Circuit device and electronic apparatus

Abstract

To provide a circuit device or the like for achieving proper constant current charging of a battery provided with a protection circuit.SOLUTION: The circuit device 20 includes a charging circuit 30 that charges the battery 10, and a control circuit 50 that controls the charging circuit 30. The battery 10 is provided with a protection circuit 12 of the battery 10 which is shut down when the battery 10 is in an over-discharge state. When the shutdown state of the protection circuit 12 is released, the control circuit 50 causes the charging circuit 30 to start constant current charging of the battery 10 by increasing the charging current from an initial current value that is greater than zero.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] Electronic devices capable of charging batteries may be equipped with a protection circuit called a PCM (Protection Circuit Module) on the battery side. This protection circuit prevents the battery from overcharging or overdischarging. Patent Document 1 also discloses a charge control device that prevents battery degradation due to a sudden current at the start of charging. This charge control device sets a target current value for constant current charging and performs charge control to increase the charging current to the target current value at the start of charging. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-60757 Summary of the Invention [Problem to be solved by the invention]

[0004] In electronic devices equipped with the above-mentioned protection circuit, it has been discovered that if charging control is performed to increase the charging current to a target current value after the shutdown state of the protection circuit is released, the protection circuit will enter the shutdown state again. If this situation occurs, the shutdown state of the protection circuit cannot be released, and the battery cannot be properly charged. [Means for solving the problem]

[0005] One aspect of the present disclosure relates to a circuit device that includes a charging circuit that charges a battery and a control circuit that controls the charging circuit, wherein the battery is provided with a protection circuit that shuts down when the battery is in an over-discharged state, and the control circuit causes the charging circuit to increase the charging current from an initial current value greater than zero and start constant current charging of the battery when the shutdown state of the protection circuit is released.

[0006] Another aspect of the present disclosure relates to an electronic device including the circuit device described above, the battery, and the protection circuit. [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] 10 shows a detailed configuration example of a circuit device and electronic equipment for contactless power supply. [Figure 4] An example of a charging circuit configuration. [Figure 5] An explanatory diagram of CCCV charging. [Figure 6] An illustration of step-up current charging. [Figure 7] FIG. [Figure 8] FIG. [Figure 9] FIG. 6 is an explanatory diagram illustrating storage of an initial current value, a step-up current value, and a step-up time in a storage unit. [Figure 10] 4 is a flowchart illustrating the 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 an electronic device 2 according to this embodiment. The circuit device 20 includes a charging circuit 30 and a control circuit 50. The electronic device 2 includes the circuit device 20, a battery 10, and a protection circuit 12. The circuit device 20, the electronic device 2, and the protection circuit 12 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 terminals TBAT and TVSS of the circuit device 20 via a protection circuit 12. The terminals TBAT and TVSS are external connection terminals, such as pads or packages, 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 via electrical signals. The electrical connection may also be a connection via a passive element, etc.

[0012] The protection circuit 12 is a circuit that protects the battery 10. For example, the protection circuit 12 is a circuit that detects an over-discharge state or an over-charge state of the battery 10 and protects the battery 10 from over-discharge or over-charge. The protection circuit 12 is also called, for example, a PCM (Protection Circuit Module). For example, the battery 10 and the protection circuit 12 are built into a battery pack. The terminal TVP is, for example, an external connection terminal on the positive side of the battery pack and is connected to the positive terminal of the battery 10. The terminal TVM is, for example, an external connection terminal on the negative side of the battery pack and is connected to the negative terminal of the battery 10. This terminal TVM is connected to, for example, a VSS terminal TVSS of the circuit device 20.

[0013] The protection circuit 12 (protection circuit module) includes a protection control circuit 13 and switches SW1 and SW2. The protection control circuit 13 can be realized, for example, by a battery protection IC. The switches SW1 and SW2 can be realized, for example, by N-type MOS transistors. The switches SW1 and SW2 are controlled to be turned on and off by control signals SC1 and SC2 from the protection control circuit 13.

[0014] Switches SW1 and SW2 are connected in series between node NC2, which is the negative terminal of battery 10, and node NC4, which is the terminal TVM. Node NC1 is the node for the positive terminal of battery 10. Switch SW1 is an overdischarge switch, and switch SW2 is an overcharge switch. For example, in FIG. 1, switch SW1 for overdischarge is connected between node NC2, which is the negative terminal of battery 10, and node NC3, which is the connection node between switches SW1 and SW2. Switch SW2 for overcharge is connected between node NC3 and node NC4, which is the terminal TVM.

[0015] Specifically, the transistor constituting switch SW1 has a source connected to node NC2, which is the negative terminal of battery 10, a drain connected to node NC3, and a gate to which a control signal SC1 from protection control circuit 13 is input. The transistor constituting switch SW2 has a source connected to node NC4 of terminal TVM, a drain connected to node NC3, and a gate to which a control signal SC2 from protection control circuit 13 is input. Diodes DI1 and DI2 are implemented, for example, by the body diodes of the transistors constituting switches SW1 and SW2. For example, by connecting the source and backgate of the transistor constituting switch SW1 at node NC2, diode DI1 is implemented, with its forward direction being from node NC2 to node NC3. By connecting the source and backgate of the transistor constituting switch SW2 at node NC4, diode DI2 is implemented, with its forward direction being from node NC4 to node NC3. Note that modifications are also possible, such as providing diodes DI1 and DI2 separately from switches SW1 and SW2.

