Secondary battery protection integrated circuit and battery device

Abstract

The invention provides a secondary battery protection integrated circuit and a battery device, which can properly protect a secondary battery from overdischarge. A secondary battery protection integrated circuit for protecting a secondary battery is provided with: a power supply terminal to which a positive electrode of the secondary battery can be connected; a ground terminal to which the negative electrode of the secondary battery can be connected; and a control circuit capable of controlling a discharge interruption circuit for interrupting discharge of the secondary battery, the control circuit performing a first operation when a power supply voltage between the power supply terminal and the ground terminal is equal to or greater than a first determination voltage higher than a second determination voltage, and performing a second operation when the power supply voltage between the power supply terminal and the ground terminal is equal to or greater than the second determination voltage. When a first condition that the power supply voltage is lower than the first determination voltage for a first time period is satisfied, the control circuit operates the discharge cut-off circuit. The control circuit operates the discharge cut-off circuit when a second condition that the power supply voltage is lower than the second determination voltage for a second period of time that is shorter than the first period of time is satisfied.

Description

Technical Field

[0001] This disclosure relates to a secondary battery protection integrated circuit and a battery device. Background Technology

[0002] Previously, an over-discharge prevention circuit was known, comprising: an over-discharge detection circuit for detecting over-discharge of a secondary battery; and a circuit for cutting off the discharge current based on the output level of the over-discharge detection circuit. In this over-discharge prevention circuit, when the battery voltage is lower than the determination voltage for over-discharge detection, the output level of the comparator is reversed, thereby turning off the transistor that cuts off the discharge current.

[0003] When using a single threshold voltage to detect over-discharge, the set threshold voltage value may not adequately protect the secondary battery from over-discharge. For example, when a large, temporary discharge current causes a significant drop in the secondary battery voltage, the set threshold voltage might mistakenly indicate over-discharge and cause the discharge to be unexpectedly cut off. Conversely, when the voltage drop caused by discharge is small, the set threshold voltage might not indicate over-discharge and might allow the secondary battery to continue discharging unexpectedly.

[0004] Patent Document 1: Japanese Patent Application Publication No. 5-49181 Summary of the Invention

[0005] This disclosure provides a secondary battery protection integrated circuit and a battery device that can appropriately protect a secondary battery from over-discharge.

[0006] This disclosure provides a secondary battery protection integrated circuit for protecting secondary batteries.

[0007] The secondary battery protection integrated circuit has the following features:

[0008] A power terminal that can be connected to the positive terminal of the secondary battery;

[0009] A grounding terminal, which can be connected to the negative terminal of the secondary battery; and

[0010] A control circuit that controls a discharge cutoff circuit used to cut off the discharge of the secondary battery.

[0011] When the power supply voltage between the power supply terminal and the ground terminal is higher than a first determination voltage (which is higher than the second determination voltage), the control circuit performs a first action.

[0012] When the first condition is met—that the power supply voltage is lower than the first determined voltage during a first time period—the control circuit causes the discharge cut-off circuit to operate.

[0013] When the second condition is met—that the power supply voltage is lower than the second determined voltage during a second time period shorter than the first time—the control circuit causes the discharge cut-off circuit to operate.

[0014] This disclosure provides a battery device comprising:

[0015] Secondary batteries;

[0016] A discharge cut-off circuit that cuts off the discharge of the secondary battery; and

[0017] A secondary battery protection integrated circuit, which protects the secondary battery.

[0018] The secondary battery protection integrated circuit has the following features:

[0019] A power terminal, which is connected to the positive terminal of the secondary battery;

[0020] A grounding terminal, which is connected to the negative terminal of the secondary battery; and

[0021] The control circuit controls the discharge cutoff circuit.

[0022] When the power supply voltage between the power supply terminal and the ground terminal is higher than a first determination voltage (which is higher than the second determination voltage), the control circuit performs a first action.

[0023] When the first condition is met—that the power supply voltage is lower than the first determined voltage during a first time period—the control circuit causes the discharge cut-off circuit to operate.

[0024] When the second condition is met—that the power supply voltage is lower than the second determined voltage during a second time period shorter than the first time—the control circuit causes the discharge cut-off circuit to operate.

[0025] According to this disclosure, secondary batteries can be adequately protected from over-discharge. Attached Figure Description

[0026] Figure 1 This is an example of a structural diagram of a system including the secondary battery protection integrated circuit of the first embodiment.

[0027] Figure 2 This is an example of a structural diagram of the discharge control circuit section of the secondary battery protection integrated circuit in the first embodiment.

[0028] Figure 3 This is an example of an operational diagram illustrating the discharge control of the secondary battery protection integrated circuit in the first embodiment.

[0029] Figure 4This is an example of the operation waveform diagram of the discharge control of the secondary battery protection integrated circuit in the first embodiment.

[0030] Figure 5 This is an example of a structural diagram of a system that includes the secondary battery protection integrated circuit of the second embodiment.

[0031] Figure 6 This is an example of a structural diagram of the discharge control circuit section of the secondary battery protection integrated circuit in the second embodiment.

[0032] Figure 7 This is an example of the operation waveform diagram of the discharge control of the secondary battery protection integrated circuit in the second embodiment.

[0033] Figure 8 This is an example of the operation waveform diagram of the discharge control of the secondary battery protection integrated circuit in the second embodiment.

[0034] Figure 9 This is an example of a structural diagram of a system that includes the secondary battery protection integrated circuit of the third embodiment.

[0035] Figure 10 This is an example of a structural diagram of the discharge control circuit section of the secondary battery protection integrated circuit in the third embodiment.

[0036] Figure 11 This is a diagram illustrating an example of a delay circuit.

[0037] Figure 12 This is an example of the operation waveform diagram of the discharge control of the secondary battery protection integrated circuit in the third embodiment.

[0038] Figure 13 This is an example of the operation waveform diagram of the discharge control of the secondary battery protection integrated circuit in the third embodiment.

[0039] Figure 14 This is an example of the operation waveform diagram of the discharge control of the secondary battery protection integrated circuit in the third embodiment.

[0040] Figure 15 This is an example of the operation waveform diagram of the discharge control of the secondary battery protection integrated circuit in the third embodiment.

[0041] Figure 16 This is an example of a structural diagram of a system including the secondary battery protection integrated circuit of the fourth embodiment.

[0042] Figure 17 This is an example of a structural diagram of the discharge control circuit section of the secondary battery protection integrated circuit according to the fourth embodiment.

[0043] Figure 18This is an example of the operation waveform diagram of the discharge control of the secondary battery protection integrated circuit in the fourth embodiment.

[0044] Figure 19 This is an example of the operation waveform diagram of the discharge control of the secondary battery protection integrated circuit in the fourth embodiment.

[0045] Figure 20 This is an example of a structural diagram of a system including the secondary battery protection integrated circuit of the fifth embodiment.

[0046] Figure 21 This is an example of a modified diagram showing the discharge control circuit section.

[0047] Figure 22 This is an example of a graph showing the relationship between the delay time tVdet and the remaining battery capacity and over-discharge detection voltage Vdet.

[0048] Figure 23 This is an example of a graph showing the relationship between over-discharge detection voltage and temperature in the fourth embodiment. Detailed Implementation

[0049] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings.

