Circuit device and electronic apparatus

Abstract

To provide a circuit device and the like capable of obtaining a charging capacity of a battery by low-load processing.SOLUTION: The circuit device 20 includes the charging circuit 30 that charges the battery 10, the voltage measurement circuit 40 that measures the battery voltage VBAT of the battery 10, the storage unit 60 that stores the weighting coefficient for the battery capacity in each voltage section of the plurality of voltage sections, and the control circuit 50 that performs the integration processing for the weighting coefficient based on the measurement result of the battery voltage VBAT by the voltage measurement circuit 40 and obtains the charge capacity of the battery 10 charged by the charging circuit 30 based on the result of the integration processing.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a circuit device, an electronic device, and the like. [Background technology]

[0002] Patent Document 1 discloses a charge / discharge control device that controls the charging and discharging of a battery and calculates the charge capacity of the battery. In Patent Document 1, the time from when the battery voltage exceeds the lower limit voltage value of the voltage section until it reaches the upper limit voltage value is measured for each voltage section, and the section charge capacity corresponding to each voltage section is calculated based on the product of the measured time and the charging current value. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-151144 Summary of the Invention [Problem to be solved by the invention]

[0004] For example, to calculate the charge capacity of a battery, it is necessary to provide a coulomb counter between the charging circuit device and the battery to calculate the amount of charge. However, providing such a coulomb counter hinders efforts to reduce the size and cost of electronic devices. Furthermore, in the aforementioned Patent Document 1, information on the battery capacity for each voltage range is not stored in a memory unit. Therefore, it is necessary to measure the time from when the voltage range's lower limit voltage is exceeded until the voltage reaches its upper limit voltage, as well as the charging current value, and to calculate the product of this time and the charging current value. As a result, it is not possible to calculate the charge capacity of batteries with various capacity characteristics using light-load processing. [Means for solving the problem]

[0005] One aspect of the present disclosure relates to a circuit device including a charging circuit that charges a battery, a voltage measurement circuit that measures the battery voltage of the battery, a memory unit that stores a weighting coefficient for battery capacity in each voltage interval of a plurality of voltage intervals, and a control circuit that performs an integration process for the weighting coefficient based on the measurement results of the battery voltage by the voltage measurement circuit, and determines the charge capacity of the battery charged by the charging circuit based on the results of the integration process.

[0006] Another aspect of the present disclosure relates to an electronic device including the circuit device described above and the battery. [Brief explanation of the drawings]

[0007] [Figure 1] 1 shows an example of the configuration of a circuit device and electronic equipment according to an embodiment of the present invention. [Figure 2] 1 shows detailed configuration examples of circuit devices and electronic devices. [Figure 3] An example of a charging circuit configuration. [Figure 4] FIG. 10 is an explanatory diagram illustrating storage of voltage section setting information and weighting coefficients in a storage unit. [Figure 5] FIG. [Figure 6] 4 is a flowchart illustrating the operation of the present embodiment. [Figure 7] An explanatory diagram of the internal resistance and open voltage of a battery. [Figure 8] FIG. 10 is an explanatory diagram of a method for eliminating the influence of internal resistance. [Figure 9] FIG. 1 is an explanatory diagram of a method for measuring internal resistance. [Figure 10] 4 is a flowchart illustrating a detailed operation of the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] The present embodiment will be described below. Note that the present embodiment described below does not unduly limit the content of the claims. Furthermore, not all of the configurations described in the present embodiment are necessarily essential components.

[0009] 1.Circuit devices, electronic equipment 1 shows an example of the configuration of a circuit device 20 and electronic device 2 according to this embodiment. The circuit device 20 includes a charging circuit 30, a voltage measurement circuit 40, a control circuit 50, and a storage unit 60. The electronic device 2 includes the circuit device 20 and a battery 10. The circuit device 20 and the electronic device 2 are not limited to the configuration shown in FIG. 2, and various modifications are possible, such as omitting some of the components or adding other components.

[0010] The electronic device 2 may be a hearable device such as a hearing aid or an earphone for listening to audio, or a wearable device. The earphone may be, for example, a wireless earphone. The electronic device 2 may be a head-mounted display, a portable communication terminal such as a smartphone or a mobile phone, a wristwatch, a biometric information measuring device, a shaver, an electric toothbrush, a wrist computer, a handheld terminal, or an in-vehicle device.

[0011] The circuit device 20 operates as a charging device that charges, for example, a battery 10. The circuit device 20 can be realized, for example, by an integrated circuit device (IC). The battery 10 to be charged is, for example, a secondary battery, such as a lithium-ion secondary battery, a nickel-metal hydride battery, or a nickel-cadmium battery. The battery 10 may also be realized by a supercapacitor. The battery 10 is connected to a terminal TBAT of the circuit device 20. The terminal TBAT is an external connection terminal, for example, a pad or package, of the circuit device 20, which is an IC. For example, in the pad region, a metal layer is exposed from a passivation film, which is an insulating layer, and this exposed metal layer forms a pad, which is a terminal of the circuit device 20. Note that the connection in this embodiment is an electrical connection. An electrical connection is a connection that allows electrical signals to be transmitted, and is a connection that enables information to be transmitted by electrical signals. The electrical connection may be a connection via a passive element, etc.

[0012] The charging circuit 30 charges the battery 10. For example, the charging circuit 30 charges the battery 10 with power received from a power supply voltage VCC supplied to a power supply node NIN. For example, the charging circuit 30 charges the battery 10 by generating a charging current ICH based on the power supply voltage VCC and supplying it to a node NB to charge the battery 10. Specifically, the charging circuit 30 charges the battery 10 using constant current charging or CCCV charging. Constant current charging is CC charging. In CCCV charging, the charging circuit 30 first performs constant current charging (CC charging) of the battery 10 and then switches to constant voltage charging (CV charging) to charge the battery 10. For example, the charging circuit 30 charges the battery 10 using constant current charging, and then switches from constant current charging to constant voltage charging when the battery voltage VBAT reaches a predetermined voltage. Note that the power received from the power supply voltage VCC may be power received via contactless power transmission as shown in FIG. 2 (described later) or power received via contactless power transmission via a wire. The power supply voltage VCC is, for example, 5V to 4V, and the battery voltage VBAT is, for example, 4.3V to 3.6V.

[0013] The voltage measurement circuit 40 measures the battery voltage VBAT. The battery voltage VBAT is, for example, the voltage of the positive electrode of the battery 10. For example, the voltage measurement circuit 40 measures the battery voltage VBAT at a node NB, which is a charging node of the battery 10. For example, the voltage measurement circuit 40 performs A / D conversion of the battery voltage VBAT and outputs the digital data of the battery voltage VBAT obtained by A / D conversion to the control circuit 50.

[0014] The memory unit 60 stores various information and is implemented by a memory circuit such as a memory or a register. The memory unit 60 stores a weighting coefficient for battery capacity for each of the multiple voltage sections. The unit of battery capacity is, for example, mAh. The voltage sections are sections into which the fluctuations of the battery voltage VBAT are divided. The voltage sections may be equally spaced or unequal. For example, the voltage sections may be spaced closer together in a range where the battery capacity changes significantly with respect to the battery voltage VBAT than in a range where the battery capacity changes less. For example, the voltage range of voltage section VI1 is narrower than the voltage range of voltage section VI2 because the battery capacity changes more significantly with respect to the battery voltage VBAT in voltage section VI1. The weighting coefficient indicates the proportion of the battery capacity estimated to be charged in each of the multiple voltage sections. For example, the weighting coefficient indicates the proportion of the battery capacity charged in each voltage section relative to the battery capacity at full charge. For example, the weighting coefficient is a coefficient assigned by weighting the percentage of the battery capacity charged in each of the multiple voltage sections, assuming that the battery capacity when fully charged is 100%. For example, the weighting coefficient for each of the multiple voltage sections is set based on the charging characteristics, which are the battery voltage-battery capacity characteristics, of the battery 10 used in the electronic device 2, and information on the set weighting coefficient is stored in the storage unit 60.

