Battery protection circuit and system

Abstract

An embodiment of the present invention discloses a battery protection circuit and system. The battery protection circuit includes a battery module, a switch module, a current limiting module, and a protection controller. The protection controller includes a logic control module, a driving module, an anti-backflow module, and a matching module. The first end of the driving module is connected to the first end of the protection controller, the second end of the driving module is connected to the third end of the protection controller, and the control end of the driving module is connected to the logic control module. The anti-backflow module is connected between the second end of the protection controller and the second end of the driving module, and the anti-backflow module is used to prevent the current at the fourth end of the protection controller from flowing into the second end of the battery module after the switch module is turned off. The matching module is connected between the third end and the fourth end of the protection controller, and the matching module is used to match the potential between the third end and the fourth end of the protection controller. The technical solution provided by the embodiment of the present invention can improve the reliability of the battery protection circuit.

Description

Technical Field

[0001] The embodiments of the present invention relate to the technical field of batteries, and in particular, to a battery protection circuit and system. Background Art

[0002] With the continuous development of electronic technology, mobile devices have been widely popularized, and mobile devices usually use lithium batteries as power supplies.

[0003] Currently, in order to protect the charging and discharging safety of lithium batteries, the lithium battery body and the protection circuit are usually combined for application. In the process of the gradual miniaturization of devices, the protection circuit also needs to be miniaturized to meet the usage requirements. However, with the increasing integration of the protection circuit, the problem of unstable protection circuit has emerged, reducing the reliability of the protection circuit. Summary of the Invention

[0004] The embodiments of the present invention provide a battery protection circuit and system to improve the reliability of the battery protection circuit.

[0005] According to one aspect of the present invention, a battery protection circuit is provided, including: a battery module, a switch module, a current limiting module, and a protection controller. The first end of the battery module is connected to the first end of the battery protection circuit and the first end of the protection controller. The second end of the battery module is connected to the first end of the switch module and the second end of the protection controller. The second end of the switch module is connected to the second end of the battery protection circuit. The third end of the protection controller is connected to the control end of the switch module. The fourth end of the protection controller is connected to the first end of the current limiting module. The second end of the current limiting module is connected to the second end of the battery protection circuit;

[0006] The protection controller includes a logic control module, a drive module, an anti-backflow module, and a matching module;

[0007] The first end of the drive module is connected to the first end of the protection controller. The second end of the drive module is connected to the third end of the protection controller. The control end of the drive module is connected to the logic control module. The drive module is used to control whether the switch module is turned on or off in response to the signal output by the logic control module;

[0008] The anti-backflow module is connected between the second end of the protection controller and the second end of the drive module. The anti-backflow module is used to prevent the current at the fourth end of the protection controller from flowing into the second end of the battery module after the switch module is turned off. The matching module is connected between the third end and the fourth end of the protection controller. The matching module is used to match the potential between the third end and the fourth end of the protection controller.

[0009] Optionally, the anti-backflow module includes a diode, the negative electrode of the diode is connected to the second end of the protection controller, and the positive electrode of the diode is connected to the second end of the drive module.

[0010] Optionally, the protection controller further includes a discharge module. The first end of the discharge module is connected to the first end of the anti-backflow module, the second end of the anti-backflow module is connected to the second end of the drive module, and the second end of the discharge module is connected to the second end of the protection controller. The discharge module is configured to discharge the control end of the switch module when the voltage at the control end of the switch module is greater than a preset voltage during the turn-off process of the switch module;

[0011] The discharge module is further configured to remain off when the voltage at the control end of the switch module is less than or equal to the preset voltage.

[0012] Optionally, the conduction ability of the discharge module is greater than that of the matching module.

[0013] Optionally, the discharge module includes a voltage-controlled current source. The control end of the voltage-controlled current source is connected to the first end of the logic control module, the first end of the voltage-controlled current source is connected to the first end of the anti-backflow module, and the second end of the voltage-controlled current source is connected to the second end of the protection controller;

[0014] The control end of the drive module is connected to the second end of the logic control module, or the control end of the drive module is connected to the first end of the logic control module, wherein the voltage-controlled current source and the drive module are not conducting simultaneously.

