Switching power supply device

Abstract

To provide a switching power supply device which is small in size, high in efficiency, and low in cost by noise suppression effects.SOLUTION: A switching power supply device 100 comprises: a power conversion circuit including an input capacitor CIN, an output capacitor COUT, a switching circuit 3B and an inductor; a common mode choke coil 1 provided between a DC power source and the power conversion circuit; and a multilayer circuit board on which the power conversion circuit and the common mode choke coil are mounted. The common mode choke coil includes: a first winding connected with a low potential side of the DC power source via a first reference potential wiring pattern P- and connected with a low potential side of a load via a second reference potential wiring pattern L-; and a second winding connected with a high potential side of the DC power source via a DC positive electrode potential wiring pattern P+ and connected with an input side of the power conversion circuit via an input positive electrode potential wiring pattern L+. In a view in a Z direction, the first and second reference potential wiring patterns are not overlapped, and the DC positive electrode potential wiring pattern and the input positive electrode potential wiring pattern are not overlapped.SELECTED DRAWING: Figure 6A

Description

[Technical field]

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

[0002] There is an increasing demand for switching power supplies that convert the voltage of direct current (hereinafter also referred to as "DC") power from an in-vehicle battery and supply power to the load of in-vehicle equipment. In recent years, as switching frequencies become higher and signals handled by in-vehicle equipment become faster, common mode noise problems in high frequency bands (e.g., 30 to 1000 MHz) have become evident. For example, technology has been disclosed relating to a printed multilayer circuit board that can suppress EMI (Electromagnetic Interference) radiation from power lines (e.g., Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2017 / 006552 Summary of the Invention [Problem to be solved by the invention]

[0004] Conventionally, common mode choke coils have been generally used as a countermeasure against common mode noise in low frequency bands (e.g., 0.15 MHz to 30 MHz). In such a configuration, a path may be formed through which common mode noise in high frequency bands (e.g., 30 to 1000 MHz) flows out without passing through the common mode choke coil.

[0005] The present disclosure has been made in consideration of the above, and has an object to provide a switching power supply device with improved noise suppression effect. [Means for solving the problem]

[0006] A switching power supply device according to one aspect of the present disclosure is a switching power supply device that converts a voltage input from a DC power supply into power and supplies the converted power to a load, the switching power supply device comprising: a power conversion circuit including an input capacitor, an output capacitor, a switching element, and an inductor; a common mode choke coil provided between the DC power supply and the power conversion circuit; and a multilayer circuit board on which the power conversion circuit and the common mode choke coil are mounted, the multilayer circuit board including an insulating base material, a first reference potential wiring pattern, a second reference potential wiring pattern, a DC positive potential wiring pattern, and an input positive potential wiring pattern, the first reference potential wiring pattern, the second reference potential wiring pattern, the DC positive potential wiring pattern, and the input positive potential wiring pattern each being an insulating base material. the common mode choke coil is provided on an insulating substrate, and the common mode choke coil has a first winding having one end connected to the low potential side of the DC power supply through a first reference potential wiring pattern and the other end connected to the low potential side of the load through a second reference potential wiring pattern, and a second winding having one end connected to the high potential side of the DC power supply through a DC positive potential wiring pattern and the other end connected to the input side of the power conversion circuit through an input positive potential wiring pattern, wherein the second reference potential wiring pattern is not provided in a region overlapping with the first reference potential wiring pattern when viewed in a planar view from a direction perpendicular to the plane of the insulating substrate, and the input positive potential wiring pattern is not provided in a region overlapping with the DC positive potential wiring pattern when viewed in a planar view from a direction perpendicular to the plane of the insulating substrate.

[0007] In this configuration, the switching noise generated by the switching operation of the switching elements is confined by the closed electric circuit, and the common mode noise that is conducted to the DC power supply is suppressed. Since the phase of the continuously generated switching noise is not constant, the noise is confined in the closed electric circuit, and is offset by each other. This effectively suppresses the radiation of the switching noise to the DC power supply and the outside, and effectively suppresses the generation of common mode noise due to noise propagation to the DC power supply.

[0008] A switching power supply device according to one aspect of the present disclosure is a switching power supply device that converts a voltage input from a DC power supply into power and supplies the converted power to a load, the switching power supply device comprising: a power conversion circuit including an input capacitor, an output capacitor, a switching element, and an inductor; a common mode choke coil provided between the DC power supply and the power conversion circuit; and a multilayer circuit board on which the power conversion circuit and the common mode choke coil are mounted, the multilayer circuit board including an insulating substrate, a first reference potential wiring pattern, a second reference potential wiring pattern, a DC positive potential wiring pattern, and an input positive potential wiring pattern, the first reference potential wiring pattern, the second reference potential wiring pattern, the DC positive potential wiring pattern, and the input positive potential wiring pattern are each provided on the insulating substrate, the common mode choke coil has one end connected to a low potential side of the DC power supply via the first reference potential wiring pattern, and has one end connected to a low potential side of the DC power supply via the second reference potential wiring pattern. and a second winding having one end connected to the high potential side of the DC power supply through a DC positive potential wiring pattern and the other end connected to an input side of the power conversion circuit through an input positive potential wiring pattern, wherein the second reference potential wiring pattern is not provided in a region overlapping with the first reference potential wiring pattern when viewed in a plan view from a direction perpendicular to the plane of the insulating substrate, and the input positive potential wiring pattern is not provided in a region overlapping with the DC positive potential wiring pattern when viewed in a plan view from a direction perpendicular to the plane of the insulating substrate, and the first reference potential wiring pattern, the second reference potential wiring pattern, the DC positive potential wiring pattern, the input positive potential wiring pattern, the power conversion circuit, and the common mode choke coil constitute a noise balancing circuit which is an electrically closed circuit, and the noise balancing circuit cancels out noise generated due to a switching operation of the switching element.

[0009] In this configuration, the switching noise generated by the switching operation of the switching elements is confined by the closed electric circuit, and the common mode noise that is conducted to the DC power supply is suppressed. Since the phase of the continuously generated switching noise is not constant, the noise is confined in the closed electric circuit, and is offset by each other. This effectively suppresses the radiation of the switching noise to the DC power supply and the outside, and effectively suppresses the generation of common mode noise due to noise propagation to the DC power supply. Effect of the Invention