[0015] The control circuit 50 performs various control processes, arithmetic processes, and the like. For example, the control circuit 50 controls the charging circuit 30. The control circuit 50 can be realized by an ASIC (Application Specific Integrated Circuit) using automatic placement and routing such as a gate array, but may also be realized by a processor such as a DSP (Digital Signal Processor), a CPU (Central Processing Unit), or a microcontroller.

[0016] Then, based on the measurement result of the battery voltage VBAT by the voltage measurement circuit 40, the control circuit 50 performs an integration process on the weighting coefficient. For example, the control circuit 50 reads out the weighting coefficient of the voltage range to which the measured battery voltage VBAT belongs from the storage unit 60, and performs a process of integrating the read weighting coefficient. Then, based on the result of the integration process, the control circuit 50 obtains the charging capacity of the battery 10 charged by the charging circuit 30. For example, assume that the battery voltage VBAT measured when the charging of the battery 10 starts belongs to the i-th voltage range, and the battery voltage VBAT measured when the charging of the battery 10 ends belongs to the j-th voltage range. i and j are integers such that i < j. At this time, the control circuit 50 reads out the weighting coefficients of the i-th voltage range to the j-th voltage range from the storage unit 60 and performs an integration process to obtain the charging capacity of the battery 10 charged by the charging circuit 30. In this case, for the weighting coefficient in the i-th voltage range, an interpolation coefficient corresponding to the voltage ratio of the battery voltage VBAT (charging start voltage) within the i-th voltage range may be multiplied. Also, for the weighting coefficient in the j-th voltage range, an interpolation coefficient corresponding to the voltage ratio of the battery voltage VBAT (charging end voltage) within the j-th voltage range may be multiplied. Based on the charging capacity of the battery 10 obtained in this way, for example, an update process of the cycle time representing the number of charging times of the battery 10 is performed, or a notification process of displaying or notifying the charging capacity in the electronic device 2 is performed.

[0017] Fig. 2 shows a detailed configuration example of the circuit device 20 and electronic device 2 of this embodiment. Fig. 2 shows a configuration example for wireless charging, in which a battery 10 is charged based on power received by contactless power transmission. In Fig. 2, the circuit device 20 includes a power receiving circuit 70 and a power supply circuit 80 in addition to a charging circuit 30, a voltage measurement circuit 40, a control circuit 50, and a memory unit 60. Note that the circuit device 20 and the electronic device 2 are not limited to the configuration shown in Fig. 2, and various modifications are possible, such as omitting some of the components or adding other components.

[0018] The power receiving circuit 70 receives the transmitted power from the power transmitting device 14 without contact. That is, it receives power wirelessly. For example, a primary coil L1 is provided on the power transmitting device 14 side, and a secondary coil L2 is provided on the power receiving device side realized by the circuit device 20. The power transmitting device 14 is provided, for example, in a charging stand or charging case for charging the electronic device 2. A power transmitting driver of the power transmitting device 14 applies an AC voltage to the primary coil L1, thereby transmitting power from the primary coil L1 to the secondary coil L2. The power receiving circuit 70 receives power from the power transmitting device 14. Specifically, the power receiving circuit 70 converts the AC induced voltage of the secondary coil L2 into a rectified DC voltage. This conversion is performed by a rectifier circuit 72 included in the power receiving circuit 70. The rectifier circuit 72 can be realized, for example, by multiple transistors and diodes. The charging circuit 30 charges the battery 10 based on the rectified voltage, which is the power supply voltage VCC.

[0019] The voltage measurement circuit 40 includes an A / D conversion circuit 42. The A / D conversion circuit 42 performs A / D conversion of the battery voltage VBAT at the node NB, and outputs the digital data obtained by the A / D conversion to the control circuit 50.

[0020] The storage unit 60 includes a register unit 62 and a non-volatile memory 64. However, the storage unit 60 may be realized by either the register unit 62 or the non-volatile memory 64. For example, the non-volatile memory 64 may be provided outside the circuit device 20, in which case the storage unit 60 would include only the register unit 62.

[0021] The register unit 62 stores various types of information. The control circuit 50 operates by reading information such as data and commands stored in the register unit 62. The register unit 62 can be realized by, for example, a flip-flop circuit or a memory such as a RAM.

[0022] The nonvolatile memory 64 is a memory that can maintain its stored contents even without an external power supply. The nonvolatile memory 64 can be realized by, for example, an EEPROM (Electrically Erasable Programmable Read-Only Memory) that allows data to be electrically erased, or an OTP (One Time Programmable) memory that uses a FAMOS (Floating gate Avalanche injection MOS).

[0023] The register unit 62 stores various types of information by loading information read from, for example, the nonvolatile memory 64. Alternatively, an interface circuit (not shown) may be provided in the circuit device 20, and the register unit 62 may store information input from the outside via this interface circuit. Alternatively, a communication circuit (not shown) that communicates with the power transmitting device 14 may be provided in the circuit device 20, and the register unit 62 may store information received from the power transmitting device 14 via this communication circuit.

[0024] The power supply circuit 80 discharges the battery 10 and supplies a power supply voltage based on the discharging operation to the power supply target device 12. The power supply target device 12 is, for example, a processing device such as a microcomputer provided in the electronic device 2. Specifically, the power supply circuit 80 operates using the battery voltage VBAT of the battery 10 as a power supply voltage. The power supply circuit 80 outputs an output voltage VOUT based on the battery voltage VBAT as the power supply voltage for the power supply target device 12. For example, the power supply circuit 80 includes a charge pump circuit or a switching regulator circuit, and this charge pump circuit or switching regulator circuit performs a charge pump operation or a switching regulation operation to step down the battery voltage VBAT, and supplies the output voltage VOUT obtained by stepping down the battery voltage VBAT to the power supply target device 12.

[0025] The circuit device 20 is provided with a charging system circuit and a discharging system circuit. The charging system circuit operates based on received power and charges the battery 10, which is the charging target. For example, the charging system circuit receives received power from a power supply voltage VCC, operates based on the power supply voltage VCC, and charges the battery 10. On the other hand, the discharging system circuit operates based on the battery voltage VBAT of the battery 10. That is, each circuit provided in the discharging system circuit operates using the battery voltage VBAT as a power supply voltage. Furthermore, the power supply circuit 80 provided as the discharging system circuit outputs an output voltage VOUT based on the battery voltage VBAT as a power supply voltage for the power supply target device 12.

[0026] The register unit 62 is a discharge circuit. A charge control circuit and a discharge control circuit are provided as the control circuit 50. The register unit 62 and the discharge control circuit are capable of operating using the battery voltage VBAT as a power supply voltage even when power is not being received by the power receiving circuit 70.

