JPH03135370A - Switching power source device - Google Patents

Abstract

PURPOSE:To miniaturize and make thin an electronic apparatus by a method wherein a data filter is miniaturized and thinned in the same degree as the thickness of a pulse transformer and a choke coil while prestage and poststage circuits are provided on a same substrate. CONSTITUTION:A data filter 11, constituting a noise filter circuit, is miniaturized and made as thin as a thin-type pulse transformer 14 or a choke coil 16 in a prestage circuit 6. All circuit components, constituting the prestage circuit 6 and a poststage circuit 7, are constituted in such a manner. By thinning the data filter 11, the height of the same may be equalized to components such as the pulse transformer 14, the choke coil 16, a first smoothing capacitor 12, a noise filter 9 and the like which are thinned so far, and accordingly, the noise filter circuit may be mounted on the same substrate. Accordingly, the whole of a switching power source device may be miniaturized and thinned. Further, the data filter 11 is constituted of a flat ferrite core 11a and a foil-type conductor 11b.

Description

DETAILED DESCRIPTION OF THE INVENTION B) Industrial Field of Application The present invention relates to a switching power supply device that is small and thin.

(b) Conventional technology Switching power supplies, as shown in Figure 18, convert commercial AC power directly into DC using a rectifying and smoothing circuit (111), and generate high-frequency signals from an oscillation circuit (121), such as 100 KHz to 50 KHz.
The switching transistor (13
1), and the switching transistor (1) is switched.
The ferrite transformer (14) is the collector load of
The output voltage is obtained from the secondary side of 1). The output voltage on the secondary side is determined by using an error amplifier (15
1), and this output is applied to a pulse width modulation circuit (161) via a photocoupler to pulse width modulate the high frequency reference pulse from the oscillator (121) to form a stabilizing feedback control system. .

Such a switching power supply can replace the conventional low frequency transformer with a small and lightweight high frequency transformer (141), greatly contributing to the reduction in size and weight of the power supply device. Such a switching power supply is described in, for example, Japanese Utility Model Publication No. 62-19107 (HO2M 37335).

However, switching power supplies are destined to generate switching noise, and this noise is a commercial AC 1! Some kind of noise countermeasure is essential to prevent noise from being superimposed on the source AC line and affecting other equipment. As a countermeasure for this,
A choke filter, which serves as a noise filter, is inserted into the power supply circuit to remove the switching frequency and its harmonics.

-The circuit of the S-like noise filter is inserted between the commercial AC power supply (101) and the rectifying and smoothing circuit (ITT> as shown in Fig. 18. L is a common mode choke coil, and C1 is a normal mode choke coil. This is a noise reduction capacitor, and C2 and C3 are both common mode and normal mode noise reduction capacitors.

A small common mode choke coil is disclosed in, for example, Japanese Patent Laid-Open No. 62-53013 (HO3H7109).

(c) Problems to be Solved by the Invention However, all conventional choke coils have had a certain degree of thickness, making them unsuitable for hybrid integrated circuits that require surface mounting. For this reason, it has been possible to reduce the size and thickness of only the post-stage circuit after the diode bridge circuit, or to integrate the post-stage circuit and part of the pre-stage circuit such as the diode bridge circuit into one package, but the noise filter Since it was not possible to store the entire switching power supply circuit in one package, there was no such thing. Therefore, since the noise filter is attached externally, there is a drawback that the demand for smaller and thinner electronic equipment cannot be fully satisfied.

(d) Means for Solving the Problems The present invention has been made in view of the above-mentioned drawbacks of the conventional art. The switching power supply device can be made smaller and thinner by making it as small and thin as the thickness of the coil (16) and by integrating all the circuit components that make up the front-stage circuit and the rear-stage circuit on the same substrate (1). It is something that will be realized.

