JPH11122835A - Power-supply feeding adapter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To output a plurality of voltage vs. current characteristics from a power-supply feeding adapter, by inserting a small-power outputting circuit in between a secondary side of its transformer and its output terminal, and by changing over opportinuely the small-power outputting circuit into its large- power outputting circuit comprising a switching regulator through sensing the current values/voltage values of both the circuits. SOLUTION: In the case wherein the secondary battery of an electronic appliance is a lithium-ion battery, a 4.2 V sensing circuit 23 sends its sensed voltage value to a control circuit 28 and sends via a priority giving circuit 26 to a control circuit 27, when the output voltage of a power-supply feeding adapter exceeds 4.2 V. Hereupon, the control circuit 27 controls the switching operation of a transistor 9 in the output circuit of a diode 17 to output preferentially a small power. On the other hand, the control circuit 28 controls a pulse- width modulating circuit 29 correspondingly to the sensed current value of a current sensing circuit 15 and the sensed voltage value of the 4.2 V sensing circuit 23 to operate the switching transistor 30 and control a large power outputted by a diode 12. As a result, the output of the power-supply feeding adapter having a plurality of voltage vs. current characteristics can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to charging a secondary battery or supplying power to an electronic device, and more particularly to a power supply adapter having a plurality of output characteristics.

[0002]

2. Description of the Related Art Recently, portable telephones and camera-integrated VTs have been developed.
In portable electronic devices such as R, a secondary battery is used as a power source. When these electronic devices are used, it is necessary to charge a secondary battery with a power supply adapter (hereinafter, referred to as an AC adapter) prior to use.

A schematic diagram for charging a secondary battery included in an electronic device using an AC adapter will be described with reference to FIG. As shown in FIG. 9A, an AC adapter 112 having an outlet 111 is connected to a load resistor 113 such as a secondary battery of an electronic device.
And the secondary battery is charged according to the voltage and current characteristics shown in FIG. 9B.

FIG. 10 shows the configuration and characteristics of an AC adapter. One end of the primary side 121a of the conversion transformer is connected to the collector of the switching transistor 122, the emitter of the transistor 122 is grounded, and its base is connected to the pulse width modulation (Pulse Width Modulation) circuit 123. One end of the secondary side 121b of the conversion transformer is grounded, and the other end of the secondary side 121b is connected to the anode of the diode 124. A capacitor 125 is inserted between the cathode of the diode 124 and the ground.
A resistor 126 is inserted between the cathode of No. 4 and the output terminal 128. The resistor 126 is inserted between the two input terminals of the current detection circuit 127. The current value I ₁ detected by the current detection circuit 127 is supplied to one terminal of the switch 131, and the current value I ₂ is 131 is supplied to the other terminal.

The voltage detection circuit 1 is connected between the output terminal 128 and the ground.
29 is inserted, and the voltage detection circuit 129 detects a voltage output when the voltage exceeds V ₁ and V ₂ . The detected voltage value V ₁ is supplied to both terminals of the switch 131, and the voltage value V ₂ is supplied to the control circuit 130.
In the control circuit 130, control of the switch is performed based on the voltage value V ₁ supplied. In the control circuit 132, a current value I ₁ or the current value I ₂ from the current detection circuit 127,
The pulse width modulation circuit 123 is controlled based on the voltage value V ₂ from the voltage detection circuit 129. That is,
The output voltage is controlled according to the duty ratio output from pulse width modulation circuit 123. Voltage at that time,
The current characteristics were controlled only by detecting the voltage, as shown in FIG. 10B.

Therefore, as shown in FIG. 11A, when the AC adapter 141 is connected to the electronic device set 142 and the secondary batteries included in the set 142 are charged,
One that includes a communication unit 143 for communicating the state of charge of the secondary battery to the AC adapter 141 has been proposed.

[0007]

However, the AC adapter has been able to realize only one of the output characteristics shown in a section of the voltage and current characteristics shown in FIG. 11B. Furthermore, when charging a secondary battery, if a charging voltage and a charging current higher than the rated values are applied to the secondary battery, the secondary battery may be damaged.

