A lithium battery protection circuit and device

Abstract

The embodiment of the present invention discloses a lithium battery protection circuit and device, wherein the lithium battery protection circuit includes a lithium battery pack, an output protection circuit, a MOS tube, a first diode and a fuse, the positive output end of the lithium battery pack is connected to the input end of the output protection circuit, the positive output end of the lithium battery pack is also connected to the positive input end of the external load through the fuse, the negative input end of the external load is grounded and connected to the negative output end of the lithium battery pack, the ground end of the fuse is connected to the positive electrode of the first diode, the negative electrode of the first diode is connected to the drain of the MOS tube, the gate of the MOS tube is connected to the output end of the output protection circuit, and the source of the MOS tube is grounded; when the output protection circuit detects that the lithium battery pack is overcurrent or overvoltage, the output end of the output protection circuit outputs a high level to turn on the MOS tube, and the ground end of the fuse is grounded, turned on and blown to cut off the power of the external load. The embodiment of the present invention can effectively protect the lithium battery, reduce the damage caused to the lithium battery by overvoltage or overcurrent, and improve the service life of the lithium battery.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium batteries, and in particular to a lithium battery protection circuit and device. Background Art

[0002] With the increase in the application of lithium-ion batteries, such as in smart phones, mobile power banks, power tools, vacuum cleaners, etc., users have increased their requirements for the safety performance of lithium batteries. Since lithium-ion batteries have high energy and high storage energy density, during the charging and discharging process, if the lithium-ion battery is overcharged and discharged, the lithium-ion battery body will generate a lot of heat, which will cause safety problems such as explosion and fire of lithium-ion batteries. Summary of the invention

[0003] The embodiments of the present invention provide a lithium battery protection circuit and device, which can effectively protect the lithium battery, reduce the damage to the lithium battery caused by overvoltage or overcurrent, and improve the service life of the lithium battery and the user experience.

[0004] In a first aspect, an embodiment of the present invention provides a lithium battery protection circuit, comprising:

[0005] A lithium battery pack, an output protection circuit, a MOS tube, a first diode and a fuse, wherein the positive output end of the lithium battery pack is connected to the input end of the output protection circuit, the positive output end of the lithium battery pack is also connected to the positive input end of an external load through a fuse, the negative input end of the external load is grounded and connected to the negative output end of the lithium battery pack, the ground end of the fuse is connected to the positive electrode of the first diode, the negative electrode of the first diode is connected to the drain of the MOS tube, the gate of the MOS tube is connected to the output end of the output protection circuit, and the source of the MOS tube is grounded; when the output protection circuit detects that the lithium battery pack is overcurrent or overvoltage, the output end of the output protection circuit outputs a high level to turn on the MOS tube, and the ground end of the fuse is grounded, turned on and blown to cut off power to the external load.

[0006] Furthermore, the output protection circuit includes a first output protection module and a second output protection module, the lithium battery pack includes a first lithium battery group and a second lithium battery group connected in series, the first lithium battery group and the second lithium battery group each include a plurality of lithium batteries; the positive output ends of all lithium batteries in the first lithium battery group are connected to the input end of the first output protection module, and the positive output end of one of the lithium batteries in the first lithium battery group is also connected to the positive input end of the external load through a fuse; the positive output ends of all lithium batteries in the second lithium battery group are connected to the input end of the second output protection module, the positive output end of one of the lithium batteries in the second lithium battery group is also connected to the input end of the first output protection module, and the negative output end of the second lithium battery group is also connected to the negative input end of the external load; the output end of the first output protection module and the output end of the second output protection module are both connected to the gate of the MOS tube.

[0007] Further, the first output protection module includes a first protection chip, a switch tube, a first triode, a second diode, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor and a fourteenth resistor, and the first lithium battery group includes a first lithium battery, a second lithium battery and a third lithium battery connected in series with each other; the positive output end of the first lithium battery is connected to the first detection end of the first protection chip through the first resistor, the positive output end of the second lithium battery is connected to the second detection end of the first protection chip through the second resistor, the positive output end of the third lithium battery is connected to the third detection end of the first protection chip through the third resistor, and the positive output end of the first lithium battery is connected to the positive detection end of the first protection chip through the sixth resistor. The power input end is connected to the emitter of the first triode, the positive output end of the first lithium battery is connected to the base of the first triode through the sixth resistor and the seventh resistor in sequence, the base of the first triode is also connected to the drain of the switch tube through the fifth resistor, the positive output end of the first lithium battery is also connected to the positive input end of the external load through a fuse, the collector of the first triode is connected to the gate of the MOS tube through the fourteenth resistor, the output end of the first protection chip is connected to the gate of the switch tube through the fourth resistor, the source of the switch tube is connected to the ground end of the first protection chip and the output end of the second output protection module, and the output end of the second output protection module is also connected to the power input end of the first protection chip through the second diode.

[0008] Further, the second output protection module includes an eighth resistor, a ninth resistor, a tenth resistor, an eleventh resistor, a twelfth resistor, a thirteenth resistor, a third diode, a fourth diode and a second protection chip, the second lithium battery group includes a fourth lithium battery, a fifth lithium battery, a sixth lithium battery and a seventh lithium battery connected in series with each other, the positive output end of the fourth lithium battery is connected to the first detection end of the second protection chip through the eighth resistor, the positive output end of the fifth lithium battery is connected to the second detection end of the second protection chip through the ninth resistor, the positive output end of the sixth lithium battery is connected to the third detection end of the second protection chip through the tenth resistor, the positive output end of the seventh lithium battery is connected to the fourth detection end of the second protection chip through the eleventh resistor, the positive output end of the fourth lithium battery is also connected to the power input end of the second protection chip through the thirteenth resistor, the positive output end of the fourth lithium battery is also electrically connected to the source of the switch tube, the ground end of the second protection chip is grounded, the ground end of the second protection chip is also connected to the power input end of the second protection chip through the third diode, and the output end of the second protection chip is connected to the gate of the MOS tube through the twelfth resistor and the fourth diode in sequence.