(1) According to the present invention, by making the data filter (11) of the electronic component for a noise filter circuit thinner, other pulse transformers (14), choke coils (16), first smoothing capacitors (12), The height can be made the same as the conventionally thin components such as the noise filter (9), so the noise filter circuit can also be housed on the same board.Therefore, the entire Sui-Z Chingumi source device can be made smaller and thinner. can.

(F) Embodiment The switching source device of the present invention is as shown in FIG.
A relatively large insulating substrate (1) and a front circuit (6) and a rear circuit (7) comprising a plurality of electronic components mounted on a conductive path (2) of a desired shape formed on the insulating substrate (1).
) and a case material (19) that completely seals the front stage circuit (6) and the rear stage circuit (7).

The insulating substrate (1) (hereinafter referred to as the substrate) is 20 cm x 30 (
A relatively large substrate of -III size is used.

As the substrate (1), for example, a phenol substrate, a glass epoxy substrate, or an insulated metal substrate is used. In this embodiment, a metal aluminum substrate with excellent heat dissipation properties is used, and the surface thereof is coated with an aluminum oxide film using a well-known anodic oxidation technique.

Regarding the thickness of the substrate (1) used in this embodiment, a relatively thick substrate of 1 m to 4 m is selected and used in consideration of heat dissipation.

An insulating resin layer (not shown) such as epoxy or polyimide with a thickness of 10 to 70 μm is adhered to the main surface of the substrate (1), and a copper layer (not shown) with a thickness of 10 to 105 μm is bonded on the insulating resin layer.
(not shown) is adhered simultaneously with the insulating resin layer by means of a roller or hot press. The copper foil to be adhered onto the substrate (1) can be designed to have a constant thickness over the entire area of the substrate (1), or can be designed so that the thickness of the copper foil is varied partially. In this example, relatively large N, flow capacity and workability are considered, and the substrate (
1) It is assumed that a 70 μm copper foil is attached over the entire area.

On the surface of the copper foil provided on the main surface of the substrate (1), a conductive path of a desired shape is exposed by screen printing and masked with a resist, and a noble metal (gold, silver, platinum) plating layer is applied to the surface of the copper foil. It is marked by. Thereafter, the resist is removed and the M foil is etched using the noble metal plating layer as a mask, thereby completing the formation of the desired conductive path (2).

A plurality of electronic components are mounted on the conductive path (2), including a pre-stage circuit (6) that rectifies the AC power source, and a post-stage circuit (7) that converts the rectified power supply by the pre-stage circuit (6) into a predetermined output power source. ) are formed on the same plane.

The main electronic components that make up the front stage circuit (6) are a capacitor (8), and this capacitor (8) forms an LC resonance filter circuit to eliminate relatively low frequency noise of 10 to 500 nm in the switching section. A noise filter (9) to remove noise, and a rectifier circuit (9) to rectify AC power to DC power.
10).

Each main component of the front stage circuit (6) will be explained below.

The capacitor (8) is 16n although it is not clear from Figure 1.
uX25mmX8ml (7) It has a rectangular parallelepiped shape, and the terminal of the capacitor (8) can be connected to the conductive path (2) by soldering.

As shown in Figures 2 and 3, the noise filter (9) consists of an insulating thin plate (9a) wound spirally around an insulated conductor (9a).
9b) (9c) and is formed by arranging ferrite (9d) in a band shape near the center thereof. Its shape is a flat rectangular parallelepiped of 321111 x 50 cm x 9 ml, and the terminals (9e) provided at the four corners can be connected to the conductive path (2) by soldering.

As is well known, the rectifier circuit 10) is connected to the conductive path (2) by solder so that diode components form a bridge configuration.

