A power supply circuit and a power adapter for achieving surge and electrostatic protection

Abstract

The utility model relates to the related technical field of power adapter, propose a kind of power circuit and power adapter for realizing surge and static electricity protection, by being arranged in the main chip control circuit and output end bidirectional transient voltage suppression diode, and discharge needle structure is arranged in PCB secondary output end, form multistage static clamp and preferential discharge path, can effectively guide and release high-voltage static electricity energy, avoid its into main circuit, simultaneously, also can realize surge protection, significantly improve the anti-static ability and overall electromagnetic compatibility performance of power system.

Description

Technical Field

[0001] This utility model relates to the field of power adapter technology, specifically to a power circuit and power adapter that provides surge and electrostatic protection. Background Technology

[0002] The statements in this section are merely background information related to this utility model and do not necessarily constitute prior art.

[0003] Power adapters, serving as a crucial bridge between electronic devices and the power grid, are widely used in network communication equipment such as network cameras, switches, and robotic vacuum cleaners, as well as smart home products. They are essential components for ensuring stable power supply and normal operation of systems. However, as electronic devices become increasingly integrated, miniaturized, and operate at lower voltages, their sensitivity to electrostatic discharge (ESD) interference has significantly increased. The output terminal of the power adapter, as a vital path directly connecting to external devices, has become one of the main channels through which electrostatic discharge enters electronic systems.

[0004] In complex electromagnetic environments or dry climates, ESD events are more frequent. Their sources include human contact, plugging and unplugging interfaces, and ground potential differences. They often exhibit transient high voltages exceeding 30kV, rapid rise times (nanosecond levels), and high energy densities, far exceeding the tolerance capabilities of typical electronic components. When electrostatic energy is conducted from the adapter's output or signal interface into the internal circuitry, it first affects core modules such as the pre-amplifier filter, rectifier bridge, DC-DC converter, PWM controller, and secondary MCU, causing multifaceted damage.

[0005] The inventors discovered in their research that current mainstream adapters primarily employ ESD protection methods based on discrete components such as varistors (MOVs) or gas discharge tubes (GDTs), with their maximum withstandable electrostatic shock typically set at 15kV according to the IEC 61000-4-2 standard. However, this protection level is significantly insufficient in practical applications, failing to withstand higher levels of electrostatic shock (such as 20kV or even 30kV), and exhibiting a relatively long response time, which is inadequate for suppressing rapid transient interference. Utility Model Content

[0006] To address the aforementioned problems, this invention proposes a power supply circuit and power adapter that provides surge and electrostatic protection. By incorporating bidirectional transient voltage suppression diodes in the main control circuit and at the output terminal, and a discharge pin structure on the secondary side of the PCB, a multi-stage electrostatic clamping and preferential discharge path is formed. This effectively guides and releases high-voltage electrostatic energy, preventing it from entering the main circuit. Simultaneously, it also provides surge protection, significantly improving the anti-static capability and overall electromagnetic compatibility performance of the power supply system.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] One or more embodiments provide a power supply circuit for surge and electrostatic discharge protection, including a main chip control circuit. The main chip control circuit adopts a PWM control circuit. The FB pin and VDD pin of the main controller chip U1 of the PWM control circuit are respectively connected to bidirectional TVS transistors to clamp the electrostatic energy entering the FB pin and VDD pin of the main controller chip U1.

[0009] One or more embodiments provide a power adapter that employs one of the power circuits described above for surge and electrostatic discharge protection.

[0010] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0011] This invention prevents high-voltage electrostatic signals or surge interference from entering the main controller chip U1 through its sensitive pins. Bidirectional TVS diodes ZD1 and ZD3 are connected in parallel to its FB and VDD pins, respectively. These diodes can quickly conduct when the electrostatic or surge voltage exceeds their breakdown voltage threshold, forming a low-impedance discharge path and guiding the overvoltage to ground, thus providing voltage clamping and protection for the chip. This arrangement constructs a front-end electrostatic barrier, effectively blocking the influence of external high-energy pulses on the function of the main controller chip U1.

