Battery charging protection circuit and charging earphone

Abstract

The application discloses a battery charging protection circuit and a charging earphone. The battery charging protection circuit comprises a charging control module, a first isolation module, a second isolation module and a third isolation module. The charging control module is used for charging the battery and outputting a charging signal when an external power supply is turned on. The first isolation module is used for obtaining the charging signal and isolating the battery from an electrical load. The second isolation module is used for obtaining the charging signal and outputting a conduction signal. The third isolation module is used for obtaining the conduction signal and turning on the charging control module and the electrical load. The first isolation module is used for isolating the battery from the electrical load when the battery is charging, thereby prolonging the service life of the battery and improving the safety. The second isolation module and the third isolation module are used for turning on the charging control module and the electrical load when the battery is charging, so that the external power supply supplies power to the electrical load, and the earphone can be normally used when charging.

Description

Technical Field

[0001] This application relates to the field of battery charging technology, and in particular to a battery charging protection circuit and a charging headset. Background Technology

[0002] In related technologies, the positive terminal of the headphone battery is usually directly connected to the electrical load. When using the headphones while charging, the battery will charge and discharge simultaneously, resulting in repeated charging and discharging. This can shorten battery life and may even cause the battery to explode. For safety reasons, some rechargeable headphones are designed not to work while charging, but this is inconvenient for users and affects the user experience. Summary of the Invention

[0003] This application aims to at least solve one of the technical problems existing in the prior art. To this end, this application proposes a battery charging protection circuit that disconnects the battery from the electrical load during battery charging through an isolation module, and allows an external power source to supply power to the electrical load, thereby protecting the battery without affecting the normal operation of the electrical load.

[0004] A battery charging protection circuit according to a first aspect embodiment of this application includes: a charging control module, which is used to charge the battery when an external power source is connected and output a charging signal; a first isolation module, which is connected to the charging control module and used to connect the battery, and is also used to acquire the charging signal and isolate the battery from the electrical load according to the charging signal; a second isolation module, which is connected to the charging control module and is used to acquire the charging signal and output a conduction signal according to the charging signal; and a third isolation module, which is connected to both the charging control module and the second isolation module, and is used to acquire the conduction signal and connect the charging control module to the electrical load according to the conduction signal.

[0005] The battery charging protection circuit according to the embodiments of this application has at least the following beneficial effects: the first isolation module isolates the battery from the electrical load during battery charging, avoiding simultaneous charging and discharging of the battery, thereby improving battery life and safety; the second and third isolation modules connect the charging control module to the electrical load during battery charging, enabling external power to supply power to the electrical load, thus allowing the electrical load to operate normally.

[0006] According to some embodiments of this application, it further includes: a voltage regulator module, which is connected to the charging control module and the third isolation module respectively. The voltage regulator module is used to acquire the charging signal and supply power to the electrical load according to the charging signal; the third isolation module is also used to connect the voltage regulator module and the electrical load according to the conduction signal.

[0007] According to some embodiments of this application, the first isolation module is further configured to connect the battery and the electrical load when the charging signal is not received.

[0008] According to some embodiments of this application, the first isolation module is further configured to output a cutoff signal when the charging signal is not received; the third isolation module is connected to the first isolation module, and the third isolation module is further configured to receive the cutoff signal and isolate the voltage regulator module from the power load according to the cutoff signal.

[0009] According to some embodiments of this application, the charging control module includes a charging control chip, which is connected to the battery, the first isolation module, the voltage regulator module and the second isolation module respectively.

[0010] According to some embodiments of this application, the first isolation module includes a first field-effect transistor (FET), a transient voltage suppressor (VT) diode, a first capacitor, a first resistor, and a second resistor; the drain of the first FET is connected to the battery, one end of the VT diode is connected to the drain of the first FET, and the other end of the VT diode is grounded, one end of the first capacitor is connected to the drain of the first FET, and the other end of the first capacitor is grounded, one end of the first resistor is connected to the gate of the first FET, and the other end of the first resistor is grounded, one end of the second resistor is connected to the gate of the first FET, and the other end of the second resistor is connected to the charging control chip, and the source of the first FET is connected to the electrical load.

