JP2013114456A - Voltage monitoring device and voltage monitoring method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a voltage monitoring device and the like for accurately and reliably detecting a fault of a power supply device in an electronic apparatus.SOLUTION: A voltage monitoring device comprises: threshold operation means that calculates a threshold on the basis of a control signal output from an operation processing device which operates with output voltage of a DC/DC converter; and comparison means that determines whether a first voltage value acquired by measuring the output voltage is within a range of the threshold.

Description

  The present invention relates to a technical field for monitoring a power source of an electronic device or the like.

  In recent years, electronic devices such as servers and personal computers are required not only to operate stably but also to operate with less power.

  In particular, the server is required to operate 24 hours a day, 365 days a year without rest. Therefore, the power consumed by the server increases in proportion to the operating time. In addition, with the improvement of the processing capacity of the server, the power consumed is further increased.

  Against this background, there is a demand for reducing the power consumed by the server, and there are a wide variety of techniques for reducing the power consumed by the server.

  For example, it is known that an arithmetic processing unit consumes the most power among the components constituting the server. For this reason, the arithmetic processing device has a technique for dynamically changing the power according to the load state, thereby reducing the power consumption.

  More specifically, when performing processing such as a program, the arithmetic processing device requests power necessary for processing from the power supply device according to the load status. The power supply device supplies power to the arithmetic processing device in response to the request. Therefore, a device for monitoring the voltage is connected to the power supply device in order to supply stable power. For example, Patent Document 1 discloses a power supply monitoring device that monitors a power supply abnormality.

  Hereinafter, the power supply monitoring device 50 described in Patent Document 1 will be described with reference to FIG.

  In the power supply monitoring device 50, a CPU (Central Processing Unit) 57 outputs information indicating a threshold set in advance according to a user operation or the like to the monitoring control unit 51. The output threshold value is stored in the threshold value storage unit 53.

  Further, the CPU 57 outputs a control signal to the monitoring control unit 51 in order to instruct to start monitoring the power supply according to the user's operation. The monitoring control unit 51 starts monitoring the power supply according to the output control signal.

  The voltage value storage device 55 converts the voltage value output from the power source 56 from an analog voltage signal to a digital signal, and outputs the digital value to the voltage value acquisition unit 52. The voltage value acquisition unit 52 stores the voltage value output from the voltage value storage device 55.

  The comparison unit 54 compares the threshold value stored in the threshold value storage unit 53 with the voltage value stored in the voltage value acquisition unit 52. The comparison unit 54 has a function of detecting a power supply abnormality when the voltage value is less than a threshold value (or a predetermined value or more). Thereby, the power supply monitoring apparatus 50 detects an abnormality based on the result of determining whether or not the voltage value of the power supply falls below a predetermined threshold value.

  As described above, Patent Document 1 discloses a technique for detecting an abnormality by comparing a voltage output from a power supply device with a preset threshold value.

JP 2010-146278 A

  However, although Patent Document 1 sets a threshold value in advance, it does not specifically disclose how to set the threshold value, so the threshold value cannot be easily set.

  Further, the power supply monitoring device 50 detects a power supply abnormality when the voltage drops and becomes less than the threshold value. For this reason, monitoring that the measured voltage value falls below the threshold is not considered to monitor the voltage that is dynamically output according to the load status of the arithmetic processing unit described above. Unable to detect abnormalities reliably.

  For example, when an overvoltage is output to the CPU 57, the power supply monitoring device 50 cannot detect the abnormal voltage because the voltage value does not fall below the threshold value.

  Furthermore, in Patent Document 1, for an instruction to start power supply monitoring, the CPU issues an instruction to start power supply monitoring in accordance with an instruction from the host device or a user operation. For this reason, if power monitoring is started in response to an instruction from the host device or a user operation, the voltage value cannot be monitored every time it is dynamically output. It cannot be monitored.

  A main object of the present invention is to provide a voltage monitoring device or the like that accurately and reliably detects a failure of a power supply device, which is the problem described above.

  In order to achieve the above object, a voltage monitoring apparatus according to the present invention has the following configuration.

That is, the voltage monitoring device according to the present invention is
Threshold calculation means for calculating a threshold based on a control signal output from an arithmetic processing device that operates according to the output voltage of the DC / DC converter;
Comparison means for determining whether or not a first voltage value obtained by measuring the output voltage is within the threshold range;
It is characterized by providing.

  According to the present invention, it is possible to accurately and reliably detect a failure of a power supply device.

