coil 32 is, for example, a common mode choke coil. In other words, the coil 32 is configured as a winding wound around the core 21 by only 0.5 turns.

[0081] As shown in particular in FIGS. 16 and 19 , one wire extends upward from each of two of the plurality of first pins 24 a. The wire extends to each of two of the plurality of second pins 24 b. Along the way, i.e., between the first pin 24 a and the second pin 24 b, two first wirings 82 a and 82 b make a half turn, or 0.5 turns, along the circumferential direction of the winding N. These wires intersect at an intersection 82 c, as shown by the dotted lines in FIG. 19 , to form a twisted wire. This is indicated by the two feedback wirings 82 contacting each other at the center in the Z direction shown in FIG. 19 . As shown in FIGS. 16 , 18 , and 19 , the feedback wirings 82 of this embodiment extend along the Z direction. The extension direction of the feedback wirings 82 is arranged along the circumferential direction of the winding N, i.e., the direction indicated by the arrow R in FIG. 16 . More specifically, the direction in which the portion of the feedback wiring 82 adjacent to the winding N extends is along the circumferential direction of the winding N, which is the direction in which the winding N extends, that is, along the direction indicated by arrow R in FIG.

[0082] 18 , the shield winding N4 is wound on the outermost side of the winding N from the core core portion 21C and the bobbin core portion 25C. An insulating tape 23A is arranged so as to contact the outermost peripheral surface of the shield winding N4. A gap S2 is formed between this insulating tape 23A and the outer core portion 21D. In other words, the outermost peripheral surface of the shield winding N4 faces the outer core portion 21D across the gap S2.

[0083] The feedback wiring 82 is disposed in this gap S2. As described above, the feedback wiring 82 extends in the direction of arrow R, which is the circumferential direction of the winding N. Therefore, at the position of the cross-sectional view in Figure 18, the two feedback wirings 82 extend along the Z direction. The two feedback wirings 82 in Figure 18 correspond to the first wiring 82a and the second wiring 82b, which constitute the coil 32 (see Figure 15).

[0084] 18, the gap S2 is formed between one bobbin end 25D and the other bobbin end 25D in the X direction. Therefore, the pair of feedback wirings 82 passing through the gap S2 passes between one bobbin end 25D and the other bobbin end 25D in the X direction. This will be explained next.

[0085] 20 is a side view showing the process of installing the first and second cores of the second embodiment so that they are inserted into a cavity inside the bobbin core. (a) in FIG. 20 shows a case in which the feedback wiring 82 extending along the Z direction passes to the left of the left bobbin end 25D. In other words, (a) in FIG. 20 shows the feedback wiring 82 passing outside the area between one bobbin end 25D and the other bobbin end 25D in the X direction. In this case, the first core 21A, which is installed as shown by arrow D, comes into contact with the feedback wiring 82. In other words, when the first core 21A is installed on the bobbin 25 from the direction indicated by arrow D in FIG. 16, the first core 21A and the feedback wiring 82 interfere with each other. This results in poor workability when installing the first core 21A. Furthermore, there is a possibility of an electrical short circuit between the first core 21A and the feedback wiring 82.

[0086] On the other hand, FIG. 20B shows a case in which the feedback wiring 82 extending along the Z direction passes to the right of the left bobbin end 25D. That is, in FIG. 20B, the feedback wiring 82 passes through the area sandwiched between one bobbin end 25D and the other bobbin end 25D in the X direction. In this case, as indicated by arrow D, the first core 21A and the feedback wiring 82 do not come into contact with each other. This does not impair the workability of installing the first core 21A. Furthermore, this reduces the possibility of an electrical short circuit between the first core 21A and the feedback wiring 82. From this perspective, it is preferable that the feedback wiring 82 pass through the area sandwiched between a pair of bobbin ends 25D. The feedback wiring 82 installed in this manner enables the transmission of a feedback signal.

[0087] In FIG. 18 , the two feedback wirings 82 are arranged at the left end of the gap S2 in the X direction, i.e., on the most negative side in the X direction. However, the arrangement of the feedback wirings 82 is not limited to this. The feedback wirings 82 may be arranged, for example, in the center of the gap S2 in the X direction or at the right end in the X direction. Also, in FIG. 18 , the feedback wirings 82 and the outer-core portion 21D appear to be in contact with each other in the radial direction, i.e., the Y direction. However, in reality, a gap is formed between the feedback wirings 82 and the outer-core portion 21D. Alternatively, an insulating member may be arranged between the feedback wirings 82 and the outer-core portion 21D. For example, a coating made of an insulating material may be formed on the surface of the outer-core portion 21D facing the gap S2. In this way, the feedback wirings 82 and the outer-core portion 21D are not in direct contact with each other, and therefore are not electrically short-circuited.

[0088] Third, the second embodiment differs from the first embodiment in the shape of the bobbin 25. Specifically, as shown in Figures 16 and 17, the bobbin 25 of this embodiment does not have a member corresponding to the pin penetration portion 25E (see Figure 7) that protrudes from the bobbin end 25D. Through holes are formed at the upper and lower ends of the bobbin end 25D in the Z direction, allowing the first pin 24a and the second pin 24b to pass through and extend in the Z direction.

