Power adapter circuit based on high-voltage flyback power supply

Abstract

The utility model provides a power adapter circuit based on a high-voltage flyback power supply, which relates to the technical field of charging sockets and comprises an alternating-current input and rectification filtering unit, a flyback power supply driving unit, a transformer T1, an isolation type direct-current conversion unit, a double-path output direct-current conversion unit, a wireless charging unit and a USB (universal serial bus) charging unit. Isolated direct-current voltage is converted into two paths of different direct-current output voltage through a double-path output direct-current conversion unit, one path of direct-current output voltage is used for supplying power to a USB-C interface supporting PD fast charging, the other path of direct-current output voltage is used for carrying out 15W wireless fast charging on equipment supporting wireless charging, and PD full-power fast charging and 15W wireless fast charging supporting the USB-C interface at the same time are achieved. High conversion efficiency is realized through a high-voltage flyback power supply architecture, energy loss can be reduced, and the overall efficiency of the power adapter is improved. The isolated DC conversion unit isolates the output voltage from the input voltage, thereby effectively preventing electrical interference, and improving the safety of the charging process.

Description

Technical Field

[0001] The utility model relates to the technical field of charging sockets, in particular to a power adapter circuit based on a high-voltage flyback power supply. Background Art

[0002] In recent years, with the rapid development of electronic devices, users have higher and higher requirements for charging speed and convenience. Traditional power adapters have slow charging speed and single interfaces, unable to meet the charging needs of multiple devices. To solve these problems, USB Power Delivery (PD) fast charging technology and wireless charging technology have emerged as the times require.

[0003] USB PD fast charging technology provides higher voltage and current through the USB-C interface to achieve fast charging. Compared with the traditional USB charging method, PD fast charging can significantly shorten the charging time and improve the user experience. At the same time, wireless charging technology does not require a data cable connection, and users only need to place the device on the charging board to charge, greatly improving the charging convenience.

[0004] However, most of the existing power adapters only support a single charging technology, that is, either support USB PD fast charging or support wireless charging, and cannot meet the needs of users for both charging methods at the same time. Therefore, developing a power adapter that can support both USB-C PD fast charging and wireless fast charging is of great significance for meeting the growing charging needs of users and improving the user experience.

[0005] Therefore, it is necessary to improve the existing power adapter circuit to overcome the defects of the existing technology. Summary of the Utility Model

[0006] To overcome the problems existing in the related art, the purpose of the utility model is to provide a power adapter circuit based on a high-voltage flyback power supply to solve the problem that PD fast charging and wireless fast charging cannot be satisfied at the same time in the existing technology.

[0007] A power adapter circuit based on a high-voltage flyback power supply includes

[0008] An AC input and rectification and filtering unit, used to rectify and filter the AC input voltage and output a DC high voltage;

[0009] A flyback power supply driving unit, connected to the AC input and rectification and filtering unit, used to convert the DC high voltage output by the AC input and rectification and filtering unit into a high-frequency AC voltage;

[0010] A transformer T1, the primary side of the transformer T1 forms a loop with the AC input and rectification and filtering unit and the flyback power supply driving unit;

[0011] An isolated DC conversion unit forms a loop with the secondary side of the transformer T1 and is used to convert the high-frequency AC voltage into an isolated DC voltage;

[0012] A dual-output DC conversion unit is connected to the isolated DC conversion unit and is used to convert the isolated DC voltage into two different DC output voltages;

[0013] A wireless charging unit is connected to the isolated DC conversion unit and is used to wirelessly charge a device that supports wireless charging;

[0014] A USB charging unit is connected to the dual-output DC conversion unit and is used to charge a USB device. The USB charging unit includes a USB-C interface and a USB-A interface.

[0015] By subjecting the AC input voltage to multiple-level conversion, two different DC voltages are finally output and are respectively supplied to the USB charging unit and the wireless charging unit. It can support USB device charging and wireless charging simultaneously, meeting the user's needs for different charging methods, and has versatility and practicality.

[0016] Preferably, the AC input and rectification and filtering unit includes an AC input module, an EMI filtering module, and a rectification and filtering module that are connected in sequence;

[0017] The AC input module includes a live wire input terminal, a neutral wire input terminal, and a fuse F1 connected in series with the neutral wire input terminal;

[0018] The EMI filtering module sequentially includes a varistor RV1, a common-mode inductor LF1, an RC damping network, and a common-mode inductor LF2. The varistor RV1 is connected in parallel between the live wire input terminal and the neutral wire input terminal, and the two coil windings of the common-mode inductor LF1 are respectively connected in series with the live wire input terminal and the neutral wire input terminal;

[0019] The RC damping network includes a resonant capacitor CX1, a first resistor R1, a second resistor R2, a third resistor R3, and a fourth resistor R4. The resonant capacitor CX1 is connected in parallel between the live wire input terminal and the neutral wire input terminal. One ends of the first resistor R1, the second resistor R2, the third resistor R3, and the fourth resistor R4 are connected to each other. The other ends of the first resistor R1 and the second resistor R2 are connected to the neutral wire input terminal, and the other ends of the third resistor R3 and the fourth resistor R4 are connected to the live wire input terminal;

[0020] The two coil windings of the common-mode inductor LF2 are respectively connected in series with the live wire input terminal and the neutral wire input terminal;

[0021] The rectification and filtering module includes a bridge rectifier BD1, a first capacitor C1 and a second capacitor C10. The bridge rectifier BD1 is connected between the live wire input terminal and the neutral wire input terminal, and the first capacitor C1 and the second capacitor C10 are respectively connected in parallel at the output terminal of the bridge rectifier BD1.

[0022] By connecting the AC input module, the EMI filtering module and the rectification and filtering module in sequence, electromagnetic interference can be effectively suppressed, the stability and reliability of the circuit operation can be ensured, and the electromagnetic compatibility of the power adapter can be improved.

[0023] Preferably, the flyback power driving unit and the bridge rectifier BD1 form a flyback loop. The flyback power driving unit includes a MOS switch circuit, an RCD circuit, a startup circuit, and a power control chip U1. The power control chip U1 is provided with a GATE pin, a VDD pin, an FB pin, a PRT pin, and a CS pin;

[0024] The MOS switch circuit includes a MOS transistor Q1 and a third capacitor C9, and is used to control the on and off of the flyback loop. The drain of the MOS transistor Q1 is connected to the primary winding of the transformer T1, the source is grounded, the gate is connected to the GATE pin of the power control chip U1, the third capacitor C9 is connected in parallel between the source and the drain of the MOS transistor Q1, and a fifth resistor R15 is connected between the source of the MOS transistor Q1 and the ground.