[0015] Optionally, the voltage-controlled current source includes a first transistor, a second transistor, a first resistor, and a second resistor. The first pole of the first transistor is connected to the first end of the anti-backflow module, the second pole of the first transistor is connected to the first pole of the second transistor, the second pole of the second transistor is connected to the second end of the protection controller, the first end of the first resistor is connected to the first end of the anti-backflow module, the second end of the first resistor and the first end of the second resistor are both connected to the control pole of the first transistor, the second end of the second resistor is connected to the second pole of the first transistor, and the control pole of the second transistor is connected to the first end or the second end of the logic control module;

[0016] The substrates of the first transistor and the second transistor are both connected to the second end of the protection controller.

[0017] Optionally, the number of the voltage-controlled current sources is multiple, and multiple voltage-controlled current sources are connected in parallel, and the controlled voltages of different voltage-controlled current sources are different.

[0018] Optionally, the driving module includes a third transistor and a third resistor. A first pole of the third transistor is connected to a first end of the protection controller. A second pole of the third transistor is connected to a first end of the third resistor. A second end of the third resistor is connected to a third end of the protection controller. A control pole of the third transistor is connected to a first end of the logic control module. A substrate of the third transistor is connected to the first end of the protection controller;

[0019] The matching module includes a fourth resistor, and the current limiting module includes a fifth resistor. A first end of the fourth resistor is connected to the second end of the third resistor. A second end of the fourth resistor is connected to a first end of the fifth resistor. A second end of the fifth resistor is connected to a second end of the battery protection circuit;

[0020] A resistance value of the fourth resistor is greater than a resistance value of the third resistor, and the resistance value of the fourth resistor is greater than a resistance value of the fifth resistor.

[0021] Optionally, the switching module includes a fourth transistor and a fifth transistor. A control pole of the fourth transistor is connected to a second end of the driving module. A control pole of the fifth transistor is connected to a third end of the driving module. A first pole of the fifth transistor is connected to a second end of the battery module. A second pole of the fifth transistor is connected to a second pole of the fourth transistor. A first pole of the fourth transistor is connected to a second end of the battery protection circuit. A substrate of the fifth transistor is connected to the second end of the battery module. A substrate of the fourth transistor is connected to the second end of the battery protection circuit.

[0022] According to another aspect of the present invention, a battery protection system is provided. The battery protection system includes the battery protection circuit provided in any embodiment of the present invention, and the battery module includes at least one battery.

[0023] In the technical solution provided by the embodiment of the present invention, both the driving module and the anti-backflow module are connected to the third end of the protection controller. By providing the anti-backflow module between the second end and the third end of the protection controller, after the switching module is turned off, the leakage current between the second end and the fourth end of the protection controller can be eliminated, and the influence of the leakage current caused by the non-isolated device in the protection controller being disposed on the PSUB on the reliability of the protection circuit can be avoided. At the same time, by providing the matching module between the fourth end and the third end of the protection controller, after the switching module is turned off, the potential between the fourth end and the third end of the protection controller can be matched to ensure that the switching module is turned off, which is beneficial to improving the reliability of the protection controller, thereby improving the reliability of the battery protection circuit.

[0024] It should be understood that the content described in this part is not intended to identify the key or important features of the embodiments of the present invention, nor is it used to limit the scope of the present invention. Other features of the present invention will become readily understood from the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0026] Figure 1 FIG. is a schematic structural diagram of a battery protection circuit provided by an embodiment of the present invention;

[0027] Figure 2 FIG. is a schematic structural diagram of another battery protection circuit provided by an embodiment of the present invention;

[0028] Figure 3 FIG. is a schematic structural diagram of another battery protection circuit provided by an embodiment of the present invention;

[0029] Figure 4 FIG. is a schematic structural diagram of a voltage-controlled current source provided by an embodiment of the present invention;

[0030] Figure 5 FIG. is a schematic structural diagram of another battery protection circuit provided by an embodiment of the present invention;

[0031] Figure 6 FIG. is a schematic structural diagram of another voltage-controlled current source provided by an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] In order to enable those skilled in the art to better understand the solutions of the present invention, the following clearly and completely describes the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, rather than all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0033] It should be noted that the terms "first", "second", etc. in the description, claims and above-mentioned drawings of the present invention are used to distinguish similar objects, and do not necessarily have to be used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the present invention described here can be implemented in an order other than those illustrated or described here. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0034] The battery protection circuit generally includes a protection controller. The protection controller usually adopts an isolated high-voltage process to isolate all circuit structures in the protection controller on the isolation ring. However, the size of the isolation device is large, occupying more area, resulting in a larger area and higher cost of the protection controller.