[0089] Standoffs 25F are formed at the top of the bobbin end 25D. The standoffs 25F protrude upward from the area where the pin passes through. The standoffs 25F extend upward from one and the other ends of the bobbin end 25D in the Y direction, adjacent to the portion where the pin passes through. Similarly, standoffs 25F are formed at the bottom of the bobbin end 25D. The standoffs 25F protrude downward from the area where the pin passes through. The standoffs 25F extend downward from one and the other ends of the bobbin end 25D in the Y direction, adjacent to the portion where the pin passes through. In this embodiment, the standoffs 25F are formed to include the same plane as the main surface of the bobbin end 25D. In this respect, this embodiment differs from embodiment 1, in which the standoffs 25F form a plane that intersects with the main surface of the bobbin end 25D.

[0090] <Operation and Effect> In the power supply device 1000 according to this embodiment, the transformer 20 includes a core 21 and a winding N wound around the core 21. The feedback wiring 82 is arranged along the direction indicated by the arrow R, which is the extension direction of the winding N. In other words, the feedback wiring 82 extends along the Z direction. As a result, the feedback wiring 82 forms a coil 32 with 0.5 turns, in which the core 21 is a magnetic material. The coil 32 is a common mode choke coil. Therefore, the feedback wiring 82 can suppress the occurrence of common mode noise in the transmitted feedback signal.

[0091] 16, the first wiring 82a and the second wiring 82b as the feedback wiring 82 are arranged adjacent to each other and wound 0.5 turns. In the 0.5 turn portions of the first wiring 82a and the second wiring 82b, the applied voltages cancel each other out, so the effect on voltage control is minimal.

[0092] Furthermore, the feedback wiring 82 may form leakage inductance, which forms a normal mode choke coil in the feedback wiring 82. By including a normal mode choke coil in the feedback wiring 82, the feedback wiring 82 can suppress the occurrence of normal mode noise in the transmitted feedback signal.

[0093] In the power supply device 1000, the transformer 20 includes a core 21 and a winding N wound around the core 21. The core 21 includes a core core portion 21C around which the winding N is wound, and a core outer portion 21D that is connected to the core core portion 21C and faces the outermost surface of the winding N across a gap S2. The feedback wiring 82 is disposed in the gap S2. This configuration may be adopted. In this case, it is possible to prevent problems such as interference between the core 21 and the feedback wiring 82 during installation of the core 21 in the transformer 20.

[0094] In the power supply device 1000, the transformer 20 includes a core 21 and a winding N wound around the core 21. The core 21 has a core core portion 21C around which the winding N is wound. The first substrate 100 and the second substrate 200 are arranged to face each other with the transformer 20 sandwiched between them. The extension direction of the core core portion 21C is a direction along the XY plane, which is a direction perpendicular to the direction from the first substrate 100 to the second substrate 200. In other words, the central axis of the winding N extends in a direction along the XY plane.

[0095] If the winding N is tilted horizontally as in the present embodiment, the height of the winding N can be made lower than in the first embodiment, where the winding N is upright along the vertical direction. In other words, the distance in the Z direction between the first substrate 100 and the second substrate 200 can be shortened. The upright configuration described above means that the central axis of the winding N extends in the Z direction, which is the direction from the first substrate 100 to the second substrate 200. This allows the dimension of the module 300 in the Z direction to be reduced. Therefore, the power supply device 1000 can be made smaller than in the first embodiment.

[0096] Third Embodiment <Basic Configuration> Fig. 21 is a schematic perspective view of a module included in a switching power supply device according to a first example of the third embodiment. As shown in Fig. 21, the first example of the third embodiment has a configuration basically similar to that shown in Fig. 2 of the first embodiment, and therefore the same components as those in Fig. 2 are given the same reference numerals, and their description will not be repeated unless there are particular changes. Fig. 22 is a schematic perspective view of a module included in a switching power supply device according to a second example of the third embodiment. As shown in Fig. 22, the second example of the third embodiment has a configuration basically similar to that shown in Fig. 16 of the second embodiment, and therefore the same components as those in Fig. 16 are given the same reference numerals, and their description will not be repeated unless there are particular changes. The power supply device 1000 according to the third embodiment differs from that according to the first embodiment in the extending direction of the pins.

[0097] 21 and 22, pads 24P are formed on one main surface of each of the first substrate 100 and the second substrate 200. The pads 24P are formed on the opposing main surfaces of the first substrate 100 and the second substrate 200. In other words, the pads 24P are formed on the upper main surface of the first substrate 100 and the lower main surface of the second substrate 200.

[0098] In this embodiment, the first pin 24A is bonded to the main surface of the first substrate 100. The second pin 24B faces the lower main surface of the second substrate 200 (see FIG. 2). The second pin 24B is bonded to the main surface of the second substrate 200. More specifically, at least one of the first pin 24A and the second pin 24B includes an end portion that extends in a direction along the main surface of either the first substrate 100 or the second substrate 200. The end portion of the pin is bonded to a pad 24P on the main surface of the substrate.

[0099] In Figures 21 and 22, the end of the first pin 24A extends in a direction along the XY plane along the main surface of the first substrate 100. For this reason, the first pin 24A may be bent at its end so that the extension direction changes by approximately 90° relative to the region other than the end. Similarly, in Figures 21 and 22, the end of the second pin 24B extends in a direction along the XY plane along the main surface of the first substrate 100. For this reason, the second pin 24B may be bent at its end so that the extension direction changes by approximately 90° relative to the region other than the end. Note that the second pin 24B is hidden and cannot be seen in Figures 21 and 22. This portion may be joined using a through-hole h, as in embodiments 1 and 2. That is, the pin may be inserted into the through-hole h, and the pin and the substrate may be joined by a soldering process.

