Semiconductor equipment

Abstract

In a semiconductor device equipped with an integrated circuit that controls the charging and discharging of a secondary battery, the integrated circuit is protected from abnormally high voltages applied to external terminals. [Solution] The semiconductor device is characterized by comprising: a first integrated circuit having a first external terminal connected to a secondary battery; a second external terminal electrically connected to the first external terminal and outputting a voltage received from the secondary battery to the outside; a third external terminal to which a signal is input or output to the outside; a first signal terminal that controls the charging and discharging of the secondary battery and inputs or outputs a signal; a second integrated circuit having a second signal terminal connected to the third external terminal; a third signal terminal connected to the first signal terminal; a first switch disposed between the second signal terminal and the third signal terminal; and an overvoltage protection circuit that shuts off the first switch when an overvoltage of the second signal terminal is detected.

Description

Technical Field

[0001] The present invention relates to a semiconductor device.

Background Art

[0002] A battery pack equipped with a secondary battery capable of supplying power to a portable electronic device or the like and a control IC (Integrated Circuit) that controls charging and discharging of the secondary battery is known. For example, the control IC has a communication unit that communicates data with a charger connected to the battery pack, and transmits required values of the charging voltage and charging current of the secondary battery to the charger via an external terminal.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] For example, in this type of battery pack, when a terminal of an external device such as a charger or an electronic device is connected to the external terminal of the battery pack, an abnormal high voltage may be applied to the external terminal. The control IC may be damaged due to the application of the abnormal high voltage. However, a technique for protecting the control IC from the abnormal high voltage applied to the external terminal has not been proposed, and improvement is necessary. Further, when a protection circuit for protecting the control IC from the abnormal high voltage is added to the battery pack, it is preferable to suppress the power consumption of the battery pack increased by the addition of the protection circuit.

[0005] The disclosed technique aims to protect an integrated circuit from an abnormal high voltage applied to an external terminal in a semiconductor device equipped with an integrated circuit that controls charging and discharging of a secondary battery.

Means for Solving the Problems

[0006] To solve the above technical problems, one embodiment of the present invention is a semiconductor device comprising: a first external terminal connected to a secondary battery; a second external terminal electrically connected to the first external terminal and outputting a voltage received from the secondary battery to the outside; a third external terminal to which a signal is input or output to the outside; a first integrated circuit having a first signal terminal that controls the charging and discharging of the secondary battery and inputs or outputs a signal; a second integrated circuit having a second signal terminal connected to the third external terminal; a third signal terminal connected to the first signal terminal; a first switch disposed between the second signal terminal and the third signal terminal; and an overvoltage protection circuit that shuts off the first switch when an overvoltage of the second signal terminal is detected. [Effects of the Invention]

[0007] In a semiconductor device equipped with an integrated circuit that controls the charging and discharging of a secondary battery, the integrated circuit can be protected from abnormally high voltages applied to external terminals. [Brief explanation of the drawing]

[0008] [Figure 1] This is an example of a block diagram showing one embodiment of a semiconductor device according to the present invention. [Figure 2] This is a state transition diagram showing an example of the operating mode transitions of a protection IC using the mode control circuit shown in Figure 1. [Modes for carrying out the invention]

[0009] The embodiments will be described below with reference to the drawings. In the following, the same reference numerals as the signal names may be used for signal lines, signal terminals, and signal nodes through which signals are transmitted. The same reference numerals as the voltage names may be used for voltage lines, voltage terminals, and voltage nodes through which voltage is supplied. In each drawing, the same reference numerals are used for identical components, and redundant explanations may be omitted.

[0010] (Example of a semiconductor device in one embodiment) Figure 1 is an example of a block diagram showing one embodiment of a semiconductor device according to the present invention. For example, the battery protection module 100 shown in Figure 1 is mounted on a battery pack 200 together with a secondary battery 300 such as a lithium-ion battery. The battery protection module 100 includes a control IC 110, a protection IC 120, transistors TR1 and TR2, resistors R1 and R2, and capacitors C1, C2, C3, and C4.

[0011] In Figure 1, the external terminals of the battery protection module 100 are shown as circles, and the internal terminals of the battery protection module 100 are shown as squares. For example, the external terminals of the battery protection module 100 are terminals provided on the connector for connecting the secondary battery 300 and the connector for connecting electronic equipment or a charger. The internal terminals are also the external terminals of the control IC 110 and the protection IC 120. The battery protection module 100 is an example of a semiconductor device. The control IC 110 is an example of a first integrated circuit, and the protection IC 120 is an example of a second integrated circuit.

[0012] The battery protection module 100 has external terminals B+, B-, P+, P-, E1, and E2. External terminals B+ and P+ are examples of a first external terminal and a second external terminal, respectively. External terminals E1 and E2 are examples of a third external terminal and a fourth external terminal, respectively, to which signals are input or output to the outside. External terminal B+ is connected to the positive terminal of the secondary battery 300, and external terminal B- is connected to the negative terminal of the secondary battery 300.