For this reason, an electronic device must use an AC adapter having an output characteristic that matches the charging characteristics of a secondary battery included in the electronic device. There is a problem that it is necessary to have a plurality of AC adapters that match the charging characteristics of the battery.

Accordingly, an object of the present invention is to provide a power supply adapter having a plurality of output characteristics.

[0010]

According to the present invention, a first power supply circuit for outputting a first voltage and current characteristic and a second power supply circuit for outputting a second voltage and current characteristic are provided. And a first detecting means for detecting a current output from the first power supply circuit.
Current detection means, a second current detection means for detecting a current output from the second power supply circuit, a voltage detection means for detecting a voltage output from the first and / or second power supply circuit, Voltage dividing means for dividing a voltage detected by the voltage detecting means to give a priority to one of the first and second power supply circuits, a voltage divided by the voltage dividing means,
From the current detected by the first current detecting means, the first
Control means for controlling the power supply circuit of the first and second control means, and second control means for controlling the second power supply circuit from the voltage detected by the voltage detection means and the current detected by the second current detection means. And a power supply adapter.

[0011] A low power circuit for outputting a small power inserted between the secondary side of the conversion transformer and the output terminal, and a current inserted similarly between the secondary side of the conversion transformer and the output terminal A plurality of voltage and current characteristics are obtained by appropriately switching a switching regulator for outputting large power from the current value and the voltage value from the detection circuit and the voltage detection circuit based on the detected current value and / or voltage value. Can be output.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. In the description of this embodiment,
As an example, to charge a secondary battery of an electronic device,
Assume that an adapter is connected. Normally, in the case of a secondary battery, rated values are set for the voltage and current at the time of charging, and it is recommended that the secondary battery be charged with the voltage and current of the rated values. For example, in the case of a lithium ion battery of a certain type and capacity that has been widely used in recent years, the charging voltage is 4.2.
(V) or less, a charging current of 1 C (1 A) or less is determined as a rated value.

FIG. 1 shows the overall configuration of the first embodiment of the present invention. FIG. 1 shows a method of detecting current with a switching power supply. One end of the primary side 11a of the conversion transformer is connected to the collector of the switching transistor 30, the emitter of the transistor 30 is grounded, and its base is connected to the pulse width modulation circuit 29. One end of the secondary side 11b of the conversion transformer is grounded, and the other end of the secondary side 11b is connected to the secondary side 11c. The other end of the secondary side 11b is
Connected to the anode of diode 12. Diode 1
A capacitor 13 is inserted between the cathode of the second and ground and a resistor 14 is inserted between the cathode of the diode 12 and the output terminal 24. The resistor 14 is connected to a current detection circuit 15
The current value detected by the current detection circuit 15 is inserted between the two input terminals of the control circuit 28 and the output terminal 16.
Supplied to

The other end of the secondary side 11c of the conversion transformer is connected to the anode of a diode 17. A capacitor 18 is inserted between the cathode of the diode 17 and the ground, and the cathode of the diode 17 and the emitter of the transistor 19 are connected. This diode 17 and transistor 1
9 constitutes a small power circuit. Transistor 1
The resistor 20 is inserted between the collector of the transistor 9 and the output terminal 24, and the base of the transistor 19 is connected to the control circuit 27. The resistor 20 is inserted between two input terminals of the current detection circuit 21, and a current value detected by the current detection circuit 21 is supplied to the control circuit 27 and the output terminal 22.

A 4.2 V detection circuit 23 is inserted between the output terminal 24 and the ground. The 4.2 V detection circuit 23 detects the value when the output voltage exceeds 4.2 V. The detected voltage value is supplied to the control circuit 28 and the priority detection circuit 26.
Supplied to The priority detection circuit 26 gives priority to the transistor 19 via the control circuit 27 when the 4.2 V detection circuit 23 detects an output voltage of 4.2 V.

As shown in FIG. 1B, the small power output from the diode 17 and the transistor 19 is controlled by the control circuit 27 and is output with priority. Then, in the control circuit 28, the current value from the current detection circuit 15 and 4.2
The pulse width modulation circuit 29 is controlled based on the voltage value from the V detection circuit 23. Therefore, as shown in FIG. 1B, large power is output from the diode 12. That is, the output power is controlled in accordance with the duty ratio output from pulse width modulation circuit 29. As described above, a voltage higher than the reference output voltage is extracted from the switching output voltage, the priority can be detected, and the transistor 19 can be controlled so as to have an output characteristic as shown in FIG. 1B by controlling the transistor 19.