[0035] To solve the above problems, in the design solution, at least some transistors in the protection controller adopt non-isolated devices, and these non-isolated devices are arranged on the PSUB (i.e., P-type substrate). Taking the lowest battery voltage as the ground of the wafer, the substrate of the transistor is connected to the lowest battery voltage to ensure that all devices based on the PSUB are in the reverse bias state, avoiding the phenomenon of leakage caused by the conduction of parasitic PN junctions. Since non-isolated devices are used, the area of the protection controller can be effectively reduced and the cost can be lowered. However, because they are non-isolated devices, after the charging overcurrent protection or charging overvoltage protection action, when a negative voltage appears at the end of the protection controller connected to the negative electrode of the charger (determined by the charging characteristics), this will cause the protection controller to charge the battery through the parasitic diode, reducing the reliability of the protection circuit and affecting the charging state of the battery.

[0036] Therefore, the embodiments of the present invention provide a novel battery protection circuit to solve the leakage problem caused by the scheme of arranging devices on the PSUB.

[0037] Figure 1 The structural schematic diagram of a battery protection circuit provided by the embodiments of the present invention is shown in reference to Figure 1, the battery protection circuit provided by the embodiment of the present invention includes: a battery module 10, a switch module 30, a current limiting module 40, and a protection controller 20. The first end of the battery module 10 is connected to the first end P+ of the battery protection circuit and the first end A1 of the protection controller 20. The second end of the battery module 10 is connected to the first end of the switch module 30 and the second end A2 of the protection controller 20. The second end of the switch module 30 is connected to the second end P- of the battery protection circuit. The third end A3 of the protection controller 20 is connected to the control end of the switch module 30. The fourth end A4 of the protection controller 20 is connected to the first end of the current limiting module 40. The second end of the current limiting module 40 is connected to the second end P- of the battery protection circuit.

[0038] The protection controller 20 includes a logic control module 101, a driving module 102, an anti-backflow module 103, and a matching module 104. The first end of the driving module 102 is connected to the first end A1 of the protection controller 20. The second end of the driving module 102 is connected to the third end A3 of the protection controller 20. The control end of the driving module 102 is connected to the logic control module 101. The driving module 102 is used to control whether the switch module 30 is turned on or off in response to the signal output by the logic control module 101. The anti-backflow module 103 is connected between the second end A2 of the protection controller 20 and the second end of the driving module 102, that is, between the second end A2 and the third end A3 of the protection controller 20. The anti-backflow module 103 is used to prevent the current at the fourth end A4 of the protection controller 20 from flowing into the second end of the battery module 10 after the switch module 30 is turned off. The matching module 104 is connected between the third end A3 (the second end of the driving module 102) of the protection controller 20 and the fourth end A4 of the protection controller 20. The matching module 104 is used to match the potentials between the third end A3 and the fourth end A4 of the protection controller 20.

[0039] Specifically, the battery module 10 may include one battery or multiple batteries connected in series. The first end of the battery module 10 is the positive electrode of the highest battery, and the second end of the battery module 10 is the negative electrode of the lowest battery. A charger or a load may be connected between the first end and the second end of the battery protection circuit. The current limiting module 40 is used to limit the current when the charger is reversely connected.

[0040] The protection controller 20 is used to protect the charging and discharging of the battery module 10. Among them, the logic control module 101 can judge the current state of the battery module 10 according to the battery voltage, and thus output different control signals. The driving module 102 responds to the control signal output by the logic control module 101 to control the switch module 30 to turn on or off, so as to turn on or cut off the charging and discharging path of the battery module 10.

[0041] It should be noted that the protection controller 20 further includes other protection modules, and the fourth terminal of the protection controller 20 is also connected to other protection modules. After the driving module 102 controls the switch module 30 to turn off, if a negative voltage appears at the second terminal of the battery protection circuit P- (that is, the fourth terminal A4 of the protection controller 20 is at a negative voltage), a current will conduct between the second terminal A2 and the fourth terminal A4 of the protection controller 20 through the parasitic diode, and the current cannot be completely blocked. For example, taking the charger voltage of 20V and the battery module 10 voltage of 8V as an example, during the charging process, the switch module 30 is turned on, and the voltage VSS at the second terminal of the battery module 10 is approximately equal to the voltage at the second terminal P- of the battery protection circuit. When the battery module 10 is fully charged, the switch module 30 is turned off, and the voltage at the second terminal P- of the battery protection circuit is -12V, which is less than the voltage VSS at the second terminal of the battery module 10 (taking VSS as the zero potential), resulting in current flowing from the second terminal of the battery module 10 to the second terminal P- of the battery protection circuit (due to process reasons, there is a parasitic diode pointing from VSS to P-), and the charging current cannot be completely blocked.