[0011] According to some embodiments of this application, the second isolation module includes a second field-effect transistor, a third resistor, a fourth resistor, and a fifth resistor; the source of the second field-effect transistor is grounded, one end of the third resistor is connected to the gate of the second field-effect transistor, and the other end of the third resistor is grounded; one end of the fourth resistor is connected to the gate of the field-effect transistor, and the other end of the fourth resistor is connected to the charging control chip; one end of the fifth resistor is connected to the drain of the field-effect transistor, and the other end of the fifth resistor is connected to the third isolation module.

[0012] According to some embodiments of this application, the third isolation module includes a third field-effect transistor and a sixth resistor. The source of the third field-effect transistor is connected to the first isolation module and the electrical load. The gate of the third field-effect transistor is connected to the second isolation module. The drain of the third field-effect transistor is connected to the voltage regulator module. One end of the sixth resistor is connected to the source of the third field-effect transistor, and the other end of the sixth resistor is connected to the gate of the third field-effect transistor.

[0013] According to some embodiments of this application, the voltage regulator module includes a voltage regulator, a diode, a second capacitor, a third capacitor, a seventh resistor, an eighth resistor, a ninth resistor, a tenth resistor, and an eleventh resistor. The voltage regulator includes an input terminal, a ground terminal, an enable terminal, a setting terminal, and an output terminal. The anode of the diode is connected to the charging control chip, the cathode of the diode is connected to the input terminal, the ground terminal is grounded, one end of the second capacitor is connected to the input terminal, the other end of the second capacitor is grounded, one end of the third capacitor is connected to the output terminal, the other end of the third capacitor is grounded, one end of the seventh resistor is connected to the output terminal, the other end of the seventh resistor is connected to one end of the eighth resistor and the setting terminal, the other end of the eighth resistor is grounded, one end of the ninth resistor is connected to the input terminal, the other end of the ninth resistor is connected to one end of the tenth resistor and the enable terminal, the other end of the tenth resistor is grounded, one end of the eleventh resistor is connected to the input terminal, and the other end of the eleventh resistor is connected to the output terminal.

[0014] The charging earphones according to a second aspect embodiment of this application include the battery charging protection circuit described in the first aspect embodiment.

[0015] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0016] The present application will be further described below with reference to the accompanying drawings and embodiments, wherein:

[0017] Figure 1 This is a block diagram of one embodiment of the battery charging protection circuit of this application;

[0018] Figure 2 This is a block diagram of another embodiment of the battery charging protection circuit of this application;

[0019] Figure 3 This is a circuit diagram of one embodiment of the charging control module of this application;

[0020] Figure 4 for Figure 2 The circuit diagram shown is a circuit diagram of one embodiment of the battery charging protection circuit.

[0021] Figure label:

[0022] Charging control module 100, first isolation module 200, second isolation module 300, third isolation module 400, and voltage regulator module 500. Detailed Implementation

[0023] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0024] In the description of this application, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0025] In the description of this application, unless otherwise expressly defined, terms such as "setup," "installation," and "connection" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this application in conjunction with the specific content of the technical solution.

[0026] The battery charging protection circuit of this application embodiment can be applied to charging headphones. In existing lithium battery circuit designs, the positive terminal of the headphone battery is usually directly connected to the electrical load. When using headphones while charging, the battery will charge and discharge simultaneously, resulting in repeated charging and discharging. This can shorten battery life and may even cause the battery to explode, posing a certain safety hazard. Some manufacturers design headphones to not work while charging for safety reasons, but this causes inconvenience to users and affects the user experience.

[0027] Based on this, this application proposes a battery charging protection circuit and a charging earphone. By using an isolation module, the battery is disconnected from the electrical load during charging, and an external power source supplies power to the electrical load, thereby protecting the battery without affecting the normal operation of the electrical load.