It is a block diagram which shows the structure of the voltage monitoring apparatus in the 1st Embodiment of this invention. It is a block diagram which shows the structure of the voltage monitoring apparatus in the 2nd Embodiment of this invention. It is a block diagram which shows the structure of the voltage monitoring apparatus in the 3rd Embodiment of this invention. It is a flowchart figure which shows the process which the voltage monitoring apparatus in the 3rd Embodiment of this invention performs. It is a flowchart figure which shows the threshold value calculation process which the voltage monitoring apparatus in the 3rd Embodiment of this invention performs. It is a flowchart figure which shows the voltage value calculation process which the voltage monitoring apparatus in the 3rd Embodiment of this invention performs. It is a block diagram which shows the structure of the voltage monitoring apparatus in the Example of 3rd Embodiment which concerns on this invention. It is a block diagram which shows the structure of the memory | storage device in the Example of 3rd Embodiment based on this invention. It is a block diagram about the structure of the voltage sensor unit in the Example of 3rd Embodiment which concerns on this invention. It is a block diagram which shows the structure of the power supply monitoring apparatus in patent document 1. FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

<First Embodiment>
FIG. 1 is a block diagram showing a configuration of a voltage monitoring apparatus 1 according to the first embodiment of the present invention.

  In FIG. 1, the voltage monitoring device 1 includes a threshold value calculation unit 4 and a comparator 5.

  More specifically, the arithmetic processing unit 2 outputs a voltage value necessary for processing such as a program to a DC / DC (Direct Current / Direct Current) converter 3 and a threshold value calculation unit 4 as a control signal.

  The DC / DC converter 3 outputs a first voltage value desired by the arithmetic processing device 2 to the arithmetic processing device 2 and the voltage measuring unit 6 based on the control signal output by the arithmetic processing device 2.

  In the following description, the voltage value measured by the voltage measuring unit 6 is referred to as a first voltage value (the same applies to the following embodiments). The voltage measuring unit 6 measures the first voltage value output by the DC / DC converter 3. The voltage measuring unit 6 outputs the measured first voltage value to the comparator 5. Here, for convenience of explanation, there is no difference between the output voltage of the DC / DC converter 3 and the measurement value output by the voltage measurement unit 6, and both represent the first voltage value.

    In the following description, for convenience of description, the voltage value calculated by the threshold calculation unit 4 is referred to as a second voltage value (the same applies to the following embodiments). The threshold calculation unit 4 calculates a second voltage value desired by the arithmetic processing device 2 based on the control signal. Next, the threshold value calculation unit 4 calculates an upper limit threshold value and a lower limit threshold value as an allowable range based on the second voltage value. The threshold value calculation unit 4 outputs the calculated threshold value to the comparator 5.

  The comparator 5 determines whether or not the first voltage value is within an allowable range of threshold values (upper threshold value and lower threshold value).

  When the comparator 5 determines that the first voltage value exceeds the allowable range of the threshold, the comparator 5 notifies the threshold calculator 4 that the first voltage value has exceeded the allowable range of the threshold. On the other hand, when the comparator 5 determines that the first voltage value is within the threshold tolerance, the comparator 5 notifies the threshold calculator 4 that the first voltage value is within the threshold tolerance.

  The threshold value calculation unit 4 determines that the first voltage value output by the DC / DC converter 3 is abnormal when the comparator 5 is notified that the first voltage value exceeds the allowable range of the threshold value. On the other hand, the threshold value calculation unit 4 determines that the first voltage value output by the DC / DC converter 3 is normal when the comparator 5 is notified that the first voltage value is within the allowable range of the threshold value. To do. If the threshold value calculation unit 4 determines that there is an abnormality, it executes an abnormality process.

  Since this abnormality process can employ a general method such as a process of disconnecting the DC / DC converter 3 determined to be abnormal from the server, detailed description in the embodiment is omitted.

  What is necessary is just to comprise the process which monitors the said voltage so that it may be automatically started by the threshold value calculating part 4 acquiring the control signal output by the arithmetic processing apparatus 2 for every predetermined time period. In addition, what is necessary is just to determine arbitrarily about a predetermined time period according to a user's use environment.

  As described above, according to the voltage monitoring apparatus 1 according to the present embodiment, by acquiring the control signal output by the arithmetic processing apparatus 2, the voltage is obtained every time the control signal is output without an instruction from the user. Since monitoring is performed, it is possible to reliably detect an abnormality. Further, according to the present embodiment, by comparing the threshold value calculated based on the control signal output from the arithmetic processing unit 2 with the voltage value output by the DC / DC converter, the voltage value can be more accurately calculated. Abnormalities can be detected.

