Lithium battery protection circuit
The lithium battery protection circuit, which combines voltage dividers and current limiters, solves the problem of lithium batteries failing to function properly on their first power-on, achieving low power consumption and safe plug-and-play functionality, and improving the stability and safety of portable lithium battery devices.
Patent Information
- Application Number
- CN202520385068.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-06
- Publication Date
- 2026-02-17
- Estimated Expiration
- 2035-03-06
AI Technical Summary
Existing single-cell lithium battery protection circuits may fail to enter normal mode upon first power-on, resulting in the battery failing to discharge and posing risks such as overheating, excessively long charging times, shortened battery life, or even explosion.
The lithium battery protection circuit uses a combination of voltage dividers and current limiters. It triggers the chip detection with a small current to achieve plug-and-play functionality, prevents overcurrent damage to the internal circuit, and simplifies component combination to achieve low power consumption and stable detection.
It achieves a balance between low-power wake-up, stable detection, and security protection, making it suitable for portable lithium battery devices, improving system robustness, and avoiding startup delays caused by chip hibernation.
Smart Images
Figure CN223928084U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of lithium battery protection technology, and in particular to a lithium battery protection circuit. Background Technology
[0002] During charging, the voltage of a lithium battery gradually increases. If the voltage reaches a safe threshold and the power is not cut off in time, it can lead to overheating, excessively long charging time, shortened battery life, or even explosion. Similarly, during discharging, the voltage gradually decreases. If the voltage drops below a safe threshold and discharging is not stopped, it can lead to depletion of battery power, shortened lifespan, or even inability to recharge.
[0003] The existing single-cell lithium battery protection circuit has the following defect: when the battery is first connected to the protection circuit, the circuit may not enter the normal mode, and it will be unable to discharge. Utility Model Content
[0004] In view of this, the purpose of this utility model is to propose a lithium battery protection circuit to solve the problems mentioned in the background art.
[0005] To achieve the above objectives, this utility model provides a lithium battery protection circuit, comprising: a first voltage divider, a second voltage divider, a third voltage divider, a first current limiter, a second current limiter, and an integrated circuit U8;
[0006] Pin 1 of the integrated circuit U8 is connected to the second current limiting component and then grounded; the first voltage divider and the third voltage divider are connected in parallel, and pin 1 of the integrated circuit U8 is also connected to the first voltage divider and the third voltage divider and then connected to the negative terminal of the battery; pin 1 of the integrated circuit U8 is also connected to the second voltage divider and then connected to the positive terminal of the battery; pin 2 of the integrated circuit U8 is grounded; pin 3 of the integrated circuit U8 is connected to the negative terminal of the battery; pin 5 of the integrated circuit U8 is connected to the first current limiting component; pin 6 of the integrated circuit U8 is connected to capacitor C33 and then connected to the first current limiting component; the first current limiting component is connected to the positive terminal of the battery; and capacitor C33 is connected to the negative terminal of the battery.
[0007] In one embodiment, the first voltage divider is a resistor R42, the second voltage divider is a resistor R44, the third voltage divider is a capacitor C21, the first current limiter is a resistor R52, and the second current limiter is a resistor R53.
[0008] As can be seen from the above, the lithium battery protection circuit provided by this utility model achieves a balance between low-power wake-up, stable detection, safety protection, and cost control with a simple combination of passive components. It is particularly suitable for portable lithium battery devices that are sensitive to space, power consumption, and cost. The voltage divider circuit composed of the first, second, and third voltage dividers triggers the chip detection (PIN1 of U8) with a small current, eliminating the need for an additional detection module with high power consumption. This saves energy and accurately wakes the chip into working condition. The first and second current limiters limit the maximum current flowing into the chip pins, preventing accidental overcurrent (such as transient impacts during insertion and removal) from damaging the internal circuitry of the integrated circuit and improving system robustness. By simulating a charger insertion signal (small current trigger), the battery can still discharge normally when the charger is not connected, achieving "plug and play" functionality while avoiding startup delays caused by chip dormancy. Attached Figure Description
[0009] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0010] Figure 1 This is a schematic diagram of a conventional single-cell lithium battery circuit according to an embodiment of the present invention;
[0011] Figure 2 This is a schematic diagram of a lithium battery protection circuit according to an embodiment of the present invention. Detailed Implementation
[0012] Before describing the specific embodiments of this utility model, the overall concept of this utility model is explained as follows:
[0013] This utility model is mainly developed for the use of lithium batteries. Currently, most chip manufacturers' chips, such as... Figure 1 As shown, S1 and S2 need to be shorted or connected to the charger when powered on for the first time in order to enter normal mode.