[0010] According to the present disclosure, it is possible to provide a switching power supply device with an improved noise suppression effect. In particular, for electromagnetic noise caused by the switching operation of the switching elements constituting the power conversion circuit, the wiring pattern suppresses the radiation of electric field noise, and the noise balancing circuit, which is an electrically closed circuit, cancels the generation of electromagnetic noise, reducing the electromagnetic noise without converting it into thermal energy, thereby achieving high efficiency of the power conversion circuit. Due to the noise suppression effect, it is possible to provide a switching power supply device that is small, highly efficient, and low cost. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram showing a schematic configuration of a switching power supply device. [Diagram 2] FIG. 2 is a schematic configuration diagram illustrating an example of a power conversion circuit. [Diagram 3] FIG. 3 is a schematic diagram showing a modified example of the power conversion circuit. [Figure 4] FIG. 4 is a schematic cross-sectional view of a switching power supply device. [Figure 5A] FIG. 5A is a schematic top view of the switching power supply device according to the first embodiment. [Figure 5B] FIG. 5B is a schematic top perspective view of the switching power supply device according to the first embodiment. [Figure 5C] FIG. 5C is a schematic cross-sectional view taken along line AA' of the switching power supply device according to the first embodiment. [Figure 6A] FIG. 6A is a schematic top view of a switching power supply device according to the second embodiment. [Figure 6B] FIG. 6B is a schematic top perspective view of the switching power supply device according to the second embodiment. [Figure 6C] FIG. 6C is a schematic cross-sectional view taken along line AA' of the switching power supply device according to the second embodiment. [Figure 7A] FIG. 7A is a schematic top view of a switching power supply device according to embodiment 3. FIG. [Figure 7B] FIG. 7B is a schematic top perspective view of the switching power supply device according to the third embodiment. [Figure 7C] FIG. 7C is a schematic cross-sectional view taken along line AA' of the switching power supply device according to embodiment 3. [Figure 8] FIG. 8 is a diagram illustrating the effect of the switching power supply device according to the embodiment. [Figure 9] FIG. 9 is a diagram showing a noise propagation path in a configuration using a conventional common mode choke coil. [Figure 10] FIG. 10 is a perspective view illustrating an example of a common mode choke coil according to an embodiment. [Figure 11] FIG. 11 is a plan view of the common mode choke coil as viewed in the third negative direction. [Figure 12] FIG. 12 is a side view of the common mode choke coil as viewed in the second positive direction. [Figure 13] FIG. 13 is a plan view of the common mode choke coil as viewed in the third positive direction. [Figure 14] FIG. 14 is a side view of the common mode choke coil as viewed in the second negative direction. [Figure 15] FIG. 15 is a partial cross-sectional view of the common mode choke coil including the center axis of the winding core, a location of 1.0 turn of the first winding, and a location of 1.0 turn of the second winding. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, a power conversion device according to an embodiment will be described in detail with reference to the drawings. Note that the present disclosure is not limited to this embodiment. Each embodiment is an example, and it goes without saying that partial replacement or combination of the configurations shown in different embodiments is possible. From embodiment 2 onwards, a description of matters common to embodiment 1 will be omitted, and only the differences will be described. In particular, similar actions and effects due to similar configurations will not be mentioned in each embodiment.

[0013] 1 is a diagram showing a schematic configuration of a switching power supply device 100. The switching power supply device 100 converts direct current power (hereinafter also referred to as “DC”) input from a direct current power supply into a voltage and supplies the converted power to a load 2.

[0014] The switching power supply device 100 includes, as main components, a power conversion circuit 3 and a common mode choke coil 1 provided between a DC power supply and the power conversion circuit 3. The switching power supply device 100 according to the present disclosure is exemplified as being mounted on a vehicle, for example, and supplied with DC from an on-board battery through a power line such as a harness. Alternatively, the switching power supply device 100 may be mounted on an electric vehicle (EV) or a plug-in hybrid electric vehicle (PHEV), for example, and supplied with DC from an on-board battery charger (OBC) that converts commercial alternating current (hereinafter also referred to as "AC") power to DC and charges the on-board battery.

[0015] The common mode choke coil 1 includes a first winding 51 and a second winding 52 .

[0016] One end of the first winding 51 is connected to the low potential side of the DC power supply through a wiring pattern P-. The low potential side potential of the DC power supply is a first reference potential GND1. Hereinafter, the wiring pattern P- is also referred to as the "first reference potential wiring pattern P-."

[0017] The other end of the first winding 51 is connected to the low potential side of the load 2 through a wiring pattern L-. The low potential side potential of the load 2 is a second reference potential GND2. Hereinafter, the wiring pattern L- is also referred to as the "second reference potential wiring pattern L-".

[0018] One end of the second winding 52 is connected to the high potential side of the DC power supply through a wiring pattern P+. The high potential side potential of the DC power supply is the input positive potential VIN. Hereinafter, the wiring pattern P+ is also referred to as the "DC positive potential wiring pattern P+."

[0019] The other end of the second winding 52 is connected to the input side of the power conversion circuit 3 through a wiring pattern L+. The input side potential of the power conversion circuit 3 is approximately equivalent to an input positive potential VIN, which is the high-potential side potential of the DC power supply. Hereinafter, the wiring pattern L+ is also referred to as the "input positive potential wiring pattern L+".

[0020] An input capacitor CIN is connected between the input side of the power conversion circuit 3 and a second reference potential GND2. A DC voltage supplied from a DC power supply is applied across the input capacitor CIN.

[0021] An output capacitor COUT is connected between the output side of the power conversion circuit 3 and the second reference potential GND2. The output voltage of the power conversion circuit 3 is applied across the output capacitor COUT.

[0022] The high potential side of the load 2 is connected to the output side of the power conversion circuit 3 through a wiring pattern COUT+.

[0023] 2 is a schematic diagram showing an example of a power conversion circuit 3. The power conversion circuit 3 includes a DC-DC converter 3A.

[0024] 2, the DC-DC converter 3A includes a switching circuit 3B and an inductor L. The switching circuit 3B includes switching elements Q1 and Q2 and a control circuit 311. The switching elements Q1 and Q2 are exemplified by power semiconductor elements constituted by, for example, N-type MOS-FETs.

[0025] The switching element Q1 and the switching element Q2 are connected in series. More specifically, the source of the switching element Q1 and the drain of the switching element Q2 are connected.

[0026] An input capacitor CIN is connected between the drain of the switching element Q1 and the source of the switching element Q2. One end of an inductor L is connected to the connection point between the switching element Q1 and the switching element Q2, and an output capacitor COUT is connected between the other end of the inductor L and the source of the switching element Q2.

[0027] The gates of the switching elements Q1 and Q2 are each connected to a control circuit 311. The switching elements Q1 and Q2 are controlled by a control signal output from the control circuit 311.

[0028] The DC-DC converter is not limited to the above configuration, and may adopt a known configuration. Fig. 3 is a schematic diagram showing a modified example of a power conversion circuit. In the configuration shown in Fig. 2, a DC-DC converter including two switching elements Q1 and Q2 is exemplified, but as shown in Fig. 3, a configuration including one switching element Q and a diode element D may also be used. The present disclosure is not limited by differences in the configuration of the DC-DC converter.

[0029] In the above configuration, the common mode choke coil 1, the input capacitor CIN, the output capacitor COUT, and the inductor L are configured, for example, as surface mount devices (SMDs). The switching circuit 3B is configured, for example, as a switching regulator IC.

[0030] Fig. 4 is a schematic cross-sectional view of a switching power supply device. In the switching power supply device 100, an SMD including a common mode choke coil 1 and a switching regulator IC (switching circuit 3B) are mounted in the Z direction perpendicular to the XY plane on a multilayer circuit board 4 parallel to an XY plane including an X direction and a Y direction perpendicular to the X direction shown in Fig. 4.

[0031] The multilayer circuit board 4 has two or more wiring layers. In Fig. 4, the first wiring layer LY1 and the second wiring layer LY2 are provided with an insulating substrate DI sandwiched therebetween, but the multilayer circuit board 4 may have four or more wiring layers.

[0032] A common mode choke coil is generally used as a countermeasure against common mode noise in a low frequency band (for example, 0.15 MHz to 30 MHz). The self-resonant frequency of the common mode choke coil 1 is preferably 30 MHz or higher.

[0033] 1 and 4 show the paths of noise propagation. Common mode noise components in the low frequency band (for example, 0.15 MHz to 30 MHz) are cancelled out by the common mode choke coil as shown in FIG.

[0034] For example, as shown in Fig. 4, when viewed from the Z direction perpendicular to the XY plane (hereinafter also simply referred to as "planar view"), if the first reference potential wiring pattern P- provided on the first wiring layer LY1 and the second reference potential wiring pattern L- provided on the second wiring layer LY2 are configured to overlap, an unintended stray capacitance CS is formed between the first reference potential wiring pattern P- and the second reference potential wiring pattern L-. In the high frequency band, if the impedance of such unintended stray capacitance CS becomes smaller than the impedance of the common mode choke coil, an outflow path for common mode noise may be formed through the stray capacitance CS formed between the first reference potential wiring pattern P- and the second reference potential wiring pattern L-, as shown in Figs. 1 and 4.

