Protection circuit of battery pack charging interface and battery pack

Abstract

The utility model discloses a protection circuit of a charging interface of a battery pack and the battery pack, and the protection circuit of the charging interface of the battery pack comprises a signal receiving module, a positive electrode control module, a control module, a negative electrode control module, a positive electrode charging interface, a negative electrode charging interface and a KEY interface, when the positive electrode charging interface, the negative electrode charging interface and the KEY interface are not connected with the charger, the positive electrode charging interface, the negative electrode charging interface and the KEY interface are suspended, the signal receiving module, the positive electrode control module, the control module and the negative electrode control module are all in a cut-off state, the positive electrode control module blocks the positive electrode of the battery from the positive electrode charging interface, and the negative electrode control module blocks the negative electrode of the battery from the negative electrode charging interface. The negative electrode control module blocks the negative electrode of the battery from the negative electrode charging interface, so that the voltage at the two ends of the battery is isolated from the positive electrode charging interface and the negative electrode charging interface, electric leakage at the positive electrode charging interface and the negative electrode charging interface is prevented, the metal charging interface is prevented from being corroded by electrolytic reaction in water, and the service life of the battery is effectively prolonged.

Description

Technical Field

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

[0002] With the vigorous development of lithium battery technology, lithium batteries have the advantages of high energy density, low self-consumption, wide operating temperature and excellent reliability. They are widely used in 3C, energy storage, electric vehicles, underwater and other fields.

[0003] Among them, lithium battery packs used underwater generally need to expose the metal charging port due to the need for charging, and add a reverse diode to the charging port to prevent the charging port from having voltage, which will cause electrolysis during underwater use, thereby corroding the exposed metal charging port. However, the diode has leakage phenomenon, and when the charging interface contacts electrolytes such as water, the metal charging port will be slowly electrolytically corroded, which will affect the service life of the device. Utility Model Content

[0004] In view of the deficiencies in the prior art, a protection circuit for a battery pack charging interface and a battery pack are provided.

[0005] To achieve the above-mentioned purpose, the utility model provides a protection circuit for a battery pack charging interface, comprising a signal receiving module, a positive control module, a control module, a negative control module, a positive charging interface, a negative charging interface and a KEY interface, the signal receiving module having a first signal receiving end, a second signal receiving end and a third signal receiving end, the positive control module having a first positive control end, a second positive control end and a third positive control end, the control module having a first control end, a second control end and a third control end, the negative control module having a first negative control end, a second negative control end and a third negative control end, the first signal receiving end is connected to the KEY interface, the second signal receiving end is connected to the first positive control end, the third signal receiving end is connected to the first control end, the second positive control end is connected to the positive charging interface, the third positive control end is connected to the positive electrode of the battery, the second control end is connected to a power supply, the third control end is connected to the first negative control end, the second negative control end is connected to the negative charging interface, and the third negative control end is connected to the negative electrode of the battery.

[0006] According to one embodiment of the utility model, the signal receiving module includes a first control module and a second control module, the first control module and the second control module are connected in series, the first control module and the second control module are respectively connected to the KEY interface, the other end of the first control module is connected to the first positive control end, and the other end of the second control module is connected to the first control end.

[0007] According to one embodiment of the utility model, the control module includes a MOS tube Q3, a resistor R7 and a resistor R8, the gate of the MOS tube Q3 is connected to the third signal receiving end through the resistor R7, the source of the MOS tube Q3 is connected to the power supply, the drain of the MOS tube Q3 is connected to the first negative control end, one end of the resistor R8 is connected to the source of the MOS tube Q3, and the other end thereof is respectively connected to the gate of the MOS tube Q3 and the resistor R7.

[0008] According to an embodiment of the present invention, the signal receiving module further includes a Zener diode Z1, the anode of the Zener diode Z1 is respectively connected to the first control module and the second control module, and the cathode of the Zener diode Z1 is connected to the KEY interface.

[0009] According to one embodiment of the present utility model, the positive electrode control module includes a MOS tube Q2, a resistor R1 and a resistor R2, the drain of the MOS tube Q2 is connected to the positive electrode charging interface, the source of the MOS tube Q2 is connected to the positive electrode of the battery, the gate of the MOS tube Q2 is connected to the second signal receiving end through the resistor R2, and the resistor R2 is connected between the gate of the MOS tube Q2 and the source of the MOS tube Q2.

