Audio output circuit and vehicle-mounted control system

Abstract

The utility model discloses an audio output circuit and a vehicle-mounted control system. The audio output circuit comprises an operational amplifier circuit and a conversion circuit. An input end of the operational amplifier circuit is connected with an audio control circuit of the vehicle-mounted control system, an output end of the operational amplifier circuit is connected with audio equipment of the vehicle-mounted control system, and a first power supply end of the operational amplifier circuit is connected with a power supply of the vehicle-mounted control system; the input end of the conversion circuit is connected with a step-down circuit of the vehicle-mounted control system, and the output end of the conversion circuit is connected with the second power supply end of the operational amplifier circuit. According to the utility model, circuit cost can be reduced and radiation interference can be avoided.

Description

TECHNICAL FIELD

[0001] The utility model relates to vehicle-mounted system technical field especially, relates to an audio output circuit and vehicle-mounted control system. BACKGROUND

[0002] The effective amplitude of the audio output in the vehicle-mounted control system is usually required to be greater than 4V, and the power supply voltage of the vehicle-mounted control system is usually 12V, in order to meet the requirement that the effective amplitude is greater than 4V, the power supply voltage of the audio output circuit usually needs 18V, therefore, the prior art needs to use DC-DC converter to boost the voltage of 12V to 18V, but this not only increases the circuit cost, but also exists radiation interference. SUMMARY

[0003] The utility model provides an audio output circuit and vehicle-mounted control system, it aims at solving the problem of higher circuit cost and existing radiation interference caused by the current audio output circuit needing to use DC-DC converter to boost.

[0004] In a first aspect, the utility model provides an audio output circuit, be applied to vehicle-mounted control system, the audio output circuit includes operational amplifier circuit and conversion circuit, the input of operational amplifier circuit is connected with the audio control circuit of vehicle-mounted control system, the output of operational amplifier circuit is connected with the audio equipment of vehicle-mounted control system, and the first power supply end of operational amplifier circuit is connected with the power supply of vehicle-mounted control system, the input of conversion circuit is connected with the voltage reduction circuit of vehicle-mounted control system, and the output of conversion circuit is connected with the second power supply end of operational amplifier circuit.

[0005] Further, the operational amplifier circuit includes a first operational amplifier circuit and a second operational amplifier circuit, the input of the first operational amplifier circuit and the input of the second operational amplifier circuit are connected with the audio control circuit, the output of the first operational amplifier circuit and the output of the second operational amplifier circuit are connected with the audio equipment, the first power supply end of the first operational amplifier circuit and the first power supply end of the second operational amplifier circuit are connected with the power supply, and the second power supply end of the first operational amplifier circuit and the second power supply end of the second operational amplifier circuit are connected with the conversion circuit.

[0006] Further, the first operational amplifier circuit includes a first operational amplifier, the noninverting input of the first operational amplifier is connected with a reference end, the inverting input of the first operational amplifier is connected with the audio control circuit, the output of the first operational amplifier is connected with the audio equipment, the positive pole of the first operational amplifier is connected with the power supply as the first power supply end, and the negative pole of the first operational amplifier is connected with the conversion circuit as the second power supply end.

[0007] Further, the first operational amplifier circuit further comprises a first resistor, a second resistor and a first capacitor; one end of the first resistor is connected with the audio control circuit, the other end of the first resistor is connected with one end of the first capacitor and one end of the second resistor respectively, the other end of the second resistor is connected with the inverting input terminal of the first operational amplifier, the other end of the first capacitor is grounded.

[0008] Further, the first operational amplifier circuit further comprises a third resistor, a fourth resistor, a second capacitor and a third capacitor; one end of the third resistor is connected with the first resistor, the other end of the third resistor is connected with one end of the second capacitor and one end of the fourth resistor respectively, the other end of the second capacitor is connected with the inverting input terminal of the first operational amplifier, the other end of the fourth resistor is connected with one end of the third capacitor, the other end of the third capacitor is connected with the audio device.

[0009] Further, the second operational amplifier circuit comprises a second operational amplifier, the non-inverting input terminal of the second operational amplifier is connected with the reference terminal, the inverting input terminal of the second operational amplifier is connected with the audio control circuit, the output terminal of the second operational amplifier is connected with the audio device; the positive electrode of the second operational amplifier is connected with the power supply as the first power supply terminal, the negative electrode of the second operational amplifier is connected with the conversion circuit as the second power supply terminal.

