A burning circuit and mainboard for audio chip

Abstract

The embodiment of the present invention discloses a burning circuit and a mainboard applied to an audio chip, wherein the burning circuit is used to connect to a CPU, and the burning circuit includes an interface unit, a first selection unit, a second selection unit and a switch unit, wherein the switch unit is connected to the CPU, the first selection unit and the second selection unit respectively, and the switch unit includes a switch tube, wherein the switch tube is used to conduct or shut down according to a signal output by the CPU to output a first control signal or a second control signal to the first selection unit and the second selection unit, wherein the first selection unit is used to connect the audio chip to the second selection unit based on the first control signal, or to connect the CPU to the audio chip based on the second control signal, and the second selection unit is used to connect the first selection unit to the interface unit based on the first control signal, or to connect the CPU to the interface unit based on the second control signal. In the above manner, the firmware of the audio chip can be upgraded without disassembling the device.

Description

Technical Field

[0001] The present invention relates to the field of circuit technology, and in particular to a burning circuit and a mainboard applied to an audio chip. Background Art

[0002] Firmware refers to the device "driver" stored inside the device. Through firmware, the system can implement the operating actions of a specific machine according to standard device drivers.

[0003] Similarly, during the use of audio devices, in order to improve device functions, enhance device stability, patch device vulnerabilities, and meet usage needs, it is also necessary to upgrade the firmware of the audio chip and update the device software firmware.

[0004] However, when upgrading the firmware of an existing audio chip, it is necessary to connect an external USB pin to the audio chip, and the audio device must be disassembled first. Summary of the Invention

[0005] The main technical problem solved by the embodiments of the present invention is to provide a burning circuit and a mainboard applied to an audio chip, which can upgrade the firmware of the audio chip without disassembling the device.

[0006] To achieve the above objectives, in a first aspect, the present invention provides a burning circuit for an audio chip, wherein the burning circuit is connected to a CPU and comprises:

[0007] An interface unit, a first selection unit, a second selection unit, and a switch unit;

[0008] The switch unit is connected to the CPU, the first selection unit, and the second selection unit respectively, and includes a switch tube, which is used to be turned on or off according to the signal output by the CPU to output a first control signal or a second control signal to the first selection unit and the second selection unit;

[0009] The first selection unit is connected to the CPU, the second selection unit, and the audio chip respectively, and the first selection unit is used to connect the audio chip to the second selection unit based on the first control signal, or to connect the CPU to the audio chip based on the second control signal;

[0010] The second selection unit is connected to the CPU, the first selection unit and the interface unit respectively, and the second selection unit is used to connect the first selection unit to the interface unit based on the first control signal so that the audio chip is connected to the interface unit, or to connect the CPU to the interface unit based on the second control signal.

[0011] In an optional manner, the first selection unit includes a first analog switch chip, and the first analog switch chip includes a first input port and a first output port;

[0012] The second selection unit includes a second analog switch chip, and the second analog switch chip includes a second input port and a second output port;

[0013] The first input port is short-circuited with the second input port, the first output port is connected to the audio chip, and the second output port is connected to the interface unit.

[0014] In an optional manner, the first analog switch chip further includes a third input port;

[0015] The second analog switch chip further includes a fourth input port;

[0016] The third input port and the fourth input port are both connected to the CPU.

[0017] In an optional manner, the first selection unit further includes a first filter capacitor;

[0018] The first analog switch chip further includes a first power input pin;

[0019] One end of the first filter capacitor is connected to the first power input pin, and the other end of the first filter capacitor is grounded.

[0020] In an optional manner, the second selection unit further includes a second filter capacitor;

[0021] The second analog switch chip further includes a second power input pin;

[0022] One end of the second filter capacitor is connected to the second power input pin, and the other end of the second filter capacitor is grounded.

[0023] In an optional manner, the switch tube is a MOS tube;

[0024] The first analog switch chip further includes a first control signal input pin;

[0025] The second analog switch chip further includes a second control signal input pin;

[0026] The gate of the MOS transistor is connected to the CPU, the source of the MOS transistor is grounded, and the drain of the MOS transistor is connected to the first control signal input pin and the second control signal input pin respectively. In an optional embodiment, the switch unit further includes a first resistor;

[0027] The drain of the MOS tube is connected to one end of the first resistor, and the other end of the first resistor is connected to the working power supply;

[0028] The first control signal input pin and the second control signal input pin are both connected between the drain of the MOS tube and the first resistor.

