Detection circuit, detection method, power supply circuit, and data storage system

Abstract

To provide a technique that enables the accurate detection of a capacitor status.SOLUTION: A detection circuit 18 comprises: a current source 180 that sources a constant current to a capacitor or sinks a constant current from the capacitor; a voltage measurement device 182 that measures voltages of the capacitor at three or more timing points when the constant current is sourced to the capacitor by the current source 180 or when the constant current is sunk from the capacitor by the current source 180; a calculation part 192 that approximates measurement results of the voltages of the capacitor at three or more timing points with a primary straight line and calculates an inclination of a primary straight line; and a detection part 194 that detects a state of the capacitor based on the inclination of the primary straight line calculated by the calculation part 192.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a sensing circuit, a sensing method, a power supply circuit, and a data storage system. [Background technology]

[0002] Conventionally, techniques for measuring the capacitance value of a capacitor have been proposed. For example, Patent Document 1 describes a technique in which a charged capacitor is discharged, a timer is used to count the time required for the voltage of the capacitor to change by a predetermined voltage width, and the capacitance value of the capacitor is measured using the counted result. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-195234

[0004] [overview] However, with the technology described in Patent Document 1, if an error occurs in detecting two voltages having a predetermined voltage width, the capacitance value of the capacitor cannot be measured accurately.

[0005] The present disclosure has been made in light of the above circumstances, and one of its exemplary purposes is to provide a technique that enables accurate detection of the state of a capacitor.

[0006] One aspect of the present disclosure is a detection circuit that includes a current source that sources a constant current to a capacitor or sinks a constant current from the capacitor, a voltage measuring device that measures the voltage of the capacitor at three or more timing points when the constant current is being sourced to the capacitor by the current source or sunk from the capacitor by the current source, a calculation unit that approximates the measurement results of the voltage of the capacitor at the three or more timing points to a linear line and calculates the slope of the linear line, and a detection unit that detects the state of the capacitor based on the slope of the linear line calculated by the calculation unit.

[0007] Any combination of the above components and conversion of the expressions of the present disclosure into methods, devices, systems, etc. are also valid aspects of the present disclosure. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a block diagram of a data storage system according to one embodiment of the present disclosure. [Figure 2] FIG. 2 is a diagram for explaining an example of the operation of the backup power supply circuit when a power supply voltage is supplied from a power supply. [Figure 3] FIG. 3 is a diagram for explaining an example of the operation of the backup power supply circuit when the supply of power supply voltage from the power supply is cut off. [Figure 4] FIG. 4 is a block diagram of a sensing circuit according to one embodiment of the present disclosure. [Figure 5] FIG. 5 is a waveform diagram for explaining an example of the operation of the detection circuit according to the embodiment. [Figure 6] FIG. 6 is a waveform diagram for explaining an example of the operation of the detection circuit according to the embodiment.

[0009] [Detailed explanation] (overview) A summary of some exemplary embodiments of the present disclosure is provided. This summary is intended to provide a simplified overview of some concepts of one or more embodiments in order to provide a basic understanding of the embodiments as a prelude to the more detailed description that follows. It is not intended to limit the scope of the invention or disclosure. This summary is not an exhaustive overview of all possible embodiments, and is not intended to identify key elements of all embodiments or to delineate the scope of some or all aspects. For convenience, the term "one embodiment" may refer to one embodiment (example or variant) or multiple embodiments (examples or variants) disclosed herein.

[0010] A detection circuit according to one embodiment includes a current source that sources a constant current to a capacitor or sinks a constant current from the capacitor; a voltage measuring device that measures the voltage of the capacitor at three or more timing points when the constant current is sourced to the capacitor by the current source or when the constant current is sunk from the capacitor by the current source; a calculation unit that approximates the measurement results of the voltage of the capacitor at the three or more timing points to a linear line and calculates the slope of the linear line; and a detection unit that detects the state of the capacitor based on the slope of the linear line calculated by the calculation unit.

[0011] This configuration makes it possible to accurately detect the state of the capacitor.

[0012] In one embodiment, the detection unit may detect the capacitance value of the capacitor based on the slope of the linear line.

[0013] In one embodiment, the detection circuit may further include a memory unit that stores the measurement results. The current source may sink a constant current from a capacitor charged with an initial voltage. The voltage measuring device may measure the voltage of the capacitor at a timing different from the timing corresponding to the measurement results stored in the memory unit, based on the timing when the current source starts to sink the constant current. The calculation unit may approximate the measurement results stored in the memory unit and the measurement results of the capacitor voltage at the different timing to a linear line and calculate the slope of the linear line.

[0014] In one embodiment, the voltage measurement device may include an A / D converter that converts the voltage of the capacitor into digital data at regular time intervals.

[0015] A power supply circuit according to one embodiment may include a backup power supply circuit having the detection circuit described above, and a capacitor. The backup power supply circuit may charge the capacitor and supply an output voltage corresponding to a power supply voltage from a power supply to a load, and when the supply of power supply voltage from the power supply is cut off, may supply an output voltage corresponding to the voltage of the charged capacitor to the load.

