Earphone plugging detection circuit, earphone interface device and terminal equipment

Abstract

The embodiment of the invention provides an earphone plugging detection circuit, an earphone interface device and terminal equipment, and belongs to the technical field of electronic circuits. The circuit comprises a voltage bias unit, a plugging detection unit and an earphone microphone signal processing unit which are electrically connected with one another, the circuit provides stable bias voltage through the voltage bias unit, the plugging detection unit in the circuit judges the plugging state of an earphone by detecting voltage change and outputs a corresponding voltage signal to an ADC of a main chip, and the earphone microphone signal processing unit processes the earphone microphone signal. The circuit can quickly respond to the change of the plugging state of the earphone, improves the user experience, avoids the problems of mechanical wear and poor contact because a mechanical switch is not needed, can remarkably improve the reliability and service life of an earphone socket, and is simple and compact in circuit structure and convenient to use. And integration and realization are easy.

Description

Technical Field

[0001] The present invention relates to the field of electronic circuits, and in particular to an earphone plug-in detection circuit, an earphone interface device and a terminal device. Background Art

[0002] In terminal devices, headphones have become an important component that is widely used. Especially in mobile terminals, music players, computers and gaming devices, the use of headphones is becoming more and more common. With the continuous increase in user demand, how to efficiently and reliably detect the plug-in and unplug-out status of headphones has become an important design requirement. Traditional headphone plug-in detection usually relies on mechanical switches. Although this design is simple, it has many problems: the reliability of mechanical switches is low and they are prone to failure due to wear and poor contact; in addition, the use of mechanical switches increases the structural complexity and manufacturing cost of the headphone jack, and if the headphone socket does not have a mechanical switch, it is difficult to provide a reliable plug-in detection signal for the system chip (SOC) end. For this reason, it is necessary to provide a circuit or headphone socket that does not have a mechanical switch but can provide a stable and reliable headphone plug-in detection function to ensure accurate detection of the headphone plug-in status. Summary of the invention

[0003] In view of this, the embodiments of the present invention provide an earphone plug and unplug detection circuit, an earphone interface device and a terminal device, so as to solve the problem of low reliability of earphone plug and unplug detection without a mechanical switch in the prior art.

[0004] In a first aspect, an embodiment of the present invention provides a headphone plug and unplug detection circuit, the circuit comprising a voltage bias unit, a plug and unplug detection unit, and a headphone microphone signal processing unit electrically connected to each other, wherein the voltage bias unit is used to access a bias voltage source and provide a stable bias voltage for the plug and unplug detection unit and the headphone microphone signal processing unit, the headphone microphone signal processing unit is used to receive and process microphone signals and headphone button signals, the plug and unplug detection unit is used to output a corresponding voltage signal to the ADC of a main chip according to the plug and unplug status of the headphone, and the main chip determines whether the headphone is inserted according to the voltage signal.

[0005] Preferably, the voltage bias unit includes a third capacitor and a ninth resistor, wherein the third capacitor and the ninth resistor are electrically connected at a second node, the second node is connected to a bias voltage source, the other end of the third capacitor is grounded, and the other end of the ninth resistor is coupled to the plug-in detection unit and the headphone microphone signal processing unit at a first node.

[0006] Preferably, the plug-in detection unit includes a tenth resistor, an eleventh resistor, a twelfth resistor and a ninth capacitor, wherein one end of the eleventh resistor is a detection signal output end, and the other end is electrically connected to one end of the tenth resistor, the twelfth resistor and the ninth capacitor respectively, the other end of the tenth resistor is electrically connected to the first node, and the other ends of the ninth capacitor and the twelfth resistor are grounded.

[0007] Preferably, the headphone microphone signal processing unit includes a microphone signal processing subunit and a headphone button signal processing subunit, the positive signal and negative signal of the microphone are input to the main chip microphone interface via the microphone signal processing subunit, the headphone button signal is input to the main chip ADC via the headphone button processing subunit, and the headphone microphone signal processing unit is coupled to the plug-in detection unit and the voltage bias unit at the first node respectively.

[0008] Preferably, the headphone microphone signal processing subunit includes a fourth capacitor, a sixth capacitor, a fifth capacitor, a seventh capacitor and an eighth capacitor, one end of the fourth capacitor is electrically connected to the first node, and the other end is electrically connected to the microphone positive signal input terminal of the main chip, one end of the sixth capacitor is electrically connected to the first node via the fifth capacitor, and the other end is electrically connected to the microphone negative signal input terminal of the main chip, one end of the seventh capacitor is electrically connected between the sixth capacitor and the fifth capacitor, and the other end is grounded, and one end of the eighth capacitor is electrically connected to the first node, and the other end is grounded.