FIG. 2 shows the overall configuration of the second embodiment of the present invention. FIG. 2 shows a method for keeping the output power of the switching power supply safe. One end of the primary side 41 a of the conversion transformer is connected to the collector of the switching transistor 62, the emitter of the transistor 62 is grounded, and the base is connected to the pulse width modulation circuit 61.
One end of the secondary side 41b of the conversion transformer is grounded, and the other end of the secondary side 41b is connected to the secondary side 41c. Secondary side 41
The other end of b is connected to the anode of the diode 42.
A capacitor 43 is inserted between the cathode of the diode 42 and the ground, and a resistor 44 is inserted between the cathode of the diode 42 and the output terminal 52. The resistor 44 is inserted between two input terminals of the current detection circuit 45, and the current value detected by the current detection circuit 45 is supplied to the control circuit 60 via the switch 59.

The other end of the secondary side 41c of the conversion transformer is connected to the anode of the diode 46. A capacitor 47 is inserted between the cathode of the diode 46 and the ground, and the cathode of the diode 46 and the emitter of the transistor 48 are connected. This diode 46 and transistor 4
8 constitutes a small power circuit. Transistor 4
A resistor 49 is inserted between the collector of the transistor 8 and the output terminal 52, and the base of the transistor 48 is connected to the control circuit 57. The resistor 49 is inserted between the two input terminals of the current detection circuit 50. The current value detected by the current detection circuit 50 is transmitted to the control circuit 60 via the output terminal 51, the control circuits 57 and 58, and the switch 59. Supplied.

A 2V detection circuit 53 is provided between the output terminal 52 and the ground.
And a 4.2V detection circuit 54 are inserted in parallel. 2V
In the detection circuit 53, when the output voltage exceeds 2V, the value is detected, and the detected voltage value is supplied to the control circuit 58. The 4.2V detection circuit 54 detects the value when the output voltage exceeds 4.2V. The detected voltage value is supplied to the switch 59, the control circuit 60, and the priority detection circuit 56. The priority detection circuit 56 includes:
When the output voltage of 4.2 V is detected in the 2V detection circuit 54, the transistor 48
Priority.

As shown in FIG. 2B, the small power output from the diode 46 and the transistor 48 is controlled by the control circuit 57 and is output with priority. In the control circuit 58, the current value from the current detection circuit 50 and the 2V detection circuit 5
The switch 59 is switched on the basis of the voltage value (2 V) from No. 3. The signal selected by the switch 59 is supplied to the control circuit 60. In the control circuit 60, the pulse width modulation circuit 61 is controlled based on the voltage value from the 4.2V detection circuit 54 and the signal from the switch 59. Therefore, as shown in FIG. 2B, large power is output from the diode 42. That is, the power output according to the duty ratio output from the pulse width modulation circuit 61 is controlled.

Embodiments of output characteristics that can be controlled by applying the present invention are shown in FIGS. First,
According to the output characteristics shown in FIG. 3A, the V ₁ I _{1
The 1} I ₂ characteristic is switched and output. According to the output characteristics shown in FIG. 3B, V ₂ I ₁ characteristics and V ₂ I ₂ · V ₁
I ₂ characteristics are switched and output. According to the output characteristic shown in FIG. 4A, the V ₂ I ₁ · V ₁ I ₁ characteristic and the V ₂ I
_{The 2} · V ₁ I ₂ characteristic is switched and output. FIG. 4B
According to the output characteristic shown _{in, V 3 I 1 · V 2} I 1 characteristic, V
_{The 3} I ₂ · V ₁ I ₂ characteristic and the V ₃ I ₃ characteristic are switched and output. As shown in FIGS. 3 and 4, in this embodiment, the output of the AC adapter starts with a small power, so that an excessive current does not flow to the connection load.