[0016] In one embodiment, the backup power supply circuit may have a connection pin to which a capacitor is connected, and the capacitor may be charged via the connection pin. The detection unit may detect the connection state between the capacitor and the connection pin based on the slope of the linear line.

[0017] In one embodiment, the backup power supply circuit may include a DC / DC converter. The DC / DC converter may be configured to boost a voltage corresponding to a power supply voltage and supply the boosted voltage to the capacitor to charge the capacitor. The current source may sink a constant current from the capacitor. The voltage measuring device may measure the voltage of the capacitor at three or more points in time while the constant current is being sunk from the capacitor by the current source.

[0018] In one embodiment, the current source may sink a constant current from the capacitor so that the voltage on the capacitor does not fall below a predetermined lower limit voltage, which may be the voltage on the capacitor at which the backup power supply circuit can supply an output voltage to the load that corresponds to the voltage on the capacitor to supply the minimum amount of power required by the load.

[0019] In one embodiment, the DC / DC converter may be further configured to step down the voltage of the capacitor, and when the supply of power supply voltage from the power source is cut off, the backup power supply circuit may supply an output voltage to the load that corresponds to the voltage stepped down by the DC / DC converter.

[0020] A data storage system according to one embodiment may include the power supply circuit described above and a data storage device as a load to which the output voltage is supplied from the power supply circuit.

[0021] A detection method according to one embodiment includes a current source sourcing a constant current to a capacitor or sinking a constant current from the capacitor; a voltage measuring device measuring the voltage of the capacitor at three or more timing points when the constant current is being sourced to or sunk from the capacitor by the current source; a processor approximating the measurement results of the voltage of the capacitor at the three or more timing points to a linear line and calculating the slope of the linear line; and detecting the state of the capacitor based on the calculated slope of the linear line.

[0022] This configuration makes it possible to accurately detect the state of the capacitor.

[0023] (Embodiment) Preferred embodiments will be described below with reference to the drawings. The same or equivalent components, parts, and processes shown in each drawing will be given the same reference numerals, and redundant explanations will be omitted as appropriate. Furthermore, the embodiments are examples and do not limit the disclosure and invention, and all features and combinations thereof described in the embodiments are not necessarily essential to the disclosure and invention.

[0024] In this specification, "component A is connected to component B" includes not only a case where component A and component B are directly physically connected, but also a case where component A and component B are indirectly connected via other components that do not substantially affect the electrical connection state between them or that do not impair the function or effect achieved by their combination.

[0025] Similarly, "component C is connected (provided) between component A and component B" includes not only a case where component A and component C, or component B and component C, are directly connected, but also a case where they are indirectly connected via other components that do not substantially affect the electrical connection state between them or that do not impair the function or effect achieved by their combination.

[0026] In addition, in this specification, symbols attached to electrical signals such as voltage signals and current signals, or circuit elements such as resistors, capacitors, and inductors, represent the respective voltage values, current values, or circuit constants (resistance values, capacitance values, inductances) as necessary.

[0027] 1 is a block diagram of a data storage system 1 according to an embodiment of the present disclosure. The data storage system 1 mainly comprises a power supply circuit 2, a power supply 20, a load 22, capacitors C1 to C4, and an inductor L1. The data storage system 1 according to this embodiment has a power loss protection function called PLP (Power Loss Protection).

[0028] The load 22 may be any device or circuit that operates by receiving a supply of power. The load 22 may be a data storage device, such as an SSD (Solid State Drive). In this embodiment, an example in which the load 22 is a data storage device will be described.

[0029] The power supply circuit 2 outputs an output voltage V OUT It supplies the output voltage V OUT The power supply circuit 2 includes a backup power supply circuit 10 and a backup capacitor C BU It has.

[0030] The backup power supply circuit 10 is provided between a power supply 20 and a load 22. The backup power supply circuit 10 includes a backup capacitor C BU and the power supply voltage V from power supply 20 IN Output voltage V according to OUT is supplied to the load 22.

[0031] The backup power supply circuit 10 receives a power supply voltage V IN When the power supply is lost, the charged backup capacitor C BU Charging voltage V STR Output voltage V according to OUTTo be more specific, the backup power supply circuit 10 supplies a voltage V DC Output voltage V according to OUT is supplied to the load 22.

[0032] The backup power supply circuit 10 of this embodiment includes a switch controller 12, a DC / DC converter 14, a converter controller 16, a detection circuit 18, switches SW1 and SW2, an input pin IN, an output pin VBUS, a storage pin VSTR (connection pin), a ground pin GND, and pins VBBIN, SW, and BST.

[0033] Backup capacitor C BU is connected to a storage pin VSTR. As will be described later, the backup power supply circuit 10 supplies a backup capacitor C BU Charge the battery.

