Overvoltage protection circuit and wireless audio transceiver

Abstract

The utility model relates to the technical field of circuit protection, and relates to an overvoltage protection circuit and a wireless audio transceiver. The circuit comprises a first protection circuit module and a second protection circuit module, the first protection circuit module is arranged between a left channel end and a first sampling pin, and the second protection circuit module is arranged between a right channel end and a second sampling pin; the first protection circuit module comprises a first resistor, a first capacitor, a first voltage stabilizing diode and a second voltage stabilizing diode, the first end of the first resistor is electrically connected with the first end of the first capacitor and the left channel end, and the second end of the first resistor is electrically connected with the second end of the first capacitor and the negative electrode of the first voltage stabilizing diode and is electrically connected to the first sampling pin; the anode of the first voltage-regulator diode is electrically connected with the anode of the second voltage-regulator diode, and the cathode of the second voltage-regulator diode is grounded; the second protection circuit module and the first protection circuit module sample the same circuit. According to the application, the risk of damaging the post-stage audio sampling chip can be reduced, and distortion and harmonic waves are reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of audio interface protection, in particular to an overvoltage protection circuit and a wireless audio transceiver. Background Art

[0002] The rise of short videos, live streaming, and streaming media has significantly driven market demand for related creative tools. Wireless audio transceivers are highly sought after by creators for their compact size, portability, and freedom from cable constraints. However, due to size limitations, wireless audio transceivers typically use the 3.5mm jack commonly used on mobile devices. This audio jack allows for a maximum input / output level of no more than 3Vrms. Some signal source devices, such as small recording mixers and professional USB sound cards, require phantom power to drive high-impedance condenser microphones. These power supply voltages range from 12V DC, 24V DC, and 48V DC. Connecting a wireless audio transceiver's audio interface to such devices via an adapter cable can cause high voltage to enter the device, potentially causing serious problems such as overheating, short circuits, and even damage. Therefore, incorporating overvoltage protection circuitry into wireless audio transceivers is essential. Commonly used overvoltage protection circuit components include transient voltage suppressor diodes (TVSs), which offer fast protection and compact size, and varistors, which offer nonlinearity and high energy absorption capabilities.

[0003] However, the above-mentioned transient voltage suppression diodes and varistors have a high residual voltage after breakdown when performing overvoltage protection. After the voltage protection circuit is clamped, the voltage is still too high and enters the internal circuit through the line, which still poses a risk of damaging the subsequent audio sampling chip. In addition, the existing overvoltage protection circuit will cause large distortion of the audio signal and large harmonics. Utility Model Content

[0004] The present invention provides an overvoltage protection circuit and a wireless audio transceiver to address the problems in the prior art of wireless audio transceivers in which the overvoltage protection circuit still causes the clamping voltage to be too high, which can enter the internal circuit through the wiring and still damage the audio sampling chip. The problems also include significant audio signal distortion and high harmonics.

[0005] The utility model discloses an overvoltage protection circuit, which is applied to a wireless audio transceiver. The wireless audio transceiver includes an audio interface and an audio sampling chip. The overvoltage protection circuit is arranged between the audio interface and the audio sampling chip. The audio interface includes a left channel end and a right channel end. The audio sampling chip includes a first sampling pin and a second sampling pin. The overvoltage protection circuit includes a first protection circuit module and a second protection circuit module. The first protection circuit module is arranged between the left channel end and the first sampling pin, and the second protection circuit module is arranged between the right channel end and the second sampling pin.

[0006] Wherein, the first protection circuit module includes a first resistor, a first capacitor, a first voltage-stabilizing diode and a second voltage-stabilizing diode, the first end of the first resistor is electrically connected to the first end of the first capacitor and the left channel end, the second end of the first resistor is electrically connected to the second end of the first capacitor and the cathode of the first voltage-stabilizing diode and is electrically connected to the first sampling pin, the anode of the first voltage-stabilizing diode is electrically connected to the anode of the second voltage-stabilizing diode, and the cathode of the second voltage-stabilizing diode is grounded;

[0007] The second protection circuit module includes a second resistor, a second capacitor, a third Zener diode and a fourth Zener diode. The first end of the second resistor is electrically connected to the first end of the second capacitor and the right channel end, the second end of the second resistor is electrically connected to the second end of the second capacitor and the negative electrode of the third Zener diode and is electrically connected to the second sampling pin, the positive electrode of the third Zener diode is electrically connected to the positive electrode of the fourth Zener diode, and the negative electrode of the fourth Zener diode is grounded.