[0025] The RCD circuit is connected in parallel at both ends of the primary winding of the transformer T1. The RCD circuit includes a fourth capacitor C2, a sixth resistor R6, and a first diode D1 connected in sequence. The positive electrode of the first diode D1 and the fourth capacitor C2 are connected in parallel at both ends of the primary winding of the transformer T1, and a seventh resistor R7 and an eighth resistor R8 are respectively connected in parallel at both ends of the fourth capacitor C2 and the sixth resistor R6;

[0026] A startup circuit is provided between the VDD pin of the power control chip U1 and the output terminal of the bridge rectifier BD1. Along the direction from the output terminal of the bridge rectifier BD1 to the VDD pin of the power control chip U1, the startup circuit includes a ninth resistor R5, a tenth resistor R5A, and an eleventh resistor R5B connected in series in sequence. A sixth capacitor C5 is bypassed and grounded between the VDD pin and the eleventh resistor R5B;

[0027] The PRT pin of the power control chip U1 is connected to a twelfth resistor R11 grounded, and the twelfth resistor R11 is used to set the operating frequency of the power control chip U1;

[0028] A drive circuit is provided between the GATE pin of the power control chip U1 and the gate of the MOS transistor Q1; the drive circuit includes a thirteenth resistor R13 and a fourteenth resistor R12 and a second diode D4 connected in parallel across the thirteenth resistor R13. One end of the thirteenth resistor R13 is connected to the GATE pin of the power control chip U1, and the other end is connected to the gate of the MOS transistor Q1. The negative electrode of the second diode D4 is connected between the GATE pin of the power control chip U1 and the thirteenth resistor R13, and the positive electrode of the second diode D4 is connected to the fourteenth resistor R12;

[0029] A fifteenth resistor R18 is connected between the CS pin of the power control chip U1 and the source of the MOS transistor Q1. A seventh capacitor C7 is bypass-connected to ground between the fifteenth resistor R18 and the CS pin of the power control chip U1. A sixteenth resistor R14 is also connected in parallel between the source and the gate of the MOS transistor Q1;

[0030] The FB pin of the power control chip U1 is connected to a primary-side optocoupler feedback circuit. The primary-side optocoupler feedback circuit includes a first optocoupler PC1A and an eighth capacitor C6. One end of the first optocoupler PC1A is connected to the FB pin of the power control chip U1, and the other end is grounded. The eighth capacitor C6 is connected in parallel across the first optocoupler PC1A.

[0031] An auxiliary coil is also provided on the primary side of the transformer T1. One end of the auxiliary coil is grounded, and the other end is connected to the VDD pin of the power control chip U1. A clamping circuit is connected between the auxiliary coil and the VDD pin of the power control chip U1. The clamping circuit includes a third diode D2, a ninth capacitor C3, and a seventeenth resistor R19. The positive electrode of the third diode D2 is connected to the auxiliary coil, and the negative electrode is connected to the VDD pin of the power control chip U1. One end of the seventeenth resistor R19 is connected to the positive electrode of the third diode D2, and the other end is connected to the ninth capacitor C3. The other end of the ninth capacitor C3 is connected to the negative electrode of the third diode D2.

[0032] Through the coordinated operation of the MOS switch circuit, the RCD circuit, the startup circuit, and the power control chip U1, the generation and control of high-frequency AC voltage are realized, providing a basis for subsequent voltage conversion.

[0033] Preferably, the isolated DC conversion unit includes a drive chip US1, a common-mode inductor LS1, the positive electrode of the 13V output terminal, and the signal ground. The dual-output DC conversion unit is connected to the positive electrode of the 13V output terminal and the signal ground. The drive chip US1 includes four D pins, two S pins, one VD pin, and one VCC pin;

[0034] One end of the secondary coil of the transformer T1 is connected to the four D pins and the VD pin of the driving chip US1, and the other end is connected to the two S pins and the VCC pin of the driving chip US1. The two S pins of the driving chip US1 are connected to the signal ground. An eighteenth resistor RS7 and a tenth capacitor CS7 are sequentially connected between the D pin and the S pin. An eleventh capacitor CS1 and a twelfth capacitor CS3 are also connected in parallel between the positive pole of the 13V output and the signal ground. The first winding of the common mode inductor LS1 is connected between the positive pole of the 13V output and the dual-output DC conversion unit, and the second winding is connected between the signal ground and the dual-output DC conversion unit.

[0035] Using components such as the driving chip US1 and the common mode inductor LS1, the high-frequency AC voltage is converted into an isolated 13V DC voltage, which not only ensures the stability of the output voltage, but also effectively isolates the input and output circuits, improving the safety of the circuit operation.

[0036] Preferably, the dual-output DC conversion unit includes a DC-DC buck control chip US51 and a common mode inductor LS2. The DC-DC buck control chip US51 includes two SW pins, two GND pins, one VIN pin, one CS pin, and one FB pin;

[0037] The VIN pin of the DC-DC buck control chip US51 is connected to the positive pole of the 13V output. The two GND pins are connected to the signal ground. The two SW pins are connected to each other. A nineteenth resistor RS56 and a thirteenth capacitor CS58 are connected in series between the VIN pin and the SW pin. A fourteenth capacitor CS51 and a fifteenth capacitor CS52 are connected in parallel between the positive pole of the 13V output and the signal ground. A twentieth resistor RS51 is connected in series between the CS pin and the signal ground;

[0038] The first winding of the common mode inductor LS52 is connected between the SW pin and the USB charging unit, and both ends of the second winding are connected to the signal ground;

[0039] There is an LS51 connected in series between the SW pin and the common-mode inductor LS52. A sixteenth capacitor CS43 and a twenty-first resistor RS52 are connected in parallel and in series between the common-mode inductors LS51 and then connected to the signal ground. A seventeenth capacitor CS54, a twenty-second resistor RS53, a twenty-third resistor RS54, a Y capacitor CS55, and an eighteenth capacitor CS56 are respectively connected in parallel between the inductor LS51 and the common-mode inductor LS52. One end of the seventeenth capacitor CS54 is connected between the inductor LS51 and the common-mode inductor LS52, and the other end is connected to the FB pin. One end of the twenty-second resistor RS53 is connected between the inductor LS51 and the common-mode inductor LS52, and the other end is connected to the twenty-third resistor RS54 and between the seventeenth capacitor CS54 and the FB pin. The other end of the twenty-third resistor RS54 is connected to the signal ground. One end of the Y capacitor CS55 is connected between the inductor LS51 and the common-mode inductor LS52, and the other end is connected to the signal ground. One end of the eighteenth capacitor CS56 is connected between the inductor LS51 and the common-mode inductor LS52, and the other end is connected to the signal ground.

