Audio protection circuit, in-vehicle audio system, and vehicle

Abstract

This invention relates to the field of circuit technology and discloses an audio protection circuit, an in-vehicle audio system, and a vehicle. In this audio protection circuit, an audio processing circuit processes the input audio signal. A first terminal of an audio output circuit is coupled to the first terminal of the audio processing circuit via a first branch, and a second terminal of the audio output circuit is coupled to the second terminal of the audio processing circuit via a second branch, for outputting the processed audio signal. A first protection circuit is coupled between the first and second terminals of the audio processing circuit and, when the voltage on the first branch and / or the second branch exceeds a first voltage threshold, discharges the voltage on the first branch and / or the second branch. Applying the technical solution of this invention can improve the transmission quality of audio signals.

Description

Technical Field

[0001] This invention relates to the field of circuit technology, specifically to audio protection circuits, in-vehicle audio systems, and vehicles. Background Technology

[0002] Audio processing circuits are typically precision semiconductor integrated circuits. If there is overvoltage on the transmission line between the audio processing circuit and the output terminal, it will damage the audio processing circuit. Therefore, an overvoltage protection circuit is required to prevent damage to the audio processing circuit from overvoltage signals.

[0003] In related technologies, the voltage on the transmission line is collected, and software is used to determine whether the voltage is abnormal. If an abnormality is found, a switch set on the transmission line is opened to disconnect the audio processing circuit, thereby protecting the audio processing circuit.

[0004] However, in related technologies, overvoltage faults of varying degrees are protected by disconnecting the audio processing circuit. Frequent switching interrupts the audio signal, causing it to distort. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this application is to provide an audio protection circuit, an in-vehicle audio system and a vehicle, which aims to solve the technical problem of audio signal distortion caused by frequent switching on and off in the prior art.

[0006] In a first aspect, embodiments of this application provide an audio protection circuit, including: an audio processing circuit, an audio output circuit, and a first protection circuit. The audio processing circuit is used to process an input audio signal. A first terminal of the audio output circuit is coupled to the first terminal of the audio processing circuit through a first branch, and a second terminal of the audio output circuit is coupled to the second terminal of the audio processing circuit through a second branch, for outputting the processed audio signal. The first protection circuit is coupled between the first terminal and the second terminal of the audio processing circuit, and is used to discharge the voltage on the first branch and / or the second branch when the voltage on the first branch and / or the second branch is greater than a first voltage threshold.

[0007] In this embodiment, a first protection circuit is coupled between the first and second terminals of the audio processing circuit. When the voltage on any branch exceeds a first voltage threshold, the first protection circuit directly discharges the overvoltage, quickly suppressing the branch overvoltage and preventing damage to the audio processing circuit. Based on the first protection circuit provided in this application, frequent switching is unnecessary, avoiding audio signal interruptions and distortion caused by switching actions. This ensures the continuity and stability of the audio signal output and improves audio transmission quality.

[0008] In one possible embodiment, the first protection circuit includes: a first diode, a second diode, and a first Zener diode. The anode of the first diode is coupled to a first terminal of the audio processing circuit, the anode of the second diode is coupled to a second terminal of the audio processing circuit, the cathode of the second diode is coupled to the cathode of the first diode, the anode of the first Zener diode is used to couple to a voltage reference terminal, the cathode of the first Zener diode is coupled to the cathode of the second diode, and the cathode of the first Zener diode is also used to couple to a power supply circuit.

[0009] In this embodiment, the first protection circuit comprises a passive protection structure consisting of a diode and a Zener diode. The first diode provides unidirectional conduction for overvoltage in the first branch, and the second diode provides unidirectional conduction for overvoltage in the second branch. The first Zener diode precisely matches the first voltage threshold through its reverse breakdown threshold; during overvoltage, reverse breakdown forms a discharge circuit, which can quickly suppress branch overvoltage. Simultaneously, the clamping characteristic of the first Zener diode stabilizes the voltage during the discharge process, preventing voltage fluctuations from affecting the audio signal. Therefore, frequent on / off control is unnecessary, eliminating the interference of switching actions on the audio signal at the hardware level and ensuring the stability of the audio output.

[0010] In one possible embodiment, when the voltage on the first branch and / or the second branch is greater than the first voltage threshold, the first Zener diode conducts from the cathode to the anode of the first Zener diode to discharge the voltage on the first branch and / or the second branch, thereby stabilizing the voltage on the first branch and / or the second branch at the first voltage threshold.

[0011] In conjunction with the above embodiments, when the voltage on the first branch and / or the second branch exceeds the first voltage threshold, the first Zener diode is reverse-broken down and conducts along its cathode to anode direction, forming an overvoltage discharge circuit at both ends of the audio processing circuit. The overvoltage of the first branch and / or the second branch is quickly discharged through this circuit. At the same time, relying on the reverse breakdown clamping characteristic of the first Zener diode, the voltage on the first branch and / or the second branch is accurately stabilized at the first voltage threshold. This achieves overvoltage protection, avoids sudden voltage changes from interfering with the audio signal, and ensures continuous and stable audio output without switching on or off.

[0012] In one possible embodiment, the audio protection circuit further includes: a second protection circuit coupled between the audio processing circuit and the audio output circuit, used to control the first branch and / or the second branch to disconnect when the voltage on the first branch and / or the second branch is greater than a second voltage threshold, wherein the second voltage threshold is greater than the first voltage threshold.

[0013] In this embodiment, a second protection circuit is added to the audio protection circuit, employing a two-stage protection logic. The second voltage threshold is higher than the first voltage threshold. Under normal conditions, the first protection circuit clamps and discharges small overvoltages through the first Zener diode, without branch switching, thus avoiding signal interference and ensuring stable audio output. When the voltage of the first branch and / or the second branch exceeds the higher second voltage threshold, the second protection circuit is triggered and cuts off the corresponding branch, achieving hardware protection against large overvoltages and preventing damage to the audio processing circuit due to overvoltage. This two-stage protection ensures stable audio output under normal operating conditions through passive discharge and addresses extreme overvoltages through circuit breaking protection, balancing audio performance and circuit safety. Furthermore, it eliminates the need for frequent switching, further maintaining output continuity.

[0014] In one possible embodiment, the second protection circuit includes: a first switching device, a second switching device, and a switching circuit. The first switching device is disposed on a first branch and configured to disconnect when the voltage signal received at the controlled terminal of the first switching device is less than the cutoff voltage. The second switching device is disposed on a second branch and configured to disconnect when the voltage signal received at the controlled terminal of the second switching device is less than the cutoff voltage. A first terminal of the switching circuit is coupled to the first branch, a second terminal of the switching circuit is coupled to the second branch, a third terminal of the switching circuit is coupled to the controlled terminals of the first and second switching devices, and a fourth terminal of the switching circuit is coupled to a voltage reference terminal and configured to conduct between the third and fourth terminals of the switching circuit when the voltage value at the first and / or second terminals of the switching circuit is greater than a second voltage threshold.

