Lithium battery protection circuit and lithium battery

Abstract

The utility model provides a lithium battery protection circuit, a lithium battery, a major loop, a first protection circuit, a second protection circuit and an electric quantity metering circuit, the first protection circuit comprises a first protection switch and a first resistor module, and the second protection circuit comprises a second protection switch and a second resistor module. The electric quantity metering circuit is used for detecting the electric quantity and temperature of the battery cell. The problem that the service life of a battery is short due to the fact that the battery is prone to damage under the conditions of high temperature, high electric quantity and low electric quantity in the design of a charging circuit in the prior art is solved. Through protection of the high-temperature high-electric-quantity protection circuit and the low-electric-quantity protection circuit, overlarge electric quantity during charging and discharging of the battery is effectively prevented, and damage of overlarge current or overlow electric quantity to the battery core is reduced, so that the service life of the battery is prolonged.

Description

Technical Field

[0001] The utility model relates to the field of lithium battery charging protection, in particular to a lithium battery protection circuit and a lithium battery. Background Art

[0002] With the rapid development of the times, energy storage technology has developed to date. In response to different fields and different needs, people have proposed and developed a variety of energy storage technologies to meet applications. Compared with other commercial rechargeable batteries, lithium batteries have the advantages of high energy density, long cycle life, wide operating temperature range and safety and reliability. It is currently the most feasible technical route for the development of energy storage products.

[0003] However, in recent years, lithium batteries used by some mobile phone brands and automobile brands have experienced natural explosions. The reasons can be divided into three types: the first is external short circuit, the second is internal short circuit and the third is overcharging. The first two are caused by poor design of the lithium battery itself, while the third is caused by substandard charger quality. Therefore, there is an urgent need to study technologies that improve the safety of battery design.

[0004] The existing lithium-ion battery protection circuit in the current prior art only includes a primary protection circuit, a secondary protection circuit and a power metering circuit; it lacks protection for the battery under high temperature, high power and low power conditions. When the battery is under high temperature, high power and low power with load, the battery cell will be damaged to a certain extent, resulting in a short battery life. Utility Model Content

[0005] Based on the above problems, the utility model proposes a lithium battery protection circuit and a lithium battery to solve the problem that the current prior art design of the charging circuit lacks consideration of the battery being easily damaged under high temperature, high power and low power conditions, resulting in a short battery life.

[0006] To achieve the above-mentioned purpose, the embodiment of the utility model provides a lithium battery protection circuit and a lithium battery, comprising: a main circuit, a first protection circuit, a second protection circuit and an electric quantity metering circuit; wherein the main circuit comprises a positive side circuit and a negative side circuit for connecting the positive and negative ends of the battery cell;

[0007] The first protection circuit includes: a first protection switch and a first resistance module; the first control end of the first protection switch is connected to the power metering circuit, the first connection end of the first protection switch is connected to the negative electrode side line, and the second connection end of the first protection switch is connected to the first resistance module;

[0008] The second protection circuit includes: a second protection switch and a second resistance module; the first control end of the second protection switch is connected to the power metering circuit, the first connection end of the second protection switch is connected to the positive side line through the second resistance module, and the second connection end of the second protection switch is grounded;

[0009] The power metering circuit is used to detect the power and temperature of the battery cell, wherein the first pin, the second pin and the third pin of the power metering circuit are respectively connected to the positive side circuit, and the temperature detection pin of the power metering circuit is connected to the temperature sensor module.

[0010] The utility model adds a first protection circuit and a second protection circuit, and detects the battery cell power and temperature according to the power metering circuit. Under high temperature and high power conditions, the discharge circuit composed of the first protection switch and the first resistor module is shunted, and the current of the main circuit is limited to discharge with a smaller current, and cannot discharge with a large current; under low power conditions, the discharge circuit composed of the second protection switch and the second resistor module forms a discharge barrier to prevent excessive discharge of the battery under low power conditions, thereby protecting the battery, and the current of the main circuit is affected to a certain extent and cannot discharge with a larger current under low power conditions. Through the protection of the first protection circuit and the second protection circuit, the battery is effectively prevented from being overcharged during charging and discharging, and the damage to the battery cell caused by excessive current or too low power is reduced, thereby improving the battery life.

