JPH0327763A - Power source circuit - Google Patents

Abstract

PURPOSE:To provide a low-cost high-output power source by using diodes to switch capacitors. CONSTITUTION:DC voltage V of a power source 10 is supplied to a step-down unit 14 through the contact of a changeover switch 12. This unit 14 switches a line 16 alternately to a power source hot line 18 and an earth line 20 at regular time interval. The unit 14 is equipped with three capacitors C1-C3, an output capacitor C4, and diodes D1-D8 for changing the connection of the capacitors between charge mode and discharge mode.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a power supply circuit for converting a high voltage, small current to a low voltage, large current, and achieves this in a compact and low cost manner.

[Conventional technology]

When power is supplied to electrical equipment such as audio equipment that does not have a built-in power transformer, commercial power is converted into the required DC power using an AC adapter or the like, and then transmitted via a cable.

Place for audio equipment, etc. In general, many of them operate at a voltage of 3 to 12 V, which is a low voltage operation, but a correspondingly large amount of current is required. For this reason, if power is supplied using a thin cable, the loss due to the resistance of the cable increases, so a somewhat thick cable is required.

To solve this problem, it is conceivable to supply DC power with high voltage and small current to the cable, convert it to low voltage and large current inside the electrical equipment, and use it.

Conventionally, switching regulators and CMOS step-down circuits have been used as devices to convert high voltage, small current DC power supplies to low voltage, large current.

A CMOS step-down circuit connects multiple capacitors to many CMOS
Use the S switch to alternately switch between series connection and parallel connection, and when connected in series, connect to the power supply to charge each capacitor (each capacitor is charged with a voltage obtained by dividing the power supply voltage equally), When connected in parallel, the capacitors are connected to a load so that the equally divided voltages are supplied from each capacitor.

[Problem to be solved by the invention] When converting using a switching regulator,
Since a transformer is required inside the electrical equipment, there is a problem of increased costs. Furthermore, in order to reduce the weight, it is necessary to use high frequencies, which poses a problem of noise generation.

In addition, CMOS step-down circuits require many CMOS switches, which are active elements, and discrete elements (MOS
If a transistor, MOSFET) is used, the cost will be high. For this reason, the CMOS step-down circuit is
Normally, the large number of CMOS switches is not a problem.I
Since it is based on the premise of C conversion, it is limited to applications that require extremely low power, and is not suitable for driving mechanisms of electrical equipment or as power sources for power amplification.

The present invention solves the problems in the conventional technology, eliminates the need for a transformer such as a switching regulator, eliminates the problem of noise generation, and uses CMOS
The present invention aims to provide a power supply circuit that can convert a high voltage and small current into a low voltage and large current without requiring a large number of CMOS switches such as a step-down circuit.

[Means to solve the problem]

The present invention provides a DC power source, a step-down unit, and a charging mode in which the step-down unit is charged by connecting the DC power source and the step-down unit; and a changeover switch for alternately switching to a discharging mode in which the step-down unit is disconnected and discharged, and the step-down unit connects a plurality of capacitors, an output capacitor, and a forward direction in the charging mode, a charging path configuring diode which connects the capacitors in series and charges them with the DC power supply, and which operates in a reverse direction to mutually disconnect the plurality of capacitors during the discharge mode; a discharge path configuration in which the plurality of capacitors are individually connected to the output capacitor to charge the output capacitor, and the direction is reversed during the charging mode to mutually disconnect the individual capacitors and the output capacitor; It is equipped with a diode for

[For production]

According to this invention, when the step-down unit is in charge mode, the capacitors are connected in series, and each capacitor is charged with a voltage obtained by dividing the power supply voltage, and when in discharge mode, each capacitor is connected in parallel to the output capacitor, and the output capacitor is is charged to the above-mentioned divided voltage, thereby converting a high voltage and small current to a low voltage and large current.

In this case, the switching of the capacitor connection is realized by a diode, which is a passive element, without using a CMOS switch, so it can be constructed at low cost using discrete elements, and relatively large power can be obtained, and it can be used as a power source for electrical equipment. You can obtain something suitable for this purpose. Also, there is no problem of noise generation like with switching regulators.

