AUX input circuit and audio playback system

Abstract

The embodiment of the present application belongs to the field of audio processing technology and relates to an AUX input circuit, comprising: an interface module, a receiving module, a control module and an output module; the interface module is connected to the receiving module and transmits peripheral signals to the receiving module, the peripheral signals including power signals and audio signals; the receiving module is used to receive the peripheral signals; the control module is connected to the receiving module and is used to turn off the output function of the output module when the power signal is abnormal; the output module is connected to the control module and is used to transmit the audio signal to the power amplifier circuit when the power signal is normal. The present application also relates to an audio playback system. The technical solution provided by the present application can avoid the generation of noise.

Description

Technical Field

[0001] The present application relates to the field of audio processing technology, and more specifically, to an AUX input circuit and an audio playback system. Background Art

[0002] Many audio electronics feature an AUX (auxiliary) input. AUX is an additional signal line. During use, actions such as plugging and unplugging AUX cables, or shutting down or losing power to AUX peripherals often occur. Abnormal signals generated during these processes can be transmitted to the playback device through the AUX cable, causing varying degrees of noise.

[0003] Low-end electronic products often overlook this issue due to manufacturing costs. High-end products often use dedicated chips with power-off detection. When the device is turned off or the power goes out, the chip detects that the power supply voltage has fallen below a set value and automatically shuts off the signal output, preventing noise from the subsequent amplifiers. However, chip detection increases manufacturing costs and doesn't address the noise generated when plugging and unplugging the AUX signal cable. Summary of the Invention

[0004] The technical problem to be solved by the embodiments of the present application is to solve the problem that devices with AUX input interfaces generate abnormal signals and cause noise during use due to actions such as plugging and unplugging, shutting down, and powering off the AUX peripherals.

[0005] In order to solve the above technical problems, the embodiment of the present application provides an AUX input circuit, which adopts the following technical solution:

[0006] Interface module, receiving module, control module and output module;

[0007] The interface module is connected to the receiving module and sends the signal transmitted by the peripheral device to the receiving module, wherein the signal includes a power signal and an audio signal;

[0008] The receiving module is used to receive the signal;

[0009] The control module is connected to the receiving module and is used to

[0010] When the power signal is abnormal, turning off the output function of the output module;

[0011] The output module is connected to the control module and is used to transmit the audio signal to the power amplifier circuit when the power signal is normal.

[0012] Furthermore, the interface module is provided with a power supply voltage branch and a channel branch, the power supply voltage branch and the channel branch are electrically connected to the receiving module, the power supply voltage branch is used to transmit the power signal, and the channel branch is used to transmit the audio signal.

[0013] Furthermore, the interface module further includes a grounding branch, and the grounding branch is grounded.

[0014] Furthermore, the receiving module includes a voltage dividing unit, and the voltage dividing unit is connected to the interface module and the control module.

[0015] Furthermore, the voltage dividing unit includes a voltage-stabilizing diode, a first resistor, and a second resistor; the cathode of the voltage-stabilizing diode is connected to the interface module, and the anode of the voltage-stabilizing diode is connected to one end of the first resistor;

[0016] One end of the second resistor is connected to the other end of the first resistor, and the other end of the second resistor is grounded.

[0017] Furthermore, the receiving module further includes a filtering unit, which is connected to the voltage dividing unit and is used to filter out interference signals in the circuit.

[0018] Furthermore, the filtering unit includes a capacitor, one end of the capacitor is connected to a common end of the first resistor and the second resistor, and the other end of the capacitor is grounded.

[0019] Furthermore, the control module includes a power supply unit and a control unit, wherein the power supply unit is connected to the control unit for providing working power for the circuit; the control unit is connected to the receiving module and the output module for controlling the output function of the output module.

[0020] Furthermore, the control unit includes a first transistor, a second transistor, a third resistor, and a fourth resistor; the base of the first transistor is connected to the other end of the first resistor, the emitter of the first transistor is grounded, and the collector of the first transistor is connected to one end of the third resistor and the base of the second transistor respectively;

[0021] The collector of the second transistor is connected to one end of the fourth resistor and the output module respectively, and the emitter of the second transistor is grounded;

[0022] The other end of the third resistor is connected to the power supply unit, and the other end of the fourth resistor is connected to the power supply unit.