[0015] In this embodiment, the second protection circuit employs switching devices (including a first switching device and a second switching device) and a switching circuit to form a two-stage overvoltage protection. The first and second switching devices are connected in series in the first and second branches, respectively. When the branch voltage exceeds a second voltage threshold, the third and fourth terminals of the switching circuit are turned on, causing the voltage at the controlled terminal of the switching device to drop below the cutoff voltage, triggering the corresponding branch switching device to disconnect, thus achieving circuit breaking protection against extreme overvoltage. Based on the second protection circuit, branch switching is only triggered under extreme operating conditions, avoiding damage to the circuit from extreme overvoltage and improving the safety performance of the audio protection circuit.

[0016] In one possible embodiment, the switching circuit further includes a detection circuit and a third switching device. A first terminal of the detection circuit is coupled to a first branch, and a second terminal of the detection circuit is coupled to a second branch. The detection circuit is configured such that when the voltage value at the first terminal of the detection circuit is greater than a second voltage threshold, the first terminal and the third terminal are connected; and when the voltage value at the second terminal of the detection circuit is greater than the second voltage threshold, the second terminal and the third terminal are connected. A first terminal of the third switching device is coupled to a third terminal of the detection circuit, and a second terminal of the third switching device is coupled to the controlled terminals of the first and second switching devices. The third terminal of the third switching device is used to couple to a voltage reference terminal and is configured such that when the voltage between the first terminal and the third terminal of the third switching device is greater than the conduction voltage, the second terminal and the third terminal of the third switching device are connected.

[0017] In this embodiment, the second protection circuit forms an overvoltage detection and switch triggering linkage logic with the third switching device through a detection circuit. The detection circuit detects the voltage of the two branches respectively. When the voltage of either branch is greater than the second voltage threshold, the corresponding detection terminal and the third terminal are connected. The third switching device is driven by the output of the detection circuit. When the voltage between the first and third terminals of the third switching device is greater than the conduction voltage, the second and third terminals are connected, pulling the controlled terminals of the first and second switching devices to the voltage reference terminal, causing the branch switching device to disconnect because the controlled terminal voltage is less than the cutoff voltage. In this embodiment, by using hardware logic to trigger the branch connection and disconnection when the voltage is greater than the second voltage threshold, it is possible to ensure that the branch protection audio processing circuit is disconnected even under extreme overvoltage conditions, thereby improving the safety performance of the audio protection circuit.

[0018] In one possible embodiment, the detection circuit includes: a second Zener diode, a first resistor, a third Zener diode, and a second resistor. The cathode of the second Zener diode is coupled to a first branch, the anode of the second Zener diode is coupled to a first terminal of the first resistor, the second terminal of the first resistor is coupled to a first terminal of a third switching device, the cathode of the third Zener diode is coupled to a second branch, the anode of the third Zener diode is coupled to a first terminal of the second resistor, and the second terminal of the second resistor is coupled to a first terminal of the third switching device.

[0019] In this embodiment, a passive overvoltage detection unit is constructed using Zener diodes and resistors. The cathodes of the second and third Zener diodes are connected to the first and second branches, respectively, while their anodes are connected to the first terminal of the third switching device via corresponding resistors. The reverse breakdown voltage of the Zener diodes matches a second voltage threshold. When the voltage of any branch exceeds the second threshold, the corresponding Zener diode reverse-breaks and conducts, inputting voltage to the first terminal of the third switching device via the resistor. This causes the voltage between the three terminals to reach the conduction threshold, thereby lowering the controlled terminal voltage of the branch switching devices (including the first and second switching devices) to disconnect the branch. This detection circuit is a passive structure with no active control losses, and only extreme overvoltage triggers switching on and off. Under normal operating conditions, the first protection circuit discharges overvoltage, avoiding frequent switching actions, preventing signal interference, and ensuring stable audio output. Simultaneously, the two-stage protection accurately adapts to different overvoltage scenarios, balancing circuit protection reliability and audio output performance.

[0020] In one possible embodiment, the audio protection circuit further includes a voltage regulator circuit, which includes a fourth Zener diode, a third resistor, and a fourth resistor. The cathode of the fourth Zener diode is coupled to the controlled terminal of the first switching device and the controlled terminal of the second switching device. The anode of the fourth Zener diode is used to couple to a voltage reference terminal. The first terminal of the third resistor is coupled to the controlled terminal of the first switching device and the controlled terminal of the second switching device. The second terminal of the third resistor is used to couple to the voltage reference terminal. The first terminal of the fourth resistor is coupled to the first terminal of the third resistor. The second terminal of the fourth resistor is used to couple to a power supply circuit.

[0021] In this embodiment, a third resistor is connected between the controlled terminal of the switching device (including the first and second switching devices) and the voltage reference terminal, and a fourth resistor is coupled between the controlled terminal of the switching device and the power supply circuit, forming a voltage regulation and biasing circuit for the controlled terminal of the switching device. The power supply circuit provides a stable bias voltage to the controlled terminal of the switching device through the fourth resistor, ensuring its reliable conduction under normal conditions. The fourth Zener diode and the third resistor clamp and regulate the voltage at the controlled terminal of the switching device, preventing malfunctions of the switching device caused by power supply voltage fluctuations. Based on this voltage regulation circuit 306, it can be ensured that the switching device is precisely disconnected only under extreme overvoltage conditions, with no switching action under normal operating conditions, avoiding interference to the audio signal caused by frequent disconnection of the switching device, and improving the stability of the audio signal output.

[0022] In one possible embodiment, the switching circuit further includes a fifth resistor, the first end of which is coupled to the first end of the third switching device, and the second end of which is coupled to the third end of the third switching device.

[0023] In this embodiment, a fifth resistor is connected across the first and third terminals of the third switching device. Before the detection circuit triggers the third switching device to conduct, the fifth resistor limits the current flowing into the third switching device, preventing damage from overcurrent caused by instantaneous high voltage at the detection terminal. Simultaneously, it divides the voltage to regulate the trigger voltage of the third switching device. The inclusion of a fifth resistor improves the reliability of the switching circuit and ensures continuous output stability.

[0024] In one possible embodiment, the audio protection circuit further includes a third protection circuit, which is coupled to the first branch, the second branch, the controlled terminal of the first switching device, and the controlled terminal of the second switching device, and is configured to: detect the voltage on the first branch and / or the second branch, and control the first switching device and / or the second switching device to disconnect when the voltage on the first branch and / or the second branch is greater than a second voltage threshold.