[0010] According to one embodiment of the present utility model, the negative electrode control module includes a MOS tube Q1, a resistor R9 and a resistor R10, the source of the MOS tube Q1 is connected to the negative electrode charging interface, the gate of the MOS tube Q1 is connected to the third control end through the resistor R9, the source of the MOS tube Q1 is connected to the negative electrode of the battery, one end of the resistor R10 and the drain of the MOS tube Q1 are connected to the negative electrode charging interface, and the other end thereof is respectively connected to the gate of the MOS tube Q1 and the resistor R9.

[0011] According to one embodiment of the present utility model, the first control module includes a transistor Q4, a resistor R3 and a resistor R4, the drain of the transistor Q4 is connected to the first positive control terminal, the gate of the transistor Q4 is connected to the KEY interface through the resistor R4 and the second control module, and the gate of the transistor Q4 is connected to the ground through the resistor R3 and the source of the transistor Q4.

[0012] According to one embodiment of the utility model, the second control module includes a transistor Q5, a resistor R5 and a resistor R6, the gate of the transistor Q5 is connected to the KEY interface with the first control module through the resistor R5, the drain of the transistor Q5 is connected to the first control end, and the gate of the transistor Q5 is grounded through the resistor R6 and the source of the transistor Q5.

[0013] The utility model also provides a battery pack, comprising any protection circuit of the above battery pack charging interface.

[0014] The beneficial effect of the utility model lies in that, by setting a signal receiving module, a positive control module, a control module, a negative control module, a positive charging interface, a negative charging interface and a KEY interface, when the positive charging interface, the negative charging interface and the KEY interface are not connected to the charger, the positive charging interface, the negative charging interface and the KEY interface are suspended, the signal receiving module, the positive control module, the control module and the negative control module are all in a cut-off state, the positive control module blocks the positive electrode of the battery from the positive charging interface, and the negative control module blocks the negative electrode of the battery from the negative charging interface, thereby isolating the voltage at both ends of the battery from the positive charging interface and the negative charging interface, preventing leakage at the positive charging interface and the negative charging interface, avoiding the metal charging interface from being corroded by electrolysis reaction in water, and effectively improving the service life of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0016] Figure 1 is a block diagram of a protection circuit of a battery pack charging interface in an embodiment;

[0017] Figure 2 It is a protection circuit diagram of the battery pack charging interface in the embodiment.

[0018] Description of Reference Numerals

[0019] 1-Signal receiving module; 11-First signal receiving terminal; 12-Second signal receiving terminal; 13-Third signal receiving terminal; 14-First control module; 15-Second control module; 2-Positive control module; 21-First positive control terminal; 22-Second positive control terminal; 23-Third positive control terminal; 3-Control module; 31-First control terminal; 32-Second control terminal; 33-Third control terminal; 4-Negative control module; 41-First negative control terminal; 42-Second negative control terminal; 43-Third negative control terminal; 5-Positive charging interface; 6-Negative charging interface; 7-KEY interface. DETAILED DESCRIPTION

[0020] The following will disclose multiple embodiments of the present invention with drawings. For the purpose of clear description, many practical details will be described together in the following description. However, it should be understood that these practical details should not be used to limit the present invention. In other words, in some embodiments of the present invention, these practical details are not necessary. In addition, in order to simplify the drawings, some conventional structures and components will be depicted in a simple schematic manner in the drawings.

[0021] In addition, in the present utility model, the descriptions of "first", "second", etc. are only used for descriptive purposes, and do not specifically refer to the order or sequence, nor are they used to limit the present utility model. They are only used to distinguish components or operations described with the same technical terms, and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in this field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present utility model.

[0022] Please refer to Figure 1 , Figure 1 This is a block diagram of the protection circuit of the battery pack charging interface in this embodiment. This embodiment provides a protection circuit for the battery pack charging interface, which includes a signal receiving module 1, a positive control module 2, a control module 3, a negative control module 4, a positive charging interface 5, a negative charging interface 6 and a KEY interface 7. Among them, the positive charging interface 5, the negative charging interface 6 and the KEY interface 7 are all charging interfaces of the battery, which are used to connect with the charger, the positive control module 2 is connected between the positive electrode of the battery and the positive charging interface 5, the negative control module 4 is connected between the negative electrode of the battery and the negative charging interface 6, one end of the signal receiving module 1 is connected to the KEY interface, and the other end is connected to the positive control module 2 and the control module 3 respectively, one end of the control module 3 is connected to the negative control module 4, and the connection state between the battery and the charging interface is controlled by the signal receiving module 1, the positive control module 2, the control module 3 and the negative control module 4.

