A battery protection circuit

Abstract

This application relates to the field of battery technology and discloses a battery protection circuit, including a first protection control module, whose input terminal is connected to the positive terminal of the battery cell and whose output terminal is connected to the negative terminal of the battery cell; a second protection control module connected in parallel with the first protection control module; and a metering module, including a fuel gauge chip U3 and a linkage unit. The enable pin CE of the fuel gauge chip U3 is connected to the linkage unit, and the linkage unit is connected to both the first and second protection control modules. This application uses a linkage unit to control the operating state of the fuel gauge chip U3 based on the high or low voltage levels of the first or second protection control module, achieving fuel gauge shutdown during over-discharge protection, significantly reducing the overall power consumption of the protection board, avoiding the continuous depletion of the remaining battery power, effectively protecting the battery, thereby improving battery life and enhancing safety.

Description

Technical Field

[0001] This application belongs to the field of battery technology, specifically relating to a battery protection circuit. Background Technology

[0002] In applications such as portable electronic devices and energy storage systems, batteries are the core power supply components, and their safety and battery life are of paramount importance. Battery protection circuits with fuel gauges typically use a combination of protection ICs and MOSFETs to monitor abnormalities such as overvoltage charging, undervoltage discharging, and overcurrent. When triggered, the MOSFET is disconnected to cut off the circuit and protect the battery.

[0003] However, in existing solutions, regardless of whether overvoltage, undervoltage, or overcurrent protection is triggered, the fuel gauge IC always maintains normal operating mode. This makes it difficult to reduce the overall power consumption of the protection board. If the battery is stored for a long time and cannot be recharged regularly, the fuel gauge will continuously consume power, constantly depleting the remaining battery capacity. When the capacity drops to a critical value, it can easily cause irreversible damage to the battery, significantly shortening its lifespan and even posing safety hazards. Utility Model Content

[0004] To address the shortcomings of the prior art, this application provides a battery protection circuit. By employing a linkage unit to control the working state of the fuel gauge chip U3 based on the high or low level of the first or second protection control module, the fuel gauge is shut down during over-discharge protection, significantly reducing the overall power consumption of the protection board, avoiding the phenomenon of continuously consuming the remaining battery power, effectively protecting the battery, thereby improving battery life and enhancing safety.

[0005] The technical effects to be achieved in this application are realized through the following aspects: This application provides a battery protection circuit, including: The first protection control module has its input terminal connected to the positive terminal of the battery cell and its output terminal connected to the negative terminal of the battery cell. The second protection control module is connected in parallel with the first protection control module, and The metering module includes a fuel meter chip U3 and a linkage unit. The enable pin CE of the fuel meter chip U3 is connected to the linkage unit, and the linkage unit is connected to the first protection control module and the second protection control module respectively. The linkage unit is used to control the working state of the power meter chip U3 according to the high or low level of the first protection control module or the second protection control module.

[0006] In some implementations, the linkage unit includes: Diode D4 has its cathode connected to the discharge output terminal of the first protection control module, and its anode connected to the enable pin CE of the fuel meter chip U3 through resistor R7. Diode D3, its cathode is connected to the discharge output terminal of the second protection control module, and its anode is connected to the anode of diode D4; and Resistor R18, one end of which is connected to the anode of diode D4 and the anode of diode D3, and the other end of resistor R18 is connected to the positive terminal of the battery cell.

[0007] In some implementations, the first protection module includes a protection chip U1 and a first power switch unit. The positive power supply pin VDD of the protection chip U1 is connected to the positive terminal of the battery cell, and the discharge control output pin DO of the protection chip U1 is connected to the linkage unit. The input terminal of the first power switch unit is connected to the discharge control output pin DO of the protection chip U1, and the output terminal of the first power switch is connected to the negative terminal of the battery cell.

[0008] In some implementations, the first power switching power supply includes transistors Q3 and Q4 connected in parallel. The main signal input terminal G1 of transistor Q3 is connected to the discharge control output pin DO of the protection chip U1, and the main signal input terminal G1 of transistor Q4 is connected to the discharge control output pin DO of the protection chip U1.

[0009] In some implementations, the second protection module includes a protection chip U2 and a second power switch unit. The positive power supply pin VDD of the protection chip U2 is connected to the positive terminal of the battery cell, and the discharge control output pin DO of the protection chip U2 is connected to the linkage unit. The input terminal of the second power switch unit is connected to the discharge control output pin DO of the protection chip U2, and the output terminal of the second power switch is connected to the negative terminal of the battery cell.