Next, the main electronic components that make up the subsequent circuit (7) are a data filter (11) that removes high-frequency and low-frequency noise, including external noise that is not removed by the noise filter (9).
, a first smoothing capacitor (12) for smoothing the DC power rectified by the rectifier circuit (10), and a pulse transformer (1
4), a switching IC (13) that switches and controls the current flowing through the primary winding, and
A pulse transformer <14) with a secondary winding, a rectifier diode (15) that rectifies the output of the secondary winding that has been converted from the pulse transformer (14), and a pulse transformer (14)
A choke coil (16) that accumulates the excitation current output from and releases energy to an external load, and a second smoothing capacitor (20) that smoothes the ripple current containing ripple components via the choke coil (16). The configuration has been discussed.

Each main component of the subsequent stage circuit (7) will be explained below.

The biggest feature of this invention is the data filter (1
1), the data filter (11) will be explained in detail below.

FIG. 4 is a top view of the data filter (11), and the fifth
The figure is a side view of a flat ferrite core, and Figures 6A and B
1A and 1B are a top view and a cross-sectional view of an insulated conductor.

The data filter (11) has a flat ferrite core (11
a) and a plurality of foil-like conductors (llb>) coated with insulation.

The flat ferrite core (lla) is made of a uniform ferrite material having the same characteristics (for example, Nippon Ferrite Co., Ltd.'s GP-
7) is formed by firing. The shape is flat and rectangular, and the through hole (llc) extends perpendicularly to the thin side surface.One or more through holes (llc) are formed, but two because they are inserted into a power line. Usually, they are provided at a distance.

Therefore, the drawing shows a flat ferrite core (lla) having two through holes (llc). Referring to this drawing, the ferrite core (lla) is 46111+1
X3 QIF11

The cross section of the through hole (llc) is 13 mm x Q, 5 mm, and the distance between the two prize through holes (llc) (lie) is 8 cm. This through hole (llc) is formed by forming a groove with a depth of 0.3 cm in a 4+nm thick ferrite plate and then bonding the two ferrite plates together.

The plurality of conductors (llb) are tin-plated mild steel rectangular wires (11
e) are extended in parallel, polyester (llf)
It is formed by sandwiching and gluing. Four tin-plated mild steel rectangular wires (lie) were used for each conductor (llb), with a thickness of 0.1 ffill and a width of 1.27 TIII, and the pitch between the wires was 2.541 m1.

Therefore, the finished thickness of the conductor (llb> is polyester (l
lf), it becomes 0.4311111.

This conductor (llb) is inserted one by one into the through hole (llc), and both ends of the conductor (llb) are connected to the ferrite core (lla).
) more prominent. Furthermore, the tin-plated mild steel rectangular wire (lie) at the end of the conductor (llb) is completely exposed and is used to connect the data filter to other circuits.

Next, an equivalent circuit diagram of this data filter (11) is shown in FIG. This data filter (11) is a conductor (11b)
A conductor (llb>
and a C component formed between the ferrite core (lla). Furthermore, since this C component is inserted between the L component and the ferrite ground (FG), it functions as a common mode noise reduction capacitor. In this example, the oxide component obtained was about 2 .mu.H, and the C component obtained 5 to 25 PF.

8 and 9 show the characteristics of the data filter according to the present invention. Fig. 8 shows the frequency characteristics of the inductance of the data filter (11) specifically explained in Fig. 4, and the inductance is flat at about 2 μH up to about 3 MHz.
It has about 0.7 μH even at 10 MHz. On the other hand, FIG. 9 similarly shows the frequency characteristic of impedance, which rises steeply from about 3 MHz. As a result, this data filter (11) has a frequency of 50Hz to approximately 20MHz.
It has a filter effect over a wide band of
Switching noise of 0KHz and its harmonics can be reliably removed.

By the way, when mounting this data filter (11) on the substrate (1), the tip of the conductor (llb) and the conductive path (2
) and are fixed with solder. To explain further,
A data filter (11) is surface-mounted on the conductor (llb) so as to connect the conductive path (2) serving as a power supply line. The height of the data filter (11) is approximately the same as the height that can be achieved by the noise filter (9), first smoothing capacitor (12), pulse transformer (14), choke filter (16), etc. It is set.