[0009] Furthermore, the output protection circuit also includes a third output protection module, which includes an overcurrent and overvoltage detection chip, a fifteenth resistor, a sixteenth resistor, a seventeenth resistor, a first capacitor, a fifth diode, and a second transistor. The input end of the overcurrent and overvoltage detection chip is connected to the positive output end of the lithium battery pack, and the output end of the overcurrent and overvoltage detection chip is connected to the base of the second transistor through the fifteenth resistor, the first capacitor, the fifth diode, and the sixteenth resistor in sequence. The collector of the second transistor is connected to the base of the first transistor through the seventeenth resistor, and the base of the first transistor is also connected to the drain of the switch tube through the fifth resistor, and the emitter of the second transistor is grounded.

[0010] In the second aspect, an embodiment of the present invention further provides a lithium battery protection device, comprising a lithium battery protection circuit and an external device, wherein the lithium battery protection circuit comprises a lithium battery pack, an output protection circuit, a MOS tube, a first diode and a fuse, wherein the positive output end of the lithium battery pack is connected to the input end of the output protection circuit, and the positive output end of the lithium battery pack is also connected to the positive input end of an external load through a fuse, the negative input end of the external load is grounded and connected to the negative output end of the lithium battery pack, the ground end of the fuse is connected to the positive electrode of the first diode, the negative electrode of the first diode is connected to the drain of the MOS tube, the gate of the MOS tube is connected to the output end of the output protection circuit, and the source of the MOS tube is grounded; when the output protection circuit detects that the lithium battery pack is overcurrent or overvoltage, the output end of the output protection circuit outputs a high level to turn on the MOS tube, and the ground end of the fuse is grounded, turned on and blown to cut off power to the external load.

[0011] Furthermore, the output protection circuit includes a first output protection module and a second output protection module, the lithium battery pack includes a first lithium battery group and a second lithium battery group connected in series, the first lithium battery group and the second lithium battery group each include a plurality of lithium batteries; the positive output ends of all lithium batteries in the first lithium battery group are connected to the input end of the first output protection module, and the positive output end of one of the lithium batteries in the first lithium battery group is also connected to the positive input end of the external load through a fuse; the positive output ends of all lithium batteries in the second lithium battery group are connected to the input end of the second output protection module, the positive output end of one of the lithium batteries in the second lithium battery group is also connected to the input end of the first output protection module, and the negative output end of the second lithium battery group is also connected to the negative input end of the external load; the output end of the first output protection module and the output end of the second output protection module are both connected to the gate of the MOS tube.

[0012] Further, the first output protection module includes a first protection chip, a switch tube, a first triode, a second diode, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor and a fourteenth resistor, and the first lithium battery group includes a first lithium battery, a second lithium battery and a third lithium battery connected in series with each other; the positive output end of the first lithium battery is connected to the first detection end of the first protection chip through the first resistor, the positive output end of the second lithium battery is connected to the second detection end of the first protection chip through the second resistor, the positive output end of the third lithium battery is connected to the third detection end of the first protection chip through the third resistor, and the positive output end of the first lithium battery is connected to the positive detection end of the first protection chip through the sixth resistor. The power input end is connected to the emitter of the first triode, the positive output end of the first lithium battery is connected to the base of the first triode through the sixth resistor and the seventh resistor in sequence, the base of the first triode is also connected to the drain of the switch tube through the fifth resistor, the positive output end of the first lithium battery is also connected to the positive input end of the external load through a fuse, the collector of the first triode is connected to the gate of the MOS tube through the fourteenth resistor, the output end of the first protection chip is connected to the gate of the switch tube through the fourth resistor, the source of the switch tube is connected to the ground end of the first protection chip and the output end of the second output protection module, and the output end of the second output protection module is also connected to the power input end of the first protection chip through the second diode.

[0013] Further, the second output protection module includes an eighth resistor, a ninth resistor, a tenth resistor, an eleventh resistor, a twelfth resistor, a thirteenth resistor, a third diode, a fourth diode and a second protection chip, the second lithium battery group includes a fourth lithium battery, a fifth lithium battery, a sixth lithium battery and a seventh lithium battery connected in series with each other, the positive output end of the fourth lithium battery is connected to the first detection end of the second protection chip through the eighth resistor, the positive output end of the fifth lithium battery is connected to the second detection end of the second protection chip through the ninth resistor, the positive output end of the sixth lithium battery is connected to the third detection end of the second protection chip through the tenth resistor, the positive output end of the seventh lithium battery is connected to the fourth detection end of the second protection chip through the eleventh resistor, the positive output end of the fourth lithium battery is also connected to the power input end of the second protection chip through the thirteenth resistor, the positive output end of the fourth lithium battery is also electrically connected to the source of the switch tube, the ground end of the second protection chip is grounded, the ground end of the second protection chip is also connected to the power input end of the second protection chip through the third diode, and the output end of the second protection chip is connected to the gate of the MOS tube through the twelfth resistor and the fourth diode in sequence.

[0014] Furthermore, the output protection circuit also includes a third output protection module, which includes an overcurrent and overvoltage detection chip, a fifteenth resistor, a sixteenth resistor, a seventeenth resistor, a first capacitor, a fifth diode, and a second transistor. The input end of the overcurrent and overvoltage detection chip is connected to the positive output end of the lithium battery pack, and the output end of the overcurrent and overvoltage detection chip is connected to the base of the second transistor through the fifteenth resistor, the first capacitor, the fifth diode, and the sixteenth resistor in sequence. The collector of the second transistor is connected to the base of the first transistor through the seventeenth resistor, and the base of the first transistor is also connected to the drain of the switch tube through the fifth resistor, and the emitter of the second transistor is grounded.