[0027] FIG. 3 shows an example configuration of the charging circuit 30. As shown in FIG. 3, the charging circuit 30 includes a current source circuit 32, an amplifier circuit OPA, a backflow prevention circuit 34, a transistor TA, and resistors RCS and RS. The amplifier circuit OPA can also be called an operational amplifier. Note that the charging circuit 30 is not limited to the configuration shown in FIG. 3, and various modifications are possible, such as omitting some of the components or adding other components.

[0028] The current source circuit 32 outputs an output current IS based on the reference voltage. The output current IS is a current source current generated by the current source circuit 32. The output current IS is supplied to the non-inverting input terminal of the amplifier circuit OPA and to a node NCS on the drain side of the P-type transistor TA. Then, based on the output current IS, a charging current ICH is generated by the amplifier circuit OPA, the transistor TA, and resistors RS and RCS.

[0029] The source of transistor TA is connected to power supply node NIN, and the drain is connected to node NCS. Power supply node NIN is supplied with power supply voltage VCC. Resistor RCS is provided between node NCS and node NCSI. Resistor RS is provided between node NCS and node NCSR. The amplifier circuit OPA has a non-inverting input terminal connected to node NCSI, an inverting input terminal connected to node NCSR, and an output terminal connected to the gate of transistor TA. The amplifier circuit OPA is enabled when the enable signal EN is low. As a result, a charging current ICH = (RCS / RS) × IS is supplied to node NCSR, and is then supplied to node NB, the charging node, as charging current ICH.

[0030] The backflow prevention circuit 34 includes a P-type transistor TB1, an N-type transistor TB2, and a resistor RB. The source of the transistor TB1 is connected to a node NB, and the drain is connected to a node NCSR. The source of the N-type transistor TB2 is connected to the ground node, and the drain is connected to a node NB2 of the gate of the transistor TB1. The resistor RB is provided between the nodes NB and NB2.

[0031] To start charging the battery 10, the control circuit 50 turns on transistor TB2 with a control signal SDB. This also turns on transistor TB1, causing a charging current ICH to flow from node NCSR to node NB, charging the battery 10. When charging of the battery 10 is to end, the control circuit 50 turns off transistor TB2 with a control signal SDB. This also turns off transistor TB1, and the backflow prevention circuit 34 prevents a backflow of charge from the battery 10 to the charging circuit 30.

[0032] FIG. 4 is an explanatory diagram illustrating the storage of voltage interval setting information and weighting coefficients in the storage unit 60. In FIG. 4, the storage unit 60 stores divided voltages VDV1, VDV2, VDV3, ..., VDVn-1 corresponding to the boundary voltages of the voltage intervals as voltage interval setting information, where n is an integer equal to or greater than 2. The storage unit 60 also stores weighting coefficients W1, W2, W3, ..., Wn set for the voltage intervals. The voltage interval setting information and weighting coefficients are stored in, for example, a nonvolatile memory 64 and loaded from the nonvolatile memory 64 to the register unit 62 during operation of the circuit device 20. The control circuit 50 then performs processes such as integrating the weighting coefficients based on the voltage interval setting information and weighting coefficients loaded into the register unit 62 to determine the charge capacity of the battery 10.

[0033] 2. Weighting coefficient accumulation process For example, a comparative example of this embodiment uses a component such as a coulomb counter, which is an IC that measures the charge flowing into and out of a battery, to determine the battery's charge capacity. For example, this comparative example uses a coulomb counter to determine whether the battery's capacity has been fully used and update the cycle time. However, this comparative example requires components such as a coulomb counter in addition to the charging circuit device, which hinders efforts to reduce the size and cost of electronic devices.

[0034] For example, in small electronic devices such as earphones, the number of components that can be installed is limited due to the constraints of the housing, so it may not be possible to install components such as a coulomb counter that measures charge.In such cases, for small electronic devices that can be used all day on a single full charge, one method is to assume that the device is charged once a day, and when the battery voltage reaches the full charge voltage during charging, add 1 to the cycle time and update it.

[0035] Chargers for small electronic devices, which are small devices, may come with a portable charging case with a built-in battery for mobile charging. In such cases, there is a use case where the small electronic device is used for only a few hours and then stored in the charging case. However, the method of updating the cycle time when the full charge voltage is reached during charging has the problem that the full charge voltage may be reached multiple times in a day, making the cycle time update process unsuitable for practical use.

[0036] In this embodiment, multiple thresholds (division voltages) are set in advance for the voltage of a battery such as a secondary battery, and a battery capacity weighting is set for each voltage interval (voltage range) separated by the set thresholds. The battery charge capacity is then calculated based on the integrated value of the weighting coefficient, which is the weighting of the battery capacity. Furthermore, when the integrated value of the weighting coefficient reaches 1, corresponding to 100% charge capacity, during repeated battery charging, the cycle time is incremented by 1 and updated. Furthermore, when integrating the weighting coefficient, the internal resistance is measured during charging to eliminate the effect of voltage drop due to the battery's internal resistance and enable evaluation at a voltage equivalent to the battery's open-circuit voltage. Specifically, to match actual use and without using other measuring components such as a coulomb counter, the charge capacity of a charged battery is simply calculated within the circuit device (IC) of the charging device, and it is determined, for example, whether the battery capacity has been fully used. Furthermore, a simulated open-circuit voltage of the battery, which can be calculated by measuring the internal resistance of the battery and the resistance of the charging path, is used for this determination. This makes it possible to address increases in internal resistance due to battery degradation. In this way, in this embodiment, the battery charge capacity can be easily calculated and the battery capacity can be determined to be 100% used simply by using a single component of the circuit device, which is the charging device, without requiring any special charge measurement components. This makes it possible to update the cycle time to match actual use.

[0037] Next, the method of this embodiment will be described in detail with reference to FIG. 5. In FIG. 5, the range in which the battery voltage VBAT changes is divided into multiple voltage ranges VI1 to VI8. The voltage ranges VI1 to VI8 correspond, for example, to the first voltage range through the n-th voltage range. Specifically, as described with reference to FIG. 4, the voltage ranges VI1 to VI8 are set using the divided voltages VDV1 to VDV7 stored in the storage unit 60. For example, the divided voltage VDV1 is a threshold voltage that sets the boundary between the voltage range VI1 and the voltage range VI2, and the divided voltage VDV2 is a threshold voltage that sets the boundary between the voltage range VI2 and the voltage range VI3. The same applies to the other divided voltages VDV3 to VDV7. Note that, although the voltage ranges VI1 to VI8 are equally spaced in FIG. 5, they may be unequally spaced.

[0038] Weighting coefficients W1 to W8 are set for the voltage sections VI1 to VI8. That is, as explained with reference to FIG. 4, the weighting coefficients W1 to W8 stored in the memory unit 60 are set as weights for the voltage sections VI1 to VI8. These weighting coefficients are set according to the charging characteristics, which are the battery voltage-battery capacity characteristics shown in A1 of FIG. 5. For example, if a fully charged battery capacity is 1.0, which corresponds to 100%, the weighting coefficient W1 for voltage section VI1 is set to 0.0625. This means that 6.25% of the battery capacity is charged in voltage section VI1. The weighting coefficient W2 for voltage section VI2 is set to 0.125, which means that 12.5% ​​of the battery capacity is charged in voltage section VI2. The weighting coefficients for voltage sections VI3 to VI6 are set to W3 = W4 = W5 = W6 = 0.15625, which means that 15.625% of the battery capacity is charged in each of the voltage sections VI3 to VI6. The weighting coefficients for the voltage sections VI7 and VI8 are set in a similar manner.