[0042] In this embodiment, an anti-backflow module 103 is provided between the second terminal of the battery module 10 and the second terminal of the driving module 102. After the switch module 30 is turned off, the anti-backflow module 103 can cut off the current path between the second terminal of the battery module 10 and the second terminal P- of the battery protection circuit, thereby eliminating the leakage phenomenon. In addition, when the switch module 30 is turned off, the voltage at the third terminal A3 of the protection controller 20 is isolated from the voltage at the second terminal of the battery module 10. By setting a matching module 104, the potentials of the third terminal A3 and the fourth terminal A4 of the protection controller 20 are matched to ensure that the voltage at the third terminal A3 of the protection controller 20 can turn off the switch module 30.

[0043] For the technical solution provided by the embodiment of the present invention, both the driving module 102 and the anti-backflow module 103 are connected to the third terminal A3 of the protection controller 20. By setting the anti-backflow module 103 between the second terminal A2 and the third terminal A3 of the protection controller 20, the leakage current between the second terminal A2 and the fourth terminal A4 of the protection controller 20 can be eliminated after the switch module 30 is turned off, avoiding the influence of the leakage current caused by the non-isolated devices in the protection controller 20 being disposed on the PSUB on the reliability of the protection circuit. At the same time, by setting the matching module 104 between the fourth terminal A4 and the third terminal A3 of the protection controller 20, the potentials between the fourth terminal A4 and the third terminal A3 of the protection controller 20 can be matched after the switch module 30 is turned off to ensure that the switch module 30 is turned off, which is beneficial to improving the reliability of the protection controller and thus improving the reliability of the battery protection circuit.

[0044] Figure 2 For another structural schematic diagram of the battery protection circuit provided by the embodiment of the present invention, refer to Figure 2, based on the above embodiments, optionally, the anti-backflow module 103 includes a diode DIO. The negative electrode of the diode DIO is connected to the second terminal A2 of the protection controller 20, and the positive electrode of the diode DIO is connected to the second terminal of the driving module 102, that is, the positive electrode of the diode DIO is connected to the third terminal A3 of the protection controller 20. According to the one-way conductivity of the diode DIO, when the voltage at the second terminal P- of the battery protection circuit is less than the voltage VSS at the second terminal of the battery module 10, the diode DIO is cut off, thereby effectively cutting off the leakage current path between the second terminal of the battery module 10 and the second terminal P- of the battery protection circuit.

[0045] The structure of the anti-backflow module 103 provided in this embodiment is simple, which is beneficial to reducing the area of the protection controller 20 and lowering the cost.

[0046] Of course, in other embodiments, the anti-backflow module 103 can also be composed of transistors as long as the anti-backflow function can be achieved.

[0047] Figure 3 is a schematic structural diagram of another battery protection circuit provided by an embodiment of the present invention. Refer to Figure 3 , based on the above embodiments, optionally, the driving module 102 includes a third transistor Q3 and a third resistor R3. The first pole of the third transistor Q3 is connected to the first terminal A1 of the protection controller 20, the second pole of the third transistor Q3 is connected to the first terminal of the third resistor R3, the second terminal of the third resistor R3 is connected to the third terminal A3 of the protection controller 20, the control pole of the third transistor Q3 is connected to the first terminal of the logic control module 101, and the substrate of the third transistor Q3 is connected to the first terminal A1 of the protection controller 20; the matching module 104 includes a fourth resistor R4, and the current limiting module 40 includes a fifth resistor R5. The first terminal of the fourth resistor R4 is connected to the second terminal of the third resistor R3, the second terminal of the fourth resistor R4 is connected to the first terminal of the fifth resistor R5, and the second terminal of the fifth resistor R5 is connected to the second terminal P- of the battery protection circuit.