[0035] Specifically, for example, in a configuration in which the switching power supply device 100 is mounted on a vehicle, the common mode noise that flows out through the stray capacitance CS reaches the vehicle battery through a power line such as a harness. The common mode noise that reaches the vehicle battery flows back to the DC-DC converter 3A due to the capacitive coupling (stray capacitance CX) between the reference potential (first reference potential GND1) of the vehicle (chassis) and the output point (connection point with the inductor L, see Figs. 2 and 3) of the switching circuit 3B. When the common mode noise reaches the vehicle battery, the noise flows into other vehicle devices that receive power from the vehicle battery, which may cause problems such as malfunctions of the other vehicle devices.

[0036] (Embodiment 1) Fig. 5A is a schematic top view of the switching power supply device according to embodiment 1. Fig. 5B is a schematic top see-through view of the switching power supply device according to embodiment 1. Fig. 5C is a schematic cross-sectional view along line A-A' of the switching power supply device according to embodiment 1. Fig. 5A shows a first wiring layer LY1 of the switching power supply device 100 according to embodiment 1 as seen from the Z direction. Fig. 5B shows a second wiring layer LY2 of the switching power supply device 100 according to embodiment 1 as seen from the Z direction.

[0037] In the examples shown in Figures 5A, 5B, and 5C, the second reference potential wiring pattern L- is not provided in the area overlapping with the first reference potential wiring pattern P- in plan view. Also, the input positive potential wiring pattern L+ is not provided in the area overlapping with the DC positive potential wiring pattern P+ in plan view. This makes it possible to prevent stray capacitance from being formed between the first reference potential wiring pattern P- and the second reference potential wiring pattern L-. Also, it makes it possible to prevent stray capacitance from being formed between the DC positive potential wiring pattern P+ and the input positive potential wiring pattern L+.

[0038] 5A, 5B, and 5C, the first reference potential wiring pattern P- provided in the first wiring layer LY1 and the first reference potential wiring pattern P- provided in the second wiring layer LY2 overlap in a plan view. Also, the second reference potential wiring pattern L- provided in the first wiring layer LY1 and the second reference potential wiring pattern L- provided in the second wiring layer LY2 overlap in a plan view.

[0039] As a result, the switching power supply device 100 of embodiment 1 comprises an electrical closed circuit consisting of a first reference potential wiring pattern P-, a second reference potential wiring pattern L-, a DC positive potential wiring pattern P+, an input positive potential wiring pattern L+, a power conversion circuit 3, and a common mode choke coil 1.

[0040] The switching noise generated by the switching operation of the switching circuit 3B is confined by the closed electric circuit, and the common mode noise that is conducted to the DC power supply is suppressed. Since the phase of the continuously generated switching noise is not constant, the noise is confined in the closed electric circuit, and thus offset by each other. In other words, this closed electric circuit functions as a noise balancing circuit that balances the switching noise and suppresses the generation of common mode noise. In other words, the switching power supply device 100 is equipped with a noise balancing circuit.

[0041] As a result, the switching power supply device 100 according to the first embodiment can suppress the generation of common mode noise by suppressing the external radiation of switching noise and the conduction of switching noise to the DC power supply, and can suppress the level of switching noise by the noise balancing circuit. That is, the switching power supply device 100 according to the first embodiment can effectively suppress the radiation of switching noise to the DC power supply and the outside, and can effectively suppress the generation of common mode noise due to noise propagation to the DC power supply.

[0042] In addition, by arranging the elements of the switching power supply device 100 in the following order, common mode choke coil 1, input capacitor CIN, switching regulator IC (switching circuit 3B), and output capacitor COUT, in approximately one direction (e.g., X direction), it is possible to prevent unintended stray capacitance from being formed.

[0043] In addition, in a structure with four or more layers that has a complex wiring structure, unintended stray capacitance is likely to be formed, so it is more effective to apply this method to a structure with four or more layers.

[0044] (Embodiment 2) Fig. 6A is a schematic top view of the switching power supply device according to embodiment 2. Fig. 6B is a schematic top see-through view of the switching power supply device according to embodiment 2. Fig. 6C is a schematic cross-sectional view along line A-A' of the switching power supply device according to embodiment 2. Fig. 6A shows a first wiring layer LY1 of the switching power supply device 100 according to embodiment 2 as seen from the Z direction. Fig. 6B shows a second wiring layer LY2 of the switching power supply device 100 according to embodiment 2 as seen from the Z direction.

[0045] In the example shown in FIG. 6A, FIG. 6B, and FIG. 6C, similarly to the first embodiment, the second reference potential wiring pattern L- is not provided in the area overlapping with the first reference potential wiring pattern P- in a plan view. Also, the input positive potential wiring pattern L+ is not provided in the area overlapping with the DC positive potential wiring pattern P+ in a plan view. This makes it possible to prevent stray capacitance from being formed between the first reference potential wiring pattern P- and the second reference potential wiring pattern L-. Also, it makes it possible to prevent stray capacitance from being formed between the DC positive potential wiring pattern P+ and the input positive potential wiring pattern L+.

[0046] 6A, 6B, and 6C, the second wiring layer LY2 is not provided in an area overlapping the first reference potential wiring pattern P- provided in the first wiring layer LY1 in a plan view. Also, the second reference potential wiring pattern L- provided in the first wiring layer LY1 and the second reference potential wiring pattern L- provided in the second wiring layer LY2 overlap in a plan view.

[0047] As a result, the first reference potential wiring pattern P-, the second reference potential wiring pattern L-, the DC positive potential wiring pattern P+, the input positive potential wiring pattern L+, the power conversion circuit 3, and the common mode choke coil 1 function as a noise balancing circuit that balances switching noise and suppresses the generation of common mode noise, similar to embodiment 1.

[0048] Thereby, the switching power supply device 100 according to the second embodiment can suppress the generation of common mode noise by suppressing the external radiation of switching noise and the conduction of switching noise to the DC power supply, as in the first embodiment, and can suppress the level of switching noise by the noise balancing circuit. That is, the switching power supply device 100 according to the second embodiment can effectively suppress the radiation of switching noise to the DC power supply and the outside, as in the first embodiment, and can effectively suppress the generation of common mode noise due to noise propagation to the DC power supply.

[0049] (Embodiment 3) Fig. 7A is a schematic top view of a switching power supply device according to embodiment 3. Fig. 7B is a schematic top see-through view of a switching power supply device according to embodiment 3. Fig. 7C is a schematic cross-sectional view along line A-A' of the switching power supply device according to embodiment 3. Fig. 7A shows a first wiring layer LY1 of the switching power supply device 100 according to embodiment 3 as seen from the Z direction. Fig. 7B shows a second wiring layer LY2 of the switching power supply device 100 according to embodiment 3 as seen from the Z direction.

[0050] In the example shown in FIG. 7A, FIG. 7B, and FIG. 7C, similarly to the first and second embodiments, the second reference potential wiring pattern L- is not provided in the area overlapping with the first reference potential wiring pattern P- in plan view. Also, the input positive potential wiring pattern L+ is not provided in the area overlapping with the DC positive potential wiring pattern P+ in plan view. This makes it possible to prevent stray capacitance from being formed between the first reference potential wiring pattern P- and the second reference potential wiring pattern L-. Also, it makes it possible to prevent stray capacitance from being formed between the DC positive potential wiring pattern P+ and the input positive potential wiring pattern L+.

[0051] 7A, 7B, and 7C, the first reference potential wiring pattern P- provided on the first wiring layer LY1 and the DC positive potential wiring pattern P+ provided on the second wiring layer LY2 overlap in a plan view. Also, the second reference potential wiring pattern L- provided on the first wiring layer LY1 and the input positive potential wiring pattern L+ provided on the second wiring layer LY2 overlap in a plan view.