[0015] The embodiments of the present invention can effectively protect lithium batteries, reduce the damage to lithium batteries caused by overvoltage or overcurrent, and improve the service life of lithium batteries and the user experience. Furthermore, through the design of the composite protection circuit, the protection performance of the lithium battery is more perfect. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying any creative work.

[0017] Figure 1 is a module diagram of a lithium battery protection circuit provided by an embodiment of the present invention;

[0018] Figure 2 It is a circuit diagram of a lithium battery protection circuit provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0021] It should also be understood that the terms used in this specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the specification of the present invention and the appended claims, the singular forms of "a", "an" and "the" are intended to include the plural forms unless the context clearly indicates otherwise. It should also be further understood that the term "and / or" used in the specification of the present invention and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes these combinations.

[0022] See also Figure 1 and Figure 2 , is a cross-sectional module diagram of a lithium battery protection circuit provided by an embodiment of the present invention, wherein the lithium battery protection circuit 1 comprises a lithium battery pack 10, an output protection circuit 20, a MOS tube 30, a first diode 40 and a fuse 50, wherein the positive output terminal of the lithium battery pack 10 is connected to the input terminal of the output protection circuit 20, and the positive output terminal of the lithium battery pack 10 is also connected to the positive input terminal of the external load 2 through the fuse 50, the negative input terminal of the external load 2 is grounded and connected to the negative output terminal of the lithium battery pack 10, and the ground terminal of the fuse 50 is connected to the first The positive electrode of the diode 40 (or D15) is connected, the negative electrode of the first diode 40 is connected to the drain of the MOS tube 30 (or Q14), the gate of the MOS tube 30 is connected to the output end of the output protection circuit 20, and the source of the MOS tube 30 is grounded; when the output protection circuit 20 detects that the lithium battery pack 10 is overcurrent or overvoltage, the output end of the output protection circuit 20 outputs a high level to turn on the MOS tube 30, and the ground end of the fuse 50 (or F2) is grounded, turned on and blown to cut off the power to the external load 2.

[0023] Among them, the lithium battery pack 10 may include a plurality of lithium batteries. The output protection circuit 20 can realize overcurrent and overvoltage protection for the lithium battery pack 20. Specifically, when the output protection circuit 20 detects that any battery in the lithium battery pack 20 is overcurrent or overvoltage, the output end of the output protection circuit 20 outputs a high level, so that the MOS tube 30 is turned on, and the ground end of the fuse 50 is grounded through the first diode 40. At this time, the fuse 50 is blown, and the external load 2 is powered off and no longer works, thereby protecting not only the lithium battery pack 10, but also the external load 2. If the lithium battery pack is powered normally, the output protection circuit 20 generates a low level, and the MOS tube Q14 is turned off, and the ground end of the fuse F2 is not grounded. At this time, the lithium battery pack normally supplies power to the external device. As an option, the first diode D15 can be a rectifier diode. In addition, the gate of the MOS tube Q14 is also grounded through an eighteenth resistor R70. The gate of the MOS tube Q14 is also grounded through a second capacitor C46, ​​thereby ensuring the stability of the current and voltage of the entire lithium battery protection circuit.

[0024] In one embodiment, the output protection circuit 20 includes a first output protection module 21 and a second output protection module 22, the lithium battery pack 10 includes a first lithium battery group 11 and a second lithium battery group 12 connected in series, and the first lithium battery group 11 and the second lithium battery group 12 each include a plurality of lithium batteries; the positive output ends of all lithium batteries in the first lithium battery group 11 are connected to the input end of the first output protection module 21, and the positive output end of one of the lithium batteries in the first lithium battery group 11 is also connected to the positive input end of the external load 2 through a fuse 50; the positive output ends of all lithium batteries in the second lithium battery group 12 are connected to the input end of the second output protection module 22, the positive output end of one of the lithium batteries in the second lithium battery group 12 is also connected to the input end of the first output protection module 21, and the negative output end of the second lithium battery group 21 is also connected to the negative input end of the external load 2; the output end of the first output protection module 21 and the output end of the second output protection module 22 are both connected to the gate G of the MOS tube 30.

[0025] The output protection circuit 20 may include two protection modules, namely a first output protection module 21 and a second output protection module 22. Accordingly, the lithium battery pack 10 may include a first lithium battery group 11 and a second lithium battery group 12 connected in series, wherein the first output protection module 21 is used to protect the first lithium battery group 11, and the second output protection module 22 is used to protect the second lithium battery group 12. Of course, in this embodiment, the output protection circuit 20 may also be divided into a plurality of protection modules. Similarly, the lithium battery pack 10 may also be divided into a plurality of lithium battery groups, and the number of lithium battery groups is not greater than the number of the protection modules.

[0026] Specifically, the first output protection module 21 is used to detect whether the first lithium battery pack 11 has overcurrent or overvoltage. If so, a high level is generated and output to the MOS tube Q14, so that the MOS tube Q14 is turned on, and the ground terminal of the fuse F2 is grounded and melted, and the lithium battery pack 10 is protected at this time; if not, a low level is generated, and the MOS tube Q14 is turned off, and the ground terminal of the fuse F2 is not grounded, and the lithium battery pack normally supplies power to the external device. Similarly, the second output protection module 22 is used to detect whether the second lithium battery pack 12 has overcurrent or overvoltage. If so, a high level is generated and output to the MOS tube Q14, so that the MOS tube Q14 is turned on, and the ground terminal of the fuse F2 is grounded and melted, and the lithium battery pack 10 is protected at this time; if not, a low level is generated, and the MOS tube Q14 is turned off, and the ground terminal of the fuse F2 is not grounded, and the lithium battery pack normally supplies power to the external device.

