Charging control device and battery pack

Abstract

To reduce the probability of failure in a charge control device or a battery pack.SOLUTION: A charge control device is used in a power supply set including a battery pack having a first terminal connected to an external device, a secondary battery connected to the first terminal, and a battery protection IC that prevents overcharging and overdischarging of the secondary battery by controlling a switch element provided on a discharge / discharge current path of the secondary battery, and controls charging of the secondary battery. The charge control device is configured to include an input protection IC having a first input terminal and a first output terminal, the first input terminal being connected to a charger or a charging terminal connectable to the charger, and having a protection function against overcurrent or overvoltage from the charger or the charging terminal, and a second input terminal connected to the first output terminal and a second output terminal connected to the external device and the first terminal, and having a function of controlling charging of the secondary battery.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a charge control device for a secondary battery or a battery pack having a charge control function for a secondary battery, and particularly to a technique that is effective for lithium secondary batteries, which require safety. [Background technology]

[0002] In recent years, high safety has been required for lithium secondary batteries, for example, and various protective measures have been proposed against overcharging, etc. For example, Patent Document 1 discloses a charge control device in which a charge control circuit controls the charging current from a charger to charge the secondary battery, and a protection circuit is provided separately from the charge control circuit to provide double protection in the event of an abnormality.

[0003] However, in the case of a battery pack with a charge control function, if a high voltage is input during charging due to an abnormality, or if a high voltage is generated due to a failure in an external device that receives power from the battery pack, the double protection disclosed in Patent Document 1 may not be sufficient. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-141572 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide a charge control device or a battery pack that is less likely to break down even when a high voltage is applied due to an abnormality or the like. [Means for solving the problem]

[0006] In order to solve the above problems, the present invention provides: A charge control device for controlling the charging of a secondary battery used in a power supply set including a battery pack having a first terminal connected to an external device, a secondary battery connected to the first terminal, and a battery protection IC that prevents overcharging and overdischarging of the secondary battery by controlling a switch element provided on a discharge / discharge current path of the secondary battery, the charge control device comprising: an input protection IC having a first input terminal and a first output terminal, the first input terminal being connected to a charger or a charging terminal connectable to the charger, and having a protection function against overcurrent or overvoltage from the charger; and a charge control IC having a second input terminal connected to the first output terminal and a second output terminal connected to the external device and the first terminal, and having a function of controlling the charging of the secondary battery. [Effects of the Invention]

[0007] According to the present invention, it is possible to reduce the probability of failure of the charge control device or the battery pack. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a configuration diagram illustrating an example of a charging control device according to an embodiment of the present invention and a system using the charging control device. [Figure 2] 2 is a configuration diagram showing an example of an input protection IC used in the charging control device according to the embodiment of FIG. 1. FIG. [Figure 3] 2 is a configuration diagram showing an example of a charge control IC used in the charge control device according to the embodiment of FIG. 1. FIG. [Figure 4] 2 is a configuration diagram showing an example of a battery protection IC used in the charge control device according to the embodiment of FIG. 1. FIG. [Figure 5] 1. FIG. 4 is a diagram showing an example of the configuration of a battery pack according to a modified example of the embodiment of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. 1 is a block diagram showing an example of a charge control device and a system using the same according to one embodiment of the present invention. In this embodiment, a combination of a charge control device 20 and a battery pack 50 is referred to as a power supply set 100.

[0010] 1, the charge control device 20 of this embodiment includes an input protection IC 21 and a charge control IC 22 provided between the charger 30 and the battery pack 50, a current limiting resistor R1 and a thermistor S1 connected to the external terminals of the input protection IC 21, a sense resistor R2 connected to the charge control IC 22, and capacitors C1 and C2 connected to the external terminals of the input protection IC 21 and the charge control IC 22, respectively. An external device 40 that operates by receiving power supply is connected to the output side of the power supply set 100.

[0011] The battery pack 50 includes a secondary battery 51, a battery protection IC 52, a discharge control switch T1, a charge control switch T2, resistors R3 and R4, a capacitor C3, and a thermistor S2. The discharge control switch T1 and the charge control switch T2 are configured, for example, by MOS transistors. The external device 40 is also equipped with a microcomputer 41 that controls the external device 40. The external device 40 is provided with a ground terminal GND for inputting a ground voltage. The ground terminal GND is connected to each component element (not shown) that makes up the external device 40, and has the function of grounding each component element. Examples of the external device 40 include electronic devices such as smartphones, and on-board control parts that control automobile systems.