[0012] The advantages and additional benefits of this utility model will be described in detail in the following specific embodiments. Attached Figure Description

[0013] The accompanying drawings, which form part of this specification, are used to provide a further understanding of this utility model. The illustrative embodiments of this utility model and their descriptions are used to explain this utility model and do not constitute a limitation thereof.

[0014] Figure 1 This is a power supply circuit diagram for implementing surge and electrostatic protection according to Embodiment 1 of this utility model;

[0015] Figure 2 This is a circuit diagram of the surge protection circuit of Embodiment 1 of this utility model;

[0016] Figure 3 This is a circuit diagram of the input rectifier and filter circuit of Embodiment 1 of this utility model;

[0017] Figure 4 This is a circuit diagram of the main chip control circuit of Embodiment 1 of this utility model;

[0018] Figure 5This is a circuit diagram of the absorption circuit and the output rectifier filter circuit of Embodiment 1 of this utility model;

[0019] Figure 6 This is a schematic diagram of the PCB board example manufactured according to Embodiment 1 of this utility model, showing the arrangement of discharge pins. Detailed Implementation

[0020] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0021] It should be noted that the following detailed description is exemplary and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0022] It should be noted that the terminology used herein is for descriptive purposes only and is not intended to limit the exemplary embodiments according to this invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof. It should be noted that, without conflict, the various embodiments and features within those embodiments can be combined with each other. The embodiments will now be described in detail with reference to the accompanying drawings.

[0023] In one or more of the technical solutions disclosed in the implementation methods, such as Figures 1 to 6 As shown, a power supply circuit for surge and electrostatic protection includes an AC input terminal for AC power supply, a surge protection circuit, an input rectifier and filter circuit, an absorption circuit, a main chip control circuit, a transformer, an output rectifier and filter circuit, and a secondary output terminal.

[0024] In some embodiments, the main chip control circuit adopts a PWM control circuit. The FB pin and VDD pin of the main controller chip U1 of the PWM control circuit are respectively connected to bidirectional TVS transistors to clamp the electrostatic energy entering the pin and prevent electrostatic voltage from damaging the PWM control chip.

[0025] In this embodiment, the bidirectional TVS diode refers to a bidirectional transient voltage suppressor diode, which is simply referred to as a bidirectional TVS diode. A bidirectional transient voltage suppressor diode is a voltage protector with bidirectional discharge capability. The working principle of a bidirectional TVS diode is based on the voltage limiting characteristics of a PN junction. When the circuit is operating normally, the voltage between the P and N terminals of the bidirectional TVS diode remains at a low threshold level and will not affect the circuit. When a high voltage occurs, the voltage between the P and N terminals of the bidirectional TVS diode will exceed the threshold level. At this time, the diode will conduct, discharging the excess voltage to ground. This protects the circuit from damage caused by high voltage.

[0026] Specifically, in this embodiment, bidirectional TVS transistor ZD1 is connected to the FB pin of the main controller chip U1, and bidirectional TVS transistor ZD3 is connected to the VDD pin of the main controller chip U1.

[0027] Optionally, the main controller chip U1 can be SP2637AHF; Figure 1 In this context, the ZD1 model of the bidirectional TVS diode can be SDO5C; the ZD2 model can be SD18C; and the ZD3 model can be SD18C or SD24C.

[0028] In this embodiment, the main chip control circuit is based on the PWM (Pulse Width Modulation) control principle to achieve precise adjustment and dynamic stability control of the power supply output voltage. The main controller chip U1 serves as the core PWM control chip, with its FB pin responsible for sampling the feedback voltage to adjust the output duty cycle; the VDD pin provides the chip's operating power supply voltage. To prevent high-voltage electrostatic signals or surge interference from entering the chip through these two sensitive pins, bidirectional TVS diodes ZD1 and ZD3 are connected in parallel to its FB and VDD pins, respectively. The bidirectional TVS diodes feature low clamping voltage and extremely fast response time, allowing them to quickly conduct when electrostatic or surge voltage exceeds their breakdown voltage threshold, forming a low-impedance discharge path to guide the overvoltage to ground, thus providing voltage clamping and protection for the chip. This arrangement constructs a front-stage electrostatic barrier, effectively blocking the influence of external high-energy pulses on the PWM chip's function.