[0009] Preferably, the earphone button signal processing subunit comprises an eighth resistor, one end of the eighth resistor is electrically connected to the first node, and the other end of the eighth resistor is electrically connected to the ADC of the main chip.

[0010] Preferably, the voltage of the bias voltage source is 2V.

[0011] In a second aspect, an embodiment of the present invention provides a headphone interface device, comprising a headphone socket and a headphone plug and unplug detection circuit as described in any one of the first aspects, wherein the headphone socket comprises at least a headphone microphone signal input interface, a headphone audio feedback signal interface, a headphone right channel audio output interface, and a headphone left channel audio output interface, the headphone microphone signal input interface is electrically connected to a first node in the headphone plug and unplug detection circuit, and when a headphone is inserted into the headphone socket, the impedance in the headphone is electrically connected to the headphone plug and unplug detection circuit via the first node.

[0012] Preferably, the headphone interface device also includes a headphone interface protection circuit, wherein the headphone interface protection circuit includes a first ESD protection diode, a third ESD protection diode, a fourth ESD protection diode, a first capacitor, a second capacitor, a seventh resistor and a sixth resistor, wherein the first ESD protection diode, the second capacitor in series and the sixth resistor are electrically connected between the headphone left channel audio output interface and the ground, the third ESD protection diode, the first capacitor in series and the seventh resistor are electrically connected between the headphone right channel audio output interface and the ground, and the fourth ESD protection diode is electrically connected between the headphone microphone signal input interface and the ground.

[0013] In a third aspect, an embodiment of the present invention provides a terminal device, comprising an ADC main chip, and an earphone plug detection circuit as described in any one of the first aspect or an earphone interface device as described in the second aspect.

[0014] In summary, the beneficial effects of the present invention are as follows:

[0015] The embodiment of the present invention provides a headphone plug-in detection circuit, a headphone interface device and a terminal device, wherein the circuit includes a voltage bias unit, a plug-in detection unit and a headphone microphone signal processing unit which are electrically connected to each other, and the circuit provides a stable bias voltage through the voltage bias unit. The plug-in detection unit in the circuit determines the plug-in state of the headphone by detecting the voltage change, and outputs the corresponding voltage signal to the ADC of the main chip, thereby realizing accurate detection of the plug-in of the headphone. The circuit can quickly respond to the change of the plug-in state of the headphone, thereby improving the user experience, because there is no need to use a mechanical switch, thereby avoiding the problems of mechanical wear and poor contact, and significantly improving the reliability and service life of the headphone socket. In addition, the headphone microphone signal processing unit can not only receive and process microphone signals, but also process headphone button signals, thereby realizing multi-functional integration. Through the stable power supply of the voltage bias unit, the microphone signal processing unit can accurately process audio signals and button signals under stable working conditions, thereby ensuring the accuracy and consistency of signal processing. Overall, the circuit structure is simple and compact, easy to integrate and implement, and can work stably in a complex electromagnetic environment, thereby providing an efficient and reliable plug-in detection solution for the headphone interface in the terminal device. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solution of the embodiment of the present invention, the drawings required for use in the embodiment of the present invention will be briefly introduced below. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work, and these are all within the protection scope of the present invention.

[0017] Figure 1It is a schematic diagram of the structure of a headphone plug-in detection circuit according to an embodiment of the present invention.

[0018] Figure 2 Detailed circuit diagram of the headphone plug detection circuit according to the embodiment of the present invention.

[0019] Figure 3 Detailed circuit diagram of the headphone plug detection circuit according to the embodiment of the present invention.

[0020] Figure 4 4 is a circuit diagram of an earphone socket according to an embodiment of the present invention.

[0021] Figure 5 It is a schematic diagram of the connection between the main chip and the headphone interface device / headphone plug detection circuit according to an embodiment of the present invention. DETAILED DESCRIPTION

[0022] The features and exemplary embodiments of various aspects of the present invention will be described in detail below. In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and Examples. It should be understood that the specific embodiments described herein are only configured to explain the present invention and are not configured to limit the present invention. For those skilled in the art, the present invention can be implemented without the need for some of these specific details. The following description of the embodiments is only to provide a better understanding of the present invention by illustrating examples of the present invention.