[0025] In this embodiment, a third protection circuit is added to the audio protection circuit and coupled to the first branch, the second branch, and the first and second switching devices to form a dual detection and control logic for secondary overvoltage protection. The third protection circuit can independently detect the voltage of the first and second branches. When the voltage of either branch exceeds the second voltage threshold, it directly controls the first and second switching devices to disconnect accordingly. The third protection circuit forms redundant protection with the switching circuit in the original second protection circuit, which can avoid overvoltage protection failure caused by switching circuit failure, further ensuring that the first and second branches disconnect under extreme overvoltage, and triggering the switching action only under this condition. Conventional overvoltage is still passively discharged by the first protection circuit, without frequent switching operations, which improves the reliability and fault tolerance of the overall overvoltage protection, reduces the interference of switching actions on the audio signal, and ensures continuous and stable audio output. In addition, the three-level protection is adapted to different overvoltage scenarios, taking into account both circuit safety and audio transmission performance.

[0026] Secondly, embodiments of this application provide an in-vehicle audio system, including the audio protection circuit described in the first aspect.

[0027] Thirdly, embodiments of this application provide a vehicle including the audio protection circuit as described in the first aspect, or the in-vehicle audio system as described in the second aspect. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of this application or the background art, the accompanying drawings used in the embodiments of this application will be described below.

[0029] Figure 1 This is a schematic diagram of the structure of a vehicle disclosed in an embodiment of this application; Figure 2 This is a schematic diagram of the structure of an in-vehicle audio system disclosed in an embodiment of this application; Figure 3 This is a schematic diagram of the structure of an audio protection circuit disclosed in an embodiment of this application. Figure 1 ; Figure 4 This is a schematic diagram of the operation of a first protection circuit disclosed in an embodiment of this application; Figure 5 This is a control flowchart of a third protection circuit disclosed in an embodiment of this application; Figure 6 This is a schematic diagram of the structure of an audio protection circuit disclosed in an embodiment of this application. Figure 2 .

[0030] Explanation of reference numerals in the attached figures: 1-Vehicle; 10 - In-vehicle audio system; 20 - In-vehicle speaker; 100 - Audio source module; 200 - Decoding circuit; 300 - Audio protection circuit; 301 - Audio processing circuit; 302 - Audio output circuit; 303 - First protection circuit; 304 - Second protection circuit; 305 - Third protection circuit; 306 - Voltage regulator circuit; 307 - Filtering circuit; 3041 - Switching circuit; 401 - Detection circuit; 501 - First Branch Road; 502 - Second Branch Road; D1 - First diode; D2 - Second diode; Dz1 - First Zener diode; Dz2 - Second Zener diode; Dz3 - Third Zener diode; Dz4 - Fourth Zener diode; Dz5 - Fifth Zener diode; R1 - First resistor; R2 - Second resistor; R3 - Third resistor; R4 - Fourth resistor; R5 - Fifth resistor; R6 - Sixth resistor; C1 - First capacitor; C2 - Second capacitor; L1 - First inductor; L2 - Second inductor; Q1 - First switching device; Q2 - Second switching device; Q3 - Third switching device; VCC - Power supply circuit; GND - Voltage reference terminal. Detailed Implementation

[0031] The terms “first,” “second,” etc., are used for descriptive purposes only and have no sequential or technical meaning, nor should they be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated.

[0032] In the description of the embodiments of this application, unless otherwise expressly specified and limited, the terms "coupled" and "connected" refer to the flow of current or signal from one conductor to another. A connection between A and B means that current or signal can flow from A to B and vice versa. A connection between A and B includes direct electrical connection and indirect electrical connection. A direct electrical connection between A and B means that A and B are electrically connected through physical contact. An indirect electrical connection between A and B means that A and B are electrically connected through C, where C can be at least one wire or device.

[0033] The embodiments of this application are described below with reference to the accompanying drawings.

[0034] Please see Figure 1 , Figure 1 This is a schematic diagram of the structure of a vehicle disclosed in an embodiment of this application. The vehicle can be, but is not limited to, a pure electric vehicle (PEV / BEV), a hybrid electric vehicle (HEV), a range-extended electric vehicle (REEV), a plug-in hybrid electric vehicle (PHEV), or a new energy vehicle.

[0035] Vehicle 1 includes an in-vehicle audio system 10 and an in-vehicle speaker 20 (also referred to as a loudspeaker).

[0036] In vehicle 1, the in-vehicle audio system 10 is used to acquire, decode, process, amplify and transmit audio signals to provide suitable electrical signals and power support for the in-vehicle speaker 20.

[0037] The car speaker 20 is used to convert the electrical signal output by the car audio system 10 into audible sound and output the sound.

[0038] Please see Figure 2 , Figure 2 This is a schematic diagram of the structure of an in-vehicle audio system 10 disclosed in an embodiment of this application.

[0039] The vehicle audio system 10 includes: an audio source module 100, a decoding circuit 200, and an audio protection circuit 300 connected in sequence.

[0040] The audio source module 100 serves as the signal input terminal of the vehicle audio system 10, used to acquire the initial audio signal and convert the initial audio signal into an initial digital signal.

[0041] The decoding circuit 200 is used to convert the initial digital signal output by the audio source module 100 into an analog audio signal and transmit the analog audio signal to the audio protection circuit 300.

[0042] The audio protection circuit 300 includes an audio processing circuit and an audio output circuit, which are used to amplify the power of the analog audio signal and output the processed audio signal to the vehicle speaker.

[0043] Optionally, a digital signal processor (DSP) is also provided between the decoding circuit 200 and the audio protection circuit 300 to optimize the analog audio signal, such as performing sound effect adjustment, channel allocation, noise suppression, and parameter matching.

[0044] In the audio protection circuit 300, the audio processing circuit is typically a semiconductor precision integrated circuit, composed of a large number of tiny transistors, capacitors, resistors, and other precision components. These components have extremely low withstand voltage and current thresholds. If overvoltage exists in the transmission line between the audio processing circuit and the audio output circuit, it can directly damage the audio processing circuit through electrical breakdown, thermal burnout, and surge impact. Therefore, an overvoltage protection structure is needed to prevent damage to the audio processing circuit from overvoltage signals.

[0045] In some embodiments, a control circuit is set up to collect the voltage on the transmission line, and software is used to determine whether there is an abnormality. If an abnormality is found, the switch set on the transmission line is controlled to open, thereby cutting off the audio processing circuit and protecting the audio processing circuit.

[0046] However, software-based detection and control suffers from slow response times, making it difficult to protect the audio processing circuit in a timely manner during voltage surges. Furthermore, in this embodiment, protection against overvoltage faults of varying degrees is achieved by disconnecting the audio processing circuit. This frequent switching not only accelerates switch aging but also interrupts the audio signal, causing distortion.

[0047] Therefore, this application provides an audio protection circuit, please refer to [link to relevant documentation]. Figure 3 , Figure 3 This is a schematic diagram of the structure of an audio protection circuit 300 disclosed in an embodiment of this application.