[0034] The input pin IN is connected to the power supply 20 and receives the power supply voltage V IN An external capacitor C1 is connected to the input pin IN. The output pin VBUS is connected to the load 22 and outputs an output voltage V OUT An external capacitor C2 is connected to the output pin VBUS.

[0035] The switch SW1 is provided between the input pin IN and the output pin VBUS. The switch SW1 may be, for example, an electronic fuse configured using a MOS (Metal Oxide Semiconductor) transistor.

[0036] The switch SW2 is provided between the output pin VBUS and the pin VBBIN and may be configured, for example, with an N-channel MOS transistor.

[0037] The switch controller 12 controls the on / off of the switches SW1 and SW2. The switch controller 12 according to this embodiment controls the on / off of the switch SW1 using a signal S1, and controls the on / off of the switch SW2 using a signal S2. The switch controller 12 receives a power supply voltage V from a power supply 20. IN The switches SW1 and SW2 can be controlled to be on or off depending on whether or not the power supply is supplied.

[0038] For example, the switch controller 12 may receive a power supply voltage V IN When the voltage at the input pin IN is equal to the power supply voltage V IN On the other hand, the switch controller 12 may turn on the power supply voltage V IN When there is no power supply and the voltage at the input pin IN is 0 (or the supply voltage V IN If the voltage Vcc is sufficiently lower than Vcc, the switch SW1 may be turned off and the switch SW2 may be turned on.

[0039] In the example shown in FIG. 1, the switch controller 12 is connected to the input pin VIN, but the switch controller 12 may control the on / off of the switches SW1 and SW2 based on, for example, a voltage obtained by dividing the voltage of the input pin VIN.

[0040] The DC / DC converter 14 is configured to function as both a step-up converter and a step-down converter. The configuration of the DC / DC converter 14 is not particularly limited. The DC / DC converter 14 may have various known circuit configurations, and specifically may be configured by combining a plurality of MOS transistors, for example, by using high-side transistors and low-side transistors. The DC / DC converter 14 is connected to a storage pin VSTR, a ground pin GND, and pins BST and SW.

[0041] For example, when DC / DC converter 14 functions as a step-down converter, pin BST may be used to increase the gate voltage of the high-side transistor of DC / DC converter 14 to turn on the high-side transistor. Note that when DC / DC converter 14 functions as a step-up converter, pin BST does not need to be used.

[0042] When the DC / DC converter 14 functions as a boost converter, the DC / DC converter 14 IN Voltage V according to DC (voltage at pin SW) is boosted to the boosted charging voltage V STR backup capacitor C BU This supplies the backup capacitor C BU When the DC / DC converter 14 functions as a step-down converter, the DC / DC converter 14 charges the backup capacitor C BU Charging voltage V STR is stepped down to voltage V DC Generate.

[0043] The converter controller 16 uses the signal S3 to control the operation of the DC / DC converter 14. Specifically, the converter controller 16 switches the function of the DC / DC converter 14 between a step-up converter and a step-down converter. The converter controller 16 converts the power supply voltage V IN The function of the DC / DC converter 14 may be switched depending on whether or not the power supply is supplied, more specifically, depending on the voltage at the input pin IN.

[0044] The converter controller 16 receives the power supply voltage V from the power supply 20. IN When the voltage at the input pin IN is equal to the power supply voltage V IN On the other hand, the converter controller 16 controls the power supply voltage V IN When there is no power supply and the voltage at the input pin IN is 0 (or the supply voltage V INIf the voltage Vcc is sufficiently lower than 1 / 2 V, DC / DC converter 14 may function as a step-down converter.

[0045] In the example shown in FIG. 1, the converter controller 16 is connected to the input pin VIN, but the converter controller 16 may switch the function of the DC / DC converter 14 based on, for example, a voltage obtained by dividing the voltage at the input pin VIN.

[0046] The detection circuit 18 is connected to a backup capacitor C BU Charging voltage V STR Based on the measurement results, the backup capacitor C BU The detection circuit 18 detects the state of the storage pin VSTR and the ground pin GND. The configuration and function of the detection circuit 18 will be described in detail later. The operation of the detection circuit 18 may be started or stopped based on an instruction from a control circuit (not shown), for example. When the detection circuit 18 operates, the DC / DC converter 14 may be disabled.

[0047] The operation frequency of the detection circuit 18 is not particularly limited, but may be, for example, about once a day, about once a month, about once every six months, or about once a year. Different operations of the detection circuit 18 may be performed at frequencies according to their contents. For example, one operation of the detection circuit 18 may be performed about once a day, and another operation of the detection circuit 18 may be performed about once every six months.

[0048] An external capacitor C3 is connected to the pin VBBIN. An external capacitor C4 is provided between the pin BST and the pin SW. An external inductor L1 is provided between the pin SW and the pin VBBIN. The ground pin GND is grounded.

[0049] Figure 2 shows the power supply voltage V IN1 is a diagram illustrating an example of the operation of the backup power supply circuit 10 when an output voltage V is supplied from the power supply 20 to the load 22. OUT and supplies a backup capacitor C BU Here, the switches SW1 and SW2 are both on.

