JPH09191639A - Dc/dc converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the size and weight while saving energy by providing a semiconductor switch and a capacitor and connecting at least two capacitors in series. SOLUTION: The input terminals 50, 51 and the output terminals 52, 53 of an integrated circuit 1 are connected conventionally but external capacitors 6, 7 are connected in series. Consequently, the number of connection terminals can be decreased by one as compared with conventional case. Since the number of connection terminals is decreased by connecting the external capacitors 6, 7 in series and the number of semiconductor switches can be decreased by shifting the operating time of semiconductor switches, the size and weight can be reduced. Furthermore, energy can be saved because the number of semiconductor switches is decreased and thereby the current loss of semiconductor switch can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC / DC converter for converting a DC voltage supplied to a mobile phone, a personal computer, a video camera or the like into a required DC voltage.

[0002]

2. Description of the Related Art Conventional DC / DC converters are generally composed of a chopper converter, a flyback converter, a fored converter, etc., but in recent years, a charge pump system (switch) combining a semiconductor switch and a capacitor has been used. DC /)
Since the DC converter is suitable for miniaturization, it is used particularly for low power applications.

A circuit configuration of a conventional DC / DC converter will be described with reference to FIG. In FIG. 3, the input power supply 2 and the smoothing capacitor 3 are connected to the input terminals 50 and 51 of the integrated circuit 1 incorporating the semiconductor switch, and the output terminals 52 and 5 are connected.
A load 5 and a smoothing capacitor 4 are connected to 3, and
Capacitors 6 and 7 are connected to the capacitor terminals 54, 55, 56 and 57, respectively. The operation mode of the semiconductor switch of the integrated circuit 1 is as shown in FIG. 6, and when the semiconductor switches 11, 12, 13, and 14 are ON,
The semiconductor switches 21, 22, 24 are off. When the semiconductor switches 21, 22, 24 are ON, the semiconductor switches 11, 12, 13, 14 are OFF. When the semiconductor switches 11, 12, 13, and 14 are turned on, the input voltage is applied to the capacitor 6 through the semiconductor switches 11 and 12, so that the capacitor 6 is charged by this input voltage and, at the same time, is input through the semiconductor switches 13 and 14. The capacitor 7 is also charged to the input voltage. Next, when the semiconductor switches 21, 22, and 24 are turned on, the capacitors 3, 6, and 7 are connected by the semiconductor switches 21, 22, and 24.
And 5 are connected in series and applied to the capacitor 4 and the load 5 through the series portion,
Is supplied with three times the input voltage.

Further, in FIG. 4 showing another structure of the conventional system, when the semiconductor switches 11 to 16 are ON, the semiconductor switches 11 and 12, 13 and 14, and 15 and 16 are shown.
Therefore, the input voltages are applied and charged to the capacitors 6, 7 and 8, respectively. In FIG. 4, the same reference numerals as those in FIG. 3 represent the same components as those in FIG. FIG.
Then, when the semiconductor switches 21 to 24 are turned on, the semiconductor switches 21 to 24 are applied to the capacitor 4 and the load 5 through the series circuit composed of the capacitors 3, 6, 7 and 8 to supply a quadruple voltage.

[0005]

In recent years, in the field of DC / DC converters, there has been a strong demand for energy saving (high efficiency, long life) as well as a demand for smaller size and lighter weight. Therefore, semiconductor switches and connections are required. It is necessary to reduce the number of terminals as much as possible. However, the above-mentioned conventional device has a problem in that it is difficult to reduce the number of semiconductor switches and connection terminals in terms of circuit configuration, and thus it is difficult to achieve reduction in size and weight and energy saving. In addition, in the configuration of the conventional method that combines a semiconductor switch and a capacitor, since there is no transformer and the input and output insulation types cannot be performed, the positive output and the negative output have to use different designs. There is a problem that it is difficult to achieve miniaturization and weight reduction.

Therefore, according to the present invention, in order to realize size reduction, weight reduction and energy saving (high efficiency, long life), the number of semiconductor switches and connection terminals can be minimized in DC / DC. The purpose is to provide a converter.