[0050] Figure 1 This is a circuit diagram illustrating an example of a system including the secondary battery protection integrated circuit of the first embodiment. Figure 1 The system 501 shown has a battery device 401 and electronic devices 300.

[0051] Electronic device 300 is a device connected to battery device 401. Electronic device 300 can be a charger for charging battery device 401, or a load that operates using power supplied from battery device 401. Specific examples of such loads include mobile phones, smartphones, tablets, and headphones. Electronic device 300 is not limited to these devices.

[0052] The battery device 401 can be externally mounted to the electronic device 300 or internally mounted therein. For example, the battery device 401 is a battery pack that is detachably mounted in the electronic device 300 and can supply power to the electronic device 300 while connected to it. The battery device 401 and the electronic device 300 are connected via... Figure 1 The multiple terminals shown (the positive power terminal (terminal P+) and the negative power terminal (terminal P-)) are interconnected. For example, when charging the secondary battery 210, terminals P+ and P- are electrically connected to the charger (electronic device 300).

[0053] The battery device 401 includes a secondary battery 210 and a battery protection device 601.

[0054] The secondary battery 210 is an example of a rechargeable battery. The secondary battery 210 supplies power to an electronic device 300 connected to terminals P+ and P-. The secondary battery 210 can be charged using a charger connected to terminals P+ and P-. Specific examples of the secondary battery 210 include lithium-ion batteries and lithium polymer batteries. The secondary battery 210 has a positive electrode 211 and a negative electrode 212.

[0055] Battery protection device 601 is an example of a secondary battery protection device that operates using a secondary battery 210 as a power source. Battery protection device 601 protects the secondary battery 210 from overcharging by controlling its charging and from over-discharging by controlling its discharging. Battery protection device 601 includes, for example, terminals P+, P-, B+, and B-, resistive elements R21 and R23, capacitor C21, power line 201, ground line 202, switching circuit 203, and protection IC (Integrated Circuit) 101.

[0056] The battery protection device 601 is, for example, a component having a substrate on which at least the protection IC 101 is mounted.

[0057] Terminal P+ is an example of a positive load terminal, connected to the power supply line of electronic device 300. Terminal P- is an example of a negative load terminal, connected to the ground line of electronic device 300. Terminal B+ is an example of a positive battery terminal, connected to the positive terminal 211 of secondary battery 210. Terminal B- is an example of a negative battery terminal, connected to the negative terminal 212 of secondary battery 210.

[0058] Terminals B+ and P+ are connected via power line 201, which serves as the positive current path. Power line 201 is the power path connecting terminals B+ and P+. Power line 201 functions as both the charging current path for the secondary battery 210 and the discharging current path for the secondary battery 210.

[0059] Terminals B- and P- are connected via a grounding wire 202, which serves as the negative current path. The grounding wire 202 is the power path connecting terminals B- and P-. The grounding wire 202 functions as both a charging path for the charging current of the secondary battery 210 and a discharging path for the discharging current of the secondary battery 210.

[0060] A switching circuit 203 is provided on the ground line 202 between terminal B- and terminal P-. The switching circuit 203 is, for example, a series circuit comprising a charging control transistor TR1 and a discharging control transistor TR2, connected in series. The charging control transistor TR1 is a semiconductor switching element that cuts off the charging path of the secondary battery 210. The discharging control transistor TR2 is a semiconductor switching element that cuts off the discharging path of the secondary battery 210.

[0061] exist Figure 1 In this case, the charging control transistor TR1 cuts off the grounding wire 202 through which the charging current of the secondary battery 210 flows, and the discharging control transistor TR2 cuts off the grounding wire 202 through which the discharging current of the secondary battery 210 flows. The charging control transistor TR1 and the discharging control transistor TR2 are switching elements that switch between turning the grounding wire 202 on and off, and are connected in series with the grounding wire 202. The charging control transistor TR1 and the discharging control transistor TR2 are, for example, N-channel MOSFETs (Metal Oxide Semiconductor Field Effect Transistors).

[0062] The charging control transistor TR1 has a parasitic diode D1 between its drain and source, which is forward-biased in a direction opposite to the charging current of the secondary battery 210. The charging control transistor TR1 is a switching element connected in series with the ground wire 202 in such a way that the forward direction of the parasitic diode D1 is in the same direction as the discharge current of the secondary battery 210.

[0063] The discharge control transistor TR2 has a parasitic diode D2 between its drain and source, which is forward-biased in a direction opposite to the discharge current of the secondary battery 210. The discharge control transistor TR2 is a switching element connected in series with the ground wire 202 in such a way that the forward direction of the parasitic diode D2 is in the same direction as the charging current of the secondary battery 210.

[0064] Protection IC101 is an example of a secondary battery protection integrated circuit used to protect a secondary battery. Protection IC101 operates by using the secondary battery 210 as a power source.

[0065] The protection IC 101 has the function of protecting the secondary battery 210 from over-discharge and other issues by controlling the switching circuit 203. For example, when the detection circuit 222 detects abnormal charging (e.g., overcharging, overcurrent in the charging direction (charging overcurrent), etc.), the protection IC 101 protects the secondary battery 210 from abnormal charging by turning off the charging control transistor TR1. On the other hand, when the detection circuit 222 detects abnormal discharging (e.g., over-discharge, overcurrent in the discharging direction (discharging overcurrent), etc.), the protection IC 101 protects the secondary battery 210 from the effects of abnormal discharging by turning off the discharging control transistor TR2.

[0066] The protection IC 101 includes, for example, a charging control terminal (terminal COUT), a discharging 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 connection terminals used to connect the internal circuitry of the protection IC 101 to the external environment of the protection IC 101.

[0067] Terminal COUT is connected to the gate (control electrode) of charging control transistor TR1, outputting a signal that turns charging control transistor TR1 on or off. Terminal DOUT is connected to the gate (control electrode) of discharging control transistor TR2, outputting a signal that turns discharging control transistor TR2 on or off.

[0068] Terminal VM is an example of a monitoring terminal used to monitor the potential of terminal P-, and is connected to terminal P-. Terminal VM is used, for example, to protect the control circuit 221 within IC 101 by monitoring whether an electronic device 300 or charger is connected. Terminal VM is connected to ground wire 202 via resistor element R23 between switching circuit 203 and terminal P-. Terminal VM is electrically connected to ground wire 202 on the side of switching circuit 203 opposite to that of secondary battery 210.

[0069] Terminal VM can also be used to detect overcurrent during charging or discharging through the secondary battery 210.

[0070] Terminal VDD is the power supply terminal protecting IC101, connected to the positive terminal 211 of the secondary battery 210 and the power line 201 via resistor R21. Terminal VSS is the ground terminal protecting IC101, connected to the negative terminal 212 of the secondary battery 210. Capacitor C21 is connected between terminals VDD and VSS. Terminal VSS is connected to ground line 202 between the switching circuit 203 and the negative terminal 212. In this example, terminal VSS is connected to ground line 202 between the discharge control transistor TR2 and the negative terminal 212.

[0071] The protection IC101 includes a detection circuit 222 and a control circuit 221.