The first smoothing capacitor (12) is 70mmX100mn
A thin electrolytic capacitor with a size of 6 m is used and is connected to a nearby conductive path (2) through the conductor (llb) described above.

More specifically, as shown in FIG. 10, the first smoothing capacitor (12) has a connection bin (
(not shown) is provided facing upward. An insulating plate (12b) having through-holes corresponding to connection bins can be placed on the capacitor (12a). Insulating plate (12b
) is formed with a conductive pattern (12c) for connection extending from the through hole. When the through-hole is coated with solder, the capacitor (12a) and the conductor pattern (12c) are electrically integrated, and a conductor pattern (12c) for connection to the conductive path (2) is arranged on the top side. It turns out.

As shown in FIG. 11, the switching IC (13) is mounted on a conductive path (13c) formed in a desired shape on an insulated aluminum substrate (13a) through an insulating resin Ji (13b) such as epoxy or polyimide. A plurality of circuit elements (13e) such as a power transistor (13d), a transistor, a chip resistor, and a chip capacitor are fixed to the circuit element. A power transistor (13d) and a plurality of circuit elements (13e) mounted on an aluminum substrate (13a) are coated with an epoxy resin (13f). The aluminum substrate (13a) used in this example has a size of 30m11x60+1111. Furthermore, external leads are led out from the negative peripheral end of the substrate (13a).

The switching IC (13) generates the most heat, and when mounted on the board (1), it is designed to be mounted near the center of the board (1) in consideration of heat dispersion of the heat generated. be done.

When mounting the switching IC (13) on the board (1), as shown in Figure 11, the switching IC (13) is mounted on the board (1).
(13) The conductor (13g
), fix the peripheral edge of the switching IC (13) with a Z-shaped mounting bracket (13h), and integrate the conductor (13g) and the bracket (13h) by soldering. That is, the switching IC (13) is previously formed in a separate process, and after being mounted flat on the substrate (1), the external leads of the switching IC (13) and the conductive path (2) are connected with solder.

A switching IC (
13), there is a pulse transformer (13) to be described later.
4) and choke coils (16), which generate a certain amount of heat, are arranged so that the heat generated by each component can be efficiently dissipated using the board (1).

As shown in FIGS. 12 and 13, the pulse transformer (14) is made by laminating multiple layers of metal foil (14a) formed in a bellows shape and an insulating layer (not shown) to form a ferrite core (14).
b) It is formed so as to be held in place. That is, metal foil (14a
) is for the primary winding (14a') and for the secondary winding (14a'')
The auxiliary windings (14a'') of the auxiliary power source of the switching IC (13) are formed with an insulating layer interposed therebetween, and connection terminals (14b') (14b) are formed from the respective windings.
'') (14b'') is led out and connected to a predetermined conductive path (2).

Although it is not obvious from the diagram, this pulse transformer (1
The size of 4) is a flat rectangular parallelepiped of 301 m x 601 m x 8 tlIn.

Since the rectifier diode (15) only needs to rectify the output of the pulse transformer (14), a normal electronic component diode is used.

As shown in FIGS. 14 and 15, the choke coil (16) is made by laminating multiple layers of metal foil (16a) formed in a bellows shape and an extreme R layer (not shown), similar to the pulse transformer (14). It is formed so as to be held between ferrite cores (16b). Connection terminals (1
6c) is led out and connected to a predetermined conductive path (2). Although the size of the choke coil (16) is not clear from the figure, it has a flat rectangular parallelepiped shape of 25nvnx60nynx8nwn.

The second smoothing capacitor (20) is composed of a small component like the diode (15).

By the way, on the board (1) on which the front-stage circuit (6) and the rear-stage circuit (7) are formed, there is an external connector (
17) is connected.