[0023] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. Moreover, the term "include", "comprise" or any other variant thereof is intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or equipment. In the absence of more restrictions, the elements defined by the sentence "include..." do not exclude the existence of other identical elements in the process, method, article or equipment including the elements. The implementation method described below is only schematic, and the division of the module or circuit is only a logical function division, and there may be other division methods when actually implemented. In this embodiment and the accompanying drawings, elements unrelated to the present invention have been omitted and not illustrated, and the size relationship between the elements in the accompanying drawings is only for easy understanding, not for limiting the actual proportion.

[0024] See also Figure 1An embodiment of the present invention provides an earphone plug-in detection circuit 50, wherein the circuit 50 includes a voltage bias unit 51, a plug-in detection unit 52, and an earphone microphone signal processing unit 53 which are electrically connected to each other, wherein the voltage bias unit 51 is used to access a bias voltage source and provide a stable bias voltage for other units in the circuit, the earphone microphone signal processing unit 53 is used to receive and process microphone signals and earphone button signals, and output the processed microphone signals and earphone button signals to the ADC of the main chip 40, and the plug-in detection module is used to output a corresponding voltage signal to the ADC of the main chip (SOC) 40 according to the plug-in status of the earphone to determine whether the earphone is inserted. Specifically, the voltage bias unit 51, the plug-in detection unit 52, and the headphone microphone signal processing unit 53 are coupled to the first node 10. The first node is the headphone microphone insertion detection node. When the headphone is inserted into the headphone socket, the impedance of the headphone itself is connected to the headphone insertion detection circuit from the first node. After the bias voltage at the first node is divided by the headphone impedance, the voltage signal LRADC1 output from the detection signal output end of the plug-in detection unit will be smaller than the output voltage signal when the headphone is not connected. Therefore, a preset voltage threshold can be set according to the impedance of the plug-in detection unit and the headphone impedance. The ADC in the main chip samples the voltage signal LRADC1 output from the detection signal output end, and determines whether the voltage signal is greater than or less than the preset voltage threshold to determine whether the headphone is plugged in or out.

[0025] Figure 2 is a specific circuit diagram of the headphone plug-in detection circuit. In one embodiment, the voltage bias unit 51 includes a bias capacitor and a bias resistor, namely a third capacitor C3 and a ninth resistor R9, the third capacitor C3 and the ninth resistor R9 are electrically connected at the second node 20, the second node 20 is connected to the bias voltage source HBIAS, the other end of the third capacitor C3 is grounded, and the other end of the ninth resistor R9 is coupled to the plug-in detection unit 52 and the headphone microphone signal processing unit 53 at the first node 10. The bias voltage source HBIAS can provide a stable DC bias voltage after passing through the third capacitor C3 and the ninth resistor of the voltage bias unit.

[0026] In one embodiment, the plug-in detection unit includes a tenth resistor R10, an eleventh resistor R11, a twelfth resistor R12 and a ninth capacitor C9, wherein one end of the eleventh resistor R11 is a detection signal output terminal A, and the other end is electrically connected to one end of the tenth resistor R10, the twelfth resistor R12 and the ninth capacitor C9 respectively, the other end of the tenth resistor R10 is electrically connected to the first node 10, and the other ends of the ninth capacitor C9 and the twelfth resistor R12 are grounded. By collecting the voltage change of the voltage signal LRADC1 of the detection signal output terminal A, it can be determined whether the earphone is inserted. Preferably, as Figure 3As shown: HBIAS = 2V, R10 = 51KΩ, R12 = 100KΩ, when the earphone is not inserted, the voltage in the circuit forms a voltage divider through the tenth resistor R10 and the twelfth resistor R12, and the detection signal input terminal voltage signal LRADC1 is about 1.36V (error ± 0.05V). When the earphone is inserted, the bias voltage of the first node is divided by the resistor or impedance in the earphone, and the detection signal input terminal voltage signal LRADC1 is about 1.0V (error ± 0.05V). Then a preset voltage threshold can be set. For example, the preset voltage threshold is 1.2V. When the ADC of the main chip collects the voltage at the output terminal of the detection signal greater than 1.2V, it is considered that the earphone is not inserted, and the earphone output (HPOUT) is turned off; when the ADC of the main chip collects the voltage at the output terminal of the detection signal less than 1.2V, it is considered that the earphone is inserted, and the earphone output is turned on.