[0016] For example, under normal conditions, switches SW1 and SW2 are on. When the protection control circuit 13 detects an over-discharge state, switch SW1 is turned off by control signal SC1. At this time, switch SW2 remains on. Diode DI1 is a diode whose forward direction is from node NC2 to node NC3. Therefore, when switch SW1 is turned off, the discharge current from node NC3 to node NC2 stops flowing, preventing the battery 10 from further discharging from its over-discharge state. Even when an over-discharge state is detected and switch SW1 is turned off, the charge current from node NC2 to node NC3 can flow through diode DI1. This allows the battery 10 to be charged even when it is in an over-discharge state. Note that VF is the forward voltage of the diode.

[0017] Furthermore, when the protection control circuit 13 detects an overcharge state, the control signal SC2 turns off the switch SW2. At this time, the switch SW1 remains on. The overcharge diode DI2 is a diode whose forward direction is from node NC4 to node NC3. Therefore, when the switch SW2 is turned off, the charging current from node NC3 to node NC4 stops flowing, thereby preventing the battery 10 from being overcharged and further charged. Even when the overcharge state is detected and the switch SW2 is turned off, the discharging current from node NC4 to node NC3 can flow via the diode DI2. This allows the battery 10 to be discharged from the overcharge state.

[0018] The charging circuit 30 charges the battery 10. For example, the charging circuit 30 charges the battery 10 with power received from a charging voltage VCH supplied to a node NIN. For example, the charging circuit 30 charges the battery 10 by generating and supplying a charging current ICH based on the charging voltage VCH. The charging voltage VCH is a power supply voltage for charging. Specifically, the charging circuit 30 charges the battery 10 using constant-current charging or constant-current-converted (CCCV) charging. In CCCV charging, the battery 10 is first charged with a constant current, which is CC charging, and then switched to constant-voltage charging, which is CV charging. For example, the battery 10 is charged using constant-current charging, and when the battery voltage VBAT reaches a predetermined voltage, the charging circuit 30 switches from constant-current charging to constant-voltage charging. Note that the power received using the charging voltage VCH may be power received via contactless power transmission as shown in FIG. 3 (described later) or via contact-type power transmission via a wire. That is, charging by the charging circuit 30 may be wireless charging or contact-type charging. The charging voltage VCH is, for example, 5V to 4V, and the battery voltage VBAT is, for example, 4.3V to 3.6V.

[0019] The control circuit 50 performs various control processes and arithmetic processes. 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.

[0020] The battery 10 is provided with a protection circuit 12 that protects the battery 10. This protection circuit 12 enters a shutdown state when the battery 10 is in an over-discharge state. For example, the protection circuit 12 is connected to the battery 10. Specifically, the protection circuit 12 is built into a battery pack that houses the battery 10 and connected to the battery 10. When the protection circuit 12 detects an over-discharge state of the battery 10, it turns off the switch SW1 to prevent discharging of the battery 10 and enters a shutdown state, as described above. When the protection circuit 12 enters a shutdown state, the voltage difference between the voltage VP at the terminal TVP and the voltage VM at the terminal TVM becomes 0V. By entering the shutdown state in which the potential difference between the voltages VP and VM is 0V, the current consumption of the ICs in the protection circuit 12 becomes zero, preventing current consumption through the protection circuit 12 when the battery 10 is in an over-discharge state.

[0021] When the shutdown state of the protection circuit 12 is released, the control circuit 50 causes the charging circuit 30 to increase the charging current from an initial current value greater than zero and start constant current charging of the battery 10. For example, in this embodiment, the charging current is increased to a target current value, and then constant current charging of the battery 10 is performed. However, if an attempt is made to increase the charging current from an initial current value of zero to perform constant current charging when the shutdown state of the protection circuit 12 is released, a period of time will occur during which no current flows due to the initial current value of zero, causing the protection circuit 12 to return to the shutdown state again.

[0022] Therefore, in this embodiment, when the shutdown state of the protection circuit 12 is released, the control circuit 50 causes the charging circuit 30 to supply a charging current with an initial current value greater than zero, and then increases the charging current from that initial current value to start constant current charging. In this way, when the shutdown state is released, an initial current value greater than zero flows, preventing a period of no current from occurring. This prevents the protection circuit 12, which has been released from the shutdown state, from returning to the shutdown state, and allows appropriate constant current charging of the battery 10 to begin.

[0023] Fig. 2 shows a detailed configuration example of the circuit device 20 and electronic device 2 of this embodiment. In Fig. 2, in addition to the charging circuit 30 and control circuit 50, the circuit device 20 is further provided with a voltage measurement circuit 40 and a storage 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 these components or adding other components.

