An audio return circuit and an audio separator

Abstract

The utility model relates to audio frequency processing technical field, concretely relates to an audio frequency backhaul circuit and audio frequency separator. The audio frequency backhaul circuit includes HDMI interface, audio output interface, inverting module and main control chip, and main control chip is connected with HDMI interface, and main control chip is used to communicate with external equipment through HDMI interface, and controls HDMI interface to receive ARC signal, and HDMI interface is used to transmit the ARC signal received to inverting module, and inverting module is used to convert ARC signal into SPDIF signal, and exports SPDIF signal through audio output interface. In the application, the inverting module replaces the logic circuit in the main control chip to realize the audio frequency backhaul, and the chip with the audio frequency backhaul function is not needed to be used as the main control chip, the ordinary main control chip with lower cost is allowed to realize the audio frequency backhaul, the audio frequency backhaul circuit and the audio frequency separator applied are lower in overall cost, and the main control chip has more selectivity.

Description

Technical Field

[0001] This utility model relates to the field of audio processing technology, and in particular to an audio return circuit and an audio splitter. Background Technology

[0002] Audio Return Channel (ARC) circuitry enables the reverse transmission of audio signals from the display back to the audio playback device (such as speakers, amplifiers, etc.) in products such as audio splitters and HDMI switchers, significantly reducing device cabling.

[0003] In related audio return circuits, audio return is usually implemented using the logic circuits inside the main control chip. Chips with audio return (ARC) functionality are required to enable the audio return function of the applied products. This results in limited options for audio return circuits and the main control chips used in the applied products, and the overall cost is high. Utility Model Content

[0004] This utility model provides an audio return circuit and an audio splitter to solve the problems of limited main control chip options and high overall cost in audio return circuits.

[0005] This utility model discloses an audio return circuit, including an HDMI interface, an audio output interface, an inverter module, and a main control chip. The main control chip is connected to the HDMI interface and is used to communicate with external devices through the HDMI interface and control the HDMI interface to receive ARC signals. The HDMI interface is used to transmit the received ARC signals to the inverter module, and the inverter module is used to convert the ARC signals into SPDIF signals and output the SPDIF signals through the audio output interface.

[0006] Optionally, the inverter module includes an inverter chip and a coupling capacitor. The inverter chip has a first inverting channel and a second inverting channel. One end of the coupling capacitor is connected to the HDMI interface to receive the ARC signal, and the other end is connected to the input terminal of the first inverting channel. The output terminal of the first inverting channel is connected to the input terminal of the second inverting channel, and the output terminal of the second inverting channel is connected to the audio output interface.

[0007] Optionally, the inverting module further includes an adjustment unit for adjusting the feedback signal, the adjustment unit being connected to the input terminal of the first inverting channel and the input terminal of the second inverting channel.

[0008] Optionally, the adjustment unit includes a first resistor and a second resistor, the first resistor and the second resistor are connected in series and the series node is connected to the input terminal of the second inverting channel, the other end of the first resistor is connected to the input terminal of the first inverting channel, and the other end of the second resistor is connected to ground.

[0009] Optionally, the audio return circuit further includes a signal pull-up module, which is connected to the CEC communication terminal of the main control chip, the CEC communication terminal of the HDMI interface, and an external power supply.

[0010] Optionally, the signal pull-up module includes a third resistor, a fourth resistor, a fifth resistor, and a Zener diode. The third resistor and the fifth resistor are connected in series, and their series connection point is connected to one end of the fourth resistor. The other end of the third resistor is connected to the CEC communication terminal of the main control chip. The other end of the fourth resistor is connected to the CEC communication terminal of the HDMI interface. The other end of the fifth resistor is connected to the negative terminal of the Zener diode. The positive terminal of the Zener diode is connected to an external power supply.

[0011] Optionally, the audio feedback circuit further includes a power supply interface module connected to the power supply interface and a voltage regulator module, which is used to supply power to the main control chip and the inverting module.

