JPH05316731A - One-chip type switching power source - Google Patents

Abstract

PURPOSE:To reduce the size and rationalize a switching power source by improving high frequency characteristics of a transformer for the poser source, and eliminating the need of using a printed circuit board in the case of assembling it. CONSTITUTION:A switching power source is formed in a chip by forming a magnetic induction element such as a transformer 31, etc., for a voltage converter 30 in a thin film laminated structure, reducing its size by improving its high frequency characteristics, integrating all active elements such as a switching element 43, a voltage controller 47, etc., in a semiconductor ship 10, and assembling the converter 30 on the chip 10 in connection with the element through an arranged layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a miniature one-chip type switching power supply device in which a magnetic induction element such as a thin film laminated transformer or a reactor is mounted on a semiconductor chip.

[0002]

2. Description of the Related Art A switching power supply device widely used as a DC constant voltage power supply or a stabilized power supply for electronic devices includes so-called forward type, flyback type, chopper type, etc. In either method, the input side and the output side are coupled via a magnetic induction element or device such as a transformer or inductor, and as is well known, the input side current of this magnetic induction element is switched by a switching element such as a transistor. The DC voltage on the output side is constantly maintained at a constant value while intermittently controlling the duty ratio.

Since this switching power supply requires a rectifying diode, a smoothing capacitor, and an integrated circuit device for control in addition to the magnetic induction element and the switching element, conventionally, all of these circuit components are mounted on a printed wiring board. However, as electronic devices become larger and more complex, a small-capacity switching power supply of several to 10 W is often incorporated in each of the electronic circuits that make up the electronic device, and the electronic device should be as compact as possible for such purposes. Inexpensive switching power supplies are required. In order to meet this demand, all the semiconductor elements required for a switching power supply device including switching elements and rectifier diodes, in addition to conventional control circuits, have been developed by using the recently advanced high integration technology. It can be incorporated in a small single chip. Further, regarding the magnetic induction element and the smoothing capacitor, it is possible to halve the physical size of the magnetic induction element and the smoothing capacitor by increasing the effective reactance value thereof by increasing the switching frequency in circuit operation to several hundred kHz or more.

[0004]

As described above, semiconductor elements or active elements are all integrated in a single chip,
Moreover, rationalization of switching power supply devices has been conventionally promoted by increasing the switching frequency and downsizing passive elements such as transformers and smoothing capacitors.However, such a solution is also required in terms of performance and reliability as described below. The reality is that we are approaching the limit in terms of sex.

That is, even if each component of the device is miniaturized and the number of parts is reduced, it is still mounted on the printed wiring board, so that the size of the wiring board limits the size of the entire device. Even if the number of parts decreases, the mounting does not disappear, but rather the work becomes difficult because the parts are small, so the actual work does not change much. Moreover, since the active element and the passive element are connected through the wiring of the printed circuit board, the switching frequency is 1M.
If the frequency exceeds Hz, the circuit performance is affected by the inductance of the wiring, and the performance of the device tends to fluctuate, and the external noise picked up by the wiring tends to cause a malfunction, which lowers the reliability of the device. Therefore, it is difficult to raise the switching frequency to about 10 MHz.

Another problem is that when the switching frequency becomes 1 MHz or higher, the frequency characteristic of the magnetic induction element deteriorates and the inductance value becomes saturated. That is, in the frequency region near 100 kHz, an output proportional to the square root of the frequency can be taken out from the magnetic induction element of a fixed size.
And a reactance value proportional to the frequency is obtained,
In the high frequency region above MHZ, the high frequency loss of the magnetic circuit of the magnetic induction element increases, and the influence of the distributed capacitance inside the element also increases, so the frequency characteristic of the inductance value gradually decreases, and the product of it and the angular frequency. Since the reactance value is saturated in a high frequency region of 10 MHz or higher and hardly increases, it becomes impossible to miniaturize the magnetic induction element below a certain limit.