[0029] This implementation significantly improves the anti-interference capability of the power control system by introducing bidirectional TVS diodes into the key pins (FB and VDD) of the main chip U1. Especially when facing abnormal events such as sudden electrostatic discharge and lightning surges, it can significantly reduce the failure rate and probability of malfunction of the control chip. This design not only ensures the stable operation of the PWM control loop but also indirectly improves the stability and reliability of the entire power circuit output.

[0030] In one possible implementation, a bidirectional TVS diode ZD2 is connected in parallel at the secondary output of the power supply circuit.

[0031] In this embodiment, a bidirectional TVS diode ZD2 is connected in parallel at the secondary output of the power supply circuit. Its main function is to provide a fast voltage clamping path when the output is subjected to electrostatic discharge (ESD) or lightning surge voltage interference. The bidirectional TVS diode has the ability to respond to bipolar transient voltages. When the output voltage exceeds its breakdown voltage VBR, ZD2 quickly switches from a high-impedance state to a low-impedance conduction state, dissipating the excess voltage energy through the ground wire. This prevents high voltage from entering subsequent load circuits or chip modules, thereby achieving dual protection against ESD and surge at the output. The clamping process has an extremely short response time, typically in the picosecond to nanosecond range, ensuring that the protection action is completed before the arrival of high-energy transient signals.

[0032] The above circuit structure can simultaneously achieve surge protection. The surge protection path is as follows: when a lightning surge enters the L / N line, the varistor MOV1 activates, clamping the voltage to below 1KV. The voltage is then coupled to the secondary winding and auxiliary winding via the transformer winding. The energy entering the auxiliary winding is further processed by bidirectional TVS diodes ZD1 and ZD3 to reduce the voltage and dissipate the energy. The energy entering the secondary winding is further processed by bidirectional TVS diode ZD2 to reduce the voltage and dissipate the energy, thereby achieving the function of surge protection.

[0033] In some embodiments, such as Figure 6 As shown, the secondary output terminal of the power supply circuit PCB is equipped with discharge pins, including a secondary-side discharge pin A1 and a primary-side discharge pin A2. The secondary-side discharge pin A1 is electrically connected to the solder joint of the negative terminal V- of the secondary output terminal. The distance between the secondary-side discharge pin A1 and the primary-side discharge pin A2 is less than a set distance, which is used to form an arc discharge when there is electrostatic voltage. The electrostatic energy is converted into heat energy through the arc discharge of the discharge pin, and the remaining small part is released back to the power grid, so as to prevent ESD energy from entering the main circuit of the power supply circuit and damaging the power supply.

[0034] The aforementioned power supply circuit structure is designed to enhance protection against electrostatic discharge (ESD) interference. Metal discharge pins are positioned near the secondary output terminal of the PCB board, forming an arc path when high-voltage electrostatic discharge is present. Under high-voltage impact, the electrostatic charge is released along this arc path, guided to the power grid via the discharge pins, thus bypassing the main power supply circuit and preventing damage to the chip and other sensitive components. The arc discharge path is connected to the AC pin ground terminal via metal traces or copper foil layers on the PCB board, achieving rapid dissipation of electrostatic energy. This path serves as the first line of defense against ESD within the power supply and is the front-end strategy of the ESD protection system.

[0035] When faced with high-voltage electrostatic discharge interference, traditional designs are prone to chip damage, system malfunctions, or insufficient anti-interference capabilities. In existing technologies, because the power output terminal is exposed to an external connector, it is easily a path for electrostatic intrusion. Existing solutions directly cut off the power supply through the operation of electrical components, resulting in a delayed response or insufficient clamping capability to strong electrostatic voltages directly introduced through the terminals.

[0036] This embodiment creates a physical channel for arc discharge under high electrostatic voltage by placing a discharge pin at the secondary output terminal of the power supply circuit PCB. This allows electrostatic energy to be preferentially released through the discharge pin, effectively preventing electrostatic discharge from entering the main circuit, thus achieving efficient and active electrostatic protection for the power supply circuit. This significantly enhances the power supply product's protection capability against electrostatic surges up to 30KV. The action does not rely on electrical actuators; the higher the voltage level, the faster the response speed, improving overall response time. This method avoids electrostatic energy directly entering the control chip and filter module, effectively extending circuit life and improving the overall system stability and reliability.