[0072] The control circuit 221 includes a charging control circuit 221a for controlling the charging of the secondary battery 210. When the detection circuit 222 detects overcharging of the secondary battery 210 for a predetermined detection delay time tVdet1, the charging control circuit 221a outputs a signal (e.g., a low-level gate control signal) from terminal COUT to switch the charging control transistor TR1 from on to off. When the detection circuit 222 detects charging overcurrent of the secondary battery 210 for a predetermined detection delay time tVdet4, the charging control circuit 221a outputs a signal (e.g., a low-level gate control signal) from terminal COUT to switch the charging control transistor TR1 from on to off.

[0073] Control circuit 221 prevents current from flowing through ground wire 202 in the direction of charging secondary battery 210 by turning off charging control transistor TR1. Thus, charging of secondary battery 210 stops, and protection IC 101 protects secondary battery 210 from overcharging or charging overcurrent.

[0074] The control circuit 221 includes a discharge control circuit 221b for controlling the discharge of the secondary battery 210. When the discharge control circuit 221b detects over-discharge of the secondary battery 210 by the detection circuit 222 for a predetermined detection delay time tVdet2, it outputs a signal (e.g., a low-level gate control signal) from the terminal DOUT to switch the discharge control transistor TR2 from on to off. When the discharge control circuit 221b detects overcurrent in the secondary battery 210 by the detection circuit 222 for a predetermined detection delay time tVdet3, it outputs a signal (e.g., a low-level gate control signal) from the terminal DOUT to switch the discharge control transistor TR2 from on to off.

[0075] Control circuit 221 prevents current from flowing through ground wire 202 in the direction of discharging secondary battery 210 by turning off discharge control transistor TR2. Thus, discharging of secondary battery 210 stops, and protection IC 101 protects secondary battery 210 from over-discharge or overcurrent discharge.

[0076] The detection circuit 222 includes an over-discharge detection circuit that detects over-discharge of the secondary battery 210 by monitoring the power supply voltage Vdd between terminals VDD and VSS. The over-discharge detection circuit compares the power supply voltage Vdd with an over-discharge detection voltage Vdet2, and generates an over-discharge detection signal indicating that over-discharge of the secondary battery 210 has been detected when the power supply voltage Vdd is lower than the over-discharge detection voltage Vdet2.

[0077] exist Figure 1In the example shown, the over-discharge detection circuit includes a first over-discharge detection circuit 11 and a second over-discharge detection circuit 12. The first over-discharge detection circuit 11 compares the power supply voltage Vdd with a predetermined first over-discharge detection voltage Vdet2-1. When the power supply voltage Vdd is lower than Vdet2-1, it generates a first over-discharge detection signal S1 indicating that over-discharge of the secondary battery 210 has been detected. The second over-discharge detection circuit 12 compares the power supply voltage Vdd with a predetermined second over-discharge detection voltage Vdet2-2. When the power supply voltage Vdd is lower than Vdet2-2, it generates a second over-discharge detection signal S2 indicating that over-discharge of the secondary battery 210 has been detected.

[0078] Vdet2-1 is set higher than Vdet2-2. Vdet2-1 is an example of a first determination voltage. Vdet2-2 is an example of a second determination voltage lower than the first determination voltage. Vdet2-1 and Vdet2-2 are each preset to a voltage value determined by the respective adjustment state of a plurality of adjustment elements (not shown). The adjustment elements are fuse elements that can be cut off by a laser irradiated from outside the protection IC101.

[0079] The control circuit 221 includes a discharge control circuit 221b capable of controlling the discharge control transistor TR2, wherein the discharge control transistor TR2 is used to cut off the discharge of the secondary battery 210. The discharge control transistor TR2 is a discharge cut-off circuit that cuts off the discharge of the secondary battery 210.

[0080] When the power supply voltage Vdd is above Vdet2-1, the discharge control circuit 221b performs a first action. This first action, for example, allows the secondary battery 210 to discharge; specifically, it outputs a signal from terminal DOUT to turn on the discharge control transistor TR2. If the first over-discharge detection signal S1 is not detected, the discharge control circuit 221b determines that the power supply voltage Vdd is above Vdet2-1.

[0081] When the power supply voltage Vdd is lower than the first condition A1 (Vdet2-1) during a first time period, the discharge control circuit 221b activates the discharge control transistor TR2 to cut off the discharge of the secondary battery 210. For example, the discharge control circuit 221b determines that the first condition A1 is met when the first over-discharge detection signal S1 is detected by the delay circuit 21 for a predetermined detection delay time tVdet2-1. The detection delay time tVdet2-1 is an example of the first time period. When the first condition A1 is met, the discharge control circuit 221b outputs a signal from the terminal DOUT to turn off the discharge control transistor TR2 in order to stop the discharge of the secondary battery 210.

[0082] When the second condition A2 is met, and the power supply voltage Vdd is lower than Vdet2-2 during a second time period shorter than the first time, the discharge control circuit 221b activates the discharge control transistor TR2 to cut off the discharge of the secondary battery 210. For example, the discharge control circuit 221b determines that the second condition A2 is met when the second over-discharge detection signal S2 is detected by the delay circuit 22 for a predetermined detection delay time tVdet2-2. The detection delay time tVdet2-2 is an example of the second time. When the second condition A2 is met, the discharge control circuit 221b outputs a signal from the terminal DOUT to turn off the discharge control transistor TR2 in order to stop the discharge of the secondary battery 210.

[0083] Thus, according to the protection IC 101 of the first embodiment, when the power supply voltage Vdd is lower than Vdet2-1 for a detection delay time tVdet2-1, the discharge of the secondary battery 210 is cut off to protect the secondary battery 210 from over-discharge. On the other hand, when the power supply voltage Vdd is lower than Vdet2-2 (< Vdet2-1) for a detection delay time tVdet2-2 (< tVdet2-1), the discharge of the secondary battery 210 is cut off to protect the secondary battery 210 from over-discharge. Therefore, even if the voltage drop of the secondary battery 210 caused by discharge is small, if the power supply voltage Vdd is lower than Vdet2-1 for a detection delay time tVdet2-1, the discharge of the secondary battery 210 is cut off, thus appropriately protecting the secondary battery 210 from over-discharge. On the other hand, if the voltage drop of the secondary battery 210 caused by the discharge is large, the state in which the power supply voltage Vdd is lower than Vdet2-2 (< Vdet2-1) lasts for a shorter period of tVdet2-2 than tVdet2-1. In this case, the discharge of the secondary battery 210 is quickly cut off, thus properly protecting the secondary battery 210 from over-discharge.

[0084] Thus, the protection IC 101 in the first embodiment detects over-discharge by multiple determination voltages (Vdet2-1, Vdet2-2) and has multiple delay times (tVdet2-1, tVdet2-2) corresponding to these determination voltages. Vdet2-1 is set higher than Vdet2-2, and tVdet2-1 corresponding to Vdet2-1 is set longer than tVdet2-2 corresponding to Vdet2-2.

[0085] When the discharge current (load current) is small or the battery has sufficient charge, the voltage drop of the secondary battery 210 is small. Therefore, within the range where there are no abnormalities (damage, smoke, overheating, etc.) in the secondary battery 210 or electronic device 300, the judgment voltage can be set high and the delay time can be set long. Thus, when the discharge current (load current) is small or the battery has sufficient charge, even if the judgment voltage is set high and the delay time is set long, the impact of over-discharge judgment on discharge cutoff is relatively small. On the other hand, when the discharge current (load current) is large or the battery has insufficient charge, the voltage drop of the secondary battery 210 is large. Therefore, it is preferable to set the judgment voltage low and the delay time short. Thus, when the voltage drop of the secondary battery 210 is large, the secondary battery 210 is protected from over-discharge, and the discharge of the secondary battery 210 can be quickly cut off.