[0008] Optionally, the first protection circuit module further includes a third capacitor, a first end of the third capacitor is electrically connected to the first end of the first resistor, the first end of the first capacitor and the left channel end, and a second end of the third capacitor is grounded.

[0009] Optionally, the first protection circuit module further includes a fourth capacitor, a first end of the fourth capacitor is electrically connected to the second end of the first resistor, the second end of the first capacitor and the cathode of the first Zener diode, and a second end of the fourth capacitor is electrically connected to the first sampling pin.

[0010] Optionally, the second protection circuit module further includes a fifth capacitor, a first end of the fifth capacitor is electrically connected to the first end of the second resistor, the first end of the second capacitor and the right channel end, and a second end is grounded.

[0011] Optionally, the second protection circuit module further includes a sixth capacitor, a first end of the sixth capacitor is electrically connected to the second end of the second resistor, the second end of the second capacitor and the cathode of the third zener diode, and a second end is electrically connected to the second sampling pin.

[0012] Optionally, the resistance value of the first resistor is 3.1K±1%, and the resistance value of the second resistor is 3.1K±1%.

[0013] Optionally, the capacity of the first capacitor is 22uF±10%, and the capacity of the second capacitor is 22uF±10%.

[0014] Optionally, the capacity of the third capacitor is 15PF±10%, and the capacity of the fourth capacitor is 22uF±10%.

[0015] Optionally, the capacity of the fifth capacitor is 15PF±10%, and the capacity of the sixth capacitor is 22uF±10%.

[0016] The utility model also discloses a wireless audio transceiver, including an audio interface, an audio sampling chip and the overvoltage protection circuit as described above. The audio interface includes a left channel end and a right channel end. The audio sampling chip includes a first sampling pin and a second sampling pin. The first protection circuit module of the overvoltage protection circuit is arranged between the left channel end and the first sampling pin, and the second protection circuit module of the overvoltage protection circuit is arranged between the right channel end and the second sampling pin.

[0017] Compared with the prior art, the overvoltage protection circuit provided by the embodiments of the present invention has the following advantages: the overvoltage protection circuit of the present invention is provided with a first protection circuit module and a second protection module. The first protection circuit module is provided between the left channel end of the audio interface and the first sampling pin of the audio sampling chip, and the second protection circuit module is provided between the right channel end and the second sampling pin. The first protection circuit module includes a first capacitor, a first resistor, a first Zener diode, and a second Zener diode. The first end of the first resistor is electrically connected to the first end of the first capacitor and the left channel end, the second end of the first resistor is electrically connected to the second end of the first capacitor and the cathode of the first Zener diode and electrically connected to the first sampling pin, the anode of the first Zener diode is electrically connected to the anode of the second Zener diode, and the cathode of the second Zener diode is grounded. In the first protection circuit module and the second protection circuit module, the capacitors enable rapid transmission of audio signals; the resistors provide current limiting, and the two Zener diodes form a clamping circuit, so that any input voltage signal with a wide amplitude can be limited to a lower voltage range by the clamping circuit, reducing the risk of damaging the subsequent audio sampling chip and reducing distortion and harmonics of the audio signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments, in which:

[0019] Figure 1 This is a structural block diagram of the overvoltage protection circuit of an embodiment of the utility model;

[0020] Figure 2 It is a circuit diagram of an overvoltage protection circuit according to an embodiment of the present utility model.

[0021] The reference numerals in the figures are:

[0022] 10. Audio interface; 11. Left channel terminal; 12. Right channel terminal; 20. Audio sampling chip; 21. First sampling pin; 22. Second sampling pin; 30. Overvoltage protection circuit; 31. First protection circuit module; 32. Second protection circuit module;

[0023] R1, first resistor; R2, second resistor; C1, first capacitor; C2, second capacitor; C3, third capacitor; C4, fourth capacitor; C5, fifth capacitor; C6, sixth capacitor; D1, first Zener diode; D2, second Zener diode; D3, third Zener diode; D4, fourth Zener diode. DETAILED DESCRIPTION

[0024] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. Now, in conjunction with the accompanying drawings, a detailed description of the preferred embodiments of the present utility model will be given.

