A single lithium ion protection circuit with all-around secondary protection realized by parallel ICs

Abstract

This invention provides a single-cell lithium-ion battery protection circuit with parallel ICs for comprehensive secondary protection, relating to the field of single-cell lithium-ion battery protection. The circuit includes a primary protection unit and a secondary protection unit, which operate in parallel and control the battery's charging and discharging circuits using field-effect transistor switching elements. This parallel IC-based single-cell lithium-ion battery protection circuit provides comprehensive secondary protection against overcharge, over-discharge, overcurrent, and temperature even in the event of primary protection failure, significantly improving the safety and reliability of lithium-ion battery packs. The circuit design is simple, highly reliable, and suitable for various single-cell lithium-ion battery protection applications, enhancing battery safety and reliability.

Description

Technical Field

[0001] This utility model relates to the field of single-cell lithium-ion battery protection, and in particular to a single-cell lithium-ion battery protection circuit that uses parallel ICs to achieve comprehensive secondary protection. Background Technology

[0002] With the widespread use of lithium-ion batteries in electronic products, battery safety has become an increasingly important concern. Currently, most single-cell lithium battery protection circuits on the market rely primarily on primary protection ICs (such as FUSE, PTC, etc.) to provide basic protection against overcharge, over-discharge, and overcurrent, typically offering only single protection functions. However, these solutions usually offer limited protection and lack protection against factors such as temperature. Therefore, if the main protection IC fails or malfunctions, the lithium battery is prone to overcharging, over-discharging, or overcurrent, leading to battery damage or even safety accidents.

[0003] More importantly, most existing single-cell lithium-ion battery protection circuits on the market lack temperature protection, and abnormal temperatures are a significant factor contributing to battery safety issues. Therefore, it is essential to design a secondary protection circuit that can still provide comprehensive protection even in the event of a primary protection failure. Utility Model Content

[0004] In view of this, the purpose of this utility model is to propose a single-cell lithium-ion protection circuit that achieves comprehensive secondary protection through parallel ICs. In particular, based on the relatively one-sided secondary protection technology in the existing market, by applying parallel integrated circuits (ICs), a complete secondary protection system is formed, including overcharge, over-discharge, overcurrent, and temperature protection. Even if the primary protection fails, the secondary protection circuit can continue to provide comprehensive protection for the battery, thereby improving the safety and reliability of the battery.

[0005] To achieve the above objectives, this utility model provides the following technical solution:

[0006] Based on the above objectives, this utility model provides a single-cell lithium-ion protection circuit that achieves comprehensive secondary protection through parallel ICs, including a primary protection unit and a secondary protection unit. The primary protection unit and the secondary protection unit operate in parallel and control the battery charging and discharging circuits respectively through field-effect transistor switching elements.

[0007] As a further embodiment of this utility model, the primary protection unit includes a primary protection IC (U2). The VDD pin of the primary protection IC (U2) is connected to the positive terminal (B+) of the battery through a resistor R2 and a capacitor C2. The CS pin of the primary protection IC (U2) is connected to the negative terminal (B-) of the battery through a resistor R4. The output pin of the primary protection IC (U2) is connected to a field-effect transistor (Q2) for protection.

[0008] As a further embodiment of this invention, the gate (G1) of the field-effect transistor (Q2) is connected to the primary protection IC (U2). When the battery voltage or current is abnormal, the primary protection IC (U2) controls the field-effect transistor (Q2) to turn off, thereby achieving protection.

[0009] As a further embodiment of this utility model, the primary protection unit further includes capacitors C4 and C6, which are filter capacitors used to suppress high-frequency noise in the circuit.

[0010] As a further embodiment of this utility model, the secondary protection unit includes a secondary protection IC (U1). The VDD pin of the secondary protection IC (U1) is connected to the positive terminal (B+) of the battery through a resistor R1 and a capacitor C1, and is connected to the negative terminal (B-) of the battery through a current detection resistor R6.

[0011] As a further embodiment of this invention, the secondary protection unit also includes an NTC thermistor (RT). The NTC thermistor (RT) is connected to the TH pin of the secondary protection IC (U1) and is used to detect the surface temperature of the battery. If the temperature reaches the protection threshold, the secondary protection IC (U1) controls the connected field-effect transistor (Q1) to turn off, thereby achieving temperature protection.