The external connector (17) is made of an insulating resin board such as epoxy resin.
17c) and is fixed to the substrate (1).
17a) and a connector area (17b) connected to an external circuit.
). A plurality of through holes (17d) are formed on the peripheral edge of the fixed region (17a), and conductors (17e) (17e') are formed on both sides of the through holes (17d). has been done. A plurality of connection terminals (17f) (17f') extending from each conductor (17e) (17e') are formed on the connector area (17b) where the conductors (17e) (17e') extend. ing. The connection terminal (17f) is a terminal for mixed use with AC, and the connection terminal (17f') is a terminal for frame ground (
This is the ground terminal for ground (earth).

When the external connector (17) is fixed on the board (1), the connector area (17b) is arranged so as to protrude and is fixed with solder. At this time, the solder is applied to the through hole (
17d), the board (1) and external connector (17) can be firmly fixed together in a small space. As described above, by using the external connector (17) of the present invention, connector terminals can be firmly fixed to the metal substrate (1) easily and in a small space.

On the other hand, although not shown, a lead wire for supplying output power to an external load is fixed to the opposite peripheral end of the board 1) to which the external connector (17) is fixed.

By the way, the above-mentioned substrate (1) is integrally fixed to the case material 19) via the fixing member (18).

FIG. 1B is a perspective view showing the fixing member (18) used in this embodiment. The fixing member (18) of this embodiment is an aluminum fixing member (18a) and a resin fixing member (18).
8b) can be used in combination.

The respective fixing members (18a) and (18b) are arranged at the peripheral edge of the substrate (1) to prevent warpage that occurs due to the large size of the substrate (1). At this time, the aluminum fixing member (18a) is placed on the side where the external connector (17) and the external lead wire are not completely fixed, and the resin fixing member (18b) is placed on the side where the external connector (17) and the lead wire are placed. Placed in the direction of the target.

Each fixing member (18g) arranged on each peripheral edge (
18b) is integrally fixed at each hooker portion with a screw (18c). Further, fixing through holes (18d) are formed at desired positions of each fixing member (18a) (18b), and are fixed to the substrate (1) with screws (not shown).

At this time, the conductive path (2a) for grounding is not yet formed on the board (1) on which the aluminum fixing member (18a) is placed, and when it is fixed to the board (1) with screws (not shown). It is electrically connected to the ground conductive path (2a).

On the other hand, the resin fixing member (18b) is attached to the external connector (18b).
7) and the lead wires are held between the board 1) and serve to assist in peeling off the external connector (17) and the lead wires.

Fixing members (18a) (18) are attached to the peripheral edge of the substrate (1).
After fixing b), as shown in FIG. 1C, a thin switching power supply device is completed by fixing a metal case member (19).

Case material (19) and husband k (F) fixing member (18a) (1
8b) is fixed by a metal screw (not shown).

As a result, the ground conductive path (
2a) is electrically connected to the case material (19) via the metal fixing member (18a) and has the same potential, providing a shielding effect.

Further, the heat generated on the substrate (1) is radiated by the substrate (1), and is conducted through the metal fixing member (18a) and further radiated by the case material (19). That is, the substrate (
1) and the case material (19).

In the present invention, by setting the height of all components mounted on the board (1) to 1017 flll or less, it is possible to make the power supply unit in which the front-stage circuit (6) and the rear-stage circuit (7) are mounted ultra-thin. can. Moreover, as mentioned above, it has become possible to realize a dedicated fin for heat dissipation without the need.

A specific example of a switching power supply circuit for a computer power supply using the present invention will be shown below.

FIG. 16 shows a circuit diagram of the switching regulator.

Commercial AC power supply AC first passes through a first filter circuit (Japan) consisting of a capacitor (31) and a noise filter (32), is rectified by a bridge circuit (34) consisting of diodes D, ~D4, and then Data filter (35
) and capacitors (36), (37), and (38).
is applied to the filter circuit (marked). The first filter circuit (33) can only obtain frequency characteristics with a relatively narrow bandwidth due to the conductance C of the capacitor (31) and the inductance of the noise filter (32). so that it can be removed,
Further, the second filter circuit (39) is a data filter (39).
5) allows a relatively wide frequency characteristic to be obtained, so capacitors (36), (37), and (38) provide I M
The value of each element is determined so as to remove high frequency noise of Hz to 30 MHz. In addition, the second filter circuit (39) is connected to the commercial AC power supply AC from the bridge circuit <34).
There is no problem with the circuit even if it is placed on the side. (40) is a frame ground.

