Protection plate capable of randomly allocating lithium battery protection current

Abstract

The utility model relates to the technical field of lithium batteries, and discloses a lithium battery protection board capable of randomly allocating protection current, which comprises a protection chip, a first current detection circuit, a second current detection circuit, a first protection switch circuit and a second protection switch circuit, and is characterized in that the lithium battery is respectively and electrically connected with the protection chip and the first current detection circuit; the first current detection circuit is connected with the first protection switch circuit, and the first protection switch circuit is connected with the protection chip to form a first loop; the protection board has the advantages that the overcurrent protection value of one loop is adjusted, the other loop is not changed, the overcurrent protection value of the charging and discharging loop can be independently adjusted by changing the resistance value of the current detection resistor, compared with replacement of a protection chip, the current detection resistor replacement cost is low, operation is convenient, and the current detection resistor replacement cost is low due to the fact that the resistance value of the current detection resistor has multiple choices. Therefore, the charging and discharging loop can more flexibly deploy the overcurrent protection value; the problem that any overcurrent protection value cannot be flexibly adjusted by a protection plate with a charging and discharging split port design is solved.

Description

Technical Field

[0001] The utility model relates to the technical field of lithium batteries, in particular to a protection plate of a lithium battery whose protection current can be arbitrarily adjusted. Background Art

[0002] As a manufacturer of lithium-ion battery packs, the design based on the protection board should be the core competitiveness of the product, so the R&D focus should be on the research, development and testing of the protection board design.

[0003] At present, there are two common solutions for the design of charging and discharging ports of protection boards:

[0004] Solution 1: The charging overcurrent protection voltage and the discharging overcurrent protection voltage of the protection chip are consistent and there is only one current sensing resistor. With this design, the overcurrent protection can only select the largest overcurrent protection value from the charging overcurrent protection value and the discharging overcurrent protection value as the overcurrent protection value for charging and discharging. However, this design will cause one of the protection overcurrent values ​​to be too large, resulting in excess performance or safety risks, and at the same time, the protection function in the product will be mistakenly considered to be invalid. Replacing the protection chip can also adjust the overcurrent protection value, but replacing the protection chip requires selecting the protection chip, which is time-consuming, complicated, and costly, and there is a situation where a suitable protection chip cannot be found.

[0005] Solution 2: The charging overcurrent protection voltage and the discharging overcurrent protection voltage of the protection chip are inconsistent and there is only one current sensing resistor. With this solution design, there is no need to select the largest overcurrent protection value from the charging overcurrent protection value and the discharging overcurrent protection value as the overcurrent protection value for charging and discharging. By selecting a protection chip that meets the requirements for the charging overcurrent protection value and the discharging overcurrent protection value, the charging circuit can take protective action when the required overcurrent protection value is reached and the discharging circuit can take protective action when the required overcurrent protection value is reached. When any overcurrent protection value needs to be adjusted, the overcurrent protection value can be adjusted by changing the resistance of the current sensing resistor, but it often causes another overcurrent protection value to not meet the requirements, or causes excess performance or safety risks. Similarly, the overcurrent protection value can also be adjusted by replacing the protection chip, but replacing the protection chip requires the selection of the protection chip, which is time-consuming and complicated, with high cost, and there is almost no protection chip that meets the large difference between the charging overcurrent protection value and the discharging overcurrent protection value. Utility Model Content

[0006] The utility model aims to provide a protection board with arbitrarily adjustable protection current for lithium batteries, aiming to solve the problem in the prior art that the protection board with separate charge and discharge ports cannot flexibly adjust any overcurrent protection value.

[0007] The utility model is implemented as follows: a protection board with arbitrarily adjustable lithium battery protection current comprises a protection chip, a first current detection circuit, a second current detection circuit, a first protection switch circuit and a second protection switch circuit, wherein the lithium battery protection chip is electrically connected to the first current detection circuit, the first current detection circuit is connected to the first protection switch circuit, and the first protection switch circuit is connected to the protection chip to form a first loop;

[0008] The lithium battery is electrically connected to the second current detection circuit, the second current detection circuit is connected to the second protection switch circuit, and the second protection switch circuit is connected to the protection chip to form a second loop.

