A connector for preventing eavesdropping on a mobile phone

Abstract

This invention discloses an adapter for preventing mobile phone eavesdropping, comprising an adapter body integrating a dual Type-C interface module, a power matching circuit, a power management circuit, an LDO circuit, and a digital audio circuit. In the dual Type-C interface, the male Type-C1 connector connects to the mobile phone to transmit audio signals and receive charging voltage, while the female Type-C2 connector connects to an external charger for power. The power management circuit intelligently switches between charging and discharging modes based on signals such as VDET, charging the mobile phone and providing raw power to the LDO circuit. The LDO circuit regulates fluctuating voltage to power the digital audio circuit. The digital audio circuit takes over the mobile phone's audio path, cutting off malicious programs from direct connection to the microphone, achieving physical anti-eavesdropping while balancing charging and privacy protection.

Description

Technical Field

[0001] This invention relates to the field of anti-eavesdropping technology, specifically to an adapter for preventing mobile phone eavesdropping. Background Technology

[0002] With the widespread use of smartphones, user privacy and security face serious challenges, especially during calls or daily use, where microphones are easily hijacked by malicious programs, leading to eavesdropping and information leaks. Existing anti-eavesdropping measures have significant shortcomings: some rely on software protection, which is easily cracked; some hardware solutions require modifications to the phone's internal structure, resulting in poor compatibility and complex operation. Furthermore, most anti-eavesdropping devices are separate from charging functions, requiring users to carry multiple accessories when out and about, which is inconvenient. In addition, traditional adapters lack intelligent control over charging status, making it difficult to stably power audio chips, causing anti-eavesdropping functions to be susceptible to power fluctuations and posing a risk of protection failure. Therefore, the development of an anti-eavesdropping adapter integrating dual interfaces, charging management, and stable power supply is a practical necessity. Summary of the Invention

[0003] The purpose of this invention is to provide an adapter for preventing mobile phone eavesdropping, thereby solving the problems mentioned in the background art.

[0004] This invention is achieved through the following technical solution:

[0005] An adapter for preventing mobile phone eavesdropping, characterized in that it includes an adapter body, which integrates a dual Type-C interface module, a power matching circuit, a power management circuit, an LDO circuit, and a digital audio circuit. The connection relationship and function implementation of each module are as follows:

[0006] The dual TYPEC interface module includes a TYPEC1 interface and a TYPEC2 interface; the TYPEC1 interface is a male TYPEC connector used for physical connection with the mobile phone, transmitting the mobile phone's audio signals and receiving charging voltage; the TYPEC2 interface is a female TYPEC connector used for connection with an external charger to introduce external charging power.

[0007] The input terminal of the power matching circuit is connected in series with the VBUS pin of the TYPEC2 interface, and the output terminal is connected to the signal input terminal of the power management circuit. The power matching circuit is used to detect the power supply status of the external charger. After filtering out power supply noise through the built-in current limiting resistor and filter capacitor, it outputs the VDET detection signal and VEN_A / VEN_B enable signal to the power management circuit.

[0008] The power management circuit includes a charging management chip, whose signal input terminals are respectively connected to the VDET detection signal output terminal and the VEN_A / VEN_B enable signal output terminal of the power matching circuit, as well as the CC1 pin of the TYPEC1 interface and the CC2 pin of the TYPEC2 interface; its power input terminal is connected to the VBUS pin of the TYPEC2 interface, and its power output terminal is divided into two paths: one path is connected to the VBUS pin of the TYPEC1 interface, and the other path is connected to the input terminal of the LDO circuit; the power management circuit is used to intelligently switch between charging mode and discharging mode according to the VDET detection signal, the VEN_A / VEN_B enable signal, and the CC1 / CC2 pin signals, so as to provide charging voltage for the mobile phone and stable raw power for the LDO circuit;

[0009] The LDO circuit includes a low dropout regulator, with its input terminal connected to the power output terminal of the power management circuit and its output terminal connected to the power supply terminal of the digital audio circuit. The LDO circuit is used to regulate the fluctuating voltage output by the power management circuit into a fixed voltage, providing a stable power supply to the digital audio circuit that is unaffected by the charging and discharging state.

[0010] The digital audio circuit includes a digital audio chip, whose audio signal input terminal is connected to the Dp1 / Dn1 pins of the TYPEC1 interface, and its power supply terminal is connected to the output terminal of the LDO circuit. The digital audio circuit does not integrate independent speakers and microphones, but is only used to take over the audio input / output path of the mobile phone, cut off the direct connection between malicious programs and the mobile phone microphone, and achieve physical-level anti-eavesdropping.