[0011] Furthermore, the lithium battery protection circuit further includes: a third protection circuit;

[0012] The third protection circuit comprises: a first protection IC and a first main loop protection MOS;

[0013] The first protection IC and the first main circuit protection MOS are connected in series;

[0014] One end of the first protection IC is connected to the positive side line of the main circuit through the second resistor module, and the first protection IC is used to monitor the battery status, overcharge and overdischarge protection, and overcurrent protection;

[0015] The first main circuit protection MOS includes a plurality of MOS tube groups, and the first main circuit protection MOS is used for battery reverse protection.

[0016] Furthermore, the first protection switch is composed of a plurality of MOS tubes, and the first protection switch is used to control the on and off of the first protection circuit;

[0017] The first resistance module is composed of a plurality of resistors connected in series, and is used for shunting and limiting the discharge capacity of the main circuit.

[0018] Furthermore, the second protection switch is composed of a plurality of MOS tubes, and the second protection switch is used to control the on and off of the second protection circuit;

[0019] The second resistance module is composed of a plurality of resistors, and is used for shunting and limiting the discharge capacity of the main circuit and protecting the circuit.

[0020] Furthermore, the main circuit of the lithium battery protection circuit further includes: a third resistance module;

[0021] The third resistor module is connected to the first resistor module, and the connection circuit between the third resistor module and the first resistor module is used to shunt and limit the discharge capacity of the main circuit;

[0022] The third resistance module is connected to the electric quantity measurement circuit, and the connection circuit between the third resistance module and the electric quantity measurement circuit is used to select or activate each protection module.

[0023] Furthermore, the third resistor module is composed of a plurality of current-sensing precision resistors.

[0024] Furthermore, the power metering circuit further includes: a third protection IC;

[0025] The third protection IC includes: a first control pin and a second control pin;

[0026] The first control pin is used to output a high level to control the first protection circuit to be turned on when the power of the main circuit is greater than a preset required range;

[0027] The second control pin is used to output a high level to control the second protection circuit to be turned on when the power of the main circuit is less than the preset requirement range.

[0028] Furthermore, the lithium battery protection circuit further comprises:

[0029] A number of capacitors and a number of resistors;

[0030] The plurality of capacitors and the plurality of resistors are used to protect the circuit.

[0031] The utility model also provides a lithium battery in which the lithium battery protection circuit is arranged.

[0032] The utility model proposes a lithium battery, which adds a first protection circuit and a second protection circuit. Under high temperature and high power conditions, the first protection circuit is controlled to conduct and limit current. The current of the main circuit is limited and a small current can be discharged, but a large current cannot be discharged. Under low power conditions, the second protection circuit is controlled to limit current to prevent excessive discharge of the battery under low power conditions, thereby protecting the battery. The current of the main circuit is affected to a certain extent and a large current cannot be discharged under low power conditions. Through the protection of the first protection circuit and the second protection circuit, the battery is effectively prevented from being overcharged during charging and discharging, and the damage to the battery cell caused by excessive current or too low power is reduced, thereby improving the battery life. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 A schematic diagram of a module structure of a lithium battery protection circuit provided in a certain embodiment of the utility model;

[0034] Figure 2 A schematic diagram of a power metering circuit module structure of a lithium battery protection circuit provided in an embodiment of the utility model;

[0035] Figure 3 A schematic diagram of the structure of a third protection circuit module of a lithium battery protection circuit provided in a certain embodiment of the utility model;

[0036] Figure 4 A schematic diagram of a circuit connection structure of a lithium battery protection circuit provided in a certain embodiment of the utility model;

[0037] Figure 5 A schematic diagram of the circuit structure of a first protection module of a lithium battery protection circuit provided in one embodiment of the utility model;

[0038] Figure 6 A schematic diagram of the circuit structure of a first resistor module of a lithium battery protection circuit provided in one embodiment of the utility model;

[0039] Figure 7 A schematic diagram of the circuit structure of a second protection module of a lithium battery protection circuit provided in one embodiment of the utility model;

[0040] Figure 8 A schematic diagram of a third protection circuit structure of a lithium battery protection circuit provided in a certain embodiment of the utility model;

[0041] Fig. 9 A schematic diagram of a fourth protection circuit structure of a lithium battery protection circuit provided in a certain embodiment of the utility model;

[0042] Fig.10 A schematic diagram of the structure of a power metering circuit of a lithium battery protection circuit provided in a certain embodiment of the utility model. DETAILED DESCRIPTION

[0043] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0044] In this embodiment, according to Figure 4 The circuit connection structure shown is an example of an embodiment of the utility model, which also includes a fourth protection circuit having the same function as the third protection circuit.