Still another problem is that the high frequency loss of the switching element increases as the switching frequency increases. For example, the result of analyzing the loss when operating a flyback type switching power supply device at a switching frequency of 1 MHz shows that
% Switching elements, 20% magnetic induction elements, remaining 45
% Occurs in each of the other parts, and the loss of the switching element is the maximum, and this becomes a bottleneck as the frequency is increased. It is an object of the present invention to provide a switching power supply device that overcomes the above-mentioned conventional limitations or bottleneck, can be further downsized, and has the highest conversion efficiency.

[0008]

According to the present invention, the object is to provide a voltage conversion section comprising a magnetic induction element having a structure in which thin films are laminated, a switching element for interrupting an input side current of the voltage conversion section, and a voltage conversion section. A voltage control unit for controlling the on / off of the switching element so as to control the output side voltage of the unit to a desired value constantly, and the active element including the switching element and the circuit element of the voltage control unit is incorporated in a single semiconductor chip, This is achieved by a one-chip type switching power supply device in which a wiring layer interconnecting active elements and a voltage converter connected to the active layer are sequentially laminated on an insulating film on the semiconductor chip.

Although any of the above-mentioned forward type, flyback type, chopper type and the like can be adopted as the circuit system of the switching power supply device having the above-mentioned configuration, a flyback type transformer is used as the magnetic induction element of the voltage conversion section. Is particularly advantageous in simplifying the overall configuration while maintaining high constant voltage performance of the output side voltage. It is advantageous to use an insulated gate control type element such as a field effect transistor or an insulated gate bipolar transistor for the switching element in order to insulate between the input and output, and thereby the switching frequency that interrupts the input side current of the voltage conversion unit. Is more than 1 MHz, preferably about 10 MHz or more, which is particularly advantageous for downsizing the device. When a capacitor is incorporated for smoothing the output voltage, it is preferable to use an aluminum film or an insulating film for wiring to form it in the wiring layer.

Further, in order to reduce the high frequency loss of the switching element and increase the conversion efficiency of the device, at least the input side of the voltage converter is divided into a plurality of parts, and the input side current flowing through each divided input part is controlled by the voltage controller. It is advantageous to make individual connections by switching elements that are commonly controlled by. In this case, the magnetic induction element of the voltage conversion unit may be single, and only the input side thereof may be divided into a plurality of pieces, but rather, a plurality of magnetic induction elements may be provided and the input side currents thereof may be individually separated by the switching elements. It is advantageous to connect the output side of a plurality of magnetic induction elements in series and take out the output side voltage in order to strengthen the magnetic coupling between the input side and the output side.

When a plurality of magnetic induction elements are used as described above, it is necessary to reduce the size of each element as much as possible. For this purpose, the thin film conductors of the coils on the input side and the output side are arranged in the vertical direction. Layers, usually divided into two layers and connecting them between layers reduces the area of each magnetic induction element,
To reduce the number of crossings between thin film conductors and to increase the magnetic coupling coefficient between the input side coil and the output side coil where the number of turns of each magnetic induction element is significantly different when the output sides of multiple magnetic induction elements are connected in series. It is advantageous.

The pattern of the thin film conductor for the transformer or the coil of the reactor as the magnetic induction element may be formed in a spiral shape or a zigzag shape in order to improve the area efficiency, and the latter may reduce the high frequency loss of the magnetic circuit. Among the advantages, the former is the simplest in structure and is advantageous in enhancing the magnetic coupling between the input side coil and the output side coil in the case of a transformer to increase the output that can be taken out from a transformer of a certain size. It is preferable to use a magnetic thin film of a ferromagnetic metal having soft magnetism for the iron core of the magnetic induction element, and a thin film conductor for a coil is sandwiched from both sides by this magnetic thin film to form the magnetic induction element into a so-called outer iron structure. Is advantageous in reducing the problem of magnetic leakage. In addition, amorphous magnetic metal is used for this magnetic thin film, and cutting a number of narrow slits in the direction orthogonal to the coil thin film conductor reduces the high frequency loss of the magnetic circuit and reduces the inductance value of the magnetic induction element. It is particularly advantageous for improving the high frequency characteristics of.