<Second Embodiment>
Next, a second embodiment based on the voltage monitoring apparatus 1 according to the first embodiment described above will be described. In the following description, the characteristic part according to the present embodiment will be mainly described. At this time, the same reference numerals are assigned to the same configurations as those in the first embodiment described above, and the duplicate description is omitted.

  FIG. 2 is a block diagram showing the configuration of the voltage monitoring device 1a according to the second embodiment of the present invention.

  In the present embodiment, a case where the storage unit 7 and the threshold value calculation unit 8 are applied to the voltage monitoring apparatus 1 described in the first embodiment will be described.

  More specifically, the arithmetic processing unit 2 outputs a voltage value necessary for processing such as a program to the DC / DC converter 3 and the storage unit 7 as a control signal.

  In the following description, in this embodiment, for convenience of explanation, a control signal already stored in the storage unit 7 is referred to as a first control signal, and a new control signal is referred to as a second control signal (the following embodiments). The same applies to the above). When the arithmetic processing unit 2 outputs a new control signal (second control signal), the storage unit 7 reads the control signal (first control signal) that has already been stored. Next, the storage unit 7 compares the read first control signal with the second control signal (that is, the storage unit 7 receives a new control signal (second control signal) by the arithmetic processing unit 2). In response to the output, the control signal (first control signal) that has already been stored is read out, and then the storage unit 7 compares the read first control signal with the second control signal. Translation).

  The storage unit 7 stores the second control signal when it is determined as a result of the comparison that the control signal has fluctuated (the first control signal and the second control signal are different). Furthermore, the storage unit 7 notifies the threshold value calculation unit 8 that the control signal has changed.

  When the server is initialized, the second control signal is stored without comparing the control signals. In this case, the storage unit 7 notifies the threshold value calculation unit 8 that the control signal has changed.

  The threshold value calculation unit 8 reads the control signal stored in the storage unit 7 when the notification is acquired.

  The threshold value calculation unit 8 calculates a second voltage value desired by the calculation processing device 2 based on the read control signal (details will be described later in the embodiment). Next, an upper limit threshold and a lower limit threshold are calculated as allowable ranges based on the second voltage value. As an example, the threshold value calculation unit 8 may set + 5% of the second voltage value as the upper threshold value and set −5% of the second voltage value as the lower threshold value. In addition, although the setting method was shown as an example, not only this setting method but a user should just set arbitrarily. The threshold value calculation unit 8 outputs the calculated threshold value to the comparator 5.

As described above, according to the voltage monitoring device 1a according to the present embodiment, the effects described in the first embodiment can be enjoyed, and the control signals output by the arithmetic processing device are compared, and the control signal is obtained. Since the monitoring is triggered by the change, the monitoring can be performed more efficiently.
<Third Embodiment>
Next, a third embodiment based on the voltage monitoring device 1 and the voltage monitoring device 1a according to each embodiment described above will be described with reference to FIGS. In the following description, the characteristic part according to the present embodiment will be mainly described. At this time, the same reference numerals are assigned to the same configurations as those in the above-described embodiments, and duplicate descriptions are omitted.

  This embodiment demonstrates the case where the threshold value storage part 9 and the voltage value storage part 10 are applied to the voltage monitoring apparatus 1 and the voltage monitoring apparatus 1a demonstrated in each embodiment.

  FIG. 3 is a block diagram showing the configuration of the voltage monitoring device 1b according to the third embodiment of the present invention.

  More specifically, the threshold storage unit 9 stores the upper limit threshold and the lower limit threshold output by the threshold calculation unit 8.

  The voltage value storage unit 10 stores the first voltage value measured by the voltage measurement unit 6.

  FIG. 4 is a flowchart illustrating processing performed by the voltage monitoring device 1b according to the third embodiment. The processing procedure of the voltage monitoring device 1b will be described along the flowchart.

  The voltage monitoring device 1b performs the respective processes in parallel by the storage unit 7 and the DC / DC converter 3 acquiring the control signal output from the arithmetic processing device 2.

  The arithmetic processing device 2 outputs a new control signal (second control signal) to the storage unit 7 (step S1).

