Lithium battery overvoltage protection circuit

Abstract

The utility model discloses a kind of lithium battery overvoltage protection circuit, the first current end of fusible three-terminal fuse is connected through temperature protection circuit and the positive terminal B+ of battery, temperature protection circuit includes temperature switch, triode Q1, resistance R11, resistance R12, resistance R13 and MOS tube Q1;The input end of second switch tube is connected fusible three-terminal fuse, the output end of second switch tube is connected temperature switch, and temperature switch connects the positive terminal B+ of battery;The input end of second switch tube is connected the control end of second switch tube through resistance R13, and the control end of second switch tube is connected with the input end of first switch tube, and the output end of first switch tube is grounded, and the control end of first switch tube is grounded, and resistance R11 connects the GPIO pin of MCU, and resistance R11 connects the control end of first switch tube;It can be quickly powered off when fuse control circuit fails, cut off charging input end C+ to the charging loop of battery positive terminal B+, stop charging, ensure the reliability and stability of overvoltage protection.

Description

Technical Field

[0001] This utility model relates to the field of lithium battery overvoltage protection circuit technology, and in particular to a lithium battery overvoltage protection circuit. Background Technology

[0002] On construction sites, various construction workers use a variety of small or miniature construction tools, such as hammers, scissors, trowels, small electric drills, trowels, bolts, screws, nails, and other construction tools. Generally, workers carry toolboxes to carry these tools for easy access.

[0003] Therefore, toolboxes are essential for people working outdoors, ensuring that tools are not scattered. However, existing toolboxes are generally limited in function, serving only a storage purpose.

[0004] Therefore, in this utility model application, the applicant has carefully researched and developed a lithium battery overvoltage protection circuit to solve the above-mentioned problems. Utility Model Content

[0005] In view of this, the present invention addresses the deficiencies of the existing technology, and its main purpose is to provide a lithium battery overvoltage protection circuit that can quickly cut off power when the fuse control circuit fails, disconnect the charging circuit from the charging input terminal C+ to the positive terminal B+ of the battery, stop charging, and ensure the reliability and stability of overvoltage protection.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A lithium battery overvoltage protection circuit includes a fusible three-terminal fuse and a fuse control circuit; the first current terminal of the fusible three-terminal fuse is connected to the positive terminal B+ of the battery, the second current terminal of the fusible three-terminal fuse is connected to the charging input terminal C+, the input terminal of the fuse control circuit is connected to the overvoltage protection control terminal CHG of the protection IC, and its output terminal is connected to the fuse control terminal of the fusible three-terminal fuse;

[0008] The first current terminal of the fusible three-terminal fuse is connected to the positive terminal B+ of the battery through a temperature protection circuit. The temperature protection circuit includes a temperature switch, a transistor Q1, resistors R11, R12, and R13, and a MOSFET Q1.

[0009] The input terminal of the second switching transistor is connected to the first current terminal of the three-terminal fuse. The output terminal of the second switching transistor is connected to one end of the temperature switch, and the other end of the temperature switch is connected to the positive terminal B+ of the battery. The input terminal of the second switching transistor is also connected to the control terminal of the second switching transistor through resistor R13. The control terminal of the second switching transistor is connected to the input terminal of the first switching transistor. The output terminal of the first switching transistor is grounded. The control terminal of the first switching transistor is grounded through resistor R12. One end of resistor R11 is used to connect to the GPIO pin of the MCU, and the other end of resistor R11 is connected to the control terminal of the first switching transistor.

[0010] As a preferred embodiment, the first switching transistor is a transistor Q1, the collector of the transistor Q1 is the input terminal of the first switching transistor, the emitter of the transistor Q1 is the output terminal of the first switching transistor, and the base of the transistor Q1 is the control terminal of the first switching transistor.

[0011] As a preferred embodiment, the second switch is a MOSFET Q1, with the source of the MOSFET Q1 being the input terminal of the second switch, the drain of the MOSFET Q1 being the output terminal of the second switch, and the gate of the MOSFET Q1 being the control terminal of the second switch.

[0012] As a preferred embodiment, the input terminal of the fuse control circuit is connected to the overvoltage protection control terminal CHG of the protection IC via a failure control circuit.

[0013] Compared with the prior art, this utility model has obvious advantages and beneficial effects. Specifically, as can be seen from the above technical solution:

[0014] Its main function is to connect a temperature protection circuit in series between the fusible three-terminal fuse and the positive terminal B+ of the battery. This allows for rapid power cut-off when the fuse control circuit fails, cutting off the charging circuit from the charging input terminal C+ to the positive terminal B+ of the battery, stopping charging, and ensuring the reliability and stability of overvoltage protection.

[0015] Secondly, through the failure control circuit, when the protection IC fails and cannot perform voltage detection, the charging circuit from the charging input terminal C+ to the positive terminal B+ of the battery can be cut off in time, stopping the charging and further ensuring the reliability and stability of the overvoltage protection.

[0016] Furthermore, the overall circuit structure is cleverly and reasonably designed to ensure the stability and reliability of the toolbox during use.