[0011] Furthermore,

[0012] The power management circuit also includes N-channel MOSFETs Q14 and Q15;

[0013] The gates of MOSFETs Q14 and Q15 are both connected to the control terminal of the charging management chip. The sources of MOSFETs Q14 and Q15 are both grounded. The drain of MOSFET Q14 is connected to the CC1 pin of TYPEC1, and the drain of MOSFET Q15 is connected to the CC2 pin of TYPEC2.

[0014] Furthermore,

[0015] The charging mode trigger condition of the power management circuit is that the VDET detection signal is high, the VEN_A / VEN_B signal is active, and the pull-down signal of R53 is detected on the CC1 pin. At this time, the charging management chip turns on Q14 and Q15 to strengthen the detection of the TYPEC protocol signal on the CC1 and CC2 pins. At the same time, the charging voltage input to TYPEC2 is stepped down and regulated and then output to VBUS of TYPEC1 through the CHGCC1 / CHGCC2 pins to charge the mobile phone.

[0016] Furthermore,

[0017] The power management circuit's discharge mode is when the VDET detection signal is low. The charging management chip cuts off MOSFETs Q14 and Q15, stopping the output of charging voltage to TYPEC1, but continues to output VBAT voltage to the LDO circuit, ensuring that the digital audio circuit continues to work and the anti-eavesdropping function is not interrupted.

[0018] Furthermore,

[0019] The digital audio circuit also includes a digital audio chip and matching resistors R60, R61, R62, and R63. R60 is connected at one end to the VCMBUFR pin of the digital audio chip and at the other end to the MICP pin. R61 is connected at one end to the MICN pin and at the other end to VCMBUFL. R62 is connected in series with R60, with one end connected to the AUDIO pin of the digital audio chip and the other end grounded. R63 is connected in series with R61, with one end connected to the AUDIO pin of the digital audio chip and the other end grounded. All matching resistors work together to achieve impedance matching of the audio signal, preventing audio distortion caused by signal reflection.

[0020] The beneficial effects of this invention are as follows:

[0021] 1. This adapter takes over the phone's audio input / output path via digital audio circuitry, directly severing the connection between malicious programs and the phone's microphone, thus physically blocking eavesdropping channels. Compared to traditional software-based anti-eavesdropping methods (easily cracked and with poor protection stability), this hardware-level protection does not rely on the phone's system security. Even if the phone is compromised by malicious programs, they cannot bypass the adapter to obtain microphone signals, effectively protecting user privacy and security during calls, voice recordings, and other scenarios, significantly improving protection reliability.

[0022] 2. The adapter integrates dual Type-C interface modules. The Type-C1 male connector connects to the phone for eavesdropping prevention, while the Type-C2 female connector can be connected to an external charger to charge the phone, combining eavesdropping prevention with everyday charging needs. In traditional solutions, eavesdropping prevention devices and chargers are often separate accessories, requiring users to carry multiple devices when out and about, which is cumbersome and prone to loss. This adapter, however, requires only one accessory to meet both needs, greatly simplifying the carrying and usage process and improving daily convenience.

[0023] 3. The power management circuit can automatically switch between charging and discharging modes based on the VDET detection signal, VEN_A / VEN_B enable signals, and CC pin signals: When there is external power (charging mode), it provides a regulated charging voltage for the phone and power to the LDO circuit; when there is no external power (discharging mode), it immediately switches to powering the phone, obtaining the phone voltage through the TYPEC1 interface and processing it into VBAT voltage to continuously power the digital audio circuit. This intelligent switching avoids the problem of "anti-eavesdropping function failure when there is no external power." Whether the user is in an indoor charging scenario or an outdoor scenario without power, the anti-eavesdropping protection remains effective, providing extremely strong protection continuity and ensuring that the anti-eavesdropping function can be continuously triggered without interruption.