[0027] In one embodiment, the first output protection module 21 includes a first protection chip U3, a switch tube Q11, a first transistor Q7, a second diode Z4, a first resistor R11, a second resistor R16, a third resistor R24, a fourth resistor R52, a fifth resistor R50, a sixth resistor R25, a seventh resistor R37 and a fourteenth resistor R56. The first lithium battery group 11 includes a first lithium battery, a second lithium battery and a third lithium battery connected in series with each other; the positive output terminal B+ of the first lithium battery is connected to the first detection terminal V5 of the first protection chip U3 through the first resistor R11, the positive output terminal B6 of the second lithium battery is connected to the second detection terminal V2 of the first protection chip U3 through the second resistor R16, the positive output terminal B5 of the third lithium battery is connected to the third detection terminal V1 of the first protection chip U3 through the third resistor R24, and the positive output terminal B+ of the first lithium battery is connected to the first detection terminal V2 of the first protection chip U3 through the sixth resistor R25. The positive output terminal B+ of the first lithium battery is connected to the power input terminal VDD of the first protection chip U3 and the emitter E of the first transistor Q7, the positive output terminal B+ of the first lithium battery is connected to the base B of the first transistor Q7 through the sixth resistor R25 and the seventh resistor R37 in sequence, the base B of the first transistor Q7 is also connected to the drain D of the switch tube Q11 through the fifth resistor R50, the positive output terminal B+ of the first lithium battery is also connected to the positive input terminal of the external load through the fuse F2, the collector C of the first transistor Q7 is connected to the gate G of the MOS tube Q14 through the fourteenth resistor R56, the output terminal OUT of the first protection chip U3 is connected to the gate G of the switch tube Q11 through the fourth resistor R52, the source S of the switch tube Q11 is connected to the ground terminal VSS of the first protection chip U3 and the output terminal of the second output protection module, and the output terminal of the second output protection module is also connected to the power input terminal VDD of the first protection chip U3 through the second diode Z4.

[0028] Among them, the power input terminal VDD of the first protection chip U3 works after being powered by the first lithium battery. If any detection terminal of the first protection chip U3 detects that the lithium battery is overcurrent or overvoltage, that is, the first detection terminal V5 of the first protection chip U3 detects that the first lithium battery is overcurrent or overvoltage, or the second detection terminal V2 of the first protection chip U3 detects that the second lithium battery is overcurrent or overvoltage, or the third detection terminal V1 of the first protection chip U3 detects that the third lithium battery is overcurrent or overvoltage, then the output terminal OUT of the first protection chip U3 outputs a high level, so that the switch tube Q11 and the first triode Q7 are turned on. At this time, the gate of the MOS tube Q14 also receives a high level accordingly, thereby achieving conduction. At this time, the ground terminal of the fuse F2 is grounded and blown, and the external load is powered off, thereby achieving protection of the lithium battery pack.

[0029] In one embodiment, the second output protection module 22 includes an eighth resistor R90, a ninth resistor R17, a tenth resistor R20, an eleventh resistor R21, a twelfth resistor R66, a thirteenth resistor R82, a third diode Z2, a fourth diode D13 and a second protection chip U4, the second lithium battery group 12 includes a fourth lithium battery, a fifth lithium battery, a sixth lithium battery and a seventh lithium battery connected in series, the positive output terminal B4 of the fourth lithium battery is connected to the first detection terminal V5 of the second protection chip U4 through the eighth resistor R90, the positive output terminal B3 of the fifth lithium battery is connected to the second detection terminal V3 of the second protection chip U4 through the ninth resistor R17, the positive output terminal B2 of the sixth lithium battery is connected to the second protection chip U4 through the tenth resistor R20. The positive output terminal B1 of the seventh lithium battery is connected to the fourth detection terminal V1 of the second protection chip U4 through the eleventh resistor R21, the positive output terminal B1 of the fourth lithium battery is also connected to the power input terminal of the second protection chip U4 through the thirteenth resistor R, the positive output terminal B4 of the fourth lithium battery is also electrically connected to the source S of the switch tube Q11, the ground terminal VSS of the second protection chip U4 is grounded, the ground terminal VSS of the second protection chip U4 is also connected to the power input terminal VDD of the second protection chip U4 through the third diode Z2, and the output terminal OUT of the second protection chip U4 is connected to the gate G of the MOS tube Q14 through the twelfth resistor R66 and the fourth diode D13 in sequence.

[0030] Among them, the power input terminal VDD of the second protection chip U4 works after being powered by the first lithium battery. If any detection terminal of the second protection chip U4 detects that the lithium battery is overcurrent or overvoltage, that is, the first detection terminal V5 of the second protection chip U4 detects that the fourth lithium battery is overcurrent or overvoltage, or the second detection terminal V3 of the second protection chip U4 detects that the fifth lithium battery is overcurrent or overvoltage, or the third detection terminal V2 of the second protection chip U4 detects that the sixth lithium battery is overcurrent or overvoltage, or the fourth detection terminal V1 of the second protection chip U4 detects that the seventh lithium battery is overcurrent or overvoltage, then the output terminal OUT of the second protection chip U4 outputs a high level, and the gate of the MOS tube Q14 also receives a high level accordingly, thereby achieving conduction. At this time, the ground terminal of the fuse F2 is grounded and blown, and the external load is powered off, thereby achieving protection of the lithium battery pack.