[0017] To more clearly illustrate the structural features and effects of this utility model, the following detailed description of this utility model is provided in conjunction with the accompanying drawings and specific embodiments. Attached Figure Description

[0018] Figure 1 This is a general control principle block diagram of a preferred embodiment of the present invention;

[0019] Figure 2 This is a circuit diagram of a preferred embodiment of the present invention;

[0020] Explanation of reference numerals in the attached diagram:

[0021] 11. Fuseable three-terminal fuse 12. Fuse control circuit

[0022] 13. Failure control circuit

[0023] 14. Temperature protection circuit 141. Temperature switch. Detailed Implementation

[0024] Please refer to Figure 1 and Figure 2 As shown, it illustrates the specific structure of a preferred embodiment of the present invention, which is a lithium battery overvoltage protection circuit, including a fusible three-terminal fuse 11 and a fuse control circuit 12.

[0025] The first current terminal of the fusible three-terminal fuse 11 is connected to the positive terminal B+ of the battery, the second current terminal of the fusible three-terminal fuse 11 is connected to the charging input terminal C+, the input terminal of the fuse control circuit 12 is connected to the overvoltage protection control terminal CHG of the protection IC, and its output terminal is connected to the fuse control terminal of the fusible three-terminal fuse 11.

[0026] In this embodiment, the input terminal of the fuse control circuit 12 is connected to the overvoltage protection control terminal CHG of the protection IC via the failure control circuit 13. Preferably, the failure control circuit 13 includes a MOSFET Q3, resistors R1 and R2, and a Zener diode ZD1.

[0027] The positive terminal of Zener diode ZD1 is grounded, and the negative terminal of Zener diode ZD1 is connected to the gate of MOSFET Q3. The gate of MOSFET Q3 is connected to the overvoltage protection control terminal CHG of the protection IC through resistor R1. The gate of MOSFET Q3 is also grounded through resistor R2. The source of MOSFET Q3 is grounded, and the drain of MOSFET Q3 is connected to the input terminal of fuse control circuit 12.

[0028] In this embodiment, the fuse control circuit 12 includes a MOSFET Q4, resistors R3 and R4, diode D12, and diode D22. The drain of MOSFET Q4 is connected to the cathode of diode D22, the anode of diode D22 is connected to the fuse control terminal of the three-terminal fuse 11, the source of MOSFET Q4 is grounded, the gate of MOSFET Q4 is grounded through resistor R4, the cathode of diode D12 is connected to the gate of MOSFET Q4, the anode of diode D12 and one end of resistor R3 are connected to the drain of MOSFET Q3, and the other end of resistor R3 is connected to the second current terminal of the three-terminal fuse 11.

[0029] The first current terminal of the fusible three-terminal fuse 11 is connected to the positive terminal B+ of the battery through the temperature protection circuit 14. The temperature protection circuit 14 includes a temperature switch 141, a transistor Q1, resistors R11, R12, and R13, and a MOSFET Q1.

[0030] The input terminal of the second switch is connected to the first current terminal of the three-terminal fuse 11, and the output terminal of the second switch is connected to one end of the temperature switch 141. The other end of the temperature switch 141 is connected to the positive terminal B+ of the battery. The input terminal of the second switch is also connected to the control terminal of the second switch through resistor R13. The control terminal of the second switch is connected to the input terminal of the first switch.

[0031] In this embodiment, the second switch is a MOS transistor Q1, the source of the MOS transistor Q1 is the input terminal of the second switch, the drain of the MOS transistor Q1 is the output terminal of the second switch, and the gate of the MOS transistor Q1 is the control terminal of the second switch.

[0032] The output terminal of the first switching transistor is grounded, and the control terminal of the first switching transistor is grounded through resistor R12. One end of resistor R11 is used to connect to the GPIO pin of the MCU, and the other end of resistor R11 is connected to the control terminal of the first switching transistor. In this embodiment, the first switching transistor is transistor Q1, the collector of transistor Q1 is the input terminal of the first switching transistor, the emitter of transistor Q1 is the output terminal of the first switching transistor, and the base of transistor Q1 is the control terminal of the first switching transistor.

[0033] The working principle will be explained in general terms below:

[0034] When the battery management system's overvoltage protection IC is working normally during charging, the control signal output from the overvoltage protection control terminal CHG of the protection IC is at a high level. At this time, the gate of MOSFET Q3 is at a high level, MOSFET Q3 is in the conducting state, the positive terminal of diode D1 is at a low level, the gate of MOSFET Q4 is pulled down to a low level by resistor R4, MOSFET Q4 is in the cut-off state, the fuse control terminal of the three-terminal fuse 11 (also known as F1 in the figure) is at a high level, the three-terminal fuse 11 (also known as F1 in the figure) is not triggered to blow, at the same time, the MCU's GPIO pin outputs a high level, turning on transistor Q1, turning on MOSFET Q2, and the temperature switch is in the normally conducting state, thereby realizing the connection between the positive terminal B+ of the battery and the charging input terminal C+, thus realizing the charging of the battery;

[0035] When the lithium battery is overcharged but has not reached the operating temperature of the temperature switch 141, the control signal output by the overvoltage protection control terminal CHG of the protection IC is low. At this time, the gate of MOSFET Q3 is low, and MOSFET Q3 is in the off state. The positive terminal of diode D12 is pulled up to a high level through resistor R3, and the gate of MOSFET Q4 is also high, and MOSFET Q4 is in the conducting state. The fuse control terminal of the three-terminal fuse 11 (also known as F1 in the figure) is set to a low level through diode D22 and MOSFET Q4. The internal heating wire of the three-terminal fuse 11 (also known as F1 in the figure) is triggered to blow, cutting off the charging circuit from the charging input terminal C+ to the positive terminal B+ of the battery, stopping charging, and realizing overvoltage protection.