[0048] The switching module 30 includes a fourth transistor Q4 and a fifth transistor Q5. The control pole of the fourth transistor Q4 is connected to the second terminal of the driving module 102, the control pole of the fifth transistor Q5 is connected to the third terminal of the driving module 102 (another driving branch can also be included inside the driving module 102 and connected to its own third terminal to output a control signal to the control pole of the fifth transistor Q5), the first pole of the fifth transistor Q5 is connected to the second terminal of the battery module 10, the second pole of the fifth transistor Q5 is connected to the second pole of the fourth transistor Q4, the first pole of the fourth transistor Q4 is connected to the second terminal P- of the battery protection circuit, the substrate of the fifth transistor Q5 is connected to the second terminal of the battery module 10, and the substrate of the fourth transistor Q4 is connected to the second terminal P- of the battery protection circuit.

[0049] In this embodiment, the resistance value of the fourth resistor R4 is greater than that of the third resistor R3, and the resistance value of the fourth resistor R4 is greater than that of the fifth resistor R5. For example, the resistance value of the third resistor R3 is several tens of KΩ, the resistance value of the fourth resistor R4 is between several MΩ and several tens of MΩ, and the resistance value of the fifth resistor R5 is several KΩ.

[0050] When the battery protection circuit does not enter the charging anomaly (including overcurrent charging anomaly and overvoltage charging anomaly) protection state, the second terminal of the driving module 102 outputs a high-level control signal, the fourth transistor Q4 is turned on, and the voltage of the control electrode of the fourth transistor Q4 is ; where r3 is the resistance value of the third resistor R3, r4 is the resistance value of the fourth resistor R4, r5 is the resistance value of the fifth resistor R5, and VP- is the voltage of the second terminal P- of the battery protection circuit. Since the resistance value of the fourth resistor R4 is much greater than that of the third resistor R3, the voltage of the control electrode of the fourth transistor Q4 is approximately VDD.

[0051] When the battery protection circuit enters the charging anomaly protection state, the second terminal of the driving module 102 outputs a low-level control signal, the fourth transistor Q4 is turned off, and the control electrode of the fourth transistor Q4 is connected to the second terminal P- of the battery protection circuit through the fourth resistor R4 and the fifth resistor R5.

[0052] During the process in which the voltage of the control electrode of the fourth transistor Q4 jumps from a high level to a low level, since the internal resistance of the fourth transistor Q4 is small, the parasitic capacitance of its control electrode is large, and the resistance value of the fourth resistor R4 is large, the conduction ability of the fourth resistor R4 is insufficient, resulting in a long time required for the voltage of the control electrode of the fourth transistor Q4 to drop from VDD to VP-, increasing the turn-off delay during charging anomalies, and making the fourth transistor Q4 more vulnerable to interference when turned off, resulting in the fourth transistor Q4 switching repeatedly, and even burning out the fourth transistor Q4 in severe cases.

[0053] Continue to refer to Figure 3 In this embodiment, the protection controller 20 further includes a discharge module 105. The first terminal of the discharge module 105 is connected to the first terminal of the anti-backflow module 103, the second terminal of the anti-backflow module 103 is connected to the second terminal of the driving module 102, and the second terminal of the discharge module 105 is connected to the second terminal A2 of the protection controller 20. The discharge module 105 is configured to discharge the control terminal of the switching module 30 when the voltage of the control terminal of the switching module 30 is greater than a preset voltage during the turn-off process of the switching module 30, and to remain turned off when the voltage of the control terminal of the switching module 30 is less than or equal to the preset voltage.

[0054] Among them, the conduction ability of the discharge module 105 is greater than that of the matching module 104. When the discharge module 105 conducts, the voltage at the control electrode of the fourth transistor Q4 can be rapidly reduced through the anti-backflow module 103 and the discharge module 105. And when the voltage at the control electrode of the fourth transistor Q4 is less than or equal to the preset voltage, the discharge module 105 turns off and no longer provides a discharge path for the control electrode of the fourth transistor Q4. The control electrode of the fourth transistor Q4 discharges through the fourth resistor R4 and the fifth resistor R5. Compared with the technical solution that only discharges through the fourth resistor R4 and the fifth resistor R5, the technical solution provided in this embodiment can rapidly pull down the voltage at the control electrode of the fourth transistor Q4, which is beneficial to improving the anti-interference ability of the fourth transistor Q4.