[0039] In FIG. 5, during the first charging period TC1, the battery voltage VBAT changes from the voltage corresponding to the divided voltage VDV5 to the fully charged voltage. Therefore, in this case, a first integration process is performed to integrate the weighting coefficients W6 = 0.15625, W7 = 0.125, and W8 = 0.0625 for the voltage sections VI6, VI7, and VI8, respectively, to obtain WS (Weight SUM) as 0.15625 + 0.125 + 0.0625 = 0.34375. WS = 0.34375 indicates that the charge capacity is 34.375% of the fully charged battery capacity. The obtained WS = 0.34375 is then written and stored in, for example, the register unit 62 shown in FIG. 2. As described above, the register unit 62 is a discharge circuit that operates using the battery voltage VBAT as its power supply voltage. Therefore, even when the electronic device 2 is removed from the charging case or charging stand that has the power transmitting device 14 and is no longer receiving power from the power transmitting device 14, the register unit 62 can hold WS = 0.34375. Note that although WS can be written and held in the nonvolatile memory 64, it is preferable to write WS to the register unit 62 if the number of times the nonvolatile memory 64 can be written is limited.

[0040] Then, after the first charging period TC1, the electronic device 2, such as earphones, is removed from, for example, the charging case or charging stand, and the user uses the electronic device 2. As a result, the battery voltage VBAT drops from the fully charged voltage to a voltage within voltage interval VI2. Then, during the subsequent second charging period TC2, the battery voltage VBAT changes from a voltage within voltage interval VI2 to a voltage corresponding to the divided voltage VDV4. In this case, a first integration process is performed in which the weighting coefficient W2=0.125 for voltage interval VI2 is multiplied by 1 / 4 (0.125 / 4) and the weighting coefficients W3=0.15625 and W4=0.15625 for voltage intervals VI3 and VI4 are integrated, resulting in WS being calculated as 0.125 / 4 + 0.15625 + 0.15625 = 0.34375. A second integration process is then performed to integrate the integrated value of the weighting coefficients during the first charging period TC1, WS=0.34375, and the integrated value of the weighting coefficients during the second charging period TC2, WS=0.34375, to obtain IWS (Integral Weight SUM)=0.6875. Note that IWS during the first charging period TC1 is 0.34375. These values ​​WS=0.34375 and IWS=0.6875 are written and stored in register unit 62. Because register unit 62 is a discharge circuit that operates using battery voltage VBAT as its power supply voltage, register unit 62 can hold WS=0.34375 and IWS=0.6875 even after power reception from power transmitting device 14 is stopped.

[0041] Next, after the second charging period TC2, the electronic device 2 is removed from the charging case or charging stand, and the user uses the electronic device 2. As a result, the battery voltage VBAT drops from a voltage corresponding to the divided voltage VDV4 to a voltage corresponding to the divided voltage VDV3. Then, during the subsequent third charging period TC3, the battery voltage VBAT changes from a voltage corresponding to the divided voltage VDV3 to within the voltage interval VI7. In this case, a first integration process is performed to integrate the weighting coefficients W4 = 0.15625, W5 = 0.15625, and W6 = 0.15625 for the voltage intervals VI4, VI5, and VI6 by 0.125 / 2, which is half the weighting coefficient W7 = 0.125 for the voltage interval VI7. WS is calculated as 0.15625 + 0.15625 + 0.15625 + 0.125 / 2 = 0.53125. Then, a second integration process is performed in which IWS=0.6875 up to the second charging period TC2 is integrated with WS=0.53125 in the third charging period TC3, to obtain IWS=1.21875.

[0042] Here, ISW=1.0 corresponds to 100%, which is a full charge. Therefore, an IWS of 1.0 or greater means that the first, second, and third charging cycles have resulted in at least 100% charging, which corresponds to a full charge. Therefore, as shown in A2 of FIG. 5, the cycle time is updated by incrementing it by 1, and the updated cycle time is written to nonvolatile memory 64. Then, 0.21875 of IWS=1.21875 is set as the initial value for the integration process for the next, fourth charging period TC4. In this way, the cycle time corresponding to the number of charges can be updated, provided that the battery capacity has been charged to 100%, which corresponds to a full charge. Furthermore, by writing the cycle time to nonvolatile memory 64, the cycle time information can be retained even if, for example, battery 10 is completely discharged.

[0043] For example, a comparative example of this embodiment involves providing a component for measuring charge, such as a coulomb counter, between the circuit device 20 and the battery 10, but this increases the number of components, hindering efforts to reduce the size and cost of the electronic device 2. In contrast, this embodiment uses weighting coefficients stored in the storage unit 60 to determine the charge capacity, eliminating the need for a component for measuring charge, such as a coulomb counter, and enabling the electronic device 2 to be reduced in size and cost.

[0044] Another method is to measure the charging time and charging current value in each voltage interval and calculate the product of the measured charging time and charging current value to determine the charge capacity of the battery 10. However, this method requires measuring the charging time and charging current and calculating their product, which increases the processing load on the circuit device 20. In contrast, in this embodiment, weighting coefficients corresponding to the battery capacity in each voltage interval are stored in the storage unit 60, and the charge capacity of the battery 10 is calculated by integrating these weighting coefficients, which makes it possible to reduce the processing load on the circuit device 20 and achieve low power consumption.

[0045] Furthermore, assuming that charging occurs once a day, a method of updating the cycle time by +1 when the battery voltage VBAT reaches the full charge voltage during charging would not be able to determine an accurate cycle time in a use case such as that shown in Fig. 5. In contrast, in this embodiment, as shown in Fig. 5, the cycle time is updated when the integrated value of the weighting coefficient for the battery capacity becomes 1 or greater, making it possible to measure the cycle time accurately.

[0046] FIG. 6 is a flowchart illustrating the operation of this embodiment. When the electronic device 2 is attached to a charging case or charging stand and charging of the battery 10 begins, the voltage measurement circuit 40 measures the battery voltage VBAT (steps S1 and S2). For example, the A / D conversion circuit 42 of the voltage measurement circuit 40 performs A / D conversion of the battery voltage VBAT and outputs digital data of the battery voltage VBAT to the control circuit 50. The control circuit 50 then reads weighting coefficients from the storage unit 60 based on the measurement result of the battery voltage VBAT (digital data of VBAT) and performs an integration process for the weighting coefficients (step S3). Taking FIG. 5 as an example, during the first charging period TC1, the weighting coefficients W6, W7, and W8 for the voltage sections VI6, VI7, and VI8 are read, and an integration process for the weighting coefficients W6, W7, and W8 is performed. During the second charging period TC2, the weighting factors W2, W3, and W4 for the voltage sections VI2, VI3, and VI4 are read out, and an integration process is performed for the weighting factors W2, W3, and W4. The same is true for the third and fourth charging periods TC3 and TC4. Note that the integration process for the weighting factors may include not only a first integration process for the weighting factors for each charging period, but also a second integration process for the weighting factors for multiple charging periods.

[0047] The control circuit 50 then determines the charge capacity of the battery 10 charged by the charging circuit 30 based on the result of the integration process for the weighting coefficients (step S4). In this case, the cycle time may be updated based on the determined charge capacity as described in Fig. 5, or the charge capacity of the battery 10 may be displayed on the display unit of the electronic device 2, or a notification process may be performed such as by sound or the like. It is then determined whether charging has finished (step S5). If not finished, the process returns to step S2, and if finished, the process ends.