[0012] The charger 30 is used to charge the secondary battery 51 in the battery pack 50 by supplying a voltage to the power supply set 100. The charger 30 is provided with a ground terminal GND for inputting a ground voltage. The ground terminal GND is connected to each component of the charger 30 and functions to ground each component. The charger 30 also includes a charging terminal that can be connected to the charger. An example of a charger 30 is an AC adapter. An example of a charging terminal that can be connected to the charger 30 is a terminal that complies with the Universal Serial Bus (USB) standard.

[0013] Here, input protection IC21 is a semiconductor device that has a protection function against overcurrent or overvoltage from charger 30, and includes, for example, an input terminal VIN1, an output terminal VUOT1, a current detection terminal (terminal ILIM), a temperature detection terminal (terminal TS), an information output terminal (terminal FAULT), an information input terminal (terminal CE), and a ground terminal GND. These terminals are, for example, external connection terminals (external terminals) for connecting the internal circuitry of input protection IC21 to the outside of input protection IC21.

[0014] A charger 30 is connected to an input terminal VIN1 of the input protection IC 21. A voltage is applied to the input terminal VIN1 from the charger 30, and the input protection IC 21 outputs from the output terminal VOUT1 such that the voltage and current do not exceed a predetermined voltage and a predetermined current. A capacitor C1 is connected between the charger 30 and the input terminal VIN1 of the input protection IC 21. One end of the capacitor C1 is connected to the charger 30 and the input terminal VIN1, and the other end is connected to ground. The capacitor C1 functions to reduce noise from the charger 30.

[0015] The terminal ILIM of the input protection IC 21 is grounded via a current limiting resistor R1. The input protection IC 21 detects the current value by detecting the voltage across the terminals of the current limiting resistor R1. The predetermined current can be changed by changing the resistance value of the current limiting resistor R1. Furthermore, terminal TS of input protection IC 21 is grounded via thermistor S1. Thermistor S1 is disposed near battery pack 50 and monitors the temperature of battery pack 50. Input protection IC 21 detects the voltage between the terminals of thermistor S1 from terminal TS, converts it into temperature, and has the function of limiting the voltage and current output from output terminal VOUT1 when a predetermined temperature is exceeded.

[0016] The terminals FAULT and CE of the input protection IC 21 are connected to the microcomputer 41 of the external device 40. The input protection IC 21 can output a signal from the terminal FAULT to the microcomputer 41. It can also receive a signal from the microcomputer 41 via the terminal CE. The ground terminal GND of the input protection IC 21 is connected to the ground voltage and is connected to each component of the input protection IC 21, and has the function of grounding each component.

[0017] FIG. 2 is a configuration diagram showing an example of the input protection IC 21 used in the charging control device 20 of the embodiment shown in FIG. As shown in FIG. 2, the input protection IC 21 includes a control circuit 211, a temperature detection circuit 212, a voltage monitoring circuit 214, a current monitoring circuit 215, and a switch circuit 216. The input terminal VIN1 and output terminal VOUT1 of the input protection IC 21 are connected by a power supply line, and a switch circuit 216 is disposed in the middle of this power supply line. The switch circuit 216 receives instructions from the control circuit 211 and controls the voltage and current output to the output terminal VOUT1. The switch circuit 216 also has a transistor, and by turning on this transistor, a current flows through the current limiting resistor R1 via the terminal ILIM. The switch circuit 216 may also include, for example, a current mirror circuit, which generates a current proportional to the output current and flows it through the current limiting resistor R1 via the terminal ILIM.

[0018] The voltage monitoring circuit 214 is configured to detect the voltage of the power line and monitor whether it exceeds a predetermined voltage. Here, exceeding the predetermined voltage is considered an "overvoltage state." The voltage monitoring circuit 214 can output an overvoltage detection signal to the control circuit 211 when an overvoltage state occurs. Upon receiving the overvoltage detection signal, the control circuit 211 controls the switch circuit 216 to limit the voltage output to the output terminal VOUT1 to a specified value or less. As a result, damage to the external device 40, the charging IC 22, and the battery pack 50 can be prevented.