[0013]

The present invention integrates all active elements including switching elements in a single semiconductor chip, and
By adopting a thin film laminated structure for the magnetic induction element of the voltage conversion unit, which is indispensable for the switching power supply unit, the switching frequency has been increased from the conventional limit, and the size has been reduced to the level that it can be mounted on an integrated circuit chip. By mounting the voltage conversion part of the device on the semiconductor chip of the integrated circuit via the wiring layer and integrating it into a one-chip type device, the switching power supply device can be downsized while eliminating the conventional problems related to the printed wiring board, and It enables the drastic rationalization by eliminating the need for mounting and assembling the device.

In addition to such downsizing, it is necessary to suppress high frequency loss in the switching power supply device to maximize the conversion efficiency, and the loss of the switching element is the largest among the constituent parts of the device as described above. The input side current of each switching element is divided into multiple parts and the input side currents flowing in each divided input part are individually interrupted to the switching element, thereby lowering the current rating of the switching element and increasing its operating speed to reduce switching loss. Is particularly advantageous.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration circuit diagram showing a configuration of a switching power supply device of the present invention for a main circuit system, FIG. 2 is a partial cross-sectional perspective view illustrating the one-chip structure, and FIG. 3 is a magnetic induction element of a voltage conversion unit. FIG. 4 is a partially cut-away top view illustrating the thin film laminated structure of FIG. 2 for a high frequency transformer and a cross-sectional view of the main part thereof. FIG. FIG. 5 is a top view of a chip showing an arrangement example of magnetic induction elements and the like corresponding to the embodiment of FIG. 4, and FIG. 6 is a pattern example in which upper and lower two layers of a thin film conductor for a coil of each magnetic induction element are divided. It is a top view shown.

1 (a) shows a flyback type switching circuit, FIG. 1 (b) shows a forward type switching circuit, and FIG. 1 (c) shows a chopper type switching power supply circuit. First, the circuit configuration will be briefly described. In the circuit of FIG. 1 (a), the magnetic induction element of the voltage conversion unit 30 shown on the upper side of the drawing is a flyback type transformer 31, and in the present invention, the iron core or the magnetic circuit 32 has a magnetic thin film and its primary coil 34. Conductor thin films are used for the secondary coil 35 and the secondary coil 35, respectively. In the example shown in the figure, an AC voltage is received at the input terminal Ti, a DC voltage smoothed by the rectifier circuit 41 and smoothed by the capacitor 42 is applied to the primary coil 34 of the transformer 31, and the current flowing through it is switched as usual. The AC voltage generated by the secondary coil 35 of the transformer 31 is rectified by the rectifier diode 44 while being controlled intermittently by the element 43, smoothed by the capacitor 46, and output to the load as a stabilized DC voltage from the output terminal To. It is supposed to do.

In the present invention, it is preferable to use an insulated gate control type semiconductor element such as a field effect transistor or an insulated gate bipolar transistor as the switching element 43, and the gate is controlled by the voltage control section 47. Switch operation. The voltage control unit 47 includes an oscillation circuit that determines this switching frequency as usual, and in the present invention, this frequency is set to at least 1 MHz or higher, preferably 10 MHz or higher. Also,
This voltage control unit 47 inputs the actual value of the output voltage detected by the voltage detection circuit 48 consisting of a pair of resistors in the example of the figure, and switches the switching element 45 so as to keep it at a desired value as usual.
For example, a CMOS integrated circuit.

In the forward type switching power supply circuit shown in FIG. 1 (b), a normal transformer is used as the transformer 31, and the DC voltage obtained by rectifying the secondary AC voltage with the diode 44 is used as the reactor.
It is smoothed by 37 and capacitor 46 and then output from output terminal To. In this case, the diode 45 is connected for so-called freewheeling. In the chopper type power supply circuit of FIG. 1 (c), the reactor 37 is used as the magnetic induction element of the voltage conversion unit 30.
, The DC current flowing through it is interrupted by the switching element 43 to control the internal voltage drop thereof, and the DC voltage stabilized by the capacitor 46 is output from the output terminal To. In this case as well, the diode 45 is connected for freewheeling.