[0055] Optionally, in this embodiment, the discharge module 105 includes a voltage-controlled current source. The control terminal of the voltage-controlled current source is connected to the first terminal of the logic control module 101. The first terminal of the voltage-controlled current source is connected to the first terminal of the anti-backflow module 103. The second terminal of the voltage-controlled current source is connected to the second terminal A2 of the protection controller 20. The control terminal of the drive module 102 is connected to the second terminal of the logic control module 101 and shares the same control signal with the control terminal of the voltage-controlled current source, or the control terminal of the drive module 102 is connected to the first terminal of the logic control module 101 and uses a different control signal from the control terminal of the voltage-controlled current source. Among them, the voltage-controlled current source and the drive module 102 do not conduct simultaneously.

[0056] Figure 4 is a schematic structural diagram of a voltage-controlled current source provided by an embodiment of the present invention. Refer to Figure 3 and Figure 4 , the voltage-controlled current source 115 includes a first transistor Q1, a second transistor Q2, a first resistor R1, and a second resistor R2. The first pole of the first transistor Q1 is connected to the first terminal of the anti-backflow module 103. The second pole of the first transistor Q1 is connected to the first pole of the second transistor Q2. The second pole of the second transistor Q2 is connected to the second terminal A2 of the protection controller 20. The first terminal of the first resistor R1 is connected to the first terminal of the anti-backflow module 103. The second terminal of the first resistor R1 and the first terminal of the second resistor R2 are both connected to the control electrode of the first transistor Q1. The second terminal of the second resistor R2 is connected to the second pole of the first transistor Q1. The control electrode of the second transistor Q2 is connected to the first terminal or the second terminal of the logic control module 101. The substrates of the first transistor Q1 and the second transistor Q2 are both connected to the second terminal A2 of the protection controller 20.

[0057] Specifically, when the battery protection circuit does not enter the charging abnormal protection state, the logic control module 101 controls the third transistor Q3 to conduct and controls the second transistor Q2 to turn off (here, the third transistor Q3 and the second transistor Q2 can be transistors of different channel types). The discharge module 105 is in the off state, the second terminal of the driving module 102 outputs a high-level control signal, the fourth transistor Q4 conducts, and the voltage of the control pole of the fourth transistor Q4 is , since the resistance value of the fourth resistor R4 is much larger than that of the third resistor R3, therefore, the voltage of the control pole of the fourth transistor Q4 is approximately VDD.

[0058] When the battery protection circuit enters the charging abnormal protection state, the logic control module 101 controls the third transistor Q3 to turn off and controls the second transistor Q2 to conduct. The conduction ability of the first transistor Q1 is greater than that of the fourth resistor R4. The control pole of the fourth transistor Q4 is quickly discharged through the anti-backflow module 103, the first transistor Q1, and the second transistor Q2. As the voltage of the control pole of the fourth transistor Q4 gradually decreases, the voltage of the control pole of the first transistor Q1 after being divided by the first resistor R1 and the second resistor R2 becomes smaller, the conduction ability of the first transistor Q1 decreases, and the discharge current gradually decreases. When the voltage of the control pole of the fourth transistor Q4 drops to a preset voltage (the preset voltage is the voltage that causes the first transistor Q1 to turn off after being divided by the first resistor R1 and the second resistor R2), the first transistor Q1 turns off, and the current of the voltage-controlled current source 115 drops to zero. The control pole of the fourth transistor Q4 is discharged only through the fourth resistor R4 and the fifth resistor R5.

[0059] The technical solution provided by the embodiment of the present invention, when the fourth transistor Q4 switches from the conduction state to the off state, quickly discharges the voltage of the control pole of the fourth transistor Q4 through the voltage-controlled current source 115 to ensure that the fourth transistor Q4 can be quickly turned off, which is beneficial to improving the turn-off reliability of the fourth transistor Q4. In addition, since the current of the voltage-controlled current source 115 is voltage-controlled, therefore, as the voltage of the control pole of the fourth transistor Q4 changes, the current generated by the first transistor Q1 also changes accordingly, so as to smooth the change speed of the voltage of the control pole of the fourth transistor Q4 and prevent the fourth transistor Q4 from being burned out due to too fast voltage change speed.