[0052] As a result, the first reference potential wiring pattern P-, the second reference potential wiring pattern L-, the DC positive potential wiring pattern P+, the input positive potential wiring pattern L+, the power conversion circuit 3, and the common mode choke coil 1 function as a noise balancing circuit that balances switching noise and suppresses the generation of common mode noise, similar to the first and second embodiments.

[0053] Thereby, the switching power supply device 100 according to the third embodiment can suppress the generation of common mode noise by suppressing the external radiation of switching noise and the conduction of switching noise to the DC power supply, as in the first and second embodiments, and can suppress the level of switching noise by the noise balancing circuit. That is, the switching power supply device 100 according to the third embodiment can effectively suppress the radiation of switching noise to the DC power supply and the outside, as in the first and second embodiments, and can effectively suppress the generation of common mode noise due to noise propagation to the DC power supply.

[0054] Fig. 8 is a diagram illustrating the effect of the switching power supply device according to the embodiment. Fig. 8 illustrates the results of a conducted emission test at 70 MHz to 110 MHz. In Fig. 8, the solid line shows an example of the conducted emission test result in the configuration of embodiment 2. The dashed line shown in Fig. 8 shows an example of the conducted emission test result in a conventional example.

[0055] In the conventional example, the stray capacitance generated in the multilayer circuit board creates an outflow path for common mode noise, which causes the limit (18 dBμV) to be exceeded at around 90 MHz.

[0056] In contrast to this, in the configuration of embodiment 2, the first reference potential wiring pattern P-, the second reference potential wiring pattern L-, the DC positive potential wiring pattern P+, the input positive potential wiring pattern L+, the power conversion circuit 3, and the common mode choke coil 1 function as a noise balancing circuit, thereby canceling out the switching noise and suppressing the generation of common mode noise.

[0057] FIG. 9 is a diagram showing a noise propagation path in a configuration using a conventional common mode choke coil.

[0058] The dashed arrow paths shown in FIG. 9 indicate high-frequency (eg, 1000 MHz) noise propagation paths.

[0059] A common mode choke coil reduces common mode noise by increasing the impedance of the path through which the common mode noise flows.

[0060] In a conventional common mode choke coil that is generally used as a countermeasure against common mode noise in a low frequency band (for example, 0.15 MHz to 30 MHz), the stray capacitance CC between the input and output of the first winding 51 and the second winding 52 is large. Since the impedance of the stray capacitance CC is smaller than the impedance of the first winding 51 and the second winding 52 in a high frequency band, an outflow path for high frequency common mode noise may be formed that bypasses the first winding 51 and the second winding 52 and passes through the stray capacitance CC.

[0061] Specifically, for example, in a configuration in which the switching power supply device 100 is mounted on a vehicle, the common mode noise that flows out through the stray capacitance CC between the input and output of the first winding 51 and the second winding 52 reaches the vehicle battery through a power line such as a harness. The common mode noise that reaches the vehicle battery flows back to the DC-DC converter 3A due to the capacitive coupling (stray capacitance CX) between the reference potential (first reference potential GND1) of the vehicle (chassis) and the output point (connection point with the inductor L, see Figs. 2 and 3) of the switching circuit 3B. When the common mode noise reaches the vehicle battery, the noise flows into other vehicle devices that receive power from the vehicle battery, which may cause problems such as malfunctions of the other vehicle devices.

[0062] Hereinafter, a specific example of the common mode choke coil 1 that can reduce the stray capacitance CC between the input and output of the first winding 51 and the second winding 52 will be described. FIG. 10 is a perspective view showing an example of a common mode choke coil according to an embodiment. FIG. 11 is a plan view of the common mode choke coil seen in the third negative direction. FIG. 12 is a side view of the common mode choke coil seen in the second positive direction. FIG. 13 is a plan view of the common mode choke coil seen in the third positive direction. FIG. 14 is a side view of the common mode choke coil seen in the second negative direction. FIG. 15 is a partial cross-sectional view of the common mode choke coil including the center axis of the winding core, the location of 1.0 turn of the first winding, and the location of 1.0 turn of the second winding.

[0063] As shown in FIG. 10, the common mode choke coil 1 according to the embodiment includes a drum core 10C and a top plate 12.

[0064] The drum core 10C has a winding core portion 11, a first flange portion 20, and a second flange portion 30.

[0065] The winding core 11 is in the shape of a quadrangular prism. A cross section perpendicular to the central axis C of the winding core 11 is in the shape of a rectangle. Note that the "rectangular shape" referred to here may be any shape having four sides and being rectangular overall, and may also include a rectangular shape with chamfered corners. The material of the winding core 11 is a non-conductive material. Specifically, the material of the winding core 11 is, for example, alumina, Ni-Zn ferrite, resin, a mixture thereof, or the like.

[0066] Here, a specific axis parallel to the central axis C of the winding core 11 is defined as the first axis X. A specific axis perpendicular to the first axis X is defined as the second axis Y. In this embodiment, the second axis Y is parallel to two of the four sides of the winding core 11 when viewed in a direction along the first axis X. An axis perpendicular to both the first axis X and the second axis Y is defined as the third axis Z. In this embodiment, the third axis Z is parallel to the remaining two of the four sides of the winding core 11 when viewed in a direction along the first axis X. One of the directions along the first axis X is defined as the first positive direction X1, and the opposite direction to the first positive direction X1 is defined as the first negative direction X2. Similarly, one of the directions along the second axis Y is defined as the second positive direction Y1, and the opposite direction to the second positive direction Y1 is defined as the second negative direction Y2. Moreover, one of the directions along the third axis Z is defined as a third positive direction Z1, and the direction opposite to the third positive direction Z1 is defined as a third negative direction Z2.

[0067] As shown in Fig. 10, the first flange portion 20 is connected to a first end, which is an end in the first positive direction X1, of the winding core portion 11. The first flange portion 20 has a generally rectangular plate shape that is flattened in the direction along the first axis X. When viewed in the direction along the first axis X, each side of the first flange portion 20 is parallel to each side of the winding core portion 11. In addition, the first flange portion 20 protrudes outward relative to the winding core portion 11 in the direction along the second axis Y and the direction along the third axis Z.

[0068] Here, of the first flange portion 20, a surface facing the first positive direction X1 is referred to as a first outer end surface 22, and a surface facing the first negative direction X2 is referred to as a first inner end surface 23. Moreover, of the first flange portion 20, a surface facing the second positive direction Y1 is referred to as a first side surface 24, and a surface facing the second negative direction Y2 is referred to as a second side surface 25. Moreover, of the first flange portion 20, a surface facing the third positive direction Z1 is referred to as a first bottom surface 26, and a surface facing the third negative direction Z2 is referred to as a first top surface 27.

[0069] The first outer end surface 22 and the first inner end surface 23 are surfaces perpendicular to the central axis C. The first bottom surface 26 and the first top surface 27 are surfaces parallel to the central axis C. In addition, the first bottom surface 26 and the first top surface 27 are surfaces parallel to the mounting surface that faces the multilayer circuit board when the common mode choke coil 1 is mounted on the multilayer circuit board.

[0070] The first side surface 24 and the second side surface 25 are surfaces that are parallel to the central axis C and perpendicular to the first bottom surface 26.

[0071] The first flange 20 has a recessed portion 21. The recessed portion 21 is recessed with respect to a first bottom surface 26 of the first flange 20. The recessed portion 21 is open to both sides of the first flange 20 in the direction along the first axis X. As a result, the first bottom surface 26 of the first flange 20 is divided into two parts with the recessed portion 21 in between. The first flange 20 has a symmetrical shape in the direction along the second axis Y.

[0072] The second flange portion 30 is connected to a second end, which is the end on the first negative direction X2 side, of the winding core portion 11. The second flange portion 30 has a symmetrical shape to the first flange portion 20 in the direction along the first axis X. That is, the second flange portion 30 has a substantially rectangular plate shape.

