JPH1094193A - Power supply circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow an extended long time continuous operation of a power circuit by the power of a battery and obtain a high audio output by using an AC adaptor by making the power circuit in such a structure, that one of the power supplies may be connected to a series regulator and the other to a DC/DC converter though a relay and the relay may be switched over, according to the supply voltage. SOLUTION: The output which has been converted to DC by an AC adaptor 2 or the output of a dry battery 11 connected with a reverse current blocking diode 4 is used as the supply voltage. The supply voltage from one of the power supplies is input to a 5V regulator 12 and the one from the other power supply to a 5V DC/DC converter 13 through a relay 8 to be converted to a constant voltage. A microcomputer 7 detects the supply voltage and switches over the relay 8 according with the supply voltage. In the case that the dry battery 11 is used as the supply voltage, the 5V regulator 12 is selected, when the output voltage of the dry battery 11 is high and the 5V DC/DC converter 13 is selected when the output voltage of the dry battery 11 is low. In the case that the AC adaptor 2 is used as the supply voltage, the 5V regulator 12 is selected to obtain a high audio output 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a power supply circuit of an apparatus using an AC power supply and a battery as a power supply.

[0002]

2. Description of the Related Art A conventional technique will be described with reference to FIGS. In FIG. 2, the power supply circuit of the receiver 10 includes an AC adapter 2, a battery 3 to which a backflow prevention diode 4 is connected, and a series regulator 5. The output of the battery 3 to which the AC adapter 2 and the backflow prevention diode 4 are connected is input to the series regulator 5, converted into a constant DC voltage, and output. For example, as shown in FIG. 3, an AC adapter 2 and a backflow prevention diode 4 are provided.
6V is output by connecting four 1.5V dry batteries 11 connected in series. This 6V output is input to the 5V regulator 12, and is converted to a constant voltage of 5V. FIG. 6 shows a voltage drop characteristic 14 of the battery with respect to time. When a low drop type operable up to an input voltage of 5.16 V is used as the 5 V regulator 12, the power supply voltage is 6 V.
The equipment can be used from 0 hours to X hours from V to 5.16V.

FIG. 4 shows a conventional technique, which is used as a method for lowering a power supply voltage and operating a device continuously for a long time using a battery. Receiver 1
The power supply circuit 0 is composed of an AC adapter 2, a battery 3 to which a backflow prevention diode 4 is connected, and a DC / DC converter 5. The output of the battery 3 to which the AC adapter 2 and the backflow prevention diode 4 are connected is converted into a constant voltage by the DC / DC converter 13 and output. For example, as shown in FIG. 5, by connecting three or two 1.5 V batteries 11 connected to the AC adapter 2 and the backflow prevention diode 4 in series to 4.5 V,
Alternatively, 3 V is output. The 4.5 V or 3 V output is input to the 5 VDC / DC converter 13 and boosted to a constant voltage of 5 V. FIG. 7 shows a voltage drop characteristic 14 of the battery with respect to time. When a 5 VDC / DC converter 13 that can operate from an input voltage of 5.5 V to 1.1 V is used, a power supply voltage of 4.5 V or 3 V to 1.1 V can be used from 0 to Y hours. Becomes Further, since the number of batteries is 3 or 2 and 5 V can be output, it is used for lowering the power supply voltage and reducing the cost.

[0004]

However, in the above-mentioned prior art, when a battery is used and a 5V regulator is used as shown in FIG. 3, the input voltage of the 5V regulator is 5.
Since the operation is performed up to 16 V, as shown in the voltage drop characteristic 14 of the battery with respect to the time in FIG. 6, the operation time of the battery becomes 0 to X hours from 6 V to 5.16 V, which is not suitable for long-time continuous operation. There is a problem. Also,
When a DC / DC converter is used as shown in FIG. 5, it is suitable for long-time continuous operation using a battery. However, when an AC power supply is used, the fluctuation of the power supply voltage of the AC adapter is about twice as large and 3 V 5VDC /
The input voltage of the DC converter fluctuates up to 6V. Also, when using an AC adapter, a high power supply voltage is required to respond to requests such as increasing the audio output.
It is necessary to drive an audio amplifier using an AC adapter with a 6V output, but since a 5VDC / DC converter operates with an input voltage from 5.5V to 1.1V, the AC
When the adapter is used, there is a problem that it is impossible to use the 5VDC / DC converter.

The present invention solves these problems by using A
It is an object of the present invention to provide a power supply circuit capable of continuously operating a battery for a long time and increasing an audio output by an AC adapter in a device using a C adapter and a battery.