[0100] In this embodiment, the shape of the bobbin 25 is not taken into consideration. In Fig. 21, the uppermost and lowermost portions of the bobbin 25 in the Z direction are shown as having shapes that follow the XY plane. While such a shape is acceptable, the bobbin 25 may also have a shape that includes a pin-through portion 25E and a standoff 25F, similar to the bobbin 25 of the first embodiment. This also applies to the example shown in Fig. 22 below.

[0101] In particular, the second example in Fig. 22 is an arrangement of the configuration of embodiment 2. Therefore, similar to Fig. 18 of embodiment 2, the feedback wiring 82 may be arranged in the gap S2 between the outermost peripheral surface of the winding N and the core outer portion 21D. Alternatively, the feedback wiring 82 may be arranged so as to contact and run along the insulating tape 23A in Fig. 18. This makes it possible to prevent problems such as interference between the core 21 and the feedback wiring 82 when installing the core 21 in the transformer 20.

[0102] <Operation and Effect> In power supply device 1000 according to the present embodiment, transformer 20 includes first pin 24A joined to the main surface of first substrate 100 and second pin 24B joined to the main surface of second substrate 200. At least one of first pin 24A and second pin 24B includes an end portion extending in a direction along the main surface of either first substrate 100 or second substrate 200. The end portion is joined to the main surface.

[0103] By configuring the pins to be bonded to pads 24P on the main surface of the substrate, it is possible to eliminate the configuration in which the pins penetrate the substrate and protrude from the substrate, and therefore the overall dimension of module 300 in the Z direction, for example, can be reduced by the dimension of the portion of the pin that protrudes from the substrate in the first and second embodiments.

[0104] Furthermore, by eliminating the configuration in which pins protrude from the substrate, the component mountable area on the main surface of the substrate opposite the side having the pads 24P can be expanded. In other words, almost the entire lower main surface of the first substrate 100 and the upper main surface of the second substrate 200 can be used as a component mountable area. At least the area of ​​each main surface that was previously used for the protruding pins becomes the component mountable area. For example, an aluminum substrate can be bonded to the lower main surface of the first substrate 100 and the upper main surface of the second substrate 200, and the aluminum substrate can be connected to the housing of a mechanical device including the power supply device 1000. This utilizes the high thermal conductivity of the aluminum substrate to enhance the cooling effect of the power supply device 1000.

[0105] <Supplementary Note> In the second embodiment and the second example of the third embodiment, the extension direction of the winding N is along the vertical direction (Z direction). In these examples, as shown in FIG. 20, there is a possibility that the core 21 and the feedback wiring 82 may interfere with each other. For this reason, it is preferable to take the above-mentioned measures in these examples. On the other hand, in the first example of the first embodiment and the third embodiment, the extension direction of the winding N is along the horizontal direction. In these examples, there are cases where it is not necessary to consider interference between the core 21 and the feedback wiring 82. This will be explained using FIG. 23.

[0106] FIG. 23 is a schematic perspective view showing the process of inserting the first and second cores of the first embodiment into the hollow inside the bobbin core portion. As shown in FIG. 23 , the width of the first core 21A and the second core 21B inserted in the first embodiment in the X direction is narrower than that of the bobbin end 25D. Therefore, the first core 21A and the second core 21B are installed so as to overlap only a portion of the bobbin end 25D in a plan view from the Z direction. Here, the portion of the bobbin end 25D refers to the central portion of the bobbin end 25D in the X direction, including the hollow inside the wall surface S1. The core core portion 21C of the first core 21A is inserted from below into the hollow inside the wall surface S1. The core core portion 21C of the second core 21B is inserted from above into the hollow inside the wall surface S1. Therefore, the pin-through portions 25E protruding to the left of the left end of the bobbin end 25D in the X direction and to the right of the right end of the bobbin end 25D in the X direction do not come into contact with the core 21 at all.

[0107] The feedback wiring 82 is wound around the first pin 24A and the second pin 24B that pass through the pin penetration portion 25E. Therefore, the feedback wiring 82 is disposed at a position that substantially overlaps the pin penetration portion 25E in a plan view. In other words, the feedback wiring 82 does not overlap the core 21, which is disposed in only a partial region of the bobbin end 25D in the X direction, in a plan view. Therefore, the feedback wiring 82 and the core 21 are configured not to come into contact with each other or to short-circuit each other.

[0108] In all the embodiments, contact and short-circuiting between the winding N and the feedback wiring 82 can be prevented. This is because the outermost peripheral surface of the winding N, i.e., the outermost peripheral surface of the shield winding N4 in Fig. 5, is covered with insulating tape 23A. The presence of insulating tape 23A between the feedback wiring 82 and the winding N can prevent short-circuiting.

[0109] Fourth Embodiment. <Basic Configuration> Fig. 24 is a schematic perspective view of a module included in a switching power supply device according to a fourth embodiment. As shown in Fig. 24, this embodiment basically has the same configuration as Fig. 2 of the first embodiment and Fig. 16 of the second embodiment. For this reason, hereinafter, the same components as those in the first and second embodiments are given the same reference numerals, and unless there are particular changes, their description will not be repeated. The circuit block diagram of the power supply device including module 300 shown in Fig. 24 is similar to the circuit block diagram of power supply device 1000 in Fig. 15, and therefore its description will not be repeated. This fourth embodiment differs from the first and second embodiments in the configuration of transformer 20 and the manner in which transformer 20 is connected to first substrate 100 and second substrate 200.