[0073] Here, of the second flange 30, a surface facing the first negative direction X2 is referred to as a second outer end surface 32, and a surface facing the first positive direction X1 is referred to as a second inner end surface 33. Moreover, of the second flange 30, a surface facing the second positive direction Y1 is referred to as a third side surface 34, and a surface facing the second negative direction Y2 is referred to as a fourth side surface 35. Moreover, of the second flange 30, a surface facing the third positive direction Z1 is referred to as a second bottom surface 36, and a surface facing the third negative direction Z2 is referred to as a second top surface 37.

[0074] The second outer end face 32 and the second inner end face 33 are planes perpendicular to the central axis C. The second bottom face 36 and the second top face 37 are planes parallel to the central axis C. The second bottom face 36 and the second top face 37 are planes parallel to the mounting surface that faces the multilayer circuit board when the common mode choke coil 1 is mounted on the multilayer circuit board. The third side face 34 and the fourth side face 35 are planes parallel to the central axis C and perpendicular to the second bottom face 36.

[0075] The second flange portion 30 protrudes outward relative to the winding core portion 11 in the direction along the second axis Y and the direction along the third axis Z. The second flange portion 30 also has a recessed portion 31. The recessed portion 31 is recessed relative to a second bottom surface 36 of the second flange portion 30.

[0076] The first flange 20 and the second flange 30 are made of the same non-conductive material as the winding core 11. The first flange 20 and the second flange 30 are integrally molded with the winding core 11.

[0077] In this embodiment, the maximum dimension of the drum core 10C along the first axis X is 3.2 mm, the maximum dimension of the drum core 10C along the second axis Y is 2.5 mm, and the maximum dimension of the drum core 10C along the third axis Z is 2.3 mm.

[0078] The top plate 12 is a rectangular plate. The top plate 12 is flat in the direction along the third axis Z. The long side of the top plate 12 is parallel to the first axis X. The short side of the top plate 12 is parallel to the second axis Y. The top plate 12 is located on the third negative direction Z2 side with respect to the drum core 10C. The top plate 12 is connected to both the first top surface 27 of the first flange portion 20 and the second top surface 37 of the second flange portion 30. In other words, the top plate 12 is bridged between the first flange portion 20 and the second flange portion 30. The material of the top plate 12 is the same non-conductive material as that of the winding core portion 11. Note that the top plate 12 is not shown in FIG. 11 and subsequent figures.

[0079] The common mode choke coil 1 includes a first electrode 41, a second electrode 42, a third electrode 43, and a fourth electrode 44. The first electrode 41 is located on the outer surface of the first flange portion 20. Specifically, the first electrode 41 is located on the first bottom surface 26. The first electrode 41 is also located on the first bottom surface 26 on the second positive direction Y1 side with respect to the central axis C. Specifically, the first electrode 41 is located on the second positive direction Y1 side with respect to the recessed portion 21.

[0080] The second electrode 42 is located on the outer surface of the first flange portion 20. Specifically, the second electrode 42 is located on the first bottom surface 26. In addition, the second electrode 42 is located on the first bottom surface 26 on the second negative direction Y2 side with respect to the central axis C. Specifically, the second electrode 42 is located on the second negative direction Y2 side with respect to the recessed portion 21.

[0081] The third electrode 43 is located on the outer surface of the second flange portion 30. Specifically, the third electrode 43 is located on the second bottom surface 36. The third electrode 43 is also located on the second bottom surface 36 on the second positive direction Y1 side with respect to the central axis C. Specifically, the third electrode 43 is located on the second positive direction Y1 side with respect to the recessed portion 31.

[0082] The fourth electrode 44 is located on the outer surface of the second flange portion 30. Specifically, the fourth electrode 44 is located on the second bottom surface 36. Furthermore, the fourth electrode 44 is located on the second bottom surface 36 on the second negative direction Y2 side with respect to the central axis C. Specifically, the fourth electrode 44 is located on the second negative direction Y2 side with respect to the recessed portion 31.

[0083] These first electrode 41 to fourth electrode 44 have a metal layer and a plating layer. The material of the metal layer is silver. The metal layer is formed on the outer surface of the first flange portion 20 or the second flange portion 30. The plating layer is made up of three layers. The plating layer is formed by stacking copper, nickel, and tin in this order on the surface of the metal layer. In FIG. 10, the boundaries between the metal layer and the plating layer are not shown. Note that the end face of the common mode choke coil 1 on the third positive direction Z1 side is a mounting surface that faces the multilayer circuit board when the common mode choke coil 1 is mounted on the multilayer circuit board.

[0084] As shown in FIG. 10, the common mode choke coil 1 includes a first winding 51 and a second winding 52. The first winding 51 and the second winding 52 are wound around the winding core 11. Although not shown, the first winding 51 includes a copper wire and an insulating coating. The insulating coating covers the outer surface of the copper wire. The first winding 51 has a substantially circular shape in a cross section perpendicular to the direction in which the first winding 51 extends. The outer diameter of the first winding 51 is approximately 100 μm. The second winding 52 has the same configuration as the first winding 51. That is, the second winding 52 includes a copper wire and an insulating coating. The outer diameter of the second winding 52 is approximately 100 μm. In FIG. 10, the first winding 51 is colored with dots.

[0085] 11, a first line end 51A of the first winding 51 is connected to the first electrode 41. A second line end 51B of the first winding 51 is connected to the third electrode 43. The first line end 51A and the second line end 51B are connected to the corresponding electrodes by thermocompression bonding.

[0086] Here, when the first winding 51 is traced from the first wire end 51A to the second wire end 51B, the location where the first winding 51 first comes into contact with the outer circumferential surface of the winding core part 11 is defined as location A1 of 1.0 turn of the first winding 51. In this embodiment, location A1 of 1.0 turn of the first winding 51 is located on the second negative direction Y2 side and on the ridge line on the third positive direction Z1 side of the winding core part 11. In other words, location A1 of 1.0 turn of the first winding 51 is located on the second negative direction Y2 side with respect to the central axis C.

[0087] The number of turns of the first winding 51 increases by one each time the first winding 51 makes one revolution around the central axis C from the first wire end 51A to the second wire end 51B. The first winding 51 is wound around the winding core 11 so as to progress clockwise as the number of turns increases when viewed in the first negative direction X2. Therefore, for example, when viewed in the first negative direction X2, a point that progresses 36 degrees around the central axis C from the point A1 of the 1.0 turn of the first winding 51 is the point of the 1.1 turn of the first winding 51.

[0088] A first wire end 52A of the second winding 52 is connected to the second electrode 42. A second wire end 52B of the second winding 52 is connected to the fourth electrode 44. The first wire end 52A and the second wire end 52B are connected to the corresponding electrodes by thermocompression bonding.

[0089] Here, when tracing the second winding 52 from the first wire end 52A to the second wire end 52B, a point where the angular position about the central axis C first coincides with the angular position of the 1.0 turn point A1 of the first winding 51 is defined as the 1.0 turn point B1 of the second winding 52. That is, in this embodiment, the 1.0 turn point B1 of the second winding 52 is located on a straight line connecting the ridge line of the winding core 11 on the second negative direction Y2 side and the third positive direction Z1 side and the central axis C when viewed in a direction along the first axis X. Note that, in this embodiment, when tracing the second winding 52 from the first wire end 52A to the second wire end 52B, the 1.0 turn point B1 of the second winding 52 is the first to come into contact with the outer circumferential surface of the winding core 11. Note that the 1.0 turn point B1 of the second winding 52 does not have to come into contact with the outer circumferential surface of the winding core 11.

[0090] The number of turns of the second winding 52 increases by one each time the second winding 52 makes one revolution around the central axis C from the first wire end 52A to the second wire end 52B. When viewed in the first negative direction X2, the second winding 52 is wound around the winding core 11 so as to progress clockwise as the number of turns increases. That is, the second winding 52 is wound in the same direction as the first winding 51. A portion of the second winding 52 is wound around the winding core 11 from the outside relative to the first winding 51. In other words, a portion of the second winding 52 is in contact with the outer surface of the first winding 51 on the opposite side to the central axis C.

