JPH049020B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a voltage drop detection circuit for a backup battery, and more particularly to a circuit for detecting an output voltage drop of a battery for backing up a storage device.

(Prior Art) FIG. 2 is a circuit diagram showing a conventional backup battery voltage drop detection circuit. In the same figure,
1 is a power supply control circuit, 2 is a backup battery, 3 is a
is a voltage detection IC, 4 is a light emitting diode, 5 is a driver for driving the light emitting diode, 6 is a variable resistor, 7
is a diode, 8 is a power input terminal, 9 is a reference voltage input terminal, and 10 is a voltage output terminal. The power supply input terminal 8 is connected to the input side of the power supply control circuit 1 . The output side of the power supply control circuit 1 is connected to the anode of the diode 7 and the voltage output terminal 10 . The reference voltage input terminal 9 is connected to the cathode of the diode 7, the positive electrode of the backup battery 2, and one end (b) of the variable resistor 6. The negative electrode of the backup battery 2 is grounded. The output side of the voltage detection IC 3 is connected to the anode of the light emitting diode 4 via the light emitting diode driver 5. Further, the input side of the voltage detection IC 3 is connected to the a side, which is the other end of the variable resistor 6, and is grounded via the resistor.
Note that the +5V power supplied to the power input terminal 8 is supplied to all storage devices (not shown) including this circuit. In addition, when +5V is supplied to the power input terminal 8, the power supply control circuit 1
This circuit supplies power to 0 and prevents current from the backup battery 2 from flowing to the voltage output terminal 10 when +5V is not supplied. Furthermore, the voltage detection IC 3 is one such as ICL8211 manufactured by Intersil Corporation, which has a threshold transition voltage that varies from 0.98V to 1.19V. When the voltage of the backup battery 2 drops, the variable resistor 6 receives a predetermined voltage (hereinafter referred to as
(referred to as alarm voltage).
This is for adjusting the operation of IC3.

The operation of the conventional example having the above configuration will be described below.

First, the procedure for setting the alarm voltage so that the light emitting diode 4 lights up when the voltage falls below the alarm voltage is performed as follows. First, the variable resistor 6 is moved in the direction a, and the backup battery 2 is
Without removing +5V from the power supply input terminal 8, a reference voltage is applied to the reference voltage input terminal 9 such that the voltage at the voltage output terminal 10 of the backup battery 2 reaches the alarm voltage value. In that state, +
When applying 5V to the power supply control circuit 1 and changing the variable resistor 8 in the direction from a to b, when the voltage at point α reaches the threshold transition voltage of the voltage detection IC 3, the voltage detection IC 3 changes. The output level changes from high to low and the light emitting diode 4 lights up.
At this point, the variable resistor 6 is fixed, and the reference voltage applied to the reference voltage input terminal 9 is removed.

During operation, a backup battery 2 is attached and used. During operation, when the output voltage of the backup battery 2 falls below the alarm voltage, the light emitting diode 4 lights up to notify that it is time to replace the battery.

(Problems to be Solved by the Invention) However, in the conventional circuit described above, due to an abnormality in the storage device connected to the voltage output terminal 10 or an abnormality in the backup battery 2, the output voltage temporarily drops below the alarm voltage. In this case, the light emitting diode 4 is turned on temporarily, but then turned off, and even if storage data is destroyed, there is a problem in that it is impossible to determine whether or not the cause is due to the power supply system. In addition, it is not possible to easily check whether the light emitting diode 4 is broken and does not light up, and there is a problem that an alarm is not displayed even if the output voltage falls below the alarm voltage.

The present invention is intended to solve these problems, and an object of the present invention is to provide a highly reliable backup battery voltage drop detection circuit.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention provides a backup battery that uses a lamp to display the voltage drop of a backup battery that becomes a power source in place of the main power supply when the main power supply is abnormal. The voltage drop detection circuit includes: a holding means for holding the voltage drop of the backup battery; a testing means for testing the lighting state of the lamp; and a state for releasing the holding state by the holding means and switching to a testing state for the testing means. It is equipped with a switching means.

(Function) According to the present invention having the above-described configuration, if the backup battery temporarily causes a voltage drop, that is, the voltage becomes lower than a predetermined voltage, it temporarily becomes lower than the alarm voltage for lighting the lamp. Even if the voltage becomes higher than the alarm voltage again, the information indicating the voltage drop caused by the backup battery is held by the holding means and the lamp continues to be lit. Further, the holding state by the holding means is released by the switching means, and the lighting state of the lamp is inspected.

Therefore, the present invention can solve the above problems and provide a highly reliable backup battery voltage drop detection circuit.

(Example) Hereinafter, an example of the present invention will be described based on the drawings.

FIG. 1 is a circuit diagram showing an embodiment of the present invention. In this figure, the same reference numerals as in FIG. 2 indicate the same elements. Further, 11 to 15 are open collector type gates, and 16 is a toggle switch.