[0110] As shown in Fig. 24, the transformer 20 of this embodiment includes a transformer substrate 26 in addition to the core 21 and the winding N. The transformer substrate 26 is, for example, a plate-like member with a rectangular main surface, and its thickness direction is along the X direction. Therefore, in Fig. 24, the main surface of the transformer substrate 26 is along the YZ plane. The core 21 is made up of two members: a first core 21A and a second core 21B.

[0111] FIG. 25 is a schematic perspective view showing the process of inserting portions of the first core and second core into cavities formed in a transformer substrate according to the fourth embodiment. As shown in FIG. 25 , a rectangular cavity S3 is formed in the center of the main surface of the transformer substrate 26. The cavity S3 penetrates the transformer substrate 26 in the thickness direction. In other words, the cavity S3 is a through-hole in the transformer substrate 26. The first core 21A and the second core 21B in FIG. 25 each have a core core portion 21C, a core outer portion 21D, and a core end portion 21E, similar to those in the first and second embodiments. However, the lengths of the core core portion 21C and the core outer portion 21D in the X direction are shorter than those in the first and second embodiments. Therefore, the X-direction dimension of the core 21 in FIG. 24 is much thinner than that of the second embodiment. This is because the core 21 in this embodiment is mounted on a transformer substrate 26 whose X-direction dimension is sufficiently smaller than that of the bobbin 25.

[0112] As indicated by arrow D in FIG. 25 , the core core portion 21C of the first core 21A is inserted into the cavity S3 from above. As indicated by arrow D' in FIG. 25 , the core core portion 21C of the second core 21B is inserted into the cavity S3 from below. Arrows D and D' in FIG. 25 correspond to arrows D and D' in FIG. 24 . This brings the outer core portion 21D of the first core 21A into contact with the outer core portion 21D of the second core 21B. The transformer substrate 26 is housed so as to be sandwiched between the core cutout portion 21F, which is surrounded by the core core portion 21C, the outer core portion 21D, and the core end portion 21E. In other words, at least a portion of the transformer substrate 26 is housed within the core 21. If the space between the pair of core cutout portions 21F is considered to be within the core 21, then the central portion of the transformer substrate 26, which is a partial region in the Z direction, is housed so as to be sandwiched within the core 21.

[0113] FIG. 26 is a schematic plan view of the transformer of embodiment 4 obtained through the process of FIG. 25 . FIG. 26 shows the transformer 20 as viewed from the positive side in the X direction, i.e., the right side of FIG. 24 . That is, FIG. 25 shows the transformer 20 of FIG. 26 before assembly, as viewed from the direction of arrow XXV in the figure. As shown in FIG. 26 , in the transformer 20 of embodiment 4, the core 21 is larger in dimension than the transformer substrate 26 in the Y direction. In the transformer 20, the transformer substrate 26 is larger in dimension than the core 21 in the Z direction. A terminal 29 is formed on the portion of the transformer substrate 26 that extends outside the core 21 in the Z direction. The terminal 29 has a first terminal 29 a and a second terminal 29 b. The first terminal 29 a is located on the negative side in the Z direction. The second terminal 29 b is located on the positive side in the Z direction. The first terminal 29 a and the second terminal 29 b are rectangular members formed of a conductive material. The first terminal 29a and the second terminal 29b are thin films.

[0114] As shown in FIG. 24 , the first substrate 100 has a through-hole H1 formed therethrough, penetrating from one main surface to the other main surface on the opposite side. The second substrate 200 has a through-hole H2 formed therethrough, penetrating from one main surface to the other main surface on the opposite side. However, the through-holes H1 and H2 in FIG. 24 are much larger than the through-hole h in FIG. 2 . The portion of the transformer substrate 26 at the bottom in the Z direction, including the first terminal 29 a, is inserted into and passes through the through-hole H1. The portion of the transformer substrate 26 at the top in the Z direction, including the second terminal 29 b, is inserted into and passes through the through-hole H2. The first terminal 29 a is electrically and mechanically connected to the first substrate 100 via the through-hole H1 by solder (not shown). The second terminal 29 b is electrically and mechanically connected to the second substrate 200 via the through-hole H2 by solder (not shown).

[0115] FIG. 27 is a schematic cross-sectional view of the substrate of FIG. 26. That is, FIG. 27 shows a schematic cross-sectional view of a portion along line XXVII-XXVII in FIG. 26. FIG. 28 is a schematic cross-sectional view showing an aspect in which a core is attached to the substrate of FIG. 27. The transformer substrate 26 may be a single substrate. However, as shown in FIGS. 27 and 28, the transformer substrate 26 may also be configured by stacking two or more substrates. Here, as an example, an explanation will be given using an example in which the transformer substrate 26 includes transformer substrates 26A, 26B, and 26C. Note that the transformer substrate 26D is provided for the convenience of later explanation.

[0116] Figure 29 is a schematic plan view of a substrate on which the first winding and feedback wiring are formed, among the transformer substrates of Figures 27 and 28. In Figure 29, (a) shows the transformer substrate 26A of Figures 27 and 28. In Figure 29, (b) shows the transformer substrate 26B of Figures 27 and 28. In Figure 29, (c) shows the transformer substrate 26C of Figures 27 and 28.