[0019] The voltage monitoring circuit 214 can also detect a "low voltage state" where the voltage is lower than a predetermined voltage. When the voltage monitoring circuit 214 detects a low voltage state, it can output a low voltage detection signal to the control circuit 211. Upon receiving the low voltage detection signal, the control circuit 211 can control the switch circuit 216 to cut off the voltage output from the output terminal VOUT1. As a result, it is possible to prevent malfunctions caused by supplying unstable voltages to the external device 40, the charging IC 22, and the battery pack 50.

[0020] The current monitoring circuit 215 detects the current flowing through the power line and monitors whether it exceeds a predetermined current. Specifically, the current monitoring circuit 215 detects the current flowing from the power line through the terminal ILIM by converting it into a voltage using a current-limiting resistor R1 (FIG. 1) externally connected to the terminal ILIM. If the predetermined current is exceeded, this is considered an "overcurrent state." When the current monitoring circuit 215 detects an overcurrent state, it outputs an overcurrent detection signal to the control circuit 211. Upon receiving the overcurrent detection signal, the control circuit 211 controls the switch circuit 216 to limit the current output from the output terminal VOUT1 to a specified value or less. As a result, damage to the external device 40, the charging IC 22, and the battery pack 50 can be prevented.

[0021] The temperature detection circuit 212 detects the temperature from the voltage across the thermistor S1 via the terminal TS, and is configured to transmit a temperature abnormality signal to the control circuit 211 if the temperature deviates from a predetermined temperature. When the control circuit 211 receives the temperature abnormality signal, it controls the switch circuit 216 to limit the voltage output to the output terminal VOUT1 to a specified value or less. For example, by arranging the thermistor S1 in the battery pack 50, particularly near the secondary battery 51, it is possible to detect an abnormality in the secondary battery 51. In this case, if the temperature detection circuit 212 detects a temperature higher than the predetermined temperature, there is a risk of damage to the secondary battery 51. Therefore, the control circuit 211 can cut off the voltage supply from the charger 30 to the secondary battery 51 by controlling the switch circuit 216 to cut off the voltage output to the output terminal VOUT1.

[0022] Furthermore, rapid charging of the secondary battery 51 at low temperatures may accelerate deterioration. Therefore, when the temperature detection circuit 212 detects a temperature lower than a predetermined temperature, the control circuit 211 controls the switch circuit 216 to lower the voltage output to the output terminal VOUT1, thereby preventing rapid charging of the secondary battery 51 at low temperatures.

[0023] The control circuit 211 is configured to send an abnormality state signal to the external device 40 via the terminal FAULT when it detects an overvoltage state, an overcurrent state, or an abnormal temperature state. This allows the microcomputer 41 mounted in the external device 40 to determine that an abnormal state has occurred. As a result, the operation of the external device 40 can be stopped, and the external device 40 can be prevented from malfunctioning.

[0024] Furthermore, the control circuit 211 is configured to receive a signal sent from the external device 40 via the terminal CE and control the switch circuit 216. As a result, in response to a request from the external device 40, charging of the secondary battery 51 can be stopped or the voltage supplied to the external device 40 can be adjusted.

[0025] 1, an example of the configuration of the charge control IC 22 will be described. The charge control IC 22 includes, for example, an input terminal VIN2, an output terminal BAT, a current detection terminal (terminal ISNS), a temperature detection terminal (terminal TDET), and a ground terminal GND. These terminals are, for example, external terminals for connecting the internal circuit of the charge control IC 22 to the outside of the charge control IC 22. The input terminal VIN2 of the charge control IC 22 is connected to the output terminal VOUT1 of the input protection IC 21. One end of a capacitor C2 is connected to the input terminal VIN2, and the other end is grounded. The capacitor C2 functions to suppress fluctuations in the voltage supplied from the charge protection IC.

[0026] The output terminal BAT of the charge control IC 22 is connected to the terminal P+ of the battery pack 50. The charge control IC 22 outputs from the output terminal BAT a voltage and a current that are sufficient to appropriately charge the secondary battery 51 mounted in the battery pack 50, based on the voltage and current input to the input terminal VIN2. The output terminal BAT of the charge control IC 22 is also connected to the external device 40. Therefore, even when the secondary battery 51 is being charged, the external device 40 can be operated by supplying a voltage to the external device 40.