[0037] One feasible technical solution is that the discharge needle is configured as a conductive metal tip structure. Different materials can be used for the metal discharge needle. Preferably, the discharge needle is made of copper foil.

[0038] Figure 6 It is by Figure 1 The example PCB board fabrication of the circuit structure is mainly for marking the position of the discharge pins. The arrangement of electrical components on the PCB board is only an example and is not intended to limit the structure of the circuit board fabrication in this embodiment. It is understood that it can also be arranged according to other needs of those skilled in the art, and the position and orientation of each circuit component can be randomly adjusted as needed.

[0039] Figure 6 In the text, the corresponding positions marked V- and V+ are... Figure 1 The secondary output terminal is shown in red. The red dotted line represents the electrostatic discharge path formed by the path laid out on the PCB. The electrostatic charge enters through the secondary output terminal V- and forms a discharge path through the secondary side discharge pin A1 and the primary side discharge pin A2. The primary side discharge pin A2 is connected to the AC input terminal L through the path set on the PCB, thereby conducting the remaining electrostatic charge into the power grid. Figure 6 In the diagram, B represents a slot on the PCB board to meet the primary-secondary distance requirements of safety regulations.

[0040] In some embodiments, such as Figure 1 and Figure 2 As shown, the surge protection circuit is connected between terminals L and N of the power input terminal, including a thermistor NTC1 and a fuse F1 connected in series at the power input terminal, and a varistor MOV1 connected in parallel at the power input terminal.

[0041] The parallel connection of varistor MOV1 at the power input terminal forms a clamping path for high-voltage surges between L and N terminals. Under normal voltage conditions, MOV1 exhibits high resistance. When lightning strikes or grid anomalies cause the voltage to rise above its operating voltage, its impedance rapidly decreases, absorbing and dissipating surge energy to prevent high voltage from entering the main circuit. Thermistor NTC1 is connected between the L terminal and the main circuit input terminal to suppress large current inrushes at the moment of power-on, limiting the surge current amplitude. NTC1 is a negative temperature coefficient thermistor; its resistance is high initially to suppress inrush current, and gradually decreases as the temperature rises, having minimal impact on the circuit during normal operation. Fuse F1 acts as an overcurrent protection device, melting when the current abnormally increases (such as in a short circuit or component breakdown), cutting off the power supply and protecting downstream circuits from damage. This circuit as a whole provides effective dual protection against surge voltage and surge current, ensuring reliable operation of the power module even in harsh power supply environments.

[0042] In the above technical solution, a discharge pin and a bidirectional TVS diode ZD2 are provided at the output end of the power supply, and bidirectional TVS diodes ZD1 and ZD3 are provided on the pins of the controller chip. ， High-voltage electrostatic discharge (ESD) protection is achieved through a three-level protection system. In cases of high ESD energy, arcing can occur, converting electrical energy into heat. The bidirectional TVS diode is based on the avalanche breakdown principle of semiconductor PN junctions. Under normal voltage, the bidirectional TVS diode is in a high-resistivity state with only a small leakage current (nA level). When a transient voltage (such as an ESD pulse) exceeds its breakdown voltage (VBR), the bidirectional TVS diode transitions to a low-resistivity state within nanoseconds (10⁻¹² seconds), forming a discharge path that rapidly guides the current to ground while clamping the voltage at a safe level (typically 1.2–1.4 times VBR). Through proper selection of device parameters and margin design, and the coordinated design of multiple ESD protection levels, it is possible to ensure safe conduction and discharge of ESD energy even under higher levels of ESD shocks, such as 30kV, thereby protecting the circuit from damage.

[0043] In some embodiments, such as Figure 3 As shown, the input rectifier filter circuit includes a bridge rectifier BD1 connected in sequence, and a π-type filter circuit composed of capacitor EC1, inductor LF1 and capacitor EC2; the AC input terminal of the bridge rectifier BD1 is connected to the output of the surge protection circuit, and the output terminal is connected to the input terminal of the π-type filter circuit.