[0048] The audio protection circuit 300 includes: an audio processing circuit 301, an audio output circuit 302, and a first protection circuit 303.

[0049] The audio processing circuit 301 can be a power amplifier (PA) chip, coupled to the front-end decoding circuit or DSP, to process the input audio signal and output a pair of differential analog signals with opposite phases and equal amplitudes (i.e., the processed audio signal).

[0050] The audio processing circuit 301 and the audio output circuit 302 are connected through a first branch 501 and a second branch 502. The first branch 501 and the second branch 502 are used to transmit audio signals, and the audio output circuit 302 outputs the audio signal processed by the audio processing circuit 301.

[0051] Specifically, the first end of the audio output circuit 302 is coupled to the first end of the audio processing circuit 301 through the first branch 501, and the second end of the audio output circuit 302 is coupled to the second end of the audio processing circuit 301 through the second branch 502.

[0052] In this embodiment of the application, a first protection circuit 303 is provided between the audio processing circuit 301 and the audio output circuit 302.

[0053] The first protection circuit 303 is coupled between the first and second terminals of the audio processing circuit 301 to discharge the voltage on the first branch 501 and / or the second branch 502 when the voltage on the first branch 501 and / or the second branch 502 is greater than the first voltage threshold.

[0054] In this embodiment, a first protection circuit 303 is coupled between the first and second terminals of the audio processing circuit 301. When the voltage on any branch exceeds a first voltage threshold, the first protection circuit 303 directly discharges the overvoltage, quickly suppressing the branch overvoltage and preventing damage to the audio processing circuit. Based on the first protection circuit 303 provided in this application, there is no need for frequent switching, which avoids the problem of audio signal interruption and distortion caused by switching action, ensuring the continuity and stability of audio signal output and improving audio transmission quality.

[0055] In one possible implementation, combining Figure 3 ,like Figure 4 As shown, the first protection circuit 303 includes: a first diode D1, a second diode D2, and a first Zener diode Dz1.

[0056] A diode conducts from the anode to the cathode, and the forward conduction voltage of a diode depends on the type of diode.

[0057] For example, the diode can be a silicon-based diode with a forward conduction voltage of approximately 0.6 to 0.7 V.

[0058] When the anode of a Zener diode is connected to a high potential and the cathode to a low potential, the Zener diode conducts from the anode to the cathode. However, when the cathode of a Zener diode is connected to a high potential and the anode to a low potential, if the potential between the cathode and anode of the Zener diode is greater than its breakdown voltage, the Zener diode is reverse-broken down, forming a stable reverse conduction circuit. In this case, even if the reverse voltage fluctuates, the voltage across the Zener diode can be kept stable at a stable value.

[0059] In this embodiment, the anode of the first diode D1 is coupled to the first terminal of the audio processing circuit 301, the anode of the second diode D2 is coupled to the second terminal of the audio processing circuit 301, and the cathode of the second diode D2 is coupled to the cathode of the first diode D1. The anode of the first Zener diode Dz1 is used to couple to the voltage reference terminal GND, and the cathode of the first Zener diode Dz1 is coupled to the cathode of the second diode D2. The cathode of the first Zener diode Dz1 is also used to couple to the power supply circuit VCC.

[0060] In this embodiment, the power supply circuit VCC is used to output a stable voltage, such as 9V.

[0061] When the voltage on the first branch 501 and / or the second branch 502 is greater than the first voltage threshold, the first Zener diode Dz1 conducts from the cathode to the anode of the first Zener diode Dz1 to discharge the voltage on the first branch 501 and / or the second branch 502, so as to stabilize the voltage on the first branch 501 and / or the second branch 502 at the first voltage threshold.

[0062] In one example, when the voltage of the first branch 501 is greater than the first voltage threshold, the first Zener diode Dz1 conducts from its cathode to its anode. Current flows through the first diode D1 and the first Zener diode Dz1 to the voltage reference terminal GND, discharging the voltage on the first branch 501 to stabilize the voltage on the first branch 501 and / or the second branch 502 at the first voltage threshold. The schematic diagram of the first protection circuit 303 at this time is as follows: Figure 4 As shown.

[0063] In another example, when the voltage of the second branch 502 is greater than the first voltage threshold, the first Zener diode Dz1 conducts from the cathode to the anode of the first Zener diode Dz1. Current flows through the second diode D2 and the first Zener diode Dz1 to the voltage reference terminal GND, thereby discharging the voltage on the second branch 502 to stabilize the voltage on the second branch 502 and / or the voltage on the second branch 502 at the first voltage threshold.

[0064] In this embodiment, when the voltage on the first branch 501 and / or the second branch 502 exceeds the first voltage threshold, the first Zener diode Dz1 is reverse-broken down and conducts along its cathode to anode direction, forming an overvoltage discharge circuit across the audio processing circuit 301. The overvoltage of the first branch 501 and / or the second branch 502 is quickly discharged through this circuit. At the same time, relying on the reverse breakdown clamping characteristic of the first Zener diode Dz1, the voltage on the first branch 501 and / or the second branch 502 is precisely stabilized at the first voltage threshold. This achieves overvoltage protection, avoids sudden voltage changes from interfering with the audio signal, and ensures continuous and stable audio output without any switching action.

[0065] In some embodiments, such as Figure 3 As shown, the audio protection circuit 300 further includes a second protection circuit 304, which is used to disconnect the audio processing circuit 301 and the audio output circuit 302 from the hardware level when the voltage of the first branch 501 and / or the second branch 502 is greater than the second voltage threshold.

[0066] The second protection circuit 304 includes: a first switching device Q1, a second switching device Q2, and a switching circuit 3041.

[0067] The first switching device Q1 and the second switching device Q2 can be selected from metal-oxide-semiconductor field-effect transistors (MOSFETs), bipolar junction transistors (BJTs), insulated gate bipolar transistors (IGBTs), or junction field-effect transistors (JFETs).

[0068] The first switching device Q1 is disposed on the first branch 501. The first terminal of the first switching device Q1 is coupled to the audio processing circuit 301. The second terminal of the first switching device Q1 is turned on when the voltage signal at the controlled terminal of the first switching device Q1 is greater than or equal to the cutoff voltage, and turned off when the voltage signal received at the controlled terminal of the first switching device Q1 is less than the cutoff voltage.

[0069] The second switching device Q2 is disposed on the second branch 502. The first terminal of the second switching device Q2 is coupled to the audio processing circuit 301. The second terminal of the second switching device Q2 is turned on when the voltage signal at the controlled terminal of the second switching device Q2 is greater than or equal to the cutoff voltage, and turned off when the voltage signal received at the controlled terminal of the second switching device Q2 is less than the cutoff voltage.