[0012] Optionally, the power supply interface module includes a Type-C interface, an anti-backflow diode, a transient suppression diode, a fuse, and a sixth resistor. The fuse is connected in series with the anti-backflow diode. The negative terminal of the anti-backflow diode is connected to the voltage input terminal of the voltage regulator module. The other end of the fuse is connected to the power supply terminal of the Type-C interface. One end of the transient suppression diode is connected to the series node of the fuse and the anti-backflow diode, and the other end is connected to ground. One end of the sixth resistor is connected to the voltage input terminal of the voltage regulator module, and the other end is connected to ground.

[0013] Optionally, the audio return circuit further includes an electrostatic discharge (ESD) protection module, which includes a first ESD protection tube, a second ESD protection tube, and a third ESD protection tube. The negative terminal of the first ESD protection tube is connected to the data communication terminal of the HDMI interface, the negative terminal of the second ESD protection tube is connected to the clock signal terminal of the HDMI interface, and the negative terminal of the third ESD protection tube is connected to the hot-plug detection terminal of the HDMI interface. The positive terminals of the first ESD protection tube, the second ESD protection tube, and the third ESD protection tube are all connected to ground.

[0014] This utility model also discloses an audio splitter, including the audio return circuit as described in any of the above claims.

[0015] The beneficial effects of the audio return circuit and audio splitter provided in this embodiment of the present invention are as follows: By setting up an HDMI interface, an audio output interface, an inverting module, and a main control chip, the main control chip communicates with external devices through the HDMI interface. The HDMI interface can receive the ARC signal transmitted by the device, and the inverting module converts the ARC signal into an SPDIF signal. The converted SPDIF signal is then output to the connected audio playback device through the audio output interface, thereby realizing the audio return function. Therefore, in this application, the inverting module replaces the internal logic circuit of the main control chip to realize audio return, eliminating the need to use a chip with audio return function as the main control chip. This allows for the use of a low-cost ordinary main control chip to realize audio return. The overall cost of the audio return circuit and the applied audio splitter is low, and there are many options for the main control chip. Attached Figure Description

[0016] The technical solution of this utility model will be further described in detail below with reference to the accompanying drawings and embodiments. In the accompanying drawings: Figure 1 This is a structural block diagram of the audio return circuit according to an embodiment of the present invention; Figure 2 This is a circuit diagram of the HDMI interface according to an embodiment of the present utility model; Figure 3 This is a circuit diagram of the inverting module according to an embodiment of the present invention; Figure 4 This is a circuit diagram of the main control chip in an embodiment of the present invention; Figure 5 This is a circuit diagram of the audio output interface according to an embodiment of the present invention; Figure 6 This is a circuit diagram of the signal pull-up module according to an embodiment of the present invention; Figure 7 This is a circuit diagram of the power supply interface module according to an embodiment of the present utility model; Figure 8 This is a circuit diagram of the voltage regulator module according to an embodiment of the present invention.

[0017] The labels for the attached figures are as follows: 10. HDMI interface; 20. Audio output interface; 30. Inverter module; 31. Adjustment unit; 40. Signal pull-up module; 50. Power supply interface module; 60. Voltage regulator module; 70. Electrostatic discharge (ESD) protection module; U1. Main control chip; U2. Inverter chip; C1. Coupling capacitor; R1. First resistor; R2. Second resistor; R3. Third resistor; R4. Fourth resistor; R5. Fifth resistor; R6. Sixth resistor; D1. Zener diode; D2. Anti-reverse current diode; D3. Transient voltage suppressor diode; D4. First ESD protection diode; D5. Second ESD protection diode; D6. Third ESD protection diode; J1. Type-C interface; F1. Fuse; U3. Voltage regulator chip; C2. First filter capacitor; C3. Second filter capacitor; C4. Third filter capacitor; C5. Fourth filter capacitor. Detailed Implementation

[0018] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The preferred embodiments of this utility model will now be described in detail with reference to the accompanying drawings.

[0019] This utility model embodiment provides an audio return circuit, such as Figures 1 to 5 As shown, the audio return circuit includes an HDMI interface 10, an audio output interface 20, an inverter module 30, and a main control chip U1. The main control chip U1 is connected to the HDMI interface 10. The main control chip U1 is used to communicate with external devices through the HDMI interface 10 and control the HDMI interface 10 to receive ARC signals. The HDMI interface 10 is used to transmit the received ARC signals to the inverter module 30. The inverter module 30 is used to convert the ARC signals into SPDIF signals and output the SPDIF signals through the audio output interface 20.