[0050] Power is supplied to the load 22 from the power supply 20 through a path P1. The path P1 is a path from the power supply 20 to the load 22 that passes through the input pin IN, the switch SW1, and the output pin VBUS in this order. The load 22 is supplied with a power supply voltage V IN Output voltage V according to OUT At this time, the output voltage V OUT is the power supply voltage V IN may be substantially the same voltage as

[0051] Backup capacitor C BU Power is supplied to the backup capacitor C from the power supply 20 via a path P2. BU The path P2 is connected from the power supply 20 to the backup capacitor C through the input pin IN, the switch SW1, the switch SW2, the pin VBBIN, the inductor L1, the pin SW, the DC / DC converter 14, and the storage pin VSTR in this order. BU This is the route to.

[0052] In detail, the DC / DC converter 14 converts the power supply voltage V IN Voltage V according to DC is boosted to the charging voltage V STR Generates a backup capacitor C BU is the charging voltage V STR is supplied to the battery.

[0053] Figure 3 shows the power supply voltage V IN 1 is a diagram illustrating an example of the operation of the backup power supply circuit 10 when the power supply 20 is lost for some reason and the power supply voltage VIN If power is not supplied to the load 22, data stored in the data storage device of the load 22 may be lost.

[0054] In this embodiment, the backup power supply circuit 10 operates at a power supply voltage V IN In response to the loss of the supply of the backup capacitor C BU Charging voltage V STR This reduces power loss in the data storage device of the load 22.

[0055] In detail, the switch controller 12 controls the power supply voltage V IN In response to the loss of the supply of DC / DC converter 14, switch SW1 is switched off and switch SW2 is kept on. Converter controller 16 switches the function of DC / DC converter 14 to a step-down converter.

[0056] The load 22 is connected to a backup capacitor C BU Charging voltage V STR The path P3 passes through the storage pin VSTR, the DC / DC converter 14, the pin SW, the inductor L1, the pin VBBIN, the switch SW2, and the output pin VBUS in this order, and then the backup capacitor C BU The path is from the load 22 to the load 23.

[0057] The DC / DC converter 14 is connected to a backup capacitor C BU Charging voltage V STR The voltage V DC The load 22 generates a voltage V DC Output voltage V according to OUT This supplies power to the power supply voltage V IN Therefore, even if the supply of power is cut off, it is possible to supply power to the load 22.

[0058] 4 is a block diagram of the detection circuit 18 according to this embodiment. The detection circuit 18 according to this embodiment mainly includes a current source 180, a voltage measuring device 182, a storage unit 184, and a processing unit 190. The detection circuit 18 may also include a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), and the like, as necessary.

[0059] The current source 180 according to this embodiment includes a backup capacitor C BU The constant current Is is sunk from the backup capacitor C BU The current source 180 according to this embodiment is connected to the storage pin VSTR via the initial voltage V INIT Charging voltage V STR Backup capacitor C charged by BU A constant current Is is sinked from the

[0060] The current source 180 is connected to a backup capacitor C BU Charging voltage V STR The backup capacitor C BU The backup power supply circuit 10 may sink a constant current Is from the backup capacitor C BU Charging voltage V STR Output voltage V according to OUT to the load 22, the backup capacitor C BU Charging voltage V STR As a result, the power supply voltage V IN When the supply of the power source is cut off, it is possible to reliably supply the required amount of power to the load 22.

[0061] The voltage measuring device 182 measures the voltage of the backup capacitor C BU Charging voltage V STR and transmits data D1 indicating the measurement result to the storage unit 184. The voltage measurement device 182 measures the voltage of the backup capacitor CBU Charging voltage V STR The A / D converter may include an A / D converter that converts the charging voltage V into digital data in response to a clock signal. STR is converted into digital data.

[0062] The voltage measuring device 182 according to this embodiment is configured such that a constant current Is is supplied to the backup capacitor C BU When the power supply is sinking from the backup capacitor C BU Charging voltage V STR is measured at three or more timing points. At this time, the interval between two adjacent timing points among the three or more timing points may be constant or may be variable. The voltage measuring device 182 according to this embodiment measures the charging voltage V at constant time intervals. STR Measure.

[0063] The memory unit 184 stores the charging voltage V STR The voltage measurement device 182 measures the voltage of the backup capacitor C at a timing different from the timing corresponding to the measurement result stored in the storage unit 184, based on the timing when the current source 180 starts to sink the constant current Is. BU Charging voltage V STR At this time, the backup capacitor C BU Charging voltage V STR The number of timings for measuring the voltage of the backup capacitor C is not particularly limited, but the voltage measuring device 182 measures the voltage of the backup capacitor C at three or more different timings. BU Charging voltage V STR may be measured.