[0013] External terminals P+ and P- are connected to the power terminal and ground terminal of an electronic device (not shown), respectively. External terminals P+ and P- may also be connected to the power terminal and ground terminal of a charger (not shown), respectively. The charger may be connected to the battery pack 200 via an electronic device. External terminal P+ outputs the high voltage appearing at the positive terminal of the secondary battery 300 to the outside. External terminal P- outputs the low voltage appearing at the negative terminal of the secondary battery 300 to the outside. Although not particularly limited, for example, the secondary battery 300 outputs a maximum of 4.2V when fully charged.

[0014] For example, the electronic devices connected to the battery pack 200 are portable devices such as mobile phones, smartphones, tablets, and earphones. However, the electronic devices are not limited to portable devices; any device that can operate using the power of the secondary battery 300 when the battery pack 200 is connected to it is acceptable.

[0015] Resistor R1 and transistors TR1 and TR2 are an example of a third switch connected in series between external terminals B+ and P+. Resistor R2 and capacitor C1 are connected in series between external terminals B+ and B-. External terminal B- is connected to external terminal P-. Capacitors C2 and C3 are connected in series between the source of transistor TR1 and the source of transistor TR2. Capacitor C4 is connected between external terminals P+ and P-.

[0016] The control IC 110 has power terminals VDD1 and REG, ground terminal GND1, terminal BAT, charge control terminal COUT, discharge control terminal DOUT, terminals V+, S1, and S2. The protection IC 120 has power terminal VDD2, ground terminal GND2, and terminals CH1A, CH2A, CH3A, CH1B, CH2B, and CH3B. The power terminals REG and V+ are examples of the first power terminal and the third voltage terminal, respectively. Terminals S1 and S2 are examples of the first signal terminal and the fourth signal terminal, respectively, which input or output signals. The power terminal VDD2 and terminals CH1A, CH2A, CH3A, CH1B, CH2B, and CH3B are examples of the second power terminal, the second voltage terminal, the third signal terminal, the sixth signal terminal, the first voltage terminal, the second signal terminal, and the fifth signal terminal, respectively.

[0017] Furthermore, the protection IC120 includes an undervoltage protection circuit (UVP), a mode control circuit (MODE), resistors R3 and R4, switches SW1 and SW2, an overvoltage protection circuit (OVP), drivers DRV1, DRV2, and DRV3, and transistors TR3, TR4, and TR5. Resistors R3 and R4 are examples of the first and second resistors, respectively. Switches SW1 and SW2 are examples of the fourth and fifth switches, respectively. Transistors TR3, TR4, and TR5 are examples of the second, first, and sixth switches, respectively.

[0018] In control IC 110, the power terminal VDD1 is connected to external terminal B+ via resistor R2 and to external terminal B+ via capacitor C1. That is, resistor R2 and capacitor C1 are connected in series between external terminals B+ and B- via the connection node of power terminal VDD1. The ground terminal GND1 is connected to external terminals B+ and P-. The power terminal REG is connected to the power terminal VDD2 of protection IC 120. Terminal BAT is connected to external terminal B+ via resistor R1. The charge control terminal COUT is connected to the gate of transistor TR1, and the discharge control terminal DOUT is connected to the gate of transistor TR2. Terminal V+ is connected to terminal CH1A of protection IC 120. Terminal S1 is connected to terminal CH2A of protection IC 120, and terminal S2 is connected to terminal CH3A of protection IC 120.

[0019] Transistors TR1 and TR2 are, for example, N-channel MOSFETs (Metal Oxide Semiconductor Field Effect Transistors) and function as switches. Transistor TR1 has a parasitic diode DD, and transistor TR2 has a parasitic diode CD. The anode of parasitic diode DD is connected to the source of transistor TR1, and its cathode is connected to the drain of transistor TR1. The anode of parasitic diode CD is connected to the source of transistor TR2, and its cathode is connected to the drain of transistor TR2.

[0020] The control IC 110 outputs a charging control signal COUT for controlling conduction / blocking between the source and drain of the transistor TR1 to the gate of the transistor TR1. The transistor TR1 conducts while receiving a high-level charging control signal COUT and is blocked while receiving a low-level charging control signal COUT. Also, the control IC 110 outputs a discharging control signal DOUT for controlling conduction / blocking of the transistor TR2 to the gate of the transistor TR2. The transistor TR2 conducts while receiving a high-level discharging control signal DOUT and is blocked while receiving a low-level discharging control signal DOUT. Hereinafter, conduction and blocking between the source and drain of the transistor are referred to as on and off, respectively.