[0010] In some implementations, the second power switching power supply includes transistors Q1 and Q2 connected in parallel. The main signal input terminal G1 of transistor Q1 is connected to the discharge control output pin DO of the protection chip U2, and the main signal input terminal G1 of transistor Q2 is connected to the discharge control output pin DO of the protection chip U2.

[0011] In some implementations, the resistance of resistor R18 is 2 megohms.

[0012] In some implementations, the fuel gauge chip U3 is either BQ27Z561 or SH366100G / 012GY.

[0013] In some implementations, the protection chip U1 is model number Zhongying SH366302R5 / 006R5Y / BAT00.

[0014] In some implementations, the protection chip U2 is model number Zhongying SH366302R5 / 006R5Y / BAT00.

[0015] In summary, this application has at least the following advantages: 1. The battery protection circuit provided in this application, through the design of the fuel gauge chip U3 and the linkage unit, allows the fuel gauge chip U3 to enter a shutdown or low-power mode when the output level of the first protection control module or the second protection control module is low; conversely, when the output level of the first protection control module or the second protection control module is high, the fuel gauge chip U3 operates normally. This achieves the fuel gauge shutdown during over-discharge protection, significantly reduces the overall power consumption of the protection board, avoids the phenomenon of continuously consuming the remaining battery power, effectively protects the battery, and thus improves the battery's lifespan and enhances its safety.

[0016] 2. The battery protection circuit provided in this application does not require additional control chips or complex circuits. It has a simple structure, low cost, strong practicality, and high reliability, making it suitable for low-cost lithium battery applications that are sensitive to power consumption. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the battery protection circuit in Embodiment 1 of this application.

[0018] Figure 2 This is a schematic diagram of the metering module in Embodiment 1 of this application.

[0019] Figure 3 This is a schematic diagram of the battery protection circuit in Embodiment 2 of this application.

[0020] Marked in the image: 1. First protection control module; 11. First power switch unit; 2. Second protection control module; 21. Second power switch unit; 3. Metering module; 31. Linkage unit. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. The described embodiments are only some embodiments of this application, not all embodiments.

[0022] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application.

[0023] Example 1: Please see the appendix Figure 1 The battery protection circuit of this application includes a first protection control module 1, a second protection control module 2, and a metering module 3.

[0024] The first protection control module 1 has its input terminal connected to the positive terminal of the battery cell and its output terminal connected to the negative terminal of the battery cell; the second protection control module 2 is connected in parallel with the first protection control module 1; the metering module 3 includes a fuel gauge chip U3 and a linkage unit 31, the enable pin CE of the fuel gauge chip U3 is connected to the linkage unit 31, and the linkage unit 31 is connected to the first protection control module 1 and the second protection control module 2 respectively; the linkage unit 31 is used to control the working state of the fuel gauge chip U3 according to the high or low level of the first protection control module 1 or the second protection control module 2.

[0025] The first protection control module 1 and the second protection control module 2 serve as a "dual insurance," i.e., two levels of protection. The first level of protection monitors the battery voltage and current in real time. Upon detecting abnormalities such as overcharging leading to excessive voltage, over-discharging leading to excessive voltage, or overcurrent leading to excessive current, it quickly outputs a signal to control the MOSFET to turn off, cutting off the charging / discharging circuit. This is the basic line of defense. When the first level of protection fails, such as due to a faulty first-level protection chip or a short circuit in the MOSFET causing overvoltage, it will trigger forced protection upon detecting the abnormality, completely disconnecting the battery from the external environment to avoid danger.

[0026] The U3 battery meter chip is used to accurately collect data such as battery voltage, current, and temperature. Through algorithms, it calculates the remaining power, charging / discharging status, and battery health, providing the device with power display and battery life prediction, allowing users to understand the battery status.

[0027] In this embodiment, when the battery protection circuit is working normally, the output level of the first protection control module 1 and the second protection control module 2 is high, the level of the enable pin CE of the fuel gauge chip U3 is high, and the fuel gauge chip U3 is working normally.

[0028] When the over-discharge protection is triggered, the output levels of the first protection control module 1 and the second protection control module 2 are low. The linkage unit 31 pulls down the level of the enable pin CE of the fuel meter chip U3 to a low voltage, forcing the fuel meter chip U3 to enter the shutdown / low power mode.

[0029] When the recovery condition is met, the battery voltage recovers after charging, the level of the first protection control module 1 returns to a high level, and the voltage of the enable pin CE of the fuel gauge chip U3 rises through the linkage unit 31, causing the fuel gauge chip U3 to restart.

