Audio interface protection circuit, power amplifier device, loudspeaker, system and vehicle

Abstract

The present disclosure relates to an audio interface protection circuit, a power amplifier device, a loudspeaker, a system and a vehicle, and relates to the field of vehicle-mounted devices. The circuit comprises a first switch tube, a second switch tube, a third switch tube and a reverse protection circuit. The reverse protection circuit is connected between the control end of the third switch tube and a loudspeaker. The control end of the third switch tube is connected to the control end of the first switch tube and the second switch tube. The first switch tube and the second switch tube are used to connect an audio interface and the loudspeaker. When the output voltage of the audio interface is greater than a set threshold, the reverse protection circuit is reversely turned on to trigger the third switch tube to be saturated and turned on. When the third switch tube is saturated and turned on, the first switch tube and the second switch tube are in an off state to disconnect the loudspeaker from the audio interface. When the output voltage of the audio interface is greater than the set threshold, the current transmission between the audio interface and the loudspeaker can be disconnected, and the audio interface can be prevented from being burnt out.

Description

Technical Field

[0001] This disclosure relates to the field of vehicle-mounted equipment, and more specifically, to an audio interface protection circuit, a power amplifier, a speaker, a system, and a vehicle. Background Technology

[0002] Some vehicle equipment typically comes with an audio interface (PA) to drive external speakers to produce sound. These audio interfaces usually operate at a low voltage, while the equipment is often connected to many high-voltage harnesses, which provide voltages far exceeding the operating voltage of the internal audio interface (PA). If the external harnesses are worn out or if assembly line personnel negligently short-circuit the high-voltage harnesses and the audio interface, the audio interface will be unable to withstand the high voltage from the outside, thus burning out the audio interface. Utility Model Content

[0003] To overcome the problems existing in the related technologies, this disclosure provides an audio interface protection circuit, a power amplifier, a speaker, a system, and a vehicle.

[0004] According to a first aspect of the present disclosure, an audio interface protection circuit is provided, comprising: a first switch transistor, a second switch transistor, a third switch transistor, and a reverse protection circuit; the reverse protection circuit is connected between the control terminal of the third switch transistor and a speaker, the third switch transistor is connected to the control terminals of the first switch transistor and the second switch transistor, and the first switch transistor and the second switch transistor are used to connect the audio interface and the speaker; When the output voltage of the audio interface is greater than a set threshold, the reverse protection circuit is reverse-biased to trigger the third switch to saturate and conduct. When the third switch is saturated and conduct, the first switch and the second switch are in the off state to disconnect the speaker from the audio interface.

[0005] Optionally, the first and second switching transistors are both NMOS transistors, the third switching transistor is a transistor, and the reverse protection circuit includes a first diode and a second diode.

[0006] Optionally, the first diode and the second diode are Zener diodes; The source of the first switching transistor is connected to the first end of the audio interface, and the drain of the first switching transistor is connected to the first end of the speaker. The source of the second switching transistor is connected to the second terminal of the audio interface, and the drain of the second switching transistor is connected to the second terminal of the speaker. The gates of the first and second switching transistors are connected to the collector of the third switching transistor. The gate of the first switch, the gate of the second switch, and the collector of the third switch are connected to an external power supply. The base of the third switching transistor is connected to the anode of the first diode, the cathode of the first diode is connected to the drain of the first switching transistor and the first terminal of the speaker, the base of the third switching transistor is also connected to the anode of the second diode, and the cathode of the second diode is connected to the drain of the second switching transistor and the second terminal of the speaker. The emitter of the third switch is grounded.

[0007] Optionally, the gate of the first switch, the gate of the second switch, and the collector of the third switch are connected to the external power supply through a first resistor. The base of the third switch is connected to the positive terminal of the first diode through a second resistor; The base of the third switch is connected to the positive terminal of the second diode through a third resistor; The base of the third switching transistor is also grounded through a fourth resistor, and the collector of the third switching transistor is also grounded through a fifth resistor.

[0008] Optionally, it also includes: a third diode and a fourth diode; The negative terminal of the third diode is connected to the source terminal of the first switching transistor and the first terminal of the audio interface, and the positive terminal of the third diode is grounded. The negative terminal of the fourth diode is connected to the source terminal of the second switching transistor and the second terminal of the audio interface, while the positive terminal of the fourth diode is grounded.