[0024] 4. The adapter uses an LDO circuit (including a low-dropout regulator and parallel filter capacitors C43 and C44) to regulate the fluctuating voltage output from the power management circuit to a fixed voltage, providing a stable power supply to the digital audio circuit unaffected by charging and discharging states. The filter capacitors remove high-frequency noise and ripple from the original voltage, and the LDO chip further achieves low-dropout regulation, preventing voltage fluctuations from causing the digital audio chip to crash or the audio path takeover to fail. Simultaneously, the digital audio circuit achieves impedance matching through matching resistors, preventing audio distortion caused by signal reflection, thus ensuring the continuous stability of the anti-eavesdropping function. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the system of the present invention;

[0026] Figure 2 This is a schematic diagram of the overall invention. Detailed Implementation

[0027] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0028] See the example. Figures 1 to 2 :

[0029] An adapter for preventing mobile phone eavesdropping, characterized in that it includes an adapter body, which integrates a dual Type-C interface module, a power matching circuit, a power management circuit, an LDO circuit, and a digital audio circuit. The connection relationship and function implementation of each module are as follows:

[0030] The dual TYPEC interface module includes a TYPEC1 interface and a TYPEC2 interface; the TYPEC1 interface is a male TYPEC connector used for physical connection with the mobile phone, transmitting the mobile phone's audio signals and receiving charging voltage; the TYPEC2 interface is a female TYPEC connector used for connection with an external charger to introduce external charging power.

[0031] The input terminal of the power matching circuit is connected in series with the VBUS pin of the TYPEC2 interface, and the output terminal is connected to the signal input terminal of the power management circuit. The power matching circuit is used to detect the power supply status of the external charger. After filtering out power supply noise through the built-in current limiting resistor and filter capacitor, it outputs the VDET detection signal and VEN_A / VEN_B enable signal to the power management circuit.

[0032] The power management circuit includes a charging management chip, whose signal input terminals are respectively connected to the VDET detection signal output terminal and the VEN_A / VEN_B enable signal output terminal of the power matching circuit, as well as the CC1 pin of the TYPEC1 interface and the CC2 pin of the TYPEC2 interface; its power input terminal is connected to the VBUS pin of the TYPEC2 interface, and its power output terminal is divided into two paths: one path is connected to the VBUS pin of the TYPEC1 interface, and the other path is connected to the input terminal of the LDO circuit; the power management circuit is used to intelligently switch between charging mode and discharging mode according to the VDET detection signal, the VEN_A / VEN_B enable signal, and the CC1 / CC2 pin signals, so as to provide charging voltage for the mobile phone and stable raw power for the LDO circuit;

[0033] The LDO circuit includes a low dropout regulator, with its input terminal connected to the power output terminal of the power management circuit and its output terminal connected to the power supply terminal of the digital audio circuit. The LDO circuit is used to regulate the fluctuating voltage output by the power management circuit into a fixed voltage, providing a stable power supply to the digital audio circuit that is unaffected by the charging and discharging state.

[0034] The digital audio circuit includes a digital audio chip, whose audio signal input terminal is connected to the Dp1 / Dn1 pins of the TYPEC1 interface, and its power supply terminal is connected to the output terminal of the LDO circuit. The digital audio circuit does not integrate independent speakers and microphones, but is only used to take over the audio input / output path of the mobile phone, cut off the direct connection between malicious programs and the mobile phone microphone, and achieve physical-level anti-eavesdropping.

[0035] Furthermore,

[0036] The power management circuit also includes N-channel MOSFETs Q14 and Q15;

[0037] The gates of MOSFETs Q14 and Q15 are both connected to the control terminal of the charging management chip. The sources of MOSFETs Q14 and Q15 are both grounded. The drain of MOSFET Q14 is connected to the CC1 pin of TYPEC1, and the drain of MOSFET Q15 is connected to the CC2 pin of TYPEC2.

[0038] The power management circuit of the adapter integrates two additional N-channel MOSFETs, Q14 and Q15, on top of the charging management chip. The circuit connection of the two follows precise control logic: the gates of MOSFETs Q14 and Q15 are directly connected to the control terminal of the charging management chip, and their on or off state is determined by the control signal output by the chip; the sources of Q14 and Q15 are grounded together, forming a common reference point for the circuit loop; the drain of Q14 is specifically connected to the CC1 pin of the TYPEC1 interface in the dual TYPEC interface module, and the drain of Q15 is connected to the CC2 pin of the TYPEC2 interface. The control path between the charging management chip and the CC pin of the TYPEC interface is established through these two MOSFETs.