[0021] While the transistor TR1 is on and the transistor TR2 is off, a charging path from the external terminal P+ side to the positive electrode side of the secondary battery 300 is formed by the parasitic diode CD. On the other hand, while the transistor TR1 is off and the transistor TR2 is on, a discharging path from the positive electrode side of the secondary battery 300 to the external terminal P+ side is formed by the parasitic diode DD.

[0022] During charging of the secondary battery �00, the control IC 110 monitors the voltage of the external terminal P+ received at the terminal V+, and when it detects that the voltage of the external terminal P+ is higher than the overcharge detection voltage, it turns off the transistor TR1 to protect the secondary battery 300 from charging abnormalities such as overcharging. That is, the control IC 110 can detect an overvoltage of the external terminal P+ and turn off the transistor TR1 even when the voltage of the external terminal P+ is supplied to the terminal V+ of the control IC 110 via the protection IC 120, and can protect the secondary battery 300 from overvoltage.

[0023] Also, during discharging of the secondary battery 300, the control IC 110 monitors the voltage received at the terminal BAT, and when it detects that the voltage is lower than the overdischarge detection voltage, it turns off the transistor TR2 to protect the secondary battery 300 from discharging abnormalities such as overdischarge.

[0024] The control IC 110 operates by receiving the power supply voltage and ground voltage from the secondary battery 300 at the power supply terminal VDD1 and the ground terminal GND1. The control IC 110 also generates the power supply voltage VDD2 from the power supply voltage VDD1 using, for example, an internal regulator (not shown), and supplies the generated power supply voltage VDD2 to the power supply terminal VDD2 of the protection IC 120 via the power supply terminal REG. For example, the value of the power supply voltage VDD2 may be the same as the value of the power supply voltage VDD1, or it may be lower than the power supply voltage VDD1. When the power supply voltage VDD1 falls below a predetermined value, the power supply voltage VDD2 decreases in accordance with the decrease in power supply voltage VDD1.

[0025] Terminals S1 and S2 are electrically connected to external terminals E1 and E2, respectively, via the protection IC 120. For example, external terminals E1 and E2 receive sensor data detected by various sensors mounted on electronic equipment when the electronic equipment is connected to the battery protection module 100. For example, the various sensors include a temperature sensor that detects the temperature of the electronic equipment and a pressure sensor that detects the expansion of the electronic equipment. If the sensor data received by terminals S1 and S2 indicates an abnormality, the control IC 110 turns off transistors TR1 and TR2 and stops charging and discharging the secondary battery 300. For example, the sensor data is I 2 The data is transmitted using a C interface, with terminal S1 being the clock terminal and terminal S2 being the data terminal.

[0026] The control IC 110 may also detect the state of the secondary battery 300 (remaining capacity, fully charged) based on the voltage received at terminal BAT during discharge or charging of the secondary battery 300. The control IC 110 then transmits the detected state to the charger via terminals S1, S2, protection IC 120, and external terminals E1, E2. Upon receiving the state of the secondary battery 300, the charger transmits a charging instruction or a charging stop instruction to terminals S1, S2 of the control IC 110 via external terminals E1, E2, and protection IC 120. The control IC 110 controls transistors TR1, TR2 according to the received instruction to start charging the secondary battery 300 or stop charging the secondary battery 300.

[0027] The protection IC 120 operates using the power supply voltage VDD2 supplied from the control IC 110 or the voltage CH1B received at terminal CH1B, and the ground voltage received at the ground terminal GND2. In the protection IC 120, terminal CH1A is connected to terminal V+ of the control IC 110, terminal CH2A is connected to terminal S1 of the control IC 110, and terminal CH3A is connected to terminal S2 of the control IC 110. Terminal CH1B is connected to external terminal P+, terminal CH2B is connected to external terminal E1, and terminal CH3B is connected to external terminal E2. The ground terminal GND2 is connected to external terminals P- and B-. Capacitor C4 is connected between external terminals P+ and P-.

[0028] For example, transistors TR3, TR4, and TR5 are N-channel MOSFETs and function as switches. Transistor TR3 is located between terminals CH1A and CH1B and operates by receiving a control signal from driver DRV1 at its gate. Transistor TR4 is located between terminals CH2A and CH2B and operates by receiving a control signal from driver DRV2 at its gate. Transistor TR5 is located between terminals CH3A and CH3B and operates by receiving a control signal from driver DRV3 at its gate.

[0029] For example, each switch SW1 and SW2 may be a transistor such as a MOSFET. Switches SW1 and SW2 are exclusively turned on by a switch control circuit (not shown), and the power supply voltage VDD2 or voltage CH1B is supplied as the internal power supply voltage IVDD to the internal power line IVDD in the protection IC120. The internal power supply voltage IVDD is supplied to the internal circuit of the protection IC120. In this way, the power supply voltage VDD2 and voltage CH1B are used as the operating power supply for the protection IC120. The protection IC120 may also have a regulator that converts the voltages of the power line VDD2 and terminal CH1B, respectively, received via switches SW1 and SW2, into the internal power supply voltage IVDD.