[0030] The technical solution of this application, through the design of the fuel gauge chip U3 and the linkage unit 31, allows the fuel gauge chip U3 to enter a shutdown or low-power mode when the output level of the first protection control module 1 or the second protection control module 2 is low; conversely, when the output level of the first protection control module 1 or the second protection control module 2 is high, the fuel gauge chip U3 operates normally. This achieves the fuel gauge shutdown during over-discharge protection, significantly reduces the overall power consumption of the protection board, avoids the phenomenon of continuously consuming the remaining battery power, effectively protects the battery, and thus improves the battery's lifespan and enhances its safety.

[0031] In addition, this structure does not require additional control chips or complex circuits. The overall circuit design is simple, low-cost, highly practical, and highly reliable, making it suitable for low-cost lithium battery applications that are sensitive to power consumption.

[0032] In some embodiments, please refer to the appendix Figure 2 The linkage unit 31 includes diodes D4 and D3 and resistor R18. Diode D4's cathode is connected to the discharge output terminal of the first protection control module 1, and its anode is connected to the enable pin CE of the fuel gauge chip U3 via resistor R7. Diode D3's cathode is connected to the discharge output terminal of the second protection control module 2, and its anode is connected to the anode of diode D4. One end of resistor R18 is connected to the anodes of both diodes D4 and D3, and the other end is connected to the positive terminal of the battery cell. Preferably, diodes D4 and D3 are selected from Crystalmicro 1N4148WT diodes.

[0033] Specifically, diode D4 is connected to the discharge output terminal of the first protection control module 1, and diode D3 is connected to the discharge output terminal of the second protection control module 2. When either protection module triggers discharge protection, such as over-discharge or over-current, the discharge output terminal of the protection module will output a low-level signal. The corresponding diode D4 or diode D3 enters the forward conduction state due to "cathode low, anode high," and the signal is transmitted to the enable pin CE of the fuel gauge chip U3 through resistor R7, causing its level to change from high to low, thus putting the fuel gauge chip U3 into shutdown or low-power mode. During normal operation, the discharge output terminal of the protection module is high, diodes D3 and D4 are reverse-biased and cut off, and resistor R18 pulls the anode node up to the positive terminal voltage of the battery cell, keeping the enable pin CE of the fuel gauge chip U3 high, and the fuel gauge operates normally.

[0034] The above technical solution achieves automatic linkage between discharge protection and fuel gauge sleep mode, solving the problem of "continuous power consumption of the fuel gauge after protection" in traditional solutions. Especially in long-term battery storage scenarios, the fuel gauge power consumption is reduced from a typical value of 95uA to ≤0.85uA, significantly reducing the overall power consumption of the protection board, preventing irreversible capacity decay caused by continuous battery discharge, effectively extending battery life, and improving safety. Furthermore, the unidirectional conductivity of diodes D3 and D4 ensures that the signals of the two protection modules do not interfere with each other, improving circuit stability.

[0035] This structure eliminates the need for complex logic chips, simplifying design and reducing costs while ensuring functional reliability, making it suitable for the miniaturization and low-cost requirements of battery protection boards.

[0036] Example 2: The difference between this embodiment and Embodiment 1 is that, please refer to... Figure 3 The first protection module in this embodiment includes a protection chip U1 and a first power switch unit 11. The positive power supply pin VDD of the protection chip U1 is connected to the positive terminal of the battery cell, and the discharge control output pin DO of the protection chip U1 is connected to the linkage unit 31. The input terminal of the first power switch unit 11 is connected to the discharge control output pin DO of the protection chip U1, and the output terminal of the first power switch is connected to the negative terminal of the battery cell.

[0037] In this embodiment, the protection chip U1 of the first protection module is connected to the positive terminal of the battery cell through its VDD pin to obtain operating power and monitor the battery cell voltage in real time. When the battery cell experiences abnormalities such as over-discharge or over-current, the discharge control output pin DO of the protection chip U1 outputs a low-level signal. The discharge control output pin DO of the protection chip U1 is connected to the linkage unit 31, and the low-level signal is transmitted to the enable pin CE of the fuel gauge chip U3 through diode D4, triggering the fuel gauge to enter a low-power mode. At the same time, the discharge control output pin DO of the protection chip U1 drives the first power switch unit 11 to disconnect the discharge circuit and terminate the battery cell discharge.

[0038] The discharge control output pin DO of the protection chip U1 simultaneously controls the power switch and the fuel gauge, achieving synchronization between protection actions and power consumption control. In case of an abnormality, the discharge circuit can be quickly cut off to prevent further damage to the battery cell. When the linked fuel gauge enters low power consumption mode, it can avoid continuous power consumption after the battery is over-discharged, effectively extending the storage life.