[0039] Since the CC pin is a key pin in the TYPEC protocol used for device identification and current negotiation, the signal states of the CC1 and CC2 pins can be flexibly adjusted by controlling the gate of the MOSFET through the charging management chip: when charging mode needs to be started, the chip controls the MOSFET to conduct, which can enhance the detection accuracy of the protocol signal of the CC pin and ensure the stability of the TYPEC protocol communication between the mobile phone and the external charger; when switching to discharging mode, the chip controls the MOSFET to cut off, which can quickly cut off the redundant signal path of the CC pin and avoid irrelevant signals from interfering with the power supply stability of the LDO circuit. This not only ensures the reliability of TYPEC protocol interaction, but also lays the hardware foundation for the intelligent switching of subsequent charging and discharging modes and prevents circuit malfunctions caused by uncontrolled CC pin signals.

[0040] Furthermore,

[0041] The charging mode trigger condition of the power management circuit is that the VDET detection signal is high, the VEN_A / VEN_B signal is active, and the pull-down signal of R53 is detected on the CC1 pin. At this time, the charging management chip turns on Q14 and Q15 to strengthen the detection of the TYPEC protocol signal on the CC1 and CC2 pins. At the same time, the charging voltage input to TYPEC2 is stepped down and regulated and then output to VBUS of TYPEC1 through the CHGCC1 / CHGCC2 pins to charge the mobile phone.

[0042] The power management circuit needs to meet three trigger conditions simultaneously to enter charging mode: First, the VDET detection signal output by the power matching circuit is high, indicating that the external charger is connected and supplying power normally; second, the VEN_A / VEN_B signal output by the power matching circuit is valid, indicating that the circuit has the enable condition to start charging; third, the CC1 pin of the TYPEC1 interface detects the pull-down signal of resistor R53, indicating that the mobile phone has a stable physical connection with the adapter. When all three conditions are met, the charging management chip will immediately perform two core actions: on the one hand, it turns on the N-channel MOSFETs Q14 and Q15, and strengthens the detection capability of the CC1 and CC2 pins for the TYPEC protocol signal through the conduction characteristics of the MOSFETs, ensuring that the protocol interaction is without deviation; on the other hand, it steps down and regulates the input external charging voltage received by TYPEC2, and then outputs it to the VBUS pin of the TYPEC1 interface through its own CHGCC1 / CHGCC2 pins, ultimately providing a stable charging voltage for the mobile phone.

[0043] This multi-condition triggered charging mode minimizes the risk of accidental charging and safety issues. First, multi-condition verification ensures that charging only begins under the complete scenario of "external power supply, circuit startup, and correct phone connection," preventing the risk of invalid power supply or circuit no-load due to a single condition being met, such as accidentally plugging in a phone charger without connecting the phone. Second, enhanced protocol detection using a conducting MOSFET accurately identifies the Type-C protocol versions of the charger and phone, such as PD and QC protocols, ensuring matching charging voltage and current and avoiding issues like low charging efficiency or device damage caused by protocol incompatibility. Finally, the step-down and voltage regulation process provides a suitable installation voltage for the device, filtering external power fluctuations and maintaining stable power supply to the LDO circuit and digital audio circuit during phone charging, achieving simultaneous "charging" and "anti-eavesdropping" functions.

[0044] Furthermore,

[0045] The power management circuit's discharge mode is when the VDET detection signal is low. The charging management chip cuts off MOSFETs Q14 and Q15, stopping the output of charging voltage to TYPEC1, but continues to output VBAT voltage to the LDO circuit, ensuring that the digital audio circuit continues to work and the anti-eavesdropping function is not interrupted.

[0046] The power management circuit switches to discharge mode when the VDET detection signal output by the power matching circuit is low, indicating that the external charger is not connected, the power supply is interrupted, or the power supply is abnormal. In this case, the adapter cannot obtain power from the outside and needs to switch to the mobile phone power supply mode. When VDET is detected to be low, the charging management chip performs two key operations: First, it controls the N-channel MOSFETs Q14 and Q15 to be cut off, completely cutting off the path of "the adapter outputting charging voltage to the mobile phone" to avoid power supply conflict between the adapter and the mobile phone; Second, it starts the path of "the mobile phone supplying power to the adapter"—the mobile phone inputs voltage to the power management circuit inside the adapter through the VBUS pin of the TYPEC1 interface in the dual TYPEC interface module. The power management circuit processes this voltage into VBAT voltage and continuously outputs it to the LDO circuit to ensure that the LDO circuit can supply power to the digital audio circuit normally without interrupting the anti-eavesdropping function.