[0091] 12 to 14, first winding 51 has a 9th turn but does not have a 10th turn. That is, first winding 51 has a portion with 9.0 turns but does not have a portion with 10.0 turns. Furthermore, first winding 51 is wound directly around the outer circumferential surface of winding core 11 over substantially the entire range from portion A1 of 1.0 turn to portion A9 of 9.0 turns.

[0092] As shown in FIG. 11, the second winding 52 has a 9th turn but does not have a 10th turn. That is, the second winding 52 has a 9.0 turn portion but does not have a 10.0 turn portion. The second winding 52 is wound on the outer circumferential surface of the winding core 11 in a range from the 1.0 turn portion B1 to the middle of the second turn. The second winding 52 is in contact with the first winding 51 from the outside over substantially the entire range from the middle of the second turn to the 9.0 turn portion. The "second turn" refers to a range of 2.0 turns or more and less than 3.0 turns of the wire. The same applies to other numerical values.

[0093] The second winding 52 has a first intersection point CP1 that intersects from the outside with a portion of the first winding 51 from the first wire end 51A to the 1.0 turn point A1. The first intersection point CP1 exists in a range of 1.0 turn or more and less than 2.0 turns of the second winding 52. Specifically, the first intersection point CP1 is a point of approximately 1.8 turns of the second winding 52. The first intersection point CP1 is located on the second negative direction Y2 side with respect to the central axis C. In this embodiment, the "intersection point" refers to a point where the center line of the second winding 52 crosses the center line of the first winding 51 when viewed in a direction perpendicular to the outer circumferential surface of the winding core portion 11, i.e., in the third negative direction Z2.

[0094] 12, the 2.0 turn location B2 of the second winding 52 is adjacent to the 1.0 turn location B1 of the second winding 52 in the direction along the central axis C. The 2.0 turn location B2 of the second winding 52 is located between the 1.0 turn location A1 of the first winding 51 and the 1.0 turn location B1 of the second winding 52 in the direction along the central axis C. In other words, the 1.0 turn location A1 of the first winding 51 is separated from the 1.0 turn location B1 of the second winding 52 in the direction along the central axis C.

[0095] As shown in FIGS. 11 to 14, the range of 1.0 turn or more and less than 2.0 turns of the first winding 51 is separated from the range of 1.0 turn or more and less than 2.0 turns of the second winding 52.

[0096] Here, when tracing the second winding 52 from the first wire end 52A to the second wire end 52B, the first place where the second winding 52 first climbs onto the outside of the portion of the first winding 51 after the 1.0 turn point A1 is defined as the initial climb-up point F. The initial climb-up point F exists within a range of 2.0 turns or more and less than 3.0 turns of the second winding 52. Specifically, the initial climb-up point F is located at a position of about 2.7 turns of the second winding 52. In this embodiment, the first place where the center line of the second winding 52 first falls outside the center line of the first winding 51 is defined as the climb-up point. The "center line of the wire" is a line that passes through the geometric center of a cross section perpendicular to the extension direction of the wire. That is, in the portion of the wire wound around the winding core 11, the center line of the wire extends in the winding direction. Moreover, the above-mentioned "outside" coincides with the outside in the circumferential direction centered on the central axis C.

[0097] 11, the second winding 52 has a second intersection point CP2 that intersects from the outside with a portion of the first winding 51 from the 1.0 turn point A1 to the 2.0 turn point. The second intersection point CP2 is located within a range of 2.0 turns or more and less than 3.0 turns of the second winding 52. Specifically, the second intersection point CP2 is located at approximately 2.9 turns of the second winding 52.

[0098] 15, common mode choke coil 1 is viewed in cross section along a cross section including central axis C, 1.0 turn location A1 of first winding 51, and 1.0 turn location B1 of second winding 52. In the direction along central axis C, from the first flange 20 side to the second flange 30 side, the 1.0 turn location B1 of second winding 52, the 2.0 turn location B2 of second winding 52, the 1.0 turn location A1 of first winding 51, and the 2.0 turn location of first winding 51 are arranged in this order.

[0099] Also, on the same cross section, in the direction along the central axis C, the 3.0 turn location of the second winding 52 is located between the 2.0 turn location and the 3.0 turn location of the first winding 51. In addition, in the direction along the central axis C, the 4.0 turn location of the second winding 52 is located between the 3.0 turn location and the 4.0 turn location of the first winding 51. Similarly, the subsequent turns of the second winding 52 are wound between the first windings 51. That is, when N is an arbitrary integer equal to or greater than 3 and less than 9, in the direction along the central axis C, the N turn location of the second winding 52 is located between the (N-1) turn location and the N turn location of the first winding 51.

[0100] In the common mode choke coil 1 configured as described above, the first winding 51 has a 1.0 turn location A1 separated from the end 9.0 turns. Also, the second winding 52 has a 1.0 turn location B1 separated from the end 9.0 turns.

[0101] In addition, at least one location between the start of the first winding 51 (position A1, 1.0 turn) and the end of the first winding 51 (position 9.0 turns) is spaced 1.0 turn or more apart in the direction along the central axis C. In addition, at least one location between the start of the second winding 52 (position B1, 1.0 turn) and the end of the second winding 52 (position 9.0 turns) is spaced 1.0 turn or more apart in the direction along the central axis C.

[0102] In addition, the first winding 51 is wound in a direction along the central axis C with the second winding 52 sandwiched therebetween at least at one or more locations from the start of the winding, position A1, of 1.0 turn, to the end of the winding, position 9.0 turns. In addition, the second winding 52 is wound in a direction along the central axis C with the first winding 51 sandwiched therebetween at least at one or more locations from the start of the winding, position B1, of 1.0 turn, to the end of the winding, position 9.0 turns.

[0103] The second winding 52 is wound in a range of 2.0 turns or more and less than 3.0 turns from the start of winding, in a direction along the central axis C, with the first winding 51 in between.

[0104] This makes it possible to reduce the stray capacitance CC between the input and output of the first winding 51 and the second winding 52 of the common mode choke coil 1 compared to the conventional example, thereby making it possible to suppress the occurrence of common mode noise.

[0105] The above-described embodiments are for facilitating understanding of the present disclosure, and are not intended to limit the present disclosure. The present disclosure may be modified or improved without departing from the spirit thereof, and the present disclosure also includes equivalents thereof.

[0106] Furthermore, the present disclosure can have the following configuration as described above or instead of the above.

[0107] (1) A switching power supply device according to one aspect of the present disclosure is a switching power supply device that converts a voltage input from a DC power supply into power and supplies the converted power to a load, the switching power supply device comprising: a power conversion circuit including an input capacitor, an output capacitor, a switching element, and an inductor; a common mode choke coil provided between the DC power supply and the power conversion circuit; and a multilayer circuit board on which the power conversion circuit and the common mode choke coil are mounted, the multilayer circuit board including an insulating substrate, a first reference potential wiring pattern, a second reference potential wiring pattern, a DC positive potential wiring pattern, and an input positive potential wiring pattern, the first reference potential wiring pattern, the second reference potential wiring pattern, the DC positive potential wiring pattern, and the input positive potential wiring pattern are each provided on the insulating substrate, and the common mode choke coil is a first winding having one end connected to the low potential side of the DC power supply through a first reference potential wiring pattern and the other end connected to the low potential side of the load through a second reference potential wiring pattern, and a second winding having one end connected to the high potential side of the DC power supply through a DC positive potential wiring pattern and the other end connected to an input side of the power conversion circuit through an input positive potential wiring pattern, wherein the power conversion circuit has a portion overlapping with the second reference potential wiring pattern when viewed in a planar view from a direction perpendicular to the plane of the insulating substrate, the second reference potential wiring pattern is not provided in a region overlapping with the first reference potential wiring pattern when viewed in a planar view from a direction perpendicular to the plane of the insulating substrate, and the input positive potential wiring pattern is not provided in a region overlapping with the DC positive potential wiring pattern when viewed in a planar view from a direction perpendicular to the plane of the insulating substrate.