[0023] In order to solve the above technical problems, the embodiment of the present application further provides an audio playback system, which adopts the following technical solution:

[0024] The audio playback system includes a processing device and a playback device, and the processing device and the playback device are electrically connected;

[0025] The processing device includes a power amplifier circuit and the AUX input circuit as described above, and the power amplifier circuit is connected to the output module in the AUX input circuit;

[0026] The playing device is connected to the power amplifier circuit and is used to play the audio signal.

[0027] Compared with the prior art, the embodiments of the present application have the following beneficial effects:

[0028] The present application provides an AUX input circuit, including: an interface module, a receiving module, a control module and an output module. The interface module is connected to the receiving module and transmits peripheral signals to the receiving module. The peripheral signals include power signals and audio signals. The receiving module is used to receive peripheral signals. The control module is connected to the receiving module and is used to turn off the output function of the output module when the power signal is abnormal. The output module is connected to the control module and is used to transmit the audio signal to the power amplifier circuit when the power signal is normal. The present application controls the output function of the output module to be turned off when the power signal received by the receiving module is abnormal. By turning off the output function of the output module, the audio signal cannot be transmitted to the back-end circuit through the output module, thereby avoiding the generation of noise. In addition, the noise can be eliminated directly through circuit design, which can reduce manufacturing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the solutions in this application, a brief introduction will be given below to the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of this application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0030] Figure 1 This is a structural diagram of an AUX input circuit according to an embodiment of the present application. DETAILED DESCRIPTION

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meanings as commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of the application are only for the purpose of describing specific embodiments and are not intended to limit this application. The terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusions. The terms "first", "second", etc. in the specification and claims of this application or the above-mentioned drawings are used to distinguish different objects, not to describe a specific order.

[0032] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0033] The present application embodiment provides an AUX input circuit, see Figure 1 As shown, the circuit includes an interface module 1, a receiving module 2, a control module 3 and an output module 4; the interface module 1 is connected to the receiving module 2 and transmits peripheral signals to the receiving module 2, and the peripheral signals include power signals and audio signals; the receiving module 2 is used to receive peripheral signals; the control module 3 is connected to the receiving module 2 and is used to turn off the output function of the output module 4 when the power signal is abnormal; the output module 4 is connected to the control module 3 and is used to transmit the audio signal to the power amplifier circuit when the power signal is normal.

[0034] In some optional implementations of this embodiment, the interface module 1 is provided with a power supply voltage branch and a channel branch, which are electrically connected to the receiving module 2, the power supply voltage branch is used to transmit the power supply signal, and the channel branch is used to transmit the audio signal.

[0035] It should be noted that the channel branches include a left channel branch and a right channel branch. In addition, the interface module 1 is further provided with a grounding branch, which is grounded.

[0036] Specifically, the interface module is Figure 1 The interface J101 shown is a 4-pin signal line. The power supply voltage branch, the left channel branch, the right channel branch and the ground branch constitute the 4-pin signal line. The power supply voltage branch is used to transmit the power signal of the peripheral device. The left channel branch and the right channel branch transmit the left and right channel audio signals of the peripheral device respectively. The ground branch is connected to the reference ground.

[0037] See also Figure 1 As shown, the power supply voltage branch is lead 4, the right channel branch is lead 5 and lead 6, the left channel branch is lead 3 and lead 2, and the ground branch is lead 1.

[0038] In a specific implementation of this embodiment, two leads are respectively provided for the left channel branch and the right channel branch to transmit audio signals, which can improve the stability of signal transmission.

[0039] Interface module 1 is the interface of the playback device, which can be called an internal interface. The internal interface is connected to the external interface to transmit the external device signal to the playback device. The external device includes but is not limited to mobile phones, tablets, laptops, MP3 devices, etc., which can be connected to the playback device via a cable.