[0009] Optionally, the third diode and the fourth diode are TVS diodes.

[0010] According to a second aspect of the present disclosure, a power amplifier device is provided, including the audio interface protection circuit described in the first aspect of the present disclosure, the power amplifier device being used to connect to a speaker through the audio interface protection circuit.

[0011] According to a third aspect of the present disclosure, a power amplifier device is provided, including the audio interface protection circuit described in the first aspect of the present disclosure, wherein the speaker is used to connect to the audio interface of the power amplifier device through the audio interface protection circuit.

[0012] According to a fourth aspect of the present disclosure, an audio interface protection system is provided, including the audio interface protection circuit described in the first aspect of the present disclosure, wherein the audio interface of the power amplifier device is connected to the speaker through the audio interface protection circuit.

[0013] According to a fifth aspect of the present disclosure, a vehicle is provided that includes the audio interface protection system described in the fourth aspect of the present disclosure.

[0014] The audio interface protection circuit, as described above, includes a first switch, a second switch, a third switch, and a reverse protection circuit. The reverse protection circuit is connected between the control terminal of the third switch and the speaker. The third switch is connected to the control terminals of the first and second switches, which connect the audio interface and the speaker. When the output voltage of the audio interface exceeds a set threshold, the reverse protection circuit reverse-biased conduction triggers the third switch to saturate and conduct. When the third switch is saturated and conducting, the first and second switches are in a cut-off state, disconnecting the speaker from the audio interface. This circuit allows the third switch to saturate and conduct when the output voltage of the audio interface exceeds a set threshold, thus cutting off the current transmission between the audio interface and the speaker and preventing damage to the audio interface caused by excessive output voltage.

[0015] Other features and advantages of this disclosure will be described in detail in the following detailed description section. Attached Figure Description

[0016] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic diagram of an audio interface protection circuit according to an exemplary embodiment.

[0017] Figure 2 This is a schematic diagram of an audio interface protection circuit according to an exemplary embodiment. Detailed Implementation

[0018] The specific embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the scope of this disclosure. In this disclosure, unless otherwise stated, directional terms such as "upper," "lower," "top," and "bottom" generally refer to the upper, lower, top, and bottom of the corresponding component in the direction of gravity during its use; "inner" and "outer" refer to the inner and outer dimensions relative to the outline of the component or structure itself. Furthermore, it should be noted that terms such as "first," "second," and "third" are used to distinguish one element from another and do not have sequential or importance implications. Additionally, in the description with reference to the accompanying drawings, the same reference numerals in different drawings denote the same elements.

[0019] Figure 1 This is a schematic diagram illustrating an audio interface protection circuit according to an exemplary embodiment. Figure 1 As shown, the audio interface protection circuit 100 includes: a first switching transistor 110, a second switching transistor 111, a third switching transistor 120, and a reverse protection circuit 150; The reverse protection circuit 150 is connected between the control terminal of the third switch transistor 120 and the speaker 300. The third switch transistor 120 is connected to the control terminals of the first switch transistor 110 and the second switch transistor 111. The first switch transistor 110 and the second switch transistor 111 are used to connect the audio interface 200 and the speaker 300. When the output voltage of the audio interface 200 is greater than a set threshold, the reverse protection circuit 150 is reverse-biased to trigger the third switch 120 to saturate and conduct. When the third switch 120 is saturated and conducting, the first switch 110 and the second switch 111 are in the off state to disconnect the speaker 300 from the audio interface 200.

[0020] For example, some devices in a vehicle have an audio interface 200 (PA) that can drive an external speaker 300 to produce sound. The operating voltage of the audio interface 200 is usually low, while the device may be connected to a high-voltage wiring harness. The voltage of this high-voltage wiring harness is usually much higher than the operating voltage of the audio interface 200. Therefore, if the external wiring harness is short-circuited to the audio interface 200 due to aging or negligence by assembly line personnel, the high voltage of the high-voltage wiring harness will enter the audio interface 200, causing an abnormal increase in the output voltage of the audio interface 200. The audio interface 200 may be unable to withstand the incoming high voltage, thus burning out the audio amplifier. Therefore, by connecting the audio interface protection circuit 100 between the audio interface 200 and the speaker 300, the current transmission between the audio interface 200 and the speaker 300 can be interrupted when the high voltage of the high-voltage wiring harness enters the audio interface 200, thereby preventing the audio interface 200 from burning out and ensuring the safe use and service life of the audio interface 200.