[0030] By operating switches SW1 and SW2 exclusively, the through-current between terminal CH1B and power terminal VDD2 caused by both switches SW1 and SW2 being turned on simultaneously can be suppressed. As a result, damage to the control IC 110 or protection IC 120 due to through-current can be prevented.

[0031] Furthermore, even when switches SW1 and SW2 are temporarily turned on simultaneously, the resistor R3 placed between the power terminal VDD2 and switch SW1, and the resistor R4 placed between terminal CH1B and switch SW2, can mitigate the through-current flowing between the power line VDD2 and terminal CH1B. This allows for the temporary simultaneous turning of switches SW1 and SW2 when they are switched on or off, even when the exclusive on / off (conductive) switching of switches SW1 and SW2 is performed with a single control signal. Consequently, the configuration of the circuit that controls the switching of switches SW1 and SW2 can be simplified, and the power consumption of the protection IC 120 can be reduced. As a result, the cost and power consumption of the battery protection module 100 can be reduced.

[0032] For example, the protection IC 120 controls the supply of the voltage received at terminal CH1B to the internal power line IVDD, prioritizing it over the power supply voltage VDD2 received at power supply terminal VDD2. When the charger is connected to the battery protection module 100, transistor TR1 is turned on, and the secondary battery 300 is being charged, the protection IC 120 turns on only switch SW2. Also, when the charger is disconnected from the battery protection module 100, transistor TR2 is turned on, and the secondary battery 300 is being discharged, the protection IC 120 turns on only switch SW2.

[0033] On the other hand, when the charger is disconnected from the battery protection module 100, and the discharge voltage of the secondary battery 300 is lower than a predetermined voltage, and transistors TR1 and TR2 are turned off, the external terminals P+ and CH1B become floating. In this case, the protection IC 120 turns on only switch SW1.

[0034] Thus, the protection IC 120 turns on only switch SW2 when voltage is supplied to terminal CH1B, and turns on only switch SW1 when no voltage is supplied to terminal CH1B. The battery protection module 100 can detect whether a charger or electronic device is connected to the battery protection module 100 by monitoring the voltage of the external terminal P-.

[0035] The overvoltage protection circuit OVP outputs a control signal TCNT2 to drivers DRV1, DRV2, and DRV3, respectively, which turns off transistors TR3, TR4, and TR5, when the voltage at power terminal VDD2 or terminals CH1B, CH2B, or CH3B indicates an overvoltage. This prevents the overvoltage from being applied to the control IC 110 even if an overvoltage from any of the external terminals P+, E1, or E2 is applied to the battery protection module 100, thereby preventing damage to the control IC 110.

[0036] Furthermore, the overvoltage protection circuit OVP may output a control signal TCNT2 to driver DRV1 only if only the voltage at terminal CH1B indicates an overvoltage, thereby turning off transistor TR3. Similarly, the overvoltage protection circuit OVP may output a control signal TCNT2 to driver DRV2 only if only the voltage at terminal CH2B indicates an overvoltage, thereby turning off transistor TR4. Likewise, the overvoltage protection circuit OVP may output a control signal TCNT2 to driver DRV3 only if only the voltage at terminal CH3B indicates an overvoltage, thereby turning off transistor TR5.

[0037] For example, overvoltages at terminals CH1B, CH2B, and CH3B occur when a charged electronic device or a charged charger is connected to the battery protection module 100. The overvoltage protection circuit OVP may be configured to detect overvoltages if any of the voltages at terminals CH1B, CH2B, and CH3B exceed the rated voltages of terminals V+, S1, and S3 of the control IC 110, by setting the overvoltage determination voltage by a voltage determination unit (not shown) provided within the overvoltage protection circuit OVP.

[0038] Furthermore, the overcharge detection voltage that turns off transistor TR1 is lower than the overvoltage at terminal CH1B that turns off transistor TR3 of protection IC 120. Therefore, when the overcharge detection voltage is supplied to terminal V+ of control IC 110, transistor TR3 will not be turned off by the overcharge detection voltage. Consequently, even when protection IC 120, which protects control IC 110, is provided in the battery protection module 100, control IC 110 can detect the overvoltage at external terminal P+ and turn off transistor TR1, thereby protecting the secondary battery 300 from charging abnormalities such as overcharging.

[0039] Furthermore, the protection IC 120 may have a circuit to protect itself from overvoltages at terminals CH1B, CH2B, and CH3B. For example, the protection IC 120 may have a diode (not shown) between each terminal CH1B, CH2B, and CH3B and the ground terminal GND2, with its anode connected to the ground terminal. The diode may be a parasitic diode.