[0117] As shown in Figures 29(a) and 29(b), a first winding N1 is formed as the winding N on the transformer substrate 26A and the transformer substrate 26B. The first winding N1 is formed in a planar shape on the transformer substrate main surface, which is the main surface of the transformer substrates 26A and 26B. In other words, the winding N including the first winding N1 is a planar coil. The transformer substrate 26 has the same number of transformer substrate main surfaces as the number of substrates stacked to form the transformer substrate 26. The winding N is formed on at least one of the main surfaces of the transformer substrate 26, i.e., on one or more of the transformer substrate main surfaces.

[0118] The first winding N1 is formed in a rectangular spiral around the rectangular cavity S3, with a gap therebetween. In FIG. 29, the first winding N1 is formed with approximately three turns as an example. However, the number of turns of the winding is arbitrary. The winding N and feedback wiring on the main surface of the transformer substrate, including the second winding N2 (to be described later) and the feedback wiring, are all thin films made of conductive material. That is, the winding N and feedback wiring may include, for example, thin-film wires whose main component is aluminum or copper.

[0119] Each of the transformer substrates 26A, 26B, and 26C has, as its first terminals 29a, four first terminals 29a1, 29a2, 29a3, and 29a4, for example. Each of the transformer substrates 26A, 26B, and 26C has, as its second terminals 29b, four second terminals 29b1, 29b2, 29b3, and 29b4, for example. Terminals with the same reference numerals on each transformer substrate overlap each other in plan view due to the stacking of the transformer substrates. However, each terminal is a thin film, and the insulating body of the transformer substrate is interposed between each terminal in the thickness direction of the substrate. Therefore, in the stacked transformer substrates 26A, 26B, and 26C, terminals with the same reference numerals are electrically insulated from each other. Furthermore, the first terminal 29a1 and the second terminal 29b1 are located at approximately the same coordinate position in the Y direction. The first terminal 29a2 and the second terminal 29b2 are located at approximately the same coordinate position in the Y direction. The first terminal 29a3 and the second terminal 29b3 are located at approximately the same coordinate position in the Y direction. The first terminal 29a4 and the second terminal 29b4 are located at approximately the same coordinate position in the Y direction.

[0120] The first winding N1 of the transformer substrate 26A and the first winding N1 of the transformer substrate 26B are connected to form a single wire via a via V. The via V is a hole formed to pass through the transformer substrate 26B. As a result, one end of the first winding N1 is connected to a first terminal 29a1 of the transformer substrate 26A, and the other end is connected to a first terminal 29a2 of the transformer substrate 26B.

[0121] The first winding N1 may extend over substantially the entire region between the first terminal 29 a and the second terminal 29 b in the Z direction, and may extend over substantially the entire region from the position where the first terminal 29 a 1 is disposed to the position where the first terminal 29 a 4 is disposed in the Y direction.

[0122] 28 and 29(a) and (b), the first winding N1 is arranged so as to be wound around the core core portion 21C inserted into the cavity S3. This results in a configuration similar to that of the first embodiment (see FIG. 5) in which the first winding N1 is arranged so as to be wound around the bobbin core portion 25C into which the core core portion 21C is inserted.

[0123] As shown in FIG. 29C, a feedback wiring 82 is formed on the transformer substrate 26C. The feedback wiring 82 is formed in a planar shape on the transformer substrate main surface, which is the main surface of the transformer substrate 26C. The feedback wiring 82 includes two wirings: a first wiring 82a and a second wiring 82b. The first wiring 82a connects the first terminal 29a3 and the second terminal 29b3. The second wiring 82b connects the first terminal 29a4 and the second terminal 29b4. The first wiring 82a and the second wiring 82b extend along the Z direction. Meanwhile, the first winding N1 also has a portion that extends long along the Z direction, which is the longitudinal direction of the transformer substrate 26. Therefore, the feedback wiring 82 is arranged along the Z direction, which is the extension direction of the winding N.

[0124] As a result, as shown in FIGS. 27 and 28, the first winding N1 and the feedback wiring 82 may be arranged to overlap each other by stacking the transformer substrates 26.

[0125] 30 is a schematic plan view of a transformer substrate shown in FIGS. 27 and 28 on which the second winding, the third winding, and the fourth winding are formed. In this embodiment, as in the first embodiment, the winding N includes a second winding N2, a third winding N3, and a shield winding N4 in addition to the first winding N1. In FIG. 30, the transformer substrate 26A shown in (a) and the transformer substrate 26B shown in (b) are formed with either the second winding N2, the third winding N3, or the shield winding N4. The second winding N2, the third winding N3, and the shield winding N4 in FIG. 30 are formed in the same manner as the first winding N1 in FIG. 29.

[0126] The transformer substrates 26A and 26B in FIG. 30 may be arranged as a two-layer transformer substrate 26D on the transformer substrate 26C in FIGS. 27 and 28. The order in which the transformer substrates 26A and 26B in FIG. 30 are stacked does not matter. That is, either the transformer substrate 26A or 26B may be arranged as the upper substrate of the two layers arranged as the transformer substrate 26D in FIG. 27. That is, the transformer substrate 26A may be arranged above or below the transformer substrate 26B. Furthermore, both the two-layer transformer substrates 26A and 26B on which the second winding N2 is formed and the two-layer transformer substrates 26A and 26B on which the third winding N3 is formed may be arranged in the area of ​​the two-layer transformer substrate 26D in FIGS. 27 and 28.