[0009] Furthermore, the first current detection circuit includes a first current detection resistor and a second current detection resistor, and the protection chip is connected to the first current detection resistor and the second current detection resistor to perform current detection of the first loop;

[0010] The second current detection circuit includes the second current detection resistor, and the protection chip is connected to the second current detection resistor to perform current detection of the second loop.

[0011] Furthermore, the first protection switch circuit includes a first protection switch; and the second protection switch circuit includes a second protection switch.

[0012] Furthermore, the lithium battery is connected to the protection chip and the second current-sensing resistor respectively, the second current-sensing resistor is connected to the first current-sensing resistor, the first current-sensing resistor is connected to the first protection switch, and the first protection switch is connected to the protection chip to form the first loop;

[0013] The lithium battery is connected to the protection chip and the second current-sensing resistor respectively, the second current-sensing resistor is connected to the second protection switch, and the second protection switch is connected to the protection chip to form the second loop.

[0014] Furthermore, one end of the second current-sensing resistor is connected to the negative end of the lithium battery and the ground terminal of the protection chip, the other end of the second current-sensing resistor is connected to one end of the first current-sensing resistor, the other end of the first current-sensing resistor is connected to the overcurrent detection terminal of the protection chip and one end of the first protection switch, the control end of the first protection switch is connected to the first control switch terminal of the protection chip, and the other end of the first protection switch is connected to the negative pole of the first circuit.

[0015] Furthermore, one end of the second current sensing resistor is connected to the negative end of the lithium battery and the ground terminal of the protection chip, the other end of the second current sensing resistor is connected to one end of the second protection switch, the control end of the second protection switch is connected to the second control switch terminal of the protection chip, and the other end of the second protection switch is connected to the negative pole of the second circuit.

[0016] Further, when the first protection switch is used as a discharge MOS, the second protection switch is used as a charge MOS, the first loop is used as a discharge loop, and the second loop is used as a charge loop;

[0017] The positive electrode of the lithium battery is connected to the first pin of the protection chip and to the positive electrode of the charging port and the positive electrode of the discharging port at the same time, the negative electrode of the lithium battery is connected to the left pin of the second current-sensing resistor, the right pin of the second current-sensing resistor is connected to the left pin of the first current-sensing resistor, the right pin of the first current-sensing resistor is connected to the source (S) pin of the discharging MOS, the eighth pin of the protection chip is connected to the gate (G) of the discharging MOS, and the drain (D) pin of the discharging MOS is connected to the negative electrode of the discharging port, forming the discharging circuit;

[0018] The right pin of the second current sensing resistor is connected to the source (S) pin of the charging MOS, the 9th pin of the protection chip is connected to the gate (G) of the charging MOS, and the drain (D) pin of the charging MOS is connected to the negative pole of the charging port to form the charging circuit.

[0019] Furthermore, the seventh pin of the protection chip is an overcurrent detection terminal, and the seventh pin of the protection chip is simultaneously connected to the right pin of the first current sensing resistor and the source (S) pin of the discharge MOS.

[0020] Furthermore, the 8th pin of the protection chip is the control terminal of the discharge MOS, and the 8th pin of the protection chip is connected to the gate (G) pin of the discharge MOS to control the on and off of the discharge MOS. The 8th pin of the protection chip outputs a high level by default, and the gate (G) pin of the discharge MOS is a high level, and the discharge MOS is turned on.

[0021] Furthermore, the 9th pin of the protection chip is the control terminal of the charging MOS, and the 9th pin of the protection chip is connected to the gate (G) pin of the charging MOS to control the on and off of the charging MOS. The 9th pin of the protection chip outputs a high level by default, and the gate (G) pin of the charging MOS is a high level, and the charging MOS is turned on.