〔Example〕

An embodiment of this invention is shown in FIG. This is the power supply voltage V
It is designed to obtain an output voltage that is 1/3 of the output voltage.

The power supply 10 outputs a DC voltage of voltage V.

This DC voltage V is supplied to the step-down unit 14 via the contact a of the changeover switch 12. The step-down unit 14 alternately switches the line 16 to the power supply hot line 18 (contact a) or the ground line 20 (contact b) at regular intervals. For example, as shown in FIG. 2, the changeover switch 12 can be constructed of two transistors Ql and Q2 that are turned on and off alternately.

The step-down unit 14 houses three capacitors C1 to C3 and an output capacitor C4.
2 is connected to the contact a side (charging mode), the capacitors C1 to C3 are connected in series and charged by the power supply voltage V (each capacitor C1 to C3 is charged to 3/V), and the changeover switch 12 At the timing when is connected to the contact b side (discharge mode), the capacitors C1 to C3 are disconnected from each other and connected in parallel to the output capacitor C4, and the capacitor C4 is charged to 3/V. The output is obtained from both ends 22a, 22b of capacitor C4.

Switching between capacitor connection in charging mode and capacitor connection in discharging mode is performed by a diode. That is, when the changeover switch 12 is connected to the contact a side, the forward direction is connected between the capacitors CI and C2, between C2 and C3, between C3 and the ground line 20, and the capacitors C1 to C3 are connected to each other.
C3 are connected in series and charged by the power supply 10,
When the changeover switch 12 is connected to the contact b side, charging path control diodes D1 to D3 are connected, respectively, so that the voltage of the capacitors 01 to C3 reverses the direction and disconnects the capacitors C1 to 03 from each other. There is.

A capacitor C1 is connected between one end of the capacitor C1 and one end of the output capacitor C4 in the discharge mode.
4 and is connected to a discharge path forming diode D6 which disconnects this connection in the charging mode. Capacitor C2
between one end of the switch 12 and the capacitor C2
Discharge path structure diodes D4 and D7 are connected between the other end and one end of the output capacitor C4, respectively, to connect the capacitor C2 to the output capacitor C4 in the discharge mode and disconnect this connection in the charge mode. There is.

A capacitor C3 is connected between one end of the capacitor C3 and the selector switch 12 and between the other end of the capacitor C3 and one end of the output capacitor C4 in the discharge mode.
4 and are connected to discharge path forming diodes D5 and D8 which disconnect this connection in the charging mode.

Note that diodes D4 and D5 are connected to the power supply 10 in charging mode.
It also has the function of preventing the capacitors C2 and C3 from being directly connected. The diodes D6 to D8 also have the function of preventing connection between [[10 and the output capacitor C4] during the charging mode.

According to the circuit shown in FIG. 1, the changeover switches 12 are alternately switched at a constant cycle. In this case, at the timing when the changeover switch 12 is connected to the contact a side, the step-down unit 14 enters the charging mode, and the power supply 10 → changeover switch 1
A power supply voltage V is supplied from the power supply 10 via the route 2-CI-DI-C2→D2→C3→D3→power supply 10, and the capacitors C1 to C3 are each charged to V/3.

At the timing when the changeover switch 12 is connected to the b side, the step-down unit 14 enters the discharge mode, and the route is C1 → changeover switch 12 → C4 → D6 → C1, and the route of C2 → D4 all changeover switch 12 → C4-D7 → C2. And C3 →
Routes D5→changeover switch 12→C4→D8→C3 are formed, and capacitors C1 to C3 are connected in parallel to output capacitor C4. As a result, the output capacitor C4 is charged to V/3, and this voltage is transferred to the output terminals 22a. Obtained between 22b and 22b.

In addition, the current capacity that can be supplied from the output capacitor C4 is
This is three times the current capacity due to the series connection of capacitors 01 to C3. In this way, conversion from high voltage and small current to low voltage and large current is realized.