[0023] Specifically, the signal receiving module 1 has a first signal receiving terminal 11, a second signal receiving terminal 12 and a third signal receiving terminal 13. The first signal receiving terminal 11 is connected to the KEY interface 7, the second signal receiving terminal 12 is connected to the positive control module 2, and the third signal receiving terminal 13 is connected to the control module 3. The first signal receiving terminal 11 is used to receive the signal of the KEY interface 7 to detect whether the charger is connected. When the first signal receiving terminal 11 receives a high-level signal from the KEY interface 7, that is, when the charger is connected to the positive charging interface 5, the negative charging interface 6 and the KEY interface 7, the signal receiving module 1 is in a conducting state, so that the positive control module 2 is turned on through the second signal receiving terminal 12, and the control module 3 is turned on through the third signal receiving terminal 13.

[0024] The positive control module 2 has a first positive control terminal 21, a second positive control terminal 22 and a third positive control terminal 23. The first positive control terminal 21 is connected to the signal receiving module 1, the second positive control terminal 22 is connected to the positive charging interface 5, and the third positive control terminal 23 is connected to the positive electrode of the battery. The positive control module 2 is controlled by the signal receiving module 1, and the on and off states of the positive control module 2 are controlled by the signal receiving module 1, thereby controlling the connection and disconnection between the positive electrode of the battery and the positive charging interface 5. When the positive charging interface 5, the negative charging interface 6 and the KEY interface 7 are not connected to the charger, the positive control module 2 blocks the conduction between the positive electrode of the battery and the positive charging interface 5 to avoid leakage at the charging interface. When the positive charging interface 5, the negative charging interface 6 and the KEY interface 7 are connected to the charger, the first signal receiving end 11 receives the high-level signal of the KEY interface 7, the signal receiving module 1 is turned on, and the first positive control end 21 receives the turn-on signal of the signal receiving module 1, so that the positive control module 2 is turned on. At this time, the positive electrode of the battery is connected to the positive charging interface 5, so that the current at the positive charging interface 5 flows to the positive electrode of the battery.

[0025] The control module 3 has a first control terminal 31, a second control terminal 32 and a third control terminal 33. The first control terminal 31 is connected to the third signal receiving terminal 13, the second control terminal 32 is connected to the power supply, and the third control terminal 33 is connected to the negative control module 4. The on-off state of the control module 3 is controlled by the signal receiving module 1, and controls the on-off state of the negative control module 4. When the charger is connected to the positive charging interface 5, the negative charging interface 6 and the KEY interface 7, the first signal receiving terminal 11 receives the high-level signal of the KEY interface 7, so that the signal receiving module 1 is turned on. At the same time, the first control terminal 31 receives the turn-on signal of the signal receiving module 1, so that the control module 3 is turned on, and the conduction of the negative control module 4 is controlled through the third control terminal 33.

[0026] The negative electrode control module 4 has a first negative electrode control terminal 41, a second negative electrode control terminal 42 and a third negative electrode control terminal 43. The first negative electrode control terminal 41 is connected to the third control terminal 33, the second negative electrode control terminal 42 is connected to the negative electrode charging interface 6, and the third negative electrode control terminal 43 is connected to the negative electrode of the battery. The negative electrode control module 4 is used to control the conduction between the negative electrode of the battery and the negative electrode charging interface 6, and the negative electrode control module 4 is controlled by the control module 3. When the control module 3 is turned on, the third control terminal 33 sends the conduction signal of the control module 3 to the negative electrode control module 4, and turns on the negative electrode control module 4, so that the negative electrode of the battery is connected to the negative electrode charging interface 6.

[0027] When charging the battery, connect the charger to the positive charging interface 5, the negative charging interface 6 and the KEY interface 7. The KEY interface 7 receives the signal of the charger connection, and the KEY interface 7 is at a high level. At this time, the signal receiving module 1 is turned on, so that the positive control module 2 and the control module 3 are turned on. At the same time, the negative control module 4 is also turned on. When the positive charging interface 5 is connected to the positive electrode of the battery, and the negative charging interface 6 is connected to the negative electrode of the battery, the circuit forms a complete loop, and the charger charges the battery normally.