First, the procedure for setting the alarm voltage and checking the light emitting diode is as follows. First of all,
The toggle switch 16 is set to the d side, and the variable resistor 6 is set to the a
Move it in the direction of. Then, without removing the backup battery 2 and supplying +5V to the power input terminal 8, a reference voltage is applied to the reference voltage input terminal 9 such that the voltage at the voltage output terminal 10 of the backup battery 2 becomes the alarm voltage value. do. In this state, when +5V is applied to the power supply control circuit 1, the voltage at point α is higher than the threshold transition voltage of the voltage detection IC 3, so the output of the light emitting diode driver 5 becomes high impedance, and the light emitting diode 4 The lights remain off. At this time, when the toggle switch 16 is set to the c side, the output of the gate 15 becomes low level and the light emitting diode 4 lights up, regardless of the voltage at the point α. This allows the light emitting diode to be checked.

Next, when the toggle switch 16 is returned to the d side, the light emitting diode 4 is turned off. In this state, when the variable resistor 6 is moved in the direction b, when the voltage at point α becomes below the threshold transition voltage of the voltage detection IC 3, the output of the voltage detection IC 3 becomes low level and the light emitting diode lights up. , the output of gate 12 becomes low level. After reaching this state,
Even if the variable resistor 6 is moved toward a, the output of the gate 12 is at a low level, so the voltage at point α remains the same as that of the variable resistor 6.
The light emitting diode 4 remains lit. This is the latch operation of this circuit.

When adjusting the alarm voltage, if the variable resistor 6 is moved too far in the direction b, the toggle switch 16
When set to the c side, the output of the gate 12 becomes high impedance, so as the variable resistor 6 is returned to the direction a, the voltage at point α becomes higher than the threshold transition voltage of the voltage detection IC 3. It gets expensive. At this point, toggle switch 1
When the light emitting diode 4 is set to the d side, the light emitting diode 4 is turned off.
In this way, the toggle switch 16 not only checks the light emitting diode 4 but also functions as an alarm voltage release switch when adjusting the alarm voltage, so the alarm voltage can be adjusted as many times as you like while the +5V power is turned on. becomes possible. After the adjustment is completed, the reference voltage at the reference voltage input terminal 9 is removed, and the backup battery 2 is installed.

Next, when +5V is supplied to the power input terminal 8 with the backup battery 2 installed,
If the output voltage of the backup battery 2 is higher than the alarm voltage, the light emitting diode 4 is turned off because the voltage at point α is higher than the threshold transition voltage of the voltage detection IC 3.

Then, when the output voltage of the backup battery 2 becomes less than the alarm voltage while the +5V power is turned on, the voltage at point α becomes less than the threshold transition voltage of the voltage detection IC 3, and the light emitting diode 4 lights up. . At this point, the output of the gate 12 becomes a low level, so the backup battery 2
Even if the output voltage becomes equal to or higher than the alarm voltage again, the light emitting diode 4 will not go out.

In addition, when the backup battery 2 is installed and +5V power is supplied, it is possible to check the lighting of the light emitting diode 4 by setting the switch to the d side.

(Effects of the Invention) As explained above, according to the present invention, the output voltage temporarily drops below the alarm voltage due to an abnormality in the storage device or backup battery that supplies power through this circuit. Even in such a case, it is possible to continue detecting the alarm voltage and easily check the light emitting diode for displaying the alarm, thereby providing a highly reliable backup battery voltage drop detection circuit.

[Brief explanation of drawings]

Figure 1 is a circuit diagram showing one embodiment of the present invention, Figure 2 is a circuit diagram showing an embodiment of the present invention.
The figure is a circuit diagram showing a conventional backup battery voltage drop detection circuit. DESCRIPTION OF SYMBOLS 1... Power supply control circuit, 2... Backup battery, 3... Voltage detection IC, 4... Light emitting diode, 5... Driver for driving light emitting diode, 6...
...Variable resistor, 7...Diode, 8...Power input terminal, 9...Reference voltage input terminal, 10...Voltage output terminal, 11-15...Gate, 16...Toggle switch.

Claims (1)

[Scope of Claims] 1. In a backup battery voltage drop detection circuit that displays a voltage drop of a backup battery that serves as a power source in place of the main power supply when the main power supply is abnormal, the voltage drop of the backup battery is indicated by a lamp. a holding means for holding the lamp; a testing means for testing the lighting state of the lamp; and a switching means for releasing the holding state by the holding means and switching to the testing state by the testing means; occurs, information indicating the voltage drop is held by the holding means to continue lighting the lamp, and the holding state by the holding means is released by the switching means, and the lighting state of the lamp is determined by the testing means. What is claimed is: 1. A voltage drop detection circuit for a backup battery, characterized in that it performs an inspection of