[0064] The storage unit 184 stores various types of information. For example, the storage unit 184 stores the backup capacitor C BU Charging voltage V STR The measurement results of the charging voltage V and the results of various processes performed by the processing unit 190 may be stored. STR The data D2 including the measurement results is transmitted to the processing unit 190.

[0065] The processing unit 190 executes various processes. The processing unit 190 includes a calculation unit 192 and a detection unit 194. The functions of the processing unit 190 may be executed by, for example, a CPU.

[0066] Calculation unit 192 approximates the measurement results at three or more timing points by voltage measuring device 182 to a linear line and calculates the slope of the linear line. Data D3 indicating the slope is transmitted to detection unit 194. For example, calculation unit 192 plots the measurement results at three or more points with the horizontal axis representing the measurement time and the vertical axis representing the measurement result, and approximates these measurement results to a linear line. The method of approximating the linear line is not particularly limited, but may be, for example, the least squares method.

[0067] As described above, the voltage measuring device 182 measures the voltage of the backup capacitor C at a timing different from the timing corresponding to the measurement result stored in the memory unit 184. BU Charging voltage V STR In this case, the calculation unit 192 may measure the backup capacitor C BU Charging voltage V STR The measurement results and the measurement results may be approximated to a linear line, and the slope of the linear line may be calculated. This allows the calculation section 192 to more accurately calculate the slope by linearly approximating the measurement results.

[0068] The detection unit 194 detects the backup capacitor C BU The detection unit 194 detects the state of the backup capacitor C BU and the capacitance value of the backup capacitor C BU The connection status of the backup capacitor C BU The connection state of the backup capacitor C BU and the storage pin VSTR.

[0069] Capacitor C BU The capacitance value is calculated by the constant current Is, measurement time t, and charging voltage VSTR Using this, it is expressed by the following equation: C BU =Is×Δt / ΔV STR ···(1)

[0070] In equation (1), Δt / ΔV on the right side STR corresponds to the inverse of the slope of the linear line, and the value of the constant current Is is known. Therefore, the detection unit 194 determines the capacitance of the backup capacitor C BU The capacitance value can be calculated.

[0071] In this embodiment, the measurement results of three or more points are approximated to a linear line, so even if random noise is present in each measurement result, the random noise is averaged. Therefore, by using the slope of the linear line on which the random noise is averaged, it is possible to accurately estimate the backup capacitor C BU Therefore, it is possible to detect the capacitance value of the backup capacitor C BU This makes it possible to improve the accuracy of repeated measurements of the capacitance value.

[0072] Backup capacitor C BU As the backup capacitor C deteriorates over time, its capacitance value changes. BU may deteriorate over time, for example, on a time scale of about one month. For this reason, the backup capacitor C BU Therefore, the user must ensure that the sensed backup capacitor C BU Check the capacitance value of the backup capacitor C BU It can be determined whether it is available or not.

[0073] The detection unit 194 detects the backup capacitor C BU Based on the capacitance value of the backup capacitor C BU For example, the detection unit 194 may determine whether the detected backup capacitor C BUIf the capacitance value of is lower (or higher) than the reference value, the backup capacitor C BU is not available and the detected backup capacitor C BU If the capacitance value of is less than (or more than) the reference value, the backup capacitor C BU can be judged to be usable.

[0074] In addition, a backup capacitor C externally attached to the backup power supply circuit 10 BU The connection status of the backup capacitor C BU For example, a fault may occur in the backup capacitor C BU Even if a disconnection occurs, residual capacity may remain, and the slope of the linear line corresponding to this capacity may be obtained. For example, the slope of the linear line may be obtained by BU The slope may be extremely different (for example, extremely low) from the slope obtained from the measurement results when there is no abnormality in the connection state.

[0075] The detection unit 194 detects the backup capacitor C BU For example, if the slope of the linear line is lower (or higher) than the threshold value for determining the connection state, the detection unit 194 detects an abnormality in the connection state of the backup capacitor C BU Alternatively, if the capacitance value obtained from the slope of the linear line is lower (or higher) than the reference capacitance value for determining the connection state, the detection unit 194 may detect that there is an abnormality in the connection state of the backup capacitor C BU It may be possible to detect a break in the

[0076] The information acquired by the calculation unit 192 and the detection unit 194 described above (for example, the slope of the linear line, the backup capacitor C BU The capacitance value of the backup capacitor C BUThe data (presence or absence of an abnormality in the connection state of the backup capacitor C) may be stored in the storage unit 184 as data D4 in association with the date and time information. BU You can check the status etc.

[0077] 5 is a waveform diagram for explaining an example of the operation of the detection circuit 18 according to this embodiment. In FIG. 5, the horizontal axis represents the measurement time, and the vertical axis represents the charging voltage V STR Shows.

[0078] Voltage waveform A is the charging voltage V STR Before timing t0, the backup capacitor C BU is the initial voltage V INIT At time t0, the current source 180 charges the backup capacitor C BU The backup capacitor C starts to sink a constant current Is from the BU is discharged and the charging voltage V STR decreases linearly.