[0022] Compared with the prior art, the utility model provides a protection board with arbitrarily adjustable lithium battery protection current. The protection board has the advantage that the overcurrent protection value of one circuit can be adjusted without changing the other circuit, and the overcurrent protection value of the charge and discharge circuit can be independently adjusted by changing the resistance value of the current sensing resistor. Compared with replacing the protection chip, replacing the current sensing resistor is low in cost and easy to operate. Since the resistance value of the current sensing resistor can be selected in many ways, the overcurrent protection value of the charge and discharge circuit can be more flexibly adjusted. The problem that the protection board with separate charge and discharge ports cannot flexibly adjust any overcurrent protection value is solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a framework diagram of a protection board with arbitrarily adjustable protection current for lithium batteries provided by the utility model;

[0024] Figure 2 The utility model provides a circuit diagram in which the charging overcurrent protection value is higher than the discharging current protection value;

[0025] Figure 3 The utility model provides a circuit diagram in which the discharge overcurrent protection value is higher than the charging current protection value.

[0026] In the figure: lithium battery 10, protection chip 20, first current detection circuit 30, second current detection circuit 40, first protection switch circuit 50, second protection switch circuit 60, first loop 70, second loop 80, first current detection resistor 31, second current detection resistor 41, first protection switch 51, second protection switch 61. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solution and advantages of the utility model more clear, the utility model is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the utility model and are not used to limit the utility model.

[0028] The implementation of the present utility model is described in detail below in conjunction with specific embodiments.

[0029] The same or similar numbers in the drawings of this embodiment correspond to the same or similar parts; in the description of the present utility model, it should be understood that if the terms "upper", "lower", "left", "right" and the like indicate directions or positional relationships based on the directions or positional relationships shown in the drawings, it is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes and cannot be understood as a limitation on the present utility model. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0030] Reference Figure 1-3 As shown, it is a preferred embodiment provided by the utility model.

[0031] A protection board with an adjustable protection current for a lithium battery 10 includes a protection chip 20, a first current detection circuit 30, a second current detection circuit 40, a first protection switch 51 circuit 50, and a second protection switch 61 circuit 60. The protection chip 20 and the first current detection circuit 30 are electrically connected to the lithium battery 10, the first current detection circuit 30 is connected to the first protection switch 51 circuit 50, and the first protection switch 51 circuit 50 is connected to the protection chip 20 to form a first loop 70.

[0032] The lithium battery 10 is electrically connected to the second current detection circuit 40 , the second current detection circuit 40 is connected to the second protection switch 61 circuit 60 , and the second protection switch 61 circuit 60 is connected to the protection chip 20 to form a second loop 80 .

[0033] The protection board provided above can arbitrarily adjust the protection current of the lithium battery 10. The protection board has the advantage that the overcurrent protection value of one circuit can be adjusted without changing the other circuit, and the overcurrent protection value of the charging and discharging circuit can be independently adjusted by changing the resistance value of the current sensing resistor. Compared with replacing the protection chip 20, replacing the current sensing resistor is low-cost and easy to operate. Since the resistance value of the current sensing resistor can be selected in many ways, the overcurrent protection value of the charging and discharging circuit can be more flexibly adjusted; the problem that the protection board with separate charging and discharging ports cannot flexibly adjust any overcurrent protection value is solved.

[0034] In this embodiment, the first current detection circuit 30 includes a first current detection resistor 31 and a second current detection resistor 41, and the protection chip 20 is connected to the first current detection resistor 31 and the second current detection resistor 41 to perform current detection of the first loop 70;

[0035] The second current detection circuit 40 includes a second current detection resistor 41 , and the protection chip 20 is connected to the second current detection resistor 41 to detect the current of the second loop 80 .