[0040] In this embodiment, the peripheral interface is an interface on the connecting line that is directly connected to the internal interface. Corresponding to the setting of the internal interface, the peripheral interface is also a 4-pin signal line. The power supply voltage branch, the left channel branch, the right channel branch and the ground branch constitute the 4-pin signal line. The power supply voltage branch is used to transmit the power signal of the peripheral to the input circuit; the left channel branch and the right channel branch respectively transmit the left and right channel audio signals of the peripheral to the playback device to realize the playback function; the ground branch is connected to the reference ground.

[0041] The receiving module 2 includes a voltage dividing unit, which is connected to the interface module 1 and the control module 3 .

[0042] Specifically, the voltage divider unit includes a Zener diode D100, a first resistor R100 and a second resistor R101. The cathode of the Zener diode D100 is connected to the interface module 1, and the anode of the Zener diode D100 is connected to one end of the first resistor R100; one end of the second resistor R101 is connected to the other end of the first resistor R100, and the other end of the second resistor R101 is grounded.

[0043] It should be noted that the function of the Zener diode is to maintain voltage stability. When the power supply voltage fluctuates or other reasons cause the voltage at various points in the circuit to change, the Zener diode can keep the voltage across the load basically unchanged, thereby protecting the electronic components in the circuit and preventing them from being broken down by high current.

[0044] As a specific implementation method, end 1 of the Zener diode D100 is the positive electrode and end 2 is the negative electrode. The negative electrode of the Zener diode D100 is connected to the power supply voltage branch of the interface J101. The positive electrode of the Zener diode D100 is connected in series with the first resistor R100 and the second resistor R101 in sequence. One end of R101 is grounded. The power signal of the peripheral is transmitted to the AUX input circuit and is divided by the Zener diode D100, the first resistor R100 and the second resistor R101.

[0045] The receiving module 2 further includes a filtering unit connected to the voltage dividing unit. The filtering unit is used to filter out interference signals in the circuit, prevent signal interference, and ensure the stability of the circuit operation.

[0046] In this embodiment, the filter unit includes a capacitor C383 connected in parallel with the second resistor R101. Specifically, one end of the capacitor C383 is connected to the common end of the first resistor R100 and the second resistor R101, and the other end of the capacitor C383 is grounded.

[0047] The control module 3 includes a power supply unit and a control unit, which are connected to the control unit. The power supply unit is used to provide operating voltage for the circuit. The control unit is connected to the receiving module 1 and the output module 4 and is used to control the output function of the output module 4. Specifically, when the power signal is normal, the output module 4 is turned on, and when the power signal is abnormal, the output module 4 is turned off.

[0048] It should be noted that the power supply unit can be set inside the circuit or powered by an external power supply. The specific power supply method is not limited in this embodiment and can be set according to actual needs.

[0049] A normal power signal means that the signal voltage of the peripheral input signal is transmitted stably and the signal voltage reaches the circuit's conduction voltage. An abnormal power signal means that when the peripheral is suddenly shut down, powered off, or the connection cable is unplugged, the signal voltage decays rapidly and falls below the circuit's conduction voltage.

[0050] In this embodiment, the control unit includes a first transistor Q100, a second transistor Q101, a third resistor R102 and a fourth resistor R103. The base of the first transistor Q100 is connected to the other end of the first resistor, the emitter of the first transistor Q100 is grounded, and the collector of the first transistor Q100 is respectively connected to one end of the third resistor R102 and the base of the second transistor Q101; the collector of the second transistor Q101 is respectively connected to one end of the fourth resistor R103 and the output module 4, and the emitter of the second transistor Q101 is grounded; the other end of the third resistor R102 is connected to the power supply unit, and the other end of the fourth resistor R103 is connected to the power supply unit.

[0051] It should be noted that the power signal transmitted by the power voltage branch is used to determine whether to turn on or off the output function of the control output module, and the power supply unit provides the power voltage for the circuit to work.

[0052] It should be understood that the resistance values ​​of the first resistor, the second resistor, the third resistor and the fourth resistor can be set according to actual conditions.

[0053] See also Figure 1 As shown, the power supply unit is VCC, for example, the power supply voltage is 3.3V; the output module 4 is SIGNAL_OUTPUT.