[0040] For example, the rated voltages of terminals V+, S1, and S3 of the control IC 110 are lower than the rated voltages of terminals CH1B, CH2B, and CH3B of the protection IC 120. Therefore, if a voltage higher than the rated voltages of terminals V+, S1, and S3, but lower than the rated voltages of terminals CH1B, CH2B, and CH3B is applied to the control IC 110 from outside the battery protection module 100, the control IC 110 may be damaged.

[0041] However, in this embodiment, the overvoltage protection circuit OVP turns off transistors TR3, TR4, and TR5 if the voltage of any of terminals CH1B, CH2B, and CH3B exceeds the rated voltage of terminals V+, S1, and S3 of the control IC110. This protects the control IC110 from overvoltages applied to external terminals P+, E1, and E2 even when the rated voltages of terminals V+, S1, and S3 are lower than the rated voltages of terminals CH1B, CH2B, and CH3B.

[0042] The undervoltage protection circuit UVP outputs a control signal TCNT1 to drivers DRV1, DRV2, and DRV3 that turns off transistors TR3, TR4, and TR5, respectively, when the power supply voltage VDD2 received through resistor R3 falls below a preset voltage V1. Voltage V1 is an example of a first voltage. It is not particularly limited, but voltage V1 may be, for example, 1.7V. The undervoltage protection circuit UVP outputs a control signal TCNT1 to drivers DRV1, DRV2, and DRV3 that turns on transistors TR3, TR4, and TR5, respectively, when the power supply voltage VDD2 is equal to or greater than voltage V1.

[0043] Furthermore, each driver DRV1, DRV2, and DRV3 will turn off transistors TR3, TR4, and TR5 if either control signal TCNT1 or TCNT2 indicates that transistors TR3, TR4, and TR5 are off. Each driver DRV1, DRV2, and DRV3 will turn on transistors TR3, TR4, and TR5 if both control signals TCNT1 and TCNT2 indicate that transistors TR3, TR4, and TR5 are on.

[0044] Furthermore, the undervoltage protection circuit UVP outputs an active-level undervoltage signal LV to the mode control circuit MODE, indicating an undervoltage abnormality in the power supply voltage VDD2, when the power supply voltage VDD2 falls below voltage V1. The undervoltage protection circuit UVP outputs an inactive-level undervoltage signal LV to the mode control circuit MODE, indicating that the power supply voltage VDD2 is normal, when the power supply voltage VDD2 is at or above voltage V1.

[0045] When the mode control circuit MODE receives an active-level low-voltage signal LV from the low-voltage protection circuit UVP indicating a low-voltage anomaly in the power supply voltage VDD2, it switches the operating mode of the protection IC 120 from normal mode to low-voltage protection mode. While in low-voltage protection mode, if the mode control circuit MODE receives an inactive-level low-voltage signal LV from the low-voltage protection circuit UVP indicating that the power supply voltage VDD2 is normal, it deactivates the low-voltage protection mode and switches the protection IC 120 back to normal mode.

[0046] The mode control circuit MODE, when detecting that the voltage CH1B received through resistor R4 falls below voltage V2 during low-voltage protection mode, outputs an active-level standby mode signal STBY, transitioning the protection IC 120 from low-voltage protection mode to standby mode. The mode control circuit MODE also outputs an inactive-level standby mode signal STBY during normal mode and low-voltage protection mode.

[0047] Voltage V2 is an example of a second voltage. While not particularly limited, voltage V2 may be, for example, 1.0V, and is lower than voltage V1. Normal mode, low-voltage protection mode, and standby mode are examples of the first, second, and third modes, respectively. An example of the transitions in the operating modes of the protection IC 120 is shown in Figure 2.

[0048] For example, the overvoltage protection circuit OVP, the undervoltage protection circuit UVP, and drivers DRV1, DRV2, and DRV3 operate in normal mode and undervoltage protection mode when an inactive-level standby mode signal STBY is output. Furthermore, the overvoltage protection circuit OVP, the undervoltage protection circuit UVP, and drivers DRV1, DRV2, and DRV3 cease operation in standby mode when an active-level standby mode signal STBY is output. The mode control circuit MODE operates in normal mode, undervoltage protection mode, and standby mode regardless of the level of the standby mode signal STBY.

[0049] This significantly reduces the power consumption of the protection IC 120 in standby mode compared to its power consumption in normal mode and low-voltage protection mode. As a result, even when the protection IC 120, which protects the control IC 110 from abnormally high voltages applied to the external terminals P+, E1, and E2, is mounted on the battery protection module 100, the increase in the power consumption of the battery protection module 100 can be suppressed. In particular, the effect of reducing the power consumption of the protection IC 120 is significant when the remaining capacity of the secondary battery 300 is low.