[0036] The first protection switch 51 circuit 50 includes a first protection switch 51 ; the second protection switch 61 circuit 60 includes a second protection switch 61 .

[0037] The lithium battery 10 is connected to the protection chip 20 and the second current sensing resistor 41 respectively, the second current sensing resistor 41 is connected to the first current sensing resistor 31, the first current sensing resistor 31 is connected to the first protection switch 51, and the first protection switch 51 is connected to the protection chip 20 to form a first loop 70;

[0038] The lithium battery 10 is connected to the protection chip 20 and the second current-detecting resistor 41 , respectively. The second current-detecting resistor 41 is connected to the second protection switch 61 . The second protection switch 61 is connected to the protection chip 20 , forming a second loop 80 .

[0039] One end of the second current sensing resistor 41 is connected to the negative end of the lithium battery 10 and the ground terminal of the protection chip 20, the other end of the second current sensing resistor 41 is connected to one end of the first current sensing resistor 31, the other end of the first current sensing resistor 31 is connected to the overcurrent detection terminal of the protection chip 20 and one end of the first protection switch 51, the control end of the first protection switch 51 is connected to the first control switch terminal of the protection chip 20, and the other end of the first protection switch 51 is connected to the negative pole of the first loop 70.

[0040] One end of the second current sensing resistor 41 is connected to the negative end of the lithium battery 10 and the ground terminal of the protection chip 20, the other end of the second current sensing resistor 41 is connected to one end of the second protection switch 61, the control end of the second protection switch 61 is connected to the second control switch terminal of the protection chip 20, and the other end of the second protection switch 61 is connected to the negative pole of the second loop 80.

[0041] Specific circuit diagram: Figure 2 As shown, the charging overcurrent protection value of this design is 16.7A, and the discharging overcurrent protection value is 3.3A. The charging overcurrent protection value is higher than the discharging overcurrent protection value, so the actual circuit diagram is as shown in the figure of the specification. Figure 2 shown.

[0042] The protection chip 20 is implemented by a protection chip 20 of model CM1022, which has a built-in high-precision voltage detection circuit and a current detection circuit; the CM1022 protection chip 20 is named U1 in this circuit, and the charging overcurrent protection voltage value and the discharging overcurrent protection voltage value in the overcurrent detection function of U1 are the same and are fixed values, and the overcurrent detection terminal of U1 is the 7th pin; the second current sensing resistor 41 is a current sensing resistor with a resistance value of 6mΩ, named R2; the first current sensing resistor 31 is a current sensing resistor with a resistance value of 25mΩ, named R1.

[0043] In the drawings in the specification Figure 2 In the design shown, the discharge overcurrent protection value is lower than the charge overcurrent protection value. Since there are two current-sensing resistors connected in series on the first loop 70, the resistance value is large, and the current passing through the first loop 70 is small, so the first loop 70 is suitable for a loop with a small overcurrent protection value; there is only one second current-sensing resistor 41 on the second loop 80, so the current passing through the second loop 80 is large, and the second loop 80 is suitable for a loop with a large overcurrent protection value; therefore, the first protection switch 51 is used as a discharge MOS, the second protection switch 61 is used as a charging MOS, the first loop 70 is used as a discharge loop, and the second loop 80 is used as a charging loop; wherein, R3 is a resistor in the recommended circuit design of the CM1022 chip, which plays a current limiting protection function, and F1 is a fuse for the entire loop. R3 and F1 are not the focus of this design, so they are not described in detail below.

[0044] In this embodiment, when the first protection switch 51 is used as a discharge MOS, the second protection switch 61 is used as a charge MOS, the first loop 70 is used as a discharge loop, and the second loop 80 is used as a charge loop;

[0045] The positive electrode of the lithium battery 10 is simultaneously connected to the first pin of the protection chip 20 and to the positive electrode of the charging port and the positive electrode of the discharging port. The negative electrode of the lithium battery 10 is connected to the left pin of the second current sensing resistor 41, the right pin of the second current sensing resistor 41 is connected to the left pin of the first current sensing resistor 31, the right pin of the first current sensing resistor 31 is connected to the source (S) pin of the discharging MOS, the eighth pin of the protection chip 20 is connected to the gate (G) of the discharging MOS, and the drain (D) pin of the discharging MOS is connected to the negative electrode of the discharging port, forming a discharging circuit.