[0027] One end of the sense resistor R2 is connected to the terminal ISNS of the charge control IC 22. The charge control IC 22 is configured to convert the current output from the output terminal BAT into a voltage using the sense resistor R2 and detect the current. The charge control IC 22 is also configured to charge the secondary battery 51 with a constant current while monitoring the voltage across the sense resistor R2 used for current detection. The charge control IC 22 can also monitor the voltage at the terminal ISNS to which the sense resistor R2 is connected and stop charging if it detects an overcharge current. The charging control IC 22 is also configured to monitor the voltage of the output terminal BAT and charge the secondary battery 51 at a constant voltage. Furthermore, the charging control IC 22 can also stop charging if it detects an overvoltage state based on the voltage of the output terminal BAT.

[0028] Furthermore, the terminal TDET of the charge control IC 22 is connected to the thermistor S2 in the battery pack 50 via the terminal TC of the battery pack 50. The terminal TDET may also be directly connected to the thermistor S2. The charge control IC 22 detects the voltage between the terminals of thermistor S2 via the terminal TS, converts it into temperature, and can limit the voltage and current output from the output terminal BAT when a predetermined temperature is exceeded. The ground terminal GND of the charge control IC 22 is connected to the ground voltage and is connected to each component of the charge control IC 22, and has the function of grounding each component.

[0029] Fig. 3 is a configuration diagram showing an example of the charge control IC 22 used in the charge control device 20 of the embodiment in Fig. 1. The charge control IC 22 has a constant voltage control circuit 221, a voltage monitoring circuit 222, a temperature detection circuit 223, a current detection circuit 224, a constant current control circuit 225, a control circuit 226, a current monitoring circuit 227, and a charge control transistor T4.

[0030] The input terminal VIN2 and the output terminal BAT are connected by a power supply line, and a charge control transistor T4 is located in the power supply line. The charge control transistor T4 is, for example, a P-channel MOS transistor, and can control the voltage or current output from the output terminal BAT by changing the voltage at its gate electrode.

[0031] The constant voltage control circuit 221 detects the voltage at the output terminal BAT and generates a voltage that controls the charge control transistor T4. The current detection circuit 224 passes a current from the output terminal BAT to the terminal ISNS to which the sense resistor R2 is connected, and detects the current flowing to the output terminal BAT from the voltage across the sense resistor R2. The constant current control circuit 225 generates a voltage that controls the charge control transistor T4 from the current detected by the current detection circuit 224.

[0032] For example, if the secondary battery 51 is a lithium-ion battery, the constant voltage control circuit 221 and constant current control circuit 225 control the charge control transistor T4 to change the voltage and current at the output terminal BAT, enabling the following charging: Immediately after charging of the secondary battery 51 begins, preliminary charging begins at a current value of 0.1 C (10% of that during rapid charging), and when the battery voltage reaches 2.9 V, the charging mode switches to constant current charging (rapid charging), and when the battery voltage reaches 4.2 V, the charging mode switches to constant voltage charging and continues. Then, when the charging completion state (for example, when the charging current drops below a predetermined value) is detected, the charging control transistor T4 is turned off, and charging ends.

[0033] Furthermore, the charge control IC 22 has a voltage monitoring circuit 222 that monitors the voltage of the output terminal BAT to detect overvoltage, and a current monitoring circuit 227 that detects overcurrent from the current detected by the current detection circuit 224. When the voltage monitoring circuit 222 detects an overvoltage, it sends overvoltage detection information to the control circuit 226. When the current monitoring circuit 227 detects an overcurrent, it sends overcurrent detection information to the control circuit 226. When the control circuit 226 receives the overvoltage detection information or overcurrent detection information, it turns off the charge control transistor T4 and terminates charging. As a result, it is possible to prevent excessive voltage and current from being applied to the battery pack 50 and the external device 40. Furthermore, the output terminal BAT of the charge control IC 22 is also connected to the external device 40. Therefore, it is possible to detect overvoltage or overcurrent caused by a malfunction of the external device 40. As a result, it is possible to prevent a chain reaction of damage to the secondary battery 51 caused by a malfunction of the external device 40.

