JPH0469059A - Switching power supply device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial Application Field The present invention relates to a converter-type switching power supply device in which input and output are insulated. and a switching power supply device each mounting a secondary side circuit.

(b) Prior Art FIG. 6 shows a flyback type switching power supply circuit.

In the illustrated switching power supply circuit, the primary winding and the secondary winding have opposite polarities, and the human power VIN and the output V. A switching transistor or power M that controls the current flowing from the input VIN to the transformer T.
A switching element Q such as an OSFET, a PWM circuit (60) that sends a pulse with a constant frequency of several tens of KHz and whose duty is changed by a feedback signal to the control electrode of the switching element Q (60), and leakage inductance of a transformer T. A snubber circuit (66) for dissipating the energy accumulated in the switching element Q, a current detector (64) for monitoring the current of the switching element Q and providing overcurrent protection, and a temperature detector (64) for preventing thermal runaway in the power supply circuit. 62), a diode D3, a capacitor C2, and an output ■ which rectify and smooth the output voltage of the transformer T, respectively. It is composed of a voltage detector (68) that performs constant voltage control and overvoltage control of U□, a photocoupler (70) that insulates back the output of this voltage detector (68), and the like.

Next, the operation of the switching power supply circuit configured as described above will be explained.

When the output pulse of the PWM circuit (60) becomes high level and the switching element Q is turned on, a closed circuit of the primary winding of the lance T and the switching element Q is formed, and a voltage of 1 is applied to the primary winding of the transformer T. A current that increases exponentially flows. At this time, the secondary winding output of the transformer T is blocked by the diode D3, so no power is transmitted through the transformer T, and all the energy supplied to the primary winding is stored in the transformer T. And PWM circuit (
When the output pulse of 60) becomes low level and the switching element Q is turned off, a back electromotive force is generated in the primary winding, and the secondary winding output based on this back electromotive force is sent to the capacitor C2 via the diode FD3. The output voltage is V. It becomes U□.

The switching power supply circuit that performs the above operations is highly efficient, so if it has a relatively small capacity, it is possible to create a hybrid integrated circuit on an insulating substrate such as ceramics. Suitable as a power source for equipment. However, since insulating substrates such as ceramics generally have low thermal conductivity, there is a problem that it is not possible to form a large-capacity switching power supply circuit that generates a large amount of heat into a hybrid integrated circuit.

(c) Problems to be solved by the invention On the other hand, when converting a switching power supply circuit into a hybrid integrated circuit by using an insulated metal substrate as the substrate, the problem of heat dissipation is solved, but due to safety standards, switching power supply Since it is said that the primary side circuit and the secondary side circuit of the circuit should not be formed on a single metal substrate, there is a problem that the manufacturing process becomes complicated.

In addition, since switching power supply devices in particular have a large number of needs in terms of current capacity, input/output voltage, power capacity, etc., the burden of development to meet some of these needs becomes heavy.

Therefore, the present invention provides a switching structure that can simplify the circuit pattern formation process, element mounting process, etc. to the same level as using a single board, and can quickly respond to the needs of a large number of users without increasing the development burden. The purpose is to capture and provide a power supply.

(Means for Solving the Gradient Problem) The present invention has been made in view of the above problem, and is a method of mounting the primary side circuit and the secondary side circuit of a switching power supply circuit on first and second insulated metal substrates. By coupling the first and second insulated metal substrates with a photocoupler that insulates and returns voltage signals and overvoltage signals from the secondary circuit to the primary circuit, the primary circuit of the switching power supply circuit and the This solves the problem of the insulation distance between the next-side circuits and the problems in the manufacturing process.

Further, on the first insulated metal substrate or the second insulated metal substrate, at least a variable resistor for setting the overcurrent detection level of the primary side circuit, a variable resistor for setting the voltage of the secondary side circuit, or a variable resistor for setting the overvoltage detection level is provided. A variable resistor 1 is mounted, and the resistance can be adjusted at the user side or at least in the final stage of manufacturing through a gap between the first and second insulated metal substrates or through a hole formed in the casing. By doing so, it meets the needs of many users.