[0048] As described above, the circuit device 20 of this embodiment includes a charging circuit 30 that charges the battery 10, a voltage measurement circuit 40 that measures the battery voltage VBAT, and a storage unit 60 that stores weighting coefficients for battery capacity in each of a plurality of voltage sections. For example, the charging circuit 30 shown in FIGS. 1 and 2 charges the battery 10, and the voltage measurement circuit 40 measures the battery voltage VBAT at the node NB connected to the battery 10 and outputs the measurement results to the control circuit 50. As described with reference to FIG. 4, the storage unit 60 stores weighting coefficients for battery capacity associated with each voltage section. The circuit device 20 also includes a control circuit 50 that performs an integration process for the weighting coefficients based on the measurement results of the battery voltage VBAT by the voltage measurement circuit 40 and determines the charge capacity of the battery 10 charged by the charging circuit 30 based on the results of the integration process. For example, as described with reference to FIG. 5, the control circuit 50 reads from the storage unit 60 the weighting coefficients for the voltage sections to which the battery voltage VBAT, which changes during the charging period, belongs. The weighting coefficients thus read are then integrated to determine, for example, the charge capacity of the battery 10 charged during the charging period.

[0049] In this way, it is possible to determine the charge capacity of the battery 10 charged by the charging circuit 30 by integrating the weighting coefficients stored in the storage unit 60, without providing a charge measurement component external to the circuit device 20. Furthermore, it is not necessary to perform processing such as measuring the charging time and charging current and calculating the product of the charging time and charging current, and it is possible to determine the charge capacity through light-load processing by reading and integrating the weighting coefficients from the storage unit 60. Furthermore, by storing weighting coefficients according to the charging characteristics of the battery 10 in the storage unit 60, it is possible to more accurately determine the charge capacity through low-load processing.

[0050] Furthermore, as an integration process for weighting coefficients, control circuit 50 performs a first integration process that integrates weighting coefficients for voltage sections during the charging period. Taking Fig. 5 as an example, as the first integration process, during charging period TC1, integration process of weighting coefficients W6, W7, and W8 for voltage sections VI6, VI7, and VI8 is performed, and during charging period TC2, integration process of weighting coefficients W2, W3, and W4 for voltage sections VI2, VI3, and VI4 is performed. Furthermore, during charging period TC3, integration process of weighting coefficients W4, W5, W6, and W7 for voltage sections VI4, VI5, VI6, and VI7 is performed.

[0051] In this way, for example, by performing an integration process of the weighting coefficients of the voltage section to which the battery voltage VBAT, which changes during the charging period, belongs, it becomes possible to determine the charge capacity of the battery 10 charged during the charging period using a low-load process.

[0052] The voltage intervals are the first to n-th voltage intervals obtained by dividing the range in which the battery voltage VBAT changes. Here, n is an integer equal to or greater than 2. Taking FIG. 5 as an example, the first to n-th voltage intervals are voltage intervals VI1 to VI8. Note that the number of voltage intervals is not limited to eight as in FIG. 5 and can be any number. Assume that the battery voltage VBAT when charging starts belongs to the ith voltage interval of the first to n-th voltage intervals, and the battery voltage VBAT when charging ends belongs to the j-th voltage interval of the first to n-th voltage intervals. Here, i is an integer satisfying 1≦i≦n−1, and j is an integer satisfying i≦j≦n. In this case, the control circuit 50 performs the first integration process using weighting coefficients for the ith to j-th voltage intervals. 5 as an example, in charging period TC1, the i-th voltage interval is voltage interval VI6 and the j-th voltage interval is voltage interval VI8, so a first integration process is performed using weighting coefficients W6 to W8 for voltage intervals VI6 to VI8. In charging period TC2, the i-th voltage interval is voltage interval VI2 and the j-th voltage interval is voltage interval VI4, so a first integration process is performed using weighting coefficients W2 to W4 for voltage intervals VI2 to VI4. In charging period TC3, the i-th voltage interval is voltage interval VI4 and the j-th voltage interval is voltage interval VI7, so a first integration process is performed using weighting coefficients W4 to W7 for voltage intervals VI4 to VI7.

[0053] In this way, when the battery voltage VBAT changes from the voltage in the ith voltage interval at the start of charging to the voltage in the jth voltage interval at the end of charging due to charging of the battery 10 during the charging period, the charge capacity of the battery 10 during that charging period can be determined by performing the first integration process using the weighting coefficients from the ith voltage interval to the jth voltage interval. Therefore, the charge capacity of the battery 10 during that charging period can be determined by the simple process of measuring the battery voltage VBAT from the start of charging to the end of charging during the charging period, reading out the weighting coefficients for the corresponding ith voltage interval to the jth voltage interval, and performing integration processing.

[0054] If the battery voltage VBAT is within a voltage interval, a first integration process may be performed in which the weighting coefficient for the voltage interval is multiplied by an interpolation coefficient corresponding to the voltage ratio of the battery voltage VBAT within the voltage interval. Taking Fig. 5 as an example, during charging period TC2, the weighting coefficient W2 for voltage interval VI2 is multiplied by 1 / 4, which is the interpolation coefficient corresponding to the voltage ratio of the battery voltage VBAT within voltage interval VI2. During charging period TC3, the weighting coefficient W7 for voltage interval VI7 is multiplied by 1 / 2, which is the interpolation coefficient corresponding to the voltage ratio of the battery voltage VBAT within voltage interval VI7.

[0055] Furthermore, the control circuit 50 performs a second integration process as an integration process for the weighting coefficient, integrating the results of the first integration process for each of the multiple charging periods. Taking Fig. 5 as an example, the control circuit 50 performs a second integration process to obtain IWS = 0.6875 by integrating the result of the first integration process for the first charging period TC1, WS = 0.34375, by the result of the first integration process for the second charging period TC2, WS = 0.34375. The control circuit 50 also performs a second integration process to obtain IWS = 1.21875 by integrating the result of the first integration process for the third charging period TC3, WS = 0.53125, by IWS = 0.6875.

[0056] In this way, when charging is performed multiple times, an integrated value obtained by integrating the results of the first integration process over multiple charging periods can be obtained by the second integration process. This makes it possible to obtain the total charge capacity of the battery 10 charged over multiple charging periods. This has the advantage that such total charge capacity can be obtained by a light-load process of integrating the results of the first integration process.

[0057] Furthermore, the control circuit 50 performs an update process for the cycle time of the battery 10 based on the result of the second integration process. Taking Fig. 5 as an example, the second integration process, which integrates the results of the first integration processes over multiple charging periods TC1 to TC3, determines IWS = 1.21875. In this case, based on the result of the second integration process, IWS = 1.21875, an update process is performed to add 1 to the cycle time, as shown at A2.

[0058] In this way, the cycle time is updated using an integrated value obtained by integrating the results of the first integration process over multiple charging periods. This makes it possible to update the cycle time using the total charge capacity of the battery 10 charged over multiple charging periods. This has the advantage that the cycle time can be updated using a light-load process that uses an integrated value obtained by integrating the results of the first integration process.