[0020] The audio return circuit of this application embodiment is configured with an HDMI interface 10, an audio output interface 20, an inverter module 30, and a main control chip U1. The main control chip U1 communicates with external devices through the HDMI interface 10. The HDMI interface 10 can receive the ARC signal transmitted by the device, and the inverter module 30 converts the ARC signal into an SPDIF signal. The converted SPDIF signal is output to the connected audio playback device through the audio output interface 20, thereby realizing the audio return function. Therefore, in this application, the inverter module 30 replaces the internal logic circuit of the main control chip U1 to realize audio return, eliminating the need to use a chip with audio return function as the main control chip U1. This allows the use of a lower-cost ordinary main control chip U1 to realize audio return, resulting in a lower overall cost and more options for the main control chip U1.

[0021] ARC is an abbreviation for "Audio Return Channel." It's not a specific audio format itself, but rather a "channel" that carries audio signals. Audio signals transmitted through this channel may be in common formats such as Dolby or DTS. SPDIF signals are a standard signal used to transmit digital audio; they transmit undecoded digital audio signals.

[0022] The main control chip U1 communicates with external devices through the HDMI interface 10. Specifically, the main control chip U1 interacts with external devices through the HDMI interface 10 to exchange CEC signals and reads the EDID (Extended display identification data) information of the connected device through the HDMI interface 10.

[0023] In an optional embodiment of this application, reference is made to Figures 1 to 3 The inverter module 30 includes an inverter chip U2 and a coupling capacitor C1. The inverter chip U2 has a first inverting channel and a second inverting channel. One end of the coupling capacitor C1 is connected to the HDMI interface 10 to receive ARC signals, and the other end is connected to the input terminal A1 of the first inverting channel. The output terminal Y1 of the first inverting channel is connected to the input terminal A2 of the second inverting channel, and the output terminal Y2 of the second inverting channel is connected to the audio output interface 20.

[0024] Specifically, the ARC signal received by the HDMI interface 10 is coupled to the inverter module 30 via coupling capacitor C1. Coupling capacitor C1 isolates the DC component, preventing DC from affecting the subsequent inverter chip U2. The coupled ARC signal is input to the first inverting channel of the inverter chip U2. After being inverted and shaped, the ARC signal is output to the second inverting channel for further inversion and shaping, converting it into an SPDIF signal. Finally, it is output to an external audio playback device through the audio output interface 20 for playback. Compared to the dedicated ARC function main control chip U1, the inverter chip U2 has a lower cost. Furthermore, the circuit structure of the inverter module 30 is simple. Optionally, the inverter chip U2 can use a chip such as SN74LVC2G04.

[0025] Further reference Figures 1 to 3 The inverting module 30 also includes an adjustment unit 31 for adjusting the feedback signal. The adjustment unit 31 is connected to the input terminal A1 of the first inverting channel and the input terminal A2 of the second inverting channel.

[0026] By setting the adjustment unit 31, the input signal parameters (such as amplitude and phase) of the first and second inverting channels can be adjusted through the feedback mechanism to adapt to the differences in ARC signals transmitted by different external devices, ensure that the converted SPDIF signal meets the standard, and improve the adaptability of the circuit.

[0027] Optional, see reference Figures 1 to 3 The adjustment unit 31 includes a first resistor R1 and a second resistor R2. The first resistor R1 and the second resistor R2 are connected in series, with the series connection point connected to the input terminal A2 of the second inverting channel. The other end of the first resistor R1 is connected to the input terminal A1 of the first inverting channel, and the other end of the second resistor R2 is connected to ground. By setting the first resistor R1 and the second resistor R2 to form a voltage divider feedback network, adjusting the resistance values ​​of the first resistor R1 and the second resistor R2 can control the signal amplitude output to the second inverting channel, avoiding excessively strong or weak output SPDIF signals due to fluctuations in ARC signal strength, and ensuring that the signal meets the standard. The voltage divider feedback can also suppress signal drift caused by power fluctuations in the two inverting channels, making the inverter chip U2 more stable, reducing signal distortion, and improving the stability of the inverting module 30.