(E) Function By coupling the first and second insulated metal substrates, on which the primary and secondary circuits of the switching power supply circuit are specially mounted, using a photocoupler, it is possible to treat them as the metal substrates of the body. , the element mounting process, the REIT fixing process, etc. can be simplified to the same level as those for a single board. Furthermore, since the two metal substrates are coupled using a photocoupler, the distance between the first and second insulating metal substrates can be set with high precision.

Furthermore, since it is possible to adjust the resistance of at least one of the variable resistor for setting the overcurrent detection level, the variable resistor for setting the voltage, or the variable resistor for setting the overvoltage detection level, it is possible to immediately respond to changes in standards.

(F) Embodiments First, the outline and structure of the switching power supply device of the present invention will be explained with reference to FIGS. 4 and 5. Note that any converter-type switching power supply circuit, including the switching power supply circuit described in 1 in the description of the conventional example, can be used in the switching power supply device of the present invention, and therefore a description of the circuit configuration will be omitted.

Referring to FIG. 4, the switching power supply device of the present invention includes two hybrid integrated circuit boards (1) each mounted with a primary side circuit and a secondary side circuit separated by an isolation transformer (not shown because it is externally connected). 20) (20), leads (56) (58) led out from the peripheral edges of each of the two hybrid integrated circuit boards (20) (20>), two hybrid integrated circuit boards (20) (20); A photocoupler (
50) and a casing (10) which is generally frame-shaped and includes a step (12) serving as a guide for a spacer called a surfboard.

Two hybrid integrated circuit boards (20) (20) are arranged on the same plane with a predetermined distance apart, and their peripheral edges are connected to the casing (1).
It is fixed to the step part of 0) using an adhesive sheet or the like. The primary and secondary side circuits of the switching power supply circuit mounted on the hybrid integrated circuit board (20) (20) are independent seals formed by the hybrid integrated circuit board (20) (20) and the casing (10). The circuits are arranged in a space, and the circuits are coupled to the transformer through leads (56) and (58). Further, feedback of voltage and overvoltage signals from the secondary circuit to the primary circuit is performed by a photocoupler (50). In addition, n8 where this photocoupler (50) is placed
The area is sealed with a cover (not shown).

In the switching power supply shown in Fig. 4,
The resistance of the variable resistance element (52) is adjusted by the first and second
Since this is done through the substrate gap between the hybrid integrated circuit boards (20) (20), it is impossible to adjust the resistance after it is attached to a heat sink, for example. On the other hand, in the embodiment shown in FIG. 5, a hole (14) for adjusting the resistance of the variable resistance element (52) is formed in the casing (10), so that the resistance can be adjusted at any time.

Next, the manufacturing process of an example will be explained in order to clarify the features of the present invention.

FIG. 1A shows a plan view of a circuit board immediately before circuit components are mounted to form a hybrid integrated circuit board, and FIG. 1B is a sectional view taken along the line I-1.

The metal substrate (20) is made of aluminum or the like with a thickness of 0°5 mm.
A ~3 mm metal substrate is used and press punched into a rectangular shape with a rectangular cut hole (24) in its center, as illustrated in FIG. 1A.

When aluminum is used, an oxide film is formed by anodizing after this, and a copper foil with a thickness of 18 μm to 35 μm is laminated with an insulating resin layer (26) of polyimide or enamelled wood with a thickness of about 35 μm. The body is attached. This copper foil is then etched into a predetermined shape to form a circuit pattern (2
8), pads (30) and (32) for external leads, pads (34) for photocouplers (50), and hoods (36) for variable resistance elements, etc. are formed.

Referring to FIG. 2, the circuit board completed as described above includes a switching element (40), a PWM circuit (42), an overcurrent detection circuit (42), and an overcurrent detection circuit (42) constituting a switching power supply circuit.
4), Dio-1' (46), Overvoltage detection circuit (48)
), or elements such as resistors and capacitors are mounted in chip form. A photocoupler (50) is fixed to the pad (30) (34) so as to straddle the rectangular hole (24), and a lead (56) is fixed to the pad (30) (32).
) (58) are fixed by solder. As the variable resistance element (52), any type of variable resistance element for surface mounting, such as a dimple type or a trimmer type, is used, and if necessary, the casing (1
0), or fixed in an adjustable arrangement through a recessed hole (24).