[0012] As a further embodiment of this invention, the secondary protection IC (U1) achieves overcurrent protection by monitoring the voltage drop across the current sensing resistor R6. When the primary protection fails, U1 detects the current and temperature status and controls Q1 to disconnect the battery's charging and discharging circuit, thus achieving secondary protection. The overcurrent protection threshold can be adjusted by changing the resistance value of R6.

[0013] As a further embodiment of this utility model, the secondary protection unit also includes a resistor R5 and a capacitor C5. The resistor R5 is connected to the CO pin of the secondary protection IC (U1) and is used to stabilize the control signal. The capacitor C5 is a filter capacitor used to suppress high-frequency noise in the circuit.

[0014] As a further embodiment of this invention, the field-effect transistor (Q1) and the field-effect transistor (Q2) are MOSFETs of model CJCD2005.

[0015] As a further embodiment of this utility model, the discharge overcurrent of the primary protection unit is a detection voltage of 60-90mV, an internal resistance of 15-29mΩ, a detection current of 2-6A, and a delay of 9-12-15ms.

[0016] The charging overcurrent protection unit has the following parameters: detection voltage 80-120mV, internal resistance 15-29mΩ, detection current 2.7-8A, and delay 6-8-10ms.

[0017] The overvoltage during charging of the primary protection unit is 4.280±0.025V; the undervoltage during discharging is 3.000±0.050V.

[0018] As a further embodiment of this utility model, the discharge overcurrent of the secondary protection unit is a detection voltage of 25.5-28.5mV, an internal resistance of 7.82-8.08mΩ, and a detection current of 3.0-3.6A.

[0019] The charging overcurrent protection unit has the following parameters: detection voltage 19.5-22.5mV, internal resistance 7.82-8.08mΩ, and detection current 2.4-2.9A.

[0020] The charging overvoltage of the secondary protection unit is 4.500±0.015V; the discharging undervoltage is 2.500±0.050V; and charging is prohibited at 0V: 0.6-1.5V.

[0021] Compared with existing technologies, the single-cell lithium-ion protection circuit proposed in this utility model, which uses parallel ICs to achieve comprehensive secondary protection, has the following advantages:

[0022] 1. Enhanced Battery Safety: This invention employs a dual protection design with a primary protection IC (U2) and a secondary protection IC (U1), effectively addressing various battery fault scenarios such as overcharging, over-discharging, overcurrent, and abnormal temperature. The primary protection provides basic voltage, current, and over-discharge protection, while the secondary protection takes over in case the primary protection fails, further ensuring battery safety and avoiding the risks associated with the failure of a single protection system. This redundant design significantly improves battery safety under various fault conditions.

[0023] 2. Overcurrent and Temperature Protection: This single-cell lithium-ion protection circuit not only provides overcurrent protection through the current sensing resistor (R6), but also monitors the battery temperature in real time using an NTC thermistor (RT). Once an overcurrent or abnormal battery temperature (too high or too low) is detected, the secondary protection IC (U1) controls the MOSFET (Q1) to disconnect the battery charging / discharging circuit, preventing damage from overcurrent or overtemperature. This significantly improves battery safety in extreme environments and reduces the risk of accidents such as fires and explosions.

[0024] 3. Improved Battery Life: The overcharge, over-discharge, and overcurrent protection in this invention helps prevent over-discharge or over-charge of the battery, effectively extending its lifespan. By monitoring current, voltage, and temperature in real time, the circuit can intelligently adjust the protection threshold, reducing battery aging or damage caused by improper use. Furthermore, by using capacitors (C4, C5, C6) to filter high-frequency noise in the circuit, the circuit's stability is ensured under various operating environments. Even in the presence of electromagnetic interference (EMI) or high-frequency noise, the circuit can still accurately protect the battery, avoiding false triggering or protection function failure.

[0025] 4. This utility model's single-cell lithium-ion protection circuit achieves integrated secondary protection functions through parallel IC connection, reducing the number of components and circuit complexity. While maintaining high reliability and multiple protections, it reduces the overall design complexity and component cost of the protection circuit. This design provides manufacturers with a simplified solution, reduces production costs, and is easy to integrate into different types of lithium-ion battery protection boards. This utility model's single-cell lithium-ion protection circuit is suitable for various application scenarios of single-cell lithium-ion batteries, especially in consumer electronics, power tools, electric vehicles, and energy storage systems. By adjusting the current sensing resistor (R6) and the operating parameters of the protection IC, users can customize the circuit according to different battery specifications and operating environments to meet diverse needs.