[0028] In other embodiments, the adjustment unit 31 may be connected in series with three, four or more resistors to form a voltage divider feedback network, which can also realize feedback adjustment of the inverter chip U2 signal. In this embodiment, the adjustment unit 31 is composed of a first resistor R1 and a second resistor R2, which has a relatively simple circuit and relatively low cost.

[0029] In an optional embodiment of this application, reference is made to Figure 1 , Figure 2 , Figure 4 and Figure 6 The audio feedback circuit also includes a signal pull-up module 40, which connects to the CEC communication terminal PC6 / AIN0 of the main control chip U1, the CEC communication terminal CE Remote of the HDMI interface 10, and an external power supply. In this way, the signal pull-up module 40 can pull the CEC signal, which ensures communication between the main control chip U1 and external devices via the HDMI interface 10, to a stable high level, preventing signal level drift caused by line impedance or interference, and ensuring accurate recognition of CEC commands (such as device control and status feedback) between the main control chip U1 and the HDMI interface 10.

[0030] Optional, see reference Figure 1 , Figure 2 , Figure 4 and Figure 6 The signal pull-up module 40 includes a third resistor R3, a fourth resistor R4, a fifth resistor R5, and a Zener diode D1. The third resistor R3 and the fifth resistor R5 are connected in series, and their series connection point is connected to one end of the fourth resistor R4. The other end of the third resistor R3 is connected to the CEC communication terminal PC6 / AIN0 of the main control chip U1. The other end of the fourth resistor R4 is connected to the CEC communication terminal CE Remote of the HDMI interface 10. The other end of the fifth resistor R5 is connected to the negative terminal of the Zener diode D1, and the positive terminal of the Zener diode D1 is connected to an external power supply.

[0031] The third resistor R3, the fourth resistor R4, and the fifth resistor R5 pull up the CEC communication terminal PC6 / AIN0 of the main control chip U1 and the CEC communication terminal CE Remote of the HDMI interface 10 to a high level potential of the external power supply. This prevents signal level drift caused by line impedance or interference, ensuring accurate recognition of CEC commands (such as device control and status feedback) between the main control chip U1 and the HDMI interface 10. The Zener diode D1 stabilizes the pull-up voltage within a suitable range, preventing the pull-up level from exceeding the tolerance threshold of the CEC terminals of the main control chip U1 and the HDMI interface when the external power supply voltage is too high, thus providing voltage limiting protection.

[0032] In an optional embodiment of this application, reference is made to Figure 1 The audio feedback circuit also includes a power supply interface module 50 and a voltage regulator module 60 connected to the power supply interface. The voltage regulator module 60 is used to supply power to the main control chip U1 and the inverting module 30.

[0033] Specifically, the power supply interface module 50 can be connected to an external power supply device to obtain power supply voltage. Since the externally input power supply voltage may fluctuate, the voltage regulator module 60 can stabilize the power supply voltage input to the power supply interface module 50 at the rated voltage required by the main control chip U1 and the inverter module 30, preventing voltage fluctuations from causing abnormal chip operation and improving the stability of the circuit operation.

[0034] Optional, see reference Figures 1 to 7 The power supply interface module 50 includes a Type-C interface J1, an anti-backflow diode D2, a transient suppression diode D3, a fuse F1, and a sixth resistor R6. The fuse F1 is connected in series with the anti-backflow diode D2. The negative terminal of the anti-backflow diode D2 is connected to the voltage input terminal of the voltage regulator module 60. The other end of the fuse F1 is connected to the power supply terminal of the Type-C interface J1. One end of the transient suppression diode D3 is connected to the series node of the fuse F1 and the anti-backflow diode D2, and the other end is connected to the ground terminal. One end of the sixth resistor R6 is connected to the voltage input terminal of the voltage regulator module 60, and the other end is connected to the ground terminal.