[0046] The right pin of the second current detection resistor 41 is connected to the source (S) pin of the charging MOS, the 9th pin of the protection chip 20 is connected to the gate (G) of the charging MOS, and the drain (D) pin of the charging MOS is connected to the negative pole of the charging port to form a charging circuit.

[0047] The 7th pin of the protection chip 20 is an overcurrent detection terminal, and the 7th pin of the protection chip 20 is connected to the right pin of the first current detection resistor 31 and the source (S) pin of the discharge MOS at the same time.

[0048] The 8th pin of the protection chip 20 is the control terminal of the discharge MOS. The 8th pin of the protection chip 20 is connected to the gate (G) pin of the discharge MOS to control the on and off of the discharge MOS. The 8th pin of the protection chip 20 outputs a high level by default. The gate (G) pin of the discharge MOS is at a high level and the discharge MOS is turned on.

[0049] The 9th pin of the protection chip 20 is the control terminal of the charging MOS. The 9th pin of the protection chip 20 is connected to the gate (G) pin of the charging MOS to control the on and off of the charging MOS. The 9th pin of the protection chip 20 outputs a high level by default. The gate (G) pin of the charging MOS is a high level and the charging MOS is turned on.

[0050] Based on the drawings in the specification Figure 2 The design shown in the figure, the connection of this circuit is as follows:

[0051] 1) The positive electrode of the lithium battery 10 is simultaneously connected to the first pin of the chip U1 and the positive electrode of the charging port and the positive electrode of the discharging port. The negative electrode of the lithium battery 10 is connected to the left pin of the current-sensing resistor R2, the right pin of the current-sensing resistor R2 is connected to the left pin of the current-sensing resistor R1, the right pin of the current-sensing resistor R1 is connected to the source (S) pin of the discharging MOS, the eighth pin of U1 is connected to the gate (G) of the discharging MOS, and the drain (D) pin of the discharging MOS is connected to the negative electrode of the discharging port, forming a discharging circuit; the right pin of the current-sensing resistor R2 is connected to the source (S) pin of the charging MOS, the ninth pin of U1 is connected to the gate (G) of the charging MOS, and the drain (D) pin of the charging MOS is connected to the negative electrode of the charging port, forming a charging circuit;

[0052] 2) The 7th pin of U1 is the overcurrent detection terminal, which is connected to the right pin of R1 and the source (S) pin of the discharge MOS at the same time. The charging overcurrent protection voltage is -0.100V, and the discharging overcurrent protection voltage is 0.100V. The voltage values ​​are the same, and the signs are different for the current flow directions. The 8th pin of U1 is the discharge MOS control terminal, which is connected to the gate (G) pin of the discharge MOS to control the on and off of the discharge MOS. The pin outputs a high level by default. When the gate (G) pin of the discharge MOS is high, the discharge MOS is turned on. The 9th pin of U1 is the charging MOS control terminal, which is connected to the gate (G) pin of the charging MOS to control the on and off of the charging MOS. The pin outputs a high level by default. When the gate (G) pin of the charging MOS is high, the charging MOS is turned on.