[0031] In one embodiment, the output protection circuit 20 also includes a third output protection module 23, which includes an overcurrent and overvoltage detection chip, a fifteenth resistor R86, a sixteenth resistor R63, a seventeenth resistor R43, a first capacitor C61, a fifth diode D6, and a second transistor Q16. The input end of the overcurrent and overvoltage detection chip is connected to the positive output end of the lithium battery pack, and the output end of the overcurrent and overvoltage detection chip is connected to the base B of the second transistor Q16 through the fifteenth resistor R86, the first capacitor C61, the fifth diode D6, and the sixteenth resistor R63 in sequence. The collector C of the second transistor Q16 is connected to the base B of the first transistor Q7 through the seventeenth resistor R43. The base B of the first transistor Q7 is also connected to the drain D of the switch tube Q11 through the fifth resistor R50, and the emitter E of the second transistor Q16 is grounded.

[0032] Among them, the overcurrent and overvoltage detection chip can detect whether the entire lithium battery pack 10 is overcurrent or overvoltage. If it is detected that the entire lithium battery pack 10 is overcurrent or overvoltage, a square wave can be output at this time to turn on the second transistor Q16. At this time, the first transistor Q7 is also turned on accordingly. At this time, the MOS tube Q14 is turned on, so the grounding end of the fuse F2 is grounded through the first diode D15, so that the fuse F2 is blown, that is, the lithium battery pack 10 is disconnected from the external load, thereby achieving protection for the lithium battery pack.

[0033] In summary, the embodiment of the present invention can effectively protect the lithium battery through the setting of the output protection circuit, reduce the damage to the lithium battery caused by overvoltage or overcurrent, and improve the service life of the lithium battery and the user experience. Furthermore, through the design of the further composite protection circuit, the protection performance of the lithium battery is further improved.

[0034] In a second aspect, an embodiment of the present invention further provides a lithium battery protection device, including a lithium battery protection circuit 101 and an external device 60, wherein the lithium battery protection circuit 1 includes a lithium battery pack 10, an output protection circuit 20, a MOS tube 30, a first diode 40 and a fuse 50, wherein the positive output end of the lithium battery pack 10 is connected to the input end of the output protection circuit 20, and the positive output end of the lithium battery pack 10 is also connected to the positive input end of the external load 2 through the fuse 50, and the negative input end of the external load 2 is grounded and connected to the negative output end of the lithium battery pack 10, The ground end of the fuse 50 is connected to the positive electrode of the first diode 40 (or D15), the negative electrode of the first diode 40 is connected to the drain of the MOS tube 30 (or Q14), the gate of the MOS tube 30 is connected to the output end of the output protection circuit 20, and the source of the MOS tube 30 is grounded; when the output protection circuit 20 detects that the lithium battery pack 10 is overcurrent or overvoltage, the output end of the output protection circuit 20 outputs a high level to turn on the MOS tube 30, and the ground end of the fuse 50 is grounded, turned on and blown to cut off the power to the external load 2.

[0035] Among them, the lithium battery pack 10 may include a plurality of lithium batteries. The output protection circuit 20 can realize overcurrent and overvoltage protection for the lithium battery pack 20. Specifically, when the output protection circuit 20 detects that any battery in the lithium battery pack 20 is overcurrent or overvoltage, the output end of the output protection circuit 20 outputs a high level, so that the MOS tube 30 is turned on, and the ground end of the fuse 50 is grounded through the first diode 40. At this time, the fuse 50 is blown, and the external load 2 is powered off and no longer works, thereby protecting not only the lithium battery pack 10, but also the external load 2. If the lithium battery pack is powered normally, the output protection circuit 20 generates a low level, and the MOS tube Q14 is turned off, and the ground end of the fuse F2 is not grounded. At this time, the lithium battery pack normally supplies power to the external device. As an option, the first diode D15 can be a rectifier diode. In addition, the gate of the MOS tube Q14 is also grounded through an eighteenth resistor R70. The gate of the MOS tube Q14 is also grounded through a second capacitor C46, ​​thereby ensuring the stability of the current and voltage of the entire lithium battery protection circuit.

[0036] In one embodiment, in one embodiment, the output protection circuit 20 includes a first output protection module 21 and a second output protection module 22, the lithium battery pack 10 includes a first lithium battery group 11 and a second lithium battery group 12 connected in series, the first lithium battery group 11 and the second lithium battery group 12 each include a plurality of lithium batteries; the positive output ends of all lithium batteries of the first lithium battery group 11 are connected to the input end of the first output protection module 21, and the positive output end of one of the lithium batteries of the first lithium battery group 11 is also connected to the positive input end of the external load 2 through a fuse 50; the positive output ends of all lithium batteries of the second lithium battery group 12 are connected to the input end of the second output protection module 22, the positive output end of one of the lithium batteries of the second lithium battery group 12 is also connected to the input end of the first output protection module 21, and the negative output end of the second lithium battery group 21 is also connected to the negative input end of the external load 2; the output end of the first output protection module 21 and the output end of the second output protection module 22 are both connected to the gate G of the MOS tube 30.

[0037] The output protection circuit 20 may include two protection modules, namely a first output protection module 21 and a second output protection module 22. Accordingly, the lithium battery pack 10 may include a first lithium battery group 11 and a second lithium battery group 12 connected in series, wherein the first output protection module 21 is used to protect the first lithium battery group 11, and the second output protection module 22 is used to protect the second lithium battery group 12. Of course, in this embodiment, the output protection circuit 20 may also be divided into a plurality of protection modules. Similarly, the lithium battery pack 10 may also be divided into a plurality of lithium battery groups, and the number of lithium battery groups is not greater than the number of the protection modules.