[0007]

In order to solve the above problems, the present invention employs a DC / DC converter having a semiconductor switch and a capacitor, and at least two capacitors connected in series. . According to the present invention, a charge pump type DC-D in which at least two semiconductor switches are connected to a series connection point of capacitors
A C converter can be constructed. Further, in the present invention, a semiconductor switch between the input terminal and the capacitor,
Charge pump type D that is insulated by not turning on the semiconductor switch between the output terminal and the capacitor at the same time
A C-DC converter can be constructed.

According to the present invention, the number of connection terminals of the external capacitor can be reduced and the number of connection terminals of the external capacitor can be reduced by connecting the external capacitor (which is a capacitor externally attached to the integrated circuit) in series. The number of semiconductor switches can be reduced by shifting the operation in time. As described above, according to the present invention, since the number of connection terminals of the external capacitor and the number of semiconductor switches can be reduced, it is possible to reduce the size and weight of the DC / DC converter. Furthermore, since the current loss due to the semiconductor switches can be reduced by reducing the number of semiconductor switches, it is possible to save energy.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION An example of the circuit configuration of a DC / DC converter of the present invention will be described with reference to FIG. In FIG. 1, the same reference numerals as those in FIG. 3 represent the same components as those in FIG. In FIG. 1, the input terminals 50 and 51 of the integrated circuit 1 are shown.
The output terminals 52 and 53 are connected in the same manner as in the conventional system shown in FIG. 3, but the number of connection terminals is one less than that in FIG. 3 because the external capacitors 6 and 7 are connected in series. is made of. The circuit operation of FIG. 1 will be described with reference to FIG. When the semiconductor switches 11 and 12 are ON, the semiconductor switches 21, 22, 31, 32 are OFF. At this time,
The input voltage is applied and charged to the capacitor 6 through the semiconductor switches 11 and 12. Next, the semiconductor switches 21 and 2
When 2 is ON, semiconductor switches 11, 12, 3
Since 1 and 32 are off, the input voltage is applied and charged to the capacitor 7 through the semiconductor switches 21 and 22. Next, when the semiconductor switches 31 and 32 are turned on, the semiconductor switches 11, 12, 21, 22 are turned off, so that the capacitors 4 and 5 are applied and charged through the series circuit of the capacitors 3, 6 and 7. The input voltage is 3
Double voltage is supplied to the load 5.

Next, an example of the quadruple voltage circuit in the DC / DC converter of the present invention will be described with reference to FIG. Note that FIG.
4, the same reference numerals as those in FIG. 4 represent the same components as those in FIG. In FIG. 2, the connection between the input terminals 50, 51 and the output terminals 52, 53 is the same as that in FIG. 4, but the connection terminals 54, 55, 57, 59 of the capacitors 6, 7, 8 are compared to the conventional FIG. Therefore, the total number of the connection terminals is reduced by two. Further, the total number of semiconductor switches of the integrated circuit 1 is two less than that of FIG. Next, the operation of FIG. 2 will be described with reference to FIG. Semiconductor switches 11 and 1
When 2 is ON, other semiconductor switches are OF
F. At this time, the input voltage is applied and charged to the capacitor 6 through the semiconductor switches 11 and 12. When the semiconductor switches 21 and 22 are turned on, the other semiconductor switches are turned off.
The input voltage is applied and charged to the capacitor 7 through 2.
Similarly, when only the semiconductor switches 31 and 32 are turned on,
The input voltage is applied and charged to the capacitor 8. When the semiconductor switches 41 and 42 are turned on, the other semiconductor switches are turned off. Therefore, in the series circuit of the capacitors 3, 6, 7 and 8, the capacitor 4 and the load 5 have a voltage four times the input voltage. Is supplied.

As a method for controlling and adjusting the output voltage (load voltage), as in the conventional method, a time during which all the semiconductor switches are turned off is made and any (or all) semiconductor switches are turned on. By shortening the time,
The voltage charged in the capacitor can be lowered.
Further, the output voltage can be stabilized by detecting the output voltage, comparing it with the reference voltage, amplifying the error voltage, and controlling the ON time of the semiconductor switch.