  When the arithmetic processing unit 2 outputs a new control signal (second control signal), the storage unit 7 reads the control signal (first control signal) that has already been stored. Next, the storage unit 7 compares the read first control signal with the second control signal (step S2).

  When it is determined that the control signal has changed (“YES” in step S2), the storage unit 7 stores the second control signal. Furthermore, the storage unit 7 notifies the threshold value calculation unit 8 that the control signal has changed. On the other hand, when determining that the control signals are the same, the storage unit 7 waits for voltage monitoring (“NO” in step S2).

  When the server is initialized, the second control signal is stored without comparing the control signals. In this case, the storage unit 7 notifies the threshold value calculation unit 8 that the control signal has changed.

  When it is determined that the control signal has changed (“YES” in step S2), a threshold value calculation process (step S3) and a voltage value calculation process (step S4) described below are executed.

  FIG. 5 is a flowchart showing the threshold value calculation process of the present embodiment. The detailed procedure of the threshold value calculation process in step 3 will be described along the flowchart.

  When the threshold calculation unit 8 acquires the notification output by the storage unit 7, the threshold calculation unit 8 reads the control signal stored in the storage unit 7. The threshold calculation unit 8 calculates a second voltage value desired by the calculation processing device 2 based on the read control signal. Next, the threshold value calculation unit 8 calculates an upper limit threshold value and a lower limit threshold value as an allowable range based on the second voltage value. The threshold value calculation unit 8 outputs the calculated threshold value to the threshold value storage unit 9 (step S31).

  The threshold storage unit 9 stores the threshold output by the threshold calculation unit 8 (step S32).

  FIG. 6 is a flowchart showing the voltage value calculation processing of the present embodiment. The detailed procedure of the voltage value calculation process in step S4 will be described along this flowchart.

  The DC / DC converter 3 outputs a voltage desired by the arithmetic processing device 2 to the arithmetic processing device 2 and the voltage measuring unit 6 based on the acquired control signal (step S41). Here, since the operation output by the DC / DC converter 3 is general, a detailed description thereof will be omitted.

  The voltage measuring unit 6 measures the first voltage value output by the DC / DC converter 3. Next, the measured first voltage value is output to the voltage value storage unit 10 (step S42).

  The voltage value storage unit 10 stores the first voltage value output from the voltage measurement unit 6 (step S43).

  The comparator 5 reads the stored threshold value by performing the threshold value calculation process. Next, the comparator 5 reads the first voltage value stored by performing the voltage value calculation process. Further, the comparator 5 determines whether or not the first voltage value is within a threshold allowable range (step S5).

  When the comparator 5 determines that the first voltage value exceeds the allowable range of the threshold values (the upper threshold value and the lower threshold value) ("NO" in step S6), the comparator 5 determines that the first voltage value is the threshold value. The fact that the allowable range has been exceeded is notified (step S8). On the other hand, when the comparator 5 determines that the first voltage value is within the allowable range of the threshold (“YES” in step S6), the comparator 5 determines that the first voltage value is within the allowable range of the threshold. It is notified (step S7).

  The threshold value calculation unit 8 determines that the first voltage value output by the DC / DC converter 3 is abnormal when the comparator 5 is notified that the first voltage value exceeds the allowable range of the threshold value ( “NO” in step S9). On the other hand, the threshold value calculation unit 8 determines that the first voltage value output by the DC / DC converter 3 is normal when the comparator 5 is notified that the first voltage value is within the allowable range of the threshold value. ("YES" in step S9). When the comparator 5 is notified of the occurrence of an abnormality, the threshold value calculation unit 8 executes a predetermined abnormality process (not shown) (step S10).

As described above, according to the voltage monitoring device 1b according to the present embodiment, the effects described in the first to second embodiments can be enjoyed, and the threshold value and the voltage value storage unit can be further provided. Since the voltage value can be held, the threshold value and the voltage value can be efficiently compared.
<Example>
Next, as a more specific example according to the above-described third embodiment, a voltage monitoring device 1c will be described with reference to FIGS. In the following description, the characteristic part according to the present embodiment will be mainly described. At this time, the same reference numerals are assigned to the same configurations as those in the above-described embodiments, and duplicate descriptions are omitted.

  FIG. 7 is a block diagram showing the configuration of the voltage monitoring device 1c according to the embodiment of the present invention.

  In FIG. 7, the voltage monitoring device 1 c includes a storage device 31, a system management controller 32, and a voltage sensor unit 33.

  The storage device 31 will be described with reference to FIG.