[0086] Thus, the protection IC101 and battery device 401 of the first embodiment have multiple different judgment voltages and multiple different delay times in order to implement the discharge cut-off operation against over-discharge, thereby properly protecting the secondary battery 210 from over-discharge.

[0087] In particular, when the secondary battery 210 is a lithium-ion battery using a silicon-based negative electrode, the protection IC 101 and battery device 401 of the first embodiment can appropriately protect the lithium-ion battery from over-discharge by having multiple different determination voltages and multiple different delay times. Compared with lithium-ion batteries using graphite-based negative electrodes, lithium-ion batteries using silicon-based negative electrodes have the advantage of high energy density, but have the disadvantage of being prone to degradation under over-discharge conditions. If the over-discharge detection voltage Vdet2 is set high for this degradation countermeasure, the sensitivity of the protection IC 101 in detecting over-discharge becomes high, and therefore the power supply to the electronic device 300 may become unstable due to excessive discharge cutoff. The protection IC 101 and battery device 401 of the first embodiment implement over-discharge detection and discharge current cutoff with multiple different sensitivities, thus ensuring the convenience of power supply to the electronic device 300 and suppressing the degradation of the lithium-ion battery.

[0088] Figure 2 This is a circuit diagram illustrating an example of the discharge control circuit section of the secondary battery protection integrated circuit according to the first embodiment. The detection circuit 222 includes a first over-discharge detection circuit 11 and a second over-discharge detection circuit 12.

[0089] The first over-discharge detection circuit 11 has a comparator that compares the power supply voltage Vdd with a predetermined first over-discharge detection voltage Vdet2-1, and outputs a first over-discharge detection signal S1 from node N1. When the power supply voltage Vdd is above the first over-discharge detection voltage Vdet2-1, the first over-discharge detection circuit 11 sets the level of the first over-discharge detection signal S1 to a low level; when the power supply voltage Vdd is below the first over-discharge detection voltage Vdet2-1, the first over-discharge detection signal S1 sets the level of the first over-discharge detection signal S1 to a high level. The second over-discharge detection circuit 12 has a comparator that compares the power supply voltage Vdd with a predetermined second over-discharge detection voltage Vdet2-2, and outputs a second over-discharge detection signal S2 from node N2. When the power supply voltage Vdd is above the second over-discharge detection voltage Vdet2-2, the second over-discharge detection circuit 12 sets the level of the second over-discharge detection signal S2 to a low level; when the power supply voltage Vdd is below the second over-discharge detection voltage Vdet2-2, the second over-discharge detection signal S2 sets the level of the second over-discharge detection signal S2 to a high level.

[0090] The discharge control circuit 221b includes delay circuits 21, 22, and 23, NOT gates 31 and 32, NOR gate 33 and OR gate 34, latch circuit 35, and NOT gate 36. NOT gate 31 generates a reset signal R1 that inverts the level of the first over-discharge detection signal S1. NOT gate 32 generates a reset signal R2 that inverts the level of the second over-discharge detection signal S2.

[0091] When the level of the first over-discharge detection signal S1 is low and the level of the reset signal R1 is high, the delay circuit 21 sets the level of node N3 to low (refer to...). Figure 3 T8 and Figure 4 State 1). In Figure 2 In the process, delay circuit 21 starts counting when the level of the first over-discharge detection signal S1 switches from low to high and the level of the reset signal R1 switches from high to low. After counting for a predetermined detection delay time tVdet2-1, delay circuit 21 switches the level of node N3 from low to high (refer to...). Figure 3 T9 and Figure 4 State 2).

[0092] exist Figure 2 In the process, when the level of node N3 switches from low to high, the level of the output node of OR gate 34 (the set terminal S of latch circuit 35) becomes high. Consequently, the over-discharge flag FDO output from the output terminal Q of latch circuit 35 switches from low to high, and therefore, NOT gate 36 switches the level of terminal DOUT from high to low. Thus, the discharge of secondary battery 210 is cut off by discharge control transistor TR2 (see reference). Figure 3 Action 1).

[0093] exist Figure 2 In the middle, when the level of the second over-discharge detection signal S2 is low and the level of the reset signal R2 is high, the delay circuit 22 sets the level of node N4 to low (refer to...). Figure 3 t4 and Figure 4 State 3). Figure 2 In the process, delay circuit 22 starts counting when the level of the second over-discharge detection signal S2 switches from low to high and the level of the reset signal R2 switches from high to low. After counting for a predetermined detection delay time tVdet2-2, delay circuit 22 switches the level of node N4 from low to high (refer to...). Figure 3 T5 and Figure 4 State 4).

[0094] exist Figure 2 In the process, when the level of node N4 switches from low to high, the level of the output node of OR gate 34 (the set terminal S of latch circuit 35) becomes high. Consequently, the over-discharge flag FDO output from the output terminal Q of latch circuit 35 switches from low to high, and therefore, NOT gate 36 switches the level of terminal DOUT from high to low. Thus, the discharge of secondary battery 210 is cut off by discharge control transistor TR2 (see reference). Figure 3 Action 2).

[0095] exist Figure 2 In the NOR gate 33, the output signal S3 is the NOR signal of the first over-discharge detection signal S1 and the second over-discharge detection signal S2. The reset signal R3 is the signal that inverts the level of signal S3.

[0096] When the level of signal S3 is low and the level of reset signal R3 is high, delay circuit 23 sets the level of node N6 to low. Figure 3(t6, t10). Additionally, the signal S3 is low and the reset signal R3 is high when node N1 or node N2 is low, and the power supply voltage Vdd is lower than Vdet2-1 (e.g., 2.8V). When the signal S3 switches from low to high and the reset signal R3 switches from high to low, the delay circuit 23 starts counting. Counting begins when node N1 and node N2 are low, and the power supply voltage Vdd is above Vdet2-1 (e.g., 2.8V). After counting a predetermined detection delay time tVrel2, the delay circuit 23 switches the level of node N6 (the reset terminal R of the latch circuit 35) from low to high. As a result, the over-discharge flag FDO output from the output terminal Q of the latch circuit 35 switches from high to low, and therefore, the NOT gate 36 switches the level of terminal DOUT from low to high. Figure 3 (t6-1, t10-1). Therefore, the secondary battery 210 recovers from the over-discharge state, and the discharge of the secondary battery 210 is allowed by the conduction of the discharge control transistor TR2 (refer to...). Figure 3 Over-discharge recovery).

[0097] Furthermore, if the power supply voltage Vdd becomes smaller than the over-discharge detection voltage Vdet2-1, but the time it takes for the power supply voltage Vdd to become smaller than the over-discharge detection voltage Vdet2-1 is shorter than the detection delay time tVdet2-1, the discharge control circuit 221b will not turn off the discharge control transistor TR2. Figure 3 (t1 to t2). Similarly, if the power supply voltage Vdd becomes smaller than the over-discharge detection voltage Vdet2-2, but the time it takes for the power supply voltage Vdd to become smaller than the over-discharge detection voltage Vdet2-2 is shorter than the detection delay time tVdet2-2, the discharge control circuit 221b does not turn off the discharge control transistor TR2. As a result, it is possible to prevent the discharge control transistor TR2 from being turned off due to noise, etc.