The operation algorithm of the present invention will be described with reference to the flowchart of FIG. In step S1, AC
The adapter is controlled with low power. In step S2, the output voltage is detected. In step S3, it is determined whether or not the detected output voltage is equal to or lower than 2V. If it is determined that the output voltage is equal to or lower than 2V, the control shifts to step S4. In step S4, a circuit for switching the voltage and current characteristics is operated. In step S5, the output of the AC adapter is switched from low power to high power. In step S6, a current is detected. In step S7, it is determined whether or not the detected current is a small current. If it is determined that the detected current is a small current, the control proceeds to step S8. If it is determined that the current is not a small current, the process proceeds to step S8. The control moves to S6.
In step S8, the output of the AC adapter is switched from high power to low power, and control returns to step S1.

FIG. 6 shows the overall configuration of the third embodiment of the present invention. FIG. 3 shows a method in which a voltage and a current characteristic suitable for an electronic device can be output by switching a signal supplied to a pulse width control circuit by detecting a voltage and a current. One end of the primary side 71a of the conversion transformer is connected to the collector of the switching transistor 92, the emitter of the transistor 92 is grounded, and the base is connected to the pulse width modulation circuit 91. One end of the secondary side 71b of the conversion transformer is grounded, and the other end of the secondary side 71b is connected to the secondary side 71c. The other end of the secondary side 71b is
Connected to the anode of diode 72. Diode 7
A capacitor 73 is inserted between the cathode of the second and ground and a resistor 74 is inserted between the cathode of the diode 72 and the output terminal 83. The resistor 74 includes a current detection circuit 75
The current value detected by the current detection circuit 75 is inserted between the two input terminals of the control circuit 9 through the switch 89.
0.

The other end of the secondary side 71c of the conversion transformer is connected to the anode of the diode 76. A capacitor 77 is inserted between the cathode of the diode 76 and the ground, and a resistor 78 is inserted between the cathode of the diode 76 and the emitter of the transistor 81. The diode 76 and the transistor 81 form a small power circuit.
The collector of transistor 81 is connected to output terminal 83, and the base of transistor 81 is connected to control circuit 82. The resistor 78 is inserted between two input terminals of the current detection circuit 79, and the current value detected by the current detection circuit 79 is supplied to the switching circuit 80.

A voltage detecting circuit 84 is connected between the output terminal 83 and the ground.
And 86 are inserted in parallel. In the voltage detection circuit 84, when the output voltage exceeds a predetermined voltage, the value is detected.
5. The voltage detection circuit 86 detects a value when the output voltage exceeds a predetermined voltage. The detected voltage value is supplied to the switch 89 and the resistor 87. Resistors 87 and 88 are inserted in series between the output of voltage detection circuit 86 and ground. The midpoint potential (−ΔV) is extracted from the connection point between the resistors 87 and 88, and the control circuit 82
Supplied to

This midpoint potential (−ΔV) gives priority to the transistor 81. As shown in FIG. 6B, the small power output from the diode 76 and the transistor 81 is controlled by the control circuit 82 and is output with priority. The switch 89 is controlled by a control signal S1 from the switching circuit 80 and the switch switching circuit 85, and selects a current value from the detection circuit 75 or a voltage value from the voltage detection circuit 86. In the control circuit 90, the pulse width modulation circuit 91 is controlled based on the selected signal. Therefore, as shown in FIG.
Large power is output. That is, the power output according to the duty ratio output from pulse width modulation circuit 91 is controlled.

Switching of output characteristics which can be controlled by applying the present invention will be described with reference to FIG. According to the output characteristics shown in FIG. 7, the V ₂ I ₁ · V ₁ I ₂ characteristic and the V ₂ I ₂ characteristic are switched. As shown in FIG. 7A, the output characteristics operate in the order of a → b → c → d → e → f. When the current becomes f, the flow returns to a → b → c as shown in FIG. 7B. Thus, when the AC adapter operates with low power, as shown in FIG. 7B, a → b → c
Works with When the output of the AC adapter is switched from low power to high power and operates with high power, FIG.
As shown in FIG. The position f shown in FIG. 7 is set between the position a and the position b.