[0059] Furthermore, when the battery voltage VBAT at the end of charging belongs to the jth voltage section among the first to nth voltage sections, the control circuit 50 may perform integration processing using the weighting coefficients for the first to jth voltage sections. Here, j is an integer satisfying 1≦j≦n. Taking FIG. 5 as an example, if the battery voltage at the end of charging during the first charging period TC1 belongs to voltage section VI8 (the jth voltage section), integration processing is performed using the weighting coefficients W1 to W8 for the voltage sections VI1 to VI8 (the first to jth voltage sections). In this way, the charge capacity of the battery 10 at the end of charging during the charging period TC1 can be determined, and the charge capacity (remaining charge) can be displayed on the display unit of the electronic device 2, for example. Similarly, if the battery voltage at the end of charging during the second charging period TC2 belongs to voltage section VI4, integration processing is performed using the weighting coefficients W1 to W4 for the voltage sections VI1 to VI4. Furthermore, in the third charging period TC3, if the battery voltage at the end of charging belongs to voltage section VI7, the weighting coefficients W1 to W7 for the voltage sections VI1 to VI7 are integrated.

[0060] In this way, it is possible to determine the charge capacity of the battery 10 at the end of charging by measuring the battery voltage VBAT when charging is completed, reading out the weighting coefficients for the first voltage section to the jth voltage section from the storage unit 60, and performing an integration process. Then, by performing a notification process such as a display process on the display unit based on the determined charge capacity, it is possible to determine the charge capacity through a light-load process of reading out and integrating the weighting coefficients, and to notify the determined charge capacity to the user, etc.

[0061] The storage unit 60 also stores information for setting multiple voltage intervals and information on weighting coefficients for each voltage interval. Taking FIG. 4 as an example, the storage unit 60 stores divided voltages VDV1 to VDVn-1, which are boundary voltages between voltage intervals, as information for setting the voltage intervals. The boundary voltage between voltage intervals is a voltage that indicates the boundary between adjacent voltage intervals, such as the upper or lower limit voltage of a voltage interval. However, the information for setting the voltage intervals is not limited to such divided voltages, and various information can be used as long as it is information that can identify the voltage interval to which the battery voltage VBAT belongs.

[0062] In this way, it is possible to determine the voltage interval to which the measured battery voltage VBAT belongs based on the voltage interval setting information read from the storage unit 60, and to read the weighting coefficient for that voltage interval from the storage unit 60. Then, by performing an integration process on the read weighting coefficients, it is possible to determine the charge capacity of the battery 10 charged by the charging circuit 30 with a process that imposes a light processing load.

[0063] The weighting coefficient is information indicating, for example, the ratio of the battery capacity charged in each voltage section to the battery capacity when fully charged. Taking Fig. 5 as an example, the weighting coefficient W1 for voltage section VI1 is 0.0625 (6.25%), which is the ratio of the battery capacity charged in voltage section VI1 to 1.0 (100%), which corresponds to the battery capacity when fully charged. Similarly, the weighting coefficient W2 for voltage section VI2 is 0.125 (12.5%), which is the ratio of the battery capacity charged in voltage section VI2 to 1.0 (100%), which corresponds to the battery capacity when fully charged. The same applies to the weighting coefficients W3 to W8 for voltage sections VI3 to VI8.

[0064] In this way, by integrating the weighting coefficients, it becomes possible to determine the percentage of the battery capacity that has been charged relative to the fully charged battery capacity. This has the advantage that the charged battery capacity can be determined by a light-load process of reading the weighting coefficients from the storage unit 60 and performing the integration process.

[0065] 3. Measurement of internal resistance In this embodiment, the battery voltage VBAT is measured and the weighting coefficients are calculated based on the measurement results. However, if the battery voltage VBAT is used directly to determine whether the voltage range VI1 to VI8 defined by the divided voltages VDV1 to VDV7 in Fig. 5 is included, there is a risk of errors occurring in the measurement.

[0066] For example, Figure 7 is an explanatory diagram of the internal resistance RCL and open-circuit voltage VCL of the battery 10. When the battery 10 is being charged by the charging current ICH from the circuit device 20, the battery voltage is expressed as VBAT = VCL + ICH × RCL due to the voltage drop across the internal resistance RCL. Therefore, if the measurement result of the battery voltage VBAT shown in B1 of Figure 7 is used as is, there is a risk of a measurement discrepancy of ICH × RCL with respect to the open-circuit voltage VCL of the battery 10. Furthermore, the internal resistance RCL tends to increase as the battery 10 deteriorates, which also contributes to a wider measurement discrepancy.

[0067] Therefore, in this embodiment, the internal resistance RCL of the battery 10 is measured while the circuit device 20 is charging the battery 10. Then, based on the measured internal resistance RCL, the open-circuit voltage VCL of the battery 10 is calculated using the relational expression VCL = VBAT - ICH × RCL. In this way, instead of the battery voltage VBAT shown in B1 of FIG. 8, the open-circuit voltage VCL obtained by lowering the battery voltage VBAT by ICH × RCL is used to determine the voltage range and perform the integration process of the weighting coefficient. Therefore, it is possible to calculate the charge capacity of the battery 10 using more accurate voltage measurement results. It is also possible to deal with increases in the internal resistance RCL due to deterioration of the battery 10.

[0068] FIG. 9 is an explanatory diagram of a method for measuring internal resistance RCL. For example, in this embodiment, during constant-current charging in CCCV charging, the charging current is increased in steps up to a target current value ITG. Then, as the charging current is increased in steps, the internal resistance RCL is measured. Specifically, the charging current is set to I0, and the battery voltage VBAT=V0 when the charging current is I0 is measured. Then, the charging current is increased in steps from I0, and the battery voltage VBAT=VN when the charging current is IN is measured. Then, when the relationship IN-I0>IDF holds with respect to the preset IDF, RCL=(ΔV / ΔI)=(VN-V0) / (IN-I0) is calculated. IDF is preferably set to a value according to the resolution of the A / D conversion circuit 42, which A / D converts VN and V0; for example, approximately 1 mA. The above process of setting I0 and calculating RCL is repeated until the charging current reaches the target current value ITG, updating the value of the internal resistance RCL. The finally obtained internal resistance RCL is used to calculate the open circuit voltage VCL.

[0069] Fig. 10 is a flowchart explaining the detailed operation of this embodiment. First, when charging begins, for example, by placing the electronic device 2 on the charging stand, the charging current begins to step up (steps S11 and S12). For example, when charging the battery 10 using power received contactlessly as shown in Fig. 2, if constant current charging at a target current value is started without stepping up the charging current, appropriate charging will not be possible due to a drop in the power supply voltage VCC, etc. For this reason, in this embodiment, constant current charging is performed after stepping up the charging current value to the target current value ITG.

[0070] Next, as described with reference to FIG. 9, the set I0, IN, and IDF are used to determine whether the relationship IN-I0>IDF holds (step S13). If IN-I0>IDF holds, the internal resistance RCL is calculated using the relationship RCL=(VN-V0) / (IN-I0) (step S14). The calculated value of internal resistance RCL is stored, for example, in register unit 62. Then, it is determined whether the charging current IN has reached the target current value ITG. If it has not, the process returns to step S13 and repeats the processes of steps S13 and S14. In this way, the value of internal resistance RCL stored in register unit 62 is updated until the charging current reaches the target current value ITG, making it possible to obtain the internal resistance RCL when the charging current reaches the target current value ITG.