[0021] Optionally, the first switch 110 and the second switch 111 are both NMOS transistors, the third switch 120 is a transistor, and the reverse protection circuit 150 includes a first diode 151 and a second diode 152.

[0022] Optionally, the first diode 151 and the second diode 152 are Zener diodes; The source of the first switching transistor 110 is connected to the first end of the audio interface 200, and the drain of the first switching transistor 110 is connected to the first end of the speaker 300. The source of the second switching transistor 111 is connected to the second terminal of the audio interface 200, and the drain of the second switching transistor is connected to the second terminal of the speaker 300. The gate of the first switch 110 and the gate of the second switch 111 are connected to the collector of the third switch 120. The gate of the first switch 110, the gate of the second switch 111, and the collector of the third switch 120 are connected to the external power supply 140. The base of the third switch 120 is connected to the anode of the first diode 151, the cathode of the first diode 151 is connected to the drain of the first switch 110 and the first terminal of the speaker 300, the base of the third switch 120 is also connected to the anode of the second diode 152, and the cathode of the second diode 152 is connected to the drain of the second switch 111 and the second terminal of the speaker 300. The emitter of the third switch transistor 120 is grounded.

[0023] For example, the third switch 120 can be a transistor (NPN type transistor), and the first switch 110 and the second switch 111 can be NMOS transistors. The working principle of an NMOS transistor is to control its gate-source voltage V. GS (Gate voltage V) G -Source voltage V S This is used to achieve the on and off states. When the gate-source voltage V... GS >V th Time (V) th (where V is the cutoff voltage of the NMOS transistor). When the NMOS transistor is turned on, current can flow from the source to the drain. GS ≤V th When the NMOS transistor is in the off state, current cannot flow from the source to the drain of the NMOS transistor.

[0024] During the use of the audio interface 200, the input signal can be either a single-ended signal or a differential signal. For example, in... Figure 1 In the audio interface protection circuit 100 shown, when the input signal of the audio interface 200 is a single-ended signal, a working voltage can be applied only to the first or second end of the audio interface 200, thereby enabling audio playback through the first switch 110 or the second switch 111; when the input signal of the audio interface 200 is a differential signal, a working voltage can be applied to both the first and second ends of the audio interface 200, thereby enabling audio playback through the first switch 110 and the second switch 111. Therefore, the audio interface protection circuit 100 can achieve the protection function of the audio interface 200 in both cases of single-ended input and differential input.

[0025] In such Figure 1 In the audio interface protection circuit 100 shown, the source of the first switching transistor 110 is connected to the first terminal of the audio interface 200, the source of the second switching transistor 111 is connected to the second terminal of the audio interface 200, and the gates of the first switching transistor 110, the second switching transistor 111, and the collector of the third switching transistor 120 are all connected to the external power supply 140; therefore, the source voltage V of the first switching transistor 110 and the second switching transistor 111 is... S =V PA (V) PA (The output voltage of the audio interface 200) When the third switch 120 is in the off state, the third switch 120 is equivalent to an open switch, and the external power supply 140 can provide the turn-on voltage for the first switch 110 and the second switch 111. At this time, the gate voltage V of the first switch 110 and the second switch 111 is... G =V DD (V) DD (The voltage of the external power supply 140), the gate-source voltage V in the first switch 110 and the second switch 111 GS =V G -V S =V DD -V PA The gate-source voltage V in the first switch 110 and the second switch 111 GS >V th In this condition, the switching transistor is in the ON state, and the current output by the audio interface 200 can be transmitted to the speaker 300, thereby enabling audio playback. In summary, the voltage V of the external power supply 140... DD It should be at least greater than the cutoff voltage V of the NMOS transistor. th The sum of the maximum operating voltage allowed by the audio interface 200.