[0079] Voltage measurement device 182 measures the current source 180 when the backup capacitor C BU After starting to sink a constant current Is from the STR In FIG. 5, the charging voltage measured at seven timings from t1 to t7 is indicated by black circles. Although FIG. 5 shows the measurement results at seven timings, the charging voltage V STR may be measured.

[0080] The current source 180 stops sinking the constant current Is (timing t8) in response to the passage of time T2 since starting to sink the constant current Is. STR is the end voltage V END It should be noted that while current source 180 is sinking constant current Is (timing t0 to t8), DC / DC converter 14 may be disabled.

[0081] The calculation unit 192 approximates the seven measurement results obtained by the voltage measuring device 182 to a linear line. In FIG. 5, the dashed line B1 is an example of the linear line approximated by the calculation unit 192. The detection unit 194 calculates the voltage of the backup capacitor C based on the slope of the line B1. BU The measurement results at times t1 to t7 show that the slope of the line B1 and the state of the backup capacitor C BU The detection results of the above state are stored in the storage unit 184 in association with date and time information.

[0082] Here, the time interval T1 depends on the operating speed (frequency of the clock signal) of the A / D converter of the voltage measuring device 182. When the time interval T1 is fixed, the initial voltage V INIT and the end voltage V END The larger the difference ΔV between the STR It is possible to measure

[0083] On the other hand, the charging voltage V STR In order to be able to supply sufficient power to the load 22 even if the power supply 20 is lost during the measurement of BU Therefore, the final voltage V END is preferably equal to or greater than the lower limit voltage. STR Even if the power supply 20 is lost during the measurement, the backup power supply circuit 10 can supply the required amount of power to the load 22.

[0084] In addition, the charging voltage V STR is the final voltage V END After the voltage drops to INIT and a backup capacitor C BU may be recharged.

[0085] 6 is a waveform diagram for explaining an example of the operation of the detection circuit 18 according to this embodiment. In FIG. 6, the horizontal axis represents the measurement time, and the vertical axis represents the charging voltage VSTR is shown. Also, in FIG. 6, in addition to the voltage waveform A and the measurement results at timings t1 to t7 described with reference to FIG. 5 (hereinafter, these are also collectively referred to as the "first measurement results"), the newly obtained measurement results are shown as white circles (timing t 11 ~t 16 ).

[0086] As described above, the voltage measuring device 182 can measure the charging voltage V STR at different timings with reference to the start of the sink of the constant current Is by the current source 180 (timing t0). Specifically, the voltage measuring device 182 measures the charging voltage V 11 ~t 16 at timings that are ΔT1 delayed from timings t1 to t6. Thereby, the voltage measuring device 182 can measure the charging voltage V STR at six new timings. Note that ΔT1 may be 0 < ΔT1 < T1, and may be, for example, about T1 / 2. STR

[0087] The second measurement date on which the measurement at timing t 11 ~t 16 is performed may be, for example, the day after the first measurement date on which the measurement at timing t 11 ~t 16 is performed. Therefore, the interval between the first measurement date and the second measurement date is an interval such that the deterioration in the backup capacitor C BU can be ignored. Therefore, the calculation unit 192 can approximate the first measurement results and the measurement results at timings t 11 ~t 16 (hereinafter, these are also collectively referred to as the "second measurement results") to a first-order straight line and calculate its slope.

[0088] The straight line B2 shown in FIG. 6 is the first-order straight line obtained in this way. The detection unit 194 determines the backup capacitor C BU ​In this case, the detection unit 194 can use more measurement results (a total of 13 first and second measurement results) than when using only the seven first measurement results, and therefore can more accurately detect the state of the backup capacitor C BU Although the example in which two measurement results are used has been explained here, the state of the backup capacitor C BU The results of three or more measurements may be used within an allowable range for deterioration over time.

[0089] In addition, in Figure 6, an example where measurements are made at six new timing points is explained. STR The new timing for measuring the charging voltage V may be five points or less, or seven points or more. STR By measuring the backup capacitor C only at three or more new timing points, BU It is also possible to detect the state of

[0090] According to the power supply circuit 2 of this embodiment, the voltage measuring device 182 detects whether the constant current Is is supplied to the backup capacitor C BU When the power supply is sinking from the backup capacitor C BU Charging voltage V STR The calculation unit 192 measures the backup capacitor C BU Charging voltage V STR The measurement result is approximated to a linear line, and the slope of the linear line is calculated. Based on the slope calculated by the calculation unit 192, the detection unit 194 calculates the voltage of the backup capacitor C BU Detect the state of

[0091] According to this aspect, the backup capacitor C BU Charging voltage V STRis measured, and the measurement result is approximated to a linear line, so even if the measurement result contains random noise, the random noise is averaged. Therefore, by using the slope of the linear line that averages the random noise, it is possible to accurately calculate the backup capacitor C BU It is possible to detect the state of

[0092] (First Modification) In the above embodiment, the backup capacitor C BU The charge voltage V when sinking a constant current Is from STR Using the measurement results, the backup capacitor C BU In the above example, the current source 180 detects the state of the backup capacitor C BU In this case, the calculation unit 192 calculates the charging voltage V STR The measurement result is approximated to a linear line, and the detection unit 194 calculates the backup capacitor C BU In this case, the backup capacitor C BU Charging voltage V STR It should be noted that the upper limit of is the power supply voltage. In applications where a capacitor is charged by the power supply voltage, such a method of detecting the state of the capacitor is also useful.