[0071] When the charging current reaches the target current value ITG, the battery voltage VBAT is measured, and the open-circuit voltage VCL is calculated from the relational expression VCL = VBAT - ICH × RCL (step S16). When the open-circuit voltage VCL crosses a voltage section, the weighting coefficient for that voltage section is integrated, and the result of the integration process is stored in the register unit 62 (steps S17 and S18). Next, it is determined whether the electronic device 2 has been removed from the charging base. If not, it is determined whether IWS, which is the integrated value of the weighting coefficients during the charging period, exceeds 1 (steps S19 and S20). If IWS exceeds 1, the cycle time is updated by +1 as described in A2 of FIG. 5, and stored in the nonvolatile memory 64 (step S21), and the process returns to step S16. If IWS does not exceed 1, the cycle time is not updated and the process returns to step S16. On the other hand, if it is determined in step S19 that the electronic device 2 has been removed from the charging stand, it is determined whether the electronic device 2 has been placed on the charging stand (step S22), and if it has been placed on the charging stand, the process returns to step S11 and charging begins.

[0072] As described above, in this embodiment, the control circuit 50 calculates the internal resistance RCL of the battery 10 based on the battery voltage VBAT=V0 measured when the charging current value of the charging circuit 30 is the first current value I0 and the battery voltage VBAT=VN measured when the charging current value is the second current value IN. The control circuit 50 then corrects the battery voltage VBAT based on the calculated internal resistance RCL and the charging current value of the charging circuit 30 to calculate the open-circuit voltage VCL of the battery 10. For example, the control circuit 50 calculates the open-circuit voltage VCL by correcting the battery voltage VBAT using the relational expression VCL=VBAT-ICH×RCL. The control circuit 50 then performs integration processing on the weighting coefficient for the voltage section to which the open-circuit voltage VCL belongs. That is, the open-circuit voltage VCL, which is the battery voltage VBAT when the battery 10 is in an open-circuit state, is used to calculate the weighting coefficient described with reference to FIGS. 1 to 6.

[0073] In this way, it is possible to measure the internal resistance RCL of the battery 10 and the resistance in the charging path, and use a weighting coefficient based on the simulated open-circuit voltage VCL of the battery 10 to determine the charge capacity of the battery 10. This allows for more accurate measurement of the charge capacity and cycle time. It also makes it possible to address issues such as an increase in the internal resistance RCL due to deterioration of the battery 10.

[0074] Furthermore, when changing the charging current value up to the target current value ITG for constant current charging, the control circuit 50 sets the charging current value along the way to the target current value ITG to the first current value I0 and the second current value IN. For example, when stepping up the charging current value to the target current value ITG as shown in Fig. 9, the control circuit 50 sets the charging current value along the way to the first current value I0 and the second current value IN. Then, the control circuit 50 calculates the internal resistance RCL of the battery 10 based on the first current value I0 and the second current value IN and the battery voltages V0 and VN measured when the charging current value is the first current value I0 and the second current value IN.

[0075] In this way, in charge control in which constant current charging is performed after changing the charging current value to the target current value ITG, it is possible to calculate internal resistance RCL using the first current value I0 and the second current value IN, which are charging current values ​​along the way to the target current value ITG. For example, if the battery voltage VBAT is V0 when the charging current value is the first current value I0 and the battery voltage VBAT is VN when the charging current value is the second current value IN, internal resistance RCL can be calculated using the relational expression RCL = (VN - V0) / (IN - I0). Then, by performing constant current charging after the charging current value has changed to the target current value ITG, appropriate charge control becomes possible, for example, when charging battery 10 using power received contactlessly.

[0076] Furthermore, the control circuit 50 repeatedly calculates and updates the internal resistance RCL until the charging current value reaches the target current value ITG. For example, as shown in steps S13, S14, and S15 of Fig. 10, when IN - I0 > IDF, the process of calculating the internal resistance RCL using the relational expression RCL = (VN - V0) / (IN - I0) is repeated until the charging current value IN reaches the target current value ITG, and the value of the internal resistance RCL stored in the register unit 62 is updated. The value of the internal resistance RCL when the charging current value reaches the target current value ITG is then set as the final internal resistance value, and the open-circuit voltage VCL is calculated based on this RCL.

[0077] In this way, the value of internal resistance RCL calculated from the first current value I0 and the second current value IN when the charging current value reaches the target current value ITG for constant current charging can be used as the internal resistance value for calculating the open-circuit voltage VCL. Therefore, when a constant current of the target current value ITG is applied during constant current charging, the charge capacity of the battery 10 can be calculated by integrating a weighting coefficient based on an appropriate open-circuit voltage VCL calculated using that constant current value. This allows for more accurate measurement of the charge capacity and cycle time.

[0078] As described above, the circuit device of this embodiment includes a charging circuit that charges the battery, a voltage measurement circuit that measures the battery voltage, and a memory unit that stores weighting coefficients for battery capacity in each of a plurality of voltage intervals. The circuit device also includes a control circuit that performs an integration process for the weighting coefficients based on the battery voltage measurement results by the voltage measurement circuit, and determines the charge capacity of the battery charged by the charging circuit based on the results of the integration process.

[0079] According to this embodiment, a battery is charged by a charging circuit, and the battery voltage is measured by a voltage measurement circuit. A memory unit stores weighting coefficients for battery capacity in each voltage range, and a control circuit performs an integration process for the weighting coefficients based on the battery voltage measurement results, and calculates the battery charge capacity based on the results of the integration process. In this manner, the charge capacity of a battery charged by a charging circuit can be calculated by integrating the weighting coefficients stored in the memory unit, without the need for an external charge measurement component. Storing weighting coefficients for the charging characteristics in the memory unit also makes it possible to calculate the charge capacity with a lighter load.

[0080] In this embodiment, the control circuit may perform, as the integration process, a first integration process that integrates weighting coefficients for voltage sections in a charging period.

[0081] In this way, by performing an integration process of the weighting coefficients of the voltage section to which the battery voltage belongs, it becomes possible to determine the charge capacity of the battery charged during the charging period with a low-load process.

[0082] In this embodiment, the plurality of voltage intervals may be first to n-th voltage intervals obtained by dividing the battery voltage change interval. When the battery voltage at the start of charging belongs to the ith voltage interval among the first to n-th voltage intervals and the battery voltage at the end of charging belongs to the jth voltage interval among the first to n-th voltage intervals, the control circuit may perform the first integration process using weighting coefficients for the ith to j-th voltage intervals, where n is an integer equal to or greater than 2, i is an integer satisfying 1≦i≦n−1, and j is an integer satisfying i≦j≦n.

[0083] In this way, when the battery voltage changes from the voltage in the i-th voltage interval at the start of charging to the voltage in the j-th voltage interval at the end of charging due to charging of the battery during the charging period, it is possible to determine the charge capacity of the battery during that charging period by performing a first integration process using weighting coefficients from the i-th voltage interval to the j-th voltage interval.

[0084] In this embodiment, the control circuit may perform, as the integration process, a second integration process that integrates the results of the first integration process in each of the multiple charging periods.

[0085] In this way, when charging is performed multiple times, it becomes possible to obtain an integrated value obtained by integrating the results of the first integration process over multiple charging periods by the second integration process.

[0086] The control circuit may also perform a process of updating the cycle time of the battery based on the result of the second integration process.

[0087] In this way, the cycle time is updated using an integrated value obtained by integrating the results of the first integration process over multiple charging periods, and the cycle time can be updated using the total charge capacity of the battery charged over multiple charging periods.