[0038] Specifically, the first output protection module 21 is used to detect whether the first lithium battery pack 11 has overcurrent or overvoltage. If so, a high level is generated and output to the MOS tube Q14, so that the MOS tube Q14 is turned on, and the ground terminal of the fuse F2 is grounded and melted, and the lithium battery pack 10 is protected at this time; if not, a low level is generated, and the MOS tube Q14 is turned off, and the ground terminal of the fuse F2 is not grounded, and the lithium battery pack normally supplies power to the external device. Similarly, the second output protection module 22 is used to detect whether the second lithium battery pack 12 has overcurrent or overvoltage. If so, a high level is generated and output to the MOS tube Q14, so that the MOS tube Q14 is turned on, and the ground terminal of the fuse F2 is grounded and melted, and the lithium battery pack 10 is protected at this time; if not, a low level is generated, and the MOS tube Q14 is turned off, and the ground terminal of the fuse F2 is not grounded, and the lithium battery pack normally supplies power to the external device.

[0039] In one embodiment, the first output protection module 21 includes a first protection chip U3, a switch tube Q11, a first transistor Q7, a second diode Z4, a first resistor R11, a second resistor R16, a third resistor R24, a fourth resistor R52, a fifth resistor R50, a sixth resistor R25, a seventh resistor R37 and a fourteenth resistor R56. The first lithium battery group 11 includes a first lithium battery, a second lithium battery and a third lithium battery connected in series with each other; the positive output terminal B+ of the first lithium battery is connected to the first detection terminal V5 of the first protection chip U3 through the first resistor R11, the positive output terminal B6 of the second lithium battery is connected to the second detection terminal V2 of the first protection chip U3 through the second resistor R16, the positive output terminal B5 of the third lithium battery is connected to the third detection terminal V1 of the first protection chip U3 through the third resistor R24, and the positive output terminal B+ of the first lithium battery is connected to the first detection terminal V2 of the first protection chip U3 through the sixth resistor R25. The positive output terminal B+ of the first lithium battery is connected to the power input terminal VDD of the first protection chip U3 and the emitter E of the first transistor Q7, the positive output terminal B+ of the first lithium battery is connected to the base B of the first transistor Q7 through the sixth resistor R25 and the seventh resistor R37 in sequence, the base B of the first transistor Q7 is also connected to the drain D of the switch tube Q11 through the fifth resistor R50, the positive output terminal B+ of the first lithium battery is also connected to the positive input terminal of the external load through the fuse F2, the collector C of the first transistor Q7 is connected to the gate G of the MOS tube Q14 through the fourteenth resistor R56, the output terminal OUT of the first protection chip U3 is connected to the gate G of the switch tube Q11 through the fourth resistor R52, the source S of the switch tube Q11 is connected to the ground terminal VSS of the first protection chip U3 and the output terminal of the second output protection module, and the output terminal of the second output protection module is also connected to the power input terminal VDD of the first protection chip U3 through the second diode Z4.

[0040] Among them, the power input terminal VDD of the first protection chip U3 works after being powered by the first lithium battery. If any detection terminal of the first protection chip U3 detects that the lithium battery is overcurrent or overvoltage, that is, the first detection terminal V5 of the first protection chip U3 detects that the first lithium battery is overcurrent or overvoltage, or the second detection terminal V2 of the first protection chip U3 detects that the second lithium battery is overcurrent or overvoltage, or the third detection terminal V1 of the first protection chip U3 detects that the third lithium battery is overcurrent or overvoltage, then the output terminal OUT of the first protection chip U3 outputs a high level, so that the switch tube Q11 and the first triode Q7 are turned on, and the gate of the MOS tube Q14 also receives a high level accordingly, thereby achieving conduction. At this time, the ground terminal of the fuse F2 is grounded and blown, and the external load is powered off, thereby achieving protection of the lithium battery pack.

[0041] In one embodiment, the second output protection module 22 includes an eighth resistor R90, a ninth resistor R17, a tenth resistor R20, an eleventh resistor R21, a twelfth resistor R66, a thirteenth resistor R82, a third diode Z2, a fourth diode D13 and a second protection chip U4, the second lithium battery group 12 includes a fourth lithium battery, a fifth lithium battery, a sixth lithium battery and a seventh lithium battery connected in series, the positive output terminal B4 of the fourth lithium battery is connected to the first detection terminal V5 of the second protection chip U4 through the eighth resistor R90, the positive output terminal B3 of the fifth lithium battery is connected to the second detection terminal V3 of the second protection chip U4 through the ninth resistor R17, the positive output terminal B2 of the sixth lithium battery is connected to the second protection chip U4 through the tenth resistor R20. The positive output terminal B1 of the seventh lithium battery is connected to the fourth detection terminal V1 of the second protection chip U4 through the eleventh resistor R21, the positive output terminal B1 of the fourth lithium battery is also connected to the power input terminal of the second protection chip U4 through the thirteenth resistor R, the positive output terminal B4 of the fourth lithium battery is also electrically connected to the source S of the switch tube Q11, the ground terminal VSS of the second protection chip U4 is grounded, the ground terminal VSS of the second protection chip U4 is also connected to the power input terminal VDD of the second protection chip U4 through the third diode Z2, and the output terminal OUT of the second protection chip U4 is connected to the gate G of the MOS tube Q14 through the twelfth resistor R66 and the fourth diode D13 in sequence.

[0042] Among them, the power input terminal VDD of the second protection chip U4 works after being powered by the first lithium battery. If any detection terminal of the second protection chip U4 detects that the lithium battery is overcurrent or overvoltage, that is, the first detection terminal V5 of the second protection chip U4 detects that the fourth lithium battery is overcurrent or overvoltage, or the second detection terminal V3 of the second protection chip U4 detects that the fifth lithium battery is overcurrent or overvoltage, or the third detection terminal V2 of the second protection chip U4 detects that the sixth lithium battery is overcurrent or overvoltage, or the fourth detection terminal V1 of the second protection chip U4 detects that the seventh lithium battery is overcurrent or overvoltage, then the output terminal OUT of the second protection chip U4 outputs a high level, and the gate of the MOS tube Q14 also receives a high level accordingly, thereby achieving conduction. At this time, the ground terminal of the fuse F2 is grounded and blown, and the external load is powered off, thereby achieving protection of the lithium battery pack.