[0045] It is worth mentioning that in the embodiments of the present utility model, all examples do not have any special limitations and only represent a feasible way of implementing the solution, which will not be described in detail below.

[0046] Example 1

[0047] At present, the lithium battery protection circuits on the market are mainly simple structures that only include primary protection circuits, secondary protection circuits and power metering circuits. Such structures cannot provide good protection when facing special situations such as overtemperature, overcharge and undercharge, which may damage the battery cells to a certain extent and shorten the battery life.

[0048] This embodiment uses a new type of lithium battery protection circuit for explanation, and adds a first protection circuit and a second protection circuit on the basis of the existing technology to make up for the shortcomings of the existing technology.

[0049] See also Figure 1 and Figure 2 , Figure 1 A schematic diagram of a module structure of a lithium battery protection circuit provided in a certain embodiment of the utility model; Figure 2 This is a schematic diagram of the structure of a power metering circuit module of a lithium battery protection circuit provided by a certain embodiment of the utility model. Figure 1 and Figure 2 As shown, the utility model proposes a lithium battery protection circuit, comprising: a main circuit 104, a first protection circuit 101, a second protection circuit 107 and an electric quantity metering circuit 1010; wherein the main circuit 104 comprises a positive side circuit 105 and a negative side circuit 106 for connecting the positive and negative ends of the battery cell;

[0050] The first protection circuit 101 includes: a first protection switch 102 and a first resistance module 103; the first control end of the first protection switch 102 is connected to the power metering circuit 1010, the first connection end of the first protection switch 102 is connected to the negative electrode side line 106, and the second connection end of the first protection switch 102 is connected to the first resistance module 103;

[0051] The second protection circuit 107 includes: a second protection switch 108 and a second resistance module 109; the first control end of the second protection switch 108 is connected to the power metering circuit 1010, the first connection end of the second protection switch 108 is connected to the positive side line 105 through the second resistance module 109, and the second connection end of the second protection switch 108 is grounded;

[0052] The power metering circuit 1010 is used to detect the power and temperature of the battery cell, wherein the first pin 205, the second pin 206 and the third pin 207 of the power metering circuit are respectively connected to the positive side line 105, and the temperature detection pin 209 of the power metering circuit is connected to the temperature sensor module 2011. As one possible implementation method: the first pin 205 of the power metering circuit can be a CE pin, which is used to control the enablement or disablement of the chip to control the working state of the chip; the second pin 206 of the power metering circuit can be a BAT_SNS pin, which is usually used to connect a battery status monitoring sensor to monitor the battery power, temperature, voltage and other parameters to achieve battery status monitoring and management; the third pin of the power metering circuit can be a BAT pin, which is usually used to connect a battery or a battery pack to provide power supply or charging function.

[0053] As an example of this embodiment, see Figure 3 and Figure 8 , Figure 3 A schematic diagram of the structure of a third protection circuit module of a lithium battery protection circuit provided by a certain embodiment of the utility model; see Figure 8 , Figure 8 The third protection circuit structure diagram of a lithium battery protection circuit provided by a certain embodiment of the utility model is shown in FIG. Figure 3 and Figure 8 As shown, the lithium battery protection circuit further includes: a third protection circuit 301;

[0054] The third protection circuit 301 includes: a first protection IC 302 and a first main loop protection MOS 303;

[0055] The first protection IC302 and the first main circuit protection MOS303 are connected in series;

[0056] One end of the first protection IC 302 is connected to the positive side line of the main circuit through the second resistor module 109, and the first protection IC is used to monitor the battery status, overcharge and overdischarge protection and overcurrent protection;

[0057] The first main circuit protection MOS 303 includes a plurality of MOS tube groups, and the first main circuit protection MOS 303 is used for battery reverse protection. One implementation method is: the first main circuit protection MOS 203 is obtained by connecting the first MOS tube group Q1 and the second MOS tube group Q2 in parallel.