[0039] In some embodiments, the first power switching power supply includes transistors Q3 and Q4 connected in parallel. The main signal input terminal G1 of transistor Q3 is connected to the discharge control output pin DO of the protection chip U1, and the main signal input terminal G1 of transistor Q4 is connected to the discharge control output pin DO of the protection chip U1.

[0040] Specifically, transistors Q3 and Q4 are connected in parallel to form a discharge path. The main signal input terminal G1 of transistors Q3 and Q4 is connected to the discharge control output pin DO of the protection chip U1. During normal discharge, the discharge control output pin DO of the protection chip U1 outputs a high level, transistors Q3 and Q4 are turned on, and current flows out from the negative terminal of the battery cell. When the discharge control output pin DO of the protection chip U1 outputs a low level, transistors Q3 and Q4 are simultaneously turned off, cutting off the discharge circuit.

[0041] Through the above technical solution, the parallel structure reduces the equivalent on-resistance. According to the formula P=I²R, this reduces power loss during discharge and improves energy efficiency. Furthermore, the parallel connection of the two MOSFETs in this structure can withstand a larger discharge current, and the other MOSFET can still partially operate even if one fails, enhancing reliability and effectively reducing the risk of circuit failure.

[0042] In some embodiments, the second protection module includes a protection chip U2 and a second power switch unit 21. The positive power supply pin VDD of the protection chip U2 is connected to the positive terminal of the battery cell, and the discharge control output pin DO of the protection chip U2 is connected to the linkage unit 31. The input terminal of the second power switch unit 21 is connected to the discharge control output pin DO of the protection chip U2, and the output terminal of the second power switch is connected to the negative terminal of the battery cell. The second power switching power supply includes transistors Q1 and Q2 connected in parallel. The main signal input terminal G1 of transistor Q1 is connected to the discharge control output pin DO of the protection chip U2, and the main signal input terminal G1 of transistor Q2 is also connected to the discharge control output pin DO of the protection chip U2.

[0043] Specifically, the second protection module and the first protection module form a parallel redundant structure, and both independently monitor the cell status. When the protection chip U2 detects over-discharge or over-current, its discharge control output pin DO outputs a low level, driving transistors Q1 and Q2 to turn off, and simultaneously triggering the fuel gauge to enter sleep mode through diode D3.

[0044] Through the above technical solution, when a single protection module fails, another protection module can still trigger protection. For example, when the discharge control output pin DO of protection chip U1 is short-circuited to a high level, protection chip U2 can still independently turn off transistors Q1 and Q2 and put the fuel gauge into sleep mode. Specifically, protection chip U1 can be configured for fast response with a more lenient detection threshold, while protection chip U2 can be configured for slow response with a more stringent threshold, forming a graded protection gradient. Furthermore, the parallel structure of transistors Q1 and Q2 further reduces the on-resistance, improves the high-current discharge capability, and provides physical redundancy.

[0045] Example 3: The difference between this embodiment and embodiment 2 is that the resistance of resistor R18 in this embodiment is 2 megohms.

[0046] Specifically, resistor R18 is connected between the positive terminal of the battery cell and node 31 of the linkage unit. Under normal conditions, this node is biased to a high level, ensuring that the enable pin CE of the fuel gauge chip U3 remains valid. When any protection chip triggers a low-level protection output, the corresponding diode conducts, pulling the enable pin CE of the fuel gauge chip U3 low. At this time, resistor R18 acts as a high-resistance pull-up resistor, limiting reverse current and preventing interference with the protection chip output. In addition, the 2MΩ high resistance ensures that the leakage current through resistor R18 is extremely small during normal operation, and its impact on system power consumption is negligible.

[0047] This setting reduces the impact of external electromagnetic interference on the enable pin (CE) of the fuel gauge chip U3, ensuring stable operation of the fuel gauge. When the protection chip outputs a low level, resistor R18 and the diode form a voltage divider circuit, reliably pulling the enable pin (CE) of the fuel gauge chip U3 below the threshold. When the fuel gauge is in sleep mode, resistor R18 further limits leakage current, keeping the overall standby power consumption less than 1μA, effectively meeting long-term storage requirements.

[0048] In some embodiments, the fuel gauge chip U3 is either BQ27Z561 or SH366100G / 012GY. Preferably, the fuel gauge chip U3 is the AH17561 from Amperex Technology. Specifically, this type of chip uses the Impedance Tracking™ algorithm to calculate the remaining capacity (SOC) and state of health (SOH) in real time by monitoring battery voltage, current integral, and temperature, with an accuracy of ±1%. When the fuel gauge chip U3 enters sleep mode, the operating current drops from the normal 30μA to less than 1μA, retaining only basic timing functions. Additionally, it communicates with the main controller via the I²C / SMBus interface, outputting data such as battery level, voltage, and temperature, supporting dynamic updates of battery information.