[0040] Through the DC-DC buck control chip US51 and the common-mode inductor LS2, the 13V DC voltage is converted into two different DC output voltages to provide a suitable voltage for the USB charging unit, realizing the charging function for USB devices.

[0041] Preferably, it further includes a monitoring and protection unit. The monitoring and protection unit includes an optocoupler PC1B. One end of the optocoupler PC1B is connected to the positive pole of the 13V output, and the other end is connected to the signal ground. A twenty-fourth resistor RS1 is also connected between the optocoupler PC1B and the positive pole of the 13V output. A twenty-fifth resistor RS2 is connected in parallel across both ends of the optocoupler PC1B. A twenty-sixth resistor RS3, a nineteenth capacitor CS5, a twentieth capacitor CS6, and a twenty-seventh resistor RS4 are connected in series and in parallel across both ends of the optocoupler PC1B and the twenty-fourth resistor RS1. A twenty-eighth resistor RS5 is connected in parallel across both ends of the twentieth capacitor CS6 and the twenty-seventh resistor RS4. A twenty-ninth resistor RS6 is connected in parallel between the nineteenth capacitor CS5 and the twentieth capacitor CS6, and the other end of the twenty-ninth resistor RS6 is connected to the signal ground.

[0042] Through the optocoupler PC1B and components such as resistors and capacitors, the real-time monitoring of the circuit working state is realized, and the circuit is cut off in time when an abnormal situation occurs, effectively protecting the circuit safety and improving the reliability of the power adapter.

[0043] Preferably, the USB charging unit includes a USB interface control chip U52, a switching transistor Q51, a USB-A interface, and a USB-C interface;

[0044] The USB interface control chip includes a VPWR pin, a VFB pin, a GND pin, an ISP2 pin, a GD2 pin, a VBUSA pin, a DP2 pin, a DM2 pin, a DP1 pin, a DM1 pin, a CC1 pin, and a CC2 pin. The VPWR pin is connected to the first winding of the common-mode inductor LS52. The VFB pin is connected between the seventeenth capacitor CS54 and the FB pin of the DC-DC buck control chip US51. The GND pin is connected to the signal ground. The ISP2 pin is connected to a twenty-eighth resistor RS55, and the other end of the twenty-eighth resistor RS55 is connected to the signal ground. The GD2 pin is connected to the gate of the switching transistor Q51. The VBUSA pin is connected to the source of the switching transistor Q51. The drain of the switching transistor Q51 is connected to the first winding of the common-mode inductor LS52;

[0045] The USB-A interface includes a VBUS pin, a D- pin, and a D+ pin. The VBUS pin is connected to the source of the switching transistor Q51. The D- pin is connected to the DM2 pin of the USB interface control chip. The D+ pin is connected to the DP2 pin of the USB interface control chip;

[0046] The USB-C interface includes a VBUS-C pin, a D+ pin, a D- pin, a CC1 pin, and a CC2 pin. The VBUS-C pin is connected to the VBUS pin of the USB interface control chip. The D+ pin is connected to the DP1 pin of the USB interface control chip. The D- pin is connected to the DM1 pin of the USB interface control chip. The CC1 pin is connected to the CC1 pin of the USB interface control chip. The CC2 pin is connected to the CC2 pin of the USB interface control chip.

[0047] Through the USB interface control chip U52, the switching transistor Q51, and the USB-A and USB-C interfaces, the charging function for different types of USB devices is realized, and the USB interface control chip U52 controls and manages the charging process, improving the charging efficiency and safety.

[0048] The beneficial effects of the present utility model are:

[0049] The utility model provides a power adapter circuit based on a high-voltage flyback power supply, which includes an AC input and rectification and filtering unit, a flyback power supply driving unit, a transformer T1, an isolated DC conversion unit, a dual-output DC conversion unit, a wireless charging unit, and a USB charging unit. The isolated DC voltage is converted into two different DC output voltages through the dual-output DC conversion unit. One of them supplies power to a USB-C interface that supports PD fast charging, and the other performs 15W wireless fast charging for a device that supports wireless charging, realizing simultaneous support for PD full-power fast charging of the USB-C interface and 15W wireless fast charging. The high-voltage flyback power supply architecture is adopted to achieve high conversion efficiency, reduce energy loss, and improve the overall efficiency of the power adapter. The isolated DC conversion unit isolates the output voltage from the input voltage, effectively preventing electrical interference and improving the safety of the charging process. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 is the unit connection diagram of the power adapter circuit provided in the embodiment of the present application;

[0051] Figure 2 is the circuit schematic diagram of the power adapter circuit provided in the embodiment of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0052] The preferred embodiments of the present utility model will be described in more detail below with reference to the accompanying drawings. Although the preferred embodiments of the present utility model are shown in the drawings, it should be understood that the present utility model can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to make the present utility model more thorough and complete, and to fully convey the scope of the present utility model to those skilled in the art.

[0053] Embodiment 1

[0054] As Figure 1 - Figure 2 shown, this embodiment provides a power adapter circuit based on a high-voltage flyback power supply. The power adapter circuit based on a high-voltage flyback power supply includes:

[0055] An AC input and rectification and filtering unit, which is used to rectify and filter the AC input voltage and then output a DC high voltage;

[0056] A flyback power supply driving unit, connected to the AC input and rectification and filtering unit, which is used to convert the DC high voltage output by the AC input and rectification and filtering unit into a high-frequency AC voltage;

[0057] A transformer T1, the primary side of the transformer T1 forms a loop with the AC input and rectification and filtering unit and the flyback power supply driving unit;

[0058] An isolated DC conversion unit forms a loop with the secondary side of the transformer T1 and is used to convert the high-frequency AC voltage into an isolated DC voltage;

[0059] A dual-output DC conversion unit is connected to the isolated DC conversion unit and is used to convert the isolated DC voltage into two different DC output voltages;

[0060] A wireless charging unit is connected to the isolated DC conversion unit and is used to wirelessly charge a device that supports wireless charging;

[0061] A USB charging unit is connected to the dual-output DC conversion unit and is used to charge a USB device. The USB charging unit includes a USB-C interface and a USB-A interface.

