JPH11318028A - Dc power supply device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a DC power supply device which is capable of applying a voltage which does not exceed a set value to a circuit as a DC power supply device which does not have a remote sensing function even if a voltage monitor line is open-circuited, while a power is supplied to the circuit and can check whether the voltage monitor line is an open-circuited or not before a power is supplied to the circuit. SOLUTION: A resistor R1 is connected between a plus side output terminal 4p and a plus side sensing terminal 5p, a resistor R2 is connected between a minus side output terminal 4m and a negative side sensing terminal 5m and a series circuit, consisting of a resistor R3 and a switch S1 is connected between the plus side sensing terminal 5p and the minus side sensing terminal 5m. In a normal use state, a switch S1 is opened. At the checking of the switch S1 is closed. At that time, if a plus side voltage monitor line is open-circuited, the output voltage ofa n operational amplifier 11 is R3×Vo/(R1+R2). If a negative side voltage monitor line 3m is open-circuited, the output voltage of the operational amplifier 11 is R3×Vo/(R2+R3).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a DC power supply having a remote sensing function.

[0002]

2. Description of the Related Art A direct current power supply used in various electronic circuits and battery charging circuits. When an accurate voltage is applied to a certain point, a voltage monitor line is provided separately from a power supply line, and a cable or board pattern is provided. The remote sensing is used to monitor the voltage in a state where the voltage drop due to the resistance is canceled.

FIG. 7 shows an example of a conventional DC power supply having such a remote sensing function. This DC power supply device has a plus side connection terminal 1p and a minus side connection terminal 1m connected to a circuit such as a battery, and the plus side connection terminal 1p connects a plus side power supply line 2p and a plus side voltage monitor line 3p. Is connected to the plus side output terminal 4p and the plus side sensing terminal 5p, and the minus side connection terminal 1m is connected to the minus side output terminal 4m and the minus side via the minus side power supply line 2m and the minus side voltage monitor line 3m. Connected to sensing terminal 5m.

The source of a MOS transistor 17 as a control element is connected to the plus side output terminal 4p, and the power supply voltage Vcc is supplied to the plus side output terminal 4p via the drain / source of the transistor 17.

The voltage obtained at the plus side sensing terminal 5p via the plus side voltage monitor line 3p is:
The voltage supplied to the non-inverting input terminal of the operational amplifier 11 and obtained at the negative sensing terminal 5m via the negative voltage monitor line 3m is supplied to the inverting input terminal of the operational amplifier 11, and the output voltage of the operational amplifier 11 is Is supplied to the inverting input terminal of the operational amplifier 12 and is compared with the set voltage Vset1 supplied to the non-inverting input terminal. The output side of the operational amplifier 12 is connected via the diode 13 to the gate of the transistor 17.

The voltage obtained at the plus side output terminal 4p is supplied to the non-inverting input terminal of the operational amplifier 14, and the voltage obtained at the minus side output terminal 4m is supplied to the operational amplifier 1
4, the output voltage of the operational amplifier 14 is supplied to the inverting input terminal of the operational amplifier 15, and is compared with the set voltage Vset2 supplied to the non-inverting input terminal. The set voltage Vset2 is for overvoltage protection,
t2> Vset1. The output side of the operational amplifier 15 is connected to the gate of the transistor 17 via the diode 16.

In this DC power supply, the voltage between the plus side sensing terminal 5p and the minus side sensing terminal 5m falls below the set voltage Vset1 and the diode 13
Is off and transistor 17 is on,
A voltage is applied to a circuit such as a battery, and power is supplied.

When the voltage between the plus output terminal 4p and the minus output terminal 4m exceeds the set voltage Vset2 for overvoltage protection, the diode 16 turns on,
Since the transistor 17 is turned off, an overvoltage exceeding the set voltage Vset2 is not applied to a circuit such as a battery.

[0009]

However, in the conventional DC power supply shown in FIG. 7, if the plus side voltage monitor line 3p or the minus side voltage monitor line 3m breaks during the supply of power to the circuit. No voltage is applied to the circuit or the set voltage V for overvoltage protection
A high voltage up to set2 may be applied to the circuit.

That is, in the conventional DC power supply device shown in FIG. 7, when the plus side voltage monitor line 3p or the minus side voltage monitor line 3m is disconnected, the output voltage of the operational amplifier 11 becomes unstable, and the diode 13 is turned on.
In some cases, the transistor 17 is turned off and no voltage is applied to the circuit. Conversely, when the diode 13 is turned off and the transistor 17 is turned on, the circuit continues until the voltage between the plus output terminal 4p and the minus output terminal 4m exceeds the set voltage Vset2 for overvoltage protection. May be applied with a high voltage.

