JP3181441B2 - Thin power supply - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin power supply having a rectifier circuit driven by a high-frequency inverter.

[0002]

2. Description of the Related Art Mobile OA equipment and communication terminals have small and thin main bodies, so that power supplies are naturally required to be small and thin. Conventionally, a thin power supply of this type
A circuit driven by a 0 kHz high-frequency inverter and composed of a rectifying diode, a smoothing inductor and a capacitor is often used. And about the implementation of this circuit,
It is configured by mounting a thin surface-mounted component on a metal substrate. With this structure, 10mm output and 3mm thickness
About 5 mm.

[0003]

In this type of thin power supply, when the operating frequency of the inverter is increased,
The dimensions of the transformer and the smoothing capacitor decrease in inverse proportion to the frequency. (If the inverter is non-insulated, magnetic components such as choke coils are used instead of transformers.) However, the capacitance of the smoothing capacitor is generally reduced to reduce ripple. And the size becomes larger. That is, the required capacity is required in proportion to the load current / voltage ratio. Therefore, in order to satisfy the size limitation of the thin power supply device, the size of the smoothing capacitor, particularly the height limitation, is important. SUMMARY OF THE INVENTION It is an object of the present invention to provide a thin power supply device that can make the thickness of the thin power supply device smaller than before while maintaining predetermined characteristics of the thin power supply device.

[0004]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention comprises a thin magnetic component mounted on a surface of a substrate, a rectifier, a pair of output terminals, and a smoothing capacitor. In the thin power supply device, the smoothing capacitor has a height equal to or less than the height of the magnetic component, and is formed by connecting a plurality of thin capacitors in parallel,
A thin resistor is connected in series to each of these thin capacitors, and each of the thin capacitors and the thin resistors connected in series is disposed across a pair of long lands formed separately on the substrate. And a connected thin power supply device.

[0005]

[0006]

FIG. 1 is a circuit block diagram for explaining one embodiment of a thin power supply device according to the present invention, and FIG. 2 is a mounting diagram of the thin power supply device according to one embodiment of the present invention. First, regarding the circuit configuration, as shown in FIG.
The DC is received from 3, and converted to about 500 kHz by the inverter 5 and sent to the primary winding of the transformer 7. The high frequency voltage of the secondary winding of the transformer 7 is rectified by the diodes 9 and 11. Further, by a parallel circuit of the smoothing inductor 13 and the smoothing capacitors 15, 17, 19, 21, 23, a flatter DC is output between the output terminals 35, 37.

The transformer 7 is constituted by combining a sheet-shaped coil patterned on a flexible substrate with a thin ferrite core. Further, the inductor 13 is similarly configured. The primary and secondary are insulated by the transformer 7, but if the insulation is not required, the transformer 7 can be omitted and replaced with an inductor as a chopper circuit.

FIG. 2 shows the mounting of this thin power supply device.
As shown in (1), all components are surface-mounted on a metal substrate 2 having a predetermined conductive pattern formed on an insulating coating of a metal plate. However, the input terminals 1 and 3 and the inverter 5 are not shown. One of the secondary winding terminals of the transformer 7 is connected to the elongated land 51 and extends to the output terminal 37 at the end of the metal substrate 2. The other of the secondary winding terminals of the transformer 7 is connected to the long land 53 via the diodes 9 and 11 for rectification and the inductor 13, and is extended to the output terminal 35 at the end of the metal substrate 2. You. The long lands 51 and 53 are located in parallel to each other, and smoothing capacitors 15, 17, 19, 21, and 23 are connected in parallel between them. The height of these smoothing capacitors 15, 17, 19, 21, and 23 should be about the same as or less than the height of the transformer 7, and the number of these capacitors in parallel should satisfy the capacitance required as a smoothing capacitor. Is determined.

FIG. 3 is a circuit block diagram of a second embodiment of the thin power supply according to the present invention. In FIG.
Elements having the same reference numerals correspond to the same elements. In this embodiment, resistors 25, 27, 29, 31, 33 are respectively connected in series to capacitors 15, 17, 19, 21, 23 for smoothing. As shown in FIG. 4, the resistors 25, 27, 29, 31, 33 are mounted between the capacitors 15, 17, 19, 21, 23 and the long land 53 as shown in FIG. , 33 are arranged.

The resistors 25, 27, 29, 31, 33 have a resistance value of 1Ω or less, and the smoothing capacitors 15, 17, 19, 21, 23.
By connecting them in series with each other, a slight loss is included in the capacitor, and the function of suppressing the turbulence of the feedback system of the power supply device is achieved. The lower limit for a thin-type resistor for surface mounting is about 1Ω, but the smoothing capacitor is configured in parallel, divided and connected to each resistor to reduce the equivalent series resistance value for the above purpose. Can be set to an appropriate value as a constant for In addition, since the resistors are divided and mounted, the generated heat can be dispersed and the temperature rise can be suppressed.

[0011]

As described above, according to the present invention, a plurality of thin capacitors having a height equal to or less than the height of a magnetic component are arranged in parallel across a pair of long lands on a substrate. As a result, the thickness of the power supply unit can be made smaller than before while maintaining the predetermined characteristics, and the smoothing capacitor is divided into a plurality of parts.
The surface area is increased and therefore the heat dissipation is better.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram of one embodiment of a thin power supply device according to the present invention.

FIG. 2 is a mounting diagram of one embodiment of the thin power supply device according to the present invention.

FIG. 3 is a circuit block diagram of a second embodiment of the thin power supply device according to the present invention.

FIG. 4 is a mounting diagram of a second embodiment of the thin power supply device according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Input terminal 2 ... Metal board 3 ... Input terminal 5 ... Inverter 7 ... Transformer 9 ... Diode 11 ... Diode 13 ... Inductor 15,17,19,21,23 ... Capacitor 25,27,29,31,33 ... Resistance 35, 37… Output terminal 51 53… Long land

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H02M 1/14 H02M ^7/ 00-7/40

Claims (1)

(57) [Claims] 1. A thin power supply device comprising a thin magnetic component mounted on a surface of a substrate, a rectifier, a pair of output terminals, and a smoothing capacitor, wherein the smoothing capacitor has a height higher than that of the magnetic component. Equivalent to
Or a plurality of thin capacitors having a height of less than that connected in parallel, thin resistors are connected in series to each of these thin capacitors, and each of the thin capacitors and the thin resistors connected in series is provided on the substrate. A thin power supply device which is arranged and connected across a pair of elongated lands formed apart from each other.