[0062] By subjecting the AC input voltage to multiple-stage conversion, two different DC voltages are finally output and are respectively supplied to the USB charging unit and the wireless charging unit. It can support USB device charging and wireless charging simultaneously, meeting the user's needs for different charging methods, and has versatility and practicality.

[0063] Furthermore, the AC input and rectification and filtering unit includes an AC input module, an EMI filtering module, and a rectification and filtering module connected in sequence;

[0064] The AC input module includes a live wire input terminal, a neutral wire input terminal, and a fuse F1 connected in series with the neutral wire input terminal;

[0065] The EMI filtering module sequentially includes a varistor RV1, a common-mode inductor LF1, an RC damping network, and a common-mode inductor LF2. The varistor RV1 is connected in parallel between the live wire input terminal and the neutral wire input terminal, and the two coil windings of the common-mode inductor LF1 are respectively connected in series with the live wire input terminal and the neutral wire input terminal;

[0066] The RC damping network includes a resonant capacitor CX1, a first resistor R1, a second resistor R2, a third resistor R3, and a fourth resistor R4. The resonant capacitor CX1 is connected in parallel between the live wire input terminal and the neutral wire input terminal. One ends of the first resistor R1, the second resistor R2, the third resistor R3, and the fourth resistor R4 are connected to each other. The other ends of the first resistor R1 and the second resistor R2 are connected to the neutral wire input terminal, and the other ends of the third resistor R3 and the fourth resistor R4 are connected to the live wire input terminal;

[0067] The two coil windings of the common-mode inductor LF2 are respectively connected in series with the live wire input terminal and the neutral wire input terminal;

[0068] The rectifying and filtering module includes a bridge rectifier BD1, a first capacitor C1, and a second capacitor C10. The bridge rectifier BD1 is connected between the live wire input terminal and the neutral wire input terminal, and the first capacitor C1 and the second capacitor C10 are respectively connected in parallel to the output terminal of the bridge rectifier BD1.

[0069] By sequentially connecting the AC input module, the EMI filtering module, and the rectifying and filtering module, electromagnetic interference can be effectively suppressed, the stability and reliability of the circuit operation can be ensured, and the electromagnetic compatibility of the power adapter can be improved.

[0070] Furthermore, the flyback power driving unit and the bridge rectifier BD1 form a flyback circuit. The flyback power driving unit includes a MOS switch circuit, an RCD circuit, a startup circuit, and a power control chip U1. The power control chip U1 is provided with a GATE pin, a VDD pin, an FB pin, a PRT pin, and a CS pin;

[0071] The MOS switch circuit includes a MOS transistor Q1 and a third capacitor C9, and is used to control the on / off of the flyback circuit. The drain of the MOS transistor Q1 is connected to the primary winding of the transformer T1, the source is grounded, the gate is connected to the GATE pin of the power control chip U1, the third capacitor C9 is connected in parallel between the source and the drain of the MOS transistor Q1, and a fifth resistor R15 is connected between the source of the MOS transistor Q1 and the ground.

[0072] The RCD circuit is connected in parallel across the two ends of the primary winding of the transformer T1. The RCD circuit includes a fourth capacitor C2, a sixth resistor R6, and a first diode D1 connected in sequence. The positive electrode of the first diode D1 and the fourth capacitor C2 are connected in parallel across the two ends of the primary winding of the transformer T1, and a seventh resistor R7 and an eighth resistor R8 are respectively connected in parallel across the two ends of the fourth capacitor C2 and the sixth resistor R6;

[0073] A startup circuit is provided between the VDD pin of the power control chip U1 and the output terminal of the bridge rectifier BD1. Along the direction from the output terminal of the bridge rectifier BD1 to the VDD pin of the power control chip U1, the startup circuit includes a ninth resistor R5, a tenth resistor R5A, and an eleventh resistor R5B connected in series in sequence. A sixth capacitor C5 is bypass-connected to the ground between the VDD pin and the eleventh resistor R5B;

[0074] The PRT pin of the power control chip U1 is connected to a twelfth resistor R11 grounded, and the twelfth resistor R11 is used to set the operating frequency of the power control chip U1;

[0075] A drive circuit is provided between the GATE pin of the power control chip U1 and the gate of the MOS transistor Q1; the drive circuit includes a thirteenth resistor R13 and a fourteenth resistor R12 and a second diode D4 connected in parallel across the thirteenth resistor R13. One end of the thirteenth resistor R13 is connected to the GATE pin of the power control chip U1, and the other end is connected to the gate of the MOS transistor Q1. The negative electrode of the second diode D4 is connected between the GATE pin of the power control chip U1 and the thirteenth resistor R13, and the positive electrode of the second diode D4 is connected to the fourteenth resistor R12;

[0076] A fifteenth resistor R18 is connected between the CS pin of the power control chip U1 and the source of the MOS transistor Q1. A seventh capacitor C7 is bypass-connected to ground between the fifteenth resistor R18 and the CS pin of the power control chip U1. A sixteenth resistor R14 is also connected in parallel between the source and the gate of the MOS transistor Q1;

[0077] The FB pin of the power control chip U1 is connected to a primary-side optocoupler feedback circuit. The primary-side optocoupler feedback circuit includes a first optocoupler PC1A and an eighth capacitor C6. One end of the first optocoupler PC1A is connected to the FB pin of the power control chip U1, and the other end is grounded. The eighth capacitor C6 is connected in parallel across the first optocoupler PC1A.

[0078] An auxiliary coil is also provided on the primary side of the transformer T1. One end of the auxiliary coil is grounded, and the other end is connected to the VDD pin of the power control chip U1. A clamping circuit is connected between the auxiliary coil and the VDD pin of the power control chip U1. The clamping circuit includes a third diode D2, a ninth capacitor C3, and a seventeenth resistor R19. The positive electrode of the third diode D2 is connected to the auxiliary coil, and the negative electrode is connected to the VDD pin of the power control chip U1. One end of the seventeenth resistor R19 is connected to the positive electrode of the third diode D2, and the other end is connected to the ninth capacitor C3. The other end of the ninth capacitor C3 is connected to the negative electrode of the third diode D2.

[0079] Through the coordinated operation of the MOS switch circuit, the RCD circuit, the startup circuit, and the power control chip U1, the generation and control of high-frequency AC voltage are achieved, providing a basis for subsequent voltage conversion.