[0088] In this embodiment, the plurality of voltage sections may be first to n-th voltage sections obtained by dividing the battery voltage change section. When the battery voltage at the time of charging completion belongs to the j-th voltage section among the first to n-th voltage sections, the control circuit may perform integration processing using weighting coefficients for the first to j-th voltage sections, where n is an integer equal to or greater than 2 and j is an integer satisfying the relationship 1≦j≦n.

[0089] In this way, the battery voltage when charging is completed is measured, and the weighting coefficients for the first voltage section to the jth voltage section are read from the memory unit and integrated to determine the charge capacity of the battery when charging is completed.

[0090] The storage unit may also store information for setting a plurality of voltage intervals and information on weighting coefficients for each voltage interval.

[0091] In this way, it is possible to determine the voltage range to which the measured battery voltage belongs based on the voltage range setting information read out from the memory unit, and to read out the weighting coefficient for that voltage range from the memory unit.

[0092] The weighting coefficient may also be information indicating the ratio of the battery capacity charged in each voltage section to the battery capacity when fully charged.

[0093] In this way, by carrying out the integration process of the weighting coefficients, it becomes possible to determine the percentage of the battery capacity that has been charged relative to the fully charged battery capacity.

[0094] The control circuit may also determine the internal resistance of the battery based on the battery voltage measured by the voltage measurement circuit when the charging current value of the charging circuit is a first current value and the battery voltage measured by the voltage measurement circuit when the charging current value is a second current value.The control circuit may then correct the battery voltage based on the internal resistance and the charging current value of the charging circuit to determine the open-circuit voltage of the battery, and perform integration processing using a weighting coefficient for the voltage section to which the open-circuit voltage belongs.

[0095] In this way, it becomes possible to measure the internal resistance of the battery and use a weighting coefficient based on the open voltage of the battery to determine the charge capacity of the battery.

[0096] Furthermore, when changing the charging current value to the target current value for constant current charging, the control circuit may set the charging current value to the first current value and the second current value midway through the change to the target current value.

[0097] In this way, in charging control in which the charging current value is changed to a target current value and then constant current charging is performed, it is possible to determine the internal resistance using the first current value and the second current value, which are the charging current values ​​during the change to the target current value.

[0098] The control circuit may also repeatedly determine and update the internal resistance until the charging current value reaches the target current value.

[0099] In this way, the internal resistance value calculated from the first current value and the second current value when the charging current value reaches the target current value for constant current charging can be used as the internal resistance value for calculating the open voltage.

[0100] The electronic device of this embodiment includes the circuit device and a battery.

[0101] Although the present embodiment has been described in detail above, those skilled in the art will readily understand that many modifications are possible without substantially departing from the novel features and advantages of the present disclosure. Therefore, all such modifications are intended to be included within the scope of the present disclosure. For example, a term described at least once in the specification or drawings together with a different term having a broader or equivalent meaning may be replaced with that different term anywhere in the specification or drawings. Furthermore, all combinations of the present embodiment and modifications are also included within the scope of the present disclosure. Furthermore, the configurations and operations of the circuit devices and electronic devices are not limited to those described in the present embodiment, and various modifications are possible. [Explanation of symbols]

[0102] 2...electronic device, 10...battery, 12...device to be powered, 14...power transmission device, 20...circuit device, 30...charging circuit, 32...current source circuit, 34...backflow prevention circuit, 40...voltage measurement circuit, 42...A / D conversion circuit, 50...control circuit, 60...storage unit, 62...register unit, 64...non-volatile memory, 70...power receiving circuit, 72...rectifier circuit, 80...power supply circuit, I0...first current value, ICH...charging current, IN...second current value, ITG...target current value, L1...primary coil, L2...secondary coil, OPA...amplifier circuit, RB, RS, RCS...resistance, RCL...internal resistance, TA, TB1, TB2...transistor, TBAT...terminal, TC1~TC4...charging period, VBAT...battery voltage, VCC...power supply voltage, VCL...open voltage, VDV1~VDV7...division voltage, VI1~VI8...voltage section, W1~W8...weighting coefficient

Claims

1. a charging circuit for charging the battery; a voltage measurement circuit for measuring a battery voltage of the battery; a storage unit that stores a weighting coefficient for battery capacity in each of a plurality of voltage sections; a control circuit that performs an integration process for the weighting coefficient based on the measurement result of the battery voltage by the voltage measurement circuit, and determines the charge capacity of the battery charged by the charging circuit based on the result of the integration process; A circuit device comprising:

2. 2. The circuit device according to claim 1, The control circuit The circuit device is characterized in that, as the integration process, a first integration process is performed in which the weighting coefficients of the voltage sections in the charging period are integrated.

3. 3. The circuit device according to claim 2, The plurality of voltage sections are a first voltage section to an n-th voltage section (n is an integer of 2 or more) obtained by dividing the change section of the battery voltage, The control circuit a circuit device characterized in that, when the battery voltage when the charging is started belongs to the ith voltage interval (i is an integer such that 1≦i≦n-1) of the first voltage interval to the nth voltage interval, and when the battery voltage when the charging is completed belongs to the jth voltage interval (j is an integer such that i≦j≦n) of the first voltage interval to the nth voltage interval, the first integration process is performed using the weighting coefficients of the ith voltage interval to the jth voltage interval.

4. 3. The circuit device according to claim 2, The control circuit The circuit device is characterized in that, as the integration process, a second integration process is performed in which the results of the first integration process in each charging period of a plurality of charging periods are integrated.

5. 5. The circuit device according to claim 4, The control circuit A circuit device characterized in that an update process of the cycle time of the battery is performed based on the result of the second integration process.

6. 2. The circuit device according to claim 1, The plurality of voltage sections are a first voltage section to an n-th voltage section (n is an integer of 2 or more) obtained by dividing the change section of the battery voltage, The control circuit When the battery voltage when the charging is completed falls within a jth voltage interval (j is an integer satisfying 1≦j≦n) among the first voltage interval to the nth voltage interval, the circuit device performs the integration process using the weighting coefficients of the first voltage interval to the jth voltage interval.

7. 2. The circuit device according to claim 1, The storage unit A circuit device characterized in that it stores information for setting the plurality of voltage intervals and information on the weighting coefficients for each of the voltage intervals.

8. 2. The circuit device according to claim 1, The circuit device is characterized in that the weighting coefficient is information indicating a ratio of the battery capacity charged in each of the voltage sections to the battery capacity when fully charged.

9. 2. The circuit device according to claim 1, The control circuit determining an internal resistance of the battery based on the battery voltage measured by the voltage measurement circuit when the charging current value of the charging circuit is a first current value and the battery voltage measured by the voltage measurement circuit when the charging current value is a second current value; correcting the battery voltage based on the internal resistance and the charging current value of the charging circuit to determine the open-circuit voltage of the battery; A circuit device characterized in that the integration process is performed using the weighting coefficient for the voltage section to which the open voltage belongs.

10. 10. The circuit device according to claim 9, The control circuit A circuit device characterized in that, when the charging current value is changed to a target current value for constant current charging, the charging current value is set to the first current value and the second current value during the change to the target current value.

11. 11. The circuit arrangement according to claim 10, The control circuit The circuit device is characterized in that the internal resistance is repeatedly calculated and updated until the charging current value reaches the target current value.

12. A circuit arrangement according to any one of claims 1 to 11; the battery; 1. An electronic device comprising:

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