[0053] Based on the drawings in the specification Figure 2 The design scheme shown in the figure, the design principle of this circuit is as follows:

[0054] 1) When in the discharge condition, the current flows out from the positive electrode of the lithium battery 10, flows through the load through the positive electrode of the discharge port, flows out from the negative electrode of the load, flows through the discharge MOS drain (D) pin through the negative electrode of the discharge port, and then flows from the discharge MOS source (S) pin through the current sensing resistor R1 and the current sensing resistor R2, and finally returns to the negative electrode of the lithium battery 10;

[0055] When the current flows through the current-sensing resistors R1 and R2, the overcurrent protection of U1 detects the voltage of the current-sensing resistors R1 and R2 in series. When the voltage value exceeds the discharge overcurrent protection voltage value of U1, U1 controls the switch function to output a low level, and the gate (G) pin of the discharge MOS is low, and the discharge MOS is turned off; the resistance value of R1 is 25mΩ, and the resistance value of R2 is 6mΩ. After the series connection, the resistance value of R1 and R2 is 31mΩ, and the discharge overcurrent protection voltage is 0.100V. Therefore, when the current flowing through R1 and R2 is greater than or equal to 100mV / 31mΩ=3.226A, the overcurrent detection terminal of U1 detects that the voltage of the current-sensing resistors R1 and R2 is higher than the overcurrent protection voltage value of U1. At this time, the discharge MOS control terminal of U1 outputs a low level, and controls the discharge MOS to be disconnected, thereby realizing the discharge overcurrent protection function.

[0056] 2) When in charging condition, the current flows from the external charger to the positive electrode of the charging port, and then flows from the positive electrode of the charging port to the positive electrode of the lithium battery 10, and then flows from the negative electrode of the lithium battery 10 to the current sensing resistor R1, and then flows to the drain (D) pin of the charging MOS through the current sensing resistor R1, and then flows from the source (S) pin of the charging MOS to the negative electrode of the charging port, and finally returns to the negative electrode of the external charger; when the current flows from the negative electrode of the lithium battery 10 and passes through the current sensing resistor R1, there is a voltage on the current sensing resistor R1. When the voltage exceeds the charging overcurrent protection voltage of U1, U1 controls the switch function output After the low level is output, the gate (G) pin of the charging MOS is at a low level, and the charging MOS is turned off; the resistance of R2 is 6mΩ, and the charging overcurrent protection voltage is -0.100V, so when the current flowing through the current sensing resistor R1 is greater than or equal to -100mV / 6mΩ=-16.6A (the symbol only indicates that the charging current is in opposite directions to the discharging current), the overcurrent detection terminal of U1 detects that the voltage of the current sensing resistor R2 is higher than the overcurrent protection voltage value of U1. At this time, the charging MOS control terminal of U1 outputs a low level, controlling the charging MOS to disconnect, thereby realizing the charging overcurrent protection function.

[0057] Based on the drawings in the specification Figure 3 The figure shows the circuit design scheme when the discharge overcurrent protection value in the project technical requirements is higher than the charging current protection value; the required technical requirements can be met by simply using the first circuit 70 as a discharge circuit and the second circuit 80 as a charging circuit; when the customer needs to modify the overcurrent protection value of the project, the charging overcurrent protection value and the discharge overcurrent protection value of the protection board can be changed quickly and efficiently by simply changing the resistance value of the current sensing resistor.

[0058] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A protection board with an adjustable lithium battery protection current, characterized in that: It includes a protection chip, a first current detection circuit, a second current detection circuit, a first protection switch circuit and a second protection switch circuit, wherein the lithium battery protection chip and the first current detection circuit are electrically connected, the first current detection circuit is connected to the first protection switch circuit, and the first protection switch circuit is connected to the protection chip to form a first loop; The lithium battery is electrically connected to the second current detection circuit, the second current detection circuit is connected to the second protection switch circuit, and the second protection switch circuit is connected to the protection chip to form a second loop.

2. The protection board with adjustable protection current for lithium battery as claimed in claim 1, characterized in that: The first current detection circuit includes a first current detection resistor and a second current detection resistor, and the protection chip is connected to the first current detection resistor and the second current detection resistor to perform current detection of the first loop; The second current detection circuit includes the second current detection resistor, and the protection chip is connected to the second current detection resistor to perform current detection of the second loop.