[0080] Preferably, the isolated DC conversion unit includes a drive chip US1, a common-mode inductor LS1, the positive electrode of the 13V output terminal, and the signal ground. The dual-output DC conversion unit is connected to the positive electrode of the 13V output terminal and the signal ground. The drive chip US1 includes four D pins, two S pins, one VD pin, and one VCC pin;

[0081] One end of the secondary coil of the transformer T1 is connected to the four D pins and the VD pin of the driving chip US1, and the other end is connected to the two S pins and the VCC pin of the driving chip US1. The two S pins of the driving chip US1 are connected to the signal ground. An eighteenth resistor RS7 and a tenth capacitor CS7 are sequentially connected between the D pin and the S pin. An eleventh capacitor CS1 and a twelfth capacitor CS3 are also connected in parallel between the positive pole of the 13V output terminal and the signal ground. The first winding of the common mode inductor LS1 is connected between the positive pole of the 13V output terminal and the dual-output DC conversion unit, and the second winding is connected between the signal ground and the dual-output DC conversion unit.

[0082] Using components such as the driving chip US1 and the common mode inductor LS1, the high-frequency AC voltage is converted into an isolated 13V DC voltage, which not only ensures the stability of the output voltage, but also effectively isolates the input and output circuits, improving the safety of the circuit operation.

[0083] Furthermore, the dual-output DC conversion unit includes a DC-DC buck control chip US51 and a common mode inductor LS2. The DC-DC buck control chip US51 includes two SW pins, two GND pins, one VIN pin, one CS pin, and one FB pin;

[0084] The VIN pin of the DC-DC buck control chip US51 is connected to the positive pole of the 13V output terminal, the two GND pins are connected to the signal ground, the two SW pins are connected to each other, and a nineteenth resistor RS56 and a thirteenth capacitor CS58 are connected in series between the VIN pin and the SW pin; a fourteenth capacitor CS51 and a fifteenth capacitor CS52 are connected in parallel between the positive pole of the 13V output terminal and the signal ground; a twentieth resistor RS51 is connected in series between the CS pin and the signal ground;

[0085] The first winding of the common mode inductor LS52 is connected between the SW pin and the USB charging unit, and both ends of the second winding are connected to the signal ground;

[0086] There is an inductor LS51 connected in series between the SW pin and the common-mode inductor LS52. A sixteenth capacitor CS43 and a twenty-first resistor RS52 are connected in series and bypassed between the common-mode inductors LS51 and connected to the signal ground. A seventeenth capacitor CS54, a twenty-second resistor RS53, a twenty-third resistor RS54, a Y capacitor CS55, and an eighteenth capacitor CS56 are respectively connected in parallel between the inductor LS51 and the common-mode inductor LS52. One end of the seventeenth capacitor CS54 is connected between the inductor LS51 and the common-mode inductor LS52, and the other end is connected to the FB pin. One end of the twenty-second resistor RS53 is connected between the inductor LS51 and the common-mode inductor LS52, and the other end is connected to the twenty-third resistor RS54 and between the seventeenth capacitor CS54 and the FB pin. The other end of the twenty-third resistor RS54 is connected to the signal ground. One end of the Y capacitor CS55 is connected between the inductor LS51 and the common-mode inductor LS52, and the other end is connected to the signal ground. One end of the eighteenth capacitor CS56 is connected between the inductor LS51 and the common-mode inductor LS52, and the other end is connected to the signal ground.

[0087] Through the DC-DC buck control chip US51 and the common-mode inductor LS2, the 13V DC voltage is converted into two different DC output voltages to provide a suitable voltage for the USB charging unit, realizing the charging function for USB devices.

[0088] Furthermore, it also includes a monitoring and protection unit. The monitoring and protection unit includes an optocoupler PC1B. One end of the optocoupler PC1B is connected to the positive pole of the 13V output, and the other end is connected to the signal ground. A twenty-fourth resistor RS1 is also connected between the optocoupler PC1B and the positive pole of the 13V output. A twenty-fifth resistor RS2 is connected in parallel across both ends of the optocoupler PC1B. A twenty-sixth resistor RS3, a nineteenth capacitor CS5, a twentieth capacitor CS6, and a twenty-seventh resistor RS4 are connected in sequence and in parallel across both ends of the optocoupler PC1B and the twenty-fourth resistor RS1. A twenty-eighth resistor RS5 is connected in parallel across both ends of the twentieth capacitor CS6 and the twenty-seventh resistor RS4. A twenty-ninth resistor RS6 is connected in parallel between the nineteenth capacitor CS5 and the twentieth capacitor CS6, and the other end of the twenty-ninth resistor RS6 is connected to the signal ground.

[0089] Through the optocoupler PC1B and components such as resistors and capacitors, the real-time monitoring of the circuit working state is realized, and the circuit is cut off in time when an abnormal situation occurs, effectively protecting the circuit safety and improving the reliability of the power adapter.

[0090] Furthermore, the USB charging unit includes a USB interface control chip U52, a switching transistor Q51, a USB-A interface, and a USB-C interface;

[0091] The USB interface control chip includes a VPWR pin, a VFB pin, a GND pin, an ISP2 pin, a GD2 pin, a VBUSA pin, a DP2 pin, a DM2 pin, a DP1 pin, a DM1 pin, a CC1 pin, a CC2 pin, and a VBUS pin. The VPWR pin is connected to the first winding of the common-mode inductor LS52. The VFB pin is connected between the seventeenth capacitor CS54 and the FB pin of the DC-DC buck control chip US51. The GND pin is connected to the signal ground. The ISP2 pin is connected to a twenty-eighth resistor RS55, and the other end of the twenty-eighth resistor RS55 is connected to the signal ground. The GD2 pin is connected to the gate of the switching transistor Q51. The VBUSA pin is connected to the source of the switching transistor Q51. The drain of the switching transistor Q51 is connected to the first winding of the common-mode inductor LS52;

[0092] The USB-A interface includes a VBUS pin, a D- pin, and a D+ pin. The VBUS pin is connected to the source of the switching transistor Q51. The D- pin is connected to the DM2 pin of the USB interface control chip. The D+ pin is connected to the DP2 pin of the USB interface control chip;

[0093] The USB-C interface includes a VBUS-C pin, a D+ pin, a D- pin, a CC1 pin, and a CC2 pin. The VBUS-C pin is connected to the VBUS pin of the USB interface control chip. The D+ pin is connected to the DP1 pin of the USB interface control chip. The D- pin is connected to the DM1 pin of the USB interface control chip. The CC1 pin is connected to the CC1 pin of the USB interface control chip. The CC2 pin is connected to the CC2 pin of the USB interface control chip.