Further, in the conventional DC power supply of FIG.
It is not possible to check whether the plus side voltage monitor line 3p or the minus side voltage monitor line 3m is broken, and it is not possible to check whether the plus side voltage monitor line 3p or the minus side voltage monitor line 3m is broken. .

Therefore, the present invention firstly provides a DC power supply having no remote sensing function even if the voltage monitor line is disconnected during the power supply to the circuit so that the circuit does not exceed the set value. The voltage is applied.

The present invention provides, in addition to the first, whether or not the voltage monitor line is disconnected, and, if the voltage monitor line is disconnected, which of the plus side voltage monitor line and the minus side voltage monitor line Can be checked in advance before the power is supplied to the circuit.

[0014]

According to the first aspect of the present invention, a positive output terminal connected to a positive power supply line and a positive sensing terminal connected to a positive voltage monitor line are connected. 1, a negative output terminal connected to the negative power supply line,
A second resistor is connected between the negative side sensing terminal connected to the negative side voltage monitor line.

According to a second aspect of the present invention, in addition to the first aspect, a series circuit of a third resistor and a switch is connected between the positive sensing terminal and the negative sensing terminal.

According to a third aspect of the present invention, in the second aspect, a fuse is further connected to the plus side output terminal or the minus side output terminal.

In the DC power supply according to the first aspect of the present invention, if the positive side voltage monitor line is not disconnected to the positive side sensing terminal during power supply to the circuit, When the terminal voltage is applied through the positive side voltage monitor line and the positive side voltage monitor line is disconnected, the voltage of the plus side output terminal is applied through the first resistor, and the minus side sensing terminal is connected to the minus side sensing terminal. If the voltage monitor line is not broken,
The negative terminal voltage of the circuit is applied via the negative voltage monitor line, and when the negative voltage monitor line is disconnected, the voltage of the negative output terminal is applied via the second resistor.

Therefore, even if the plus side voltage monitor line or the minus side voltage monitor line is broken during the supply of power to the circuit, the plus side output terminal and the minus side sensing terminal are connected between the plus side sensing terminal and the minus side sensing terminal. The voltage between the positive side voltage output terminal and the negative side voltage monitor line is the same as the state without the remote sensing function by the positive side voltage monitor line and the negative side voltage monitor line, and a voltage that does not exceed the set value is applied to the circuit. Become like

In the DC power supply device according to the second aspect of the present invention, during normal use of supplying power to the circuit, the switch is turned off, and the third resistor is not connected between the plus side sensing terminal and the minus side sensing terminal. At the time of checking before supplying power to the circuit, the switch is turned on, and the third resistor is connected between the plus side sensing terminal and the minus side sensing terminal.

In this case, the first, second, and third resistors are represented by R
When the voltage Vo is applied to the positive output terminal and the negative output terminal is set to 0 V (ground potential), the positive voltage monitor line is disconnected and the negative voltage monitor line is disconnected. Otherwise, the negative sensing terminal is at the same 0 V as the negative output terminal via the negative power supply line and the negative voltage monitor line, so the positive sensing terminal is connected to the resistors R1 and R3 of the voltage Vo. By division,
R3 × Vo / (R1 + R3), and the voltage Vx between the positive sensing terminal and the negative sensing terminal
Vx = R3 × Vo / (R1 + R3) (1)

Conversely, when the plus side voltage monitor line is not broken and the minus side voltage monitor line is broken, the plus side sensing terminal is connected via the plus side power supply line and the plus side voltage monitor line. ,
Since the voltage Vo becomes the same as the positive output terminal, the negative sensing terminal becomes R2 × Vo / (R2 + R3) by dividing the voltage Vo by the resistors R3 and R2. Vx = R3 × Vo / (R2 + R3) (2)

When both the positive voltage monitor line and the negative voltage monitor line are disconnected,
By dividing the voltage Vo by the resistors R1, R3, and R2,
The positive sensing terminal is (R2 + R3) Vo / (R
1 + R2 + R3), the negative sensing terminal is R2 × Vo / (R1 + R2 + R3), and the voltage Vx between the positive sensing terminal and the negative sensing terminal is Vx = R3 × Vo / (R1 + R2 + R3) (3) Become.

Further, when neither the plus side voltage monitor line nor the minus side voltage monitor line is disconnected, the plus side sensing terminal has the same voltage Vo as the plus side output terminal, and the minus side sensing terminal has the minus side output terminal. And the voltage Vx between the plus side sensing terminal and the minus side sensing terminal.
Vx = Vo (4)

Therefore, power is supplied to the circuit to determine whether or not the voltage monitor line is disconnected, and if so, which of the plus side voltage monitor line and the minus side voltage monitor line is broken. You can check before you do.