[0025] The present invention provides an overvoltage protection circuit. Figure 1 and Figure 2 As shown, the overvoltage protection circuit 30 is provided between the audio interface 10 and the audio sampling chip 20. The audio interface 10 includes a left channel terminal 11 and a right channel terminal 12. The audio sampling chip 20 includes a first sampling pin 21 and a second sampling pin 22. The overvoltage protection circuit 30 includes a first protection circuit module 31 and a second protection circuit module 32. The first protection circuit module 31 is provided between the left channel terminal 11 and the first sampling pin 21, and the second protection circuit module 32 is provided between the right channel terminal 12 and the second sampling pin 22.

[0026] Among them, the first protection circuit module 31 includes a first resistor R1, a first capacitor C1, a first Zener diode D1 and a second Zener diode D2, the first end of the first resistor R1 is electrically connected to the first end of the first capacitor C1 and the left channel end 11, the second end of the first resistor R1 is electrically connected to the second end of the first capacitor C1 and the cathode of the first Zener diode D1 and is electrically connected to the first sampling pin 21, the anode of the first Zener diode D1 is electrically connected to the anode of the second Zener diode D2, and the cathode of the second Zener diode D2 is grounded.

[0027] The second protection circuit module 32 includes a second resistor R2, a second capacitor C2, a third Zener diode D3 and a fourth Zener diode. The first end of the second resistor R2 is electrically connected to the first end of the second capacitor C2 and the right channel terminal 12, the second end of the second resistor R2 is electrically connected to the second end of the second capacitor C2 and the cathode of the third Zener diode D3 and is electrically connected to the second sampling pin 22, the anode of the third Zener diode D3 is electrically connected to the anode of the fourth Zener diode, and the cathode of the fourth Zener diode is grounded.

[0028] Specifically, in the first protection circuit module 31, the first resistor R1 performs current limiting, and the first Zener diode D1 and the second Zener diode D2 form a clamping circuit. When the input AC audio signal voltage is lower than the breakdown voltage of the first Zener diode D1, the first Zener diode D1 does not conduct, and the AC audio signal is normally coupled into the audio sampling chip 20 through the first capacitor C1, and the product operates normally. When the input DC voltage is greater than the breakdown voltage of the first Zener diode D1, the first Zener diode D1 begins to break down and conduct, generating a certain current. The current is limited within a certain range by the first resistor R1, and the voltage across the first Zener diode D1 is basically stable near the breakdown voltage, thereby achieving a voltage stabilization function. In this state, the dynamic resistance of the Zener diode is very small, which means that when the current changes, the voltage change is also very small, so it can effectively maintain voltage stability. When the input is a DC voltage of 24V or 48V phantom power, the first Zener diode D1 is reversely broken down by the current limiting and voltage division of the first resistor R1, and the second Zener diode The diode D2 is forward-conducted, and the current of the first protection circuit module 31 passes through the first resistor R1, the first Zener diode D1, and the second Zener diode D2 and then forms a ground loop. When the first resistor R1 is 3.1K, the current is: 24 / (3100+1000Zzt)=0.00585A=5.85mA, or 48 / (3100+1000Zzt)=0.0117A=11.7mA. The voltage across the first Zener diode D1 is basically stable near the breakdown voltage. The voltage at the first Zener diode D1 is equal to the reverse breakdown voltage (Vz) of the first Zener diode D1 plus the Zener voltage (Vf). When the model of the first Zener diode D1 is LM3Z2V4T1G, the stabilized voltage at the first Zener diode D1 is: (Vz)2.4+(Vf)0.7=3.1V, which is lower than the power supply 3.3V of the subsequent audio sampling chip 20. It is within the allowable voltage range of the input / output port of the audio sampling chip 20 and can protect the subsequent audio sampling chip 20.

