JP2002095178A - Inspection device for backup voltage - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a backup voltage inspection device having a circuit configuration whose power demand is lower, and whose required number of parts is smaller. SOLUTION: This inspection device is composed by providing a diode D3 connected in series with its cathode connected to the cathode (the output of a second power source 103) of a diode D3, a resistor R1 connected in parallel to the diode D3, a capacitor C1 connected between the anode of the diode D3 and the ground potential GND, and the NOT gate IV1 of a Schmitt circuit as a detecting means for detecting the terminal-to-terminal voltage of the capacitor C1. Whether or not a backup power source (a second power source 103) malfunctions, is reported to a control unit (CPU) 105 by an alarm signal BKUP-AL.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backup voltage testing apparatus, and more particularly to a backup voltage testing apparatus having a circuit configuration with lower power consumption and a smaller number of components.

[0002]

2. Description of the Related Art Conventionally, in an electronic device having a memory, a backup battery is provided in the electronic device in order to prevent the power supply from being accidentally shut down due to a power failure or the like and memory data is lost. Is used to automatically flow through the power supply line, or a battery is connected to the power supply line of the electronic device by detecting the interruption of the power supply. By providing such a battery backup configuration, even when the power is cut off, the power of the battery is immediately supplied to the power supply line, so that the voltage of the power supply terminal of the memory is maintained constant without lowering and the data is stored. Can be prevented from disappearing. For example, in an electronic device such as an absolute encoder, a component such as a memory or a CPU that requires data retention even during a power failure is backed up by a battery, but unlike an ordinary OA device,
A backup battery is not mounted inside the electronic device, and backup power is supplied from outside the encoder. In such a configuration, it is checked whether the backup power supply was normal during backup. A mechanism is needed.

[0003] As such a backup voltage inspection apparatus, for example, there is one as shown in FIG. FIG. 4 is a circuit configuration diagram of a backup voltage inspection device incorporated in an electronic device. Referring to FIG. 4, a backup voltage testing apparatus according to the related art includes a voltage level detector 401 for detecting a voltage drop, NOT gates IV11 and IV12, and N
The configuration includes AND gates NA11 and NA12. Here, the NOT gate IV11 uses a CMOS Schmitt circuit in order to make the input impedance large, and the NAND gates NA11, NA11
Reference numeral 12 denotes a latch, and # ALM-CL (# indicates a negative logic signal) is a reset signal. The backup voltage inspection apparatus operates with the backup power supply VB. When the backup power supply voltage VB falls below a predetermined value, the output of the voltage level detector 401 becomes “L” level and the latch (NA11, NA12) ) Is set. After the operating voltage of the electronic device has risen again, the alarm signal BKUP-AL, which is the output of the latch (NA11, NA12), is taken in, so that the backup power supply VB is normal (the power supply voltage VB falls below a predetermined value). Is not detected).

[0004]

By the way, as described above, the backup voltage inspection apparatus is provided with a backup power supply V.
B, and is required only for the voltage test of the backup power supply VB. Therefore, from the viewpoint of reducing the power consumption of the circuit and miniaturization of the device, the components have lower power consumption and more components. A circuit configuration with a small number of points has been desired.
The present invention has been made in view of the above-mentioned conventional circumstances, and has as its object to provide a backup voltage testing apparatus having a circuit configuration with lower power consumption and a smaller number of components.

[0005]

According to a first aspect of the present invention, there is provided a backup voltage testing apparatus including a first power supply and a second power supply for backing up the first power supply.
A back-up voltage testing device comprising a power supply, a cathode connected to the output of the second power supply, a diode connected in series with the second power supply, a resistor connected in parallel with the diode, and an anode of the diode. It comprises a capacitor connected between ground potentials and a detecting means for detecting or measuring a voltage between terminals of the capacitor. In a backup voltage testing apparatus according to a second aspect of the present invention, in the backup voltage testing apparatus according to the first aspect, the detecting means includes a gate circuit having a large input impedance, a voltage detection circuit, or an A / D converter. It is provided.