[0043] In one embodiment, the output protection circuit 20 also includes a third output protection module 23, which includes an overcurrent and overvoltage detection chip, a fifteenth resistor R86, a sixteenth resistor R63, a seventeenth resistor R43, a first capacitor C61, a fifth diode D6, and a second transistor Q16. The input end of the overcurrent and overvoltage detection chip is connected to the positive output end of the lithium battery pack, and the output end of the overcurrent and overvoltage detection chip is connected to the base B of the second transistor Q16 through the fifteenth resistor R86, the first capacitor C61, the fifth diode D6, and the sixteenth resistor R63 in sequence. The collector C of the second transistor Q16 is connected to the base B of the first transistor Q7 through the seventeenth resistor R43. The base B of the first transistor Q7 is also connected to the drain D of the switch tube Q11 through the fifth resistor R50, and the emitter E of the second transistor Q16 is grounded.

[0044] Among them, the overcurrent and overvoltage detection chip can detect whether the entire lithium battery pack 10 is overcurrent or overvoltage. If it is detected that the entire lithium battery pack 10 is overcurrent or overvoltage, a square wave can be output at this time to turn on the second transistor Q16. At this time, the first transistor Q7 is also turned on accordingly. At this time, the MOS tube Q14 is turned on, so the grounding end of the fuse F2 is grounded through the first diode D15, so that the fuse F2 is blown, that is, the lithium battery pack 10 is disconnected from the external load, thereby achieving protection for the lithium battery pack.

[0045] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present invention, and these modifications or replacements should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A lithium battery protection circuit, It is characterized in that It includes a lithium battery pack, an output protection circuit, a MOS tube, a first diode and a fuse, wherein the positive output end of the lithium battery pack is connected to the input end of the output protection circuit, the positive output end of the lithium battery pack is also connected to the positive input end of an external load through a fuse, the negative input end of the external load is grounded and connected to the negative output end of the lithium battery pack, the ground end of the fuse is connected to the positive electrode of the first diode, the negative electrode of the first diode is connected to the drain of the MOS tube, the gate of the MOS tube is connected to the output end of the output protection circuit, and the source of the MOS tube is grounded; When the output protection circuit detects that the lithium battery pack is overcurrent or overvoltage, the output terminal of the output protection circuit outputs a high level to turn on the MOS tube, and the ground terminal of the fuse is grounded and turned on and blown to cut off the power to the external load; The output protection circuit includes a first output protection module and a second output protection module. The lithium battery pack includes a first lithium battery group and a second lithium battery group connected in series. The first lithium battery group and the second lithium battery group each include a plurality of lithium batteries. The positive output ends of all lithium batteries in the first lithium battery group are connected to the input end of the first output protection module. The positive output end of one of the lithium batteries in the first lithium battery group is also connected to the positive input end of an external load through a fuse. The positive output ends of all lithium batteries in the second lithium battery group are connected to the input end of the second output protection module. The positive output end of one of the lithium batteries in the second lithium battery group is also connected to the input end of the first output protection module. The negative output end of the second lithium battery group is also connected to the negative input end of the external load. The output end of the first output protection module and the output end of the second output protection module are both connected to the gate of the MOS tube. The first output protection module includes a first protection chip, a switch tube, a first triode, a second diode, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor and a fourteenth resistor. The first lithium battery group includes a first lithium battery, a second lithium battery and a third lithium battery connected in series. The positive output end of the first lithium battery is connected to the first detection end of the first protection chip through the first resistor, the positive output end of the second lithium battery is connected to the second detection end of the first protection chip through the second resistor, the positive output end of the third lithium battery is connected to the third detection end of the first protection chip through the third resistor, and the positive output end of the first lithium battery is connected to the power supply end of the first protection chip through the sixth resistor. The positive output end of the first lithium battery is connected to the base of the first triode through the sixth resistor and the seventh resistor in sequence, the base of the first triode is also connected to the drain of the switch tube through the fifth resistor, the positive output end of the first lithium battery is also connected to the positive input end of the external load through a fuse, the collector of the first triode is connected to the gate of the MOS tube through the fourteenth resistor, the output end of the first protection chip is connected to the gate of the switch tube through the fourth resistor, the source of the switch tube is connected to the ground end of the first protection chip and the output end of the second output protection module, and the output end of the second output protection module is also connected to the power input end of the first protection chip through the second diode; The second output protection module includes a second protection chip, and the output protection circuit also includes a third output protection module.

2. The lithium battery protection circuit as claimed in claim 1, It is characterized in that The second output protection module includes an eighth resistor, a ninth resistor, a tenth resistor, an eleventh resistor, a twelfth resistor, a thirteenth resistor, a third diode and a fourth diode. The second lithium battery group includes a fourth lithium battery, a fifth lithium battery, a sixth lithium battery and a seventh lithium battery connected in series. The positive output end of the fourth lithium battery is connected to the first detection end of the second protection chip through the eighth resistor, the positive output end of the fifth lithium battery is connected to the second detection end of the second protection chip through the ninth resistor, the positive output end of the sixth lithium battery is connected to the third detection end of the second protection chip through the tenth resistor, the positive output end of the seventh lithium battery is connected to the fourth detection end of the second protection chip through the eleventh resistor, the positive output end of the fourth lithium battery is also connected to the power input end of the second protection chip through the thirteenth resistor, the positive output end of the fourth lithium battery is also electrically connected to the source of the switch tube, the ground end of the second protection chip is grounded, the ground end of the second protection chip is also connected to the power input end of the second protection chip through the third diode, and the output end of the second protection chip is sequentially connected to the gate of the MOS tube through the twelfth resistor and the fourth diode.