[0024] The charging circuit 30 includes a first charging circuit 31 and a second charging circuit 32. The first charging circuit 31 is a circuit that performs constant current charging. Specifically, the first charging circuit 31 performs constant current charging by supplying a constant charging current ICH. When a shutdown state of the battery 10 due to over-discharge is detected, the second charging circuit 32 first supplies the charging current ICH to charge the battery 10. As the second charging circuit 32 charges the battery 10 in this manner, the shutdown state of the protection circuit 12 is released. When the shutdown state of the protection circuit 12 is released in this manner, the first charging circuit 31 begins constant current charging of the battery 10 by increasing the charging current from an initial current value. Specifically, the first charging circuit 31 performs step-up current charging, which increases the charging current from an initial current value greater than zero, and then performs constant current charging when the charging current reaches a target current value.

[0025] 2, the second charging circuit 32 includes a resistor RC and a switch SW for supplying a current to the battery 10 to release the shutdown state of the protection circuit 12. For example, the resistor RC and the switch SW are connected in series between a node NIN, to which a charging voltage VCH is supplied to the charging circuit 30, and a node NB, to which a charging current ICH to the battery 10 is output. When the shutdown state of the protection circuit 12 is detected, the switch SW turns on. As a result, the charging current ICH flowing via the resistor RC is supplied to the battery 10 as a current to release the shutdown state of the protection circuit 12.

[0026] The voltage measurement circuit 40 measures the battery voltage VBAT. The battery voltage VBAT corresponds to, for example, the voltage VP at the positive terminal 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.

[0027] The control circuit 50 then detects the release of the shutdown state of the protection circuit 12 based on the measurement result of the battery voltage VBAT by the voltage measurement circuit 40. For example, when the shutdown state of the protection circuit 12 is detected, the control circuit 50 first causes the second charging circuit 32 to charge the battery 10. This charging by the second charging circuit 32 causes the protection circuit 12 to release the shutdown state in which the potential difference between the voltage VP and the voltage VM becomes 0 V. At this time, the control circuit 50 detects the release of the shutdown state based on the measurement result of the battery voltage VBAT by the voltage measurement circuit 40. For example, when the battery voltage VBAT increases due to the release of the shutdown state and reaches a predetermined detection voltage, the control circuit 50 determines that the shutdown state has been released. The control circuit 50 then causes the first charging circuit 31 to increase the charging current from an initial current value greater than zero to begin constant current charging of the battery 10.

[0028] The storage unit 60 stores various information and is realized by a storage circuit such as a memory or a register. The storage unit 60 stores the initial current value and step-up current value of the step-up current, which will be described in detail later. Alternatively, the storage unit 60 may store the initial current value and step-up time of the step-up current.

[0029] 2, the protection control circuit 13 includes a detection circuit 15 and a shutdown circuit 16. The detection circuit 15 detects an over-discharge state of the battery 10. The detection circuit 15 can also detect an over-charge state of the battery 10.

[0030] For example, the detection circuit 15 includes a ladder resistor circuit connected between a high-side power supply voltage VDD based on the voltage VP and a low-side power supply voltage VSS based on the voltage VM. VDD and VSS are used, for example, as power supply voltages for the protection circuit 12. The detection circuit 15 also includes a comparator that compares the divided voltage of the ladder resistor circuit with an overdischarge determination voltage and detects an overdischarge state of the battery 10 based on the output of this comparator. The detection circuit 15 also includes a comparator that compares the divided voltage of the ladder resistor circuit with an overcharge determination voltage and detects an overcharge state of the battery 10 based on the output of this comparator. Note that a sense resistor (not shown) may be provided so that the detection circuit 15 can detect overcurrents in charging and discharging currents.

[0031] The shutdown circuit 16 is implemented by a circuit that shorts the node of voltage VP and the node of voltage VM via a resistor when the protection circuit 12 is shut down. For example, the shutdown circuit 16 includes a resistor and a switch that are connected in series to the node of voltage VP and the node of voltage VM. When the protection circuit 12 is shut down, the switch is turned on, shorting the node of voltage VP and the node of voltage VM via the resistor. This causes the potential difference between voltage VP and voltage VM to become 0 V, resulting in a shutdown state.

[0032] Fig. 3 shows another detailed configuration example of the circuit device 20 and electronic device 2 of this embodiment. Fig. 3 shows a configuration example for wireless charging, in which the battery 10 is charged based on power received by contactless power transmission. In Fig. 3, 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. 3, and various modifications are possible, such as omitting some of the components or adding other components.

[0033] The power receiving circuit 70 receives the transmitted power from the power transmitting device 14 in a non-contact manner. That is, the power is received 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 including 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 generated in the secondary coil L2 into a DC rectified 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, i.e., a charging voltage VCH.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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).

[0038] 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.

[0039] 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 18. The power supply target device 18 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 18. 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 18.

[0040] The circuit device 20 is provided with a charging system circuit and a discharging system circuit. The charging system circuit operates based on the received power and charges the battery 10, which is the charging target. For example, the charging system circuit receives received power at a charging voltage VCH, operates based on the charging voltage VCH, 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 18.

[0041] 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.