[0094] Through the USB interface control chip U52, the switching transistor Q51, and the USB-A and USB-C interfaces, the charging function for different types of USB devices is realized, and the USB interface control chip U52 controls and manages the charging process, improving the charging efficiency and safety.

[0095] Specifically, the power adapter circuit based on the high-voltage flyback power supply in this embodiment includes:

[0096] I. AC input and rectification and filtering unit: It includes an AC input module, an EMI filtering module, and a rectification and filtering module, which are used to rectify and filter the AC input voltage.

[0097] AC input module: It includes a live wire input terminal, a neutral wire input terminal, and a fuse F1 connected in series with the neutral wire input terminal, which is used for preliminary overcurrent protection.

[0098] EMI Filter Module: It includes a varistor RV1, a common-mode inductor LF1, an RC damping network, and a common-mode inductor LF2, which are used to suppress electromagnetic interference and improve electromagnetic compatibility. The RC damping network includes a resonant capacitor CX1 and multiple resistors (R1, R2, R3, R4), which are used to absorb high-frequency oscillations in the circuit.

[0099] Rectifier Filter Module: It includes a bridge rectifier BD1, a first capacitor C1, and a second capacitor C10, which convert the AC voltage into a DC voltage, filter it, and output a smooth DC high voltage.

[0100] II. Flyback Power Drive Unit: It is connected to the AC input and the rectifier filter unit, and converts the DC high voltage into a high-frequency AC voltage. It includes a MOS switch circuit, an RCD circuit, a startup circuit, and a power control chip U1.

[0101] MOS Switch Circuit: It includes a MOS transistor Q1 and a third capacitor C9, which is controlled by the GATE pin of the power control chip U1, and is used to control the on and off of the flyback circuit, generating high-frequency oscillations.

[0102] RCD Circuit: It includes a fourth capacitor C2, a sixth resistor R6, and a first diode D1, which is connected in parallel with the primary winding of the transformer T1, and is used to absorb the spike voltage generated when the MOS transistor Q1 turns off, protecting the circuit safety.

[0103] Startup Circuit: It provides the voltage required for startup for the power control chip U1, and includes a ninth resistor R5, a tenth resistor R5A, an eleventh resistor R5B, and a sixth capacitor C5.

[0104] Power Control Chip U1: It controls the switching frequency and duty cycle of the MOS transistor Q1, realizes the regulation of the output voltage, and provides various protection functions.

[0105] III. Transformer T1: Its primary side forms a loop with the AC input, the rectifier filter unit, and the flyback power drive unit, and its secondary side is connected to the isolated DC conversion unit, which is used to realize voltage conversion and electrical isolation.

[0106] IV. Isolated DC Conversion Unit: It forms a loop with the secondary side of the transformer T1, and converts the high-frequency AC voltage into an isolated 13V DC voltage. It includes components such as a drive chip US1 and a common-mode inductor LS1.

[0107] Drive Chip US1: It controls the direction of current flow and realizes the conversion from AC to DC.

[0108] V. Dual-Output DC Conversion Unit: It is connected to the isolated DC conversion unit, and converts the 13V DC voltage into two different DC output voltages (such as 5V and 9V), which supply power to the USB charging unit and the wireless charging unit respectively.

[0109] It includes a DC-DC buck control chip US51 and a common-mode inductor LS2.

[0110] DC-DC buck control chip US51: By adjusting the output voltage, it provides stable 5V and 9V DC outputs.

[0111] VI. Wireless charging unit: Connected to the isolated DC conversion unit, it receives a 13V DC voltage and converts it into an AC voltage that meets the wireless charging standard to perform 15W wireless fast charging for devices that support wireless charging.

[0112] VII. USB charging unit: Connected to the dual-output DC conversion unit, it receives a 5V DC voltage and charges USB devices through the USB-C interface and the USB-A interface. It includes a USB interface control chip U52 and a switching transistor Q51.

[0113] USB interface control chip U52: Supports the USB PD fast charging protocol and can intelligently adjust the output voltage and current according to the charging requirements of the connected device to achieve fast and safe charging.

[0114] Working principle:

[0115] The AC input voltage passes through the AC input and rectification and filtering unit and is converted into a high DC voltage. The flyback power supply driving unit controls the MOS transistor Q1 to conduct and turn off periodically to generate a high-frequency AC voltage, which is applied to the primary side of the transformer T1. The transformer T1 couples the high-frequency AC voltage to the secondary side and performs voltage conversion. The isolated DC conversion unit converts the high-frequency AC voltage on the secondary side into an isolated 13V DC voltage. The dual-output DC conversion unit converts the 13V DC voltage into two different DC output voltages, one for the USB charging unit and the other for the wireless charging unit. The USB charging unit charges USB devices through the USB-C interface and the USB-A interface, supports the USB PD fast charging protocol, and can intelligently adjust the output voltage and current according to the charging requirements of the connected device. The wireless charging unit converts the 13V DC voltage into an AC voltage that meets the wireless charging standard to perform 15W wireless fast charging for devices that support wireless charging.

[0116] The power adapter circuit based on the high-voltage flyback power supply provided in this embodiment can charge a USB-C device that supports PD fast charging, a common USB device, and a device that supports wireless charging simultaneously, meeting the diverse charging needs of users. Adopting the high-voltage flyback power supply architecture, it has high conversion efficiency, can reduce energy loss, and improve the overall efficiency of the power adapter. The isolated DC conversion unit isolates the output voltage from the input voltage, effectively preventing electrical interference and improving the safety of the charging process. At the same time, the circuit also includes various protection circuits, such as overcurrent protection and overvoltage protection, to ensure the safety and reliability of the charging process. With the integrated wireless charging function, users can charge their devices by simply placing them in the charging area without plugging and unplugging the data cable, enhancing the convenience of charging.

[0117] Unless otherwise specifically stated, the relative arrangements of components and steps, numerical expressions, and values set forth in these embodiments do not limit the scope of the present application. In all examples shown and discussed herein, any specific value should be construed as merely exemplary and not as a limitation. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that like reference numerals and letters denote like items in the following figures, and thus, once an item is defined in one figure, further discussion thereof is not required in subsequent figures.

[0118] In addition, it should be noted that the use of terms such as "first" and "second" is only for the convenience of distinction. Without additional statements, the above terms have no special meanings and thus should not be construed as limiting the protection scope of the present application.