[0034] Furthermore, the temperature detection circuit 223 detects the temperature from the voltage across the terminals of thermistor S2 via terminal TDET and terminal TC of the battery pack 50, and can send a temperature abnormality signal to the control circuit 226 if the temperature is outside a predetermined temperature range. When the control circuit 226 receives the temperature abnormality signal, it turns off the charge control transistor T4 and terminates charging. For example, by placing the thermistor S2 near the secondary battery 51, it is possible to detect an abnormality in the secondary battery 51. At this time, if the temperature detection circuit 223 detects a temperature higher than the predetermined temperature, there is a risk of damage to the secondary battery 51. Therefore, the control circuit 226 can turn off the charge control transistor T4 and terminate charging.

[0035] Furthermore, rapid charging of the secondary battery 51 at low temperatures may accelerate deterioration. Therefore, when the temperature detection circuit 223 detects a temperature lower than a predetermined temperature, the control circuit 226 controls the charge control transistor T4 to forcibly perform pre-charging, thereby preventing deterioration of the secondary battery 51. Furthermore, the battery pack 50 includes multiple secondary batteries 51, and temperature differences may occur depending on the positions of the secondary batteries 51. Therefore, the charge control device according to this embodiment includes a thermistor S2 in addition to the thermistor S1. This allows the temperature of each secondary battery 51 to be measured accurately.

[0036] 1, an example of the configuration of the battery pack 50 will be described. As described above, the battery pack 50 includes the secondary battery 51, the battery protection IC 52, the discharge control switch T1, the charge control switch T2, the resistors R3 and R4, the capacitor C3, and the thermistor S2. The battery pack 50 also has an output terminal BAT of the charge control IC 22 and a terminal P+ connected to the external device 40. This terminal P+ is, for example, an external terminal for connecting the internal elements of the battery pack 50 to a device external to the battery pack 50. The ground terminal GND of the battery pack 50 is connected to a ground voltage. The ground terminal GND is connected to each component element of the battery pack 50 and has the function of grounding each component element.

[0037] The secondary battery 51 mounted in the battery pack 50 has a high-voltage terminal from which a high voltage is output and a low-voltage terminal from which a low voltage is output. The high-voltage terminal of the secondary battery 51 is connected to the terminal P+, and the low-voltage terminal is connected to a ground line (described later). That is, the secondary battery 51 is charged by the output terminal BAT of the charge control IC 22, and the charged voltage operates the external device 40.

[0038] The battery protection IC 52 mounted on the battery pack 50 includes, for example, a charge control terminal (terminal COUT), a discharge control terminal (terminal DOUT), a detection terminal (terminal VM), a power supply terminal (terminal VDD), and a ground terminal (terminal VSS). These terminals are, for example, external terminals for connecting the internal circuit of the battery protection IC 52 to the outside of the battery protection IC 52.

[0039] The high-voltage terminal of the secondary battery 51 is connected to the terminal VDD of the battery protection IC 52 via a resistor element R3, and the low-voltage terminal is connected to the terminal VSS of the battery protection IC 52. A capacitor C3 is disposed between the terminals VDD and VSS of the battery protection IC 52. The capacitor C3 has the function of suppressing fluctuations in the voltage from the secondary battery 51. The battery protection IC 52 can operate using the secondary battery 51 as a power source.

[0040] The low-voltage terminal of the secondary battery 51 is connected to a ground line connected to a ground terminal GND. The battery pack 50 has a discharge control switch T1 and a charge control switch T2 connected in series to a ground line connecting the ground terminal GND and the low-voltage terminal of the secondary battery 51. The battery protection IC 52 controls the charge control switch T2 to interrupt the ground line through which the charging current of the secondary battery 51 flows, and controls the discharge control switch T1 to interrupt the ground line through which the discharging current of the secondary battery 51 flows. The charge control switch T2 and the discharge control switch T1 are switching elements that switch the ground line between conductive and interrupted. The charge control switch T2 and the discharge control switch T1 are, for example, configured with N-channel MOS transistors.

[0041] Of these, the discharge control switch T1 has a parasitic diode between its drain and source, whose forward direction is opposite to the direction of the discharge current of the secondary battery 51. The discharge control switch T1 is a switch element inserted in series with the ground line so that the forward direction of the parasitic diode coincides with the direction of the charge current flowing through the secondary battery 51. The charge control switch T2 has a parasitic diode between its drain and source, whose forward direction is opposite to the direction of the charging current of the secondary battery 51. The charge control switch T2 is a switch element inserted in series with the ground line so that the forward direction of the parasitic diode coincides with the direction of the discharging current of the secondary battery 51.