[0108] In this configuration, the switching noise generated by the switching operation of the switching elements is confined by the closed electric circuit, and the common mode noise that is conducted to the DC power supply is suppressed. Since the phase of the continuously generated switching noise is not constant, the noise is confined in the closed electric circuit, and is offset by each other. This effectively suppresses the radiation of the switching noise to the DC power supply and the outside, and effectively suppresses the generation of common mode noise due to noise propagation to the DC power supply.

[0109] (2) A switching power supply device according to one aspect of the present disclosure is a switching power supply device that converts a voltage input from a DC power supply into power and supplies the converted power to a load, the switching power supply device comprising: a power conversion circuit including an input capacitor, an output capacitor, a switching element, and an inductor; a common mode choke coil provided between the DC power supply and the power conversion circuit; and a multilayer circuit board on which the power conversion circuit and the common mode choke coil are mounted, the multilayer circuit board including an insulating substrate, a first reference potential wiring pattern, a second reference potential wiring pattern, a DC positive potential wiring pattern, and an input positive potential wiring pattern, the first reference potential wiring pattern, the second reference potential wiring pattern, the DC positive potential wiring pattern, and the input positive potential wiring pattern are each provided on the insulating substrate, the common mode choke coil comprising: a first winding having one end connected to a low potential side of the DC power supply via the first reference potential wiring pattern and the other end connected to a low potential side of the load via the second reference potential wiring pattern; and a second winding having one end connected to a high potential side of the DC power supply through a DC positive potential wiring pattern and the other end connected to an input side of the power conversion circuit through an input positive potential wiring pattern, wherein when viewed in a plan view from a direction perpendicular to the plane of the insulating substrate, the power conversion circuit has a portion overlapping with the second reference potential wiring pattern, when viewed in a plan view from a direction perpendicular to the plane of the insulating substrate, the second reference potential wiring pattern is not provided in a region overlapping with the first reference potential wiring pattern, when viewed in a plan view from a direction perpendicular to the plane of the insulating substrate, and the input positive potential wiring pattern is not provided in a region overlapping with the DC positive potential wiring pattern, when viewed in a plan view from a direction perpendicular to the plane of the insulating substrate, and the first reference potential wiring pattern, the second reference potential wiring pattern, the DC positive potential wiring pattern, the input positive potential wiring pattern, the power conversion circuit, and the common mode choke coil constitute a noise balancing circuit which is an electrically closed circuit, and the noise balancing circuit cancels out noise generated due to a switching operation of the switching element.

[0110] In this configuration, the switching noise generated by the switching operation of the switching elements is confined by the closed electric circuit, and the common mode noise that is conducted to the DC power supply is suppressed. Since the phase of the continuously generated switching noise is not constant, the noise is confined in the closed electric circuit, and is offset by each other. This effectively suppresses the radiation of the switching noise to the DC power supply and the outside, and effectively suppresses the generation of common mode noise due to noise propagation to the DC power supply.

[0111] (3) In the switching power supply device of (1) or (2) above, the multilayer circuit board has a first wiring layer and a second wiring layer, and when viewed in a plan view from a direction perpendicular to the plane of the insulating base material, a first reference potential wiring pattern provided in the first wiring layer and a first reference potential wiring pattern provided in the second wiring layer overlap, and when viewed in a plan view from a direction perpendicular to the plane of the insulating base material, a second reference potential wiring pattern provided in the first wiring layer and a second reference potential wiring pattern provided in the second wiring layer overlap.

[0112] In this configuration, an electric closed circuit is formed by the first reference potential wiring pattern, the second reference potential wiring pattern, the DC positive electrode potential wiring pattern, the input positive electrode potential wiring pattern, the power conversion circuit, and the common mode choke coil, which effectively suppresses the radiation of switching noise to the DC power supply and to the outside, and effectively suppresses the generation of common mode noise due to noise propagation to the DC power supply.

[0113] (4) In the switching power supply device of (1) or (2) above, the multilayer circuit board has a first wiring layer and a second wiring layer, and when viewed in a plan view from a direction perpendicular to the plane of the insulating base material, a first reference potential wiring pattern provided in the first wiring layer and a DC positive potential wiring pattern provided in the second wiring layer overlap each other, and when viewed in a plan view from a direction perpendicular to the plane of the insulating base material, a second reference potential wiring pattern provided in the first wiring layer and an input positive potential wiring pattern provided in the second wiring layer overlap each other.

[0114] In this configuration, an electric closed circuit is formed by the first reference potential wiring pattern, the second reference potential wiring pattern, the DC positive electrode potential wiring pattern, the input positive electrode potential wiring pattern, the power conversion circuit, and the common mode choke coil, which effectively suppresses the radiation of switching noise to the DC power supply and to the outside, and effectively suppresses the generation of common mode noise due to noise propagation to the DC power supply.

[0115] (5) In the switching power supply device of (1) or (2) above, the common mode choke coil, the input capacitor, the output capacitor, the switching element, and the inductor are mounted on the multilayer circuit board in the following order, aligned in approximately one direction.

[0116] With this configuration, it is possible to make it difficult for unintended stray capacitance to be formed on the multilayer circuit board.

[0117] (6) In the switching power supply device of (1) or (2) above, the common mode choke coil includes a core material around which the first winding and the second winding are wound linearly and in alignment, while rotating in one direction.

[0118] In this configuration, it is possible to reduce the stray capacitance between the input and output of the first winding and the second winding.

[0119] (7) In the switching power supply device of (6) above, the common mode choke coil has a self-resonant frequency of 30 MHz or higher.

[0120] In this configuration, common mode noise in both low and high frequency bands can be effectively suppressed.

[0121] (8) In the switching power supply device described above in (6), the core material contains alumina or Ni-Zn ferrite.

[0122] In this configuration, common mode noise in both low and high frequency bands can be effectively suppressed.

[0123] (9) In the switching power supply device of (6) above, in the common mode choke coil, the start and end of the first winding are spaced apart, and the start and end of the second winding are spaced apart.

[0124] In this configuration, it is possible to reduce the stray capacitance between the input and output of the first winding and the second winding.

[0125] (10) In the switching power supply device of (6) above, the common mode choke coil is wound at least 1.0 turn apart in a direction along the central axis of the core material at at least one location from the start to the end of the first winding, and the second winding is wound at at least one location from the start to the end of the second winding, in a direction along the central axis of the core material.

[0126] In this configuration, it is possible to reduce the stray capacitance between the input and output of the first winding and the second winding.

[0127] (11) In the switching power supply device of (6) above, the common mode choke coil is wound in a direction along the central axis of the core material, sandwiching the second winding, at at least one point from the start of winding to the end of winding of the first winding, and is wound in a direction along the central axis of the core material, sandwiching the first winding, at at least one point from the start of winding to the end of winding of the second winding.

[0128] In this configuration, it is possible to reduce the stray capacitance between the input and output of the first winding and the second winding.

[0129] (12) In the switching power supply device of (6) above, the common mode choke coil is wound in a cross section perpendicular to the bottom surface within a range of 2.0 turns or more and less than 3.0 turns from the start of winding of the second winding, and within a range of 1.0 turn or more and less than 2.0 turns from the start of winding of the first winding in a direction along the central axis of the core material.

[0130] In this configuration, it is possible to reduce the stray capacitance between the input and output of the first winding and the second winding.