[0119] The above are only the preferred embodiments of the present utility model and are not used to limit the present utility model. For those skilled in the art, the present utility model can have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present utility model shall be included within the protection scope of the present utility model.

Claims

1. A power adapter circuit based on a high-voltage flyback power supply, characterized in that, Comprising: An AC input and rectification and filtering unit, configured to rectify and filter an AC input voltage and output a high DC voltage; A flyback power supply driving unit, connected to the AC input and rectification and filtering unit, configured to convert the high DC voltage output by the AC input and rectification and filtering unit into a high-frequency AC voltage; A transformer T1, a primary side of the transformer T1 forming a loop with the AC input and rectification and filtering unit and the flyback power supply driving unit; An isolated DC conversion unit, forming a loop with a secondary side of the transformer T1, configured to convert the high-frequency AC voltage into an isolated DC voltage; A dual-output DC conversion unit, connected to the isolated DC conversion unit, configured to convert the isolated DC voltage into two different DC output voltages; A wireless charging unit, connected to the isolated DC conversion unit, configured to perform wireless charging for a device supporting wireless charging; A USB charging unit, connected to the dual-output DC conversion unit, configured to charge a USB device, and the USB charging unit includes a USB-C interface and a USB-A interface.

2. The power adapter circuit based on a high-voltage flyback power supply according to claim 1, wherein: The AC input and rectification and filtering unit includes an AC input module, an EMI filtering module, and a rectification and filtering module connected in sequence; The AC input module includes a live wire input terminal, a neutral wire input terminal, and a fuse F1 connected in series with the neutral wire input terminal; The EMI filtering module sequentially includes a varistor RV1, a common-mode inductor LF1, an RC damping network, and a common-mode inductor LF2. The varistor RV1 is connected in parallel between the live wire input terminal and the neutral wire input terminal. Two coil windings of the common-mode inductor LF1 are respectively connected in series with the live wire input terminal and the neutral wire input terminal; The RC damping network includes a resonant capacitor CX1, a first resistor R1, a second resistor R2, a third resistor R3, and a fourth resistor R4. The resonant capacitor CX1 is connected in parallel between the live wire input terminal and the neutral wire input terminal. One ends of the first resistor R1, the second resistor R2, the third resistor R3, and the fourth resistor R4 are connected to each other. The other ends of the first resistor R1 and the second resistor R2 are connected to the neutral wire input terminal. The other ends of the third resistor R3 and the fourth resistor R4 are connected to the live wire input terminal; Two coil windings of the common-mode inductor LF2 are respectively connected in series with the live wire input terminal and the neutral wire input terminal; The rectification and filtering module includes a bridge rectifier BD1, a first capacitor C1, and a second capacitor C10. The bridge rectifier BD1 is connected between the live wire input terminal and the neutral wire input terminal. The first capacitor C1 and the second capacitor C10 are respectively connected in parallel to an output terminal of the bridge rectifier BD1.

3. The power adapter circuit based on a high-voltage flyback power supply according to claim 2, wherein: The flyback power supply driving unit and the bridge rectifier BD1 form a flyback circuit. The flyback power supply driving unit includes a MOS switch circuit, an RCD circuit, a startup circuit, and a power control chip U1. The power control chip U1 is provided with a GATE pin, a VDD pin, an FB pin, a PRT pin, and a CS pin; The MOS switch circuit includes a MOS transistor Q1 and a third capacitor C9, and is used to control the on / off of the flyback circuit. The drain of the MOS transistor Q1 is connected to the primary winding of the transformer T1, the source is grounded, the gate is connected to the GATE pin of the power control chip U1. The third capacitor C9 is connected in parallel between the source and the drain of the MOS transistor Q1. A fifth resistor R15 is connected between the source of the MOS transistor Q1 and the ground; Both ends of the primary winding of the transformer T1 are connected in parallel with the RCD circuit. The RCD circuit includes a fourth capacitor C2, a sixth resistor R6, and a first diode D1 connected in sequence. The positive electrode of the first diode D1 and the fourth capacitor C2 are connected in parallel between both ends of the primary winding of the transformer T1. A seventh resistor R7 and an eighth resistor R8 are respectively connected in parallel at both ends of the fourth capacitor C2 and the sixth resistor R6; A startup circuit is provided between the VDD pin of the power control chip U1 and the output end of the bridge rectifier BD1. Along the direction from the output end of the bridge rectifier BD1 to the VDD pin of the power control chip U1, the startup circuit includes a ninth resistor R5, a tenth resistor R5A, and an eleventh resistor R5B connected in series in sequence. A sixth capacitor C5 is bypass-connected to the ground between the VDD pin and the eleventh resistor R5B; The PRT pin of the power control chip U1 is connected to a twelfth resistor R11 grounded, and the twelfth resistor R11 is used to set the operating frequency of the power control chip U1; A driving circuit is provided between the GATE pin of the power control chip U1 and the gate of the MOS transistor Q1. The driving circuit includes a thirteenth resistor R13 and a fourteenth resistor R12 and a second diode D4 connected in parallel at both ends of the thirteenth resistor R13. One end of the thirteenth resistor R13 is connected to the GATE pin of the power control chip U1, and the other end is connected to the gate of the MOS transistor Q1. The negative electrode of the second diode D4 is connected between the GATE pin of the power control chip U1 and the thirteenth resistor R13, and the positive electrode of the second diode D4 is connected to the fourteenth resistor R12; A fifteenth resistor R18 is connected between the CS pin of the power control chip U1 and the source of the MOS transistor Q1. A seventh capacitor C7 is bypass-connected to the ground between the fifteenth resistor R18 and the CS pin of the power control chip U1. A sixteenth resistor R14 is also connected in parallel between the source and the gate of the MOS transistor Q1; The FB pin of the power control chip U1 is connected to a primary-side optocoupler feedback circuit. The primary-side optocoupler feedback circuit includes a first optocoupler PC1A and an eighth capacitor C6. One end of the first optocoupler PC1A is connected to the FB pin of the power control chip U1, and the other end is grounded. The eighth capacitor C6 is connected in parallel across the two ends of the first optocoupler PC1A; An auxiliary coil is also provided on the primary side of the transformer T1. One end of the auxiliary coil is grounded, and the other end is connected to the VDD pin of the power control chip U1. A clamping circuit is connected between the auxiliary coil and the VDD pin of the power control chip U1. The clamping circuit includes a third diode D2, a ninth capacitor C3, and a seventeenth resistor R19. The positive electrode of the third diode D2 is connected to the auxiliary coil, and the negative electrode is connected to the VDD pin of the power control chip U1. One end of the seventeenth resistor R19 is connected to the positive electrode of the third diode D2, and the other end is connected to the ninth capacitor C3. The other end of the ninth capacitor C3 is connected to the negative electrode of the third diode D2.