The power supply voltage rectified by the bridge circuit (c) is smoothed by the smoothing capacitor (41), and the DC voltage is applied to the source of the switching transistor (43) via the primary winding side of the pulse transformer (42). has been done. The gate of the switching transistor (43) is connected to the high frequency signal of the oscillation circuit (44) (for example, 100KH2 to 500K).
The pulse of Iz is pulse-modulated and applied by a pulse width modulation circuit (45), and the switching transistor (43) is switched by this signal. (46)
(47) is a current transformer that detects the current flowing through the switching transistor (43) and protects the power supply from overload while limiting the current flowing through the transistor by a pulse width modulation circuit (45); (47) is a pulse transformer (42);
) from the flyback voltage of the switching transistor (
43) is a snubber circuit to protect the

When the switching transistor (43) is turned on, the voltage induced in the secondary winding side of the pulse transformer (42) due to the input of the DC voltage to the primary winding side of the pulse transformer (42) is applied to the rectifier diode. D.

After rectification, choke coil (48) and capacitor (4
It is smoothed by an output filter (50) consisting of 9), converted into direct current, and outputted as an output voltage OUT. When the switching transistor (43) is turned off, the energy stored in the choke coil (48) is converted into direct current by the diode D and the output filter (50), and is supplied as the output voltage OUT.

The output voltage OUT is simultaneously applied to an error detection circuit (52) for stabilizing the voltage and an overvoltage detection circuit (52) for protecting internal equipment from overvoltage. The error detection circuit (51) includes a Zener diode (5) that creates a reference voltage.
3) and resistor R1, and the photodiode of the photocoupler (
A transistor (55) for driving the transistor (54) and a resistor R,,R, for biasing the transistor (55).
When the voltage applied to the base of the transistor (55) increases and becomes higher than the reference voltage of the Zener diode (53), a current flows through the photodiode (54) to emit light. The light receiving part (56) of the photocoupler is pre-coupled with the photodiode (54), and as the amount of light emitted by the photodiode (54) increases, it becomes conductive, controlling the pulse width modulation circuit (45), and controlling the switching transistor (54). By narrowing the pulse width applied to the base of 43) and shortening the switching period, the output voltage OU can be reduced.
It works to reduce T. On the other hand, when the output voltage decreases and the base voltage of the transistor (55) decreases, the amount of light emitted by the photodiode (54) decreases, and the pulse width modulation circuit (
45> operates in the opposite manner to that described above and works to increase the output voltage OUT. In this way, the voltage is stabilized by feeding back the output voltage OUT to the pulse width modulation circuit (45) using a photocoupler. The overvoltage protection circuit (52) is
It consists of a Zener diode (57) that creates a reference voltage and a photodiode (58) of a photothyristor. When the output voltage OUT exceeds the reference voltage, the Zener diode (57) becomes conductive and causes current to flow through the photodiode (58). The photodiode (58) is made to emit light. The light receiving part (59) of the photothyristor becomes conductive due to the light emission of the photodiode (58), and the 'Fi source voltage voltage generation circuit 0
) to stop the power supply to each circuit of the switching IC (61) and stop the operation of the switching regulator circuit.

By feeding back the output voltage OUT using the photothyristor in this manner, internal equipment is protected from overvoltage when the output voltage OUT becomes an abnormal value.

By performing the above operations, a commercial AC power source can be converted to a DC power source having a predetermined output, and is used as a power supply unit section of a fun computer system.