[0050] (Example of operation mode transitions for protection ICs) Figure 2 is a state transition diagram showing an example of the operation mode transitions of the protection IC 120 by the mode control circuit MODE in Figure 1. As described above, the operation mode of the protection IC 120 is one of the following, depending on the power supply voltage VDD2 and the voltage of terminal CH1B: normal mode, undervoltage protection mode, or standby mode. In normal mode, transistors TR3, TR4, and TR5 are turned on, and in undervoltage protection mode and standby mode, transistors TR3, TR4, and TR5 are turned off.

[0051] The protection IC120 switches off transistors TR3, TR4, and TR5, which are on, to exit normal mode and enter low-voltage protection mode if the power supply voltage VDD2 falls below voltage V1 while the power supply voltage VDD2 is at or above voltage V1 and the voltage at terminal CH1B is at or above voltage V2 (Figure 2(a)).

[0052] If the power supply voltage VDD2 is lower than voltage V1, the power supply voltage VDD1 supplied from the secondary battery 300 to the control IC 110 will also be lower than the normal value. When the power supply voltage VDD1 is lower than the normal value, the control IC 110 may not be able to correctly receive the signals supplied to terminals S1 and S2, and may not be able to output signals with the correct logic from terminals S1 and S2. In other words, the control IC 110 may not be able to operate normally.

[0053] When there is a risk that the control IC 110 may not function correctly, the protection IC 120 can be prevented from malfunctioning by turning off transistors TR4 and TR5 and stopping the reception of signals at terminals S1 and S2. Furthermore, when there is a risk that the control IC 110 may not function correctly, turning off transistors TR4 and TR5 and stopping the transmission of signals from terminals S1 and S2 to the outside can prevent malfunctions in electronic devices or chargers that receive the transmitted signals.

[0054] In low-voltage protection mode, when the voltage at terminal CH1B falls below V2 while the power line VDD2 is below V1 and the voltage at terminal CH1B is above V2, protection IC120 exits low-voltage protection mode and transitions to standby mode while maintaining the off state of transistors TR3, TR4, and TR5 (Figure 2(b)).

[0055] When the power line VDD2 is below voltage V1 and the voltage at terminal CH1B is below voltage V2, the protection IC 120 exits standby mode and switches to low-voltage protection mode when the voltage at terminal CH1B rises to or above voltage V2 (Figure 2(c)). For example, when a charger is connected to the battery protection module 100 and charging begins, and the voltage at terminal CH1B rises to 1V or higher, the protection IC 120 returns from standby mode to low-voltage protection mode.

[0056] Because the secondary battery 300 has a large capacity, the power supply voltages VDD1 and VDD2 rise with a delay compared to the rise in voltage at terminal CH1B. Therefore, if the system transitions directly from standby mode to normal mode when the voltage at terminal CH1B exceeds 1V, the control IC 110, which is not receiving the normal power supply voltage VDD1, may malfunction. However, by providing a low-voltage protection mode between standby mode and normal mode, malfunction of the battery protection module 100 can be suppressed.

[0057] When in low-voltage protection mode, if the power line VDD2 has a voltage of V1 or higher for more than time T1, the protection IC 120 turns on transistors TR3, TR4, and TR5, which are currently off, and exits low-voltage protection mode, transitioning to normal mode (Figure 2(d)). Time T1 is an example of the first time. Time T1 is set to be longer than the duration of contact chatter that occurs when the charger is connected to the battery protection module 100, for example, about 1 ms.

[0058] By setting time T1, it is possible to prevent the operating mode of the protection IC 120 from repeatedly changing. Furthermore, it is possible to prevent the control IC 110 from starting operation before the power supply voltages VDD1 and VDD2 rise to normal values. As a result, malfunctions of the control IC 110 and protection IC 120 can be prevented.

[0059] The overvoltage protection circuit (OVP) operates in normal mode and turns off transistors TR3, TR4, and TR5 when an overvoltage occurs at terminals CH1B, CH2B, and CH3B. The overvoltage protection circuit (OVP) stops operating in low voltage protection mode and standby mode, fixing transistors TR3, TR4, and TR5 in the off state.

[0060] Therefore, even if an electronic device or charger is connected to the battery protection module 100 during low-voltage protection mode or standby mode, and an overvoltage occurs at terminals CH1B, CH2B, and CH3B, the overvoltage will not be supplied to the control IC 110. In other words, by fixing transistors TR3, TR4, and TR5 in the off state during low-voltage protection mode and standby mode when the overvoltage protection circuit OVP stops operating, it is possible to prevent damage to the control IC 110 due to overvoltages occurring at terminals CH1B, CH2B, and CH3B during low-voltage protection mode and standby mode.

[0061] In the embodiments shown in Figures 1 and 2, the protection IC 120 turns off transistors TR3, TR4, and TR5 respectively when the voltage of the power supply terminal VDD2 or any of the terminals CH1B, CH2B, and CH3B indicates an overvoltage. This prevents the overvoltage from being applied to the control IC 110 even when an overvoltage from any of the external terminals P+, E1, or E2 is applied to the battery protection module 100, thereby preventing damage to the control IC 110. In other words, in a battery protection module 100 equipped with a control IC 110 that controls the charging and discharging of the secondary battery 300, the control IC 110 can be protected from abnormally high voltages applied to the external terminals P+, E1, and E2.