4. The power adapter circuit based on a high-voltage flyback power supply according to claim 3, wherein: The isolated DC conversion unit includes a drive chip US1, a common-mode inductor LS1, the positive electrode of the 13V output terminal, and a signal ground. The dual-output DC conversion unit is connected to the positive electrode of the 13V output terminal and the signal ground. The drive chip US1 includes four D pins, two S pins, one VD pin, and one VCC pin; One end of the secondary-side coil of the transformer T1 is connected to the four D pins and the VD pin of the drive chip US1, and the other end is connected to the two S pins and the VCC pin of the drive chip US1. The two S pins of the drive chip US1 are connected to the signal ground. An eighteenth resistor RS7 and a tenth capacitor CS7 are sequentially connected between the D pin and the S pin. An eleventh capacitor CS1 and a twelfth capacitor CS3 are also connected in parallel between the positive electrode of the 13V output terminal and the signal ground. The first winding of the common-mode inductor LS1 is connected between the positive electrode of the 13V output terminal and the dual-output DC conversion unit, and the second winding is connected between the signal ground and the dual-output DC conversion unit.

5. The power adapter circuit based on a high-voltage flyback power supply according to claim 4, wherein: The dual-output DC conversion unit includes a DC-DC buck control chip US51 and a common-mode inductor LS2. The DC-DC buck control chip US51 includes two SW pins, two GND pins, one VIN pin, one CS pin, and one FB pin; The VIN pin of the DC-DC buck control chip US51 is connected to the positive pole of the 13V output. The two GND pins are connected to the signal ground. The two SW pins are connected to each other. A nineteenth resistor RS56 and a thirteenth capacitor CS58 are connected in series between the VIN pin and the SW pin. A fourteenth capacitor CS51 and a fifteenth capacitor CS52 are connected in parallel between the positive pole of the 13V output and the signal ground. A twentieth resistor RS51 is connected in series between the CS pin and the signal ground. The first winding of the common-mode inductor LS52 is connected between the SW pin and the USB charging unit, and both ends of the second winding are connected to the signal ground. An inductor LS51 is connected in series between the SW pin and the common-mode inductor LS52. A sixteenth capacitor CS43 and a twenty-first resistor RS52 are connected in series in parallel between the common-mode inductors LS51 and connected to the signal ground. A seventeenth capacitor CS54, a twenty-second resistor RS53, a twenty-third resistor RS54, a Y capacitor CS55, and an eighteenth capacitor CS56 are respectively connected in parallel between the inductor LS51 and the common-mode inductor LS52. One end of the seventeenth capacitor CS54 is connected between the inductor LS51 and the common-mode inductor LS52, and the other end is connected to the FB pin. One end of the twenty-second resistor RS53 is connected between the inductor LS51 and the common-mode inductor LS52, and the other end is connected to the twenty-third resistor RS54 and between the seventeenth capacitor CS54 and the FB pin. The other end of the twenty-third resistor RS54 is connected to the signal ground. One end of the Y capacitor CS55 is connected between the inductor LS51 and the common-mode inductor LS52, and the other end is connected to the signal ground. One end of the eighteenth capacitor CS56 is connected between the inductor LS51 and the common-mode inductor LS52, and the other end is connected to the signal ground.

6. The power adapter circuit based on a high-voltage flyback power supply according to claim 5, wherein: It further includes a monitoring and protection unit. The monitoring and protection unit includes an optocoupler PC1B. One end of the optocoupler PC1B is connected to the positive pole of the 13V output, and the other end is connected to the signal ground. A twenty-fourth resistor RS1 is also connected between the optocoupler PC1B and the positive pole of the 13V output. A twenty-fifth resistor RS2 is connected in parallel across both ends of the optocoupler PC1B. A twenty-sixth resistor RS3, a nineteenth capacitor CS5, a twentieth capacitor CS6, and a twenty-seventh resistor RS4 are connected in series and in parallel across both ends of the optocoupler PC1B and the twenty-fourth resistor RS1. A twenty-eighth resistor RS5 is connected in parallel across both ends of the twentieth capacitor CS6 and the twenty-seventh resistor RS4. A twenty-ninth resistor RS6 is connected in parallel between the nineteenth capacitor CS5 and the twentieth capacitor CS6, and the other end of the twenty-ninth resistor RS6 is connected to the signal ground.

7. The power adapter circuit based on a high-voltage flyback power supply according to claim 6, wherein: The USB charging unit includes a USB interface control chip U52, a switching transistor Q51, a USB-A interface, and a USB-C interface; The USB interface control chip includes a VPWR pin, a VFB pin, a GND pin, an ISP2 pin, a GD2 pin, a VBUSA pin, a DP2 pin, a DM2 pin, a DP1 pin, a DM1 pin, a CC1 pin, a CC2 pin, and a VBUS pin. The VPWR pin is connected to the first winding of the common-mode inductor LS52. The VFB pin is connected between the seventeenth capacitor CS54 and the FB pin of the DC-DC buck control chip US51. The GND pin is connected to the signal ground. The ISP2 pin is connected to a twenty-eighth resistor RS55, and the other end of the twenty-eighth resistor RS55 is connected to the signal ground. The GD2 pin is connected to the gate of the switching transistor Q51. The VBUSA pin is connected to the source of the switching transistor Q51. The drain of the switching transistor Q51 is connected to the first winding of the common-mode inductor LS52; The USB-A interface includes a VBUS pin, a D- pin, and a D+ pin. The VBUS pin is connected to the source of the switching transistor Q51. The D- pin is connected to the DM2 pin of the USB interface control chip. The D+ pin is connected to the DP2 pin of the USB interface control chip; The USB-C interface includes a VBUS-C pin, a D+ pin, a D- pin, a CC1 pin, and a CC2 pin. The VBUS-C pin is connected to the VBUS pin of the USB interface control chip. The D+ pin is connected to the DP1 pin of the USB interface control chip. The D- pin is connected to the DM1 pin of the USB interface control chip. The CC1 pin is connected to the CC1 pin of the USB interface control chip. The CC2 pin is connected to the CC2 pin of the USB interface control chip.

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