[0058] As an example of this embodiment, see Figure 5 , Figure 5 This is a schematic diagram of the circuit structure of the first protection module of a lithium battery protection circuit provided by a certain embodiment of the utility model. Figure 5 As shown, the first protection switch 102 is composed of a plurality of MOS tubes, and the first protection switch 102 is used to control the on and off of the first protection circuit 101; one possible implementation method is: the first MOS tube M1, the first diode D3 and the first capacitor C16 constitute the first protection switch 102, the first control end of the first protection switch 102 is connected to the INT pin of the power metering circuit 1010, the first connection end of the first protection switch 102 is connected to the negative side line 106 of the main circuit 104, and the second connection end of the first protection switch 102 is connected to the first resistance module 103 through the DO end.

[0059] As another example of this embodiment, see Figure 6 , Figure 6 This is a schematic diagram of the circuit structure of a first resistor module of a lithium battery protection circuit provided by a certain embodiment of the utility model. Figure 6 As shown, the first resistance module 103 is composed of a plurality of resistors in series, and the first resistance module 103 is used to shunt and limit the discharge capacity of the main circuit. One possible implementation method is: Figure 5 The first resistor module 103 is obtained by connecting resistors R14, R15, R16, R17, R18, R19, R20, R21, R23 and R24 in series. The first resistor module 103 can also be formed by using resistors with the same resistance value as the resistor string.

[0060] As an example of this embodiment, see Figure 7 , Figure 7 This is a schematic diagram of the circuit structure of the second protection module of a lithium battery protection circuit provided by a certain embodiment of the utility model. Figure 6As shown, the second protection switch 108 is composed of a plurality of MOS tubes, and the second protection switch 108 is used to control the on and off of the second protection circuit 107; one implementation method is: the second MOS tube M2, the second diode D4 and the second capacitor C17 constitute the second protection switch 108, the first control end of the second protection switch 108 is connected to the PULS pin of the power metering circuit 1010, the first connection end of the second protection switch 108 is connected to the positive side line 105 through the second resistance module 109, and the second connection end of the second protection switch 108 is grounded.

[0061] The second resistance module 109 is composed of a plurality of resistors, and the second resistance module 109 is used to shunt and limit the discharge capacity of the main circuit 104 and to protect the circuit. Figure 7 R25 and R1 in;

[0062] As another example of this embodiment, see Fig. 9 , Fig. 9 A fourth protection circuit structure diagram of a lithium battery protection circuit provided in a certain embodiment of the utility model; Fig. 9 As shown, the fourth protection circuit is similar in structure to the third protection circuit and has the same function, including:

[0063] The second protection IC is connected in series with the second main circuit protection MOS;

[0064] The second main circuit protection MOS includes several MOS tube groups, and one implementation method is: using U2 as the second protection IC, and using the third MOS tube group Q3 and the fourth MOS tube group Q4 in parallel to obtain the second main circuit protection MOS.

[0065] It is worth mentioning that in a lithium battery protection circuit provided in a certain embodiment of the present utility model, there may be only one third protection circuit 301, or there may be Fig. 9 The fourth protection circuit is shown.

[0066] As another example of this embodiment, in a lithium battery protection circuit provided by the embodiment of the utility model, the main circuit 104 further includes: a third resistance module 1011;

[0067] The third resistance module 1011 is connected to the first resistance module 103, and the connection circuit between the third resistance module 1011 and the first resistance module 103 is used to shunt and limit the discharge capacity of the main circuit;

[0068] The third resistance module 1011 is connected to the power measurement circuit 1010 , and the connection circuit between the third resistance module 1011 and the power measurement circuit 1010 is used to select or activate each protection module.

[0069] The third resistor module 1011 is composed of a number of current-sensing precision resistors; one possible implementation method is as follows: Figure 5 As shown, the third resistor module 1011 is formed by connecting a first precision resistor RS1 and a second precision resistor RS2 in parallel.

[0070] As another example of this embodiment, see Fig.10 , Fig.10 This is a schematic diagram of a power metering circuit structure of a lithium battery protection circuit provided by a certain embodiment of the utility model. Fig.10 As shown, the power metering circuit 1010 further includes: a third protection IC 204;

[0071] The third protection IC 204 includes: a first control pin 208 and a second control pin 2010;

[0072] The first control pin 208 is used to output a high level to control the first protection circuit to be turned on when the power of the main circuit is greater than a preset required range;

[0073] The second control pin 2010 is used to output a high level to control the second protection circuit to be turned on when the power of the main circuit is less than the preset required range.