[0028] When the positive charging interface 5, the negative charging interface 6 and the KEY interface 7 are not connected to the charger, the signal receiving module 1 does not conduct because it does not receive the connection signal of the charger. At the same time, the positive control module 2 is in the cut-off state, and the control module 3 is not conducting, resulting in the negative control module 4 being in the cut-off state. At this time, the voltage between the two ends of the battery and the charging interface is blocked and isolated, preventing the voltage from leaking from the positive charging interface 5 and the negative charging interface 6, and preventing electrolysis from occurring at the positive charging interface 5 and the negative charging interface 6, thereby corroding the charging interface, thereby achieving the protection effect of the charging interface.

[0029] Please refer to Figure 1 Combined with Figure 2 , Figure 2 The protection circuit diagram of the battery pack charging interface. Further, the signal receiving module 1 includes a first control module 14 and a second control module 15, the first control module 14 and the second control module 15 are connected in series with each other, and the first control module 14 and the second control module 15 are respectively connected to the KEY interface 7, that is, the connection node connected in series with the first control module 14 and the second control module 15 is connected to the KEY interface 7, and the signal of the KEY interface 7 is received at the same time. The other end of the first control module 14 is connected to the first positive control terminal 21, and the other end of the second control module 15 is connected to the first control terminal 31. The first control module 14 is used to control the on and off of the positive control module 2, and the second control module 15 is used to control the on and off of the control module.

[0030] In addition, the signal receiving module 1 further includes a voltage stabilizing diode Z1, one end of which is connected to the KEY interface 7, and the other end of which is respectively connected to the first control module 14 and the second control module 15. The voltage stabilizing diode Z1 is used to increase the threshold voltage of the circuit to avoid accidentally touching the KEY interface 7 and prevent the circuit from malfunctioning.

[0031] Furthermore, the first control module 14 includes a transistor Q4, a resistor R3 and a resistor R4, wherein the drain of the transistor Q4 is connected to the first positive control terminal 21, the source of the transistor Q4 is grounded, the gate of the transistor Q4 is connected to the KEY interface 7 through the resistor R4 and the second control module 15, and the resistor R3 is connected between the gate and the source of the transistor Q4. The resistor R3 and the resistor R4 constitute the bias circuit of the transistor Q4 to control the on and off of the transistor Q4. When the positive charging interface 5, the negative charging interface 6 and the KEY interface 7 are connected to the charger, when the KEY interface 7 is at a high level, the transistor Q4 provides a bias current through the resistor R3 and the resistor R4, so that the transistor Q4 is turned on. When the positive charging interface 5, the negative charging interface 6 and the KEY interface 7 are not connected to the charger, the KEY interface 7 is suspended and the transistor Q4 is turned off.

[0032] The second control module 15 includes a transistor Q5, a resistor R5 and a resistor R6. The drain of the transistor Q5 is connected to the second control terminal 32 through the resistor R7. The gate of the transistor Q5 is connected to the ground with the source of the transistor Q5 after passing through the resistor R6. The resistor R5 is connected between the gate of the transistor Q5 and the KEY interface 7. The resistor R5 and the resistor R6 constitute a bias circuit of the transistor Q5, which is used to control the on and off of the transistor Q5. When the charging interface of the battery is connected to the charger, the KEY interface 7 detects the connection signal of the charger. At this time, the KEY interface 7 is at a high level. The resistor R5 and the resistor R6 provide a bias voltage for the transistor Q5, so that the gate of the transistor Q5 is at a high level and the transistor Q5 is turned on.

[0033] The positive control module 2 includes a MOS tube Q2, a resistor R1 and a resistor R2. The source of the MOS tube Q2 is connected to the positive electrode of the battery, the drain of the MOS tube Q2 is connected to the positive electrode charging interface 5, the gate of the MOS tube Q2 is connected to the drain of the triode Q4 through the resistor R2, and the resistor R1 is connected between the source and the gate of the MOS tube. The resistor R2 and the resistor R2 are bias resistors of the MOS tube Q2.