[0035] Specifically, the Type-C interface J1 serves as the external power input terminal, compatible with mainstream power adapters and improving interface versatility. The anti-backflow diode D2 prevents current from flowing back into the device connected to the Type-C interface J1, avoiding damage. The transient suppression diode D3 is connected in parallel between the power path and ground. In the event of a surge, lightning strike, or other instantaneous high voltage, it quickly breaks down and conducts, diverting the overvoltage to ground, protecting the downstream voltage regulator module 60, the inverter module 30 requiring power, and the main control chip U1. When a short circuit or overcurrent occurs, the fuse F1 will blow, cutting off the power supply and preventing continuous high current from burning out subsequent circuits. The sixth resistor, R6, acts as a pull-down resistor, stabilizing the voltage reference at the input of the voltage regulator module 60, preventing voltage fluctuations under no-load or light-load conditions, and assisting the voltage regulator module 60 in quickly entering a stable operating state.

[0036] Optional, see reference Figure 1 , Figure 4 , Figure 7 and Figure 8 The voltage regulator module 60 includes a voltage regulator chip U3, a first filter capacitor C2, a second filter capacitor C3, a third filter capacitor C4, and a fourth filter capacitor C5. The voltage input terminal of the voltage regulator chip U3 is connected to the power supply interface module 50, and the voltage output terminal is connected to the power supply terminals of the main control chip U1 and the inverting module 30. The first filter capacitor C2 and the second filter capacitor C3 are connected in parallel, and their first parallel node is connected to the voltage input terminal of the voltage regulator chip U3, and their second parallel node is connected to the ground terminal. The third filter capacitor C4 and the fourth filter capacitor C5 are connected in parallel, and their first parallel node is connected to the voltage output terminal of the voltage regulator chip U3, and their second parallel node is connected to the ground terminal.

[0037] Specifically, the voltage regulator chip U3 converts the unstable voltage input from the power supply interface module 50 into a stable rated voltage, providing the main control chip U1 and the inverter module 30 with a compliant operating power supply to ensure their stable operation. The first filter capacitor C2 and the second filter capacitor C3 are used to filter out high-frequency noise and ripple in the input voltage, preventing noise from affecting the voltage regulation accuracy of the voltage regulator chip U3 and ensuring the purity of the input voltage. The third filter capacitor C4 and the fourth filter capacitor C5 can filter out residual high-frequency noise after voltage regulation, stabilizing the output voltage and preventing voltage fluctuations from affecting the operation of subsequent circuits.

[0038] In an optional embodiment of this application, reference is made to Figure 1 and Figure 2The audio return circuit also includes an electrostatic discharge (ESD) protection module 70, which includes a first ESD protection diode D4, a second ESD protection diode D5, and a third ESD protection diode D6. The negative terminal of the first ESD protection diode D4 is connected to the data communication terminal DDC DATA of the HDMI interface 10, the negative terminal of the second ESD protection diode D5 is connected to the clock signal terminal DDC CLK of the HDMI interface 10, and the negative terminal of the third ESD protection diode D6 is connected to the hot-plug detection terminal HPD of the HDMI interface 10. The positive terminals of the first ESD protection diode D4, the second ESD protection diode D5, and the third ESD protection diode D6 are all connected to the ground terminal.

[0039] Specifically, the data communication terminal DDC DATA, clock signal terminal DDC CLK, and hot-plug detection terminal HPD of the HDMI interface 10 are the core ports for data transmission and device interaction, and are susceptible to electrostatic discharge (ESD) (such as static electricity from the human body when plugging and unplugging devices). The first ESD protection diode D4, the second ESD protection diode D5, and the third ESD protection diode D6 of the ESD protection module 70 will instantly conduct when encountering high voltage ESD, quickly discharging the ESD charge to ground through the positive terminal, limiting the voltage peak of the critical signal terminals within a safe range, and preventing ESD damage to the HDMI interface and related components such as the main control chip U1. Therefore, the first ESD protection diode D4, the second ESD protection diode D5, and the third ESD protection diode D6 respectively correspond to the data communication terminal DDC DATA, the clock signal terminal DDC CLK, and the hot-plug detection terminal HPD, forming directional protection to prevent ESD from damaging internal components of the interface or interfering with signal transmission.

[0040] The audio return circuit of this application embodiment can be applied to products such as audio splitters and video switchers to realize the audio return function of the products.