[0029] The first capacitor C1 is a coupling capacitor used to transmit audio signals. The first resistor R1 also limits the current in the circuit to prevent excessive current from damaging the series-connected components and also acts as a voltage divider. The second protection circuit module 32 operates on the same principles as the first protection circuit module 31 and will not be further described here.

[0030] As described above, the present invention uses a combination of multiple voltage stabilizing diodes and an RC circuit design to protect the audio sampling chip 20 , and can stably implement level clamping protection within a wide input voltage range, such as 3.4-48V.

[0031] Furthermore, using two Zener diodes to form a clamping circuit can significantly improve the problem of multiple harmonics in the audio input signal caused by a single Zener diode protection circuit, compared to a single Zener diode. The second harmonic level is reduced by 9.822dBV; the third harmonic is reduced by 22.86dBV:

[0032] Under the given test conditions, the second harmonic of a single zener diode is -52.63dBV, and the third harmonic is -36.63dBV. The second harmonic of a dual zener diode circuit is -62.45dBV, and the third harmonic is -57.47dBV.

[0033] Specifically, when using a single first Zener diode D1, when inputting a 1kHz sine wave audio signal at 1Vrms, the conventional single first Zener diode D1 provides protection, with only the first Zener diode D1 reverse biased to ground. During the positive half-cycle, the reverse bias of the first Zener diode D1 causes the audio signal to open to ground, resulting in normal audio signal. During the negative half-cycle, the first Zener diode D1 becomes forward-biased and conducts. This creates a signal path through ground, to the first Zener diode D1, to the capacitor, and then back to the signal source, causing signal clipping and distortion. By connecting the first Zener diode D1 in parallel with the second Zener diode D2, the total Zener junction capacitance is reduced, reducing the second and third harmonics of the audio signal, improving sound quality, increasing dynamic range, and enhancing system stability. Experiments show that when using a 1kHz sine wave audio signal at 1Vrms, the conventional single first Zener diode D1 provides protection, with a distortion of 6.742%. However, by switching to a series connection of the first and second Zener diodes D1 and D2, the distortion is reduced to 0.07%. The second protection circuit module 32 has the same principle and will not be described in detail here.

[0034] In a specific embodiment, Figure 2 As shown, the first protection circuit module 31 further includes a third capacitor C3 , a first end of the third capacitor C3 is electrically connected to the first end of the first resistor R1 , the first end of the first capacitor C1 and the left channel end 11 , and a second end is grounded.

[0035] The third capacitor C3 is a high-frequency bypass capacitor that effectively filters high-frequency noise from the first protection circuit module 31 while retaining low-frequency signals, thereby improving circuit performance and stability. Its operating principle is based on the capacitive reactance characteristic of a capacitor, which is inversely proportional to frequency: the higher the frequency, the smaller the capacitive reactance. Therefore, the third capacitor C3 allows high-frequency current to pass while blocking low-frequency current, thereby achieving a filtering effect.

[0036] In a specific embodiment, Figure 2 As shown, the first protection circuit module 31 further includes a fourth capacitor C4 , a first end of the fourth capacitor C4 electrically connected to the second end of the first resistor R1 , the second end of the first capacitor C1 and the cathode of the first Zener diode D1 , and a second end electrically connected to the first sampling pin 21 .

[0037] Among them, the fourth capacitor C4 is an audio coupling capacitor that allows the AC signal in the first protection circuit module 31 to pass normally, while blocking the DC signal of the upper circuit so that it will not affect the lower circuit. In the AC circuit, as the voltage of one pin of the capacitor gradually increases, the charge accumulated on the electrode plate connected to that pin also gradually increases; as the voltage gradually decreases, the charge accumulated on the corresponding electrode plate also gradually decreases. During the entire process, although no current actually passes through the capacitor, because it accumulates and releases charge as the potential increases and decreases, people mistakenly think that there is current passing. Therefore, the fourth capacitor C4 can allow AC current to pass but not DC current to flow, thereby achieving the coupling and isolation functions of the signal.

[0038] In a specific embodiment, Figure 2 As shown, the second protection circuit module 32 further includes a fifth capacitor C5 , a first end of the fifth capacitor C5 is electrically connected to the first end of the second resistor R2 , the first end of the second capacitor C2 and the right channel end 12 , and a second end is grounded.