In the above circuit system, the chopper type shown in FIG. 1 (c) has the simplest circuit structure and is advantageous for making the switching power supply device into one chip, but in terms of the performance of making the output voltage constant. Although it is slightly inferior, the forward type shown in Fig. 1 (b), on the contrary, is the best in terms of performance.
In addition to 31, the reactor 37 is required, so it is slightly disadvantageous for one chip. The flyback type shown in FIG. 1 (a) is also excellent in performance, and the reactance of the secondary coil 35 of the transformer 31 is used for smoothing the output voltage, so that the forward type reactor 37 can be omitted. 30 is easy and it is also advantageous for one chip. From this point, the flyback type switching power supply device of FIG. 1 (a) is most advantageous in implementing the present invention.

In the present invention, when the switching power supply device of any of the above-mentioned circuit systems is integrated into one chip, all the active elements including the switching element 43 and the voltage control section 47 are shown surrounded by a chain line for the sake of convenience. Semiconductor chip
In the figure, which is integrated on the surface of this chip and is arranged on the surface of this chip, the active elements are connected to each other in the wiring layer 20 shown by the large frame of the dashed-dotted line. Equipped with an inductive element. It is not necessary to incorporate the rectifier circuit 41 and the capacitor 42 in the figure into the switching power supply device, and instead, a DC voltage may be supplied to the input terminal Ti, and in some cases, for stabilizing the output terminal To side. The capacitor 46 can also be connected to the load side of the power supply.
When the capacitors 42 and 46 are incorporated in the power supply device, it is advantageous to form them in the wiring layer 20 by utilizing the aluminum film or insulating film necessary for the same.

FIG. 2 shows an example of a one-chip structure of the switching power supply device according to the present invention for a flyback type corresponding to FIG. 1 (a). Integrated circuit semiconductor chip as shown
It has a structure in which a wiring layer 20 and a voltage conversion unit 30 are sequentially stacked on the wiring layer 10. The semiconductor chip 10 of the illustrated embodiment utilizes a so-called substrate-bonded wafer, which is dielectrically isolated, in order to prevent mutual interference in operation between the active devices formed therein. As is well known, this wafer is formed by bonding a pair of upper and lower semiconductor substrates 1 and 2 to each other with a silicon oxide film 3 sandwiched therebetween, and digging a groove from the surface of the semiconductor substrate 2 to reach the silicon oxide film 3. And then dividing it into a plurality of semiconductor regions, covering the groove surface with a dielectric film 4 and filling the groove with polycrystalline silicon 5, the active element is provided in each semiconductor region in which the substrate 2 is dielectrically separated. Or an active element group is built.

FIG. 2 shows a switching element 43 as a typical example among a large number of active elements built in the semiconductor chip 10.
The rectifier diode 44 and the n- and p-channel field effect transistors 47a and 47b of the voltage controller 47 are shown. The switching element 43 for the main circuit is a vertical field effect transistor, and the rectifier diode 44 also has a vertical structure. An interlayer insulating film 11 made of phosphosilicate glass or the like is usually deposited on the surface of the chip 10 so as to cover the polycrystalline silicon gate from above.

The wiring layer 20 is usually of a multi-layered wiring structure, and is made of aluminum or the like, which is in conductive contact with the semiconductor layer of the active element in the window opened in the interlayer insulating film 11 to connect the elements to each other. This is a laminated structure of a multilayer wiring film (21) made of metal and an insulating film (22) made of a silicon oxide film or the like arranged between the layers. In this embodiment, a capacitor 46 for stabilizing the output voltage is built in a part of the wiring layer 20 which is slightly bulged upward as shown in the figure, and the same aluminum film as the wiring film 21 is used. It is composed of a plurality of layers of electrode films 23 and a thin dielectric film 24 made of silicon oxide or the like sandwiched between them, and is connected to the rectifying diode 44 and the like in the semiconductor chip 10 via the wiring film 21. Furthermore, the uppermost layer of this wiring layer 20 is an insulating film.
Covered by 25.