[0036] When the fuse control circuit 12 fails and the operating temperature of the temperature switch 141 is reached, the temperature switch opens, cutting off the charging circuit from the charging input terminal C+ to the positive terminal B+ of the battery, stopping charging, and realizing overvoltage protection.

[0037] When the lithium battery does not need to be charged, the MCU's GPIO pin outputs a low level, turning off transistor Q1, cutting off MOSFET Q2, and disconnecting the temperature switch from diode D3, thus disabling the temperature protection circuit 14.

[0038] When the protection IC fails and cannot detect voltage, the overvoltage protection control terminal CHG of the protection IC has no output control signal. At this time, the gate of MOSFET Q3 is pulled down to a low level through resistor R2, and MOSFET Q3 is in the off state. The positive terminal of diode D1 is pulled up to a high level through resistor R3, and the gate of MOSFET Q4 is also at a high level, and MOSFET Q4 is in the conducting state. The fuse control terminal of the three-terminal fuse 11 (also known as F1 in the figure) is set to a low level through diode D22 and MOSFET Q4. The internal heating wire of the three-terminal fuse 11 (also known as F1 in the figure) is triggered to blow, cutting off the charging circuit from the charging input terminal C+ to the positive terminal B+ of the battery, stopping charging, and realizing overvoltage protection.

[0039] The key design feature of this utility model is that it connects a temperature protection circuit in series between the fusible three-terminal fuse and the positive terminal B+ of the battery. This allows for rapid power cut-off when the fuse control circuit fails, cutting off the charging circuit from the charging input terminal C+ to the positive terminal B+ of the battery, stopping charging, and ensuring the reliability and stability of overvoltage protection.

[0040] Secondly, through the failure control circuit, when the protection IC fails and cannot perform voltage detection, the charging circuit from the charging input terminal C+ to the positive terminal B+ of the battery can be cut off in time, stopping the charging and further ensuring the reliability and stability of the overvoltage protection.

[0041] Furthermore, the overall circuit structure is cleverly and reasonably designed to ensure the stability and reliability of the toolbox during use.

[0042] The above description is merely a preferred embodiment of the present utility model and does not constitute any limitation on the technical scope of the present utility model. Therefore, any minor modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present utility model shall still fall within the scope of the technical solution of the present utility model.

Claims

1. A lithium battery overvoltage protection circuit, comprising a fusible three-terminal fuse and a fuse control circuit; the first current terminal of the fusible three-terminal fuse is connected to the positive terminal B+ of the battery, the second current terminal of the fusible three-terminal fuse is connected to the charging input terminal C+, the input terminal of the fuse control circuit is connected to the overvoltage protection control terminal CHG of a protection IC, and its output terminal is connected to the fuse control terminal of the fusible three-terminal fuse; characterized in that: The first current terminal of the fusible three-terminal fuse is connected to the positive terminal B+ of the battery through a temperature protection circuit. The temperature protection circuit includes a temperature switch, a transistor Q1, resistors R11, R12, and R13, and a MOSFET Q1. The input terminal of the second switching transistor is connected to the first current terminal of the three-terminal fuse. The output terminal of the second switching transistor is connected to one end of the temperature switch, and the other end of the temperature switch is connected to the positive terminal B+ of the battery. The input terminal of the second switching transistor is also connected to the control terminal of the second switching transistor through resistor R13. The control terminal of the second switching transistor is connected to the input terminal of the first switching transistor. The output terminal of the first switching transistor is grounded. The control terminal of the first switching transistor is grounded through resistor R12. One end of resistor R11 is used to connect to the GPIO pin of the MCU, and the other end of resistor R11 is connected to the control terminal of the first switching transistor.

2. The lithium battery overvoltage protection circuit according to claim 1, characterized in that: The first switching transistor is a transistor Q1, the collector of the transistor Q1 is the input terminal of the first switching transistor, the emitter of the transistor Q1 is the output terminal of the first switching transistor, and the base of the transistor Q1 is the control terminal of the first switching transistor.

3. The lithium battery overvoltage protection circuit according to claim 1, characterized in that: The second switch is a MOSFET Q1, with the source of the MOSFET Q1 being the input terminal of the second switch, the drain of the MOSFET Q1 being the output terminal of the second switch, and the gate of the MOSFET Q1 being the control terminal of the second switch.

4. The lithium battery overvoltage protection circuit according to claim 1, characterized in that: The input terminal of the fuse control circuit is connected to the overvoltage protection control terminal CHG of the protection IC through the failure control circuit.

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