[0127] Alternatively, the transformer substrates 26A and 26B in FIG. 30 may be arranged in two layers stacked between the feedback wiring 82 and the first winding N1 in FIG. 27 and FIG. 28. Specifically, the space between the feedback wiring 82 and the first winding N1 here refers to the space between the transformer substrates 26B and 26C in FIG. 27 and FIG. 28. In this case, the stacking order of the transformer substrates 26A and 26B in FIG. 30 is irrelevant. Furthermore, both the two-layer transformer substrates 26A and 26B on which the second winding N2 is formed and the two-layer transformer substrates 26A and 26B on which the third winding N3 is formed may be arranged between the feedback wiring 82 and the first winding N1 in FIG. 27 and FIG. 28.

[0128] That is, in a first case, the feedback wiring 82 may be formed on the main surface of the transformer substrate 26C, which is the uppermost layer of the transformer substrate 26, which is made up of multiple stacked substrates. In this case, the feedback wiring 82 is formed on the main surface of the transformer substrate 26, which is the uppermost surface of the entire transformer substrate 26. Alternatively, in a second case, the feedback wiring 82 may be formed on the main surface of the transformer substrate 26C, which is a layer other than the uppermost layer of the transformer substrate 26, which is made up of multiple stacked substrates. In this case, the feedback wiring 82 is formed on the main surface of the transformer substrate 26, which is located inside the entire transformer substrate 26. In both the first case and the second case, the feedback wiring 82 is formed on one or more transformer substrate main surfaces within the core 21. The above feedback wiring 82 refers to the first wiring 82a and the second wiring 82b.

[0129] As a result, when there are multiple transformer substrates, the multiple transformer substrates including the transformer substrate 26C are stacked on top of each other, regardless of the position of the transformer substrate 26C. The first winding N1, the second winding N2, the third winding N3, the shield winding N4, and the feedback wiring 82 are formed on each transformer substrate.

[0130] Each winding N is formed as a thin film on the main surface of the transformer substrate. Therefore, different types of windings N, such as the first winding N1 and the second winding N2, are electrically insulated from each other because the insulating body of the transformer substrate is interposed between the different types of windings N. The insulating material that makes up the body of the transformer substrate 26 corresponds to the insulating tape 23A between each winding N in the first embodiment.

[0131] 27 to 30, the winding N and the feedback wiring 82 are connected to the terminal 29. However, even in this embodiment, the first pin 24a and the second pin 24b (see FIG. 4) may protrude from the transformer substrate 26, for example. In this case, the feedback wiring 82 is wound around the first pin 24a and the second pin 24b. The first pin 24a may be joined to the main surface of the first substrate 100, and the second pin 24b may be joined to the main surface of the second substrate 200.

[0132] 31 is a schematic plan view showing a first modified example of a transformer substrate on which feedback wiring is formed. As shown in (a) and (b) of FIG. 31, a transformer substrate 26C on which feedback wiring 82 is formed may be divided into two layers. (a) of FIG. 31 shows a transformer substrate 26C1, which is one of the two-layer transformer substrates 26C. (b) of FIG. 31 shows a transformer substrate 26C2, which is the other of the two-layer transformer substrates 26C.

[0133] A first wiring 82a is formed on the main surface of the transformer substrate 26C1. The first wiring 82a is bent on the main surface. As a result, the first wiring 82a connects the first terminal 29a4 and the second terminal 29b3. A second wiring 82b is formed on the main surface of the transformer substrate 26C2. The second wiring 82b is bent on the main surface. As a result, the second wiring 82b connects the first terminal 29a3 and the second terminal 29b4. In this respect, FIG. 31 differs in configuration from FIG. 29(c), in which both the first wiring 82a and the second wiring 82b are formed on a single-layer transformer substrate 26C. In this way, by being formed on different main surfaces of the transformer substrate, the first wiring 82a and the second wiring 82b may intersect in a planar view. By intersecting in a planar view, the first wiring 82a and the second wiring 82b are twisted wires. Therefore, the same intersection 82c as in the first embodiment is formed in the present embodiment, and the same effects as those of the intersection 82c can be obtained.

[0134] FIG. 32 is a schematic plan view showing a second modification of a transformer substrate on which a feedback wiring is formed. The second wiring 82b in FIGS. 32(a) and 32(b) is connected to form a single wiring between two transformer substrates 26C via vias V. In this manner, the second wiring 82b may be formed across multiple transformer substrates. Therefore, the second wiring 82b may include a bent portion that intersects the first wiring 82a in a three-dimensional manner on a transformer substrate 26C2 that is different from the transformer substrate 26C1 on which the first wiring 82a is formed. As a result, the second wiring 82b in FIG. 32 has one end connected to the second terminal 29b4 of the transformer substrate 26C1 and the other end connected to the first terminal 29a3 of the transformer substrate 26C2, as in FIG. 31 .

[0135] 33 is a schematic enlarged view of the portion where the transformer, the first substrate, and the second substrate are connected in embodiment 4. As shown in FIG. 33, the Y-direction width at the top and bottom in the Z direction of transformer substrate 26 is smaller than the Y-direction width at the center. Because the width is narrower, the portion indicated by the dotted line in transformer substrate 26 is missing. The missing portion of transformer substrate 26 is designated missing portion 27.

[0136] The uppermost surface of the notched portion 27 on the lower side of the transformer substrate 26 in the Z direction is referred to as the top surface 27a. As a result, the upper main surface of the first substrate 100, through which the transformer substrate 26 passes through the through-hole H1, comes into contact with the top surface 27a. The lowermost surface of the notched portion 27 on the upper side of the transformer substrate 26 in the Z direction is referred to as the bottom surface 27b. As a result, the lower main surface of the second substrate 200, through which the transformer substrate 26 passes through the through-hole H2, comes into contact with the bottom surface 27b.