[0029] In an optional manner, the programming circuit further includes a connecting unit, and the connecting unit includes a second resistor and a third resistor;

[0030] The second output port includes a first output pin and a second output pin;

[0031] The interface unit includes a first differential signal pin and a second differential signal pin;

[0032] Two ends of the second resistor are connected to the first differential signal pin and the first output pin respectively;

[0033] Two ends of the third resistor are connected to the second differential signal pin and the second output pin respectively.

[0034] In an optional manner, the programming circuit further includes a voltage stabilizing unit, and the voltage stabilizing unit includes a first bidirectional voltage stabilizing diode and a second bidirectional voltage stabilizing diode;

[0035] One end of the first bidirectional voltage regulator diode is connected to the first differential signal pin, one end of the second bidirectional voltage regulator diode is connected to the second differential signal pin, and the other end of the first bidirectional voltage regulator diode and the other end of the second bidirectional voltage regulator diode are both grounded.

[0036] In a second aspect, an embodiment of the present invention further provides a mainboard, which includes an audio chip and the burning circuit as described above, wherein the burning circuit is used to implement firmware upgrade of the audio chip.

[0037] The beneficial effects of the embodiments of the present invention are as follows: the burning circuit for audio chips provided by the embodiments of the present invention includes an interface unit, a first selection unit, a second selection unit and a switch unit, and the switch unit is connected to the CPU, the first selection unit and the second selection unit respectively, and the switch unit is used to be turned on or off according to the signal output by the CPU to output a first control signal or a second control signal to the first selection unit and the second selection unit, wherein, when the switch unit is turned on, the first control signal output on the switch unit controls the first selection unit to connect the audio chip to the second selection unit, and at the same time controls the second selection unit to connect the first selection unit to the interface unit, that is, the audio chip is connected to the interface unit, and the firmware of the audio chip can be upgraded at this time without disassembling the machine; when the switch unit is turned off, the second control signal output on the switch unit controls the first selection unit to connect the CPU to the audio chip, and at the same time controls the second selection unit to connect the CPU to the interface unit, and the audio chip is in normal working state. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] One or more embodiments are exemplarily illustrated by pictures in the corresponding drawings. These exemplifications do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings are represented as similar elements. Unless otherwise stated, the figures in the drawings do not constitute proportional limitations.

[0039] Figure 1 A schematic diagram of the structure of a mainboard provided in an embodiment of the present invention;

[0040] Figure 2 A schematic diagram showing the structure of the connection between the programming circuit provided in an embodiment of the present invention and the CPU and audio chip;

[0041] Figure 3 A schematic diagram of the circuit structure of a switch unit provided in an embodiment of the present invention;

[0042] Figure 4 Another structural diagram showing the connection between the programming circuit provided in an embodiment of the present invention and the CPU and audio chip;

[0043] Figure 5 A schematic diagram of the internal structures of a first analog switch chip and a second analog switch chip provided in an embodiment of the present invention;

[0044] Figure 6 A schematic diagram of the circuit structure of an interface unit provided in an embodiment of the present invention;

[0045] Figure 7 A schematic diagram of the circuit structure of a first selection unit provided in an embodiment of the present invention;

[0046] Figure 8A schematic diagram of the circuit structure of a second selection unit provided in an embodiment of the present invention;

[0047] Figure 9 Another structural diagram of the programming circuit provided in an embodiment of the present invention connected to a CPU and an audio chip;

[0048] Figure 10 A schematic diagram of the circuit structure of a connecting unit and a voltage stabilizing unit provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0049] To make the purpose, technical solutions, and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0050] The embodiment of the present invention provides a motherboard, please refer to Figure 1 , Figure 1 This is a structural diagram of a motherboard provided by an embodiment of the present invention. The motherboard 400 includes a CPU 200, a burning circuit 100, and an audio chip 300. The burning circuit 100 is connected to the audio chip 300 and the COU 200, respectively.