[0062] When charging the secondary battery 300, the control IC 110 turns off transistor TR1 if the voltage at the external terminal P+ received at terminal V+ exceeds the overcharge detection voltage. This protects the secondary battery 300 from charging abnormalities such as overvoltage or overcharge, even when the voltage at external terminal P+ is supplied to terminal V+ of the control IC 110 via the protection IC 120.

[0063] If the power supply voltage VDD1 is lower than the normal value and there is a risk that signals cannot be properly received or transmitted via terminals S1 and S2, the control IC 110 turns off transistors TR4 and TR5 and stops receiving signals via terminals S1 and S2. This prevents malfunction of the protection IC 120 that receives the signals, and prevents malfunction of electronic equipment or chargers that receive signals transmitted from the protection IC 120.

[0064] If the power supply voltage VDD1 is lower than the normal value and there is a risk that the control IC 110 may not be able to properly monitor the voltage supplied to terminal V+, the protection IC 120 will turn off transistor TR3 and stop supplying voltage to terminal V+. This prevents the protection IC 120 from malfunctioning.

[0065] When the voltage at terminal CH1B is lower than voltage V2, the protection IC 120 switches from low-voltage protection mode to standby mode, which stops the operation of most of its internal circuits. This significantly reduces the power consumption of the protection IC 120 in standby mode compared to its power consumption in normal mode and low-voltage protection mode. As a result, even when the protection IC 120, which protects the control IC 110 from abnormally high voltages, is mounted on the battery protection module 100, the increase in power consumption of the battery protection module 100 due to the protection IC 120 can be suppressed. The effect of reducing the power consumption of the protection IC 120 is particularly significant when the remaining capacity of the secondary battery 300 is low.

[0066] By switching from undervoltage protection mode to normal mode when the power line VDD2 has a voltage above V1 for more than a certain time T1, the operating mode of the protection IC 120 can be prevented from repeatedly changing, and the control IC 110 can be prevented from starting operation before the power supply voltages VDD1 and VDD2 rise to normal values. As a result, malfunctions of the control IC 110 and protection IC 120 can be prevented.

[0067] The overvoltage protection circuit OVP turns off transistors TR3, TR4, and TR5 if the voltage at any of terminals CH1B, CH2B, or CH3B exceeds the rated voltage of terminals V+, S1, or S3 of the control IC110. This protects the control IC110 from overvoltages applied to external terminals P+, E1, and E2, even if the rated voltages of terminals V+, S1, and S3 are lower than the rated voltages of terminals CH1B, CH2B, and CH3B.

[0068] By operating switches SW1 and SW2 exclusively, the through-current between terminal CH1B and power terminal VDD2 caused by both switches SW1 and SW2 being turned on simultaneously can be suppressed. As a result, damage to the control IC 110 or protection IC 120 due to through-current can be prevented.

[0069] The protection IC 120 has a resistor R3 placed between the power terminal VDD2 and switch SW1, and a resistor R4 placed between terminal CH1B and switch SW2. This allows for mitigation of the through-current flowing between the power line VDD2 and terminal CH1B even when switches SW1 and SW2 are temporarily turned on simultaneously. Therefore, it becomes possible to perform the exclusive on / off switching of switches SW1 and SW2 with a single control signal, simplifying the configuration of the circuit that controls the switching of switches SW1 and SW2. As a result, the power consumption of the protection IC 120 can be reduced, and the power consumption of the battery protection module 100 can be reduced.

[0070] Although the present invention has been described above based on various embodiments, the present invention is not limited to the requirements shown in the above embodiments. These points can be modified as long as they do not impair the spirit of the present invention, and can be appropriately determined according to their application. [Explanation of symbols]

[0071] 100 Battery Protection Modules 110 Control ICs 120 Protection IC 200 Battery Pack 300 Secondary battery B+, B- External terminal BAT terminal C1, C2, C3, C4 capacity CD parasitic diode CH1A, CH1B terminals CH2A, CH2B terminals CH3A, CH3B terminals COUT charging control terminal DD Parasitic Diode DOUT discharge control terminal DRV1, DRV2, DRV3 Drivers E1, E2 external terminals GND1, GND2 Grounding terminals IVDD internal power line LV Low Voltage Signal MODE Mode Control Circuit OVP Overvoltage Protection Circuit P+, P- External terminal R1, R2, R3, R4 resistance REG Power Terminal S1, S2 terminal STBY Standby Mode Signal SW1, SW2 switches TCNT1, TCNT2 control signals TR1, TR2, TR3, TR4, TR5 Transistors UVP Low Voltage Protection Circuit V+ terminal VDD1, VDD2 Power supply voltage

Claims

1. The first external terminal connected to the secondary battery, A second external terminal is electrically connected to the first external terminal and outputs the voltage received from the secondary battery to the outside, A third external terminal from which signals are input or output to the outside, A first integrated circuit having a first signal terminal that controls the charging and discharging of the secondary battery and inputs or outputs a signal, The second integrated circuit includes a second signal terminal connected to the third external terminal, a third signal terminal connected to the first signal terminal, a first switch positioned between the second and third signal terminals, and an overvoltage protection circuit that shuts off the first switch when an overvoltage is detected at the second signal terminal. A semiconductor device characterized by the following features.