[0006]

According to the present invention, as shown in FIG. 1, the output of a battery connected to an AC adapter and a diode for preventing backflow is connected to one of the outputs of a battery via a relay. Series regulator, the other is D
Output by connecting to C / DC converter. This relay detects and controls the output of the AC adapter and the battery by a microcomputer or the like, so that when the output voltage is high or when the battery has a capacity, a series regulator is used and when the output voltage is low or the battery capacity is used. When there is no DC
/ DC converter.

As a result, when the device is operated using the battery, the voltage drop characteristic of the battery with respect to the time shown in FIG.
As shown in (2), the output voltage is detected by the microcomputer, and the relay is switched to the 5VDC / DC converter by the relay when the output voltage is reduced from 6V to 5.16V. 5VDC
/ DC converter input voltage is from 5.5V to 1.1V
, The battery can be used for 0 to Z hours from an output voltage of 6 V to 1.1 V, and the battery can be operated continuously for a long time. In addition, when the device is operated using an AC adapter, the output voltage is detected by a microcomputer, and a 5V regulator is used by a relay, so that an AC adapter having a high output voltage can be used, and a high audio output can be obtained. Is possible.

[0008]

An embodiment of the present invention will be described below with reference to FIGS. In FIG. 9, as a power source of the receiver 10, an output signal obtained by converting an AC signal supplied from an external AC power source into a direct current by the AC adapter 2 or a dry battery 11 to which a backflow prevention diode 4 is connected is used. One of the outputs is input to a 5 V regulator 12 and the other is input to a 5 VDC / DC converter 13 via a relay 8, and is converted into a constant voltage (for example, 5 V) and output. The relay 8 is controlled by the microcomputer 7 detecting the output voltage of the dry battery 11 to which the AC adapter 2 and the backflow prevention diode 4 are connected.

When the dry battery 11 is used as a power source, the microcomputer 7 detects the output voltage of the dry battery 11 and
As shown in the battery voltage drop 14 with respect to the time, from the input voltage of 6 V to 5.16 V, the relay 8 uses the 5 V regulator 12 to reduce the capacity of the dry battery 11,
5 VDC / DC operable from 5.5 V to 1.1 V at the relay 8 when the voltage drops to 5.16 V or less.
It switches to the converter 13 and outputs a constant voltage (5 V). Therefore, as shown in FIG. 8, it is possible to continuously operate the equipment from the power supply voltage of 6 V to 1.1 V for 0 hours to Z hours. When the AC adapter 2 is used as a power supply, the power supply voltage is detected by the microcomputer 7, and the 5V regulator 12 is selected by the relay 8, so that the AC adapter 2 having a high output voltage can be used. Higher audio output can be achieved.

In this embodiment, the means for boosting the input voltage is basically a DC / DC converter, and the means for decreasing the voltage is a series regulator. However, the present invention is not limited to this. The use of a booster circuit and a step-down circuit is possible.

[0011]

As described above, according to the present invention, A
In a device that uses a C power supply and a battery together, it is possible to provide a power supply circuit that is suitable for long-time continuous operation of the battery and that can select an AC adapter capable of increasing audio output.

[Brief description of the drawings]

FIG. 1 is a diagram showing an overall configuration of the present invention.

FIG. 2 is a diagram showing an example of the related art.

FIG. 3 is a diagram showing details of an example of the related art.

FIG. 4 is a diagram showing another conventional example.

FIG. 5 is a diagram showing details of another conventional example.

FIG. 6 is a graph showing an example of a conventional voltage drop characteristic of a battery with respect to time.

FIG. 7 is a graph showing another example of a voltage drop characteristic of a battery with respect to time in the related art.

FIG. 8 is a graph showing an example of a voltage drop characteristic of a battery with respect to time in the present invention.

FIG. 9 is a diagram showing an embodiment of the present invention.

[Explanation of symbols]

1. Power supply circuit 2. AC adapter
3 ... Battery 4 ... Backflow prevention diode 5 ... Series regulator 6 ... DC /
DC converter, 7 ... microcomputer, 8
... Relay, 9 ... Output, 10 ... Receiver, 11 ... Dry battery, 12 ... 5V regulator, 13 ... 5VDC / DC converter, 14 ...
Voltage drop characteristics of the battery over time.

Claims (2)

[Claims] 1. A power supply circuit for a device that uses an AC power supply and a battery as a power supply, comprising: a booster circuit for boosting an output of the power supply; a step-down circuit for decreasing the output of the power supply; and a booster circuit and a step-down circuit. A power supply circuit comprising: a switching circuit for switching; and a control circuit that detects an output voltage of the power supply and controls switching of the switching circuit according to the detected voltage. 2. The power supply circuit according to claim 1, wherein said step-up circuit is a DC / DC converter, and said step-down circuit is a series regulator.