FIG. 17 is a plan view showing the case where the switching regulator circuit shown in FIG. 16 is mounted on the board (1) of this embodiment, and the symbols of each component that can be mounted are shown in the circuit diagram of FIG. 16. It is the same as the sign.

As shown in FIG. 17, a conductive path (28) for grounding is formed on the peripheral edge and central portion of the substrate (1). The ground conductive path (2a) in the center is patterned to partition the front stage circuit (6) and the rear stage circuit (7). A substrate on which the front circuit (6) and the rear circuit (7) can be formed (
1) The upper conductive path (2) is fully connected to each component. That is, (17) is an external connector, (31) is a capacitor, (
32) is a noise filter, (34) is a rectifier circuit, (35)
) is the data filter, <41) is the smoothing capacitor, (4
6) is a current transformer, (61) is a switching I
C, <42) is a pulse transformer, (48) is a choke coil, and (49) is a capacitor.

As is clear from FIG. 17, the switching IC (61) that generates the most heat is placed approximately in the center of the board (1), and the pulse transformer (42) and choke coil (48) that generate some heat are located adjacent to it. ) are placed completely. Furthermore, a thin data filter (35) is disposed between the tR lines.

This board (1) has the first r5! The fixing member and case material shown in JB and C are used to achieve complete sealing and realize a switching power supply device.

In this embodiment, a data filter (11) is provided in the subsequent circuit (7).
are arranged, but it is also possible to arrange the data filter (11) on the front-stage circuit (6) side.

(G) Effects of the Invention As explained above, according to the present invention, the data filter (11) constituting the noise filter circuit can also be made smaller and thinner, and the front-stage circuit and rear-stage circuit of the switching regulator circuit can all be mounted on the same substrate. Switching that has become smaller and thinner through integration! It has the advantage of being able to realize a source device. Therefore, it has the advantage that it can further contribute to the miniaturization of electronic devices.

Furthermore, since all the circuit components are surface-mounted on a metal substrate with good heat dissipation properties, it also has the advantage of excellent heat dissipation properties.

[Brief explanation of the drawing]

Figures 1 to 175! J is a diagram for explaining the present invention, FIGS. 1A to 1C are perspective views showing a switching power supply device of the present invention, and FIGS. 2 and 3 each show a noise filter (9). A plan view and a side view, and FIGS. 4 and 5 are a plan view and a side view showing the data filter (11), respectively.
Figures A and 6B are a plan view and a side view respectively showing the foil conductor (llb) of the data filter (11), Figure 7 is a circuit diagram showing the equivalent circuit of the data filter (11), and Figure 8. 9th
The figures are characteristic diagrams showing the frequency characteristics of the data filter (11), Fig. 10 is a perspective view showing the first smoothing capacitor (12), Fig. 11 is a sectional view showing the switching IC (13), and Fig. 12 and Figure 13 are pulse transformers (14), respectively.
14 and 15 are respectively a plan view and a side view showing the choke coil (16), FIG. 16 is a circuit diagram of the switching regulator, and FIG. 17 is a metal board (16). FIG. 18 is a plan view showing the conductive path (2) pattern on ) and the arrangement of main components. FIG. 18 is a circuit diagram for explaining a conventional example. )...Noise filter, (11)...Data filter, (13)...Switching IC, (14)...Pulse transformer,
(16)...Choke coil.

Claims (3)

[Claims] (1) A front-stage circuit that has a rectifier circuit connected to a commercial AC power supply and a noise filter that removes noise, and a rear-stage circuit that has a switching circuit that performs a switching operation and a pulse transformer that serves as a load for the switching circuit. A switching power supply device comprising: The front-stage circuit and the rear-stage circuit are mounted on the same insulating substrate. (2) The switching power supply device according to claim 1, wherein the insulating substrate is an aluminum substrate treated with insulation. (3) The switching power supply device according to claim 1, wherein copper foil is used for the conductive path formed on the insulating substrate.