[0047] The essence of the discharge mode is to "maintain the core anti-eavesdropping function by relying on the phone's power supply when there is no external charging." Its design solves the problem of "anti-eavesdropping failure in scenarios without external power" and avoids power supply logic disorder. First, when the external charger is disconnected (VDET low level), the adapter cannot obtain power from the TYPEC2 interface. At this time, it receives power from the phone through the TYPEC1 interface, providing a unique and stable power source for the LDO circuit and digital audio circuit. This ensures that the digital audio circuit can always take over the phone's audio input / output path, cutting off the direct connection between malicious programs and the microphone, and ensuring uninterrupted information security. Second, the charging management chip cuts off MOSFETs Q14 and Q15, preventing the adapter from simultaneously receiving power from the phone and outputting voltage back to the phone, avoiding the contradictory state of the phone both "powering" and "being charged," and reducing ineffective battery consumption. Finally, in this mode, only the low-power digital audio circuit and LDO circuit are powered, preventing excessive consumption of the phone's power and achieving a balance between "anti-eavesdropping security" and "phone battery life."

[0048] Furthermore,

[0049] The digital audio circuit also includes a digital audio chip and matching resistors R60, R61, R62, and R63. R60 is connected at one end to the VCMBUFR pin of the digital audio chip and at the other end to the MICP pin. R61 is connected at one end to the MICN pin and at the other end to VCMBUFL. R62 is connected in series with R60, with one end connected to the AUDIO pin of the digital audio chip and the other end grounded. R63 is connected in series with R61, with one end connected to the AUDIO pin of the digital audio chip and the other end grounded. All matching resistors work together to achieve impedance matching of the audio signal, preventing audio distortion caused by signal reflection.

[0050] If impedance mismatch occurs during audio signal transmission, signal reflection will occur, leading to audio distortion (such as call noise and unclear voice recording), affecting the normal audio functions of the mobile phone. The design of these four resistors precisely adjusts the impedance characteristics between the digital audio chip and the mobile phone's audio interface: on one hand, R60 and R61 directly perform impedance matching for the microphone input signals (MICP, MICN), ensuring that the audio signal from the mobile phone microphone can be transmitted to the digital audio chip completely and without reflection; on the other hand, R62 and R63, connected in series with R60 and R61 and grounded, further optimize signal voltage division, filter out minor interference signals, and avoid audio quality degradation caused by noise superposition. Ultimately, this achieves the effect of "preventing eavesdropping without affecting normal audio use": it cuts off the eavesdropping path of malicious programs through the digital audio circuit while ensuring the audio clarity of user calls, voice recording, and other functions, balancing security and practicality.

[0051] Furthermore,

[0052] The input filter capacitors of the LDO circuit include C43 and C44. After they are connected in parallel, one end is connected to the input terminal of the LDO chip and the other end is grounded. The VOUT terminal of the LDO chip is connected to the VBAT terminal of the digital audio chip.

[0053] The raw voltage output by the power management circuit may contain high-frequency noise or voltage ripple, especially during the switching between charging and discharging modes. If directly input to the LDO chip, this can cause fluctuations in the LDO output voltage, thus affecting the stable operation of the digital audio chip. However, by connecting C43 and C44 in parallel, the total capacitance increases, resulting in a wider filtering bandwidth. This more effectively filters out high-frequency noise and ripple from the raw voltage, providing a "clean" input voltage for the LDO chip. The LDO chip then performs low-dropout regulation, outputting a more accurate and less volatile fixed voltage directly to the digital audio chip. This design ensures a consistently stable power supply voltage for the digital audio chip, preventing issues such as chip crashes and audio path failures caused by voltage fluctuations. This guarantees the continuous and reliable operation of the anti-eavesdropping function. Simultaneously, a stable power supply reduces internal signal interference within the digital audio chip, improving the accuracy of audio signal processing.