[0026] When the third switch 120 is in a saturated conduction state, it acts as a closed switch. At this time, the gate voltage V in the first switch 110 and the second switch 111 is... G =V CE (V) CE (This is the collector voltage of the third switch 120), therefore its gate-source voltage V GS =V G -V S =V CE -V PA It is understandable that the saturation conduction of a transistor refers to the situation where, when the base current of the transistor exceeds a preset value, the collector current reaches its maximum value, and the collector voltage V... CEIt is very low, typically less than 0.3V; therefore, when the third switch 120 is in saturation conduction, the gate-source voltage V in the first switch 110 and the second switch 111 is very low. GS <V th When the first switch 110 and the second switch 111 are in the off state, the current output by the audio interface 200 cannot be transmitted to the speaker 300, thereby protecting the audio interface 200.

[0027] For example, a Zener diode, also known as a Zener diode, is a special type of semiconductor diode that can be used to provide a stable reference voltage or perform simple voltage regulation. The working principle of a Zener diode is based on its reverse breakdown characteristic. When the reverse voltage entering the Zener diode reaches its reverse breakdown voltage, the current through the Zener diode will increase sharply, but the voltage across the diode remains relatively stable.

[0028] Therefore, in such Figure 1 In the audio interface protection circuit 100 shown, the base of the third switch 120 is connected to the anode of the first diode 151, the cathode of the first diode 151 is connected to the drain of the first switch 110 and the first terminal of the speaker 300, the base of the third switch 120 is also connected to the anode of the second diode 152, and the cathode of the second diode 152 is connected to the drain of the second switch 111 and the second terminal of the speaker 300; the output voltage V of the audio interface 200 PA When the reverse breakdown voltage of the first diode 151 or the second diode 152 is greater than the reverse breakdown voltage, the corresponding diode conducts in reverse. At this time, the current flowing through the diode increases and enters the base of the third switch 120. When the base current of the third switch 120 is greater than its preset value for saturation conduction, the third switch 120 is in a saturation conduction state, and the collector voltage V... CE Typically less than 0.3V, at this time, the gate-source voltage V of the first switch 110 and the second switch 111 is... GS =V G -V S =V CE -V PA Less than its cutoff voltage V th When the first switch 110 and the second switch 111 are in the off state, the current transmission between the audio interface 200 and the speaker 300 is interrupted, thus protecting the audio interface 200. The model of the first diode 151 and the second diode 152 can be determined based on the maximum allowable operating voltage of the audio interface 200.

[0029] For example, in one possible embodiment, the set threshold is the maximum allowable operating voltage of the audio interface 200. When the input of the audio interface 200 is a differential input, if the output voltage of the first terminal of the audio interface 200 is greater than the set threshold, the first diode 151 connected to the first terminal of the audio interface 200 through the first switch 110 is reverse-biased, the current flowing through the first diode 151 increases, and this current enters the base of the third switch 120, which can saturate and conduct the third switch 120, thereby lowering the collector voltage V of the third switch 120. CE (less than 0.3V), at this time the gate-source voltage V of the first switch 110 and the second switch 111 is... GS =V CE -V PA <V th If the first switch 110 and the second switch 111 are in the off state, the current transmission between the audio interface 200 and the speaker 300 can be disconnected, so as to avoid the problem of burning out the audio interface 200 due to excessive output voltage.

[0030] Optionally, the gate of the first switch 110, the gate of the second switch 111, and the collector of the third switch 120 are connected to the external power supply 140 through the first resistor 131. The base of the third switch 120 is connected to the positive terminal of the first diode 151 through the second resistor 132; The base of the third switch 120 is connected to the positive terminal of the second diode 152 through the third resistor 133; The base of the third switching transistor 120 is also grounded through the fourth resistor 134, and the collector of the third switching transistor 120 is also grounded through the fifth resistor 135.