[0060] Figure 5 is a schematic structural diagram of another battery protection circuit provided by the embodiment of the present invention, Figure 6 is a schematic structural diagram of another voltage-controlled current source provided by the embodiment of the present invention. Refer to Figure 5 and Figure 6, based on the above embodiments, optionally, the number of voltage-controlled current sources 115 can be multiple, and multiple voltage-controlled current sources 115 are connected in parallel, and the controlled voltages of different voltage-controlled current sources 115 are different. Here, by adjusting the resistance values of the first resistor R1 and the second resistor R2, the voltage of the control electrode of the first transistor Q1 can be adjusted, that is, the controlled voltage of the voltage-controlled current source 115 can be adjusted, so as to control the voltage of the control electrode of the fourth transistor Q4 at different falling stages through multiple voltage-controlled current sources, which is beneficial to further smooth the change speed of the voltage of the control electrode of the fourth transistor Q4. Exemplarily, taking the discharge module 105 including two voltage-controlled current sources 115 as an example, the first voltage-controlled current source 1151 and the second voltage-controlled current source 1152 are connected in parallel, and the resistance values of the first resistor R1 and the second resistor R2 in the first voltage-controlled current source 1151 are different from the resistance values of the first resistor R1 and the second resistor R2 in the second voltage-controlled current source 1152. Assuming VDD = 8V, when the voltage of the control electrode of the fourth transistor Q4 is in the range of 8V to 4V, the control electrode of the fourth transistor Q4 discharges through the anti-backflow module 103 and the first voltage-controlled current source 1151; when the voltage of the control electrode of the fourth transistor Q4 is in the range of 4V to 0V, the control electrode of the fourth transistor Q4 discharges through the anti-backflow module 103 and the second voltage-controlled current source 1152. By reasonably configuring the resistance values of the first resistor R1 and the second resistor R2 in the first voltage-controlled current source 1151 and the second voltage-controlled current source 1152, the falling speed of the voltage of the control electrode of the fourth transistor Q4 at different voltage stages can be adjusted to meet different design requirements.

[0061] It should be noted that since the first pole of the fifth transistor Q5 is itself connected to the second end of the battery module 10, there will be no leakage current problem when the fifth transistor Q5 is turned off. In addition, the third transistor Q3 is a P-type transistor, and its substrate can be connected to the voltage VDD at the first end of the battery module 10.

[0062] The technical solution provided by the embodiments of the present invention can prevent the charging current from flowing back by setting the discharge module 105 and the anti-backflow module 103, so as to eliminate the leakage current of the protection controller 20 and improve the turn-off speed of the fourth transistor Q4, thereby improving the reliability of the battery protection circuit, so that the protection controller 20 can implement the non-isolated device solution. Among them, compared with the isolated device, the non-isolated device has a smaller area, so that the area of the protection controller 20 can be greatly reduced, and the cost can be effectively reduced.

[0063] Optionally, an embodiment of the present invention further provides a battery protection system, which includes the battery protection circuit provided in any of the above embodiments. Therefore, the battery protection system provided in this embodiment also has the beneficial effects described in any of the above embodiments. Among them, the battery module 10 in the battery protection circuit includes at least one battery, that is, the battery module 10 can be a single battery or a battery pack formed by connecting multiple batteries in series.

[0064] It should be understood that various forms of the processes shown above can be used, steps can be reordered, added or deleted. For example, the steps described in the present invention can be executed in parallel, sequentially, or in a different order, as long as the desired results of the technical solution of the present invention can be achieved, and no limitation is made herein.

[0065] The above specific embodiments do not constitute a limitation to the protection scope of the present invention. Those skilled in the art should understand that various modifications, combinations, sub - combinations and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention should be included within the protection scope of the present invention.