[0131] (13) In any one of the switching power supplies (1) to (12) above, the input terminal of the common mode choke coil is connected to a battery.

[0132] This configuration can suppress noise from leaking into the battery.

[0133] (14) In the switching power supply device according to any one of (1) to (12) above, an input terminal of the common mode choke coil is connected to a power supply that converts commercial AC power into DC power.

[0134] With this configuration, it is possible to suppress the leakage of noise into the commercial power supply.

[0135] According to the present disclosure, it is possible to realize a switching power supply device with improved noise suppression effect. [Explanation of symbols]

[0136] 1 Common mode choke coil 2. Load 3 Power Conversion Circuit 3A DC-DC Converter 3B Switching circuit (switching regulator IC) 4 Multilayer circuit board 100 Switching power supply 311 Control circuit CC Stray capacitance CIN Input capacitor COUT Output capacitor CS Stray capacitance D Diode element L Inductor L- Second reference potential wiring pattern L+ Input positive potential wiring pattern P- 1st reference potential wiring pattern P+ DC positive potential wiring pattern Q, Q1, Q2 switching elements

Claims

1. A switching power supply device that converts a voltage input from a DC power supply into power and supplies the power to a load, a power conversion circuit including an input capacitor, an output capacitor, a switching element, and an inductor; a common mode choke coil provided between the DC power supply and the power conversion circuit; a multilayer circuit board on which the power conversion circuit and the common mode choke coil are mounted; Equipped with the multilayer circuit board includes an insulating base material, a first reference potential wiring pattern, a second reference potential wiring pattern, a DC positive potential wiring pattern, and an input positive potential wiring pattern; the first reference potential wiring pattern, the second reference potential wiring pattern, the DC positive potential wiring pattern, and the input positive potential wiring pattern are each provided on the insulating base material, The common mode choke coil comprises: a first winding having one end connected to a low potential side of the DC power supply through a first reference potential wiring pattern and having the other end connected to a low potential side of the load through a second reference potential wiring pattern; a second winding having one end connected to a high potential side of the DC power supply through a DC positive potential wiring pattern and having the other end connected to an input side of the power conversion circuit through an input positive potential wiring pattern; having the power conversion circuit has a portion that overlaps with the second reference potential wiring pattern when viewed in a plan view from a direction perpendicular to a plane of the insulating base material, the second reference potential wiring pattern is not provided in a region overlapping with the first reference potential wiring pattern when viewed in a plan view from a direction perpendicular to the plane of the insulating base material; The input positive electrode potential wiring pattern is not provided in a region overlapping with the DC positive electrode potential wiring pattern when viewed in a plan view from a direction perpendicular to the plane of the insulating base material. Switching power supply.

2. A switching power supply device that converts a voltage input from a DC power supply into power and supplies the power to a load, a power conversion circuit including an input capacitor, an output capacitor, a switching element, and an inductor; a common mode choke coil provided between the DC power supply and the power conversion circuit; a multilayer circuit board on which the power conversion circuit and the common mode choke coil are mounted; Equipped with the multilayer circuit board includes an insulating base material, a first reference potential wiring pattern, a second reference potential wiring pattern, a DC positive potential wiring pattern, and an input positive potential wiring pattern; the first reference potential wiring pattern, the second reference potential wiring pattern, the DC positive potential wiring pattern, and the input positive potential wiring pattern are each provided on the insulating base material, The common mode choke coil comprises: a first winding having one end connected to a low potential side of the DC power supply through a first reference potential wiring pattern and having the other end connected to a low potential side of the load through a second reference potential wiring pattern; a second winding having one end connected to a high potential side of the DC power supply through a DC positive potential wiring pattern and having the other end connected to an input side of the power conversion circuit through an input positive potential wiring pattern; having the power conversion circuit has a portion that overlaps with the second reference potential wiring pattern when viewed in a plan view from a direction perpendicular to a plane of the insulating base material, the second reference potential wiring pattern is not provided in a region overlapping with the first reference potential wiring pattern when viewed in a plan view from a direction perpendicular to the plane of the insulating base material; the input positive electrode potential wiring pattern is not provided in a region overlapping with the DC positive electrode potential wiring pattern when viewed in a plan view from a direction perpendicular to the plane of the insulating base material, the first reference potential wiring pattern, the second reference potential wiring pattern, the DC positive electrode potential wiring pattern, the input positive electrode potential wiring pattern, the power conversion circuit, and the common mode choke coil constitute a noise balancing circuit that is an electrically closed circuit, The noise balancing circuit cancels out noise caused by the switching operation of the switching element. Switching power supply.

3. 3. The switching power supply device according to claim 1, the multilayer circuit board has a first wiring layer and a second wiring layer; a first reference potential wiring pattern provided in the first wiring layer and a first reference potential wiring pattern provided in the second wiring layer overlap each other when viewed in a plan view from a direction perpendicular to a plane of the insulating base material; a second reference potential wiring pattern provided in the first wiring layer and a second reference potential wiring pattern provided in the second wiring layer overlap each other when viewed in a plan view from a direction perpendicular to a plane of the insulating base material; Switching power supply.

4. 3. The switching power supply device according to claim 1, the multilayer circuit board has a first wiring layer and a second wiring layer; a first reference potential wiring pattern provided in the first wiring layer and a DC positive potential wiring pattern provided in the second wiring layer overlap each other when viewed in a plan view from a direction perpendicular to a plane of the insulating base material, When viewed in a plan view from a direction perpendicular to the plane of the insulating base material, the second reference potential wiring pattern provided in the first wiring layer and the input positive potential wiring pattern provided in the second wiring layer overlap with each other. Switching power supply.

5. 3. The switching power supply device according to claim 1, the common mode choke coil, the input capacitor, the output capacitor, the switching element, and the inductor are mounted on the multilayer circuit board in such an order that the common mode choke coil, the input capacitor, the switching element, the inductor, and the output capacitor are arranged in substantially one direction. Switching power supply.

6. 3. The switching power supply device according to claim 1, The common mode choke coil includes a core material on which the first winding and the second winding are wound linearly and aligned in one direction. Switching power supply.

7. 7. The switching power supply device according to claim 6, The self-resonant frequency of the common mode choke coil is 30 MHz or more. Switching power supply.

8. 7. The switching power supply device according to claim 6, The core material includes alumina or Ni-Zn ferrite. Switching power supply.

9. 7. The switching power supply device according to claim 6, The common mode choke coil comprises: The winding start and the winding end of the first winding are spaced apart, and the winding start and the winding end of the second winding are spaced apart. Switching power supply.

10. 7. The switching power supply device according to claim 6, The common mode choke coil comprises: At least one location between the start and end of the first winding is wound with a distance of 1.0 turn or more in a direction along the central axis of the core material, and at least one location between the start and end of the second winding is wound with a distance of 1.0 turn or more in a direction along the central axis of the core material. Switching power supply.

11. 7. The switching power supply device according to claim 6, The common mode choke coil comprises: At least one or more locations from the start of winding to the end of winding of the first winding are wound in a direction along the central axis of the core material, sandwiching the second winding therebetween, and at least one or more locations from the start of winding to the end of winding of the second winding are wound in a direction along the central axis of the core material, sandwiching the first winding therebetween. Switching power supply.

12. 7. The switching power supply device according to claim 6, The common mode choke coil comprises: In a cross section perpendicular to the bottom surface, the second winding is wound in a range of 2.0 turns or more and less than 3.0 turns from the start of winding, in a direction along the central axis of the core material, with the first winding wound in a range of 1.0 turns or more and less than 2.0 turns from the start of winding. Switching power supply.

13. 3. The switching power supply device according to claim 1, The input terminal of the common mode choke coil is connected to a battery. Switching power supply.

14. 3. The switching power supply device according to claim 1, An input terminal of the common mode choke coil is connected to a power source that converts commercial AC power into DC power. Switching power supply.

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