[0070] The first terminal of the switching circuit 3041 is coupled to the first branch 501, the second terminal of the switching circuit 3041 is coupled to the second branch 502, and the third terminal of the switching circuit 3041 is coupled to the controlled terminal of the first switching device Q1 and the controlled terminal of the second switching device Q2.

[0071] In this embodiment, when the voltage of the first branch 501 is greater than the second voltage threshold, the voltage signal output from the third terminal of the switching circuit 3041 is less than the cutoff voltage, thereby causing the first switching device Q1 and the second switching device Q2 to disconnect. When the voltage of the second branch 502 is greater than the second voltage threshold, the voltage signal output from the third terminal of the switching circuit 3041 is less than the cutoff voltage, thereby causing the first switching device Q1 and the second switching device Q2 to disconnect.

[0072] In this embodiment, a second protection circuit is added to the audio protection circuit 300, employing a two-level protection logic. The second voltage threshold is higher than the first voltage threshold. Under normal conditions, the first protection circuit 303 clamps and discharges small overvoltages through the first Zener diode Dz1, without branch switching, thus avoiding signal interference and ensuring stable audio output. When the voltage of the first branch 501 and / or the second branch 502 exceeds the higher second voltage threshold, the second protection circuit 304 is triggered and cuts off the corresponding branch, achieving hardware protection against large overvoltages and preventing damage to the audio processing circuit 301 due to overvoltage. This two-level protection ensures the stability of audio output under normal operating conditions through passive discharge and addresses extreme overvoltages through circuit breaking protection, balancing audio performance and circuit safety. Furthermore, it eliminates the need for frequent switching, further maintaining output continuity.

[0073] In some embodiments, such as Figure 3 As shown, the audio protection circuit 300 also includes a third protection circuit 305.

[0074] The third protection circuit 305 can be a microcontroller unit (MCU). When the voltage of the first branch 501 and / or the second branch 502 is greater than the second voltage threshold, the audio processing circuit 301 is cut off from the software level.

[0075] The third protection circuit 305 is coupled to the first branch 501, the second branch 502, the controlled terminal of the first switching device Q1, and the controlled terminal of the second switching device Q2, respectively. It is used to detect the voltage on the first branch 501 and / or the second branch 502. When the voltage on the first branch 501 and / or the second branch 502 is greater than the second voltage threshold, it controls the first switching device Q1 and / or the second switching device Q2 to disconnect.

[0076] In one possible implementation, the control flowchart of the third protection circuit 305 is as follows: Figure 5 As shown.

[0077] Under normal conditions, the voltage of the first branch 501 and / or the second branch 502 is less than or equal to the second voltage threshold. If fluctuations occur in the first branch 501 and / or the second branch 502, the third protection circuit 305 detects that the voltage of the first branch 501 and / or the second branch 502 is greater than the second voltage threshold. The third protection circuit 305 controls the first switching device Q1 and the second switching device Q2 to open, cutting off the audio processing circuit 301. After the voltage returns to normal, the third protection circuit controls the first switching device Q1 and the second switching device Q2 to turn on. The voltage of the first branch 501 and / or the second branch 502 remains less than or equal to the second voltage threshold.

[0078] In some embodiments, when the switching circuit 3041 is in normal operation, the controlled terminals of the first switching device Q1 and the second switching device Q2 are detected and controlled by the switching circuit 3041.

[0079] Because there is a delay in the detection and control of the third protection circuit 305 in practical applications, a preset delay time can be set in this embodiment. When the third protection circuit 305 detects that the voltage of the first branch 501 and / or the second branch 502 is greater than the second voltage threshold, the third protection circuit 305 starts timing. If, after the preset delay time, the voltage of the first branch 501 and / or the second branch 502 is still greater than the second voltage threshold, it indicates that the switching circuit 3041 is faulty. The third protection circuit 305 outputs a control signal to control the controlled terminals of the first switching device Q1 and the second switching device Q2, causing the first switching device Q1 and the second switching device Q2 to disconnect, thus protecting the audio processing circuit 301.

[0080] Since the switching circuit 3041 in the second protection circuit 304 adopts a hardware structure, its response speed is extremely fast, and the preset delay time can be set according to the response time of the switching circuit 3041.

[0081] In this embodiment, a third protection circuit 305 is added to the audio protection circuit and coupled to the first branch 501, the second branch 502, and the first and second switching devices Q1 and Q2, forming a dual detection and control logic for secondary overvoltage protection. The third protection circuit 305 can independently detect the voltages of the first branch 501 and the second branch 502. When the voltage of either branch exceeds the second voltage threshold, it directly controls the first and second switching devices Q1 and Q2 to disconnect accordingly. The third protection circuit 305 forms redundant protection with the switching circuit 3041 in the original second protection circuit 304, which can avoid overvoltage protection failure caused by the failure of the switching circuit 3041, further ensuring that the first branch 501 and the second branch 502 are disconnected under extreme overvoltage, and the switching action is triggered only under this condition. Conventional overvoltage is still passively discharged by the first protection circuit 303, without frequent switching operations, which improves the reliability and fault tolerance of the overall overvoltage protection, reduces the interference of switching actions on the audio signal, and ensures continuous and stable audio output. In addition, the three-level protection is adapted to different overvoltage scenarios, taking into account both circuit safety and audio transmission performance.

[0082] In some embodiments, combined with Figure 3 ,like Figure 6 As shown. The audio protection circuit 300 includes: an audio processing circuit 301, an audio output circuit 302, a first protection circuit 303, a second protection circuit 304, a third protection circuit 305, a voltage regulator circuit 306, and a filter circuit 307.

[0083] The audio output circuit 302 includes a first output terminal and a second output terminal. The first output terminal is coupled to the first branch 501, and the second output terminal is coupled to the second branch 502.

[0084] In the first protection circuit 303, the anode of the first diode D1 is coupled to the first terminal of the audio processing circuit 301, the anode of the second diode D2 is coupled to the second terminal of the audio processing circuit 301, and the cathode of the second diode D2 is coupled to the cathode of the first diode D1. The anode of the first Zener diode Dz1 is used to couple to the voltage reference terminal GND, and the cathode of the first Zener diode Dz1 is coupled to the cathode of the second diode D2. The cathode of the first Zener diode Dz1 is also used to couple to the power supply circuit VCC.

[0085] When the voltage of the first branch 501 and / or the second branch 502 is greater than the first voltage threshold, the overvoltage on the first branch 501 and / or the second branch 502 is discharged to the voltage reference terminal GND through the first Zener diode Dz1.

[0086] In the second protection circuit 304, the first switching device Q1 is disposed on the first branch 501, the second switching device Q2 is disposed on the second branch 502, the first terminal of the switching circuit 3041 is coupled to the first branch 501, the second terminal of the switching circuit 3041 is coupled to the second branch 502, the third terminal of the switching circuit 3041 is coupled to the controlled terminal of the first switching device Q1 and the controlled terminal of the second switching device Q2, and the fourth terminal of the switching circuit 3041 is coupled to the voltage reference terminal GND.