[0027] In one embodiment, the headphone microphone signal processing unit 53 includes a microphone signal processing subunit 31 and a headphone button signal processing subunit 32. The microphone positive signal (HS-MIC) and negative signal (MIC2N-N) are input to the microphone interface of the main chip (receiving MICIN3P and MICIN3N signals) via the microphone signal processing subunit. The headphone button signal MIC-DEC is input to the main chip ADC via the headphone button processing subunit. The headphone microphone signal processing unit 53 is coupled to the plug-in detection unit 52 and the voltage bias unit 51 at the first node respectively.

[0028] like Figure 2 As shown in Figure 3, the headphone microphone signal processing subunit includes a fourth capacitor C4, a sixth capacitor C6, a fifth capacitor C5, a seventh capacitor C7 and an eighth capacitor C8, one end of the fourth capacitor C4 is electrically connected to the first node 10, and the other end is electrically connected to the microphone positive signal input end of the main chip (receiving MICIN3P signal), one end of the sixth capacitor C6 is electrically connected to the first node 10 through the fifth capacitor C5, and the other end is electrically connected to the microphone negative signal input end of the main chip (receiving MICIN3N signal), one end of the seventh capacitor C7 is electrically connected between the sixth capacitor C6 and the fifth capacitor C5, and the other end is grounded, and one end of the eighth capacitor C8 is electrically connected to the first node 10, and the other end is grounded. Capacitors C4, C5, C6, C7, and C8 are used for signal coupling and filtering to ensure the purity of the microphone input signal. The headphone button signal processing subunit includes an eighth resistor R8, one end of the eighth resistor R8 is electrically connected to the first node 10, and the other end is electrically connected to the ADC of the main chip, and the received headphone button signal (MIC-DET) such as the volume up and down key signal is input into the ADC of the main chip.

[0029] In summary, the earphone plug-in detection circuit of the embodiment of the present invention includes a voltage bias unit, a plug-in detection unit, and an earphone microphone signal processing unit electrically connected to each other. The circuit provides a stable bias voltage through the voltage bias unit. The plug-in detection unit in the circuit determines the plug-in state of the earphone by detecting the voltage change, and outputs the corresponding voltage signal to the ADC of the main chip, thereby realizing accurate detection of earphone plug-in. The circuit can quickly respond to the change of the earphone plug-in state, improve the user experience, because there is no need to use a mechanical switch, thereby avoiding the problems of mechanical wear and poor contact, and can significantly improve the reliability and service life of the earphone socket. In addition, the earphone microphone signal processing unit can not only receive and process microphone signals, but also process earphone button signals, thereby realizing multi-functional integration. Through the stable power supply of the voltage bias unit, the microphone signal processing unit can accurately process audio signals and button signals under stable working conditions, ensuring the accuracy and consistency of signal processing. Overall, the circuit structure is simple and compact, easy to integrate and implement, and can work stably in a complex electromagnetic environment, providing an efficient and reliable plug-in detection solution for the earphone interface in the terminal device.

[0030] Embodiment 2

[0031] An embodiment of the present invention provides an earphone interface device, the earphone interface device comprising an earphone socket and an earphone plug-in detection circuit as described in Embodiment 1. Figure 4 As shown, the headphone socket at least includes a headphone microphone signal input interface 1 (receiving HS-MIC-1 signal from the headphone), a headphone audio feedback signal interface 5 (HPOUTFB-1), a headphone right channel audio output interface 2 (outputting HPOUTR signal), and a headphone left channel audio output interface 3 (outputting HPOUTL signal). The headphone microphone signal input interface 1 is electrically connected to the first node 10 in the headphone plug-in detection circuit. When a headphone is inserted into the headphone socket, the impedance in the headphone is electrically connected to the headphone plug-in detection circuit via the first node 10, and the voltage signal output by the plug-in detection unit in the headphone plug-in detection circuit changes (becomes smaller). The main chip ADC collects the voltage signal and determines that the headphone is inserted. When a headphone is inserted into the headphone socket, the first node 10 is not connected to the headphone impedance, and the voltage signal output by the plug-in detection unit in the headphone plug-in detection circuit changes (becomes larger). The main chip ADC collects the voltage signal and determines that the headphone is unplugged.