3. The protection board with adjustable protection current for lithium battery as claimed in claim 2, characterized in that: The first protection switch circuit includes a first protection switch; the second protection switch circuit includes a second protection switch.

4. The protection board with arbitrarily adjustable protection current for lithium batteries as claimed in claim 3, characterized in that: The lithium battery is connected to the protection chip and the second current-sensing resistor respectively, the second current-sensing resistor is connected to the first current-sensing resistor, the first current-sensing resistor is connected to the first protection switch, and the first protection switch is connected to the protection chip to form the first loop; The lithium battery is connected to the protection chip and the second current-sensing resistor respectively, the second current-sensing resistor is connected to the second protection switch, and the second protection switch is connected to the protection chip to form the second loop.

5. The protection board with adjustable protection current for lithium battery as claimed in claim 4, characterized in that: One end of the second current sensing resistor is connected to the negative end of the lithium battery and the ground terminal of the protection chip, the other end of the second current sensing resistor is connected to one end of the first current sensing resistor, the other end of the first current sensing resistor is connected to the overcurrent detection terminal of the protection chip and one end of the first protection switch, the control end of the first protection switch is connected to the first control switch terminal of the protection chip, and the other end of the first protection switch is connected to the negative pole of the first circuit.

6. The protection board with adjustable protection current for lithium battery as claimed in claim 4, characterized in that: One end of the second current sensing resistor is connected to the negative end of the lithium battery and the ground terminal of the protection chip, the other end of the second current sensing resistor is connected to one end of the second protection switch, the control end of the second protection switch is connected to the second control switch terminal of the protection chip, and the other end of the second protection switch is connected to the negative pole of the second circuit.

7. The protection board with arbitrarily adjustable protection current for lithium batteries as claimed in any one of claims 3 to 6, characterized in that: When the first protection switch is used as a discharge MOS, the second protection switch is used as a charge MOS, the first loop is used as a discharge loop, and the second loop is used as a charge loop; The positive electrode of the lithium battery is connected to the first pin of the protection chip and to the positive electrode of the charging port and the positive electrode of the discharging port at the same time, the negative electrode of the lithium battery is connected to the left pin of the second current-sensing resistor, the right pin of the second current-sensing resistor is connected to the left pin of the first current-sensing resistor, the right pin of the first current-sensing resistor is connected to the source (S) pin of the discharging MOS, the eighth pin of the protection chip is connected to the gate (G) of the discharging MOS, and the drain (D) pin of the discharging MOS is connected to the negative electrode of the discharging port, forming the discharging circuit; The right pin of the second current sensing resistor is connected to the source (S) pin of the charging MOS, the 9th pin of the protection chip is connected to the gate (G) of the charging MOS, and the drain (D) pin of the charging MOS is connected to the negative pole of the charging port to form the charging circuit.

8. The protection board with adjustable protection current for lithium battery as claimed in claim 7, characterized in that: The seventh pin of the protection chip is an overcurrent detection terminal, and the seventh pin of the protection chip is connected to the right pin of the first current detection resistor and the source (S) pin of the discharge MOS at the same time.

9. The protection board with adjustable protection current for lithium battery as claimed in claim 8, characterized in that: The 8th pin of the protection chip is the control terminal of the discharge MOS. The 8th pin of the protection chip is connected to the gate (G) pin of the discharge MOS to control the on and off of the discharge MOS. The 8th pin of the protection chip outputs a high level by default. When the gate (G) pin of the discharge MOS is at a high level, the discharge MOS is turned on.

10. The protection board with adjustable protection current for lithium battery as claimed in claim 9, characterized in that: The 9th pin of the protection chip is the control terminal of the charging MOS. The 9th pin of the protection chip is connected to the gate (G) pin of the charging MOS to control the on and off of the charging MOS. The 9th pin of the protection chip outputs a high level by default. When the gate (G) pin of the charging MOS is at a high level, the charging MOS is turned on.

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