[0010] Further, the first operational amplifier circuit further comprises a fifth resistor, a sixth resistor and a fourth capacitor; one end of the fifth resistor is connected with the audio control circuit, the other end of the fifth resistor is connected with one end of the fourth capacitor and one end of the sixth resistor respectively, the other end of the sixth resistor is connected with the inverting input terminal of the second operational amplifier, the other end of the fourth capacitor is grounded.

[0011] Further, the first operational amplifier circuit further comprises a seventh resistor, an eighth resistor, a fifth capacitor and a sixth capacitor; one end of the seventh resistor is connected with the fifth resistor, the other end of the seventh resistor is connected with one end of the fifth capacitor and one end of the eighth resistor respectively, the other end of the fifth capacitor is connected with the inverting input terminal of the second operational amplifier, the other end of the eighth resistor is connected with one end of the sixth capacitor, the other end of the sixth capacitor is connected with the audio device.

[0012] Further, the conversion circuit comprises a seventh capacitor, an eighth capacitor, a ninth capacitor, a first diode, a second diode and a first inductor; one end of the seventh capacitor is connected with the voltage reduction circuit, the other end of the seventh capacitor is connected with the negative pole of the first diode and the negative pole of the second diode respectively, the positive pole of the first diode is grounded, the positive pole of the second diode is connected with one end of the eighth capacitor, one end of the ninth capacitor and one end of the first inductor respectively, the other end of the eighth capacitor and the other end of the ninth capacitor are both grounded, and the other end of the first inductor is connected with the second power supply end of the operational amplifier circuit.

[0013] In a second aspect, the utility model also provides a vehicle-mounted control system, it includes audio control circuit, audio equipment, power supply, voltage reduction circuit and the audio output circuit of any one described above.

[0014] The vehicle-mounted control system provided by the utility model comprises an audio control circuit, an audio equipment, a power supply, a voltage reduction circuit and an audio output circuit, the audio output circuit comprises an operational amplifier circuit and a conversion circuit, the operational amplifier circuit is used for connecting the audio control circuit and the audio equipment, can amplify the audio signal output by the audio control circuit and then transmit the audio signal to the audio equipment, meanwhile, the first power supply end of the operational amplifier circuit is connected with the power supply, and the second power supply end thereof is connected with the voltage reduction circuit through the conversion circuit, can be directly powered by the power supply of the vehicle-mounted control system, does not need to set a DC-DC converter to boost, reduces the circuit cost, and avoids the radiation interference caused by the DC-DC converter. BRIEF DESCRIPTION OF DRAWINGS

[0015] In order to more clearly illustrate the technical scheme of the utility model, the following will briefly introduce the drawings needed to be used in the embodiment description, obviously, the drawings in the following description are some embodiments of the utility model, and those skilled in the art can also obtain other drawings according to these drawings without creating labor.

[0016] Figure 1 The block schematic diagram of the audio output circuit provided by the first embodiment of the utility model is shown in the figure.

[0017] Figure 2 The block schematic diagram of the audio output circuit provided by the second embodiment of the utility model is shown in the figure.

[0018] Figure 3 The circuit diagram of the first operational amplifier circuit of the audio output circuit provided by an embodiment of the utility model is shown in the figure.

[0019] Figure 4 The circuit diagram of the second operational amplifier circuit of the audio output circuit provided by an embodiment of the utility model is shown in the figure.

[0020] Figure 5 The circuit diagram of the conversion circuit of the audio output circuit is provided for an embodiment of the utility model. DETAILED DESCRIPTION

[0021] The technical solutions in the utility model will be described clearly and completely below in combination with the drawings in the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, rather than all the embodiments. Based on the embodiments in the utility model, all the other embodiments obtained by the ordinary skilled in the art without making creative efforts belong to the protection scope of the utility model.

[0022] It should be understood that the terms "comprising" and "including" as used in the specification and the appended claims indicate the presence of the recited features, integers, steps, operations, elements, and / or components but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0023] It should also be understood that the terms used in the utility model specification are only for the purpose of describing specific embodiments and are not intended to limit the utility model. As used in the utility model specification and the appended claims, the singular forms "a", "an" and "the" are intended to include the plural forms unless the context clearly indicates otherwise. It should be further understood that the term "and / or" as used in the utility model specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes these combinations.