[0042] FIG. 4 shows an example configuration of the charging circuit 30. Note that FIG. 4 also shows an example configuration of the first charging circuit 31 in FIG. 2. As shown in FIG. 4, the charging circuit 30 includes a current source circuit 36, an amplifier circuit OPA, a backflow prevention circuit 38, 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. 4, and various modifications are possible, such as omitting some of the components or adding other components.

[0043] The current source circuit 36 ​​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 36. 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.

[0044] The source of transistor TA is connected to node NIN, and the drain is connected to node NCS. Node NIN is supplied with a charging voltage VCH. Resistor RCS is provided between nodes NCS and NCSI. Resistor RS is provided between nodes NCS and 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. This causes a charging current ICH = (RCS / RS) × IS to be supplied to node NCSR, which is then supplied to node NB, the charging node, as charging current ICH.

[0045] The backflow prevention circuit 38 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.

[0046] 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. Then, to end charging of the battery 10, the control circuit 50 turns off transistor TB2 with a control signal SDB. This also turns off transistor TB1, and the backflow prevention circuit 38 prevents a backflow of charge from the battery 10 to the charging circuit 30.

[0047] 2. Initial current value of step-up current FIG. 5 is an explanatory diagram of CCCV charging. A1 in FIG. 5 shows the change in charging current ICH during CCCV charging, and A2 shows the change in charging voltage VCH. In CCCV charging, when charging begins, constant current charging is first performed at a target current value ITG. Then, when the battery voltage VBAT reaches a predetermined voltage, constant current charging is switched to constant voltage charging to charge the battery 10.

[0048] In this case, instead of setting the charging current to the target current value ITG immediately at the start of charging as shown in Figure 5, there is a step-up current method in which the charging current is increased in steps as shown in Figure 6. For example, in Figure 6, the charging current is increased in steps from an initial current value of zero, and when the charging current reaches the target current value ITG, constant current charging is performed at the target current value ITG.

[0049] In this embodiment, the initial current value of such a step-up current is set to a variable value. Specifically, the initial current value is set to a value greater than zero. Furthermore, the step-up current value or step-up time of the step-up current may be set to a variable value.

[0050] For example, in the case of charging using wireless power transfer as shown in FIG. 3, the received power PW available for charging is expressed by the relational expression PW = VCH × (ICH + IOP) - VBAT × ICH, where VCH is the charging voltage, VBAT is the battery voltage, ICH is the charging current, and IOP is the current consumption. In this case, if the charging current ICH is suddenly increased from zero to the target current value ITG using a charging circuit 30 capable of controlling the charging current with multi-bit resolution, as shown in FIG. 5, the charging voltage VCH will drop. For this reason, as shown in FIG. 6, step-up current charging is performed, in which the charging current ICH is gradually increased in steps up to the target current value ITG. At the same time, power control is used to gradually increase the transmitted power using the power transmitting device 14 in FIG. 3 to prevent VCH from dropping.

[0051] 1 to 3, a protection circuit 12 called a PCM is attached to a battery 10 such as a secondary battery, and when the protection circuit 12 is in a discharge-prohibiting state and a shutdown state, the battery voltage VBAT as seen from the circuit device 20, which is a charging device, becomes 0V. This is because in the shutdown state, the protection control circuit 13 shorts the node of voltage VP and the node of voltage VM via a resistor so that the potential difference between voltage VP and voltage VM becomes 0V.

[0052] 2, which can control the charging current with multi-bit resolution, cannot pass the charging current. For this reason, the shutdown state of the protection circuit 12 is released by charging from the second charging circuit 32, which passes the charging current via a resistor RC connected between the VCH node NIN and the VBAT node NB. When the shutdown state is released, the battery voltage VBAT of the battery 10 becomes visible to the circuit device 20, and constant current charging is performed, in which the charging current is passed by the first charging circuit 31, which can control the charging current with multi-bit resolution.

[0053] However, it has been found that after the shutdown state of the protection circuit 12 is released, if a step-up current is charged starting from an initial current value of zero (0 A), as shown in Figure 6, the initial current value of zero at the first step-up will cause the protection circuit 12 to return to the shutdown state again.

[0054] In addition to wireless charging as shown in Figure 3, step-up current charging may also be used in contact charging. For example, by stepping up the charging current in stages, the internal resistance of the battery 10 can be estimated from changes in current and battery voltage. For this reason, step-up current is also used in contact charging. However, if the step-up time is long in this case, it will take a long time to reach the target current value. For example, contact charging generally allows for a larger charging current than wireless charging, which can shorten the charging time. However, if the target current value is large, there is a problem in that the time it takes to reach the target current value using the step-up current will suppress the charging speed.

[0055] Therefore, in this embodiment, as shown in FIG. 7, the initial current value IINI of the step-up current can be set to any value. Alternatively, the step-up current value ISTP of the step-up current can be set to any value. Alternatively, as shown in FIG. 8, the step-up time TSTP of the step-up current can be set to any value. The step-up current value ISTP is the current difference between the first and second current values ​​when the charging current ICH is increased stepwise from the first current value to the second current value. It is the current increase of the second current value relative to the first current value. In other words, the charging current ICH is increased stepwise in units of the step-up current value ISTP. The step-up time TSTP is the time difference between the first and second timings when the charging current ICH of the first current value flows at the first timing and the charging current ICH of the second current value flows at the second timing. In other words, the charging current ICH is increased stepwise every step-up time TSTP.