  In FIG. 8, the storage device 31 includes a storage unit 34. The storage unit 31 corresponds to the storage unit 7 in the third embodiment. As an example, the storage device 31 may be a general-purpose register, an I2C (Inter Integrated Circuit) register (registered trademark), or a nonvolatile semiconductor memory, but is not limited to these storage media.

  The system management controller 32 corresponds to the threshold value calculation unit 8 in the third embodiment. For example, the system management controller 32 may be a BMC (Baseboard Management Controller).

  Next, the voltage sensor unit 33 will be described with reference to FIG.

  In FIG. 9, the voltage sensor unit 33 includes a comparator 5, a voltage measurement unit 6, a threshold storage unit 9, and a voltage value storage unit 10.

  Next, an operation performed by the voltage monitoring device 1c in the present embodiment will be described.

  The arithmetic processing device 2 outputs a VID (Voltage Identification Digital) corresponding to the control signal described in the third embodiment to the DC / DC converter 3 and the storage device 31.

  The arithmetic processing device 2 notifies the storage device 31 of a desired voltage value by outputting VID. In addition, the DC / DC converter 3 is instructed to output the desired voltage.

  In the following description, in this embodiment, the control signal already stored in the storage device 31 is referred to as a first VID, and the newly output control signal is referred to as a second VID. When a new control signal (second VID) is output from the arithmetic processing unit 2, the storage device 31 reads the control signal (first VID) that has already been stored. The storage device 31 compares the read first VID with the second VID. The first VID corresponds to the first control signal described in the third embodiment. The second VID corresponds to the second control signal described in the third embodiment.

  If the storage device 31 determines that the control signal has changed, the storage device 31 stores the second VID in the storage unit 34. Furthermore, the storage device 31 notifies the system management controller 32 that the control signal has changed. On the other hand, if the storage device 31 determines that the control signals are the same, it waits for voltage monitoring.

  When the server is initialized, the second VID is stored without comparing the VID. In this case, the storage device 31 notifies the system management controller 32 that the control signal has changed.

  When acquiring the notification, the system management controller 32 reads the VID stored in the storage unit 34.

  The system management controller 32 calculates a second voltage value desired by the arithmetic processing device 2 based on the VID. Here, as an example, the VID has 1-bit information. The system management controller 32 calculates the second voltage value by decoding the t VIDs output by the arithmetic processing unit 2. More specifically, when two VIDs of VID [1] = 0 and VID [2] = 1 are output from the arithmetic processing unit 2, the voltage value corresponding to VID [1] = 0 is 0. 8V. Next, the voltage value corresponding to VID [2] is set to 0V. In this case, the voltage value required by the arithmetic processing device 2 can be obtained by the following equation. VID [1] (0.8V) + VID [2] (0V) = 0.8V. Therefore, the voltage value required by the arithmetic processing device 2 can be calculated as 0.8V. For convenience of explanation, a simple numerical value has been described as an example, but it is not limited to this because it differs depending on the type of the arithmetic processing device 2 and the like.

  Next, the system management controller 32 calculates the upper limit threshold and the lower limit threshold as an allowable range based on the second voltage value. The system management controller 32 outputs the calculated threshold value to the voltage sensor unit 33.

  The voltage sensor unit 33 stores the threshold value calculated by the system management controller 32 in the threshold value storage unit 9.

  The comparator 5 determines whether or not the first voltage value is within an allowable range between the upper limit threshold and the lower limit threshold. When the comparator 5 determines that the first voltage value exceeds the allowable range of the threshold values (the upper threshold value and the lower threshold value), the comparator 5 notifies the system management controller 32 that the first voltage value has exceeded the allowable range of the threshold value. To output an alarm signal. On the other hand, when the comparator 5 determines that the first voltage value is within the allowable range of the threshold, in order to notify the system management controller 32 that the first voltage value is within the allowable range of the threshold, Outputs an alarm signal. More specifically, the alarm signal output from the comparator 5 outputs the numerical value 0 when notifying normality. On the other hand, the alarm signal outputs a numerical value of 1 when notifying abnormality. As an example, the numerical value of the alarm signal is limited. However, the present invention is not limited to this, and it is only necessary to be able to determine whether the voltage value is abnormal or normal.