[0024] Referring to Figures 1 to 5 , Figure 1 The block schematic diagram of the audio output circuit 100 is provided for the first embodiment of the utility model; Figure 2 The block schematic diagram of the audio output circuit 100 is provided for the second embodiment of the utility model; Figure 3 The circuit diagram of the first operational amplifier circuit 11 of the audio output circuit 100 is provided for an embodiment of the utility model; Figure 4 The circuit diagram of the second operational amplifier circuit 12 of the audio output circuit 100 is provided for an embodiment of the utility model; Figure 5 The circuit diagram of the conversion circuit 20 of the audio output circuit 100 is provided for an embodiment of the utility model. As Figure 1The utility model provides an audio output circuit 100 including an operational amplifier circuit 10 and a conversion circuit 20, the input of the operational amplifier circuit 10 is connected with the audio control circuit 200 of vehicle control system, the output of the operational amplifier circuit 10 is connected with the audio equipment 300 of vehicle control system, and the first power supply end of the operational amplifier circuit 10 is connected with the power supply 400 of vehicle control system, the input of the conversion circuit 20 is connected with the voltage reduction circuit 500 of vehicle control system, and the output of the conversion circuit 20 is connected with the second power supply end of the operational amplifier circuit 10.

[0025] Specifically, the vehicle control system can include an audio control circuit 200, an audio device 300, a power supply 400, a voltage reduction circuit 500 and an audio output circuit 100. The audio control circuit 200 can include a SOC, i.e., a digital audio processor, for processing audio signals and then outputting the processed audio signals to the audio output circuit 100. The audio output circuit 100 is connected with the audio control circuit 200 and the audio device 300 respectively, for outputting the audio signals output by the audio control circuit 200 to the audio device 300. The power supply 400 can be a battery power supply of the vehicle control system, and its supply voltage is usually 12V.

[0026] The audio output circuit 100 can include an operational amplifier circuit 10 and a conversion circuit 20. The input of the operational amplifier circuit 10 is connected with the audio control circuit 200, and its output is connected with the audio device 300, for outputting the audio signals output by the audio control circuit 200 to the audio device 300. Meanwhile, the first power supply end of the operational amplifier circuit 10 is connected with the power supply 400, and its second power supply end is connected with the conversion circuit 20. The first power supply end can be positive, the second power supply end can be negative, and the power supply 400 can be a battery power supply. Thus, the positive supply voltage can be 12V. The conversion circuit 20 is connected with the voltage reduction circuit 500, and its voltage can be -5V. Thus, the negative supply voltage is -5V, and the operational amplifier circuit 10 can be powered without relying on a DC-DC step-up converter. Thus, the operational amplifier circuit 10 can output the audio signals to the audio device 300.

[0027] As a further embodiment, the operational amplifier circuit 10 comprises a first operational amplifier circuit 11 and a second operational amplifier circuit 12; the input end of the first operational amplifier circuit 11 and the input end of the second operational amplifier circuit 12 are both connected with the audio control circuit 200, the output end of the first operational amplifier circuit 11 and the output end of the second operational amplifier circuit 12 are both connected with the audio device 300; the first power supply end of the first operational amplifier circuit 11 and the first power supply end of the second operational amplifier circuit 12 are both connected with the power supply 400; the second power supply end of the first operational amplifier circuit 11 and the second power supply end of the second operational amplifier circuit 12 are both connected with the conversion circuit 20.

[0028] Among them, the input end of the first operational amplifier circuit 11 and the second operational amplifier circuit 12 are both connected with the audio control circuit 200, the first operational amplifier circuit 11 is used for receiving the left channel audio signal, and the second operational amplifier circuit 12 is used for receiving the right channel audio signal. At the same time, the output end of the first operational amplifier circuit 11 and the second operational amplifier circuit 12 are both connected with the audio device 300, the first operational amplifier circuit 11 is used for outputting the left channel audio signal to the audio device 300, and the second operational amplifier circuit 12 is used for outputting the right channel audio signal to the audio device 300.

[0029] At the same time, the first power supply end of the first operational amplifier circuit 11 and the second operational amplifier circuit 12 are both connected with the power supply 400, and the second power supply end of the two is also connected with the conversion circuit 20, which is powered by the power supply 400.