[0028] Some embodiments, refer to Figure 1A battery charging protection circuit includes: a charging control module 100, a first isolation module 200, a second isolation module 300, and a third isolation module 400. The charging control module 100 is used to charge the battery when an external power source is connected and outputs a charging signal. The first isolation module 200 is connected to the charging control module 100 and is used to connect the battery. The first isolation module 200 is also used to acquire the charging signal and isolate the battery from the electrical load according to the charging signal. The second isolation module 300 is connected to the charging control module 100 and is used to acquire the charging signal and output a conduction signal according to the charging signal. The third isolation module 400 is connected to both the charging control module 100 and the second isolation module 300. The third isolation module 400 is used to acquire the conduction signal and connect the charging control module 100 to the electrical load according to the conduction signal.

[0029] It should be noted that in this embodiment, the external power source refers to AC mains power, and connecting to the external power source means connecting to AC mains power through a power adapter or other device. Therefore, the external power input voltage refers to the AC mains voltage after adjustment, typically 5V. The electrical load refers to all other circuitry of the headphones except for the battery charging protection circuit.

[0030] The charging control module 100 of this embodiment includes a power input terminal and a battery connection terminal. The power input terminal of the charging control module 100 is used to connect to an external power source, and its battery connection terminal is connected to a battery. After the external power source is turned on, the charging control module 100 charges the battery according to a predetermined charging mode. The charging signal is the high-level signal of the power input terminal of the charging control module 100. It is a high-level signal when the external power source is turned on and a low-level signal when the external power source is not turned on. Therefore, the charging signal is also equivalent to the voltage signal input from the external power source. The first isolation module 200 is connected to the power input terminal of the charging control module 100 and is connected to the battery and the electrical load respectively. When the external power source is turned on, the power input terminal of the charging control module 100 is at a high level. The first isolation module 200 receives the charging signal and isolates the battery and the electrical load, thus electrically disconnecting the battery from the electrical load.

[0031] The second isolation module 300 is connected to the power input terminal of the charging control module 100. When the external power is connected, it outputs a conduction signal.

[0032] The third control module is connected to the power input terminals of the second isolation module 300, the electrical load, and the charging control module 100. When the external power is connected, the third isolation module 400 connects the electrical load to the power input terminal of the charging control module 100 according to the conduction signal output by the second isolation module 300. This is equivalent to the electrical load being electrically connected to the external power supply, which then supplies power to the electrical load. This isolates and protects the battery without affecting the normal operation of other parts of the headphone circuitry, ensuring the headphone can be used normally while charging.

[0033] The battery charging protection circuit of this application embodiment has at least the following beneficial effects: the first isolation module 200 isolates the battery from the electrical load during battery charging, thereby avoiding the battery from charging and discharging at the same time, improving battery life and safety; the second isolation module 300 and the third isolation module 400 connect the charging control module 100 and the electrical load during battery charging, so that the external power supply supplies power to the electrical load, ensuring that the headphones can be used normally during charging.

[0034] Some embodiments, refer to Figure 2 The system also includes a voltage regulator module 500, which is connected to both the charging control module 100 and the third isolation module 400. The voltage regulator module 500 acquires a charging signal and supplies power to the electrical load based on the signal. The third isolation module 400 connects the voltage regulator module 500 to the electrical load based on a conduction signal. The voltage regulator module 500 regulates the input voltage and outputs a stable voltage. Different electrical load circuits require different operating voltages, and the external power input voltage may exceed the operating voltage of the electrical load. The external power input voltage is the AC mains voltage regulated by the power adapter, which has a certain standardized value and is not easily changed. Therefore, a voltage regulator module 500 is placed between the third isolation module 400 and the power input terminal of the charging control module 100 to further regulate the external power input voltage to meet the operating needs of the electrical load.

[0035] In some embodiments, the first isolation module 200 is also used to connect the battery and the electrical load when no charging signal is received. It is understood that when no external power source is connected and the battery is not charging, the battery needs to supply power to the electrical load; therefore, the first isolation module 200 connects the battery and the electrical load, establishing electrical conductivity between them.

