JPS63133841A - Electric source circuit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention provides a solution for reducing the voltage drop of the primary power supply due to a power outage, etc.
This invention relates to a power supply circuit that connects a secondary battery power source and continues its operation.

[Conventional technology]

BACKGROUND ART Conventionally, power supply circuits have been widely used that prepare a secondary battery power source in the event of a power outage of a primary power source such as a commercial power source, and can instantly switch from operation using the primary power source to operation using the secondary battery power source.

FIG. 3 is an example of a conventionally used power supply circuit. In the figure, l is an input terminal that serves as an input part for DC voltage generated from a commercial power supply, 2 is an output terminal for supplying DC voltage to a load (not shown), 3 is a battery, 4 is a constant voltage diode, and 5 is a voltage regulator diode. NP N ) transistor, 6 and 7 are diodes, 8 is a PNP transistor, and R1-R3 are resistors. The Zener voltage of the constant voltage diode 4 is the voltage of the battery 3.
The voltage value of the battery 3 is set lower than the rated value of the DC voltage applied to the input terminal 1.

That is, when the rated DC voltage is applied to input terminal 1,
The constant voltage diode 4 becomes conductive due to the DC voltage higher than its Zener voltage, and as a result, the transistor 5
turns on. As a result, resistor R3, diode 6,
A current flows through the path between the resistor R1 and the transistor 5, and the base voltage generated at the connection point between the cathode of the diode 6 and the resistor R1 is applied to the transistor 8. Here, the voltage value of the battery 3 applied to the emitter of the transistor 8 is set lower than the base voltage input at this time,
Therefore, the off state of transistor 8 is maintained. That is, when the rated DC voltage is applied to the input terminal 1, the battery 3 is not connected to the output terminal J terminal 2, and the DC voltage via the input terminal 1 is supplied from the output terminal 2. become.

In the power supply circuit configured in this way, when the DC voltage applied to the input terminal 1 decreases and becomes lower than the voltage value of the battery 3 due to a power outage or the like, the base voltage of the transistor 8 becomes lower than the emitter voltage. , the current flow in the path of resistor R3 and diode 6 is interrupted, and transistor 5 is connected to battery 3. Transistor 8. Current begins to flow through the path of resistor R1, and transistor 8 is turned on. Further, since a voltage higher than the Zener voltage is applied to the constant voltage diode 4 by the battery 3 via the transistor 8, the transistor 5 is maintained in an on state, and thereby the transistor 8 is kept in an on state. . In this way, when the DC voltage from the input terminal 1 drops due to a power outage, etc., the battery 3 is automatically connected to the output terminal 2, and the DC voltage is supplied from the output terminal 2 without momentary interruption. .

By the way, after the battery 3 is connected to the output terminal 2 in this manner, if the voltage supply to the load is continued, the voltage of the battery 3 will decrease as the charge is discharged.

That is, when the voltage of the battery 3 drops below the Zener voltage of the voltage regulator diode 4, the voltage regulator diode 4 becomes non-conductive, the transistor 5 turns off, and the transistor 8 turns off accordingly. In other words, when the voltage of the battery 3 drops below the Zener voltage of the voltage regulator diode 4,
The connection of the battery 3 to the output terminal 2 is automatically disconnected, and the supply of battery voltage via the output terminal 2 is interrupted.

It goes without saying that when the supply of the rated DC voltage to the input terminal 1 is resumed (when the power outage is restored), the initial operating state is restored in this power supply circuit.

[Problem that the invention seeks to solve]

However, such a conventional power supply circuit has a problem in that it is not possible to know whether or not the automatic disconnection operation of the battery 3 from the output terminal 2 has been performed after the power is restored. For example, if a load including a memory element, etc. is connected to the output terminal 2, the memory contents may be destroyed by the automatic disconnection operation of the battery 3. In order to recognize the presence or absence of damage to the power supply battery, it is important to know whether the power supply battery is automatically disconnected after the power outage is restored.

[Means for solving problems]

The present invention has been made in view of these problems, and is designed to memorize the presence or absence of a disconnection operation of the secondary battery power source when the voltage of the primary power source drops.

[Effect]

Therefore, according to the present invention, it is possible to know whether or not the secondary battery power source is disconnected when the voltage of the primary power source drops, when the voltage of the primary power source is restored.

〔Example〕

Hereinafter, the power supply circuit according to the present invention will be explained in detail.

FIG. 1 is a circuit diagram showing one embodiment of this power supply circuit. In this figure, the same reference numerals as in FIG. 3 indicate the same constituent elements, and the explanation thereof will be omitted. In the figure, 9 is a flip-flop circuit, and 10 to 13 are diodes. The Q output of flip-flop circuit 9 is connected to the cathode of diode 10, and the anode of diode 10 is connected to the anodes of diodes 6 and 11. Then, the cathode of the diode 11 is connected to N through the resistor R5.
It is connected to the base of a PNI transistor 51, and a series circuit of a constant voltage diode 4 and a resistor R2 is connected between the base of this transistor 51 and the collector of the transistor 8. In addition, a diode 1 is connected to the output terminal 2.
The collector of the transistor 8 is connected through the input terminal 1 and the collector of the transistor 51, and a series circuit of a resistor R4 and a diode 12 is connected between the input terminal 1 and the collector of the transistor 51.