[0039] The fifth capacitor C5 is a high-frequency bypass capacitor that effectively filters high-frequency noise from the second protection circuit module 32 while retaining low-frequency signals, thereby improving circuit performance and stability. Its operating principle is based on the capacitive reactance characteristic of a capacitor, which is inversely proportional to frequency: the higher the frequency, the smaller the capacitive reactance. Therefore, the fifth capacitor C5 allows high-frequency current to pass while blocking low-frequency current, thereby achieving a filtering effect.

[0040] In a specific embodiment, Figure 2 As shown, the second protection circuit module 32 further includes a sixth capacitor C6 , a first end of the sixth capacitor C6 electrically connected to the second end of the second resistor R2 , the second end of the second capacitor C2 and the cathode of the third zener diode D3 , and a second end electrically connected to the second sampling pin 22 .

[0041] The sixth capacitor C6 is an audio coupling capacitor that allows AC signals in the second protection circuit module 32 to pass normally while blocking DC signals from the previous circuit, preventing them from affecting the next circuit. In an AC circuit, as the voltage on one pin of the capacitor gradually increases, the charge accumulated on the electrode plate connected to that pin also gradually increases; as the voltage gradually decreases, the charge accumulated on the corresponding electrode plate also gradually decreases. Throughout this process, although no current actually flows through the capacitor, the phenomenon of charge accumulation and release as the potential increases and decreases can mistakenly lead people to believe that current is flowing. Therefore, the sixth capacitor C6 allows AC current to pass while preventing DC current from flowing, thereby achieving signal coupling and isolation functions.

[0042] Optionally, the resistance of the first resistor R1 is 3.1k ± 1%, and the resistance of the second resistor R2 is 3.1k ± 1%. The specific resistance values ​​of the first resistor R1 and the second resistor R2 can be set by the designer based on the selection of the corresponding voltage-stabilizing diode. Preferably, the resistance value of the first resistor R1 is 3.1k, and the resistance value of the second resistor R2 is 3.1k.

[0043] Optionally, the capacity of the first capacitor C1 is 22uF±10%, and the capacity of the second capacitor C2 is 22uF±10%. The specific capacity of the first capacitor C1 and the second capacitor C2 can be set by the designer according to the needs. Preferably, the capacity of the first capacitor C1 is selected as 22uF, and the capacity of the second capacitor C2 is selected as 22uF.

[0044] Optionally, the capacity of the third capacitor C3 is 15PF ± 10%, and the capacity of the fourth capacitor C4 is 22uF ± 10%. The specific capacity of the third capacitor C3 and the fourth capacitor C4 can be set by the designer according to the needs. Preferably, the capacity of the third capacitor C3 is 15PF, and the capacity of the fourth capacitor C4 is 22uF.

[0045] Optionally, the capacity of the fifth capacitor C5 is 15PF ± 10%, and the capacity of the sixth capacitor C6 is 22uF ± 10%. The specific capacity of the fifth capacitor C5 and the sixth capacitor C6 can be set by the designer according to the needs. Preferably, the capacity of the fifth capacitor C5 is selected as 15PF, and the capacity of the sixth capacitor C6 is selected as 22uF.

[0046] It should be noted that in the overvoltage protection circuit 30 provided by the present invention, the first protection circuit module 31 and the second protection circuit module 32 are the same circuit. The difference is that the first protection circuit module 31 is connected to the left channel, and the second protection circuit module 32 is connected to the right channel. The complexity of the two circuits is low and the cost of the components is low.

[0047] The present invention also discloses a wireless audio transceiver device, comprising an audio interface 10, an audio sampling chip 20, and the aforementioned overvoltage protection circuit 30. The audio interface 10 includes a left channel terminal 11 and a right channel terminal 12. The audio sampling chip 20 includes a first sampling pin 21 and a second sampling pin 22. A first protection circuit module 31 of the overvoltage protection circuit 30 is disposed between the left channel terminal 11 and the first sampling pin 21, and a second protection circuit module 32 of the overvoltage protection circuit 30 is disposed between the right channel terminal 12 and the second sampling pin 22. The wireless audio transceiver device, including the aforementioned overvoltage protection circuit 30, achieves the same technical effects as the aforementioned overvoltage protection circuit 30 and will not be further described herein.