In the DC power supply device according to the third aspect of the present invention, at the time of checking before supplying power to the circuit, if the fuse is disconnected, the plus side sensing is performed regardless of whether the voltage monitor line is disconnected. Since the voltage Vx between the terminal and the negative sensing terminal is 0 V, it is possible to check in advance whether or not the fuse is disconnected, in distinction from the disconnection of the voltage monitor line.

[0026]

FIG. 1 shows an embodiment of a DC power supply according to the present invention.

In this embodiment, the plus side output terminal 4p
And a plus side sensing terminal 5p, a resistor R1 is connected between the minus side output terminal 4m and the minus side sensing terminal 5m, and a resistor R2 is connected between the plus side sensing terminal 5p and the minus side sensing terminal 5m. , A series circuit of a resistor R3 and a switch S1 is connected between the positive output terminal 4p and a connection point between the source of the MOS transistor 17 as a control element and the non-inverting input terminal of the operational amplifier 14. , And fuse F1. Others are the same as the conventional DC power supply device shown in FIG.

However, the resistors R1 and R2 are connected to the operational amplifier 1
1 and sufficiently higher than the impedance of the voltage monitor lines 3p and 3m.

In the DC power supply of this embodiment, during normal use for supplying power to a circuit such as a battery connected between the plus side connection terminal 1p and the minus side connection terminal 1m,
As shown in FIG. 1, the switch S1 is turned off so that the resistor R3 is not connected between the positive sensing terminal 5p and the negative sensing terminal 5m. In normal use, Vset2> Vset1.

In this case, the positive voltage monitor line 3p
If both the negative voltage monitor line 3m and the negative voltage monitor line 3m are not disconnected, as in the conventional DC power supply device of FIG.
Is applied to a circuit such as a battery and power is supplied in a range where the diode 13 is turned off and the transistor 17 is turned on. The voltage between the positive output terminal 4p and the negative output terminal 4m is equal to the set voltage V for overvoltage protection.
When the voltage exceeds set2, the diode 16 turns on and the transistor 17 turns off, so that an overvoltage exceeding the set voltage Vset2 is not applied to a circuit such as a battery.

If the plus side voltage monitor line 3p or the minus side voltage monitor line 3m is disconnected while the power is being supplied to the circuit, and if the plus side voltage monitor line 3p is disconnected, the plus side sensing terminal 5p is connected to the plus side output terminal. When the voltage of 4p is applied via the resistor R1 and the negative voltage monitor line 3m is disconnected, the voltage of the negative output terminal 4m is applied to the negative sensing terminal 5m via the resistor R2.

Therefore, even when the plus side voltage monitor line 3p or the minus side voltage monitor line 3m is disconnected during the supply of power to the circuit, the plus side sensing terminal 5p and the minus side sensing terminal 5m are connected between the plus side sensing terminal 5p and the minus side sensing terminal 5m. A voltage between the output terminal 4p and the negative output terminal 4m is obtained, and the state becomes the same as the state without the remote sensing function by the positive voltage monitor line 3p and the negative voltage monitor line 3m. A voltage not exceeding Vset1 is applied.

At the time of checking before supplying power to the circuit, the switch S1 is turned on, and a resistor R is connected between the plus side sensing terminal 5p and the minus side sensing terminal 5m.
3 is connected. At the time of checking, the plus side power supply line 2p and the minus side power supply line 2m are connected to the plus side voltage monitor line 3p and the minus side voltage monitor line 3m, respectively. , Vset1> Vset2.

In this case, the voltage V is applied to the positive output terminal 4p.
When o is applied and the negative output terminal 4m is set to 0V (ground potential), the positive voltage monitor line 3p is disconnected and the negative voltage monitor line 3m Is not disconnected, the negative side sensing terminal 5m is at the same 0 V as the negative side output terminal 4m via the negative side power supply line 2m and the negative side voltage monitor line 3m, so that the positive side sensing terminal 5p is Resistors R1 and R of voltage Vo
The division by 3 gives R3 × Vo / (R1 + R3), and the voltage between the plus sensing terminal 5p and the minus sensing terminal 5m, that is, the output voltage Vx of the operational amplifier 11, is given by: Vx = R3 × Vo / (R1 + R3) ... (1)

Conversely, as shown in FIG. 3, when the plus side voltage monitor line 3p is not broken and the minus side voltage monitor line 3m is broken, the plus side sensing terminal 5p is connected to the plus side power supply. Since the voltage Vo becomes the same as that of the plus output terminal 4p via the line 2p and the plus voltage monitor line 3p, the minus sensing terminal 5m is divided by the resistors R3 and R2 into R2 × Vo / (R2 + R3). ), And the positive sensing terminal 5p and the negative sensing terminal 5m
, Ie, the output voltage Vx of the operational amplifier 11
Vx = R3 × Vo / (R2 + R3) (2)