In this example, which is a magnetic induction element for the voltage conversion unit 30, a flyback type transformer 31 is formed on the insulating layer 25 of the wiring layer 20, and its concrete structure is shown in FIG. As will be described later, in FIG. 2, only the outer contour is simply shown. The surface of the wiring layer 20 and the voltage conversion portion 30 is finally covered with a protective film 50 made of silicon nitride or the like, and aluminum of the wiring film 21 is exposed in an opening 51 opened at an appropriate portion thereof, as shown in FIG. Use as input / output terminal Ti and connection pads for To.

FIG. 3 showing an example of the structure of the transformer 31 is shown in FIG.
The top view is shown in (a), and the cross-sectional view taken along the line XX is shown in (b). The transformer 31 of this embodiment is shown in FIG.
As shown in (b), the magnetic thin film 32 on the lower side sequentially laminated on the insulating film 25 of the wiring layer 20 shown in a simplified form, the insulating film 33, and the primary and secondary layers made of thin film conductors. With the next coil 34
The upper and lower magnetic thin films 32, 35, the insulating film 36, and the upper and lower magnetic thin films 32 form a closed magnetic circuit that surrounds the coils 34 and 35 from the outside, which is a so-called outer iron structure. Figure 3
As shown in (a), in this embodiment, the primary coil 34 and the secondary coil 35 are formed in a spiral shape, and the terminals 34a,
34b, 35a and 35b are connected to the switching element 43 and the diode 44 via the aluminum wiring film 21 of FIG. In the illustrated example, the number of turns of the primary coil 34 and the number of turns of the secondary coil 35 are 6 and 2.5, respectively. Therefore, the turn ratio is 2.4, and the two are connected so that the winding directions are opposite.

The coils 34 and 35 are made of a highly conductive metal such as aluminum, copper, silver, etc., by a sputtering method or a vapor deposition method.
It consists of a thin film conductor with a film thickness of several tens of μm, and this is photoetched using semiconductor manufacturing technology.
A spiral pattern with a width of several tens to 100 μm as shown in (a) is formed. The magnetic thin film 32 is arranged so as to surround the spiral coils 34 and 35 from above and below, as shown in FIG.
For convenience of illustration, only a part thereof is shown. The magnetic thin film 32 is a thin film having a thickness of 10 to several tens of μm, which is formed by sputtering a ferromagnetic metal having soft magnetism such as permalloy, preferably in an amorphous state,
To reduce the high frequency loss as much as possible, slit as shown
32a is cut in a direction orthogonal to each turn of coils 34 and 35. The interval between the slits 32a is 10 to several tens of μm.

As described above, according to the present invention, since the magnetic induction element is composed of the laminated structure of the magnetic thin film and the conductive thin film, the internal high frequency loss is reduced, and the frequency characteristic in the high frequency region where the switching frequency is 1 MHz or higher is conventionally obtained. Better than 10M
It is possible to have a high inductance value of about several μH even at a frequency of Hz. Therefore, in the present invention, the switching frequency is increased as compared with the conventional one, and the size of the magnetic induction element is several to 20 mm.
It can be reduced to a size that can be easily mounted on the corner semiconductor chip 10, and the overall thickness of the laminated structure is 100 μm because it is a thin film structure.
Can be paid below.

As shown in FIG. 2, the semiconductor chip 10 as well as the voltage converter 30 including the thin film transformer 31 is mounted or incorporated on the wiring layer 20 as shown in FIG. After covering with, each chip is separated. As described above, in the present invention, all the one-chip type switching power supply devices can be manufactured by using the semiconductor process technology. The switching power supply device of the present invention is a very small one-chip type, and since the voltage conversion unit 30 has already been incorporated, no connection via a printed wiring board is conventionally required at all, for example, in the form of chip mounting. It can be used immediately by simply incorporating it into an electronic device or an electronic circuit and connecting to it via the aforementioned connection pad.