[0074] In addition, the temperature detection pin 209 of the power metering circuit is connected to the temperature sensor module 2011 , and one implementation is: the temperature detection pin 209 of the third protection IC 204 is connected to the thermistor RT1 of the temperature sensor module 2011 .

[0075] It is worth mentioning that the third resistance module 1011 is connected to the power metering circuit 1010, and the connection circuit between the third resistance module 1011 and the power metering circuit 1010 is used to select or activate each protection module. In this embodiment, one explanation can be: the power metering circuit 1010 controls the MOS to be turned on or off according to the detected electrical signal, and controls the circuit of the third resistance module 1011 to be turned on or off. When the power metering circuit 1010 detects that the battery temperature is too high or the power is too low, it gives a high signal to the MOS, the MOS is turned on, the third resistance module 1011 is turned on, and the battery is protected. When the power metering circuit 1010 detects that the battery temperature is normal and the power is normal, it gives a low signal to the MOS, the MOS is turned off, the third resistance module 1011 is turned off, and the battery can be normally charged and discharged. In addition, when the SRN pin of the power metering circuit 1010 outputs the CS1 signal, it triggers the reset operation of the protection module and is connected to the CS pin of each protection module to select or activate the protection module; when the circuit needs to be reset, the protection module can be ensured to be in the correct working state to protect the battery from dangerous situations such as overcharging, overdischarging, and short circuit, thereby improving the reliability and safety of the battery protection circuit.

[0076] As another example of this embodiment, the lithium battery protection circuit further includes:

[0077] A plurality of capacitors and a plurality of resistors; the plurality of capacitors and the plurality of resistors are used to protect the circuit.

[0078] The utility model also provides a lithium battery having the lithium battery protection circuit arranged therein.

[0079] The utility model adds a first protection circuit and a second protection circuit, and detects the battery cell power and temperature according to the power metering circuit. Under high temperature and high power conditions, the discharge circuit composed of the first protection switch and the first resistor module is shunted, and the current of the main circuit is limited to discharge with a smaller current, and cannot discharge with a large current; under low power conditions, the discharge circuit composed of the second protection switch and the second resistor module forms a discharge barrier to prevent excessive discharge of the battery under low power conditions, thereby protecting the battery, and the current of the main circuit is affected to a certain extent and cannot discharge with a larger current under low power conditions. Through the protection of the first protection circuit and the second protection circuit, the battery is effectively prevented from being overcharged during charging and discharging, and the damage to the battery cell caused by excessive current or too low power is reduced, thereby improving the battery life.

[0080] Example 2

[0081] This embodiment adopts Figure 1 The module structure diagram of a lithium battery protection circuit shown is used to explain the circuit principle.

[0082] When the first protection circuit 101 is working, since the first protection circuit 101 loop and the main loop 104 are in parallel and the first protection circuit 101 loop resistance is relatively large, the first protection circuit 101 divides part of the current, and the current of the main loop 104 is limited to discharge a smaller current, but cannot discharge a large current.

[0083] When the second protection circuit 107 is working, since the second protection circuit 107 and the main circuit 104 are in parallel and the resistance of the second protection circuit 107 is very large, the overall resistance after parallel connection is relatively large, which has a more obvious effect on hindering the discharge of the battery, preventing the battery from over-discharging in a low-power state and thus protecting the battery. The current of the main circuit 104 is affected to a certain extent and cannot discharge with a large current in a low-power state.

[0084] As another example of this embodiment, the third protection IC204 of the power metering circuit 1010 detects the battery cell power and battery temperature through the BAT pin (third pin 207) and the TS pin (temperature detection pin 209). When the temperature and power exceed the set value, the INT pin (first control pin 208) of the third protection IC204 outputs a high level to control the first protection switch 102 to be turned on. The discharge circuit composed of the first protection switch 102, the first resistor module 103 and the third resistor module 1011 is turned on to reduce the battery power, which can protect the battery and extend the battery life under high temperature and high power conditions (battery cell factory data shows that under high temperature and high power conditions, the battery cell self-discharges more violently and the life will be reduced to a certain extent. Therefore, reducing the battery cell power under high temperature conditions can extend the battery cell life and thus extend the battery life). When the third protection IC204 of the power metering circuit 1010 detects that the power of the battery cell is lower than the set value through the BAT pin (the third pin 207), the PULS pin (the second control pin 2010) of the third protection IC204 outputs a high level to control the second protection circuit 107 to be turned on. The discharge loop composed of the second protection circuit 107 and the second resistance module 109 is turned on to prevent the battery from carrying a load when the battery is low in power, thereby protecting the battery and extending the battery life when the battery is low in power.