[0041] This embodiment of the invention also provides an audio splitter, which includes the audio return circuit as described above. This audio splitter has the same structure and beneficial effects as the audio return circuit in the foregoing embodiments. The structure and beneficial effects of the audio return circuit have been described in detail in the foregoing embodiments and will not be repeated here.

[0042] It should be understood that the above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Those skilled in the art can modify the technical solutions described in the above embodiments, or make equivalent substitutions for some of the technical features; and all such modifications and substitutions should fall within the protection scope of the appended claims of this utility model.

Claims

1. An audio return circuit, characterized in that, The device includes an HDMI interface, an audio output interface, an inverter module, and a main control chip. The main control chip is connected to the HDMI interface and is used to communicate with external devices through the HDMI interface and control the HDMI interface to receive ARC signals. The HDMI interface is used to transmit the received ARC signals to the inverter module, which is used to convert the ARC signals into SPDIF signals and output the SPDIF signals through the audio output interface.

2. The audio return circuit according to claim 1, characterized in that, The inverter module includes an inverter chip and a coupling capacitor. The inverter chip has a first inverting channel and a second inverting channel. One end of the coupling capacitor is connected to the HDMI interface to receive the ARC signal, and the other end is connected to the input terminal of the first inverting channel. The output terminal of the first inverting channel is connected to the input terminal of the second inverting channel, and the output terminal of the second inverting channel is connected to the audio output interface.

3. The audio return circuit according to claim 2, characterized in that, The inverting module also includes an adjustment unit for adjusting the feedback signal, the adjustment unit being connected to the input terminal of the first inverting channel and the input terminal of the second inverting channel.

4. The audio return circuit according to claim 3, characterized in that, The adjustment unit includes a first resistor and a second resistor. The first resistor and the second resistor are connected in series and the series node is connected to the input terminal of the second inverting channel. The other end of the first resistor is connected to the input terminal of the first inverting channel, and the other end of the second resistor is connected to ground.

5. The audio return circuit according to any one of claims 1-4, characterized in that, The audio return circuit also includes a signal pull-up module, which is connected to the CEC communication terminal of the main control chip, the CEC communication terminal of the HDMI interface, and an external power supply.

6. The audio return circuit according to claim 5, characterized in that, The signal pull-up module includes a third resistor, a fourth resistor, a fifth resistor, and a Zener diode. The third resistor and the fifth resistor are connected in series, and their series connection point is connected to one end of the fourth resistor. The other end of the third resistor is connected to the CEC communication terminal of the main control chip. The other end of the fourth resistor is connected to the CEC communication terminal of the HDMI interface. The other end of the fifth resistor is connected to the negative terminal of the Zener diode. The positive terminal of the Zener diode is connected to an external power supply.

7. The audio return circuit according to any one of claims 1-4, characterized in that, The audio feedback circuit also includes a power supply interface module connected to the power supply interface, and the power supply interface module is used to supply power to the main control chip and the inverting module.

8. The audio return circuit according to claim 7, characterized in that, The power supply interface module includes a Type-C interface, an anti-backflow diode, a transient suppression diode, a fuse, and a sixth resistor. The fuse is connected in series with the anti-backflow diode. The negative terminal of the anti-backflow diode is connected to the voltage input terminal of the voltage regulator module. The other end of the fuse is connected to the power supply terminal of the Type-C interface. One end of the transient suppression diode is connected to the series node of the fuse and the anti-backflow diode, and the other end is connected to ground. One end of the sixth resistor is connected to the voltage input terminal of the voltage regulator module, and the other end is connected to ground.

9. The audio return circuit according to any one of claims 1-4, characterized in that, The audio return circuit also includes an electrostatic discharge (ESD) protection module, which includes a first ESD protection tube, a second ESD protection tube, and a third ESD protection tube. The negative terminal of the first ESD protection tube is connected to the data communication terminal of the HDMI interface, the negative terminal of the second ESD protection tube is connected to the clock signal terminal of the HDMI interface, and the negative terminal of the third ESD protection tube is connected to the hot-plug detection terminal of the HDMI interface. The positive terminals of the first ESD protection tube, the second ESD protection tube, and the third ESD protection tube are all connected to ground.

10. An audio splitter, characterized in that, Includes the audio return circuit as described in any one of claims 1-9.

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