[0048] It should be understood that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Those skilled in the art may modify the technical solutions described in the above embodiments, or make equivalent replacements for some of the technical features therein; and all these modifications and replacements should fall within the scope of protection of the claims attached to the present invention.

Claims

1. An overvoltage protection circuit, the overvoltage protection circuit being provided between an audio interface and an audio sampling chip, the audio interface including a left channel terminal and a right channel terminal, the audio sampling chip including a first sampling pin and a second sampling pin, characterized in that: The overvoltage protection circuit includes a first protection circuit module and a second protection circuit module, the first protection circuit module is arranged between the left channel end and the first sampling pin, and the second protection circuit module is arranged between the right channel end and the second sampling pin; The first protection circuit module includes a first resistor, a first capacitor, a first voltage-stabilizing diode, and a second voltage-stabilizing diode. The first end of the first resistor is electrically connected to the first end of the first capacitor and the left channel terminal. The second end of the first resistor is electrically connected to the second end of the first capacitor and the cathode of the first voltage-stabilizing diode and is electrically connected to the first sampling pin. The anode of the first voltage-stabilizing diode is electrically connected to the anode of the second voltage-stabilizing diode, and the cathode of the second voltage-stabilizing diode is grounded. The second protection circuit module includes a second resistor, a second capacitor, a third Zener diode and a fourth Zener diode. The first end of the second resistor is electrically connected to the first end of the second capacitor and the right channel end, the second end of the second resistor is electrically connected to the second end of the second capacitor and the cathode of the third Zener diode and is electrically connected to the second sampling pin, the anode of the third Zener diode is electrically connected to the anode of the fourth Zener diode, and the cathode of the fourth Zener diode is grounded.

2. The overvoltage protection circuit according to claim 1, wherein: The first protection circuit module further includes a third capacitor, a first end of which is electrically connected to the first end of the first resistor, the first end of the first capacitor and the left channel end, and a second end of which is grounded.

3. The overvoltage protection circuit according to claim 2, characterized in that: The first protection circuit module further includes a fourth capacitor, a first end of which is electrically connected to the second end of the first resistor, the second end of the first capacitor, and the cathode of the first Zener diode, and a second end of which is electrically connected to the first sampling pin.

4. The overvoltage protection circuit according to claim 1, wherein: The second protection circuit module further includes a fifth capacitor, a first end of which is electrically connected to the first end of the second resistor, the first end of the second capacitor and the right channel end, and a second end of which is grounded.

5. The overvoltage protection circuit according to claim 4, characterized in that: The second protection circuit module further includes a sixth capacitor, a first end of which is electrically connected to the second end of the second resistor, the second end of the second capacitor, and the cathode of the third zener diode, and a second end of which is electrically connected to the second sampling pin.

6. The overvoltage protection circuit according to claim 1, wherein: The resistance of the first resistor is 3.1K±1%, and the resistance of the second resistor is 3.1K±1%.

7. The overvoltage protection circuit according to claim 1, wherein: The capacity of the first capacitor is 22uF±10%, and the capacity of the second capacitor is 22uF±10%.

8. The overvoltage protection circuit according to claim 3, wherein: The capacity of the third capacitor is 15PF±10%, and the capacity of the fourth capacitor is 22uF±10%.

9. The overvoltage protection circuit according to claim 5, characterized in that: The capacity of the fifth capacitor is 15PF±10%, and the capacity of the sixth capacitor is 22uF±10%.

10. A wireless audio transceiver, characterized in that: The device comprises an audio interface, an audio sampling chip, and the overvoltage protection circuit according to any one of claims 1 to 9, wherein the audio interface includes a left channel terminal and a right channel terminal, the audio sampling chip includes a first sampling pin and a second sampling pin, a first protection circuit module of the overvoltage protection circuit is arranged between the left channel terminal and the first sampling pin, and a second protection circuit module of the overvoltage protection circuit is arranged between the right channel terminal and the second sampling pin.

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