[0032] like Figure 4As shown, the headphone interface device also includes a headphone interface protection circuit, wherein the headphone interface protection circuit includes a first ESD protection diode ED1, a third ESD protection diode ED3, a fourth ESD protection diode ED4, a first capacitor C1, a second capacitor C2, a seventh resistor R7 and a sixth resistor R6, wherein the first ESD protection diode ED1 is electrically connected between the left channel audio output interface of the headphone and the ground to protect the left channel audio output line, the second capacitor C2 and the sixth resistor C6 connected in series are electrically connected between the left channel audio output interface of the headphone and the ground to limit the current and high-frequency filtering of the left channel output signal, the third ESD protection diode ED3 is electrically connected between the right channel audio output interface of the headphone and the ground to protect the left channel audio output line, the first capacitor C1 and the seventh resistor R7 connected in series are electrically connected between the right channel audio output interface of the headphone and the ground to limit the current and high-frequency filtering of the right channel output signal, and the fourth ESD protection diode ED4 is electrically connected between the microphone signal input interface of the headphone and the ground to protect the left channel audio output line for current limiting and high-frequency filtering of the microphone signal. In addition, as Figure 4 As shown, a second resistor R2 and a fourth resistor R4 are connected between the corresponding interfaces of the headphone left channel audio output interface and the headphone right channel audio output interface main chip of the headphone jack, and a design compatible with the national standard and the American standard can be achieved by setting the values ​​of R2 and R4.

[0033] The headphone interface device integrates a headphone plug-in detection circuit and a headphone interface protection circuit, wherein the headphone plug-in detection circuit can accurately determine the insertion status of the headphone, and the design without mechanical switches reduces the risk of mechanical wear and poor contact, significantly improving the reliability and service life of the system; in addition, the headphone interface protection circuit adopts a combination of ESD protection diodes, capacitors and resistors, providing comprehensive electrostatic protection and signal filtering. Specifically, the first and third ESD protection diodes are respectively connected between the left and right channel audio output interfaces of the headphone and the ground, which can effectively prevent electrostatic discharge from damaging the circuit. The fourth ESD protection diode is connected between the headphone microphone signal input interface and the ground, further enhancing the electrostatic protection effect. The capacitors and resistors connected in series are used to filter out high-frequency noise and interference to ensure the purity and stability of the audio signal.

[0034] In summary, the headphone interface device not only realizes reliable headphone plug-in detection and signal processing, but also greatly improves the anti-interference ability and safety of the system. The circuit structure is simple and compact, easy to integrate, and can work stably in complex electromagnetic environments, making the headphone interface device have a wide range of application prospects in terminal devices, improving user experience and the overall performance of the device.

[0035] Embodiment 3

[0036] An embodiment of the present invention provides a terminal device, such as Figure 5As shown, the terminal device includes a main chip and the earphone plug detection circuit as described in the first embodiment or the earphone interface device as described in the second embodiment. The main chip can be an ARMSOC, FPGA, DSP device, such as Figure 5 As shown, the voltage signal LRADC1 output from the headphone jack or the headphone plug-in detection circuit is input into the ADC of the main chip, the headphone button signal MIC-DET is also input into the ADC of the main chip, and the audio input related signals (such as MICIN3P, MICIN3N) are input into the corresponding microphone interface (MIC interface) of the main chip. The audio signals such as the left channel signal HPOUTR and the right audio signal HPOUTL are output to the headphone jack through the corresponding audio output interface.

[0037] The electronic device integrates the ADC main chip and the headphone plug-in detection circuit or headphone interface device to achieve accurate headphone plug-in status detection and automatic audio output control. The headphone plug-in status is detected by voltage changes, and the ESD protection diode and filter capacitor are used to ensure signal purity and system stability, which can significantly improve the reliability and service life of the terminal equipment and enhance the user experience.

[0038] The headphone plug-in detection provided by the present invention is described in detail above. Those skilled in the art will further understand that the various illustrative logic blocks, modules, circuits and algorithm steps described in conjunction with the embodiments disclosed herein can be implemented as electronic hardware, computer software or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, various illustrative components, blocks, modules, circuits and steps have been described above in general terms of functionality. Whether the functionality is implemented as hardware or software depends on the specific use and the design constraints imposed on the entire system. Those skilled in the art can implement the described functionality in different ways for each specific use. Any equivalent structure or equivalent process transformation made using the contents of the specification and drawings of the present invention, or directly or indirectly used in other related technical fields, are similarly included in the patent protection scope of the present invention. It should not be understood as a limitation of the present invention.

[0039] The above is only a specific implementation of the present invention. Those skilled in the art can clearly understand that for the convenience and simplicity of description, the specific working process of the system, module and unit described above can refer to the corresponding process in the aforementioned method embodiment, and will not be repeated here. It should be understood that the protection scope of the present invention is not limited to this. 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 covered within the protection scope of the present invention.