2. The second integrated circuit includes a first voltage terminal connected to the second external terminal, a second voltage terminal, and a second switch positioned between the first voltage terminal and the second voltage terminal. The first integrated circuit has a third voltage terminal which is electrically connected to the second voltage terminal and to which the voltage of the second external terminal is supplied via the second integrated circuit. The overvoltage protection circuit further shuts off the second switch when it detects an overvoltage at the first voltage terminal. The semiconductor device according to feature 1.

3. The system further includes a third switch positioned between the first external terminal and the second external terminal, The first integrated circuit shuts off the third switch according to the value of the voltage at the second external terminal received at the third voltage terminal. The semiconductor device according to claim 2.

4. The first integrated circuit further has a first power supply terminal that outputs a power supply voltage generated based on the voltage supplied from the secondary battery, The second integrated circuit further has a second power supply terminal connected to the first power supply terminal, and when the voltage of the second power supply terminal becomes lower than the first voltage, it shuts off the first switch and transitions from the first mode to the second mode. The semiconductor device according to feature 1.

5. The second integrated circuit further has a first voltage terminal connected to the second external terminal, and when the voltage of the first voltage terminal falls below a second voltage which is lower than the first voltage during the second mode, it transitions to a third mode with lower power consumption than the power consumption of the first and second modes. The semiconductor device according to feature 4.

6. The second integrated circuit exits the third mode and returns to the second mode when the voltage at the first voltage terminal becomes equal to or greater than the second voltage during the third mode. The semiconductor device according to feature 5.

7. The second integrated circuit, when the voltage at the second power supply terminal exceeds the first voltage for a period of time exceeding the first time during the second mode, turns on the first switch, which was previously shut off, thereby disengaging the second mode and returning to the first mode. The semiconductor device according to feature 4.

8. The rated voltage of the first signal terminal of the first integrated circuit is lower than the rated voltage of the second signal terminal of the second integrated circuit. The overvoltage protection circuit shuts off the first switch when the voltage at the second signal terminal exceeds the rated voltage at the first signal terminal. The semiconductor device according to feature 1.

9. The second integrated circuit includes a first resistor and a fourth switch connected in series between the second power terminal and the internal power line, and a second resistor and a fifth switch connected in series between the first voltage terminal and the internal power line, wherein the fourth switch and the fifth switch are exclusively conductive, and the voltage supplied from the first integrated circuit to the second power terminal or the voltage supplied from the second external terminal to the first voltage terminal is supplied to the internal power line. The semiconductor device according to feature 5.

10. It further has a fourth external terminal on which signals are input or output, The first integrated circuit has a fourth signal terminal for inputting or outputting signals, The second integrated circuit includes a fifth signal terminal connected to the fourth external terminal, a sixth signal terminal connected to the fourth signal terminal, and a sixth switch positioned between the fifth signal terminal and the sixth signal terminal. The overvoltage protection circuit further shuts off the sixth switch when it detects an overvoltage at the fourth external terminal connected to the fifth signal terminal. The semiconductor device according to feature 1.

11. The first integrated circuit further has a first power supply terminal that outputs a power supply voltage generated based on the voltage supplied from the secondary battery, The second integrated circuit further has a second power supply terminal connected to the first power supply terminal, and when the voltage of the second power supply terminal becomes lower than the first voltage, it shuts off the first switch and the sixth switch, and transitions from the first mode to the second mode. The semiconductor device according to feature 10.

12. The second integrated circuit further has a first voltage terminal connected to the second external terminal, and when the voltage of the first voltage terminal falls below a second voltage which is lower than the first voltage during the second mode, it transitions to a third mode with lower power consumption than the power consumption of the first and second modes. The semiconductor device according to feature 11.

13. The second integrated circuit exits the third mode and returns to the second mode when the voltage at the first voltage terminal becomes equal to or greater than the second voltage during the third mode. The semiconductor device according to feature 12.

14. The second integrated circuit, when the voltage at the second power supply terminal exceeds the first voltage for a period of time exceeding the first time during the second mode, turns on the first and sixth switches, which were previously shut off, thereby exiting the second mode and returning to the first mode. The semiconductor device according to feature 13.

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