[0098] Figure 5 This is a circuit diagram illustrating an example of a system incorporating the secondary battery protection integrated circuit of the second embodiment. In the second embodiment, descriptions of the same structure, function, and effects as in the first embodiment are omitted by referring to the above description. The difference between the second embodiment and the first embodiment is that it further includes input terminals SL and SEL.

[0099] Figure 5The system 502 shown includes a battery device 402 and an electronic device 300. The battery device 402 includes a secondary battery 210 and a battery protection device 602. The battery protection device 602 is, for example, a component having a substrate on which at least a protection IC 102 is mounted. The battery device 402 has an input terminal SL. The protection IC 102 has an input terminal SEL connected to the input terminal SL.

[0100] Input terminals SL and SEL are input terminals for receiving information from external devices such as electronic device 300. During the period when the discharge control circuit 221b receives predetermined first information SI1 from the external device via input terminal SEL, it controls the discharge control transistor TR2 under a first condition A1. During the period when the discharge control circuit 221b receives second information SI2, which is different from the first information SI1, from the external device via input terminal SEL, it controls the discharge control transistor TR2 under a second condition A2. Therefore, the discharge control circuit 221b can switch the over-discharge detection voltage Vdet2 and the detection delay time tVdet2 to values ​​corresponding to the different information input from the external device to input terminal SEL.

[0101] Figure 6 This is a circuit diagram illustrating an example of the discharge control circuit section of the secondary battery protection integrated circuit according to the second embodiment. The detection circuit 222 includes a first over-discharge detection circuit 11 and a second over-discharge detection circuit 12. The discharge control circuit 221b includes delay circuits 21, 22, and 23, logic gates 41, 42, 43, and 44, a NOR gate 33, an OR gate 34, a latch circuit 35, and a NOT gate 36.

[0102] Logic gate 41 outputs the logic product of the level of the information input from input terminal SEL (inverted) and the level of node N1, which is the first over-discharge detection signal S1. Logic gate 42 outputs the NAND of the level of the information input from input terminal SEL and the level of node N1, which is the reset signal R1. Logic gate 43 outputs the logic product of the level of the information input from input terminal SEL and the level of node N2, which is the second over-discharge detection signal S2. Logic gate 44 outputs the NAND of the level of the information input from input terminal SEL and the level of node N2, which is the reset signal R2. Delay circuits 21, 22, and 23 operate in the same way as described above.

[0103] Input either first information SI1 or second information SI2 to the input terminal SEL as information received from an external device. For example, first information SI1 indicates that electronic device 300 is in sleep mode, and second information SI2 indicates that electronic device 300 is in operating mode. Sleep mode indicates that the power consumption of electronic device 300 is lower than that of operating mode.

[0104] In the operating state, the discharge current (load current) is relatively large, resulting in a large voltage drop in the secondary battery 210. Therefore, it is preferable to set the determination voltage low and the delay time short. Thus, during the period when the second information SI2, indicating the operating state, is input to the input terminal SEL, the discharge control circuit 221b controls the discharge control transistor TR2 according to the second condition A2. In this case, similar to the first embodiment, when the state where the power supply voltage Vdd is lower than Vdet2-2 (< Vdet2-1) continues for the detection delay time tVdet2-2 (< tVdet2-1), the delay circuit 22 cuts off the discharge of the secondary battery 210 (see reference). Figure 7 Therefore, the discharge of the secondary battery 210 is quickly cut off, thus properly protecting the secondary battery 210 from over-discharge.

[0105] On the other hand, in the sleep state, the discharge current (load current) is relatively small, so the voltage drop of the secondary battery 210 is small. Therefore, within the range where there are no abnormalities (damage, smoke, overheating, etc.) in the secondary battery 210 or electronic device 300, the determination voltage can be set high and the delay time can be set long. Therefore, during the period when the first information SI1 indicating the sleep state is input to the input terminal SEL, the discharge control circuit 221b controls the discharge control transistor TR2 according to the first condition A1. In this case, similarly to the first embodiment, when the state of the power supply voltage Vdd being lower than Vdet2-1 continues for the detection delay time tVdet2-1, the delay circuit 21 cuts off the discharge of the secondary battery 210 (see reference). Figure 8 Therefore, the secondary battery 210 can be properly protected from over-discharge.

[0106] Furthermore, the first information SI1 and the second information SI2 are not limited to the operation information of the electronic device 300 such as sleep state and working state, but can also be the remaining information such as the SOC (State of Charge) of the secondary battery 210. The remaining information such as SOC is calculated by the remaining information IC, the electronic device 300, etc. For example, the first information SI1 indicates that the SOC of the secondary battery 210 is a first SOC state, and the second information SI2 indicates that the SOC of the secondary battery 210 is a second SOC state lower than the first SOC state. For example, when the threshold VSOC is 10%, the first information SI1 indicates a state where the SOC is above 0% and below 10% (first SOC state), and the second information SI2 indicates a state where the SOC is above 10% and below 100% (second SOC state).

[0107] Figure 9This is a circuit diagram illustrating an example of a system incorporating the secondary battery protection integrated circuit of the third embodiment. In the third embodiment, descriptions of the same structure, function, and effects as in the above-described embodiment are omitted by referring to the above description. The difference between the third embodiment and the first embodiment is that it further includes a low-voltage detection circuit 50.

[0108] Figure 9 The system 503 shown includes a battery device 403 and an electronic device 300. The battery device 403 includes a secondary battery 210 and a battery protection device 603. The battery protection device 603 is, for example, a component having a substrate on which at least a protection IC 103 is mounted.

[0109] Protection IC 103 triggers when the power supply voltage Vdd becomes the determination voltage Vsoc (> over-discharge detection voltage Vdet2). Based on information detected internally by protection IC 103, it selects the over-discharge detection specification (over-discharge detection voltage Vdet2 and detection delay time tVdet2). Discharge control circuit 221b switches the over-discharge detection specification (over-discharge detection voltage Vdet2 and detection delay time tVdet2) according to the state of the power supply voltage Vdd before the detection of over-discharge detection voltage Vdet2. By using information about the power supply voltage Vdd before the detection of over-discharge in the selection of the over-discharge detection specification, discharge control circuit 221b can more appropriately select the over-discharge detection specification.

[0110] The low-voltage detection circuit 50 compares the power supply voltage Vdd with a predetermined judgment voltage Vsoc. When the power supply voltage Vdd is lower than the judgment voltage Vsoc, it generates a low-voltage detection signal Vo indicating that a low power supply voltage Vdd below the predetermined voltage value has been detected. The judgment voltage Vsoc is set higher than Vdet2-1. The judgment voltage Vsoc is an example of a third judgment voltage. Based on a pre-obtained relationship between SOC and battery voltage, the judgment voltage Vsoc is preset to a predetermined voltage value through the fine-tuning states of multiple fine-tuning elements (not shown).

[0111] Figure 22This diagram illustrates an example of the relationship between the detection delay time tVdet2 and the remaining battery capacity and over-discharge detection voltage Vdet2. After the power supply voltage Vdd drops below the judgment voltage Vsoc, the discharge control circuit 221b determines whether the power supply voltage Vdd is less than Vdet2-2 after a delay time tVsoc. The delay time tVsoc is an example of a third time. When the power supply voltage Vdd is less than Vdet2-2, the discharge control circuit 221b activates the discharge control transistor TR2 after a time tVdet2-2b, which is shorter than the detection delay time tVdet2-2. tVdet2-2b is an example of a fourth time, shorter than the second time mentioned above.