FIG. 4 shows an embodiment of the present invention, which is advantageous in reducing the loss in the switching element 43, by a circuit of a flyback type switching power supply device corresponding to FIG. 1 (a). In this aspect of the present invention, only the input side of the voltage conversion unit 30 is divided into a plurality of pieces, and the input side current flowing through each divided input portion is individually interrupted by the switching element 43. For this purpose, the voltage converter 30 may be composed of a single transformer having a plurality of input coils, but in the embodiment of FIG. 4, the transformer 31 is used as a magnetic induction element for the voltage converter 30. Multiple,
For example, about 10 pieces are provided, and as shown in the figure, those primary coils 34
The current flowing in each of them is individually interrupted by a dedicated switching element 43.

Further, as in the case of FIG. 1 (a), an AC voltage received at the input terminal Ti is rectified by the rectifier circuit 41 and a DC voltage smoothed by the capacitor 42 is applied to the plurality of primary coils 34, The voltage control unit 47 commonly applies a switching command SS to the plurality of switching elements 43 to cause the currents flowing therethrough to be interrupted all at once, and the secondary coils 35 of the transformer 31 are all connected in series. The secondary side AC voltage is rectified by the rectifying diode 44, stabilized by the capacitor 46, and then taken out from the output terminal To as a DC output voltage, as in the case of FIG. 1A.

In the embodiment of FIG. 4, the switching element 43
Since the current to be intermittently reduced by about one digit, not only the loss of each switching element 43 is reduced in proportion to this current value, but also the size of the element 43 can be reduced according to the current value, so its operating speed is reduced. It is possible to reduce the loss associated with this on / off operation, particularly the so-called turn-off loss that is generated almost in proportion to the volume in which the depletion layer in the semiconductor region spreads, more than in proportion to the current value. This loss reduction effect is advantageously exerted in the frequency region where the switching frequency of the element 43 is 1 MHz or more, and is particularly remarkable in the high frequency region of 10 MHz or higher approaching the limit frequency at which the small transistor for the element 43 can operate. .. As can be seen, the embodiment of FIG. 4 is advantageous in increasing the switching frequency to 1 MHz or higher in order to make the switching power supply small enough to be easily integrated into one chip.

As the switching frequency is increased, the loss of the drive circuit for the switching element 43 at the output stage in the voltage control section 47 tends to increase, and at 1 MHz, the loss of the drive circuit is within the switching power supply. 15 of total loss
%, But this ratio increases at higher frequencies. This is because normally a CMOS inverter circuit is used in the drive circuit to alternately turn on and off a pair of transistors. During this operation, both transistors are both turned on and there is a short-circuit current flow time. This is because the response becomes insufficient and the short-circuit time increases and the short-circuit loss increases. Therefore, at a frequency of several MHz or more, as a modification of the embodiment of FIG. 4, a driving circuit is attached to each switching element 43 or every two to three elements, and the size of the transistor for the inverter is reduced to improve the operating speed. It is advantageous to reduce short-circuit losses in the drive circuit by increasing.

FIG. 5 shows an arrangement example of the voltage conversion unit 30 and the like on the chip 10 corresponding to the circuit of FIG. In the example shown in the figure, the voltage conversion unit 30 is formed by arranging nine transformers 31 each having a size of 2 to 4 mm square in a square shape, and an input side capacitor 42 and an output side capacitor 46 are mounted on the sides thereof. Further, a terminal region 60 for the input terminal Ti and the output terminal To is set on the right peripheral portion of the chip 10. As can be seen from this, when the voltage converter 30 is composed of a plurality of transformers 31 as shown in FIG. 4, it is necessary to downsize each transformer 31. An advantageous mode for this is shown in FIG. An example of a pattern is shown.