[0036] In some embodiments, the first isolation module 200 is further configured to output a cutoff signal when no charging signal is received; the third isolation module 400 is connected to the first isolation module 200, and the third isolation module 400 is further configured to receive the cutoff signal and isolate the voltage regulator module 500 from the electrical load based on the cutoff signal. The voltage output terminal of the voltage regulator module 500 is connected to the electrical load through the third isolation module 400, and this connection terminal is a common terminal for connecting the voltage regulator module 500 and the electrical load. When no external power supply is connected, the first isolation module 200 connects the battery and the electrical load, and the battery supplies power to the electrical load. If the third isolation module 400 remains in the conducting state, that is, the voltage output terminal of the voltage regulator module 500 is connected to the electrical load, the battery voltage may flow back into the voltage regulator module 500 through the voltage output terminal of the voltage regulator module 500, causing damage to the components of the voltage regulator module 500. The first isolation module 200 outputs a cutoff signal, causing the third isolation module 400 to isolate the voltage regulator module 500 from the electrical load, thereby protecting the components of the voltage regulator module 500.

[0037] Some embodiments, refer to Figure 3 The charging control module 100 includes a charging control chip U1, which is connected to the battery, the first isolation module 200, the voltage regulator module 500, and the second isolation module 300. In an illustrative embodiment, the charging control chip U1 can be a SY6974 model charging management chip. Figure 3 As shown, pin 24 of the charging control chip U1 is the power input terminal (VBUS network terminal) of the charging control module 100, and pins 13 and 14 of the charging control module 100 are the charging terminals (VBAT network terminals) for charging the battery.

[0038] Some embodiments, refer to Figure 4 The first isolation module 200 includes a first field-effect transistor Q1, a transient suppression diode D1, a first capacitor C1, a first resistor R1, and a second resistor R2. The drain of the first field-effect transistor Q1 is used to connect to the battery. One end of the transient suppression diode D1 is connected to the drain of the first field-effect transistor Q1, and the other end of the transient suppression diode D1 is grounded. One end of the first capacitor C1 is connected to the drain of the first field-effect transistor Q1, and the other end of the first capacitor C1 is grounded. One end of the first resistor R1 is connected to the gate of the first field-effect transistor Q1, and the other end of the first resistor R1 is grounded. One end of the second resistor R2 is connected to the gate of the first field-effect transistor Q1, and the other end of the second resistor R2 is connected to the charging control chip U1. The source of the first field-effect transistor Q1 is used to connect to the electrical load. Figure 4The VCC network terminal is the endpoint for connecting the electrical load. The first field-effect transistor (FET), Q1, is a P-channel FET. When its gate is low, the source and drain are connected; when its gate is high, the source and drain are cut off. When an external power source is connected to charge the battery, VBUS is 5V (normally), the gate of FET Q1 is high, and FET Q1 is in the off state, disconnecting the battery from the electrical load. When no external power source is connected, VBUS is 0V, the gate of FET Q1 is low, and FET Q1 is in the on state, connecting the battery to the electrical load, which then supplies power to the load.

[0039] Some embodiments, refer to Figure 4 The second isolation module 300 includes a second field-effect transistor (FET) Q2, a third resistor R3, a fourth resistor R4, and a fifth resistor R5. The source of the second FET Q2 is grounded. One end of the third resistor R3 is connected to the gate of the second FET Q2, and the other end is grounded. One end of the fourth resistor R4 is connected to the gate of the FET, and the other end is connected to the charging control chip U1. One end of the fifth resistor R5 is connected to the drain of the FET, and the other end is connected to the third isolation module 400. The second FET Q2 is an N-channel FET. When its gate is low, its source and drain are cut off; when its gate is high, its source and drain are connected. When an external power supply is connected to charge the battery, VBUS is 5V, and the gate of the second FET Q2 is high. Therefore, the second FET Q2 operates in the on state, and its source and drain are connected. Because the source of the second field-effect transistor Q2 is grounded, its drain is also grounded, which is equivalent to outputting a low-level signal, which is the conduction signal.