As shown in FIG. 4, when both the positive side voltage monitor line 3p and the negative side voltage monitor line 3m are disconnected, the resistances R1, R
3, the plus side sensing terminal 5p becomes (R2 + R3) Vo / (R1 + R2 + R3), and the minus side sensing terminal 5m becomes R2 × Vo /
(R1 + R2 + R3), and the voltage between the plus side sensing terminal 5p and the minus side sensing terminal 5m, that is, the output voltage Vx of the operational amplifier 11, is as follows: Vx = R3 × Vo / (R1 + R2 + R3) (3)

Further, when neither the plus side voltage monitor line 3p nor the minus side voltage monitor line 3m is disconnected, the plus side sensing terminal 5p becomes the same voltage Vo as the plus side output terminal 4p, and the minus side sensing terminal 5m becomes , Which is the same 0 V as the negative output terminal 4m, so that the voltage between the positive sensing terminal 5p and the negative sensing terminal 5m, that is, the operational amplifier 1
The output voltage Vx of 1 is as follows: Vx = Vo (4)

As shown in FIG. 5, when the fuse F1 is disconnected, the positive side voltage monitor line 3p
Or, the plus side sensing terminal 5p and the minus side sensing terminal 5m become 0V regardless of whether the minus side voltage monitor line 3m is disconnected or not, and the plus side sensing terminal 5p and the minus side sensing terminal 5m.
, Ie, the output voltage Vx of the operational amplifier 11
Becomes 0V.

FIG. 6 is a table showing the above situation. As is clear from the above, according to the above-described embodiment, it is determined whether or not the plus side voltage monitor line 3p or the minus side voltage monitor line 3m is disconnected by the output voltage Vx of the operational amplifier 11, and the disconnection is performed. If it is, which of the plus side voltage monitor line 3p and the minus side voltage monitor line 3m is disconnected is determined.
The fuse F1 can be checked in advance and distinguished from the disconnection of the voltage monitor lines 3p and 3m.
It is possible to check in advance whether or not is disconnected.

In the embodiment of FIG. 1, the set voltage Vse
In the case where overvoltage protection is performed by t2, the power supply voltage V
When a stabilized cc is used, it is not necessary to perform overvoltage protection using the set voltage Vset2. In such a case, the above-described disconnection check is performed by setting the set voltage Vset1 higher than the power supply voltage Vcc. Can be.

[0041]

As described above, according to the first aspect of the present invention, even if the voltage monitor line is disconnected during the supply of power to the circuit, the DC power supply having no remote sensing function can be used as a circuit. , A voltage not exceeding the set value is applied.

According to the second aspect of the present invention, it is further determined whether or not the voltage monitor line is disconnected. If the voltage monitor line is disconnected, which of the plus side voltage monitor line and the minus side voltage monitor line is disconnected. Can be checked before supplying power to the circuit.

According to the third aspect of the present invention, whether or not the fuse is disconnected can be checked in advance before supplying power to the circuit, in distinction from the disconnection of the voltage monitor line.

[Brief description of the drawings]

FIG. 1 is a diagram showing one embodiment of a DC power supply device of the present invention.

FIG. 2 is a diagram showing a state at the time of a check when a positive-side voltage monitor line is disconnected.

FIG. 3 is a diagram showing a state at the time of a check when a negative voltage monitor line is disconnected.

FIG. 4 is a diagram showing a state at the time of a check when both the positive side voltage monitor line and the negative side voltage monitor line are disconnected.

FIG. 5 is a diagram showing a state at the time of checking when a fuse is disconnected.

FIG. 6 is a diagram showing a state at the time of a check in a table.

FIG. 7 is a diagram illustrating an example of a conventional DC power supply device.

[Explanation of symbols]

1p: plus side connection terminal, 1m ... minus side connection terminal,
2p ... plus side power supply line, 2m ... minus side power supply line, 3p ... plus side voltage monitor line, 3m ...
Minus side voltage monitor line, 4p ... plus side output terminal, 4m ... minus side output terminal, 5p ... plus side sensing terminal, 5m ... minus side sensing terminal, R1 ... first resistor, R2 ... second resistor, R3 ... Third resistance, S1
... Switch, F1 ... Fuse

Claims (3)

[Claims] A first resistor is connected between a positive output terminal connected to a positive power supply line and a positive sensing terminal connected to a positive voltage monitor line, and a negative power supply is provided. A DC power supply device in which a second resistor is connected between a negative output terminal connected to the line and a negative sensing terminal connected to the negative voltage monitor line. 2. The DC power supply according to claim 1, wherein a series circuit of a third resistor and a switch is connected between the plus side sensing terminal and the minus side sensing terminal. 3. The DC power supply device according to claim 2, wherein a fuse is connected to said positive output terminal or said negative output terminal.