[0026] 5. Enhanced system fault tolerance: In traditional battery protection designs, the primary protection IC (such as overcharge protection) is usually the only protection method, and its failure may lead to battery damage. However, the single-cell lithium-ion protection circuit of this invention connects a secondary protection IC (U1) in parallel. Even if the primary protection IC fails, the secondary protection IC can still continue to protect the battery, effectively increasing the fault tolerance and reliability of the battery protection system.

[0027] In summary, this invention, through the parallel use of primary and secondary protection ICs, precise current and temperature monitoring mechanisms, reasonable noise suppression design, and simplified circuit structure, not only improves the safety, reliability, and applicability of battery protection circuits, but also effectively extends battery life, reduces production costs, and greatly enhances the overall performance and safety of lithium-ion batteries in practical applications.

[0028] These or other aspects of this application will become more apparent from the following description of embodiments. It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only, and are not intended to limit the application. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of this utility model or related technologies, the accompanying drawings used in the description of the exemplary embodiments or related technologies will be briefly introduced below. The drawings are used to provide a further understanding of this utility model and constitute a part of the specification. They are used together with the embodiments of this utility model to explain this utility model and do not constitute a limitation on this utility model. In the drawings:

[0030] Figure 1 This is a circuit diagram of a single-cell lithium-ion protection circuit that uses a parallel IC to achieve comprehensive secondary protection, according to an embodiment of this utility model. Detailed Implementation

[0031] The present application will now be further described in conjunction with the accompanying drawings and specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.

[0032] To make the objectives, technical solutions, and advantages of this utility model clearer, the embodiments of this utility model are further described in detail below with reference to specific examples and the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit this application.

[0033] It should be noted that all uses of the terms "first" and "second" in the embodiments of this utility model are for the purpose of distinguishing two different entities or different parameters with the same name. Therefore, "first" and "second" are merely for convenience of expression and should not be construed as limiting the embodiments of this utility model. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion, such as other steps or units inherent in a process, method, system, product, or device that includes a series of steps or units.

[0034] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0035] The flowchart shown in the attached diagram is for illustrative purposes only and does not necessarily include all content and operations / steps, nor does it necessarily have to be performed in the order described. For example, some operations / steps can be broken down, combined, or partially merged, so the actual execution order may change depending on the actual situation.

[0036] The following detailed description of some embodiments of this application is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0037] See Figure 1 As shown, an embodiment of this utility model provides a single-cell lithium-ion protection circuit that achieves comprehensive secondary protection through parallel ICs, including a primary protection unit and a secondary protection unit. The primary protection unit and the secondary protection unit operate in parallel and control the battery charging and discharging circuits respectively through field-effect transistor switching elements.

[0038] In this embodiment, the primary protection unit includes a primary protection IC (U2). The VDD pin of the primary protection IC (U2) is connected to the positive terminal (B+) of the battery through a resistor R2 and a capacitor C2. The CS pin of the primary protection IC (U2) is connected to the negative terminal (B-) of the battery through a resistor R4. The output pin of the primary protection IC (U2) is connected to a field-effect transistor (Q2) for protection.

[0039] The gate (G1) of the field-effect transistor (Q2) is connected to the primary protection IC (U2). When the battery voltage or current is abnormal, the primary protection IC (U2) controls the field-effect transistor (Q2) to turn off to achieve protection. The primary protection unit also includes capacitors C4 and C6, which are filter capacitors used to suppress high-frequency noise in the circuit.

[0040] In this embodiment, the discharge overcurrent of the primary protection unit is a detection voltage of 60-90mV, an internal resistance of 15-29mΩ, a detection current of 2-6A, and a delay of 9-12-15ms.

[0041] The charging overcurrent protection unit has the following parameters: detection voltage 80-120mV, internal resistance 15-29mΩ, detection current 2.7-8A, and delay 6-8-10ms.

[0042] The overvoltage during charging of the primary protection unit is 4.280±0.025V; the undervoltage during discharging is 3.000±0.050V.

[0043] In this embodiment, the secondary protection unit includes a secondary protection IC (U1). The VDD pin of the secondary protection IC (U1) is connected to the positive terminal (B+) of the battery through a resistor R1 and a capacitor C1, and is connected to the negative terminal (B-) of the battery through a current sensing resistor R6.

[0044] The secondary protection unit also includes an NTC thermistor (RT), which is connected to the TH pin of the secondary protection IC (U1) to detect the battery surface temperature. If the temperature reaches the protection threshold, the secondary protection IC (U1) controls the connected field-effect transistor (Q1) to turn off, thereby achieving temperature protection.