In the backup voltage inspection apparatus according to the present invention, the voltage of the second power supply for backup is stored and held in a capacitor, and after the first power supply, which is a normal operating voltage, rises, the stored content of the capacitor is restored. By taking in, it is checked whether or not there is any abnormality such as a temporary drop in the voltage of the backup second power supply. More specifically, a circuit configuration in which a diode and a high-resistance parallel circuit are inserted in series between the output of the second power supply and the capacitor makes the charge time of the capacitor relatively long, and the charge discharge time Is relatively short so that the state when the voltage of the second power supply for backup temporarily drops can be stored and held for a certain period of time. Therefore, after the first power supply, which is the normal operating voltage, rises, the detection means detects or measures the voltage between the terminals of the capacitor, thereby determining whether the second power supply for backup is normal. .
The detection of the voltage between the terminals of the capacitor by the detecting means is performed by connecting a gate circuit having a large input impedance to the capacitor and taking in the output of the gate circuit by a control unit or the like. The voltage between the terminals of the capacitor can be measured by the detection means by connecting a voltage detection circuit or an A / D converter having a large input impedance to the capacitor, so that the voltage can be measured as an analog amount or a digital amount, respectively. As described above, the backup voltage inspection apparatus of the present invention can detect the abnormality of the backup power supply with a smaller number of components of the resistor, the diode, the capacitor, and the gate circuit, the voltage detection circuit, or the A / D converter. This can contribute to downsizing of an electronic device in which the backup voltage inspection device is incorporated. Further, power consumption can be reduced, and as a result, the life of the backup power supply can be further extended.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of a backup voltage inspection apparatus according to the present invention will be described.
The second embodiment will be described in detail with reference to the drawings. [First Embodiment] FIG. 1 is a partial configuration diagram of an electronic apparatus in which a backup voltage testing apparatus according to a first embodiment of the present invention is incorporated. This electronic device has a normal operating voltage V
A first power supply 101 for supplying CC and a normal operating voltage VC
This is a battery backup system including a backup second power supply 103 for retaining data in the volatile memory 107 and the like when C does not exist. Here, the second power supply 103 is realized by a battery, for example, and outputs the voltage VB. The first power supply 101 is connected via a diode D1 to:
The second power supply 103 is connected to a backup power supply voltage line (VCB) via a diode D2 to back up the memory 107 and the like. Further, components such as the control unit (CPU) 105 that do not require backup receive a normal operating voltage from the first power supply 101. In FIG. 1, a backup voltage testing apparatus 110 of the present embodiment has a cathode connected to a diode D2.
A diode D3 connected in series to the cathode (output of the second power supply 103), a resistor R1 connected in parallel with the diode D3, a capacitor C1 connected between the anode of the diode D3 and the ground potential GND, This is a configuration including a NOT gate IV1 of a Schmitt circuit as a detecting means for detecting a voltage between terminals of the capacitor C1, and controls presence / absence of abnormality of a backup power supply (second power supply 103) via an alarm signal BKUP-AL. (CP
U) Notify 105. That is, the backup voltage inspection apparatus 110 of the present embodiment stores and holds the voltage VB of the second power supply 103 for backup in the capacitor C1, and after the first power supply 101, which is a normal operating voltage, rises, The storage contents of C1 are stored in the control unit (CP
U) 105 is to check whether there is any abnormality such as a temporary drop in the voltage VB of the second power source 103 for backup.