[0056] FIG. 9 is an explanatory diagram illustrating the storage of the initial current value IINI and the like of the step-up current in the storage unit 60. For example, the initial current value IINI and the step-up current value ISTP of the step-up current described in FIG. 7 are stored in the storage unit 60. Alternatively, the initial current value IINI and the step-up current value ISTP or the step-up time TSTP of the step-up current described in FIG. 8 are stored in the storage unit 60. The initial current value IINI and the step-up current value ISTP or the step-up time TSTP 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 controls the charging circuit 30 based on the initial current value IINI and the step-up current value ISTP or the step-up time TSTP loaded in the register unit 62. The charging circuit 30 then performs charging with the step-up current as shown in FIG. 7 based on the initial current value IINI and the step-up current value ISTP. Alternatively, the charging circuit 30 performs charging with the step-up current as shown in FIG. 8 based on the initial current value IINI and the step-up current value TSTP.

[0057] In this embodiment, when the shutdown state of the protection circuit 12 is released, the control circuit 50 causes the charging circuit 30 to increase the charging current from an initial current value greater than zero, thereby initiating constant current charging of the battery 10. For example, as shown in FIGS. 7 and 8, when the shutdown state is released, the charging circuit 30 increases the charging current ICH in steps from an initial current value IINI greater than zero, and initiates constant current charging when the charging current ICH reaches a target current value ITG. This prevents the protection circuit 12 from returning to the shutdown state due to an initial current value IINI of zero flowing when the shutdown state of the protection circuit 12 is released. The charging current ICH is then increased from the initial current value IINI greater than zero, allowing constant current charging of the battery 10 to begin.

[0058] For example, if the battery voltage is lower than the over-discharge determination voltage detected by protection circuit 12, protection circuit 12 goes into a shutdown state and sets the potential difference between voltages VP and VM to 0 V. After the charging voltage is applied, circuit device 20, which is a charging device, recognizes that the potential difference between voltages VP and VM is 0 V, and then performs charging using second charging circuit 32 in FIG. 2, thereby releasing the shutdown state of protection circuit 12.

[0059] When the shutdown state is released in this way, the battery voltage +VF is detected between voltages VP and VM. That is, when the shutdown state is released and the short circuit between the node of voltage VP and the node of voltage VM caused by shutdown circuit 16 of protection control circuit 13 is released, the voltage obtained by adding the forward voltage VF, which is the result of the charging current from second charging circuit 32 flowing through diode DI1, to the battery voltage, becomes visible from circuit device 20. This enables charging by first charging circuit 31.

[0060] It was also discovered that if there is a period during which no charging current flows when switching from charging by the second charging circuit 32 to charging by the first charging circuit 31, the protection circuit 12 will return to the shutdown state again. That is, if the initial current value of the step-up current is zero as shown in Figure 6, the zero charging current will continue until the charging current increases from zero (0 A) during the first step-up, and the protection circuit 12 will return to the shutdown state again.

[0061] If the initial current value of the step-up current is zero, a shutdown state is detected, the shutdown state is released by charging the second charging circuit 32, and the charging current is increased from the initial current value of zero by the first charging circuit 31. This series of processes is repeated as long as the battery voltage is lower than the voltage for determining over-discharge.

[0062] In this embodiment, when the shutdown state is released, the charging current is increased from an initial current value greater than zero, thereby preventing the above-mentioned problems from occurring. Then, when the charging current is increased from the initial current value greater than zero and reaches the target current value, constant current charging begins, allowing the battery 10 to be properly charged.

[0063] FIG. 10 is a flowchart illustrating the operation of this embodiment. First, it is determined whether the shutdown state of the protection circuit 12 has been detected (step S1). For example, when the protection circuit 12 enters the shutdown state, the potential difference between the voltages VP and VM becomes 0 V. Therefore, the circuit device 20 detects whether the protection circuit 12 is in the shutdown state by detecting the potential difference between the voltages VP and VM. If the shutdown state is detected, charging by the second charging circuit 32 is initiated (step S2). For example, the second charging circuit 32 in FIG. 2 performs charging by flowing a charging current through resistor RC based on the voltage difference between VCH and VBAT. Then, it is determined whether the shutdown state of the protection circuit 12 has been released (step S3). For example, the battery voltage VBAT is measured by the voltage measurement circuit 40. If the shutdown state has been released, the first charging circuit 31 starts charging by a step current, increasing the charging current from an initial current value greater than zero (step S4). That is, as shown in FIGS. 7 and 8, the charging current is increased in a step-up manner from an initial current value IINI greater than zero. Then, it is determined whether the charging current has reached the target current value ITG, and if so, constant current charging by the first charging circuit 31 is started (steps S5 and S6).