[0030] As a further embodiment, the first operational amplification circuit 11 comprises a first operational amplifier U1, the non-inverting input terminal of the first operational amplifier U1 is connected with a reference terminal, the inverting input terminal of the first operational amplifier U1 is connected with the audio control circuit 200, and the output terminal of the first operational amplifier U1 is connected with the audio device 300; the positive terminal of the first operational amplifier U1 is connected with the power supply 400 as the first power supply terminal, and the negative terminal of the first operational amplifier U1 is connected with the conversion circuit 20 as the second power supply terminal. As a further embodiment, the first operational amplification circuit 11 further comprises a first resistor R1, a second resistor R2, and a first capacitor C1; one end of the first resistor R1 is connected with the audio control circuit 200, the other end of the first resistor R1 is connected with one end of the first capacitor C1 and one end of the second resistor R2 respectively, the other end of the second resistor R2 is connected with the inverting input terminal of the first operational amplifier U1, and the other end of the first capacitor C1 is grounded. As a further embodiment, the first operational amplification circuit 11 further comprises a third resistor R3, a fourth resistor R4, a second capacitor C2, and a third capacitor C3; one end of the third resistor R3 is connected with the first resistor R1, the other end of the third resistor R3 is connected with one end of the second capacitor C2 and one end of the fourth resistor R4 respectively, the other end of the second capacitor C2 is connected with the inverting input terminal of the first operational amplifier U1, the other end of the fourth resistor R4 is connected with one end of the third capacitor C3, and the other end of the third capacitor C3 is connected with the audio device 300.

[0031] In the first operational amplification circuit 11, the first operational amplifier U1, the first resistor R1, the second resistor R2, the first capacitor C1, the third resistor R3, the fourth resistor R4, the second capacitor C2, and the third capacitor C3 are connected as shown in the figure. The inverting input terminal of the first operational amplifier U1 is connected with the audio control circuit 200 through the second resistor R2 and the first resistor R1, the non-inverting input terminal of the first operational amplifier U1 is connected with a reference terminal, and the output terminal of the first operational amplifier U1 is connected with the audio device 300 through the fourth resistor R4 and the third capacitor C3. In addition, the positive terminal of the first operational amplifier U1 is connected with the power supply 400 as the first power supply terminal, and the negative terminal of the first operational amplifier U1 is connected with the conversion circuit 20 as the second power supply terminal. The power supply 400 can be a battery power supply.

[0032] As a further embodiment, the second operational amplifier circuit 12 comprises a second operational amplifier U2, the non-inverting input terminal of the second operational amplifier U2 is connected with the reference terminal, the inverting input terminal of the second operational amplifier U2 is connected with the audio control circuit 200, and the output terminal of the second operational amplifier U2 is connected with the audio device 300; the positive terminal of the second operational amplifier U2 is connected with the power supply 400 as the first power supply terminal, and the negative terminal of the second operational amplifier U2 is connected with the conversion circuit 20 as the second power supply terminal. As a further embodiment, the first operational amplifier circuit 11 further comprises a fifth resistor R5, a sixth resistor R6, and a fourth capacitor C4; one end of the fifth resistor R5 is connected with the audio control circuit 200, the other end of the fifth resistor R5 is connected with one end of the fourth capacitor C4 and one end of the sixth resistor R6 respectively, the other end of the sixth resistor R6 is connected with the inverting input terminal of the second operational amplifier U2, and the other end of the fourth capacitor C4 is grounded. As a further embodiment, the first operational amplifier circuit 11 further comprises a seventh resistor R7, an eighth resistor R8, a fifth capacitor C5, and a sixth capacitor C6; one end of the seventh resistor R7 is connected with the fifth resistor R5, the other end of the seventh resistor R7 is connected with one end of the fifth capacitor C5 and one end of the eighth resistor R8 respectively, the other end of the fifth capacitor C5 is connected with the inverting input terminal of the second operational amplifier U2, the other end of the eighth resistor R8 is connected with one end of the sixth capacitor C6, and the other end of the sixth capacitor C6 is connected with the audio device 300.

[0033] The structure of the second operational amplifier circuit 12 is the same as that of the first operational amplifier circuit 11, and the principle will not be described here.

[0034] As a further embodiment, the conversion circuit 20 comprises a seventh capacitor C7, an eighth capacitor C8, a ninth capacitor C9, a first diode D1, a second diode D2, and a first inductor L1; one end of the seventh capacitor C7 is connected with the voltage reduction circuit 500, the other end of the seventh capacitor C7 is connected with the negative terminal of the first diode D1 and the negative terminal of the second diode D2 respectively, the positive terminal of the first diode D1 is grounded, the positive terminal of the second diode D2 is connected with one end of the eighth capacitor C8, one end of the ninth capacitor C9, and one end of the first inductor L1 respectively, the other end of the eighth capacitor C8 and the other end of the ninth capacitor C9 are both grounded, and the other end of the first inductor L1 is connected with the second power supply terminal of the operational amplifier circuit 10.