[0112] After the power supply voltage Vdd drops below the determination voltage Vsoc, the discharge control circuit 221b determines whether the power supply voltage Vdd is less than Vdet2-1 and greater than Vdet2-2 after a delay time tVsoc. If the power supply voltage Vdd is less than Vdet2-1 and greater than Vdet2-2, the discharge control circuit 221b activates the discharge control transistor TR2 after a delay time tVdet2-1b shorter than the detection delay time tVdet2-1. tVdet2-1b is an example of a fifth time shorter than the first time mentioned above.

[0113] The discharge control circuit 221b determines whether the power supply voltage Vdd is less than Vdet2-2 before a delay time tVsoc has elapsed after the power supply voltage Vdd drops below the determination voltage Vsoc. The delay time tVsoc is an example of a third time. If the power supply voltage Vdd is less than Vdet2-2, the discharge control circuit 221b activates the discharge control transistor TR2 after the detection delay time tVdet2-2 (the second time).

[0114] After the power supply voltage Vdd drops below the judgment voltage Vsoc, before a delay time tVsoc elapses, the discharge control circuit 221b determines whether the power supply voltage Vdd is less than Vdet2-1 and greater than Vdet2-2. If the power supply voltage Vdd is less than Vdet2-1 and greater than Vdet2-2, the discharge control circuit 221b activates the discharge control transistor TR2 after the detection delay time tVdet2-1 (the first time).

[0115] Figure 10This is a circuit diagram illustrating an example of the discharge control circuit section of the secondary battery protection integrated circuit according to the third embodiment. The low-voltage detection circuit 50 includes a comparator that compares the power supply voltage Vdd with a predetermined determination voltage Vsoc, and outputs a low-voltage detection signal Vo. When the power supply voltage Vdd is above the determination voltage Vsoc, the low-voltage detection circuit 50 sets the level of the low-voltage detection signal Vo to a high level; when the power supply voltage Vdd is below the determination voltage Vsoc, the low-voltage detection signal Vo is set to a low level.

[0116] OR gate 15 outputs a signal that is the logical sum (OR) of the first over-discharge detection signal S1 and the second over-discharge detection signal S2. The pulse generation circuit 16 generates a single-trigger pulse Φ of a predetermined pulse width when both the first over-discharge detection signal S1 and the second over-discharge detection signal S2 are detected to be high.

[0117] After detecting that the power supply voltage Vdd is less than the judgment voltage Vsoc, delay circuit 13 switches the delayed signal De from high to low after a predetermined delay time tVsoc. Delay circuit 13 is the circuit that generates the delay time tVsoc. Figure 11 As shown, the delay circuit 13 can also be a shift register 13A formed by connecting flip-flops in series.

[0118] exist Figure 10 In this circuit, the delayed signal De is input to the data input terminal of flip-flop 14. Flip-flop 14 has a set terminal S for inputting a low-voltage detection signal Vo and a clock input terminal for inputting a single trigger pulse Φ. Flip-flop 14 sets the level of the timing-delayed signal De, which has been input with the single trigger pulse Φ, to the level of the low-voltage flag Nsoc. When the power supply voltage Vdd is higher than the determination voltage Vsoc, the low-voltage flag Nsoc becomes high; when the power supply voltage Vdd is lower than the determination voltage Vsoc, the low-voltage flag Nsoc becomes low. The operation of delay circuits 21, 22, and 23 is the same as described above.

[0119] When the level of the first over-discharge detection signal S1 is low and the level of the reset signal R1 is high, the delay circuit 21 sets the levels of nodes N3a and N3b to low. When the level of the first over-discharge detection signal S1 switches from low to high and the level of the reset signal R1 switches from high to low, the delay circuit 21 starts counting. After counting for a predetermined detection delay time tVdet2-1, the delay circuit 21 switches the level of node N3a from low to high. After counting for a predetermined detection delay time tVdet2-1b, the delay circuit 21 switches the level of node N3b from low to high. tVdet2-1b is a time shorter than tVdet2-1.

[0120] When the second over-discharge detection signal S2 is low and the reset signal R2 is high, the delay circuit 22 sets the levels of nodes N4a and N4b to low. When the level of the second over-discharge detection signal S2 switches from low to high and the level of the reset signal R2 switches from high to low, the delay circuit 22 begins counting. After counting for a predetermined detection delay time tVdet2-2, the delay circuit 22 switches the level of node N4a from low to high. After counting for a predetermined detection delay time tVdet2-2b, the delay circuit 22 switches the level of node N4b from low to high. tVdet2-2b is a time shorter than tVdet2-2.

[0121] When the low-voltage flag Nsoc is high, logic gate 51 selects tVdet2-1 generated by delay circuit 21 as the detection delay time tVdet2. Logic gate 51 outputs the logical product of the signal N3a and the signal Nsoc. When the low-voltage flag Nsoc is low, logic gate 52 selects tVdet2-1b generated by delay circuit 21 as the detection delay time tVdet2. Logic gate 52 outputs the logical product of the signal N3a and the inverted signal of Nsoc.

[0122] When the low-voltage flag Nsoc is high, logic gate 54 selects tVdet2-2 generated by delay circuit 22 as the detection delay time tVdet2. Logic gate 54 outputs the logical product of the signal N4a and the signal Nsoc. When the low-voltage flag Nsoc is low, logic gate 55 selects tVdet2-2b generated by delay circuit 22 as the detection delay time tVdet2. Logic gate 55 outputs the logical product of the signal N4b and the signal Nsoc.

[0123] OR gate 53 outputs the logical sum (OR) of the output signals of logic gate 51 and logic gate 52. OR gate 56 outputs the logical sum of the output signals of logic gate 54 and logic gate 55. OR gate 34 outputs the logical sum of the output signals of OR gate 53 and OR gate 56. Other circuit sections are the same as described above.

[0124] Figure 12 This is an example of the operation waveform diagram of the discharge control of the secondary battery protection integrated circuit in the third embodiment. Figure 12This example illustrates a scenario where the secondary battery 210 has a large battery capacity (the power supply voltage Vdd is above Vsoc before over-discharge is detected) and a small load current. When the load 300 is connected to the system 503, the power supply voltage Vdd begins to decrease. Due to the large battery capacity and small load current of the secondary battery 210, the power supply voltage Vdd decreases to below Vdet2-1, but not to Vdet2-2. As the power supply voltage Vdd decreases below the judgment voltage Vsoc, the low-voltage detection signal Vo decreases from a high level to a low level. After a predetermined delay time tVsoc, the delayed signal De switches from a high level to a low level.

[0125] When the power supply voltage Vdd drops below the judgment voltage Vsoc, and before the delay time tVsoc, the power supply voltage Vdd drops below Vdet2-1, a single trigger pulse Φ is generated to set the low voltage flag Nsoc to a high level. Therefore, the discharge control circuit 221b activates the discharge control transistor TR2 after the detection delay time tVdet2-1 generated by the delay circuit 21. As a result, the discharge of the secondary battery 210 is cut off (see reference). Figure 12 Therefore, it can properly protect the secondary battery 210 from over-discharge.