[0137] The first substrate 100 and the second substrate 200 can be installed so that they come into contact with the top surface 27a and the bottom surface 27b of the notched portion 27. This allows the distance in the Z direction between the first substrate 100 and the second substrate 200 to be kept constant. In other words, the distance in the Z direction between the first substrate 100 and the second substrate 200 can be made equal to the distance in the Z direction between the top surface 27a and the bottom surface 27b. Therefore, when multiple power supply devices 1000 are manufactured, the distance between each of the first substrate 100 and the second substrate 200 can be made equal.

[0138] The notches 27 may be formed in the above-mentioned locations, i.e., at one and the other ends of the shorter sides of the rectangle of the main surface of the transformer substrate. However, the notches 27 may also be formed in locations other than those mentioned above. For example, the notches 27 may be formed in the portions between the plurality of first terminals 29a and the portions between the plurality of second terminals 29b provided on the transformer substrate 26. In this case, the first substrate 100 and the second substrate 200 may have protrusions that come into contact with the notches 27.

[0139] As shown in FIGS. 29 to 32, the width of the transformer substrate 26 in the Y direction at the top and bottom in the Z direction may be greater than the width in the Y direction at the center.

[0140] <Effects> In the power supply device 1000 according to this embodiment, the transformer 20 further includes a transformer substrate 26. The transformer substrate 26 has a winding N formed thereon, at least a portion of which is housed within the core 21. The winding N is a planar coil formed in a plane on at least one of the transformer substrate main surfaces that exist as the main surface of the transformer substrate 26. The feedback wiring 82 is formed on the transformer substrate main surface within the core 21.

[0141] Fig. 34 is a schematic plan view of a transformer serving as a comparative example of the fourth embodiment. As shown in Fig. 34, the transformer 20 of the comparative example has basically the same configuration as the transformer 20 shown in Fig. 26. However, the shape of the transformer substrate 26 and the arrangement of the feedback wiring 82 in the comparative example are different from those of the transformer 20 shown in Fig. 26. In the transformer 20 of the comparative example shown in Fig. 34, the winding N is formed in a portion of the transformer substrate 26 that is hidden within the core 21 and cannot be seen. In the transformer 20 of the comparative example, the feedback wiring 82 is arranged outside the core 21.

[0142] In this case, it is preferable that a cavity S4 be formed in the transformer substrate 26 in addition to the cavity S3. The Y-direction position of cavity S3 overlaps with the Y-direction positions of the first terminals 29a1 and 29a2 and the region between them. This allows the winding N to be wound around cavity S3. In contrast, it is preferable that the Y-direction position of cavity S4 overlaps with the Y-direction position of the region between first terminals 29a2 and 29a3. This results in cavity S4 being formed in the region between the winding N formed approximately at the position of the first terminals 29a1 and 29a2 and the feedback wiring 82 formed approximately at the position of the first terminals 29a3 and 29a4. Neither the winding N nor the feedback wiring 82 passes through this region. This allows the outer core portions 21D of the first core 21A and second core 21B to be inserted so as to penetrate cavity S4. In this way, as shown in FIG. 34, it is possible to form a transformer 20 in which only the winding N is housed within the core 21 and the feedback wiring 82 is arranged outside the core 21.

[0143] 34, however, the problem of the size of the transformer 20 increases because the size of the transformer substrate 26 in the Y direction increases.

[0144] Therefore, in this embodiment, as shown in, for example, FIGS. 28 to 32, the transformer 20 is configured such that both the winding N and the feedback wiring 82 are housed within the core 21. In this way, the transformer substrate 26 can be made smaller than the comparative example in FIG. 34. This is because the Y-direction dimension of the cavity S4 in FIG. 34 is not required. As a result, the winding N and the feedback wiring 82 can be brought closer together and can partially overlap in a plan view. Therefore, by making the transformer substrate 26 smaller, the entire transformer 20 can be made smaller.

[0145] By reducing the size of the transformer substrate 26, a larger number of transformer substrates 26 can be formed from the same amount of material.

[0146] Furthermore, in this embodiment, a planar coil is used as the coil, instead of the winding N wound around the bobbin 25. The planar coil is a thin film formed in a planar shape on the main surface of the transformer substrate. This reduces variations in the quality of the winding N. As a result, the yield of the transformer 20 is improved.

[0147] It should be noted that there is no restriction on the type of winding N formed on each of the transformer substrates 26A to 26C and the type of feedback wiring 82. There is also no restriction on the type of terminal 29 connected to each winding N and feedback wiring 82. Furthermore, there is no restriction on the order in which the first winding N1, the second winding N2, the third winding N3, and the shield winding N4 are stacked in the Z direction.

[0148] <Other Effects> The other effects of this embodiment are basically the same as those described above in the first and second embodiments. That is, a feedback signal for monitoring and adjusting the output voltage of the secondary circuit 201 can be transmitted to the control circuit 101b via the photocoupler 81. It is possible to achieve all of the following: high accuracy of the output voltage at the output terminal OUT, variability of the output voltage, and improved output voltage responsiveness to power fluctuations. This effect can be obtained even if the first substrate 100 and the second substrate 200 are independent of each other.