[0035] The conversion circuit 20 can include three capacitors and two diodes, namely a seventh capacitor C7, an eighth capacitor C8, a ninth capacitor C9, a first diode D1 and a second diode D2, the negative electrode of the first diode D1 and the negative electrode of the second diode D2 are connected with the voltage reduction circuit 500 through the seventh capacitor C7, the positive electrode of the second diode D2 is connected with the second power supply end of the operational amplifier circuit 10 through the first inductor L1, for example, the positive electrode of the second diode D2 is connected with the negative electrode of the first operational amplifier U1 and the negative electrode of the second operational amplifier U2 through the first inductor L1, for providing a voltage of-5V.

[0036] The utility model further provides a vehicle control system, the vehicle control system includes audio control circuit 200, audio equipment 300, power supply 400, voltage reduction circuit 500 and the audio output circuit 100 of any one in above-mentioned embodiment, the audio output circuit 100 includes operational amplifier circuit 10 and conversion circuit 20, the input of operational amplifier circuit 10 is connected with the audio control circuit 200 of vehicle control system, the output of operational amplifier circuit 10 is connected with the audio equipment 300 of vehicle control system, and the first power supply end of operational amplifier circuit 10 is connected with the power supply 400 of vehicle control system, the input of conversion circuit 20 is connected with the voltage reduction circuit 500 of vehicle control system, and the output of conversion circuit 20 is connected with the second power supply end of operational amplifier circuit 10.

[0037] Specifically, the vehicle control system can include audio control circuit 200, audio equipment 300, power supply 400, voltage reduction circuit 500 and audio output circuit 100. The audio control circuit 200 can include a SOC, that is, a digital audio processor, for processing audio signals, and then outputting the processed audio signals to the audio output circuit 100. The audio output circuit 100 is connected with the audio control circuit 200 and the audio equipment 300 respectively, for outputting the audio signals output by the audio control circuit 200 to the audio equipment 300. The power supply 400 can be a battery power supply of the vehicle control system, and the supply voltage thereof is usually 12V.

[0038] The audio output circuit 100 can include an operational amplifier circuit 10 and a conversion circuit 20, the input end of the operational amplifier circuit 10 is connected with the audio control circuit 200, the output end of the operational amplifier circuit 10 is connected with the audio equipment 300, and the operational amplifier circuit 10 is used for outputting the audio signal output by the audio control circuit 200 to the audio equipment 300. Meanwhile, the first power supply end of the operational amplifier circuit 10 is connected with the power supply 400, and the second power supply end of the operational amplifier circuit 10 is connected with the conversion circuit 20, the first power supply end can be a positive electrode, the second power supply end can be a negative electrode, the power supply 400 can be a battery power supply, and then the positive electrode power supply voltage can be 12V. The conversion circuit 20 is connected with the voltage reduction circuit 500, which can be-5V, and then the negative electrode power supply voltage is-5V, thereby the operational amplifier circuit 10 can be powered without relying on the DC-DC voltage converter, so that the operational amplifier circuit 10 can output the audio signal to the audio equipment 300.

[0039] The audio output circuit of the utility model, the operational amplifier circuit is used for connecting the audio control circuit and the audio equipment, can send the audio signal output by the audio control circuit to the audio equipment after amplification, simultaneously, the first power supply end of the operational amplifier circuit is connected with the power supply, and the second power supply end is connected with the voltage reduction circuit through the conversion circuit, can be powered directly by the power supply of the vehicle-mounted control system, need not set up the DC-DC converter and carry out voltage rise, reduced the circuit cost, also avoided the radiation interference brought by the DC-DC converter.

[0040] The above, only for the specific implementation of the utility model, but the protection scope of the utility model is not limited to this, any skilled in the art of the technology person in the utility model disclosed technical range, can easily think of various equivalent modifications or replacement, these modifications or replacement all should be covered in the protection scope of the utility model. Therefore, the protection scope of the utility model should be the protection scope of the claims.

Claims

1. An audio output circuit, characterized by comprising: The audio output circuit is applied to a vehicle control system, and comprises: an operational amplifier circuit, an input end of the operational amplifier circuit being connected with an audio control circuit of the vehicle control system, an output end of the operational amplifier circuit being connected with an audio device of the vehicle control system, and a first power supply end of the operational amplifier circuit being connected with a power supply of the vehicle control system; a conversion circuit, an input end of the conversion circuit being connected with a voltage reduction circuit of the vehicle control system, and an output end of the conversion circuit being connected with a second power supply end of the operational amplifier circuit.