[0051] Specifically, by setting the burning circuit 100 , the audio chip 300 can be switched between the working state and the debugging state. If the audio chip 300 is switched to the debugging state, the firmware of the audio chip 300 can be upgraded.

[0052] Please combine Figure 1 Reference Figure 2 The programming circuit 100 includes a switch unit 10 , a first selection unit 20 , a second selection unit 30 and an interface unit 40 .

[0053] Specifically, the switch unit 10 is connected to the CPU 200, the first selection unit 20 and the second selection unit 30 respectively. The switch unit 10 includes a switch tube 11. The switch tube 11 can be turned on or off according to the signal output by the CPU 200 to output the first control signal or the second control signal to the first selection unit 20 and the second selection unit 30.

[0054] In some embodiments, as Figure 3As shown, the switch tube 11 is a MOS tube Q1, the gate of the MOS tube Q1 is connected to the CPU 200, that is, the UARTA_P80_EN pin is connected to the CPU 200, the source of the MOS tube Q1 is grounded, and the drain of the MOS tube Q1 is connected to the first analog chip and the second analog chip respectively through the wiring UART_USB_SEL.

[0055] Furthermore, the switch unit 10 also includes a first resistor R1, the drain of the MOS tube Q1 is connected to one end of the first resistor R1, the other end of the first resistor R1 is connected to the external power supply +3V3_DSW, and the connection UART_USB_SEL is used to output the first control signal or the second control signal.

[0056] It is understandable that in other embodiments, an IGBT switch tube or a triode switch tube may be used to replace the MOS tube Q1 in the switch unit 10 .

[0057] In actual applications, if the signal output by the CPU 200 is a high-level signal, the high-level signal is transmitted to the gate of the MOS transistor Q1 through the UARTA_P80_EN pin, and the MOS transistor Q1 is turned on, so that the drain of the MOS transistor Q1 is short-circuited to the ground after passing through the source. Then, any connection point between the first resistor R1 and the MOS transistor Q1 is a low-level signal. For example, the signal output by the connection UART_USB_SEL at this time is a low-level signal. This low-level signal can be used as the first control signal or the second control signal.

[0058] On the contrary, if the signal output by CPU200 is a low-level signal, the low-level signal is transmitted to the gate of the MOS transistor Q1 through the UARTA_P80_EN pin, turning off the MOS transistor Q1. The drain and source of the MOS transistor Q1 are disconnected, and the drain of the MOS transistor Q1 is connected to the external power supply +3V3_DSW through the first resistor R1. Then, any connection point between the first resistor R1 and the MOS transistor Q1 is a high-level signal, and the signal output by the wiring UART_USB_SEL is a high-level signal. The high-level signal can be used as the first control signal or as the second control signal.

[0059] It should be understood that if the low-level signal output by the wiring UART_USB_SEL is the first control signal, the high-level signal output by the wiring UART_USB_SEL is the second control signal; if the high-level signal output by the wiring UART_USB_SEL is the first control signal, the low-level signal output by the wiring UART_USB_SEL is the second control signal.

[0060] The first selection unit 20 is connected to the CPU 200 , the second selection unit 30 and the audio chip 300 , respectively. The second selection unit 30 is connected to the CPU 200 , the first selection unit 20 and the interface unit 40 , respectively.

[0061] If you want to upgrade the firmware of the audio chip 300, please Figure 2 Reference Figure 4 , the switch unit 10 outputs the first control signal to control the first selection unit 20 to connect the audio chip 300 to the second selection unit 30, that is, the audio chip 300 is connected to the second selection unit 30 through the connection L11, the first selection unit 20 and the connection L10; at the same time, the second selection unit 30 is controlled to connect the first selection unit 20 to the interface unit 40, that is, the interface unit 40 is connected to the first selection unit 20 through the connection L12, the second selection unit 30 and the connection L10.

[0062] In summary, the audio chip 300 is connected to the interface unit 40 through the connection L11, the first selection unit 20, the connection L10, the second selection unit 30 and the connection L21, that is, the audio chip 300 is connected to the interface unit 40, and then the firmware upgrade and other operations of the audio chip 300 can be realized through the interface unit 40.

[0063] For example, the first selection unit 20 and the second selection unit 30 both use the PI3USB221AZEE analog switch chip, and the interface unit 40 uses the USB interface.