[0031] For example, in such Figure 1In the audio interface protection circuit 100 shown, the first switch 110 and the second switch 111 can be NMOS transistors, and the third switch 120 can be an NPN transistor. The base of the third switch 120 is grounded through the fourth resistor 134, and the collector is grounded through the fifth resistor 135. The first resistor 131, the second resistor 132, the third resistor 133, the fourth resistor 134, and the fifth resistor 135 are current-limiting resistors (used to limit the current in their respective branches to prevent excessive current from burning out the connected components); the external power supply 1... 40 is connected to the gate of the NMOS transistor (i.e., the first switch transistor 110 and the second switch transistor 111) and the collector of the third switch transistor 120 through the first resistor 131, providing the turn-on voltage for the first switch transistor 110 and the second switch transistor 111; the second resistor 132 and the third resistor 133 are used to limit the magnitude of the base current entering the third switch transistor 120, so that the base current can saturate and turn on the third switch transistor 120, while avoiding excessive base current entering the third switch transistor 120, which would cause the third switch transistor 120 to burn out.

[0032] Furthermore, in one possible embodiment, since the second resistor 132 and the third resistor 133 can control the magnitude of the base current entering the third switching transistor 120, the reverse protection circuit 150 can be eliminated. The magnitude of the base current entering the third switching transistor 120 can be controlled by increasing the resistance values ​​of the second resistor 132 and the third resistor 133. In this case, the resistance values ​​of the second resistor 132 and the third resistor 133 can be determined by the maximum operating voltage allowed by the audio interface 200 and the base current that allows the third switching transistor 120 to enter the saturation conduction state.

[0033] The audio interface protection circuit, as described above, includes a first switch, a second switch, a third switch, and a reverse protection circuit. The reverse protection circuit is connected between the control terminal of the third switch and the speaker. The third switch is connected to the control terminals of the first and second switches, which connect the audio interface and the speaker. When the output voltage of the audio interface exceeds a set threshold, the reverse protection circuit reverse-biased conduction triggers the third switch to saturate and conduct. When the third switch is saturated and conducting, the first and second switches are in a cut-off state, disconnecting the speaker from the audio interface. This circuit allows the third switch to saturate and conduct when the output voltage of the audio interface exceeds a set threshold, thus cutting off the current transmission between the audio interface and the speaker and preventing damage to the audio interface caused by excessive output voltage.

[0034] Figure 2This is a schematic diagram of an audio interface protection circuit according to an exemplary embodiment, such as... Figure 2 As shown, the circuit also includes: a third diode 153 and a fourth diode 154; The negative terminal of the third diode 153 is connected to the source terminal of the first switching transistor 110 and the first terminal of the audio interface 200, and the positive terminal of the third diode 153 is grounded. The negative terminal of the fourth diode 154 is connected to the source terminal of the second switch 111 and the second terminal of the audio interface 200, while the positive terminal of the fourth diode 154 is grounded.

[0035] Optionally, the third diode 153 and the fourth diode 154 are TVS diodes.

[0036] For example, the third diode 153 and the fourth diode 154 can be TVS diodes, also known as transient voltage suppressor diodes, which can be used to protect electronic devices from transient high-energy shocks. Since electronic components such as Zener diodes, NMOS transistors, and NPN transistors also have a response time, which is usually very short, typically within 100ns, if the external voltage input to the audio interface 200 exceeds the maximum allowable operating voltage of the audio interface 200, there may be 100ns for the transient high voltage to enter the speaker 300 through the first switching transistor 110 and / or the second switching transistor 111. This could still lead to the audio interface 200 burning out. Therefore, to further improve the function of the audio interface protection circuit 100, the third diode 153 and the fourth diode 154 can be used to absorb the transient high energy to avoid the audio interface 200 burning out. Furthermore, this disclosure does not control the selection of the Zener diode, TVS diode, NMOS transistor, or NPN transistor.

[0037] The audio interface protection circuit, as described above, includes a first switch, a second switch, a third switch, and a reverse protection circuit. The reverse protection circuit is connected between the control terminal of the third switch and the speaker. The third switch is connected to the control terminals of the first and second switches, which connect the audio interface and the speaker. When the output voltage of the audio interface exceeds a set threshold, the reverse protection circuit reverse-biased conduction triggers the third switch to saturate and conduct. When the third switch is saturated and conducting, the first and second switches are in a cut-off state, disconnecting the speaker from the audio interface. This circuit allows the third switch to saturate and conduct when the output voltage of the audio interface exceeds a set threshold, thus cutting off the current transmission between the audio interface and the speaker and preventing damage to the audio interface caused by excessive output voltage.