[0014] Therefore, this utility model proposes a lithium battery protection circuit, which adds a resistor voltage divider circuit and uses the chip charger detection pin to detect the small current generated during the resistor voltage divider process, so that the lithium battery protection IC can enter the normal working mode upon initial power-on.
[0015] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to specific embodiments and accompanying drawings.
[0016] It should be noted that, unless otherwise defined, the technical or scientific terms used in the embodiments of this utility model should have the ordinary meaning understood by one of ordinary skill in the art to which this utility model pertains. The terms "first," "second," and similar terms used in this utility model do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are only used to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.
[0017] like Figure 2 As shown, this utility model proposes a lithium battery protection circuit, including: a first voltage divider, a second voltage divider, a third voltage divider, a first current limiter, a second current limiter, and an integrated circuit U8. The first voltage divider uses a resistor R42, the second voltage divider uses a resistor R44, the third voltage divider uses a capacitor C21, the first current limiter uses a resistor R52, and the second current limiter uses a resistor R53.
[0018] Pin 1 of integrated circuit U8 is connected to the second current limiter and then grounded.
[0019] The first, second, and third voltage dividers together form a voltage divider circuit, causing a small current to be detected on pin PIN1 of integrated circuit U8. The first and third voltage dividers are connected in parallel. Pin 1 of integrated circuit U8 is connected to the negative terminal of the battery after being connected to the first and third voltage dividers; pin 1 of integrated circuit U8 is connected to the positive terminal of the battery after being connected to the second voltage divider.
[0020] This invention adds a resistor voltage divider circuit, which uses the chip charger detection pin to detect the small current generated during the resistor voltage divider process, so that the lithium battery protection IC can enter normal working mode on the first power-on.
[0021] Pin 2 of integrated circuit U8 is grounded.
[0022] Pin 3 of integrated circuit U8 is connected to the negative terminal of the battery.
[0023] Pin 5 of integrated circuit U8 is connected to the first current limiting component; pin 6 of integrated circuit U8 is connected to capacitor C33 and then to the first current limiting component; the first current limiting component is connected to the positive terminal of the battery; capacitor C33 is connected to the negative terminal of the battery.
[0024] When the battery is connected, the first, second, and third voltage dividers form a circuit. The PIN1 pin of the integrated circuit U8 will detect a small current. At this time, the chip will think that a charger is connected, thus mistakenly thinking that it has entered charging mode, opening the internal circuit of the chip, making the chip work normally, and the battery will start to discharge normally.
[0025] This utility model provides a lithium battery protection circuit that achieves a balance between low-power wake-up, stable detection, safety protection, and cost control through a simple combination of passive components. It is particularly suitable for portable lithium battery devices sensitive to space, power consumption, and cost. The voltage divider circuit, composed of a first, second, and third voltage divider, triggers chip detection (PIN1 of U8) with a small current, eliminating the need for an additional high-power detection module. This saves energy and accurately wakes the chip into working condition. The first and second current limiters restrict the maximum current flowing into the chip pins, preventing accidental overcurrent (such as transient impacts during insertion and removal) from damaging the internal circuitry of the integrated circuit and improving system robustness. By simulating a charger insertion signal (small current trigger), the battery can still discharge normally when no charger is connected, achieving "plug and play" functionality while avoiding startup delays caused by chip dormancy.
[0026] 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, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the present invention as described above, which are not provided in the details for the sake of brevity.
[0027] The embodiments of this utility model are intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.
Claims
1. A lithium battery protection circuit, characterized by, Comprise: The first voltage divider, the second voltage divider, the third voltage divider, the first current limiting piece, the second current limiting piece and integrated circuit U8; The 1 pin of the integrated circuit U8 is connected with the second current limiting piece and then grounded; the first voltage divider and the third voltage divider are connected in parallel, the 1 pin of the integrated circuit U8 is also connected with the first voltage divider and the third voltage divider and then connected with the negative electrode of the battery; the 1 pin of the integrated circuit U8 is also connected with the second voltage divider and then connected with the positive electrode of the battery; the 2 pin of the integrated circuit U8 is grounded; the 3 pin of the integrated circuit U8 is connected with the negative electrode of the battery; the 5 pin of the integrated circuit U8 is connected with the first current limiting piece; the 6 pin of the integrated circuit U8 is connected with the capacitor C33 and then connected with the first current limiting piece; the first current limiting piece is connected with the positive electrode of the battery; the capacitor C33 is connected with the negative electrode of the battery.
2. A protection circuit for a lithium battery as defined in claim 1, characterized in that The first voltage divider adopts the resistor R42, the second voltage divider adopts the resistor R44, the third voltage divider adopts the capacitor C21, the first current limiting piece adopts the resistor R52, and the second current limiting piece adopts the resistor R53.