[0034] When the positive charging interface 5, the negative charging interface 6 and the KEY interface 7 are not connected to the charger, the voltage across the battery is higher than the voltage at the charging interface, and the MOS tube Q2 blocks the battery positive electrode from the charging interface, isolating the battery voltage from the charging interface.

[0035] When the positive charging interface 5, the negative charging interface 6 and the KEY interface 7 are connected to the charger, the KEY interface 7 is at a high level, and the current flows through the resistors R3 and R4, so that the transistor Q4 is turned on. At this time, the resistors R2 and R1 provide a bias voltage for the MOS tube Q3, so that the MOS tube Q2 is turned on. At this time, the voltage at the positive charging interface 5 is higher than the voltage of the positive electrode of the battery, so that the current at the charging interface charges the positive electrode of the battery through the MOS tube Q2.

[0036] The control module 3 includes a MOS tube Q3, a resistor R8 and a resistor R7. The drain of the MOS tube Q3 is connected to the power supply, the source of the MOS tube Q3 is connected to the first negative control terminal 41, the gate of the MOS tube Q3 is connected to the third signal receiving terminal 13 through the resistor R7, and the resistor R8 is connected between the gate and the source of the MOS tube. The resistors R7 and R8 are bias resistors of the MOS tube.

[0037] When the transistor Q5 is in the on state, the resistor R7 and the resistor R8 provide a bias voltage for the MOS transistor Q3, so that the gate of the MOS transistor Q3 is at a high level, and the MOS transistor Q3 is turned on.

[0038] In addition, the control module 3 further includes a diode D1 , one end of the diode D1 is connected to the drain of the MOS tube Q3 , and the other end of the diode D1 is connected to the first cathode control terminal 41 .

[0039] In this embodiment, the anode of the diode D1 is connected to the drain of the MOS transistor Q3, and the cathode of the diode D1 is connected to the first cathode control terminal 41. Since the diode D1 is unidirectional, the battery voltage cannot be output in reverse.

[0040] The negative electrode control module 4 includes a MOS tube Q1, a resistor R9 and a resistor R10. The gate of the MOS tube Q1 is connected to the third control terminal 33 through the resistor R9, the drain of the MOS tube Q1 is connected to the negative electrode of the battery, the source of the MOS tube Q1 is connected to the negative electrode charging interface 6, and the resistor R10 is connected between the gate and the source of the MOS tube.

[0041] When the MOS transistor Q3 is turned on, the resistor R9 and the resistor R10 provide a bias voltage for the MOS transistor Q1 to turn on the MOS transistor Q1 , thereby connecting the negative electrode of the battery to the negative electrode charging interface 6 .

[0042] In summary, when the charger is connected to the positive charging interface 5, the negative charging interface 6 and the KEY interface 7, the KEY interface 7 is at a high level, so that the signal receiving module 1 is turned on, and then the positive control module 2 and the control module 3 are turned on. After the control module 3 is turned on, the negative control module 4 is turned on. As a result, the positive electrode of the battery is turned on to the positive charging interface 5, and the negative electrode of the battery is turned on to the negative charging interface 6, so that the circuit forms a complete loop and the battery is charged normally.

[0043] When the positive charging interface 5, the negative charging interface 6 and the KEY interface 7 are not connected to the charger, the positive charging interface 5, the negative charging interface 6 and the KEY interface 7 are suspended, the signal receiving module 1, the positive control module 2, the control module 3 and the negative control module 4 are all in the cut-off state, the positive control module 2 blocks the positive electrode of the battery from the positive charging interface 5, and the negative control module 4 blocks the negative electrode of the battery from the negative charging interface 6, thereby isolating the voltage at both ends of the battery from the positive charging interface 5 and the negative charging interface 6, preventing leakage at the positive charging interface 5 and the negative charging interface 6, and avoiding the metal charging interface from being corroded by electrolysis reaction in water, thereby effectively improving the service life of the battery.

[0044] The above description is only an embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention shall be included in the scope of the claims of the present invention.