[0064] The internal structure diagram of the PI3USB221AZEE analog switch chip is as follows: Figure 5 As shown, pin SEL and pin OE# are control signal input pins, and the control logic of the analog switch chip is shown in Table 1:

[0065] Table 1

[0066] SEL OE# Function X H Disconnect L L D=1D H L D=2D

[0067] If both pin SEL and pin OE# input a low level, the upper switch is closed, and D+ and D- are connected to 1D+ and 1D- respectively; if pin SEL inputs a high level and pin OE# inputs a low level, the lower switch is closed, and D+ and D- are connected to 2D+ and 2D- respectively; if pin OE# inputs a low level, the analog switch chip does not perform any action.

[0068] In the embodiment of the present invention, the pin OE# of each analog switch chip is grounded, and the pin SEL is connected to the output pins of the first control signal and the second control signal of the switch unit 10, for example. Figure 3The wiring UART_USB_SEL shown is connected to the SEL pins of each analog switch chip at the same time.

[0069] like Figure 6 As shown, the interface unit 40 includes a USB interface chip U4, and the differential signal port U4_D of the USB interface chip U4 is a connection port for signal transmission, wherein the differential signal port U4_D includes a first differential signal pin D+ and a second differential signal pin D-.

[0070] Please refer to Figure 7 and Figure 8 The first selection unit 20 includes a first analog switch chip U2, which includes a first input port U2_1D and a first output port U2_D; the second selection unit 30 includes a second analog switch chip U3, which includes a second input port U3_1D and a second output port U3_D.

[0071] Among them, the first input port U2_1D is short-circuited with the second input port U3_1D, that is, pin 1D+ and pin 1D- in the first input port U2_1D are respectively connected to pin 1D+ and pin 1D- in the second input port U3_1D; the first output port U2_D is connected to the audio chip 300; the second output port U3_D is connected to the differential signal port U4_D of the interface unit 40, that is, pin D+ and pin D- in the second output port U3_D are respectively connected to the first differential signal pin D+ and the second differential signal pin D- in the differential signal port U4_D.

[0072] Specifically, the second input port U3_1D is first short-circuited with the first input port U2_1D. When the audio chip 300's firmware is to be upgraded, the first analog switch chip U2 connects the first input port U2_1D to the first output port U2_D, which in turn connects the first output port U2_D to the audio chip 300, thereby connecting the second input port U3_1D to the audio chip 300. Simultaneously, the second analog switch chip U3 connects the second input port U3_1D to the second output port U3_D, connecting the second output port U3_D to the differential signal port U4_D of the interface unit 40. This means that the second input port U3_1 is also connected to the interface unit 40. Therefore, the second input port U3_1D is connected to both the audio chip 300 and the interface unit 40, ultimately connecting the audio chip 300 to the interface unit 40. Operations such as firmware upgrades on the audio chip 300 can be performed through the interface unit 40.

[0073] If the audio chip 300 is switched to normal working state, please combine Figure 1 Reference Figure 9, the second control signal of the switch unit 10 controls the first selection unit 20 to connect the CPU 200 to the audio chip 300, that is, the CPU 200 is connected to the audio chip 300 through the connection L12, the first selection unit 20 and the connection L11; and at the same time controls the second selection unit 30 to connect the CPU 200 to the interface unit 40, that is, the CPU 200 is connected to the interface unit 40 through the connection L22, the second selection unit 30 and the connection L21.

[0074] The CPU 200 can be connected to the audio chip 300 and the interface unit 40 respectively, so that the audio chip 300 can be switched to a normal working state.

[0075] Please refer again Figure 7 and Figure 8 The first analog switch chip U2 further includes a third input port U2_2D, and the second analog switch chip U3 further includes a fourth input port U3_2D. Both the third input port U2_2D and the fourth input port U3_2D are connected to the CPU 200.

[0076] First, CPU 200 is connected to the third input port U2_2D. When the audio chip 300 is switched to normal operation, the first analog switch chip U2 connects the third input port U2_2D to the first output port U2_D. Since the first output port U2_D is connected to the audio chip 300, the CPU 200 is connected to the audio chip 300. Simultaneously, CPU 200 is connected to the fourth input port U3_2D, and the second analog switch chip U3 connects the fourth input port U3_2D to the second output port U3_D. Since the second output port U3_D is connected to the differential signal port U4_D of the interface unit 40, the CPU 200 is connected to the interface unit 40. At this point, the audio chip 300 is in normal operation.