[0126] Figure 13 This is an example of the operation waveform diagram of the discharge control of the secondary battery protection integrated circuit in the third embodiment. Figure 13 This example illustrates a scenario where the secondary battery 210 has a small remaining charge (the power supply voltage Vdd before over-discharge is detected is less than Vsoc) and a small load current. When the load 300 is connected to the system 503, the power supply voltage Vdd begins to decrease. Due to the small remaining charge and small load current of the secondary battery 210, the power supply voltage Vdd decreases below Vdet2-1, but not below Vdet2-2. As the power supply voltage Vdd decreases below the judgment voltage Vsoc, the low-voltage detection signal Vo decreases from a high level to a low level. After a predetermined delay time tVsoc, the delayed signal De switches from a high level to a low level.

[0127] When the power supply voltage Vdd drops below the judgment voltage Vsoc, and after a delay time tVsoc, the power supply voltage Vdd drops below Vdet2-1, a single trigger pulse Φ is generated to set the low voltage flag Nsoc to a high level. Therefore, the discharge control circuit 221b activates the discharge control transistor TR2 after a detection delay time tVdet2-1b (<tVdet2-1) generated by the delay circuit 21. As a result, the discharge of the secondary battery 210 is rapidly cut off (see reference). Figure 13 Therefore, it can properly protect the secondary battery 210 from over-discharge.

[0128] Figure 14 This is an example of the operation waveform diagram of the discharge control of the secondary battery protection integrated circuit in the third embodiment. Figure 14 This example illustrates a scenario where the secondary battery 210 has a large battery capacity (the power supply voltage Vdd is above Vsoc before over-discharge is detected) and a large load current. When the load 300 is connected to the system 503, the power supply voltage Vdd begins to decrease. Due to the large battery capacity and large load current of the secondary battery 210, the power supply voltage Vdd decreases to below Vdet2-2, which is lower than Vdet2-1. As the power supply voltage Vdd decreases below the judgment voltage Vsoc, the low-voltage detection signal Vo decreases from a high level to a low level. After a predetermined delay time tVsoc, the delayed signal De switches from a high level to a low level.

[0129] When the power supply voltage Vdd drops below the judgment voltage Vsoc, and before the delay time tVsoc, the power supply voltage Vdd drops below Vdet2-2, a single trigger pulse Φ is generated to set the low voltage flag Nsoc to a high level. Therefore, the discharge control circuit 221b activates the discharge control transistor TR2 after the detection delay time tVdet2-2 generated by the delay circuit 22. As a result, the discharge of the secondary battery 210 is cut off (see reference). Figure 14 Therefore, it can properly protect the secondary battery 210 from over-discharge. tVdet2-2 is less than tVdet2-1.

[0130] Figure 15 This is an example of the operation waveform diagram of the discharge control of the secondary battery protection integrated circuit in the third embodiment. Figure 15 This example illustrates a scenario where the secondary battery 210 has a small remaining charge (the power supply voltage Vdd before over-discharge is detected is less than Vsoc) and a large load current. When the load 300 is connected to the system 503, the power supply voltage Vdd begins to decrease. Due to the small remaining charge of the secondary battery 210 and the large load current, the power supply voltage Vdd decreases to below Vdet2-2, which is lower than Vdet2-1. As the power supply voltage Vdd decreases below the judgment voltage Vsoc, the low-voltage detection signal Vo decreases from a high level to a low level. After a predetermined delay time tVsoc, the delayed signal De switches from a high level to a low level.

[0131] When the power supply voltage Vdd drops below the judgment voltage Vsoc, and after a delay time tVsoc, the power supply voltage Vdd drops below Vdet2-2, a single trigger pulse Φ is generated to set the low voltage flag Nsoc to a high level. Therefore, after a detection delay time tVdet2-2b (<tVdet2-2) generated by the delay circuit 22, the discharge control circuit 221b activates the discharge control transistor TR2. As a result, the discharge of the secondary battery 210 is rapidly cut off (see reference). Figure 15 Therefore, it can properly protect the secondary battery 210 from over-discharge. tVdet2-2b is shorter than tVdet2-1b.

[0132] Figure 16 This is a circuit diagram illustrating an example of a system incorporating the secondary battery protection integrated circuit of the fourth embodiment. In the fourth embodiment, descriptions of the same structure, function, and effects as in the above-described embodiment are omitted by referring to the above description. The fourth embodiment differs from the second embodiment in that it further includes a temperature sensor 301.

[0133] Figure 16 The system 504 shown includes a battery device 404 and an electronic device 300. The battery device 404 includes a secondary battery 210 and a battery protection device 604. The battery protection device 604 is, for example, a component having a substrate on which at least a protection IC 104 is mounted. The battery device 404 has an input terminal SL. The protection IC 104 has an input terminal SEL connected to the input terminal SL.

[0134] Temperature sensor 301 detects the temperature (or ambient temperature) of the secondary battery 210. Temperature sensor 301 is located in the battery assembly 404. Temperature sensor 301 can be located inside or outside the protection IC 104. Temperature sensor 301 is, for example, a thermistor. Protection IC 104 has a terminal TS connected to temperature sensor 301. Protection IC 104 or electronic device 300 obtains the temperature detected by temperature sensor 301 from terminal TS.

[0135] The protection IC103 selects the over-discharge detection specification (over-discharge detection voltage Vdet2 and detection delay time tVdet2) based on the temperature information detected by the temperature sensor 301. By using temperature information in the selection of the over-discharge detection specification, the discharge control circuit 221b can more appropriately select the over-discharge detection specification.

[0136] Figure 23 This is an example of a graph showing the relationship between over-discharge detection voltage and temperature. For example, as shown... Figure 23As shown, when the temperature detected by the temperature sensor 301 is above the first temperature T1 and below the second temperature T2 (e.g., normal temperature state), the discharge control circuit 221b activates the discharge control transistor TR2 under the second condition A2. When the temperature detected by the temperature sensor 301 is lower than the first temperature T1 or higher than the second temperature T2 (e.g., high temperature state or low temperature state), the discharge control circuit 221b activates the discharge control transistor TR2 under the first condition A1. Thus, the discharge control circuit 221b can switch the over-discharge detection voltage Vdet2 and the detection delay time tVdet2 to values ​​corresponding to the temperature based on the temperature difference detected by the temperature sensor 301.

[0137] Figure 17 This is a circuit diagram illustrating an example of the discharge control circuit section of the secondary battery protection integrated circuit according to the fourth embodiment. The discharge control circuit 221b includes delay circuits 21, 22, and 23, logic gates 41, 42, 43, and 44, NOR gate 33, OR gate 34, latch circuit 35, and NOT gate 36. The operation of these circuits is the same as in the second embodiment.

[0138] Temperature information detected by temperature sensor 301 can be input to input terminal SEL as information received from an external device. Alternatively, temperature information detected by temperature sensor 301 can be input to temperature flag 24 on discharge control circuit 221b.