Claims

1. A headphone plug-in detection circuit, characterized in that: The circuit includes a voltage bias unit, a plug-in detection unit, and an earphone microphone signal processing unit that are electrically connected to each other, wherein the voltage bias unit is used to access a bias voltage source and provide a stable bias voltage for the plug-in detection unit and the earphone microphone signal processing unit, the earphone microphone signal processing unit is used to receive and process microphone signals and earphone button signals, the plug-in detection unit is used to output corresponding voltage signals to the ADC of the main chip according to the plug-in status of the earphone, and the main chip determines whether the earphone is inserted according to the voltage signal.

2. The headphone plug detection circuit according to claim 1, characterized in that: The voltage bias unit includes a third capacitor and a ninth resistor, wherein the third capacitor and the ninth resistor are electrically connected at a second node, the second node is connected to a bias voltage source, the other end of the third capacitor is grounded, and the other end of the ninth resistor is coupled to the plug-in detection unit and the headphone microphone signal processing unit at a first node.

3. The headphone plug detection circuit according to claim 1, characterized in that: The plug-in detection unit includes a tenth resistor, an eleventh resistor, a twelfth resistor and a ninth capacitor, wherein one end of the eleventh resistor is a detection signal output end, and the other end is electrically connected to one end of the tenth resistor, the twelfth resistor and the ninth capacitor respectively, the other end of the tenth resistor is electrically connected to the first node, and the other ends of the ninth capacitor and the twelfth resistor are grounded.

4. The headphone plug detection circuit according to claim 1, characterized in that: The headphone microphone signal processing unit includes a microphone signal processing subunit and a headphone button signal processing subunit. The positive signal and negative signal of the microphone are input to the main chip microphone interface via the microphone signal processing subunit, and the headphone button signal is input to the main chip ADC via the headphone button processing subunit. The headphone microphone signal processing unit is coupled to the plug-in detection unit and the voltage bias unit at the first node respectively.

5. The headphone plug-in detection circuit according to claim 4, characterized in that: The headphone microphone signal processing subunit includes a fourth capacitor, a sixth capacitor, a fifth capacitor, a seventh capacitor and an eighth capacitor, one end of the fourth capacitor is electrically connected to the first node, and the other end is electrically connected to the microphone positive signal input terminal of the main chip, one end of the sixth capacitor is electrically connected to the first node via the fifth capacitor, and the other end is electrically connected to the microphone negative signal input terminal of the main chip, one end of the seventh capacitor is electrically connected between the sixth capacitor and the fifth capacitor, and the other end is grounded, and one end of the eighth capacitor is electrically connected to the first node, and the other end is grounded.

6. The headphone plug-in detection circuit according to claim 4, characterized in that: The earphone button signal processing subunit includes an eighth resistor, one end of the eighth resistor is electrically connected to the first node, and the other end of the eighth resistor is electrically connected to the ADC of the main chip.

7. The headphone plug detection circuit according to any one of claims 1 to 6, characterized in that: The voltage of the bias voltage source is 2V.

8. A headphone interface device, comprising a headphone socket and a headphone plug-in detection circuit as described in any one of claims 1 to 6, wherein the headphone socket at least comprises a headphone microphone signal input interface, a headphone audio feedback signal interface, a headphone right channel audio output interface, and a headphone left channel audio output interface, the headphone microphone signal input interface is electrically connected to a first node in the headphone plug-in detection circuit, and when a headphone is inserted into the headphone socket, the impedance in the headphone is electrically connected to the headphone plug-in detection circuit via the first node.

9. The headphone interface device according to claim 8, characterized in that: The headphone interface device also includes a headphone interface protection circuit, wherein the headphone interface protection circuit includes a first ESD protection diode, a third ESD protection diode, a fourth ESD protection diode, a first capacitor, a second capacitor, a seventh resistor and a sixth resistor, wherein the first ESD protection diode, the second capacitor in series and the sixth resistor are electrically connected between the headphone left channel audio output interface and the ground, the third ESD protection diode, the first capacitor in series and the seventh resistor are electrically connected between the headphone right channel audio output interface and the ground, and the fourth ESD protection diode is electrically connected between the headphone microphone signal input interface and the ground.

10. A terminal device, characterized in that: The terminal device comprises an ADC main chip, and the headphone plug detection circuit according to any one of claims 1 to 7 or the headphone interface device according to claim 8 or 9.

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