[0045] This invention's single-cell lithium-ion protection circuit not only achieves overcurrent protection through a current-sensing resistor (R6), but also monitors the battery temperature in real time using an NTC thermistor (RT). Once an overcurrent or abnormal battery temperature (too high or too low) is detected, the secondary protection IC (U1) controls the MOSFET (Q1) to disconnect the battery charging and discharging circuit, preventing damage to the battery from overcurrent or overtemperature. This significantly improves battery safety in extreme environments, reducing the risk of accidents such as fires and explosions.

[0046] The secondary protection IC (U1) implements overcurrent protection by monitoring the voltage drop across the current sensing resistor R6. When the primary protection fails, U1 detects the current and temperature status and controls Q1 to disconnect the battery's charging and discharging circuit, thus implementing secondary protection. The overcurrent protection threshold can be adjusted by changing the resistance value of R6. The secondary protection unit also includes a resistor R5 and a capacitor C5. Resistor R5 is connected to the CO pin of the secondary protection IC (U1) to stabilize the control signal; capacitor C5 is a filter capacitor used to suppress high-frequency noise in the circuit.

[0047] This invention provides overcharge, over-discharge, and overcurrent protection for the battery, helping to prevent over-discharge or over-charge and effectively extending battery life. By monitoring current, voltage, and temperature in real time, the circuit can intelligently adjust the protection threshold, reducing battery aging or damage caused by improper use. Furthermore, capacitors (C4, C5, C6) are used to filter high-frequency noise in the circuit, ensuring its stability under various operating environments. Even in the presence of electromagnetic interference (EMI) or high-frequency noise, the circuit can still accurately protect the battery, avoiding false triggering or protection failure.

[0048] In this embodiment, the discharge overcurrent of the secondary protection unit is a detection voltage of 25.5-28.5mV, an internal resistance of 7.82-8.08mΩ, and a detection current of 3.0-3.6A.

[0049] The charging overcurrent protection unit has the following parameters: detection voltage 19.5-22.5mV, internal resistance 7.82-8.08mΩ, and detection current 2.4-2.9A.

[0050] The charging overvoltage of the secondary protection unit is 4.500±0.015V; the discharging undervoltage is 2.500±0.050V; and charging is prohibited at 0V: 0.6-1.5V.

[0051] In this embodiment, the field-effect transistors (Q1) and (Q2) are MOSFETs of model CJCD2005.

[0052] This invention employs a dual protection design with a primary protection IC (U2) and a secondary protection IC (U1), effectively addressing various battery fault scenarios such as overcharging, over-discharging, overcurrent, and abnormal temperature. The primary protection provides basic voltage, current, and over-discharge protection, while the secondary protection takes over in case the primary protection fails, further ensuring battery safety and avoiding the risks associated with the failure of a single protection system. This redundant design significantly enhances battery safety under various fault conditions.

[0053] In this invention, the primary protection IC (U2) uses the HY2113-GH3A chip. The primary protection IC (U2) is a full-function lithium battery protection IC providing first-level overcharge, over-discharge, and overcurrent protection. The secondary protection IC (U1) uses the S82D1AAE chip, a lithium-ion protection IC that, in addition to basic lithium battery protection functions such as overcharge and over-discharge, also features active temperature protection. Using the secondary protection IC (U1) as the secondary protection IC, when the primary protection IC (U2) and the field-effect transistor (Q2) fail due to uncontrollable factors, the secondary protection circuit, composed of the secondary protection IC (U1), the field-effect transistor (Q1), the NTC thermistor (RT), and resistor R6, will activate. Even in the event of a primary protection failure, the secondary protection IC (U1) can still detect the battery status and monitor the current magnitude through the detection resistor when an abnormal current occurs. When the protection threshold is reached, it shuts off the secondary protection MOS, thus achieving secondary protection after a primary failure. This IC also features temperature protection. In summary, the NTC thermistor (RT) detects the surface temperature of the battery cell, and controls the MOS to turn off when the temperature reaches the protection threshold.

[0054] This invention presents a single-cell lithium-ion protection circuit that integrates two-stage protection functions through a parallel IC configuration, reducing the number of components and circuit complexity. While maintaining high reliability and multiple protections, it lowers the overall design complexity and component costs of the protection circuit. This design provides manufacturers with a simplified solution, reduces production costs, and is easily integrated into different types of lithium-ion battery protection boards. This single-cell lithium-ion protection circuit is suitable for various applications of single-cell lithium-ion batteries, especially in consumer electronics, power tools, electric vehicles, and energy storage systems. By adjusting the current sensing resistor (R6) and the operating parameters of the protection IC, users can customize the circuit according to different battery specifications and operating environments to meet diverse needs.