[0064] As described above, the circuit device 20 of this embodiment includes a charging circuit 30 that charges the battery 10 and a control circuit 50 that controls the charging circuit 30, as shown in FIGS. 1 to 3 . The battery 10 is provided with a protection circuit 12 that shuts down when the battery 10 is in an over-discharge state. For example, the battery 10 and protection circuit 12 are housed in a battery pack. When the protection circuit 12 is released from the shutdown state, the control circuit 50 causes the charging circuit 30 to increase the charging current from an initial current value greater than zero and start constant current charging of the battery 10. For example, as shown in FIGS. 7 and 8 , the charging current is increased in a step-up manner from an initial current value greater than zero, and constant current charging is started when the charging current reaches a target current value.

[0065] In this way, when the shutdown state of the protection circuit 12 is released, the charging circuit 30 supplies a charging current with an initial current value greater than zero to the battery 10, preventing a period in which no charging current flows to the battery 10 after the shutdown state is released. This makes it possible to prevent the protection circuit 12 from returning to the shutdown state due to a period in which no current flows after the shutdown state is released. This makes it possible to properly execute charging control in which the charging current is increased from the initial current value to perform constant current charging after the shutdown state is released.

[0066] 2, the charging circuit 30 includes a first charging circuit 31 that performs constant current charging, and a second charging circuit 32. When the shutdown state of the protection circuit 12 is detected, the control circuit 50 causes the second charging circuit 32 to charge the battery 10. That is, charging is not immediately performed by the first charging circuit 31, which is capable of constant current charging, but rather charging is first performed by the second charging circuit 32. When the shutdown state of the protection circuit 12 is released, the first charging circuit 31 increases the charging current from an initial current value greater than zero, and constant current charging of the battery 10 begins.

[0067] In this way, when the protection circuit 12 is in a shutdown state, the shutdown state of the protection circuit 12 can be released by charging with the second charging circuit 32. After the shutdown state is released, the first charging circuit 31 can increase the charging current from an initial current value greater than zero to perform constant current charging.

[0068] 2, the second charging circuit 32 includes a resistor RC and a switch SW for supplying a current to the battery 10 to release the shutdown state.

[0069] In this way, when the protection circuit 12 is in the shutdown state, the second charging circuit 32 can supply a current through the resistor RC to the battery 10. By supplying this current through the resistor RC, the shutdown state of the protection circuit 12 can be released.

[0070] 2, the resistor RC and switch SW of the second charging circuit 32 are connected in series between a node NIN, at which the charging voltage VCH is supplied to the charging circuit 30, and a node NB, at which the charging current ICH to the battery 10 is output. The switch SW is turned on when a shutdown state is detected.

[0071] In this way, when a shutdown state is detected, the switch SW turns on, causing a current corresponding to the voltage difference between the charging voltage VCH and the battery voltage VBAT to flow through the resistor RC connected in series with the switch SW. This current is then supplied to the battery 10 via the resistor RC, allowing the shutdown state of the protection circuit 12 to be released.

[0072] 2 and 3, the circuit device 20 includes a memory unit 60 that stores an initial current value. That is, as shown in Fig. 9, the memory unit 60 stores an initial current value IINI of the step-up current. The initial current value IINI is the current value of the charging current that is initially output in the step-up current.

[0073] In this way, it becomes possible to read out an initial current value IINI that is greater than zero from the storage unit 60, increase the charging current from that initial current value IINI, and start constant current charging of the battery 10. For example, it becomes possible to increase the charging current from the initial current value IINI, and start constant current charging when the charging current reaches the target current value.

[0074] In addition, as shown in Figure 7, the control circuit 50 increases the charging current to the battery 10 by the charging circuit 30 from the initial current value IINI by a step-up current value ISTP and sets it to the target current value ITG, thereby causing the charging circuit 30 to perform constant current charging at the target current value ITG.

[0075] In this manner, after a charging current having an initial current value IINI greater than zero is supplied to the battery 10, the charging current can be increased from this initial current value IINI by a step-up current value ISTP. When the charging current reaches the target current value ITG, a constant charging current at the target current value ITG can be supplied to the battery 10. In this case, by changing the magnitude of the step-up current value ISTP, the time required to reach the target current value ITG can be adjusted. For example, if the target current value ITG is large, increasing the step-up current value ISTP can shorten the time required to reach the target current value ITG. For example, in the contact-type charging described above, even if the target current value ITG for constant current charging is large, increasing the step-up current value ISTP can shorten the time required to reach the target current value ITG.

[0076] 2 and 3, the circuit device 20 includes a memory unit 60 that stores a step-up current value ISTP. That is, as shown in Fig. 9, the memory unit 60 stores the step-up current value ISTP of the step-up current. The step-up current value ISTP is a current increase value when the charging current is increased stepwise by the step-up current.

[0077] In this way, it becomes possible to read the step-up current value ISTP from the memory unit 60, increase the charging current stepwise in units of the step-up current value ISTP, and start constant current charging of the battery 10. For example, it becomes possible to increase the charging current in units of the step-up current value ISTP, and start constant current charging when the charging current reaches the target current value ITG.