[0087] When the voltage value at the first and / or second terminals of the switching circuit 3041 is greater than the second voltage threshold, the third terminal of the switching circuit 3041 is connected to the fourth terminal of the switching circuit.

[0088] In one possible implementation, the switching circuit 3041 includes: a detection circuit 401, a third switching device Q3, and a fifth resistor R5.

[0089] The third switching device Q3 can be a transistor, MOSFET, IGBT, or JFET.

[0090] The first end of the detection circuit 401 is coupled to the first branch 501, and the second end of the detection circuit 401 is coupled to the second branch 502.

[0091] The first terminal of the third switching device Q3 is coupled to the third terminal of the detection circuit 401, the second terminal of the third switching device Q3 is coupled to the controlled terminal of the first switching device Q1 and the controlled terminal of the second switching device Q2, and the third terminal of the third switching device Q3 is used to couple to the voltage reference terminal GND.

[0092] The first end of the fifth resistor R5 is coupled to the first end of the third switching device Q3, and the second end of the fifth resistor R5 is coupled to the third end of the third switching device Q3, which is used to stabilize the voltage between the first end and the third end of the third switching device Q3.

[0093] When the voltage of the first branch 501 is less than or equal to the second voltage threshold, the voltage value at the first terminal of the detection circuit 401 is less than or equal to the second voltage threshold, and the first and third terminals of the detection circuit 401 are cut off. When the voltage of the first branch 501 is greater than the second voltage threshold, the voltage value at the first terminal of the detection circuit 401 is greater than the second voltage threshold, and the first and third terminals of the detection circuit 401 are connected.

[0094] When the voltage of the second branch 502 is less than or equal to the second voltage threshold, the voltage value at the second terminal of the detection circuit 401 is less than or equal to the second voltage threshold, and the second and third terminals of the detection circuit 401 are cut off. When the voltage of the second branch 502 is greater than the second voltage threshold, the voltage value at the second terminal of the detection circuit 401 is greater than the second voltage threshold, and the second and third terminals of the detection circuit 401 are turned on.

[0095] When the voltage between the first terminal and the third terminal of the third switching device Q3 is greater than the turn-on voltage, the second terminal and the third terminal of the third switching device Q3 are turned on.

[0096] In one example, when the voltage of the first branch 501 is less than or equal to the second voltage threshold, the first and third terminals of the detection circuit 401 are cut off. The voltage between the first and third terminals of the third switching device Q3 is the voltage across the fifth resistor R5, which is less than the turn-on voltage of the third switching device Q3. At this time, the second and third terminals of the third switching device Q3 are cut off. The voltage at the controlled terminal of the first switching device Q1 is greater than the cut-off voltage, and the voltage at the controlled terminal of the second switching device Q2 is greater than the cut-off voltage; therefore, both the first switching device Q1 and the second switching device Q2 are turned on.

[0097] In another example, when the voltage in the second branch 502 is less than or equal to the second voltage threshold, the second and third terminals of the detection circuit 401 are cut off. The voltage between the first and third terminals of the third switching device Q3 is the voltage across the fifth resistor R5, which is less than the turn-on voltage of the third switching device Q3. At this time, the second and third terminals of the third switching device Q3 are cut off. The voltage at the controlled terminal of the first switching device Q1 is greater than the cut-off voltage, and the voltage at the controlled terminal of the second switching device Q2 is greater than the cut-off voltage; therefore, both the first switching device Q1 and the second switching device Q2 are turned on.

[0098] In another example, when the voltage of the first branch 501 is greater than the second voltage threshold, the first and third terminals of the detection circuit 401 are turned on. When the voltage between the first and third terminals of the third switching device Q3 is greater than the turn-on voltage of the third switching device Q3, the second and third terminals of the third switching device Q3 are turned on to pull down the voltage of the controlled terminals of the first switching device Q1 and the second switching device Q2 to the voltage reference terminal GND. When the voltage of the controlled terminal of the first switching device Q1 is less than the cutoff voltage, and the voltage of the controlled terminal of the second switching device Q2 is less than the cutoff voltage, both the first switching device Q1 and the second switching device Q2 are turned off to protect the audio processing circuit 301.

[0099] In another example, when the voltage in the second branch 502 is greater than the second voltage threshold, the second and third terminals of the detection circuit 401 are turned on. When the voltage between the first and third terminals of the third switching device Q3 is greater than the turn-on voltage of the third switching device Q3, the second and third terminals of the third switching device Q3 are turned on to pull down the voltages of the controlled terminals of the first switching device Q1 and the second switching device Q2 to the voltage reference terminal GND. When the voltage at the controlled terminal of the first switching device Q1 is less than the cutoff voltage, and the voltage at the controlled terminal of the second switching device Q2 is less than the cutoff voltage, both the first switching device Q1 and the second switching device Q2 are turned off to protect the audio processing circuit 301.

[0100] In the above embodiment, the voltage regulator circuit 306 includes: a fourth voltage regulator diode Dz4, a third resistor R3, and a fourth resistor R4.

[0101] The cathode of the fourth Zener diode Dz4 is coupled to the controlled terminal of the first switching device Q1 and the controlled terminal of the second switching device Q2. The anode of the fourth Zener diode Dz4 is used to couple to the voltage reference terminal GND. The first terminal of the third resistor R3 is coupled to the controlled terminals of the first switching device Q1 and the second switching device Q2. The second terminal of the third resistor R3 is used to couple to the voltage reference terminal GND. The first terminal of the fourth resistor R4 is coupled to the first terminal of the third resistor R3. The second terminal of the fourth resistor R4 is used to couple to the power supply circuit VCC.

[0102] When the voltage of the first branch 501 and / or the second branch 502 is less than or equal to the second voltage threshold, the fourth resistor R4 and the third resistor R3 divide the voltage, the voltage of the controlled terminal of the first switching device Q1 and the controlled terminal of the second switching device Q2 is equal to the voltage across the third resistor R3, and the voltage across the third resistor R3 is greater than or equal to the cutoff voltage of the first switching device Q1 and the second switching device Q2, and the first switching device Q1 and the second switching device Q2 are turned on.

[0103] In conjunction with the above embodiments, when the voltage of the first branch 501 and / or the second branch 502 is greater than the second voltage threshold, the detection circuit 401 is turned on to pull down the voltage of the controlled terminal of the first switching device Q1 and the controlled terminal of the second switching device Q2 to the voltage reference terminal GND, so that the first switching device Q1 and the second switching device Q2 are turned off.