[0040] Some embodiments, refer to Figure 4The third isolation module 400 includes a third field-effect transistor (FET) Q3 and a sixth resistor R6. The source of the third FET Q3 is connected to the first isolation module 200 and the electrical load, the gate of the third FET Q3 is connected to the second isolation module 300, and the drain of the third FET Q3 is connected to the voltage regulator module 500. One end of the sixth resistor R6 is connected to the source of the third FET Q3, and the other end of the sixth resistor R6 is connected to the gate of the third FET Q3. The third FET Q3 is a P-channel FET; when its gate is low, the source and drain are connected, and when its gate is high, the source and drain are cut off. When an external power supply is connected to charge the battery, the third FET Q3 receives a conduction signal from the second FET Q2, that is, the gate of the third FET Q3 is at the first level, and the third FET Q3 operates in the conducting state. The voltage output terminal of the voltage regulator module 500 is connected to the electrical load, and the external power supply voltage is further regulated by the voltage regulator module 500 to drive the electrical load. The gate of the third field-effect transistor Q3 is connected to the source of the first field-effect transistor Q1 through the sixth resistor R6. When no external power supply is connected to charge the battery, the first field-effect transistor Q1 is in the on state and the second field-effect transistor Q2 is in the off state. That is, the source and drain of the first field-effect transistor Q1 are regarded as a wire, and the source and drain of the second field-effect transistor Q2 are regarded as an open circuit.

[0041] The gate of the third field-effect transistor Q3 is connected to the battery via the sixth resistor R6. When its gate is in a high-level state, the third field-effect transistor Q3 is turned off, preventing the battery voltage from flowing into the voltage regulator module 500 from the voltage output terminal of the voltage regulator module 500.

[0042] Some embodiments, refer to Figure 4 The voltage regulator module 500 includes a voltage regulator U2, a diode D2, a second capacitor C2, a third capacitor C3, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, a tenth resistor R10, and an eleventh resistor R11. The voltage regulator U2 includes an input terminal, a ground terminal, an enable terminal, a setting terminal, and an output terminal. The positive terminal of the diode D2 is connected to the charging control chip U1, the negative terminal of the diode D2 is connected to the input terminal, and the ground terminal is grounded. One end of the second capacitor C2 is connected to the input terminal, and the other end of the second capacitor C2 is grounded. One end of the third capacitor C3 is connected to the output terminal, and the other end of the third capacitor C3 is grounded. One end of the seventh resistor R7 is connected to the output terminal, and the other end of the seventh resistor R7 is connected to one end of the eighth resistor R8 and the setting terminal. The other end of the eighth resistor R8 is grounded. One end of the ninth resistor R9 is connected to the input terminal, and the other end of the ninth resistor R9 is connected to one end of the tenth resistor R10 and the enable terminal. The other end of the tenth resistor R10 is grounded. One end of the eleventh resistor R11 is connected to the input terminal, and the other end of the eleventh resistor R11 is connected to the output terminal. In one embodiment, the voltage regulator U2 can be a CE6300 model linear voltage regulator U2. For example... Figure 4As shown, pin 1 of voltage regulator U2 is the input terminal, used to connect to an external power supply that requires voltage regulation; pin 2 of voltage regulator U2 is the ground terminal; pin 3 of voltage regulator U2 is the enable terminal, used to control voltage regulator U2 to enter the working state; pin 4 of voltage regulator U2 is the setting terminal, changing the resistance value connected to the setting terminal can change the output voltage of voltage regulator U2; pin 5 of voltage regulator U2 is the output terminal, used to output the regulated power supply voltage.

[0043] In some embodiments, the charging headphones include the battery charging protection circuit of any of the above embodiments.

[0044] In the description of this application, references to terms such as "one embodiment," "some embodiments," or "illustrative embodiment," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0045] The embodiments of this application have been described in detail above with reference to the accompanying drawings. However, this application is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of this application. Furthermore, unless otherwise specified, the embodiments and features described in the embodiments of this application can be combined with each other.

Claims

1. A battery charging protection circuit for charging headphones, characterized in that, include: A charging control module is used to charge the battery when an external power source is connected and to output a charging signal. A first isolation module is connected to the charging control module and is used to connect to the battery. The first isolation module is also used to acquire the charging signal and isolate the battery from the electrical load according to the charging signal. The second isolation module is connected to the charging control module. The second isolation module is used to acquire the charging signal and output a conduction signal according to the charging signal. The third isolation module is connected to the charging control module and the second isolation module respectively. The third isolation module is used to acquire the conduction signal and connect the charging control module and the electrical load according to the conduction signal. The third isolation module is also used to connect the electrical load and the power input terminal of the charging control module. The third isolation module connects the electrical load and the power input terminal of the charging control module according to the conduction signal output by the second isolation module, so that the external power supply supplies power to the electrical load. The first isolation module is also used to connect the third isolation module and to connect the electrical load.