[0078] In addition, as shown in Figure 8, the control circuit 50 increases the charging current to the battery 10 by the charging circuit 30 from the initial current value IINI every step-up time TSTP and sets it to the target current value ITG, thereby causing the charging circuit 30 to perform constant current charging at the target current value ITG.

[0079] In this way, after a charging current of an initial current value IINI greater than zero is supplied to the battery 10, the charging current can be increased from this initial current value IINI for each step-up time TSTP. Then, when the charging current reaches the target current value ITG, a constant charging current at the target current value ITG can be supplied to the battery 10. In this case, by changing the step-up time TSTP, it is possible to adjust the time required to reach the target current value ITG. For example, if the target current value ITG is large, the time required to reach the target current value can be shortened by reducing the step-up time TSTP, making it possible to accommodate contact-type charging with a large target current value ITG.

[0080] 2 and 3, the circuit device 20 includes a memory unit 60 that stores the step-up time TSTP. That is, as shown in Fig. 9, the memory unit 60 stores the step-up time TSTP of the step-up current. The step-up time TSTP is the time interval when the charging current is increased stepwise by the step-up current.

[0081] In this way, it becomes possible to read the step-up time TSTP from the storage unit 60, increase the charging current stepwise for each step-up time TSTP, and start constant current charging of the battery 10. For example, it becomes possible to increase the charging current for each step-up time TSTP, and start constant current charging when the charging current reaches the target current value ITG.

[0082] 2 and 3, the circuit device 20 also includes a voltage measurement circuit 40 that measures the battery voltage VBAT of the battery 10. For example, the voltage measurement circuit 40 performs A / D conversion of the battery voltage VBAT and outputs the measurement result data to the control circuit 50. The control circuit 50 then detects whether the shutdown state of the protection circuit 12 has been released based on the measurement result of the battery voltage VBAT by the voltage measurement circuit 40.

[0083] In this way, when the shutdown state of the protection circuit 12 is released, the voltage measurement circuit 40 measures the battery voltage VBAT and outputs the measurement result to the control circuit 50, allowing the control circuit 50 to determine whether the shutdown state of the protection circuit 12 has been released. When the control circuit 50 detects that the shutdown state of the protection circuit 12 has been released based on the measurement result of the voltage measurement circuit 40, it becomes possible for the charging circuit 30 to increase the charging current from an initial current value greater than zero and start constant current charging of the battery 10.

[0084] 3, the circuit device 20 includes a power receiving circuit 70 that receives power supplied by contactless power transmission from the power transmitting device 14. The charging circuit 30 charges the battery 10 based on the power received by the power receiving circuit 70.

[0085] In this way, it becomes possible for the charging circuit 30 to charge the battery 10 based on the power received by the power receiving circuit 70 in a non-contact manner from the power transmitting device 14. When charging the battery 10 using power received in a non-contact manner in this way, if an attempt is made to immediately charge the battery 10 with a large charging current, problems such as a drop in the charging voltage VCH used by the charging circuit 30 occur. In this regard, in this embodiment, the charging current can be increased from the initial current value to charge the battery 10, thereby preventing the occurrence of the above problems that occur when immediately charging the battery 10 with a large charging current.

[0086] As described above, the circuit device of this embodiment includes a charging circuit that charges a battery and a control circuit that controls the charging circuit. The battery is also provided with a battery protection circuit that shuts down when the battery is over-discharged. When the protection circuit's shutdown state is released, the control circuit causes the charging circuit to increase the charging current from an initial current value greater than zero, thereby starting constant current charging of the battery.

[0087] In this way, when the protection circuit's shutdown state is released, the charging current is increased from an initial current value greater than zero, preventing the protection circuit from returning to the shutdown state due to a period of time when no charging current flows to the battery after the shutdown state is released. This makes it possible to achieve appropriate constant current charging of the battery even when using a protection circuit that shuts down when the battery is in an over-discharged state.

[0088] In this embodiment, the charging circuit may include a first charging circuit and a second charging circuit that perform constant current charging. The control circuit may then cause the second charging circuit to charge the battery when a shutdown state is detected, and may cause the first charging circuit to increase the charging current from an initial current value and start constant current charging of the battery when the shutdown state is released.

[0089] In this way, when the protection circuit is in a shutdown state, the shutdown state of the protection circuit is released by charging through the second charging circuit, and after the shutdown state is released, the first charging circuit increases the charging current from the initial current value to perform constant current charging.

[0090] In this embodiment, the second charging circuit may also include a resistor and a switch for supplying a current to the battery to release the shutdown state.

[0091] In this way, when the protection circuit is in a shutdown state, the second charging circuit supplies a current to the battery via the resistor, thereby enabling the protection circuit to be released from the shutdown state.

[0092] In this embodiment, the resistor and switch are arranged in series between a node to which a charging voltage is supplied to the charging circuit and a node to which a charging current is output to the battery, and the switch may be turned on when a shutdown state is detected.