[0077] It should be noted that other types of analog switch chips can also be selected, such as the PI3USB221AZUAEX model analog switch chip; or an analog switch chip with more than two channels or less than two channels can be selected, for example, a four-channel analog switch chip with model MC74LVX4066 can be selected, and any two channels can be selected for use; and the models of the first analog switch chip U2 and the second analog switch chip U3 can be the same or different.

[0078] Optional, see again Figure 7 The first selection unit 20 also includes a first filter capacitor C1, and the first analog switch chip U2 also includes a first power input pin VDD, wherein one end of the first filter capacitor C1 is connected to the first power input pin VDD of the first analog switch chip U2, and the other end of the first filter capacitor C1 is grounded.

[0079] The first filter capacitor C1 is used to eliminate high-frequency noise that may be present in the power supply +3V3_S0 inputted by the first power input pin VDD of the first analog switch chip U2 , thereby enabling the first analog switch chip U2 to operate in a more stable state.

[0080] Again, please refer to Figure 8 The second selection unit 30 also includes a second filter capacitor C2, the second analog switch chip U3 also includes a second power input pin VDD, one end of the second filter capacitor C2 is connected to the second power input pin VDD of the second analog switch chip U3, and the other end of the second filter capacitor C2 is grounded.

[0081] The second filter capacitor C2 is used to eliminate high-frequency noise that may be present in the power supply +3V3_S0 inputted by the second power input pin VDD of the second analog switch chip U3, thereby enabling the second analog switch chip U3 to operate in a more stable state.

[0082] In one embodiment, if Figure 10 As shown, the programming circuit further includes a connecting unit 50 , and the connecting unit 50 includes a second resistor R2 and a third resistor R3 .

[0083] For details, please refer to Figure 5 and Figure 7 The second resistor R2 and the third resistor R3 are both connected between the second output port U3_D and the differential signal port U4_D, wherein the two ends of the second resistor R2 are respectively connected to the pin D+ of the second output port U3_D and the first differential signal pin D+ of the differential signal port U4_D; the two ends of the third resistor R3 are respectively connected to the pin D- of the second output port U3_D and the second differential signal pin D- of the differential signal port U4_D.

[0084] Alternatively, as Figure 10 As shown, the programming circuit further includes a voltage stabilizing unit 60 , which includes a first bidirectional voltage stabilizing diode D1 and a second bidirectional voltage stabilizing diode D2 .

[0085] Among them, one end of the first bidirectional voltage regulator diode D1 is connected to the first differential signal pin D+ of the differential signal port U4_D, one end of the second bidirectional voltage regulator diode D2 is connected to the second differential signal pin D- of the differential signal port U4_D, and the other end of the first bidirectional voltage regulator diode D1 and the other end of the second bidirectional voltage regulator diode D2 are both grounded.

[0086] The bidirectional voltage regulator diode has a voltage stabilizing effect in both the forward and reverse directions, just like two voltage regulator diodes are connected in reverse series. When the bidirectional voltage regulator diode breaks down in the reverse direction, the terminal voltage can remain almost unchanged within a certain current range or a certain power loss range. The first bidirectional voltage regulator diode D1 and the second bidirectional voltage regulator diode D2 can eliminate the static error.

[0087] The burning circuit 100 for an audio chip provided by an embodiment of the present invention includes a switch unit 10, a first selection unit 20, a second selection unit 30 and an interface unit 40, and the switch unit 10 is connected to the CPU 200, the first selection unit 20 and the second selection unit 30 respectively. The switch unit 10 is used to turn on or off according to the signal output by the CPU 200 to output a first control signal or a second control signal to the first selection unit 20 and the second selection unit 30. When the switch unit 10 is turned on, the first control signal output on the switch unit 10 controls the first selection unit 20. Connect the audio chip 300 to the second selection unit 30, and at the same time control the second selection unit 30 to connect the first selection unit 20 to the interface unit 40, that is, connect the audio chip 300 to the interface unit 40. At this time, the firmware of the audio chip 300 can be upgraded without disassembling the machine; when the switch unit 10 is turned off, the first control signal output on the switch unit 10 controls the first selection unit 20 to connect the CPU 200 to the audio chip 300, and at the same time controls the second selection unit 30 to connect the CPU 200 to the interface unit 40. At this time, the audio chip 300 is in normal working state.