  When the system management controller 32 acquires an alarm signal that notifies the comparator 5 that the first voltage value has exceeded the allowable range of the threshold, the system management controller 32 abnormally detects the first voltage value output by the DC / DC converter 3. Judge. On the other hand, when the system management controller 32 acquires an alarm signal that notifies the comparator 5 that the first voltage value is within the allowable range of the threshold value, the first voltage value output by the DC / DC converter 3. Is determined to be normal. If the system management controller 32 determines that there is an abnormality, it executes a predetermined abnormality process (not shown).

  As described above, according to the voltage monitoring apparatus according to the present embodiment, the effects described in the first to third embodiments can be enjoyed, and the voltage monitoring apparatus described in the third embodiment is further integrated with the integrated circuit. It can be realized by using it.

  In the present invention described with the above-described embodiments as an example, for convenience of explanation, the case of having a plurality of arithmetic processing devices is not clearly described. By providing the voltage sensor unit 33, the arithmetic processing unit, and the plurality of storage devices 31, the voltage can be monitored. Furthermore, since the system management controller 32 and the voltage sensor unit 33 are used in common for a plurality of arithmetic processing units, the manufacturing cost can be reduced.

  The present invention is not limited to the embodiments described above. The present invention is applicable to various electronic devices equipped with an arithmetic processing device such as a personal computer, a POS (Point Of Sale) system, a server, a copier, or a multifunction peripheral, and an integrated circuit.

DESCRIPTION OF SYMBOLS 1 Voltage monitoring apparatus 1a Voltage monitoring apparatus 1b Voltage monitoring apparatus 1c Voltage monitoring apparatus 2 Arithmetic processing apparatus 3 DC / DC converter 4 Threshold calculation part 5 Comparator 6 Voltage measurement part 7 Storage part 8 Threshold calculation part 9 Threshold storage part 10 Voltage value Storage unit 31 Storage device 32 System management controller 33 Voltage sensor unit 34 Storage unit 50 Power supply monitoring device 51 Monitoring control unit 52 Voltage value acquisition unit 53 Threshold storage unit 54 Comparison unit 55 Voltage value storage device 56 Power supply 57 CPU

Claims (10)

Threshold calculation means for calculating a threshold based on a control signal output from an arithmetic processing device that operates according to the output voltage of the DC / DC converter;
Comparison means for determining whether or not a first voltage value obtained by measuring the output voltage is within the threshold range;
A voltage monitoring device comprising: In response to a new second control signal being output as the control signal from the arithmetic processing unit, the second control signal is compared with the first control signal that has already been stored. Storage means for storing the second control signal instead of the first control signal when it is determined that the control signals are different from each other;
Notification means for notifying the threshold value calculation means that the second control signal is stored as the control signal;
The voltage monitoring apparatus according to claim 1, further comprising: The threshold value calculation means includes
The second voltage value is calculated based on the control signal, and an upper limit threshold and a lower limit threshold are calculated as the threshold based on the calculated second voltage value. 2. The voltage monitoring apparatus according to 2. The comparison means includes
When the first voltage value is out of the range between the upper threshold and the lower threshold,
4. The voltage monitoring apparatus according to claim 3, wherein the threshold value calculating means is notified that the first voltage value is out of a threshold range. The threshold value calculation means includes
The output voltage of the DC / DC converter is determined to be abnormal when notified from the comparison means that the first voltage is out of a range between the upper threshold and the lower threshold. Item 5. The voltage monitoring device according to Item 4. Threshold storage means for storing the threshold;
Voltage storage means for storing the first voltage value;
The voltage monitoring apparatus according to any one of claims 1 to 5, further comprising: The threshold value calculation means includes
7. The threshold value is recalculated in response to a notification that the first control signal and the second control signal are different from each other by the notification unit. The voltage monitoring apparatus in any one. Calculating a threshold value using an arithmetic means based on a control signal output from an arithmetic processing device that operates according to the output voltage of the DC / DC converter;
A voltage monitoring method comprising: determining whether or not a first voltage value acquired by measuring the output voltage is within the threshold range using a comparator. In response to a new second control signal being output as the control signal from the arithmetic processing unit, the second control signal is compared with the already stored first control signal,
As a result of the comparison, when it is determined that the first control signal is different from the second control signal, the second control signal is stored in the storage means instead of the first control signal,
9. The voltage monitoring method according to claim 8, wherein the calculation means is notified that the second control signal is stored as the control signal. In calculating the threshold,
9. The second voltage value is calculated based on the control signal, and an upper limit threshold value and a lower limit threshold value are calculated as the threshold value based on the calculated second voltage value. 9. The voltage monitoring method according to 9.

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