[0049] In some embodiments, the protection chip U1 is model number Zhongying SH366302R5 / 006R5Y / BAT00. The protection chip U2 is also model number Zhongying SH366302R5 / 006R5Y / BAT00. This configuration provides multiple protection functions and high-precision voltage monitoring. It is AEC-Q100 Grade 1 certified, with a failure rate of less than 0.5 Fit, meeting automotive electronic reliability requirements. It also reduces battery self-discharge rate and improves storage life. Furthermore, its built-in digital filtering algorithm effectively suppresses false triggering caused by voltage fluctuations during battery charging and discharging, achieving a vibration resistance of 5G, ensuring that the protection chip U1 has good vibration resistance. This ensures the stability and reliability of the overall circuit design.

[0050] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0051] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this application is in use. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. In addition, the terms "first," "second," and "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0052] Furthermore, terms such as "horizontal," "vertical," and "sag" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0053] In this application, unless otherwise expressly specified and limited, "above or below" a first feature may include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on" a first feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" a first feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0054] Although the description of this application has been made in conjunction with the specific embodiments described above, it is obvious to those skilled in the art that many substitutions, modifications, and variations can be made based on the above description. Therefore, all such substitutions, modifications, and variations are included within the spirit and scope of the appended claims.

Claims

1. A battery protection circuit, characterized in that, include: The first protection control module has its input terminal connected to the positive terminal of the battery cell and its output terminal connected to the negative terminal of the battery cell. The second protection control module is connected in parallel with the first protection control module, and The metering module includes a fuel meter chip U3 and a linkage unit. The enable pin CE of the fuel meter chip U3 is connected to the linkage unit, and the linkage unit is connected to the first protection control module and the second protection control module respectively. The linkage unit is used to control the working state of the power meter chip U3 according to the high or low level of the first protection control module or the second protection control module.

2. The battery protection circuit according to claim 1, characterized in that, The linkage unit includes: Diode D4 has its cathode connected to the discharge output terminal of the first protection control module, and its anode connected to the enable pin CE of the fuel meter chip U3 through resistor R7. Diode D3, its cathode is connected to the discharge output terminal of the second protection control module, and its anode is connected to the anode of diode D4; and Resistor R18, one end of which is connected to the anode of diode D4 and the anode of diode D3, and the other end of resistor R18 is connected to the positive terminal of the battery cell.

3. The battery protection circuit according to claim 1, characterized in that, The first protection control module includes a protection chip U1 and a first power switch unit. The positive power supply pin VDD of the protection chip U1 is connected to the positive terminal of the battery cell, and the discharge control output pin DO of the protection chip U1 is connected to the linkage unit. The input terminal of the first power switch unit is connected to the discharge control output pin DO of the protection chip U1, and the output terminal of the first power switch is connected to the negative terminal of the battery cell.

4. The battery protection circuit according to claim 3, characterized in that, The first power switching power supply includes transistors Q3 and Q4 connected in parallel. The main signal input terminal G1 of transistor Q3 is connected to the discharge control output pin DO of the protection chip U1, and the main signal input terminal G1 of transistor Q4 is connected to the discharge control output pin DO of the protection chip U1.

5. The battery protection circuit according to claim 1, characterized in that, The second protection control module includes a protection chip U2 and a second power switch unit. The positive power supply pin VDD of the protection chip U2 is connected to the positive terminal of the battery cell, and the discharge control output pin DO of the protection chip U2 is connected to the linkage unit. The input terminal of the second power switch unit is connected to the discharge control output pin DO of the protection chip U2, and the output terminal of the second power switch is connected to the negative terminal of the battery cell.

6. The battery protection circuit according to claim 5, characterized in that, The second power switching power supply includes transistors Q1 and Q2 connected in parallel. The main signal input terminal G1 of transistor Q1 is connected to the discharge control output pin DO of the protection chip U2, and the main signal input terminal G1 of transistor Q2 is connected to the discharge control output pin DO of the protection chip U2.

7. The battery protection circuit according to claim 2, characterized in that, The resistance of resistor R18 is 2 megohms.

8. The battery protection circuit according to claim 1, characterized in that, The power meter chip U3 is either model BQ27Z561 or SH366100G / 012GY.

9. The battery protection circuit according to claim 3, characterized in that, The protection chip U1 is model number Zhongying SH366302R5 / 006R5Y / BAT00.

10. The battery protection circuit according to claim 5, characterized in that, The protection chip U2 is model number Zhongying SH366302R5 / 006R5Y / BAT00.

Images