Next, the operation of the backup voltage inspection apparatus 110 according to the present embodiment will be described with reference to FIG. FIG.
FIG. 4 is an explanatory diagram illustrating a temporal change of a potential VCB of a backup power supply voltage supply line and a voltage VC1 between terminals of a capacitor C1. In FIG. 2, first, the memory 107 and the like are backed up by the second power supply 103 as an initial state, and the potential VC of the backup power supply voltage supply line is
B is the voltage VB of the second power supply 103. At this time, the capacitor C1 is connected to the voltage VB of the second power source 103 via the resistor R1.
And the voltage VC1 between the terminals of the capacitor C1.
Is substantially equal to the potential VCB of the backup power supply voltage supply line. Since a high resistance is used for the resistor R1, the time required for charging the capacitor C1 is relatively long. Then, at timing TA, the second
When an abnormality occurs in the power supply 103 and the potential VCB of the backup power supply voltage supply line sharply decreases, the capacitor C1
Is discharged by a relatively low-resistance discharge circuit via the diode D3, the voltage VC1 between the terminals of the capacitor C1 drops following the potential VCB of the backup power supply voltage supply line. After that, even if the abnormal state of the second power supply 103 is resolved and the potential VCB of the backup power supply voltage supply line returns to the voltage VB of the second power supply 103, the capacitor C1
, The voltage VC1 between the terminals of the capacitor C1 does not easily rise. Then, at timing T
In B, the potential VCB of the backup power supply voltage supply line is switched to the normal operating voltage VCC.
When 1 starts up, the control unit (CPU) 105
The voltage VC1 between the terminals of the capacitor C1 is supplied to the NOT gate IV.
The alarm signal BKUP-AL logically inverted in step 1 is fetched. In the example of FIG. 2, the alarm signal BKUP-AL becomes “H” level, and the second power supply 103 for backup is used.
Can be confirmed that there was an abnormality. The reason why the alarm signal BKUP-AL is generated via the NOT gate IV1 of the Schmitt circuit having a large input impedance is to allow the discharge current of the capacitor C1 to flow mainly through the diode D3. As described above, the backup voltage inspection device 11 of the present embodiment
0, it is possible to detect the abnormality of the second power supply 103 for backup with a smaller number of components of the resistor R1, the diode D3, the capacitor C1, and the NOT gate IV1 of the Schmitt circuit.
0 can be contributed to the miniaturization of the device of the electronic equipment. Further, since the power consumption of the backup voltage testing device 110 that consumes the power of the second power supply 103 can be reduced, the life of the second power supply (battery) 103 can be further extended. In addition, in the conventional backup voltage inspection apparatus shown in FIG. 4, after confirming whether or not the backup power supply is abnormal, it is necessary to reset (cancel) the storage contents of the latches (NA11, NA12) by the reset signal # ALM-CL. On the other hand, in the backup voltage inspection apparatus 110 of the present embodiment, the capacitor C1
Is charged to the operating voltage VCC after a long charging time, and the stored content indicating that an abnormality has occurred in the second power supply 103 is reset, so that there is no need to perform a reset operation again.

[Second Embodiment] FIG. 3 is a partial configuration diagram of an electronic apparatus in which a backup voltage testing apparatus according to a second embodiment of the present invention is incorporated. Since the electronic device is the same as that of the first embodiment, the description is omitted.
In FIG. 3, the backup voltage inspection device 210 of the present embodiment includes a diode D3, a resistor R1 connected in parallel with the diode D3, a capacitor C1 connected between the anode of the diode D3 and the ground potential GND, and a capacitor C1. The configuration is such that an A / D converter 211 having a large input impedance is provided as detection means for measuring a voltage between terminals. That is, the backup voltage inspection device 210 of the present embodiment includes the A / D converter 211 instead of the NOT gate IV1 of the first embodiment, and converts the voltage VB of the second power source 103 for backup to the capacitor C1.
In the first power supply 1 which is a normal operating voltage.
After the voltage 01 has risen, the voltage between the terminals of the capacitor C1 is taken into the control unit (CPU) 205 as the digital amount detection voltage BKUP-D, so that the voltage VB of the second power source 103 for backup temporarily decreases. It is to check whether there is any abnormality such as. As described above, in the backup voltage inspection apparatus 210 of the present embodiment, the abnormality of the second power supply 103 for backup is detected with a smaller number of components of the resistor R1, the diode D3, the capacitor C1, and the A / D converter 211. Accordingly, it is possible to contribute to downsizing of an electronic device in which the backup voltage inspection device 210 is incorporated. Further, since the power consumption of the backup voltage testing device 210 that consumes the power of the second power supply 103 can be reduced, the life of the second power supply (battery) 103 can be further extended.