[0038] In one possible embodiment, this disclosure provides a power amplifier device including the audio interface protection circuit described in the above embodiments, the power amplifier device being used to connect to a speaker through the audio interface protection circuit.

[0039] In one possible embodiment, this disclosure provides a loudspeaker including the audio interface protection circuit described in the above embodiments, the loudspeaker being used to connect to the audio interface of a power amplifier device through the audio interface protection circuit.

[0040] In one possible embodiment, this disclosure provides an audio interface protection system, including: the audio interface protection circuit, audio interface, and speaker described in the above embodiments.

[0041] In yet another possible embodiment, this disclosure provides a vehicle including: the audio interface protection system described in the above embodiments.

[0042] The preferred embodiments of the present disclosure have been described in detail above with reference to the accompanying drawings. However, the present disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present disclosure, various simple modifications can be made to the technical solutions of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.

[0043] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0044] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

Claims

1. An audio interface protection circuit, characterized in that, include: First switching transistor, second switching transistor, third switching transistor, reverse protection circuit; The reverse protection circuit is connected between the control terminal of the third switch and the speaker. The third switch is connected to the control terminals of the first switch and the second switch. The first switch and the second switch are used to connect the audio interface and the speaker. When the output voltage of the audio interface is greater than a set threshold, the reverse protection circuit is reverse-biased to trigger the third switch to saturate and conduct. When the third switch is saturated and conduct, the first switch and the second switch are in the off state to disconnect the speaker from the audio interface.

2. The protection circuit according to claim 1, characterized in that, The first and second switching transistors are both NMOS transistors, the third switching transistor is a bipolar transistor, and the reverse protection circuit includes a first diode and a second diode.

3. The protection circuit according to claim 2, characterized in that, The first diode and the second diode are Zener diodes; The source of the first switching transistor is connected to the first end of the audio interface, and the drain of the first switching transistor is connected to the first end of the speaker. The source of the second switching transistor is connected to the second terminal of the audio interface, and the drain of the second switching transistor is connected to the second terminal of the speaker. The gates of the first and second switching transistors are connected to the collector of the third switching transistor. The gate of the first switch, the gate of the second switch, and the collector of the third switch are connected to an external power supply. The base of the third switching transistor is connected to the anode of the first diode, the cathode of the first diode is connected to the drain of the first switching transistor and the first terminal of the speaker, the base of the third switching transistor is also connected to the anode of the second diode, and the cathode of the second diode is connected to the drain of the second switching transistor and the second terminal of the speaker. The emitter of the third switch is grounded.

4. The protection circuit according to claim 3, characterized in that, The gate of the first switch, the gate of the second switch, and the collector of the third switch are connected to the external power supply through a first resistor. The base of the third switching transistor is connected to the positive terminal of the first diode through a second resistor; The base of the third switch is connected to the positive terminal of the second diode through a third resistor; The base of the third switching transistor is also grounded through a fourth resistor, and the collector of the third switching transistor is also grounded through a fifth resistor.

5. The protection circuit according to claim 2, characterized in that, Also includes: Third diode and fourth diode; The negative terminal of the third diode is connected to the source terminal of the first switching transistor and the first terminal of the audio interface, and the positive terminal of the third diode is grounded. The negative terminal of the fourth diode is connected to the source terminal of the second switching transistor and the second terminal of the audio interface, while the positive terminal of the fourth diode is grounded.

6. The protection circuit according to claim 5, characterized in that, The third diode and the fourth diode are TVS diodes.

7. A power amplifier device, characterized in that, The amplifier includes the audio interface protection circuit according to any one of claims 1-6, and is used to connect to a speaker through the audio interface protection circuit.

8. A loudspeaker, characterized in that, Includes the audio interface protection circuit according to any one of claims 1-6, wherein the speaker is used to connect to the audio interface of the power amplifier device through the audio interface protection circuit.

9. An audio system, characterized in that, The device includes a power amplifier, a speaker, and an audio interface protection circuit as described in any one of claims 1-6, wherein the audio interface of the power amplifier is connected to the speaker through the audio interface protection circuit.

10. A vehicle, characterized in that, Includes the audio system as described in claim 9.

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