FIG. 3 shows the waveforms of the respective parts indicated by A-G in the circuit of FIG. 1 at startup. According to this, it can be seen that a voltage of -V/3 is obtained at the output (G).

Note that in the circuit shown in FIG. 1, the charging mode and the discharging mode are alternately switched, so the power supply 10 is used only in half-wave mode, but as shown in FIG. Connect two pieces in parallel and set the changeover switch 12.
By switching 12' in opposite directions, the power supply 10
can be used for both waves, and the current capacity can be doubled compared to the case shown in FIG.

(Application Example) An example of a system for transmitting power using the power supply circuit of the present invention is shown in FIG. This unit integrates a control function section 26 that performs remote control transmission as an operation section 24, and a source playback function section 28 (in this case, a cassette deck 30 and a CD player) that requires source exchange. By separating the playback device 36 and speakers 36, 38, etc., remote control transmission and exchange of tapes and CDs can be performed from a location away from the playback device main body 34.

The operating section 24 and the playback device main body 34 are connected by a cable 38. The cable 38 transmits operation commands of the control function unit 26 to the playback device main body 34, and conversely transmits and displays the operating status of the playback device main body 34 to the operation unit 24, thereby realizing interactive digital transmission. Control cable, cassette deck 30 and CD player 32
A reproduction signal cable for transmitting a reproduction signal to the reproduction apparatus main body 34, a power cable for supplying operational power from the reproduction apparatus main body 34 to the cassette deck 30, CD player 32, and control function section 26, and the like are accommodated.

The present invention is utilized for this power supply, and the power supply circuit according to the present invention is housed in the operating section 24, and high voltage and small current are transmitted from the playback device main body 34 to the cable 38, and the low voltage and large current are transmitted within the operating section 24. By converting it into an electric current, power can be supplied using a small diameter cable 38. Furthermore, since no transformer is used, the operating section 24 can be made smaller and lighter. Moreover, there is no noise problem like with switching regulators.

[Example of change]

In the above embodiment, the case where a voltage of 1/3 of the power supply voltage is obtained has been described, but it is also possible to obtain a voltage with other voltage division ratios. Even in that case, the number of changeover switches does not need to be increased, and the configuration can be made at low cost, just by increasing the number of diodes that are passive elements.

〔Effect of the invention〕

As explained above, according to the present invention, the voltage drop is achieved by switching the connection of the capacitor using a diode, which is a passive element, without using a CMOS switch, so it can be constructed at low cost using discrete elements. A relatively large amount of electric power can be obtained, making it suitable for uses such as power sources for electrical equipment. Also, there is no problem of noise generation like with switching regulators.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention. FIG. 2 is a circuit diagram showing an example in which the selector switch 12 of FIG. 1 is replaced with an analog switch. FIG. 3 is an operational waveform diagram of each section indicated by A to G in FIG. 1 at the time of startup. FIG. 4 is a circuit diagram showing an example of a dual-wave configuration using two step-down units. FIG. 5 is a diagram showing the system configuration of an audio device that supplies power using the radio wave circuit of the present invention. 10... DC power supply, 12... Selector switch, 14.
... Step-down unit, C1 to C3... Plural capacitors, 4... Output capacitor, D1 to D3... Diodes for forming charging path, D4 to D8... Diodes for forming discharge path.

Claims (1)

[Claims] A DC power source, a step-down unit, and a charging mode in which the step-down unit is charged by connecting the DC power source and the step-down unit; and a changeover switch that alternately switches to a discharging mode in which the step-down unit is disconnected from the unit and discharges the step-down unit, and the step-down unit has a plurality of capacitors, an output capacitor, and a forward direction in the charge mode, a charging path configuring diode that connects the plurality of capacitors in series and charges them with the DC power source, and reverses direction in the discharge mode to mutually disconnect the plurality of capacitors; and the plurality of capacitors are individually connected to the output capacitor to charge the output capacitor, and in the charging mode, the discharge direction is reversed to disconnect the individual capacitors and the output capacitor from each other. A power supply circuit comprising a circuit configuring diode.