[0054] As a specific example, terminal 1 of the first transistor Q100 is the emitter E, terminal 2 is the base B, and terminal 3 is the collector C. Terminal 1 of the second transistor Q101 is the emitter E, terminal 2 is the base B, and terminal 3 is the collector C. Both the first transistor Q100 and the second transistor Q101 are NPN transistors. Current flows in two directions in an NPN transistor: one is the base current flowing from the base B to the emitter E, and the other is the collector current flowing from the collector C to the emitter E.

[0055] The transistor has three working states, namely saturation conduction, cutoff state and amplification state. When the voltage of the BE pole is greater than a certain voltage value, the transistor is in saturation conduction state; when the voltage of the BE pole is less than or equal to a certain voltage value, the transistor is in cutoff state. When the emitter junction BE of the transistor is forward biased and the collector junction BC is reverse biased, the transistor will enter the amplification state. In the amplification state, there will be a certain voltage drop between the collector C and the emitter B. As for the voltage drop U CE How big it is depends on the specific circuit.

[0056] In a specific implementation, when the voltage of the BE pole is greater than 0.7V, the transistor is in a saturated conduction state; when the voltage of the BE pole is less than or equal to 0.7V, the transistor is in a cut-off state.

[0057] The BE terminal of the first triode Q100 is connected in parallel with the second resistor R101, and the voltage at the BE terminal is equal to the voltage of R101. During normal operation, a 24V power signal from the peripheral device is transmitted to the playback device. When the playback device receives the power signal, after voltage division by the Zener diode D100, the first resistor R100, and the second resistor R101, the voltage at the BE terminal of the first triode Q100 exceeds 0.7V. The first triode Q100 is in a saturated conduction state, with a straight line connection between the CE terminals. The voltage between the emitter E and collector C of Q100 is 0, and the voltage at the base B of the second triode Q101 is also 0, making the voltage at the BE terminal less than or equal to 0.7V, and Q101 is in the off state.

[0058] When the second transistor Q101 is in the cut-off state, the impedance between the CE poles is infinite and is in the disconnected state. The power supply voltage of the power supply unit outputs a high level through the fourth resistor R103. The output module 4 is connected to the enable port of the power amplifier of the playback device. When the enable port detects a high level, the output function of the output module 4 is controlled to be turned on, and the audio signal is transmitted to the back-end power amplifier circuit, and then transmitted to the playback device, such as a speaker, through the power amplifier circuit to complete the normal audio playback function.

[0059] When a peripheral device is suddenly shut down, loses power, or has its signal line unplugged, a noise signal is generated and transmitted to the playback device via the AUX line. At the same time, the voltage of the peripheral device's power signal will rapidly decay due to such events. A Zener diode needs to reach a certain voltage value to conduct. When the voltage value of the power signal decays below a certain voltage value, the power signal cannot be divided by the Zener diode D100, the first resistor R100, and the second resistor R101, causing the first transistor Q100 to be in the cut-off state. Specifically, the Zener diode has a conduction voltage of 20V. When the voltage value of the power signal decays below 20V, it cannot be divided by the Zener diode D100, the first resistor R100, and the second resistor R101.

[0060] When the first transistor Q100 is in the cut-off state, the supply voltage of the power supply unit is divided by the third resistor R102 and transmitted to the second transistor Q101. The second transistor Q101 is in a saturated conduction state, and the CE poles are in a straight-line connection state. The voltage between the emitter E and the collector C of Q101 is 0. The output module 4 outputs a low level due to the saturated conduction of Q101. When the enable port detects a low level, the output function of the control output module 4 is turned off, and the audio signal cannot be transmitted to the back-end power amplifier circuit, thereby realizing the noise elimination function.

[0061] The present application controls the output function of the output module according to the power signal received by the receiving module through the control module, controls the turning on or off of the output function, and turns off the output function of the output module when the power signal is abnormal, so that the audio signal cannot be transmitted to the back-end circuit through the output module, thereby avoiding the generation of noise. At the same time, the noise can be eliminated directly through circuit design, which can reduce manufacturing costs.