Next, since there is no transformer in the conventional system in which a semiconductor switch and a capacitor are combined, naturally the input and the output cannot be insulated by the transformer. Therefore, in the conventional device, it is necessary to use different designs for the positive output and the negative output, which makes it difficult to reduce the size and weight. As a means for solving this problem, FIG. 5 shows an example of a circuit configuration in which the input and output insulation types can be configured by a method of combining a semiconductor switch and a capacitor in the present invention.
In FIG. 5, the same reference numerals as those in FIG.
It represents the same component part as. In FIG. 5, the connection between the input terminal, the output terminal and the capacitor terminal of the integrated circuit 1 is
It is similar to FIG. However, in FIG. 5, the connections of the semiconductor switches inside the integrated circuit 1 are different from those in FIG. The operation of FIG. 5 is the same as that of FIG. When the semiconductor switches 11 and 12 are turned on, the other semiconductor switches are turned off, so that the input voltage is applied and charged to the capacitor 6. Similarly, when only the semiconductor switches 21 and 22 are turned on, the capacitor 7 is turned on and the semiconductor switches 31 and 32 are turned on.
With only ON, the capacitor 8 is applied and charged. When only the semiconductor switches 41 and 42 are turned on, the series circuit of the capacitors 6, 7 and 8 is connected to the capacitor 4 and the load 5, and a voltage three times the input voltage is supplied. When the semiconductor switches 41 and 42 are ON, the other semiconductor switches are OFF, and when the other semiconductor switches are ON, the semiconductor switches 41 and 42 are OF.
Since it is F, the input terminal and the output terminal of the integrated circuit 1 are insulated by turning off any one of the above semiconductor switches. Therefore, the input terminal 50 and the output terminal 5 of the integrated circuit 1 are
When 3 is connected, a negative output voltage that is three times the input voltage is generated. Further, when the input terminal 50 and the output terminal 52 of the integrated circuit 1 are connected, a positive output voltage that is three times the input voltage is generated. Furthermore, if the connection between the capacitor 4 and the load 5 that was connected to the output terminal 52 is changed to the input terminal 50 and the output terminal 52 is connected to the input terminal 51, the same connection as in FIG. A positive voltage can be supplied to the load 5.

[0013]

【The invention's effect】

(1) According to the present invention, an external capacitor is connected in series to reduce the number of connection terminals of the external capacitor, and
By shifting the operation of the semiconductor switches in time, the number of semiconductor switches can be reduced, so that the size and weight can be reduced. Further, since the current loss of the semiconductor switches can be reduced by the number of the semiconductor switches, it is possible to save energy. Therefore, a compact and highly efficient DC / DC converter can be designed and manufactured. (2) An input / output insulation type DC / DC converter can be configured by a circuit configuration in which a semiconductor switch and a capacitor are combined.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a circuit configuration of a DC / DC converter of the present invention.

FIG. 2 is a diagram showing an example of a circuit configuration of a DC / DC converter of the present invention.

FIG. 3 is a diagram showing a circuit configuration example of a conventional DC / DC converter.

FIG. 4 is a diagram showing a circuit configuration example of a conventional DC / DC converter.

FIG. 5 is a diagram showing an example of an insulation type circuit configuration in the DC / DC converter of the present invention.

FIG. 6 is a diagram illustrating the operation of FIGS. 3 and 4;

FIG. 7 is a diagram for explaining the operation of FIG.

FIG. 8 is a diagram for explaining the operation of FIGS. 2 and 5.

[Explanation of symbols]

1 integrated circuit, 2 input power supply, 3 capacitors, 4 capacitors, 6 capacitors, 7 capacitors, 8 capacitors, 5 loads, 11 terminals, 12 terminals, 13 terminals, 14 terminals, 15 terminals, 16 terminals, 21 terminals,
22 terminals, 23 terminals, 24 terminals, 31 semiconductor switches, 32 semiconductor switches, 41 semiconductor switches,
42 semiconductor switch, 50 terminal, 51 terminal, 52
Terminal, 53 terminal, 54 terminal, 55 terminal, 56
Terminal, 57 terminal, 58 terminal, 59 terminal.

Claims (3)

[Claims] 1. A DC / DC converter comprising a semiconductor switch and a capacitor, wherein at least two capacitors are connected in series. 2. At least two capacitors are connected at a series connection point.
2. A charge pump type DC-DC converter to which a plurality of semiconductor switches are connected.
The DC / DC converter described in 1. 3. A charge pump type DC-DC converter which is insulated by not simultaneously turning on a semiconductor switch between an input terminal and a capacitor and a semiconductor switch between an output terminal and a capacitor. The DC / DC converter according to claim 1 or 2.