[0104] In this embodiment, the third resistor R3 is connected between the controlled terminal of the switching devices (including the first switching device Q1 and the second switching device Q2) and the voltage reference terminal GND. The fourth resistor is coupled between the controlled terminal of the switching devices and the power supply circuit VCC, forming a voltage regulation and biasing circuit for the controlled terminal of the switching devices. The power supply circuit VCC provides a stable bias voltage to the controlled terminal of the switching devices through the fourth resistor R4, ensuring reliable conduction under normal conditions. The fourth Zener diode Dz4 and the third resistor R3 clamp and regulate the voltage at the controlled terminal of the switching devices, preventing malfunctions caused by power supply voltage fluctuations. Based on this voltage regulation circuit 306, it can be ensured that the switching devices are precisely disconnected only under extreme overvoltage conditions, with no switching action under normal operating conditions, avoiding interference to the audio signal from frequent disconnection of the switching devices and improving the stability of the audio signal output.

[0105] In one possible implementation, the detection circuit 401 includes: a second Zener diode Dz2, a first resistor R1, a third Zener diode Dz3, and a second resistor R2. The cathode of the second Zener diode Dz2 is coupled to the first branch 501, the anode of the second Zener diode Dz2 is coupled to the first terminal of the first resistor R1, and the second terminal of the first resistor R1 is coupled to the first terminal of the third switching device Q3. The cathode of the third Zener diode Dz3 is coupled to the second branch 502, the anode of the third Zener diode Dz3 is coupled to the first terminal of the second resistor R2, and the second terminal of the second resistor R2 is coupled to the first terminal of the third switching device Q3.

[0106] In this embodiment, when the voltage of the first branch 501 is greater than the first voltage threshold but less than or equal to the second voltage threshold, the second Zener diode Dz2 cannot be broken down, and the detection circuit 401 is turned off. If the voltage of the first branch 501 is greater than the second voltage threshold, the second Zener diode Dz2 is broken down in reverse, and the overvoltage signal flows to the third switching device Q3, thereby controlling the first switching device Q1 and the second switching device Q2 to open. Correspondingly, when the voltage of the second branch 502 is greater than the first voltage threshold but less than or equal to the second voltage threshold, the third Zener diode Dz3 cannot be broken down. If the voltage of the second branch 502 is greater than the second voltage threshold, the third Zener diode Dz3 is broken down in reverse, and the overvoltage signal flows to the third switching device Q3, thereby controlling the first switching device Q1 and the second switching device Q2 to open.

[0107] In this embodiment, a passive overvoltage detection unit is constructed using Zener diodes and resistors. The cathodes of the second Zener diode Dz2 and the third Zener diode Dz3 are connected to the first branch 501 and the second branch 502, respectively, and their anodes are connected to the first terminal of the third switching device Q3 via corresponding resistors. The reverse breakdown voltage of the Zener diodes matches a second voltage threshold. When the voltage of any branch exceeds the second threshold, the corresponding Zener diode reverse-breaks and conducts, inputting voltage to the first terminal of the third switching device Q3 through the resistor, causing the voltage between its three terminals to reach the conduction threshold, thereby pulling down the controlled terminal voltage of the branch switching devices (i.e., the first switching device Q1 and the second switching device Q2) to disconnect the branch. Since the detection circuit is a passive structure, there is no active control loss, and the switching is only triggered by extreme overvoltage. Under normal operating conditions, the first protection circuit discharges the overvoltage, without frequent switching actions, avoiding signal interference and ensuring stable audio output. At the same time, the two-stage protection accurately adapts to different overvoltage scenarios, balancing circuit protection reliability and audio output performance.

[0108] In some embodiments, the third protection circuit 305 controls the first switching device Q1 and the second switching device Q2 through the third switching device Q3. Specifically, a fifth Zener diode Dz5 and a sixth resistor R6 are provided between the third protection circuit 305 and the first terminal of the third switching device Q3.

[0109] The specific operating logic of the fifth Zener diode Dz5 and the sixth resistor R6 can be found in the detection circuit 401. When the third protection circuit 305 detects that the voltage of the first branch 501 and / or the second branch 502 is greater than the second voltage threshold, and the second protection circuit 304 does not operate, it outputs a control signal to the fifth Zener diode Dz5, causing the fifth Zener diode Dz5 to break down in reverse, thereby achieving the disconnection control of the first switching device Q1 and the second switching device Q2 to protect the audio processing circuit 301.

[0110] In some embodiments, such as Figure 6 As shown, the audio protection circuit 300 also includes a filter circuit 307.

[0111] The first end of the filter circuit 307 is coupled to the first end of the audio processing circuit 301, and the second end of the filter circuit 307 is coupled to the second end of the audio processing circuit 301.

[0112] The filter circuit 307 includes: a first capacitor C1, a first inductor L1, a second capacitor C2, and a second inductor L2. The first terminal of the first capacitor C1 is coupled to the first terminal of the audio processing circuit 301, and the second terminal of the first capacitor C1 is coupled to the voltage reference terminal GND. The first terminal of the first inductor L1 is coupled to the first capacitor C1, and the second terminal of the first inductor L1 is coupled to one terminal of the first switching device Q1. The first terminal of the second capacitor C2 is coupled to the second terminal of the audio processing circuit 301, and the second terminal of the second capacitor C2 is coupled to the voltage reference terminal GND. The first terminal of the second inductor L2 is coupled to the second capacitor C2, and the second terminal of the second inductor L2 is coupled to one terminal of the second switching device Q2.

[0113] In this embodiment, the filter circuit 307 is used to filter the audio signal processed by the audio processing circuit 301.

[0114] As can be seen from the above embodiments, the audio protection circuit 300 provided in this application provides three levels of protection. Specifically, the first protection circuit 303 implements level one protection, the second protection circuit 304 implements level two protection, and the third protection circuit 305 implements level three protection. When a voltage fluctuation with a low amplitude and short duration occurs in a branch (i.e., a voltage fluctuation greater than the first voltage threshold but less than or equal to the second voltage threshold), the first protection circuit 303 clamps and absorbs the voltage of the branch to maintain it at a safe level, allowing the audio protection circuit to operate normally. When the voltage fluctuation in the branch has a large amplitude (i.e., a voltage fluctuation greater than the second voltage threshold), the second protection circuit 304 pulls down the voltage at the controlled terminals of the first and second switching devices Q1 and Q2 through the third switching device Q3, disconnecting the branch and preventing overvoltage from affecting the audio processing circuit 301. If the second protection circuit 304 fails to disconnect in time for any reason, the third protection circuit 305 implements active control, outputting a control signal to disconnect the first and second switching devices Q1 and Q2.

[0115] The audio protection circuit 300 provided in this application integrates hardware fast protection and software monitoring protection, ensuring both instantaneous response speed and providing loop monitoring and multiple protection capabilities. It provides multiple protection paths for voltage fluctuations of different amplitudes. The hardware protection link has a short response time, effectively suppressing the impact of transient high voltage on the audio processing circuit 301. It avoids frequent circuit disconnection affecting audio signal output and provides rapid isolation in the event of a serious fault. Balancing practicality and economy, the audio protection circuit 300 improves stability and reliability, significantly enhancing the robustness and lifespan of the vehicle audio system 10.