2. The audio output circuit of claim 1, wherein, The operational amplifier circuit comprises a first operational amplifier circuit and a second operational amplifier circuit. The input end of the first operational amplifier circuit and the input end of the second operational amplifier circuit are both connected with the audio control circuit, and the output end of the first operational amplifier circuit and the output end of the second operational amplifier circuit are both connected with the audio device. The first power supply end of the first operational amplifier circuit and the first power supply end of the second operational amplifier circuit are both connected with the power supply. The second power supply end of the first operational amplifier circuit and the second power supply end of the second operational amplifier circuit are both connected with the conversion circuit.

3. The audio output circuit of claim 2, wherein, The first operational amplifier circuit comprises a first operational amplifier, a non-inverting input end of the first operational amplifier being connected with a reference end, an inverting input end of the first operational amplifier being connected with the audio control circuit, and an output end of the first operational amplifier being connected with the audio device. A positive pole of the first operational amplifier is connected with the power supply as the first power supply end, and a negative pole of the first operational amplifier is connected with the conversion circuit as the second power supply end.

4. The audio output circuit of claim 3, wherein, The first operational amplifier circuit further comprises a first resistor, a second resistor and a first capacitor. One end of the first resistor is connected with the audio control circuit, the other end of the first resistor is connected with one end of the first capacitor and one end of the second resistor respectively, the other end of the second resistor is connected with the inverting input end of the first operational amplifier, and the other end of the first capacitor is grounded.

5. The audio output circuit of claim 4, wherein, The first operational amplifier circuit further comprises a third resistor, a fourth resistor, a second capacitor and a third capacitor. One end of the third resistor is connected with the first resistor, the other end of the third resistor is connected with one end of the second capacitor and one end of the fourth resistor respectively, the other end of the second capacitor is connected with the inverting input end of the first operational amplifier, the other end of the fourth resistor is connected with one end of the third capacitor, and the other end of the third capacitor is connected with the audio device.

6. The audio output circuit of claim 2, wherein, The second operational amplifier circuit comprises a second operational amplifier, a non-inverting input end of the second operational amplifier being connected with a reference end, an inverting input end of the second operational amplifier being connected with the audio control circuit, and an output end of the second operational amplifier being connected with the audio device. A positive pole of the second operational amplifier is connected with the power supply as the first power supply end, and a negative pole of the second operational amplifier is connected with the conversion circuit as the second power supply end.

7. The audio output circuit of claim 6, wherein, The first operational amplifier circuit further comprises a fifth resistor, a sixth resistor and a fourth capacitor. One end of the fifth resistor is connected with the audio control circuit, the other end of the fifth resistor is connected with one end of the fourth capacitor and one end of the sixth resistor respectively, the other end of the sixth resistor is connected with the inverting input terminal of the second operational amplifier, the other end of the fourth capacitor is grounded.

8. The audio output circuit of claim 7, wherein, The first operational amplifier circuit further comprises a seventh resistor, an eighth resistor, a fifth capacitor and a sixth capacitor; One end of the seventh resistor is connected with the fifth resistor, the other end of the seventh resistor is connected with one end of the fifth capacitor and one end of the eighth resistor respectively, the other end of the fifth capacitor is connected with the inverting input terminal of the second operational amplifier, the other end of the eighth resistor is connected with one end of the sixth capacitor, the other end of the sixth capacitor is connected with the audio device.

9. The audio output circuit of claim 1, wherein, The conversion circuit comprises a seventh capacitor, an eighth capacitor, a ninth capacitor, a first diode, a second diode and a first inductor; One end of the seventh capacitor is connected with the voltage reduction circuit, the other end of the seventh capacitor is connected with the negative electrode of the first diode and the negative electrode of the second diode respectively, the positive electrode of the first diode is grounded, the positive electrode of the second diode is connected with one end of the eighth capacitor, one end of the ninth capacitor and one end of the first inductor respectively, the other end of the eighth capacitor and the other end of the ninth capacitor are both grounded, the other end of the first inductor is connected with the second power supply terminal of the operational amplifier circuit.

10. An in-vehicle control system characterized by comprising: The vehicle-mounted control system comprises an audio control circuit, an audio device, a power supply, a voltage reduction circuit and the audio output circuit according to any one of claims 1-9.

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