Claims

1. A battery protection circuit, characterized in that, Comprising: A battery module, a switch module, a current limiting module, and a protection controller. The first end of the battery module is connected to the first end of the battery protection circuit and the first end of the protection controller. The second end of the battery module is connected to the first end of the switch module and the second end of the protection controller. The second end of the switch module is connected to the second end of the battery protection circuit. The third end of the protection controller is connected to the control end of the switch module. The fourth end of the protection controller is connected to the first end of the current limiting module. The second end of the current limiting module is connected to the second end of the battery protection circuit; The protection controller includes a logic control module, a drive module, an anti-backflow module, and a matching module; The first end of the drive module is connected to the first end of the protection controller. The second end of the drive module is connected to the third end of the protection controller. The control end of the drive module is connected to the logic control module. The drive module is used to control whether the switch module is turned on or off in response to a signal output by the logic control module; The anti-backflow module is connected between the second end of the protection controller and the second end of the drive module. The anti-backflow module is used to prevent the current at the fourth end of the protection controller from flowing into the second end of the battery module after the switch module is turned off. The matching module is connected between the third end and the fourth end of the protection controller. The matching module is used to match the potential between the third end and the fourth end of the protection controller; The protection controller further includes a discharge module. The first end of the discharge module is connected to the first end of the anti-backflow module. The second end of the anti-backflow module is connected to the second end of the drive module. The second end of the discharge module is connected to the second end of the protection controller. The discharge module is used to discharge the control end of the switch module when the voltage at the control end of the switch module is greater than a preset voltage during the process of turning off the switch module.

2. The battery protection circuit according to claim 1, wherein The anti-backflow module includes a diode. The negative pole of the diode is connected to the second end of the protection controller. The positive pole of the diode is connected to the second end of the drive module.

3. The battery protection circuit according to claim 1, wherein The discharge module is further used to remain off when the voltage at the control end of the switch module is less than or equal to the preset voltage.

4. The battery protection circuit according to claim 3, wherein The conduction ability of the discharge module is greater than that of the matching module.

5. The battery protection circuit according to claim 3, wherein The discharge module includes a voltage-controlled current source. The control end of the voltage-controlled current source is connected to the first end of the logic control module. The first end of the voltage-controlled current source is connected to the first end of the anti-backflow module. The second end of the voltage-controlled current source is connected to the second end of the protection controller; The control end of the drive module is connected to the second end of the logic control module, or the control end of the drive module is connected to the first end of the logic control module, wherein the voltage-controlled current source and the drive module are not turned on simultaneously.

6. The battery protection circuit according to claim 5, wherein, The voltage-controlled current source includes a first transistor, a second transistor, a first resistor, and a second resistor. A first pole of the first transistor is connected to a first end of the anti-backflow module. A second pole of the first transistor is connected to a first pole of the second transistor. A second pole of the second transistor is connected to a second end of the protection controller. A first end of the first resistor is connected to the first end of the anti-backflow module. A second end of the first resistor and a first end of the second resistor are both connected to a control pole of the first transistor. A second end of the second resistor is connected to the second pole of the first transistor. A control pole of the second transistor is connected to a first end or a second end of the logic control module; A substrate of the first transistor and a substrate of the second transistor are both connected to the second end of the protection controller.

7. The battery protection circuit according to claim 5, wherein, The number of the voltage-controlled current sources is multiple, and the multiple voltage-controlled current sources are connected in parallel, and controlled voltages of different voltage-controlled current sources are different.

8. The battery protection circuit according to claim 1, wherein The driving module includes a third transistor and a third resistor. A first pole of the third transistor is connected to a first end of the protection controller. A second pole of the third transistor is connected to a first end of the third resistor. A second end of the third resistor is connected to a third end of the protection controller. A control pole of the third transistor is connected to the first end of the logic control module. A substrate of the third transistor is connected to the first end of the protection controller; The matching module includes a fourth resistor, and the current-limiting module includes a fifth resistor. A first end of the fourth resistor is connected to the second end of the third resistor. A second end of the fourth resistor is connected to a first end of the fifth resistor. A second end of the fifth resistor is connected to a second end of the battery protection circuit; A resistance value of the fourth resistor is greater than a resistance value of the third resistor, and the resistance value of the fourth resistor is greater than a resistance value of the fifth resistor.

9. The battery protection circuit according to claim 1, wherein, The switching module includes a fourth transistor and a fifth transistor. A control pole of the fourth transistor is connected to a second end of the driving module. A control pole of the fifth transistor is connected to a third end of the driving module. A first pole of the fifth transistor is connected to a second end of the battery module. A second pole of the fifth transistor is connected to a second pole of the fourth transistor. A first pole of the fourth transistor is connected to the second end of the battery protection circuit. A substrate of the fifth transistor is connected to the second end of the battery module. A substrate of the fourth transistor is connected to the second end of the battery protection circuit.

10. A battery protection system, characterized in that, The battery protection circuit according to any one of claims 1-9 is included, and the battery module includes at least one battery.

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