FIG. 8 shows an embodiment of an output characteristic which can be controlled by applying the present invention. According to the output characteristics shown in FIG. 8A, V ₃ I ₁ · V ₁ I ₂ characteristics, V ₂ I ₂ · V
₂ I ₄ properties, V ₃ I ₄ properties and _{V 4 I 4 · V 4 I} 3 characteristic is switched and output. According to the output characteristics shown in FIG. 8B, the V ₃ I ₁ · V ₁ I ₂ characteristic and the V ₂ I ₂ characteristic are switched and output. According to the output characteristics shown in FIG. 8C, V ₄ I ₁ · V ₁ I ₃ characteristics, V ₃ I ₃ characteristics, V ₄
The I ₁ · V ₂ I ₂ characteristic and the V ₄ I ₂ characteristic are switched and output.

In this embodiment, the description has been given of the case where the present invention is used for a charging method. However, the present invention is not limited to the charging method and may be used for a normally operating electronic device connected to an AC adapter. can do. For example, when an AC adapter is connected to listen to a radio broadcast of an operating cassette recorder with a radio and the cassette recorder is operated to record the radio broadcast on a cassette tape, When the load resistance of the electronic device connected to the adapter changes, the power output from the AC adapter can be switched from low power to high power and output by detecting the voltage and / or current flowing through the AC adapter. it can.

[0030]

According to the present invention, A which outputs a characteristic suitable for an electronic device or a charger by a method of detecting a voltage and / or a current and switching between small power and large power.
A C adapter can be realized. Thus, an AC adapter corresponding to a plurality of electronic devices or a plurality of chargers can be realized.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a first embodiment of an AC adapter according to the present invention.

FIG. 2 is a schematic diagram showing a second embodiment of the AC adapter of the present invention.

FIG. 3 is a schematic diagram illustrating an embodiment of voltage and current characteristics of the AC adapter according to the present invention.

FIG. 4 is a schematic diagram showing an embodiment of the voltage and current characteristics of the AC adapter of the present invention.

FIG. 5 is a flowchart showing an embodiment of the operation algorithm of the present invention.

FIG. 6 is a schematic diagram showing a third embodiment of the AC adapter of the present invention.

FIG. 7 is a schematic diagram showing an embodiment of the voltage and current characteristics of the AC adapter of the present invention.

FIG. 8 is a schematic diagram illustrating an embodiment of the voltage and current characteristics of the AC adapter according to the present invention.

FIG. 9 is a schematic diagram for explaining a conventional charging method.

FIG. 10 is a schematic diagram illustrating a conventional AC adapter.

FIG. 11 is a schematic diagram illustrating a conventional AC adapter.

[Explanation of symbols]

11 ... Conversion transformer, 12, 17 ... Diode, 13, 18 ... Capacitor, 14, 20, 25,
26: resistance, 15, 21: current detection circuit, 1
9, 30 ... transistor, 23 ... 4.2 V detection circuit, 27, 28 ... control circuit, 29 ... pulse width modulation circuit

Claims (3)

[Claims] 1. A first power supply circuit for outputting a first voltage and current characteristic, a second power supply circuit for outputting a second voltage and current characteristic, and a current output from the first power supply circuit First to detect
Current detecting means, and a second detecting means for detecting a current output from the second power supply circuit.
Current detecting means, voltage detecting means for detecting a voltage output from the first and / or second power supply circuit, and the voltage for giving priority to one of the first or second power supply circuit Voltage dividing means for dividing the voltage detected by the detecting means; the voltage divided by the voltage dividing means;
A first control unit for controlling the first power supply circuit from the current detected by the current detection unit; a voltage detected by the voltage detection unit;
From the current detected by the current detecting means of
And a second control unit for controlling the power supply circuit. 2. The first voltage detecting means according to claim 1, wherein said voltage detecting means detects a first predetermined voltage of a voltage output from said first and / or second power supply circuit. And second predetermined voltage detecting means for detecting a second predetermined voltage lower than the first predetermined voltage of the voltage output from the first and / or second power supply circuit. Power supply adapter. 3. The power supply circuit according to claim 1, wherein the second power supply circuit includes: a pulse width modulation unit; and a switch unit that is turned on / off based on a duty ratio of a pulse signal output from the pulse width modulation unit. And a power supply adapter.