[0149] In this embodiment, a feedback wiring 82 is disposed within the core 21 of the transformer 20. This feedback wiring 82 forms a coil 32 (see FIG. 15 ) with 0.5 turns, with the core 21 being a magnetic material. The coil 32 is a common mode choke coil. Therefore, the feedback wiring 82 can suppress the occurrence of common mode noise in the transmitted feedback signal.

[0150] The features described in the above-described embodiments may be applied in appropriate combinations within the scope of technical compatibility.

[0151] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The basic scope of the present disclosure is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims.

[0152] 10 Primary circuit installation portion, 12 Secondary circuit installation portion, 20 Transformer, 21 Core, 21A First core, 21B Second core, 21C Core core portion, 21D Core outer portion, 21E Core end portion, 21F Core notch portion, 23A Insulating tape, 23B Barrier tape, 24a, 24a1, 24a2 First pin, 24b, 24b1, 24b2 Second pin, 24P Pad, 25 Bobbin, 25C Bobbin core portion, 25D Bobbin end portion, 25E ​​Pin penetration portion, 25F Standoff, 26, 26A, 26B, 26C, 26C1, 26C2, 26D Transformer board, 27 Missing portion, 27a Top surface, 27b Bottom surface, 29 Terminals, 29a, 29a1, 29a2, 29a3, 29a4: first terminals, 29b, 29b1, 29b2, 29b3, 29b4: second terminals, 32: coil, 80: feedback wiring section, 81: photocoupler, 82: feedback wiring, 82a: first wiring, 82b: second wiring, 82c: intersection, 100: first substrate, 101: primary circuit, 101a: switching circuit, 101b: control circuit, 120: substrate, 200: second substrate, 201: secondary circuit, 201a: rectifier circuit, 201b: feedback circuit, 300: module, 1000: power supply device, AA: pattern gap, BB: wiring pattern gap, h, H1, H2: through hole, IN: input terminal, N: winding, N1: first winding, N2: second winding, N3: third winding, N4 Shield winding, OUT output terminal, S1 wall, S2 air gap, S3, S4 cavity, V via.

Claims

1. A switching power supply device comprising: a first substrate on which a primary circuit that receives power from an input terminal is formed; a second substrate on which a secondary circuit that can transmit power to the outside from an output terminal is formed; a switching transformer that is interposed between the first substrate and the second substrate and converts power; and a feedback wiring section, wherein the second substrate is a substrate separate from the first substrate, the secondary circuit includes a feedback circuit that generates a feedback signal related to the power output from the output terminal, and the feedback signal is transmitted from the secondary circuit to the primary circuit via the feedback wiring section.

2. The switching power supply device according to claim 1, wherein the primary circuit includes a switching circuit that receives power from the input terminal and a control circuit that controls the switching circuit and receives a feedback signal output from the feedback circuit; the secondary circuit includes a rectifier circuit connected to the output terminal; and the feedback wiring section includes a photocoupler.

3. A switching power supply device as described in claim 1 or 2, wherein the switching transformer includes a first pin joined to the main surface of the first substrate and a second pin joined to the main surface of the second substrate, and at least one of the first pin and the second pin includes an end portion extending in a direction along the main surface of either the first substrate or the second substrate, and the end portion is joined to the main surface.

4. The switching power supply device according to any one of claims 1 to 3, wherein the feedback wiring section includes feedback wiring installed in the switching transformer.

5. The switching power supply device according to claim 4, wherein the switching transformer includes a core and a winding wound around the core, and the extension direction of the feedback wiring intersects with the extension direction of the winding.

6. The switching power supply device according to claim 4, wherein the switching transformer includes a core and a winding wound around the core, and the feedback wiring is arranged along the extension direction of the winding.

7. The switching power supply device according to claim 6, wherein the switching transformer further includes a transformer substrate on which the winding is formed and at least a portion of which is housed within the core, the winding being a planar coil formed in a plane on at least one main surface of the transformer substrate, and the feedback wiring is formed on the main surface of the transformer substrate within the core.

8. The switching power supply device according to any one of claims 4 to 7, wherein the feedback wiring includes a wire material whose main component is aluminum or copper.

9. A switching power supply device according to any one of claims 4 to 8, wherein the feedback wiring includes a first wiring and a second wiring arranged along the first wiring, and the first wiring and the second wiring are twisted wires that cross each other at at least one point.

10. A switching power supply device as described in claim 9, wherein the first wiring is connected so that a first connection portion electrically connected to the first substrate and a second connection portion electrically connected to the second substrate are positioned at a position other than a position where they overlap each other in a planar view.

11. A switching power supply device as described in claim 9, wherein the second wiring is connected so that a first connection portion electrically connected to the first substrate and a second connection portion electrically connected to the second substrate are positioned at a position other than a position where they overlap each other in a planar view.

12. The switching power supply device according to claim 4, wherein the switching transformer includes a core, a winding wound around the core, and a terminal, the terminal being connected to the winding and the feedback wiring.

13. The switching power supply device according to claim 4, wherein the switching transformer includes a core and a winding wound around the core, the core including a central portion around which the winding is wound and an outer portion connected to the core and facing the outermost surface of the winding across a gap, and the feedback wiring is disposed in the gap.

14. A switching power supply device as described in claim 4, wherein the switching transformer includes a core and a winding wound around the core, the core having a core portion around which the winding is wound, the first substrate and the second substrate are arranged to face each other with the switching transformer in between, and the extension direction of the core portion is along a direction perpendicular to the direction from the first substrate to the second substrate.

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