[0093] (Second Modification) In the above embodiment, the detection circuit 18 detects the power supply voltage V IN a backup capacitor C for powering the load 22 when the supply to BU However, the detection circuit 18 is not limited to this and may be used to detect the states of various capacitors.

[0094] (Third Modification) In the above embodiment, an example has been described in which the current source 180 stops sinking the constant current Is in response to the lapse of a predetermined time T2 after starting to sink the constant current Is. However, the current source 180 is not limited to this. For example, the voltage measuring device 182 may measure the charging voltage V at a predetermined number of timings.STR or the charging voltage V STR The sinking of the constant current Is may be stopped in response to, for example, the voltage value of the constant current Is reaching a predetermined value.

[0095] (Application example) In the above embodiment, the detection circuit 18 mainly detects the voltage of the backup capacitor C when the backup power supply circuit 10 is supplying power from the power supply 20 to the load 22. BU In the above example, the detection circuit 18 detects the state of the backup capacitor C BU This eliminates the need to consider the loss of the power supply 20, so the charging voltage V STR As a result, the charging voltage V STR This allows for more accurate measurement of the backup capacitor C BU It is possible to detect the state of such a backup capacitor C BU The detection of this state may be performed, for example, approximately once every six months.

[0096] (supplement) Although the embodiments of the present disclosure have been described using specific terms, this description is merely an example to facilitate understanding and does not limit the scope of the present disclosure or the claims, and the scope of the present invention is defined by the claims. Furthermore, not only the embodiments but also embodiments, examples, and modifications not described herein are included in the scope of the present invention.

[0097] (Addendum) One aspect of the technology disclosed in this specification can be understood as follows.

[0098] (Item 1) a current source for sourcing or sinking a constant current to or from the capacitor; a voltage measuring device that measures the voltage of the capacitor at three or more timing points when the current source is sourcing a constant current to the capacitor or when the current source is sinking a constant current from the capacitor; a calculation unit that approximates the measurement results of the voltage of the capacitor at the three or more timing points to a linear line and calculates the slope of the linear line; a detection unit that detects a state of the capacitor based on the slope of the linear line calculated by the calculation unit, Detection circuit.

[0099] (Item 2) The detection unit detects a capacitance value of the capacitor based on a slope of the linear line. Item 1. The detection circuit according to item 1.

[0100] (Item 3) Further, a storage unit for storing the measurement results is provided, the current source sinks a constant current from a capacitor charged with an initial voltage; the voltage measuring device measures the voltage of the capacitor at a timing different from the timing corresponding to the measurement result stored in the storage unit, based on the timing at which the current source starts to sink the constant current; the calculation unit approximates the measurement results stored in the storage unit and the measurement results of the voltage of the capacitor at the different timings to a linear line, and calculates a slope of the linear line. Item 3. The detection circuit according to item 1 or 2.

[0101] (Item 4) The voltage measuring device has an A / D converter that converts the voltage of the capacitor into digital data at regular time intervals. 4. A detection circuit according to any one of items 1 to 3.

[0102] (Item 5) A backup power supply circuit having the detection circuit according to any one of items 1 to 4; the capacitor, the backup power supply circuit charges the capacitor and supplies an output voltage corresponding to a power supply voltage from a power supply to a load, and when the supply of the power supply voltage from the power supply is stopped, supplies an output voltage corresponding to the voltage of the charged capacitor to the load. power circuit.

[0103] (Item 6) the backup power supply circuit has a connection pin to which the capacitor is connected, and charges the capacitor via the connection pin; the detection unit detects a connection state between the capacitor and the connection pin based on a slope of the linear line; Item 5. The power supply circuit according to item 5.

[0104] (Item 7) the backup power supply circuit has a DC / DC converter, the DC / DC converter is configured to boost a voltage corresponding to the power supply voltage and supply the boosted voltage to the capacitor, thereby charging the capacitor; the current source sinks a constant current from the capacitor; the voltage measuring device measures the voltage of the capacitor at three or more timing points when the current source is sinking a constant current from the capacitor; 7. The power supply circuit according to item 5 or 6.

[0105] (Item 8) the current source sinks a constant current from the capacitor so that the voltage on the capacitor does not fall below a predetermined lower voltage limit; the lower limit voltage is the voltage of the capacitor when the backup power supply circuit can supply the load with an output voltage corresponding to the voltage of the capacitor and supply the load with a minimum amount of power required; Item 7. The power supply circuit according to item 7.