[0088] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Under the idea of ​​the present invention, the technical features in the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of different aspects of the present invention as described above. For the sake of simplicity, they are not provided in detail. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in this field should understand that they can still modify the technical solutions described in the above embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of this application.

Claims

1. A burning circuit applied to an audio chip, characterized in that: The burning circuit is used to be connected to the CPU, and the burning circuit comprises: An interface unit, a first selection unit, a second selection unit and a switch unit; The switch unit is connected to the CPU, the first selection unit and the second selection unit respectively, and the switch unit includes a switch tube, and the switch tube is used to be turned on or off according to the signal output by the CPU to output a first control signal or a second control signal to the first selection unit and the second selection unit; The first selection unit is connected to the CPU, the second selection unit and the audio chip respectively, and the first selection unit is used to connect the audio chip to the second selection unit based on the first control signal, or to connect the CPU to the audio chip based on the second control signal; The second selection unit is connected to the CPU, the first selection unit and the interface unit respectively, and the second selection unit is used to connect the first selection unit to the interface unit based on the first control signal so that the audio chip is connected to the interface unit, or to connect the CPU to the interface unit based on the second control signal; The first selection unit includes a first analog switch chip, and the first analog switch chip includes a first input port and a first output port; The second selection unit includes a second analog switch chip, and the second analog switch chip includes a second input port and a second output port; The first input port is short-circuited with the second input port, the first output port is connected with the audio chip, and the second output port is connected with the interface unit; The switch tube is a MOS tube; The first analog switch chip also includes a first control signal input pin; The second analog switch chip also includes a second control signal input pin; The gate of the MOS tube is connected to the CPU, the source of the MOS tube is grounded, and the drain of the MOS tube is respectively connected to the first control signal input pin and the second control signal input pin; The programming circuit further includes a connecting unit, and the connecting unit includes a second resistor and a third resistor; The second output port includes a first output pin and a second output pin; The interface unit includes a first differential signal pin and a second differential signal pin; Two ends of the second resistor are respectively connected to the first differential signal pin and the first output pin; Two ends of the third resistor are connected to the second differential signal pin and the second output pin respectively.

2. The programming circuit according to claim 1, characterized in that: The first analog switch chip also includes a third input port; The second analog switch chip also includes a fourth input port; The third input port and the fourth input port are both connected to the CPU.

3. The burning circuit according to claim 2, characterized in that: The first selection unit further includes a first filter capacitor; The first analog switch chip also includes a first power input pin; One end of the first filter capacitor is connected to the first power input pin, and the other end of the first filter capacitor is grounded.

4. The burning circuit according to claim 3, characterized in that: The second selection unit further includes a second filter capacitor; The second analog switch chip also includes a second power input pin; One end of the second filter capacitor is connected to the second power input pin, and the other end of the second filter capacitor is grounded.

5. The burning circuit according to claim 1, characterized in that: The switch unit further includes a first resistor; The drain of the MOS tube is connected to one end of the first resistor, and the other end of the first resistor is connected to a working power supply; The first control signal input pin and the second control signal input pin are both connected between the drain of the MOS tube and the first resistor.

6. The programming circuit according to claim 1, characterized in that: The programming circuit further includes a voltage stabilizing unit, and the voltage stabilizing unit includes a first bidirectional voltage stabilizing diode and a second bidirectional voltage stabilizing diode; One end of the first bidirectional zener diode is connected to the first differential signal pin, one end of the second bidirectional zener diode is connected to the second differential signal pin, and the other end of the first bidirectional zener diode and the other end of the second bidirectional zener diode are both grounded.

7. A motherboard, characterized in that: The mainboard includes an audio chip and a burning circuit as described in any one of claims 1 to 6, wherein the burning circuit is connected to the audio chip, and the burning circuit is used to implement a firmware upgrade of the audio chip.

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