Claims

1. A protection circuit for a battery pack charging interface, characterized in that: include: A signal receiving module (1), a positive control module (2), a control module (3), a negative control module (4), a positive charging interface (5), a negative charging interface (6) and a KEY interface (7), wherein the signal receiving module (1) has a first signal receiving end (11), a second signal receiving end (12) and a third signal receiving end (13), the positive control module (2) has a first positive control end (21), a second positive control end (22) and a third positive control end (23), the control module (3) has a first control end (31), a second control end (32) and a third control end (33), the negative control module (4) has a first negative control end (41), a second negative control end (42) and a third positive control end (23), ) and a third negative electrode control terminal (43), the first signal receiving terminal (11) is connected to the KEY interface (7), the second signal receiving terminal (12) is connected to the first positive electrode control terminal (21), the third signal receiving terminal (13) is connected to the first control terminal (31), the second positive electrode control terminal (22) is connected to the positive electrode charging interface (5), the third positive electrode control terminal (23) is connected to the positive electrode of the battery, the second control terminal (32) is connected to a power source, the third control terminal (33) is connected to the first negative electrode control terminal (41), the second negative electrode control terminal (42) is connected to the negative electrode charging interface (6), and the third negative electrode control terminal (43) is connected to the negative electrode of the battery.

2. The protection circuit of the battery pack charging interface according to claim 1, characterized in that: The signal receiving module (1) comprises a first control module (14) and a second control module (15), the first control module (14) and the second control module (15) are connected in series, the first control module (14) and the second control module (15) are respectively connected to the KEY interface (7), the other end of the first control module (14) is connected to the first positive control end (21), and the other end of the second control module (15) is connected to the first control end (31).

3. The protection circuit of the battery pack charging interface according to claim 1, characterized in that: The control module (3) comprises a MOS tube Q3, a resistor R7 and a resistor R8; the gate of the MOS tube Q3 is connected to the third signal receiving terminal (13) via the resistor R7; the source of the MOS tube Q3 is connected to a power supply; the drain of the MOS tube Q3 is connected to the first negative control terminal (41); one end of the resistor R8 is connected to the source of the MOS tube Q3, and the other end thereof is respectively connected to the gate of the MOS tube Q3 and the resistor R7.

4. The protection circuit of the battery pack charging interface according to claim 2, characterized in that: The signal receiving module (1) further comprises a voltage stabilizing diode Z1, wherein the anode of the voltage stabilizing diode Z1 is respectively connected to the first control module (14) and the second control module (15), and the cathode of the voltage stabilizing diode Z1 is connected to the KEY interface (7).

5. The protection circuit of the battery pack charging interface according to claim 1, characterized in that: The positive electrode control module (2) comprises a MOS tube Q2, a resistor R1 and a resistor R2, the drain of the MOS tube Q2 is connected to the positive electrode charging interface (5), the source of the MOS tube Q2 is connected to the positive electrode of the battery, the gate of the MOS tube Q2 is connected to the second signal receiving end (12) via the resistor R2, and the resistor R2 is connected between the gate of the MOS tube Q2 and the source of the MOS tube Q2.

6. The protection circuit of the battery pack charging interface according to claim 1, characterized in that: The negative electrode control module (4) comprises a MOS tube Q1, a resistor R9 and a resistor R10, the source of the MOS tube Q1 is connected to the negative electrode charging interface (6), the gate of the MOS tube Q1 is connected to the third control terminal (33) via the resistor R9, the source of the MOS tube Q1 is connected to the negative electrode of the battery, one end of the resistor R10 and the drain of the MOS tube Q1 are connected to the negative electrode charging interface (6), and the other end thereof is respectively connected to the gate of the MOS tube Q1 and the resistor R9.

7. The protection circuit of the battery pack charging interface according to claim 2, characterized in that: The first control module (14) comprises a transistor Q4, a resistor R3 and a resistor R4, the drain of the transistor Q4 is connected to the first positive control terminal (21), the gate of the transistor Q4 is connected to the KEY interface (7) through the resistor R4 and the second control module (15), and the gate of the transistor Q4 is connected to the ground through the resistor R3 and the source of the transistor Q4.

8. The protection circuit of the battery pack charging interface according to claim 7, characterized in that: The second control module (15) comprises a transistor Q5, a resistor R5 and a resistor R6; the gate of the transistor Q5 is connected to the KEY interface (7) through the resistor R5 and the first control module (14); the drain of the transistor Q5 is connected to the first control terminal (31); the gate of the transistor Q5 is grounded through the resistor R6 and the source of the transistor Q5.

9. A battery pack, characterized in that: A protection circuit for a battery pack charging interface comprising any one of claims 1-8.

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