[0139] For example, while the discharge control circuit 221b is inputting temperature information at a low level indicating a normal temperature state to the input terminal SEL or the temperature flag 24, it controls the discharge control transistor TR2 under the second condition A2. In this case, similarly to the first embodiment, when the state where the power supply voltage Vdd is lower than Vdet2-2 (< Vdet2-1) persists for a detection delay time tVdet2-2 (< tVdet2-1), the delay circuit 22 cuts off the discharge of the secondary battery 210 (see reference). Figure 18 Therefore, the discharge of the secondary battery 210 is quickly cut off, thus properly protecting the secondary battery 210 from over-discharge.

[0140] On the other hand, Figure 17 In this process, while the discharge control circuit 221b is inputting high-level temperature information indicating a high-temperature or low-temperature state to the input terminal SEL or the temperature flag 24, it controls the discharge control transistor TR2 under the first condition A1. In this case, similarly to the first embodiment, when the power supply voltage Vdd is lower than Vdet2-1 for a detection delay time tVdet2-1, the delay circuit 21 cuts off the discharge of the secondary battery 210 (see reference). Figure 19 Therefore, the secondary battery 210 can be properly protected from over-discharge.

[0141] Figure 20 This is a circuit diagram illustrating an example of a system incorporating the secondary battery protection integrated circuit of the fifth embodiment. In the fifth embodiment, descriptions of the same structure, function, and effects as in the previous embodiments are omitted by referring to the above description. The difference between the fifth embodiment and the first embodiment is that the switching circuit 203 is provided on the power line 201 on the high side. As a variation of the fifth embodiment, a structure combining the structures of the second, third, or fourth embodiments can also be considered.

[0142] Figure 20 The system 505 shown includes a battery device 405 and an electronic device 300. The battery device 405 includes a secondary battery 210 and a battery protection device 605. The battery protection device 605 is, for example, a component having a substrate on which at least a protection IC 105 is mounted. Terminal VP has the same function as terminal VM in the first embodiment.

[0143] Figure 21 This is an example of a modified discharge control circuit. The discharge control circuit 221b of the protection IC has a node NA that receives information from the aforementioned input terminal SEL or temperature flag 24. The discharge control circuit 221b can change the voltage division ratio of the power supply voltage Vdd, determined by the resistors R1 and R2 of the detection circuit 222, or change the length of the detection delay time tVdet2 generated by the delay circuit 20, depending on the state of node NA. By changing the voltage division ratio of the power supply voltage Vdd, determined by the resistors R1 and R2 of the detection circuit 222, the discharge control circuit 221b switches the over-discharge detection voltage Vdet2 to different values ​​based on the state of node NA. This allows for miniaturization of the circuit used to change the over-discharge detection voltage Vdet2 (=(R1+R2)×(R1 / Vref)).

[0144] As described above, the embodiments have been explained, but these embodiments are provided as examples, and the present invention is not limited to these embodiments. The embodiments described above can be implemented in various other ways, and various combinations, omissions, substitutions, modifications, etc., can be made without departing from the spirit of the invention. These embodiments and their variations are included within the scope and spirit of the invention, and are also included within the scope of the invention and its equivalents as described in the patent protection scope.

[0145] For example, the configuration positions of the charging control transistor TR1 and the discharging control transistor TR2 can also be interchanged relative to their positions shown in the figure. The switching circuit 203 can also be built into the protection IC.

[0146] Explanation of reference numerals in the attached figures

[0147] 101, 102, 103, 104, 105 Protection ICs

[0148] 201 power cord

[0149] 202 grounding wire

[0150] 203 Switching Circuit

[0151] 210 secondary battery

[0152] 211 positive electrode

[0153] 212 negative electrode

[0154] 221 control circuit

[0155] 222 Detection Circuit

[0156] 300 electronic devices

[0157] Battery devices 401, 402, 403, 404, and 405

[0158] Systems 501, 502, 503, 504, and 505

[0159] Battery protection devices 601, 602, 603, 604, and 605

[0160] TR1 charging control transistor

[0161] TR2 discharge control transistor.

Claims

1. A secondary battery protection integrated circuit, used to protect a secondary battery, characterized in that, The secondary battery protection integrated circuit has the following features: A power terminal that can be connected to the positive terminal of the secondary battery; A grounding terminal, which can be connected to the negative terminal of the secondary battery; and A control circuit that controls a discharge cutoff circuit used to cut off the discharge of the secondary battery. When the power supply voltage between the power supply terminal and the ground terminal is higher than a first determination voltage (which is higher than the second determination voltage), the control circuit performs a first action. When the first condition is met—that the power supply voltage is lower than the first determined voltage during a first time period—the control circuit causes the discharge cut-off circuit to operate. When the second condition is met—that the power supply voltage is lower than the second determined voltage during a second time period shorter than the first time—the control circuit causes the discharge cut-off circuit to operate.

2. The secondary battery protection integrated circuit according to claim 1, characterized in that, The secondary battery protection integrated circuit also has an input terminal for receiving information from external devices. The control circuit controls the discharge cutoff circuit under the first condition while receiving first information from the external device via the input terminal, and controls the discharge cutoff circuit under the second condition while receiving second information different from the first information from the external device via the input terminal.

3. The secondary battery protection integrated circuit according to claim 1, characterized in that, If, after a third time has elapsed following a drop in the power supply voltage to below a third determination voltage that is higher than the first determination voltage, and the power supply voltage becomes lower than the second determination voltage, the control circuit activates the discharge cut-off circuit after a fourth time elapsed that is shorter than the second time.

4. The secondary battery protection integrated circuit according to claim 3, characterized in that, If, after the power supply voltage drops below the third determination voltage and a third time has elapsed, the power supply voltage becomes less than the first determination voltage but greater than the second determination voltage, the control circuit activates the discharge cut-off circuit after a fifth time elapsed, which is shorter than the first time.

5. The secondary battery protection integrated circuit according to claim 1, characterized in that, When the temperature detected by the temperature sensor is above the first temperature and below the second temperature, the control circuit activates the discharge cut-off circuit according to the second condition; when the temperature detected by the temperature sensor is lower than the first temperature or higher than the second temperature, the control circuit activates the discharge cut-off circuit according to the first condition.

6. The secondary battery protection integrated circuit according to claim 2, characterized in that, The first information indicates that the electronic device receiving power from the secondary battery is in a sleep state, and the second information indicates that the electronic device is in a working state.

7. The secondary battery protection integrated circuit according to claim 2, characterized in that, The first information indicates that the SOC of the secondary battery is a first SOC state, and the second information indicates that the SOC of the secondary battery is a second SOC state that is lower than the first SOC state.

8. A battery device, characterized in that, The battery device includes: Secondary batteries; A discharge cut-off circuit that cuts off the discharge of the secondary battery; and A secondary battery protection integrated circuit, which protects the secondary battery. The secondary battery protection integrated circuit has the following features: A power terminal, which is connected to the positive terminal of the secondary battery; A grounding terminal, which is connected to the negative terminal of the secondary battery; and The control circuit controls the discharge cutoff circuit. When the power supply voltage between the power supply terminal and the ground terminal is higher than a first determination voltage (which is higher than the second determination voltage), the control circuit performs a first action. When the first condition is met—that the power supply voltage is lower than the first determined voltage during a first time period—the control circuit causes the discharge cut-off circuit to operate. When the second condition is met—that the power supply voltage is lower than the second determined voltage during a second time period shorter than the first time—the control circuit causes the discharge cut-off circuit to operate.

9. The battery device according to claim 8, characterized in that, The secondary battery is a lithium-ion battery using a silicon-based load.

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