[0042] The battery protection IC 52 has the function of protecting the secondary battery 51 from over-discharge, etc., by controlling the charge control switch T2 from the terminal DOUT and the charge control switch T2 from the terminal COUT. The terminal VM of the battery protection IC 52 is an example of a monitoring terminal used to monitor the potential on the ground side of the series circuit 53 of the switches T1 and T2, and is grounded via the resistor element R4.

[0043] 4 is a configuration diagram showing an example of the battery protection IC 52 used in the charge control device 20 of the embodiment shown in FIG. The detection circuit 532 is connected to the terminal VDD, terminal VSS, and terminal VM of the battery protection IC 52. The detection circuit 532 is used to monitor, for example, whether or not the external device 40 is connected, based on the voltage of the terminal VM.

[0044] Furthermore, the detection circuit 532 is configured to monitor the power supply voltage Vdd between the terminals VDD and VSS, thereby detecting overcharge of the secondary battery 51. The detection circuit 532 compares the power supply voltage Vdd with an overcharge detection voltage Vdet1, and when the power supply voltage Vdd is higher than the overcharge detection voltage Vdet1, generates an overcharge detection signal indicating that overcharge of the secondary battery 51 has been detected, and sends this to the control circuit 531.

[0045] Furthermore, the detection circuit 532 can detect over-discharge of the secondary battery 51 by monitoring the power supply voltage Vdd between the terminals VDD and VSS. The detection circuit 532 compares the power supply voltage Vdd with the over-discharge detection voltage Vdet2, and when the power supply voltage Vdd is lower than the over-discharge detection voltage Vdet2, it generates an over-discharge detection signal indicating that over-discharge of the secondary battery 51 has been detected and sends it to the control circuit 531.

[0046] Furthermore, the detection circuit 532 can detect a discharge overcurrent of the secondary battery 51 by monitoring the potential difference ΔV2 between the terminal VSS and the terminal VM. The detection circuit 532 compares the potential difference ΔV2 with a discharge overcurrent detection voltage Vdet3, and when the potential difference ΔV2 is higher than the discharge overcurrent detection voltage Vdet3 with the terminal VSS as the reference, the detection circuit 532 generates a discharge overcurrent detection signal indicating that a discharge overcurrent of the secondary battery 51 has been detected, and sends the signal to the control circuit 531.

[0047] Furthermore, the detection circuit 532 can detect a charging overcurrent of the secondary battery 51 by monitoring the potential difference ΔV2 between the terminal VSS and the terminal VM. The detection circuit 532 compares the potential difference ΔV2 with a charging overcurrent detection voltage Vdet4, and when the potential difference ΔV2 with respect to the terminal VSS is lower than the charging overcurrent detection voltage Vdet4, the detection circuit 532 generates a charging overcurrent detection signal indicating that a charging overcurrent of the secondary battery 51 has been detected, and sends the signal to the control circuit 531.

[0048] The control circuit 531 is connected to the terminal VDD, the terminal VSS, and the detection circuit 532. The control circuit 531 operates on the voltage supplied from the terminal VDD, receives a detection signal sent from the detection circuit 532, and is configured to output signals from the terminals COUT and DOUT to control the discharge control switch T1 and the charge control switch T2 on the charge / discharge current path of the secondary battery 51.

[0049] Here, when the detection circuit 532 detects overcharging of the secondary battery 51 for a predetermined detection delay time tVdet1, the control circuit 531 outputs a signal (for example, a low-level gate control signal) from the terminal COUT that switches the charge control switch T2 from on to off. Also, when the detection circuit 532 detects a charging overcurrent of the secondary battery 51 for a predetermined detection delay time tVdet4, the control circuit 531 outputs a signal (for example, a low-level gate control signal) from the terminal COUT that switches the charge control switch T2 from on to off.