By adopting a structure in which the resistance of this variable resistance element (52) can be adjusted on the user side, or at least in the final stage of manufacturing the hybrid integrated circuit device, the switching power supply device of the present invention can be achieved. It can immediately respond to the needs of an extremely large number of users. Thereafter, predetermined electrodes and circuit patterns are connected by wire bonding.

These mounting steps and the circuit pattern etching steps described above are performed in the same manner as in the manufacture of a hybrid integrated circuit device using a single substrate.

Next, the bridge (22) and lead frame (54) connecting the circuit boards on the left and right sides of the holes in the hybrid integrated circuit board (20 (20')) on which the element mounting and the fixing of the leads (46) have been completed are press punched. The two hybrid integrated circuit boards (20) are removed by the photo coupler (50), and the two hybrid integrated circuit boards (20) are connected only by the photo coupler (50) (see Figure 3). Since it is fixed by fixing (50), the substrate spacing specified by safety standards is guaranteed even in the subsequent manufacturing process.

(G) Effects of the Invention As described above, according to the present invention, (1) Since an insulated metal substrate is used, heat dissipation characteristics are good, and it can be applied to a large-capacity switching power supply device.

(2) Even though safety standards are met because the primary and secondary circuits of the switching power supply circuit are completely separated, etching and mounting processes are simplified to the same level as processing a single board. be able to.

(3) It is possible to adjust at least 61 resistances of the variable resistor for setting the overcurrent detection level, the variable resistor for setting the voltage, or the variable resistor for setting the overvoltage detection level, so that it can immediately meet the needs of a large number of users.

(4) Since the circuit is formed on a single substrate with holes formed therein, the lead pads and the photocoupler pads formed on each substrate are aligned.

[Brief explanation of the drawing]

1 to 4 are diagrams explaining the manufacturing process of an embodiment of the present invention, in which FIG. 1A is a plan view of a circuit board used in the embodiment, and FIG. 1B is a plan view of the circuit board used in the embodiment. ■ Line sectional view, Figure 2 A
is a plan view of a hybrid integrated circuit board on which circuit elements are mounted;
Figure B is a sectional view taken along line I-1, Figure 3 is a plan view of the completed hybrid integrated circuit board, Figure 4 is a perspective view of the embodiment, Figure 5 is a perspective view of a modified example, and Figure 6 is a general view. A circuit diagram of a switching power supply circuit. (10) - Casing, (12) - Circon guide, (20) - Hybrid integrated circuit board, (22) -
Bridge, (24L-・Sunk hole, (28)...Circuit pattern, (30) (32n (34) (36)...Pad. Hatakeganjin Sanyo Electric Co., Ltd.

Claims (1)

[Scope of Claims] (1) A first insulated metal substrate mounting a plurality of circuit elements such as a switching element constituting a primary side circuit of a switching power supply circuit and a circuit that controls the operation of this switching element; The second circuit is equipped with multiple circuit elements such as diodes and overvoltage detection circuits that constitute the secondary side circuit of the power supply circuit.
The insulated metal substrate and the first and second insulated metal substrates are coupled at a predetermined interval on the same plane, and voltage signals and overvoltage signals are insulated and fed back from the secondary side circuit to the primary side circuit of the switching power supply circuit. A casing comprising a photocoupler and a space for independently sealing a primary side circuit and a secondary side circuit of a switching power supply circuit mounted on the first and second insulated metal substrates, and a first insulated metal substrate. At least one of a variable resistor for setting an overcurrent detection level of a primary side circuit, a variable resistor for setting a voltage of a secondary side circuit, or a variable resistor for setting an overvoltage detection level is mounted on the substrate or the second insulated metal substrate, A switching power supply device characterized in that a hole is formed in the casing so that a position corresponding to the variable resistor is exposed. (2) The switching power supply device according to claim 1, wherein the first and second insulated metal substrates are formed by cutting a bridge of a single insulated metal substrate in which a rectangular cut hole is formed. (3) The switching power supply device according to claim 2, wherein the width of the cut hole is set to a size that satisfies a required insulation standard. (4) The leads led out from the first and second insulating metal substrates are fixed to one peripheral edge of the single insulating metal substrate before the single insulating metal substrate is separated by cutting the bridge. Switching power supply as described.