[0062] The present application also provides an audio playback system, which includes a processing device and a playback device, the processing device and the playback device are electrically connected, the processing device is also provided with a power amplifier circuit and an AUX input circuit as in the above embodiment, the power amplifier circuit is connected to the output module 4 of the AUX input circuit; the playback device is connected to the power amplifier circuit for playing audio signals.

[0063] Obviously, the embodiments described above are only some of the embodiments of the present application, rather than all of the embodiments. The preferred embodiments of the present application are given in the accompanying drawings, but they do not limit the patent scope of the present application. The present application can be implemented in many different forms. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present application more thorough and comprehensive. Although the present application has been described in detail with reference to the aforementioned embodiments, for those skilled in the art, it is still possible to modify the technical solutions described in the aforementioned specific embodiments, or to make equivalent replacements for some of the technical features therein. Any equivalent structure made using the contents of the present application specification and the accompanying drawings, directly or indirectly used in other related technical fields, is also within the scope of patent protection of the present application.

Claims

1. An AUX input circuit, characterized in that: include: Interface module, receiving module, control module and output module; The interface module is connected to the receiving module and transmits the peripheral signal to the receiving module, wherein the peripheral signal includes a power signal and an audio signal; The receiving module is used to receive the peripheral signal; The control module is connected to the receiving module and is used to turn off the output function of the output module when the power signal is abnormal, and turn on the output function of the output module when the power signal is normal; The output module is connected to the control module and is used to transmit the audio signal to the power amplifier circuit when the power signal is normal; The control module includes a power supply unit and a control unit. The power supply unit is connected to the control unit and is used to provide working power for the circuit. The control unit is connected to the receiving module and the output module and is used to control the output function of the output module. The control unit includes a first transistor, a second transistor, a third resistor, and a fourth resistor; the base of the first transistor is connected to the other end of the first resistor, the emitter of the first transistor is grounded, and the collector of the first transistor is connected to one end of the third resistor and the base of the second transistor respectively; The collector of the second transistor is connected to one end of the fourth resistor and the output module respectively, and the emitter of the second transistor is grounded; The other end of the third resistor is connected to the power supply unit, and the other end of the fourth resistor is connected to the power supply unit; Among them, when the power supply signal is normal, the power supply unit outputs a high level to the output module through the fourth resistor, controlling the output function of the output module to be turned on; when the power supply signal is abnormal, the second transistor is in a saturated conduction state, outputs a low level to the output module, and controls the output function of the output module to be turned off.

2. The AUX input circuit according to claim 1, wherein: The interface module is provided with a power supply voltage branch and a sound channel branch, the power supply voltage branch and the sound channel branch are electrically connected to the receiving module, the power supply voltage branch is used to transmit the power signal, and the sound channel branch is used to transmit the audio signal.

3. The AUX input circuit according to claim 2, wherein: The interface module further includes a grounding branch, which is grounded.

4. The AUX input circuit according to claim 1, wherein: The receiving module includes a voltage dividing unit, and the voltage dividing unit is connected to the interface module and the control module.

5. The AUX input circuit according to claim 4, characterized in that: The voltage dividing unit includes a voltage-stabilizing diode, a first resistor, and a second resistor; the cathode of the voltage-stabilizing diode is connected to the interface module, and the anode of the voltage-stabilizing diode is connected to one end of the first resistor; One end of the second resistor is connected to the other end of the first resistor, and the other end of the second resistor is grounded.

6. The AUX input circuit according to claim 5, characterized in that: The receiving module further includes a filtering unit, which is connected to the voltage dividing unit and is used to filter out interference signals in the circuit.

7. The AUX input circuit according to claim 6, wherein: The filtering unit includes a capacitor, one end of the capacitor is connected to a common end of the first resistor and the second resistor, and the other end of the capacitor is grounded.

8. An audio playback system comprising a processing device and a playback device, wherein the processing device and the playback device are electrically connected, and wherein: The processing device comprises a power amplifier circuit and the AUX input circuit according to any one of claims 1 to 7, wherein the power amplifier circuit is connected to the output module in the AUX input circuit; The playing device is connected to the power amplifier circuit and is used to play the audio signal.

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