3. The lithium battery protection circuit as claimed in claim 1, It is characterized in that The third output protection module includes an overcurrent and overvoltage detection chip, a fifteenth resistor, a sixteenth resistor, a seventeenth resistor, a first capacitor, a fifth diode, and a second transistor. The input end of the overcurrent and overvoltage detection chip is connected to the positive output end of the lithium battery pack, and the output end of the overcurrent and overvoltage detection chip is connected to the base of the second transistor through the fifteenth resistor, the first capacitor, the fifth diode, and the sixteenth resistor in sequence. The collector of the second transistor is connected to the base of the first transistor through the seventeenth resistor, and the base of the first transistor is also connected to the drain of the switch tube through the fifth resistor, and the emitter of the second transistor is grounded.

4. A lithium battery protection device, It is characterized in that It includes a lithium battery protection circuit and an external device, wherein the lithium battery protection circuit includes a lithium battery pack, an output protection circuit, a MOS tube, a first diode and a fuse, wherein the positive output end of the lithium battery pack is connected to the input end of the output protection circuit, the positive output end of the lithium battery pack is also connected to the positive input end of an external load through a fuse, the negative input end of the external load is grounded and connected to the negative output end of the lithium battery pack, the ground end of the fuse is connected to the positive electrode of the first diode, the negative electrode of the first diode is connected to the drain of the MOS tube, the gate of the MOS tube is connected to the output end of the output protection circuit, and the source of the MOS tube is grounded; When the output protection circuit detects that the lithium battery pack is overcurrent or overvoltage, the output terminal of the output protection circuit outputs a high level to turn on the MOS tube, and the ground terminal of the fuse is grounded and turned on and blown to cut off the power to the external load; The output protection circuit includes a first output protection module and a second output protection module. The lithium battery pack includes a first lithium battery group and a second lithium battery group connected in series. The first lithium battery group and the second lithium battery group each include a plurality of lithium batteries. The positive output ends of all lithium batteries in the first lithium battery group are connected to the input end of the first output protection module. The positive output end of one of the lithium batteries in the first lithium battery group is also connected to the positive input end of an external load through a fuse. The positive output ends of all lithium batteries in the second lithium battery group are connected to the input end of the second output protection module. The positive output end of one of the lithium batteries in the second lithium battery group is also connected to the input end of the first output protection module. The negative output end of the second lithium battery group is also connected to the negative input end of the external load. The output end of the first output protection module and the output end of the second output protection module are both connected to the gate of the MOS tube. The first output protection module includes a first protection chip, a switch tube, a first triode, a second diode, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor and a fourteenth resistor. The first lithium battery group includes a first lithium battery, a second lithium battery and a third lithium battery connected in series. The positive output end of the first lithium battery is connected to the first detection end of the first protection chip through the first resistor, the positive output end of the second lithium battery is connected to the second detection end of the first protection chip through the second resistor, the positive output end of the third lithium battery is connected to the third detection end of the first protection chip through the third resistor, and the positive output end of the first lithium battery is connected to the power supply end of the first protection chip through the sixth resistor. The positive output end of the first lithium battery is connected to the base of the first triode through the sixth resistor and the seventh resistor in sequence, the base of the first triode is also connected to the drain of the switch tube through the fifth resistor, the positive output end of the first lithium battery is also connected to the positive input end of the external load through a fuse, the collector of the first triode is connected to the gate of the MOS tube through the fourteenth resistor, the output end of the first protection chip is connected to the gate of the switch tube through the fourth resistor, the source of the switch tube is connected to the ground end of the first protection chip and the output end of the second output protection module, and the output end of the second output protection module is also connected to the power input end of the first protection chip through the second diode; The second output protection module includes a second protection chip, and the output protection circuit also includes a third output protection module.

5. The lithium battery protection device as claimed in claim 4, It is characterized in that The second output protection module includes an eighth resistor, a ninth resistor, a tenth resistor, an eleventh resistor, a twelfth resistor, a thirteenth resistor, a third diode and a fourth diode. The second lithium battery group includes a fourth lithium battery, a fifth lithium battery, a sixth lithium battery and a seventh lithium battery connected in series. The positive output end of the fourth lithium battery is connected to the first detection end of the second protection chip through the eighth resistor, the positive output end of the fifth lithium battery is connected to the second detection end of the second protection chip through the ninth resistor, the positive output end of the sixth lithium battery is connected to the third detection end of the second protection chip through the tenth resistor, the positive output end of the seventh lithium battery is connected to the fourth detection end of the second protection chip through the eleventh resistor, the positive output end of the fourth lithium battery is also connected to the power input end of the second protection chip through the thirteenth resistor, the positive output end of the fourth lithium battery is also electrically connected to the source of the switch tube, the ground end of the second protection chip is grounded, the ground end of the second protection chip is also connected to the power input end of the second protection chip through the third diode, and the output end of the second protection chip is sequentially connected to the gate of the MOS tube through the twelfth resistor and the fourth diode.

6. The lithium battery protection device as claimed in claim 4, It is characterized in that The third output protection module includes an overcurrent and overvoltage detection chip, a fifteenth resistor, a sixteenth resistor, a seventeenth resistor, a first capacitor, a fifth diode, and a second transistor. The input end of the overcurrent and overvoltage detection chip is connected to the positive output end of the lithium battery pack, and the output end of the overcurrent and overvoltage detection chip is connected to the base of the second transistor through the fifteenth resistor, the first capacitor, the fifth diode, and the sixteenth resistor in sequence. The collector of the second transistor is connected to the base of the first transistor through the seventeenth resistor, and the base of the first transistor is also connected to the drain of the switch tube through the fifth resistor, and the emitter of the second transistor is grounded.

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