[0093] In this way, a current corresponding to the voltage difference between the charging voltage and the battery voltage is passed through the resistor connected in series to the switch that has been turned on, thereby releasing the shutdown state of the protection circuit.

[0094] In this embodiment, a storage unit for storing the initial current value may also be included.

[0095] In this way, the charging current can be increased from the initial current value read out from the storage unit, and constant current charging can be started.

[0096] In addition, in this embodiment, the control circuit may cause the charging circuit to perform constant current charging at a target current value by increasing the charging current to the battery by a step-up current value from an initial current value to set it to a target current value.

[0097] In this way, the charging current can be increased from the initial current value to the target current value in units of step-up current values, and constant current charging can be started.

[0098] In addition, this embodiment may include a storage unit that stores the step-up current value.

[0099] In this way, the charging current can be increased stepwise in units of the step-up current value read from the storage unit, and constant current charging can be started.

[0100] In addition, in this embodiment, the control circuit may cause the charging circuit to perform constant current charging at a target current value by increasing the charging current to the battery from the charging circuit every step-up time and setting it to a target current value.

[0101] In this way, the charging current can be increased from the initial current value for each step-up time, and constant current charging can be started.

[0102] In addition, this embodiment may include a storage unit that stores the step-up time.

[0103] In this way, the charging current can be increased stepwise for each step-up time read from the storage unit, and constant current charging can be started.

[0104] In addition, this embodiment may include a power receiving circuit that receives power supplied from the power transmitting device through contactless power transmission, and the charging circuit may charge the battery based on the power received by the power receiving circuit.

[0105] This allows the charging circuit to charge the battery based on the power received by the power receiving circuit from the power transmitting device in a non-contact manner.The charging current can be increased from the initial current value to charge the battery, preventing problems that occur when a large charging current is used immediately.

[0106] The electronic device of this embodiment includes the circuit device described above, a battery, and a protection circuit.

[0107] 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, electronic devices, and protection circuits are not limited to those described in the present embodiment, and various modifications are possible. [Explanation of symbols]

[0108] 2...electronic device, 10...battery, 12...protection circuit, 13...protection control circuit, 14...power transmission device, 15...detection circuit, 16...shutdown circuit, 18...power supply target device, 20...circuit device, 30...charging circuit, 31...first charging circuit, 32...second charging circuit, 36...current source circuit, 38...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...rectification circuit, 80...power supply circuit Path, DI1, DI2...Diode, ICH...Charging current, IINI...Initial current value, ISTP...Step-up current value, ITG...Target current value, L1...Primary coil, L2...Secondary coil, OPA...Amplifier circuit, RB, RC, RCS, RS...Resistor, SW, SW1, SW2...Switch, TA, TB1, TB2...Transistor, TBAT, TVM, TVP, TVSS...Terminal, TSTP...Step-up time, VBAT...Battery voltage, VCH...Charging voltage, VP, VM...Voltage

Claims

1. a charging circuit for charging the battery; a control circuit for controlling the charging circuit; Including, The battery is provided with a protection circuit for the battery that shuts down when the battery is in an over-discharge state; The control circuit When the shutdown state of the protection circuit is released, the charging circuit increases the charging current from an initial current value greater than zero to start constant current charging of the battery.

2. 2. The circuit device according to claim 1, The charging circuit a first charging circuit that performs the constant current charging; a second charging circuit; Including, The control circuit causing the second charging circuit to charge the battery when the shutdown state is detected; When the shutdown state is released, the first charging circuit increases the charging current from the initial current value to start the constant current charging of the battery.

3. 3. The circuit device according to claim 2, The second charging circuit A circuit device comprising a resistor and a switch for supplying a current to the battery to release the shutdown state.

4. 4. The circuit device according to claim 3, the resistor and the switch are connected in series between a node to which a charging voltage is supplied to the charging circuit and a node to which the charging current to the battery is output; The circuit device is characterized in that the switch is turned on when the shutdown state is detected.

5. 2. The circuit device according to claim 1, A circuit device comprising: a storage unit that stores the initial current value.

6. 2. The circuit device according to claim 1, The control circuit A circuit device characterized in that the charging current to the battery by the charging circuit is increased from the initial current value by a step-up current value and set to a target current value, thereby causing the charging circuit to perform the constant current charging at the target current value.

7. 7. The circuit device according to claim 6, A circuit device comprising: a storage unit that stores the step-up current value.

8. 2. The circuit device according to claim 1, The control circuit A circuit device characterized in that the charging current to the battery by the charging circuit is increased from the initial current value for each step-up time and set to a target current value, thereby causing the charging circuit to perform the constant current charging at the target current value.

9. 9. The circuit device according to claim 8, A circuit device comprising: a storage unit that stores the step-up time.

10. 2. The circuit device according to claim 1, a voltage measurement circuit for measuring a battery voltage of the battery; The control circuit The circuit device detects release of the shutdown state based on the measurement result of the battery voltage by the voltage measurement circuit.

11. 2. The circuit device according to claim 1, a power receiving circuit that receives power supplied from a power transmitting device by non-contact power transmission; The charging circuit A circuit device that charges the battery based on the power received by the power receiving circuit.

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

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