[0055] In summary, this invention, through the parallel use of primary and secondary protection ICs, precise current and temperature monitoring mechanisms, reasonable noise suppression design, and simplified circuit structure, not only improves the safety, reliability, and applicability of battery protection circuits, but also effectively extends battery life, reduces production costs, and greatly enhances the overall performance and safety of lithium-ion batteries in practical applications.

[0056] The above are exemplary embodiments disclosed in this utility model. However, it should be noted that various changes and modifications can be made without departing from the scope of the embodiments of this utility model as defined by the claims. The functions, steps, and / or actions of the methods according to the disclosed embodiments described herein do not need to be performed in any particular order. Furthermore, although the elements disclosed in the embodiments of this utility model may be described or claimed individually, they may be understood as multiple unless explicitly limited to a singular number.

[0057] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the present invention (including the claims) is limited to these examples. Within the framework of the present invention, technical features of the above embodiments or different embodiments can also be combined, and many other variations of different aspects of the present invention exist, which are not provided in the details for the sake of brevity. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A single lithium-ion protection circuit with full protection implemented in parallel ICs, characterized in that, It includes a primary protection unit and a secondary protection unit, which work in parallel and control the battery charging and discharging circuits respectively through field-effect transistor switching elements; The primary protection unit includes a primary protection IC. The VDD pin of the primary protection IC is connected to the positive terminal B+ of the battery through resistor R2 and capacitor C2. The CS pin of the primary protection IC is connected to the negative terminal B- of the battery through resistor R4. The output pin of the primary protection IC is connected to the field-effect transistor Q2 for protection. The gate G1 of the field-effect transistor Q2 is connected to the primary protection IC. When the battery voltage or current is abnormal, the primary protection IC controls the field-effect transistor Q2 to turn off. The primary protection unit also includes capacitors C4 and C6, which are filter capacitors. The secondary protection unit includes a secondary protection IC. The VDD pin of the secondary protection IC is connected to the positive terminal B+ of the battery through resistor R1 and capacitor C1, and to the negative terminal B- of the battery through current sensing resistor R6. The secondary protection unit also includes an NTC thermistor, which is connected to the TH pin of the secondary protection IC and is used to detect the surface temperature of the battery. If the temperature reaches the protection threshold, the secondary protection IC controls the connected field-effect transistor Q1 to turn off, thereby achieving temperature protection. The secondary protection unit also includes a resistor R5 and a capacitor C5. Resistor R5 is connected to the CO pin of the secondary protection IC. Capacitor C5 is a filter capacitor for suppressing high-frequency noise in the circuit. The primary protection IC uses the HY2113-GH3A chip, which is a full-function lithium battery protection IC that provides first-level overcharge, over-discharge, and overcurrent protection. The secondary protection IC uses the S82D1AAE chip, which is a lithium-ion protection IC for overcharge, over-discharge, and active temperature protection. The field-effect transistors Q1 and Q2 are MOSFETs of model CJCD2005.

2. The single-cell Li-ion protection circuit with full-featured two-level protection implemented in parallel ICs as claimed in claim 1, wherein, The discharge overcurrent of the primary protection unit is a detection voltage of 60-90mV, an internal resistance of 15-29mΩ, a detection current of 2-6A, and a delay of 9-12-15ms. The charging overcurrent protection unit has the following parameters: detection voltage 80-120mV, internal resistance 15-29mΩ, detection current 2.7-8A, and delay 6-8-10ms. The overvoltage during charging of the primary protection unit is 4.280±0.025V; the undervoltage during discharging is 3.000±0.050V.

3. The single-cell Li-ion protection circuit with full-featured two-level protection implemented in parallel ICs as claimed in claim 1, wherein, The discharge overcurrent protection unit has a detection voltage of 25.5-28.5mV, an internal resistance of 7.82-8.08mΩ, and a detection current of 3.0-3.6A. The charging overcurrent protection unit has the following parameters: detection voltage 19.5-22.5mV, internal resistance 7.82-8.08mΩ, and detection current 2.4-2.9A. The charging overvoltage of the secondary protection unit is 4.500±0.015V; the discharging undervoltage is 2.500±0.050V; and charging is prohibited at 0V: 0.6-1.5V.

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