In the example of FIG. 6, the primary coil 34 of the transformer 31 is
The secondary coil 35 and the secondary coil 35 are spirally formed as in the case of FIG. 3, but in order to reduce the area, the thin film conductors are divided into upper and lower two layers, and both layers are laminated and laminated. Connect to each other. FIG. 6 (a) shows the pattern of the lower layer and FIG. 6 (b) shows the pattern of the thin layer conductor on the upper layer, respectively, and the portions corresponding to FIG. Since it is necessary to make the number of turns of the primary coil 34 and the secondary coil 35 of each transformer 31 considerably different as seen from FIG. 4, in the example of FIG. 6, the thin film conductor for the secondary coil 35 is used for the primary coil 34. The thin film conductor is arranged between the inner diameter side turn and the outer diameter side turn to strengthen the magnetic coupling between both coils.

As shown in the figure, the primary coil 34 is formed so that the thin film conductor on the lower layer side in FIG. 6 (a) is overlapped with the thin film conductor on the upper layer side in FIG. 6 (b). A membrane is provided. The primary coil 34 starts from one terminal 34a on the lower layer side of FIG.
It moves to the upper layer side of (b) and ends at the other terminal 34b, and the number of turns is 9.5 times in the example of the figure. Also in the secondary coil 35, the thin film conductor on the upper layer side overlaps the thin film conductor on the lower layer side, starts from one terminal 35a on the upper layer side, moves to the lower layer side via the connecting terminal 35c, and ends at the other terminal 35b. The number of turns is 1.5 in the example shown. Therefore, the winding ratio of both coils 34 and 35 is 6.3 in this example, but since the transformer 31 in FIG. 4 is a flyback type, the secondary coil 35 is connected so that the winding direction is opposite to that of the primary coil 34. To be done.

Both coils 34 and 35 formed as described above are sandwiched from both sides by a magnetic thin film 32, a part of which is shown in a thin line in FIG. 6 (a), as in the case of FIG. 3 above. ..
In order to reduce the high frequency loss of this magnetic circuit, a narrow slit 32a is formed in the magnetic thin film 32 as in the case of FIG.
It is better to cut in the direction orthogonal to the thin film conductors of 35 and 35. By arranging the thin film conductors of both coils 34 and 35 in two layers as shown in FIG. 6, the area of the transformer 31 can be reduced, and the thin film conductors of the lower layer side and the upper layer side can be superposed. Intersections between can be eliminated. Further, by disposing the thin-film conductor of the secondary coil 35 having the smaller number of turns between the inner diameter side and the outer diameter side of the thin-film conductor of the primary coil 34, as described above, between the coils 34 and 35. The magnetic coupling can be strengthened to increase the power output from the transformer 31.

The switching power supply device according to the present invention described above is particularly suitable for a mass-produced stabilized power supply device having a relatively small capacity of about 1 to 10 W, and by implementing the present invention, the switching frequency is 1 to 10 MHz and the chip size is several. ~ 20mm square,
It is possible to inexpensively provide a miniature one-chip switching power supply device that has a thickness of 1 mm or less and a conversion efficiency of 70 to 80% that can be easily incorporated into various electronic circuits. It is expected that further improvements in the future will further increase the switching frequency and enable further miniaturization.

[0038]

As described above, according to the present invention, the magnetic induction element of the voltage conversion section has a thin film structure, and the switching element for intermittently controlling the input side current and the output side voltage are controlled intermittently. All active elements including a voltage control section are integrated into a single semiconductor chip, and a wiring layer for interconnecting active elements and a voltage conversion section are sequentially laminated on the chip to form a one-chip type switching power supply device. As a result, the following effects can be obtained.

(A) The magnetic induction element of the voltage converter, which is indispensable for the switching power supply device, has a thin film structure to reduce high frequency loss, so that the frequency characteristic of the inductance value can be improved and the size can be mounted on the semiconductor chip. Since the size can be reduced to a certain extent, the switching power supply device can be made much smaller than the conventional one by using one chip. (b) Since the voltage converter is mounted on a semiconductor chip with active devices integrated via a wiring layer, it is possible to eliminate all problems such as performance variations and malfunctions due to external noise based on conventional printed wiring boards. It is possible to provide a highly reliable switching power supply device that has been eliminated and has good performance.