[0054] It is understood that the above embodiments are merely exemplary implementations used to illustrate the principles of the present invention, and the present invention is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. An adapter for preventing mobile phone eavesdropping, characterized in that, The adapter body integrates a dual Type-C interface module, a power matching circuit, a power management circuit, an LDO circuit, and a digital audio circuit. The connection relationships and functions of each module are as follows: The dual TYPEC interface module includes a TYPEC1 interface and a TYPEC2 interface; the TYPEC1 interface is a male TYPEC connector used for physical connection with the mobile phone, transmitting the mobile phone's audio signals and receiving charging voltage; the TYPEC2 interface is a female TYPEC connector used for connection with an external charger to introduce external charging power. The input terminal of the power matching circuit is connected in series with the VBUS pin of the TYPEC2 interface, and the output terminal is connected to the signal input terminal of the power management circuit. The power matching circuit is used to detect the power supply status of the external charger. After filtering out power supply noise through the built-in current limiting resistor and filter capacitor, it outputs the VDET detection signal and VEN_A / VEN_B enable signal to the power management circuit. The power management circuit includes a charging management chip, whose signal input terminals are respectively connected to the VDET detection signal output terminal and the VEN_A / VEN_B enable signal output terminal of the power matching circuit, as well as the CC1 pin of the TYPEC1 interface and the CC2 pin of the TYPEC2 interface; its power input terminal is connected to the VBUS pin of the TYPEC2 interface, and its power output terminal is divided into two paths: one path is connected to the VBUS pin of the TYPEC1 interface, and the other path is connected to the input terminal of the LDO circuit; the power management circuit is used to intelligently switch between charging mode and discharging mode according to the VDET detection signal, the VEN_A / VEN_B enable signal, and the CC1 / CC2 pin signals, so as to provide charging voltage for the mobile phone and stable raw power for the LDO circuit; The LDO circuit includes a low dropout regulator, with its input terminal connected to the power output terminal of the power management circuit and its output terminal connected to the power supply terminal of the digital audio circuit. The LDO circuit is used to regulate the fluctuating voltage output by the power management circuit into a fixed voltage, providing a stable power supply to the digital audio circuit that is unaffected by the charging and discharging state. The digital audio circuit includes a digital audio chip, whose audio signal input terminal is connected to the Dp1 / Dn1 pins of the TYPEC1 interface, and its power supply terminal is connected to the output terminal of the LDO circuit. The digital audio circuit does not integrate independent speakers and microphones, but is only used to take over the audio input / output path of the mobile phone, cut off the direct connection between malicious programs and the mobile phone microphone, and achieve physical-level anti-eavesdropping.

2. The adapter for mobile phone eavesdropping prevention according to claim 1, characterized in that, The power management circuit also includes N-channel MOSFETs Q14 and Q15; The gates of MOSFETs Q14 and Q15 are both connected to the control terminal of the charging management chip. The sources of MOSFETs Q14 and Q15 are both grounded. The drain of MOSFET Q14 is connected to the CC1 pin of TYPEC1, and the drain of MOSFET Q15 is connected to the CC2 pin of TYPEC2.

3. The adapter for mobile phone anti-eavesdropping according to claim 2, characterized in that, The charging mode trigger condition of the power management circuit is that the VDET detection signal is high, the VEN_A / VEN_B signal is active, and the pull-down signal of R53 is detected on the CC1 pin. At this time, the charging management chip turns on Q14 and Q15 to strengthen the detection of the TYPEC protocol signal on the CC1 and CC2 pins. At the same time, the charging voltage input to TYPEC2 is stepped down and regulated and then output to VBUS of TYPEC1 through the CHGCC1 / CHGCC2 pins to charge the mobile phone.

4. The adapter for mobile phone anti-eavesdropping according to claim 2, characterized in that, The power management circuit's discharge mode is when the VDET detection signal is low. The charging management chip cuts off MOSFETs Q14 and Q15, stopping the output of charging voltage to TYPEC1, but continues to output VBAT voltage to the LDO circuit, ensuring that the digital audio circuit continues to work and the anti-eavesdropping function is not interrupted.

5. The adapter for mobile phone anti-eavesdropping according to claim 1, characterized in that, The digital audio circuit also includes a digital audio chip and matching resistors R60, R61, R62, and R63. R60 is connected at one end to the VCMBUFR pin of the digital audio chip and at the other end to the MICP pin. R61 is connected at one end to the MICN pin and at the other end to VCMBUFL. R62 is connected in series with R60, with one end connected to the AUDIO pin of the digital audio chip and the other end grounded. R63 is connected in series with R61, with one end connected to the AUDIO pin of the digital audio chip and the other end grounded. All matching resistors achieve impedance matching of the audio signal, preventing audio distortion caused by signal reflection.

6. The adapter for mobile phone anti-eavesdropping according to claim 1, characterized in that, The input filter capacitors of the LDO circuit include C43 and C44. After they are connected in parallel, one end is connected to the input terminal of the LDO chip and the other end is grounded. The VOUT terminal of the LDO chip is connected to the VBAT terminal of the digital audio chip.

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