2. The battery charging protection circuit according to claim 1, characterized in that, Also includes: A voltage regulator module is connected to the charging control module and the third isolation module respectively. The voltage regulator module is used to acquire the charging signal and supply power to the electrical load according to the charging signal. The third isolation module is also used to connect the voltage regulator module and the electrical load according to the conduction signal.

3. The battery charging protection circuit according to claim 1, characterized in that, The first isolation module is also used to connect the battery and the electrical load when the charging signal is not received.

4. The battery charging protection circuit according to claim 2, characterized in that, The first isolation module is also used to output a cutoff signal when the charging signal is not received; The third isolation module is connected to the first isolation module. The third isolation module is also used to acquire the cutoff signal and isolate the voltage regulator module from the power load according to the cutoff signal.

5. The battery charging protection circuit according to claim 2, characterized in that, The charging control module includes a charging control chip, which is connected to the battery, the first isolation module, the voltage regulator module, and the second isolation module.

6. The battery charging protection circuit according to claim 5, characterized in that, The first isolation module includes a first field-effect transistor, a transient suppression diode, a first capacitor, a first resistor, and a second resistor; The drain of the first field-effect transistor is used to connect to the battery. One end of the transient suppression diode is connected to the drain of the first field-effect transistor, and the other end of the transient suppression diode is grounded. One end of the first capacitor is connected to the drain of the first field-effect transistor, and the other end of the first capacitor is grounded. One end of the first resistor is connected to the gate of the first field-effect transistor, and the other end of the first resistor is grounded. One end of the second resistor is connected to the gate of the first field-effect transistor, and the other end of the second resistor is connected to the charging control chip. The source of the first field-effect transistor is used to connect to the electrical load.

7. The battery charging protection circuit according to claim 5, characterized in that, The second isolation module includes a second field-effect transistor, a third resistor, a fourth resistor, and a fifth resistor; The source of the second field-effect transistor is grounded. One end of the third resistor is connected to the gate of the second field-effect transistor, and the other end of the third resistor is grounded. One end of the fourth resistor is connected to the gate of the field-effect transistor, and the other end of the fourth resistor is connected to the charging control chip. One end of the fifth resistor is connected to the drain of the field-effect transistor, and the other end of the fifth resistor is connected to the third isolation module.

8. The battery charging protection circuit according to claim 5, characterized in that, The third isolation module includes a third field-effect transistor and a sixth resistor. The source of the third field-effect transistor is connected to the first isolation module and the electrical load. The gate of the third field-effect transistor is connected to the second isolation module. The drain of the third field-effect transistor is connected to the voltage regulator module. One end of the sixth resistor is connected to the source of the third field-effect transistor, and the other end of the sixth resistor is connected to the gate of the third field-effect transistor.

9. The battery charging protection circuit according to claim 5, characterized in that, The voltage regulator module includes a voltage regulator, a diode, a second capacitor, a third capacitor, a seventh resistor, an eighth resistor, a ninth resistor, a tenth resistor, and an eleventh resistor. The voltage regulator includes an input terminal, a ground terminal, an enable terminal, a setting terminal, and an output terminal. The positive terminal of the diode is connected to the charging control chip, the negative terminal of the diode is connected to the input terminal, the ground terminal is grounded, one end of the second capacitor is connected to the input terminal, the other end of the second capacitor is grounded, one end of the third capacitor is connected to the output terminal, the other end of the third capacitor is grounded, one end of the seventh resistor is connected to the output terminal, the other end of the seventh resistor is connected to one end of the eighth resistor and the setting terminal, the other end of the eighth resistor is grounded, one end of the ninth resistor is connected to the input terminal, the other end of the ninth resistor is connected to one end of the tenth resistor and the enable terminal, the other end of the tenth resistor is grounded, one end of the eleventh resistor is connected to the input terminal, and the other end of the eleventh resistor is connected to the output terminal.

10. A rechargeable earphone, characterized in that, Includes the battery charging protection circuit as described in any one of claims 1 to 9.

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