(C) Since the switching power supply device can be manufactured using all semiconductor process technology without the need of assembling the device and mounting the parts, mass production thereof is facilitated and the manufacturing cost is greatly reduced by rationalizing the manufacturing process. it can. (d) Since the switching frequency can be increased from the conventional limit by thinning the magnetic induction element, even when incorporating a capacitor into a switching power supply device, it is possible to reduce the capacitance value and use a very small size. it can.

(E) In the mode in which the input side of the voltage conversion section is not divided or a plurality of magnetic induction elements are provided and the input side current is individually interrupted by the switching elements, the operation is performed by reducing the current flowing in each switching element. The conversion efficiency can be improved by increasing the speed and reducing the loss associated with the on / off operation, and by further increasing the switching frequency, the switching power supply device can be further downsized.

[Brief description of drawings]

FIG. 1 shows a circuit configuration example of a one-chip type switching power supply device of the present invention with respect to some circuit systems. FIG. 1 (a) is a flyback type, FIG. 1 (b) is a forward type, and FIG. It is a configuration circuit diagram of a chopper type switching power supply device.

FIG. 2 is a partial cross-sectional perspective view showing an example of a one-chip structure of a switching power supply device of the present invention for a flyback type.

3A and 3B show an example of a thin film laminated structure of a magnetic induction element of a voltage conversion unit for a flyback type transformer, FIG. 3A is a partially cutaway top view thereof, and FIG. 3B is a cross-sectional view of its main part. And
The figure (b) is equivalent to the XX arrow cross section of the figure (a).

FIG. 4 is a circuit diagram of a different embodiment of the present invention in which a plurality of switching elements and magnetic induction elements of a voltage conversion unit are provided.

5 is a top view of a chip showing an arrangement example of a plurality of magnetic induction elements and their related portions corresponding to the embodiment of FIG. 4. FIG.

FIG. 6 is a schematic diagram showing the coil of the magnetic induction element of the embodiment of FIG.
The figure shows an example of a thin-film conductor pattern when it is divided into layers.
(a) is a top view of the thin film conductor on the lower layer side, and (d) is a top view of the thin film conductor on the upper layer side.

[Explanation of symbols]

 10 Semiconductor chip 20 Wiring layer 30 Voltage converter 31 Transformer as magnetic induction element 32 Magnetic thin film 32a Slit of magnetic thin film 34 Primary coil or thin film conductor for it 35 Secondary coil or thin film conductor for it 43 Switching element 46 Output Voltage stabilizing capacitor 47 Voltage control unit

Claims (5)

[Claims] 1. A voltage conversion unit composed of a thin film magnetic induction element, a switching element for connecting and disconnecting an input side current of the voltage conversion unit, and a switching for controlling an output side voltage of the voltage conversion unit to a desired value. A voltage control section for controlling the on / off of the element, an active element including a switching element and a circuit element of the voltage control section is incorporated in a single semiconductor chip, and a wiring layer for interconnecting the active element on the semiconductor chip and A one-chip type switching power supply device characterized in that voltage conversion units connected thereto are sequentially laminated through an insulating film. 2. The one-chip type switching power supply device according to claim 1, wherein a switching frequency for interrupting an input side current of the voltage conversion section by a switching element is 1 MHz or higher. 3. The one-chip type switching power supply device according to claim 1, wherein a flyback transformer is used as the magnetic induction element of the voltage conversion unit. 4. The device according to claim 1, wherein at least an input side of the voltage conversion section is divided into a plurality of pieces, and an input side current flowing through each divided input section is individually controlled by a switching element controlled by a voltage control section. A one-chip type switching power supply device characterized by being intermittently connected. 5. The device according to claim 4, wherein a plurality of magnetic induction elements of the voltage conversion unit are provided, the input side currents thereof are individually interrupted by switching elements, and the output side is connected in series to output. A one-chip type switching power supply device characterized by extracting the side voltage.