[0106] (Item 9) the DC / DC converter is further configured to be able to step down the voltage of the capacitor; the backup power supply circuit supplies to the load an output voltage corresponding to the voltage stepped down by the DC / DC converter when the supply of the power supply voltage from the power supply is cut off; Item 8. The power supply circuit according to item 8.

[0107] (Item 10) The power supply circuit according to any one of items 5 to 9, a data storage device as the load to which an output voltage is supplied from the power supply circuit, Data storage system.

[0108] (Item 11) a current source sourcing or sinking a constant current to or from a capacitor; a voltage measuring device measuring the voltage of the capacitor at three or more timing points when the current source is sourcing a constant current to the capacitor or when the current source is sinking a constant current from the capacitor; The processor: approximating the measurement results of the voltage of the capacitor at the three or more timing points to a linear line and calculating the slope of the linear line; and detecting a state of the capacitor based on the calculated slope of the linear line. Detection method. [Explanation of symbols]

[0109] 1 data storage system, 2 power supply circuit, 10 backup power supply circuit, 12 switch controller, 14 DC / DC converter, 16 converter controller, 18 detection circuit, 20 power supply, 22 load, 180 current source, 182 voltage measuring device, 184 memory unit, 190 processing unit, 192 calculation unit, 194 detection unit, SW1, SW2 switches, IN input pin, VBUS output pin, VSTR storage pin, GND ground pin, VBBIN, BST, SW pins, CBU Backup capacitor, C1~C3 capacitors, L1 inductor.

Claims

1. a current source for sourcing or sinking a constant current to or from the capacitor; a voltage measuring device that measures the voltage of the capacitor at three or more timing points when the current source is sourcing a constant current to the capacitor or when the current source is sinking a constant current from the capacitor; a calculation unit that approximates the measurement results of the voltage of the capacitor at the three or more timing points to a linear line and calculates the slope of the linear line; a detection unit that detects a state of the capacitor based on the slope of the linear line calculated by the calculation unit, Detection circuit.

2. The detection unit detects a capacitance value of the capacitor based on a slope of the linear line. The detection circuit of claim 1 .

3. Further, a storage unit for storing the measurement results is provided, the current source sinks a constant current from a capacitor charged with an initial voltage; the voltage measuring device measures the voltage of the capacitor at a timing different from the timing corresponding to the measurement result stored in the storage unit, based on the timing at which the current source starts to sink the constant current; the calculation unit approximates the measurement results stored in the storage unit and the measurement results of the voltage of the capacitor at the different timings to a linear line, and calculates a slope of the linear line. The detection circuit of claim 1 .

4. The voltage measuring device has an A / D converter that converts the voltage of the capacitor into digital data at regular time intervals. The detection circuit of claim 1 .

5. a backup power supply circuit having the detection circuit according to any one of claims 1 to 4; the capacitor, the backup power supply circuit charges the capacitor and supplies an output voltage corresponding to a power supply voltage from a power supply to a load, and when the supply of the power supply voltage from the power supply is stopped, supplies an output voltage corresponding to the voltage of the charged capacitor to the load. power circuit.

6. the backup power supply circuit has a connection pin to which the capacitor is connected, and charges the capacitor via the connection pin; the detection unit detects a connection state between the capacitor and the connection pin based on a slope of the linear line; 6. The power supply circuit according to claim 5.

7. the backup power supply circuit has a DC / DC converter, the DC / DC converter is configured to boost a voltage corresponding to the power supply voltage and supply the boosted voltage to the capacitor, thereby charging the capacitor; the current source sinks a constant current from the capacitor; the voltage measuring device measures the voltage of the capacitor at three or more timing points when the current source is sinking a constant current from the capacitor; 6. The power supply circuit according to claim 5.

8. the current source sinks a constant current from the capacitor so that the voltage on the capacitor does not fall below a predetermined lower voltage limit; the lower limit voltage is the voltage of the capacitor when the backup power supply circuit can supply the load with an output voltage corresponding to the voltage of the capacitor and supply the load with a minimum amount of power required; 8. The power supply circuit according to claim 7.

9. the DC / DC converter is further configured to be able to step down the voltage of the capacitor; the backup power supply circuit supplies to the load an output voltage corresponding to the voltage stepped down by the DC / DC converter when the supply of the power supply voltage from the power supply is cut off; 9. The power supply circuit according to claim 8.

10. a power supply circuit according to claim 5; a data storage device as the load to which an output voltage is supplied from the power supply circuit, Data storage system.

11. a current source sourcing or sinking a constant current to or from a capacitor; a voltage measuring device measuring the voltage of the capacitor at three or more timing points when the current source is sourcing a constant current to the capacitor or when the current source is sinking a constant current from the capacitor; The processor: approximating the measurement results of the voltage of the capacitor at the three or more timing points to a linear line and calculating the slope of the linear line; and detecting a state of the capacitor based on the calculated slope of the linear line. Detection method.

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