[0116] It should be understood that the application of this application is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims. Those skilled in the art can understand that implementing all or part of the processes of the above embodiments and making equivalent changes according to the claims of this application still fall within the scope of this application.

Claims

1. An audio protection circuit, characterized in that, include: The audio processing circuit (301) is used to process the input audio signal; An audio output circuit (302) is provided, wherein the first end of the audio output circuit (302) is coupled to the first end of the audio processing circuit (301) through a first branch (501), and the second end of the audio output circuit (302) is coupled to the second end of the audio processing circuit (301) through a second branch (502), for outputting the audio signal processed by the audio processing circuit (301). The first protection circuit (303) is coupled between the first and second terminals of the audio processing circuit (301) and is used to discharge the voltage on the first branch (501) and / or the second branch (502) when the voltage on the first branch (501) and / or the second branch (502) is greater than the first voltage threshold.

2. The audio protection circuit according to claim 1, characterized in that, The first protection circuit (303) includes: The first diode (D1) has its anode coupled to the first terminal of the audio processing circuit (301); The second diode (D2) has its anode coupled to the second terminal of the audio processing circuit (301), and its cathode coupled to the cathode of the first diode (D1). The first Zener diode (Dz1) has its anode connected to a voltage reference terminal, and its cathode connected to the cathode of the second diode (D2). The cathode of the first Zener diode (Dz1) is also connected to a power supply circuit.

3. The audio protection circuit according to claim 2, characterized in that, When the voltage on the first branch (501) and / or the second branch (502) is greater than the first voltage threshold, the first Zener diode (Dz1) is turned on from the cathode to the anode of the first Zener diode (Dz1) to discharge the voltage on the first branch (501) and / or the second branch (502) so as to stabilize the voltage on the first branch (501) and / or the second branch (502) at the first voltage threshold.

4. The audio protection circuit according to claim 1, characterized in that, Also includes: The second protection circuit (304) is coupled between the audio processing circuit (301) and the audio output circuit (302) and is used to control the first branch (501) and / or the second branch (502) to disconnect when the voltage on the first branch (501) and / or the second branch (502) is greater than the second voltage threshold; the second voltage threshold is greater than the first voltage threshold.

5. The audio protection circuit according to claim 4, characterized in that, The second protection circuit (304) includes: The first switching device (Q1) is disposed on the first branch (501) and configured to disconnect when the voltage signal received at the controlled terminal of the first switching device (Q1) is less than the cutoff voltage. The second switching device (Q2) is disposed on the second branch (502) and configured to disconnect when the voltage signal received at the controlled terminal of the second switching device (Q2) is less than the cutoff voltage. A switching circuit (3041) is provided, wherein a first terminal of the switching circuit (3041) is coupled to a first branch (501), a second terminal of the switching circuit (3041) is coupled to a second branch (502), a third terminal of the switching circuit (3041) is coupled to a controlled terminal of a first switching device (Q1) and a controlled terminal of a second switching device (Q2); and a fourth terminal of the switching circuit (3041) is coupled to a voltage reference terminal and is configured such that when the voltage value of the first terminal and / or the second terminal of the switching circuit (3041) is greater than the second voltage threshold, the third terminal of the switching circuit (3041) is connected to the fourth terminal of the switching circuit (3041).

6. The audio protection circuit according to claim 5, characterized in that, The switching circuit (3041) includes: A detection circuit (401), wherein a first terminal of the detection circuit (401) is coupled to a first branch (501) and a second terminal of the detection circuit (401) is coupled to a second branch (502), is configured such that: when the voltage value at the first terminal of the detection circuit (401) is greater than a second voltage threshold, the first terminal is connected to the third terminal; and when the voltage value at the second terminal of the detection circuit (401) is greater than the second voltage threshold, the second terminal is connected to the third terminal. A third switching device (Q3) has its first terminal coupled to the third terminal of the detection circuit (401), and its second terminal coupled to the controlled terminal of the first switching device (Q1) and the controlled terminal of the second switching device (Q2). The third terminal of the third switching device (Q3) is used to couple to the voltage reference terminal and is configured such that when the voltage between the first terminal and the third terminal of the third switching device (Q3) is greater than the turn-on voltage, the second terminal of the third switching device (Q3) is turned on.

7. The audio protection circuit according to claim 6, characterized in that, The detection circuit (401) includes: The second Zener diode (Dz2) and the first resistor (R1) are connected. The cathode of the second Zener diode (Dz2) is coupled to the first branch (501), and the anode of the second Zener diode (Dz2) is coupled to the first end of the first resistor (R1). The second end of the first resistor (R1) is coupled to the first end of the third switching device (Q3). The third Zener diode (Dz3) and the second resistor (R2) are connected in the following ways: the cathode of the third Zener diode (Dz3) is coupled to the second branch (502), the anode of the third Zener diode (Dz3) is coupled to the first end of the second resistor (R2), and the second end of the second resistor (R2) is coupled to the first end of the third switching device (Q3).

8. The audio protection circuit according to claim 5, characterized in that, Also includes: A voltage regulator circuit (306) includes: A fourth Zener diode (Dz4) is provided, the cathode of which is coupled to the controlled terminal of the first switching device (Q1) and the second switching device (Q2), and the anode of which is coupled to the voltage reference terminal. The third resistor (R3) has its first end coupled to the controlled terminal of the first switching device (Q1) and the controlled terminal of the second switching device (Q2), and its second end is used to couple to the voltage reference terminal. The fourth resistor (R4) has its first end coupled to the first end of the third resistor (R3), and its second end is used to couple to the power supply circuit.

9. The audio protection circuit according to claim 6, characterized in that, The switching circuit (3041) also includes: The fifth resistor (R5) has its first end coupled to the first end of the third switching device (Q3), and its second end coupled to the third end of the third switching device (Q3).

10. The audio protection circuit according to claim 5, characterized in that, Also includes: The third protection circuit (305) is coupled to the first branch (501), the second branch (502), the controlled terminal of the first switching device (Q1), and the controlled terminal of the second switching device (Q2), respectively, and is configured to: detect the voltage on the first branch (501) and / or the second branch (502), and when the voltage on the first branch (501) and / or the second branch (502) is greater than the second voltage threshold, control the first switching device (Q1) and / or the second switching device (Q2) to disconnect.

11. A vehicle-mounted audio system, characterized in that, Includes the audio protection circuit as described in any one of claims 1-10.

12. A vehicle, characterized in that, Includes the audio protection circuit as described in any one of claims 1-10, or the vehicle audio system as described in claim 11.

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