An information output terminal 14 is led out from the connection point between the resistor R4 and the diode 12. The flip-flop circuit 9 is supplied with a DC voltage as a power supply voltage via the input terminal 1, and the flip-flop circuit 9 automatically resets its operation when this power supply voltage is applied. There is.

Next, the operation of the power supply circuit configured as described above will be explained. That is, while the rated DC voltage is being applied to the input terminal 1, the device control section or the like (not shown) sets the flip-flop circuit 9 to the set state. As a result, the Q output of the flip-flop circuit 9 becomes rHJ level,
The diode 10 becomes non-conductive, the diode 11 becomes conductive, and the transistor 51 is turned on, so that current flows through the path of the resistor R3, diode 6, resistor R1, and transistor 51. At this time, the voltage applied to the base of transistor 8 is higher than the voltage value of battery 3, so
Transistor 8 remains off. That is, when the rated DC voltage is applied to the input terminal 1, the battery 3 is not connected to the output terminal 2, and the DC voltage via the input terminal 1 is supplied from the output terminal 2. .

In addition, when the DC voltage from input terminal 1 decreases and becomes lower than the voltage value of battery 3 due to a power outage, etc., transistor 8
Since the base voltage of battery 3. Transistor 8. Current begins to flow through the path of resistor R1, and transistor 8
turns on. As a result, a voltage higher than the Zener voltage of the voltage regulator diode 4 is applied to the battery 3 via the transistor 8.
is applied, the transistor 51 is maintained in the on state, and the transistor 8 is maintained in the on state. In this way, when the DC voltage from the input terminal 1 drops due to a power outage, etc., the battery 3 is automatically connected to the output terminal 2, and the DC voltage is supplied from the output terminal 2 without momentary interruption. .

Furthermore, when the voltage of the battery 3 drops below the Zener voltage of the voltage regulator diode 4 as the charged charge is discharged, the voltage regulator diode 4 becomes non-conductive, the transistor 51 turns off, and accordingly the transistor 8 turns off. Become. As a result, the connection of the battery 3 to the output terminal 2 is automatically disconnected, and the supply of battery voltage via the output terminal 2 is interrupted.

On the other hand, when the supply of the rated DC voltage to the input terminal 1 is resumed (when the power outage is restored), the flip-flop circuit 9 is automatically reset and its Q output becomes "L" level.

As a result, diode 10 becomes conductive, and the flow of current through diode 6 and diode 11 is interrupted. Here, looking at the on/off state of the transistor 51 before the supply of rated DC voltage to the input terminal 1 is resumed, it is found that the voltage value of the battery 3 is maintained at or above the Zener voltage of the voltage regulator diode 4. In this case, that is, when the battery 3 is automatically connected to the output terminal 2, the transistor 51 is in an on state. Furthermore, when the voltage value of the battery 3 becomes lower than the Zener voltage of the voltage regulator diode 4, that is, when the battery 3 is automatically disconnected from the output terminal 2, the L transistor 51 It is in the off state. In other words, the diode 6 and the diode 11 become non-conductive, so that the DC voltage via the input terminal 1 is applied to the transistor 8 and the transistor 5.
1, and does not act on the base of transistor 51.1. Resistor R1,
Transistor 8. Since a closed loop is formed by the resistor R2 and the voltage regulator diode 4, the transistor 51 is turned on and off.
The off state maintains the state at the time of power outage. Therefore, the on/off state of this transistor 51 is determined by the information output terminal 14.
By knowing through
It is possible to recognize whether or not an automatic disconnection operation has been performed. That is, if the information output terminal 14 has a high potential, it can be determined that the automatic disconnection operation of the battery 3 was performed during a power outage.

In a power supply circuit that performs such an operation, the transistor 51 can be called a transistor for automatic disconnection control and operation storage of the battery 3.

It should be noted that the clip-flop circuit can be implemented in the same manner by using a general-purpose microcomputer IC having a built-in flip-flop function. An example in this case is shown in FIG. In the figure, 15 is a Baud IC called 8234, which uses a transistor 16 to invert the logic output polarity of the reset when the power is turned on.

〔Effect of the invention〕

As explained above, according to the power supply circuit according to the present invention, the presence or absence of a disconnection operation of the secondary battery power supply when the voltage of the primary power supply drops is memorized. It is possible to know whether the next battery power source is disconnected or not, and extremely effective effects such as being able to recognize whether memory contents are destroyed during a power outage can be expected.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of a power supply circuit according to the present invention, and FIG. 2 is a circuit diagram showing an example in which a clip-flop circuit in this power supply circuit is configured with a general-purpose microcomputer IC having a built-in flip-flop function. , FIG. 3 is a circuit diagram showing a conventional power supply circuit. 1...Input terminal, 2...Output terminal, 3...Battery,
4... Constant voltage diode, 8... PNP transistor, 9... Flip-flop circuit, 14... Information output terminal, 51... NPN transistor.

Claims (1)

[Claims] In a power supply circuit that automatically connects a secondary battery power source when the voltage of the primary power source drops, and automatically disconnects the battery power source when the voltage of the secondary battery power source drops, A power supply circuit characterized in that it is provided with a storage means for storing whether or not a battery power supply disconnection operation is performed.