[0085] The utility model realizes the protection of lithium-ion batteries under conditions of high temperature, high power and low power, prolongs the life of lithium-ion batteries, reduces the replacement cycle of batteries at the whole machine end, and makes certain contributions to saving lithium ore and protecting the natural environment.

[0086] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the protection scope of the present invention.

[0087] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are contradictory.

[0088] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

Claims

1. A lithium battery protection circuit, characterized in that: include: A main circuit, a first protection circuit, a second protection circuit and an electric quantity measurement circuit; wherein the main circuit comprises a positive side circuit and a negative side circuit for connecting the positive and negative ends of the battery cell; The first protection circuit includes: a first protection switch and a first resistance module; the first control end of the first protection switch is connected to the power metering circuit, the first connection end of the first protection switch is connected to the negative electrode side line, and the second connection end of the first protection switch is connected to the first resistance module; The second protection circuit includes: a second protection switch and a second resistance module; the first control end of the second protection switch is connected to the power metering circuit, the first connection end of the second protection switch is connected to the positive side line through the second resistance module, and the second connection end of the second protection switch is grounded; The power metering circuit is used to detect the power and temperature of the battery cell, wherein the first pin, the second pin and the third pin of the power metering circuit are respectively connected to the positive side circuit, and the temperature detection pin of the power metering circuit is connected to the temperature sensor module.

2. A lithium battery protection circuit as claimed in claim 1, characterized in that: Also included: a third protection circuit; The third protection circuit comprises: a first protection IC and a first main loop protection MOS; The first protection IC and the first main circuit protection MOS are connected in series; One end of the first protection IC is connected to the positive side line of the main circuit through the second resistor module, and the first protection IC is used to monitor the battery status, overcharge and overdischarge protection, and overcurrent protection; The first main circuit protection MOS includes a plurality of MOS tube groups, and the first main circuit protection MOS is used for battery reverse protection.

3. A lithium battery protection circuit as claimed in claim 1, characterized in that: The first protection switch is composed of a plurality of MOS tubes, and is used to control the on and off of the first protection circuit.

4. A lithium battery protection circuit as claimed in claim 1, characterized in that: The first resistance module is composed of a plurality of resistors connected in series, and is used for shunting and limiting the discharge capacity of the main circuit.

5. A lithium battery protection circuit as claimed in claim 1, characterized in that: The second protection switch is composed of a plurality of MOS tubes, and is used to control the on and off of the second protection circuit.

6. A lithium battery protection circuit as claimed in claim 1, characterized in that: The second resistance module is composed of a plurality of resistors, and is used for shunting and limiting the discharge capacity of the main circuit and protecting the circuit.

7. A lithium battery protection circuit as claimed in claim 1, characterized in that: The main circuit further includes: a third resistance module; The third resistor module is connected to the first resistor module, and the connection circuit between the third resistor module and the first resistor module is used to shunt and limit the discharge capacity of the main circuit; The third resistance module is connected to the power metering circuit, and the connection circuit between the third resistance module and the power metering circuit is used to select or activate each protection module; specifically, the power metering circuit is used to control the conduction or shutdown of the third resistance module to protect the battery.

8. A lithium battery protection circuit as claimed in claim 7, characterized in that: The third resistor module is composed of a plurality of current-sensing precision resistors.

9. A lithium battery protection circuit as claimed in claim 1, characterized in that: The power metering circuit further includes: a third protection IC; The third protection IC includes: a first control pin and a second control pin; The first control pin is used to output a high level to control the first protection circuit to be turned on when the power of the main circuit is greater than a preset required range; The second control pin is used to output a high level to control the second protection circuit to be turned on when the power of the main circuit is less than the preset requirement range.

10. A lithium battery, characterized in that: A lithium battery protection circuit as described in any one of claims 1 to 9 is arranged inside.

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