[0050] Furthermore, when the detection circuit 532 detects over-discharge of the secondary battery 51 for a predetermined detection delay time tVdet2, the control circuit 531 outputs from the terminal DOUT a signal (for example, a low-level gate control signal) that switches the discharge control switch TR1 from on to off. When the detection circuit 532 detects a discharge overcurrent of the secondary battery 51 for a predetermined detection delay time tVdet3, the control circuit 531 outputs from the terminal DOUT a signal (for example, a low-level gate control signal) that switches the discharge control switch TR1 from on to off.

[0051] As a result, when abnormal charging (e.g., overcharging, excessive current in the charging direction (charging overcurrent) etc.) is detected by the detection circuit 232, the battery protection IC 52 can protect the secondary battery 51 from abnormal charging by turning off the charge control switch T2. Also, when abnormal discharging (e.g., overdischarging, excessive current in the discharging direction (discharging overcurrent) etc.) is detected by the detection circuit 532, the battery protection IC 52 can protect the secondary battery 51 from abnormal discharging by turning off the discharge control switch T1. In this embodiment, the series circuit 53 of the switches T1 and T2 is arranged on the ground line, but it may be arranged on the power supply line connecting the high potential terminal of the secondary battery 51 and the terminal P+.

[0052] As described above, the charge control device 20 according to this embodiment protects the secondary battery 51 from abnormal voltages using three ICs: the input protection IC 21, the charge control IC 22, and the battery protection IC 52. The purpose of the charge control IC 22 is to perform optimal charging to prevent deterioration of the secondary battery 51. For this reason, the withstand voltage of the charge control IC 22 is often set to around 5 V. Similarly, the purpose of the battery protection IC 52 is to prevent overcharging and over-discharging of the secondary battery. For this reason, the withstand voltage (rated voltage) of the battery protection IC 52 is often set to around 15 V. On the other hand, the purpose of the input protection IC 21 is to protect the circuit from high voltages and high currents due to faults, etc., so the electrical withstand voltage can be as high as around 30 V.

[0053] For example, even if a failure in the external device 40 generates a voltage exceeding the withstand voltage of the charge control IC 22, damaging the charge control IC 22, the input protection IC 21 is unlikely to be damaged. Furthermore, even if a failure in the external device 40 generates a voltage exceeding the withstand voltages of the charge control IC 22 and the battery protection IC 52, damaging the charge control IC 22, the input protection IC 21 is unlikely to be damaged. As a result, the input protection IC 21 can prevent excessive voltage from being applied to the secondary battery 51, preventing failure of the charge control device 20 or the battery pack 50 connected to the charge control device 20.

[0054] If the charging terminal connected to the charger 30 is a terminal that complies with the Universal Serial Bus (USB) standard, the input voltage control is weak, and there is a high possibility that a high voltage due to noise or the like will be input from an external power source to the charging control device 20. In the charging control device 20 according to this embodiment, the input protection IC 21 can prevent breakdown of the charging control device 20 or the battery pack 50 connected to the charging control device 20, even for a charger 30 with weak input voltage control.

[0055] Furthermore, if only a charger 30 with a sufficiently controlled external input (such as an AC adapter) is connected, protection by the input protection IC 21 is not necessary. In this case, it is possible to change to a charging control device that does not include the input protection IC 21. As a result, the charging control device can be made smaller because it does not include the input protection IC 21.

[0056] Furthermore, in the charge control device 20 according to this embodiment, a thermistor can be connected to each of the input protection IC 21 and the charge control IC 22. This allows the abnormality detection characteristics of the two thermistors to be set separately. For example, if the secondary battery 51 is made up of multiple secondary batteries connected in series, one thermistor can be placed near the secondary battery with a higher potential and another thermistor can be placed near the secondary battery with a lower potential. As a result, the temperature of the secondary battery 51 can be protected with high accuracy.

[0057] <Modification> As a modification of the embodiment in Fig. 1, a case where the functions of the charge control device according to the present invention are applied to a battery pack will be described. Fig. 5 shows an example of a battery pack according to a modification of the embodiment in Fig. 1. Note that the same circuits and elements as those in the embodiment in Fig. 1 are designated by the same reference numerals, and duplicated explanations will be omitted.

[0058] The battery pack 500 in Fig. 5, which is a modification of the embodiment in Fig. 1, includes an input protection IC 21, a charge control IC 22, a current limiting resistor R1, a sense resistor R2, capacitors C1 and C2, a thermistor S1, a thermistor S2, a secondary battery 24 (51), a battery protection IC 23 (52), a series circuit 26 (53) of switches T1 and T2, resistors R3 and R4, and a capacitor C3. In other words, the charge control device 20 according to the embodiment in Fig. 1 is incorporated into a battery pack.