In the first and second embodiments described above, the alarm signal BKUP-AL output from the NOT gate IV1 and the detection voltage BKUP-D output from the A / D converter 211 are controlled. Unit (CPU)
Although it has been determined that the backup power supply 103 has received an error and that the backup second power supply 103 has an abnormality, the present invention is not limited to such a configuration. For example, the detection signal (alarm signal BKUP-AL) may be used. And the detection voltage BKUP-D) may be output to an alarm or a display to notify the user directly. Also, a configuration using a voltage detection circuit with a large input impedance instead of the NOT gate IV1 in the first embodiment or the A / D converter 211 in the second embodiment, or a voltage detection circuit with a large input impedance, A configuration is also conceivable in which A / D converters are connected in series to convert a detection result into a digital value and take in the control unit (CPU). Here, various modes can be considered for the voltage detection circuit. For example, a comparator that compares with a predetermined reference voltage may be used, or the A / D converter 211 itself may be regarded as a voltage detection circuit. Further, when accuracy is required, a modulation DC voltmeter, an integral digital voltmeter, or the like may be used.

[0011]

As described above, according to the backup voltage testing apparatus of the present invention, the voltage of the second power source for backup is stored and held by the capacitor, and the first power source, which is the normal operating voltage, is turned on. After that, by taking in the stored contents of the capacitor, it is checked whether there is any abnormality such as a temporary drop in the voltage of the backup second power supply. By connecting a gate circuit having a large input impedance to the capacitor and taking in the output of the gate circuit by a control unit or the like, the measurement of the voltage between the terminals of the capacitor by the detecting means is performed by measuring the voltage having a large input impedance to the capacitor. Since the measurement was made by connecting a detection circuit or A / D converter, resistance, diode, capacitor, In addition, it is possible to detect the abnormality of the backup power supply with a smaller number of components of the gate circuit, the voltage detection circuit or the A / D converter, thereby contributing to the miniaturization of the electronic equipment in which the backup voltage inspection device is incorporated. it can. In addition, since power consumption can be reduced, the life of the backup power supply can be further extended.

[Brief description of the drawings]

FIG. 1 is a partial configuration diagram of an electronic device in which a backup voltage testing device according to a first embodiment of the present invention is incorporated.

FIG. 2 is an explanatory diagram exemplifying a temporal change of a potential of a backup power supply voltage supply line and a voltage between terminals of a capacitor;

FIG. 3 is a partial configuration diagram of an electronic device in which a backup voltage testing device according to a second embodiment of the present invention is incorporated.

FIG. 4 is a circuit configuration diagram of a backup voltage testing device incorporated in a conventional electronic device.

[Explanation of symbols]

 101 first power supply 103 second power supply 105, 205 control unit (CPU) 107 memory 110, 210 backup voltage inspection device D1-D3 diode R1 resistor C1 capacitor VCC output of first power supply 101 VB output of second power supply 103 VCB backup power supply Potential of voltage supply line IV1 NOT gate (detection means) BKUP-AL Alarm signal 211 A / D converter (detection means) BKUP-D detection voltage

Claims (2)

[Claims] 1. A backup voltage tester comprising: a first power supply; and a second power supply for backing up the first power supply, wherein a cathode is connected to an output of the second power supply, and is connected in series with the second power supply. And a resistor connected in parallel with the diode, a capacitor connected between the anode of the diode and a ground potential, and a detecting unit for detecting or measuring a voltage between terminals of the capacitor. Backup voltage inspection device. 2. The backup voltage inspection apparatus according to claim 1, wherein the detection unit includes one of a gate circuit having a large input impedance, a voltage detection circuit, and an A / D converter.