[0059] 5 has an input terminal VIN, an output terminal VOUT, a ground terminal GND, and communication terminals D1 and D2. The input terminal VIN is connected to a charger 30 and is supplied with a voltage for charging a secondary battery 51. The output terminal VOUT is connected to an external device 40 and is supplied with a voltage for operating the external device 40. The communication terminals D1 and D2 are connected to a microcomputer 41 mounted on the external device 40 via communication terminals D3 and D4 of the external device 40. A ground voltage is applied to the ground terminal GND of the battery pack 500. The ground terminal GND is connected to each component of the battery pack 500 and has the function of grounding each component.

[0060] Here, the input terminal VIN1 of the input protection IC 21 is connected to the input terminal VIN of the battery pack 500, and the output terminal BAT of the charge control IC 22 and the high-voltage terminal of the secondary battery 51 are connected to the output terminal VOUT of the battery pack 500. The terminal FAULT of the input protection IC 21 is connected to the communication terminal D1, and the terminal CE is connected to the communication terminal D2. In other words, the modified example of FIG. 5 can operate in the same way as the embodiment of FIG. 1 and can achieve the same effects.

[0061] Although the embodiments of the present invention have been described above, the above embodiments are presented as examples and the present invention is not limited to the above embodiments. The above embodiments can be embodied in various other forms, and various combinations, omissions, substitutions, modifications, etc. can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as set forth in the claims. [Explanation of symbols]

[0062] 20...Charging control device, 21...Input protection IC, 22...Charging control IC, 30...Charger, 40...External device, 41...MCU, 50, 500...Battery pack, 51, 24...Secondary battery, 52, 23...Battery protection IC, 53, 26...Switch series circuit, 100...Power supply set, 211...Control circuit, 212...Temperature detection circuit, 214...Voltage monitoring circuit, 215...Current monitoring circuit, 216...Switch circuit, 221...Constant voltage control circuit, 222...Voltage monitoring circuit, 223...Temperature detection circuit, 224...Current detection circuit, 225...Constant current control circuit, 226...Control circuit, 227...Current monitoring circuit, 531...Control circuit, 532...Detection circuit

Claims

1. A charge control device used in a power supply set including a battery pack having a first terminal connected to an external device, a secondary battery connected to the first terminal, and a battery protection IC that prevents overcharging and overdischarging of the secondary battery by controlling a switch element provided on a discharge / discharge current path of the secondary battery, and controls charging of the secondary battery, an input protection IC having a first input terminal and a first output terminal, the first input terminal being connected to a charger or a charging terminal connectable to the charger, and having a protection function against overcurrent or overvoltage from the charger or the charging terminal; a charge control IC having a second input terminal connected to the first output terminal and a second output terminal connected to the external device and the first terminal, the charge control IC having a function of controlling charging of the secondary battery; A charging control device having the same.

2. further comprising a first thermistor and a second thermistor; the input protection IC has a terminal connected to the first thermistor; The charging control IC has a terminal connected to the second thermistor.

2. The charge control device according to claim 1, wherein:

3. The rated voltage of the input protection IC is set to a value greater than the rated voltage of the charge control IC.

2. The charge control device according to claim 1, wherein:

4. The output voltage of the first output terminal of the input protection IC is equal to or lower than the rated voltage of the charge control IC.

4. The charge control device according to claim 3.

5. The charging terminal is a terminal that complies with the Universal Serial Bus standard.

5. The charge control device according to claim 3 or 4.

6. a first terminal to which a voltage is input; a second terminal for outputting a voltage; a secondary battery having a high potential terminal connected to the second terminal and a low potential terminal; a battery protection IC that prevents overcharging and overdischarging of the secondary battery by controlling a switch element provided on a discharge current path of the secondary battery; an input protection IC having a first input terminal and a first output terminal, the first input terminal being connected to the first terminal, and having a protection function against an overcurrent or an overvoltage from the first terminal; a charge control IC having a second input terminal connected to the first output terminal and a second output terminal connected to the second terminal and the high potential terminal, and having a function of controlling charging of the secondary battery; A battery pack having

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