[0044] In the circuit described above, the bridge rectifier BD1 in the input rectifier filter circuit converts the input AC voltage into DC voltage. This DC voltage then enters a π-type filter network composed of capacitor EC1, inductor LF1, and capacitor EC2 to further remove high-frequency noise and low-frequency ripple. Specifically, capacitor EC1 is located on the input side of the π-type structure and is used to first filter out high-frequency interference signals contained in the AC rectification; inductor LF1 is connected between capacitors EC1 and EC2 to suppress rapid current changes and reduce low-frequency ripple; capacitor EC2, as a parallel capacitor at the output, acts as a buffer and energy storage capacitor, providing instantaneous current during load fluctuations to maintain the stability of the voltage output. The entire filtering system effectively improves the purity of the rectified DC voltage, providing a stable and reliable DC operating voltage for subsequent circuits.

[0045] The input rectifier filter circuit has a reasonable circuit structure design, which can effectively filter out interference components in different frequency bands at the same time, and also take into account the energy buffer function, significantly improving the quality of rectified output and ensuring the working efficiency and electrical stability of subsequent power conversion modules.

[0046] In some embodiments, such as Figure 4 As shown, the main chip control circuit includes a power supply circuit, a feedback circuit, and a current limiting protection circuit;

[0047] The power supply circuit includes a resistor R5, a diode D2, and a resistor R7A connected in series; a capacitor C2 and a resistor R11 are connected in parallel across the two ends of the diode D2; one end of the resistor R7A is connected to the VDD pin of the main controller chip U1; one end of the connection point of the diode D2 and the resistor R7A is grounded through the capacitor EC3, and the other end is connected to the output of the rectifier and filter circuit through the resistors R1 and R2.

[0048] The feedback circuit includes resistors R6 and R8 connected in series, with capacitor C3 connected in parallel across resistor R8; one end of resistor R6 is connected to the feedback sampling signal input node (output nodes 4 and 5 of transformer secondary winding T1B), and the connection point of resistors R6 and R8 is connected to the FB pin of the main control chip U1.

[0049] The feedback circuit is connected to the FB pin of the main controller chip U1 to achieve sampling feedback regulation of the output voltage. Capacitor C3 is connected in parallel across resistor R8 to filter out high-frequency interference components in the feedback signal and improve the stability of feedback control. In addition, a bidirectional TVS diode ZD1 is also connected in parallel across resistor R8 to clamp the FB pin when high-voltage transient interference occurs, preventing electrostatic discharge or surge voltage from entering the FB pin and causing damage to the control chip.

[0050] The current limiting protection circuit includes resistors R9 and R10 connected in parallel. One end of the parallel circuit is connected to the CS pin of the main controller chip U1, and the other end is grounded. When the current value exceeds the preset threshold, the PWM controller responds through the CS pin, triggering the overcurrent protection logic to quickly reduce or shut down the output power, thereby ensuring the safe operation of the subsequent circuits and power devices.

[0051] In some embodiments, such as Figure 5 As shown, the absorption circuit includes a primary absorption circuit and a secondary absorption circuit.

[0052] The primary absorption circuit is connected across the primary winding of transformer T1A and consists of an RCD absorption circuit composed of resistors R3 and R4, capacitors C1 and C1A, and diode D1. Resistors R3 and R4 are connected in series, and capacitors C1 and C1A are connected in parallel across resistor R4. Resistor R3 is connected to one end of the primary winding through diode D1, and resistor R4 is connected to the other end of the primary winding. This RCD absorption circuit is used to absorb the spike high voltage generated by the momentary disconnection of the switch in transformer T1A, preventing the high voltage from reverse-biasedly damaging the switching transistor.

[0053] The secondary absorption circuit is connected to the rectifier circuit on the secondary side of the transformer. It includes a resistor R12 and a capacitor C4 connected in series to form an RC absorption branch, which is used to absorb the spike energy caused by the secondary winding, reduce the output voltage spike, and protect the rectifier and filter components at the output.

[0054] The absorption circuit, through the combination of primary RCD absorption and secondary RC absorption, can dissipate the energy stored in the transformer leakage inductance, effectively suppress the energy backflow caused by the transformer leakage inductance, improve the electromagnetic interference characteristics of the system, enhance the system stability and reliability, and avoid high voltage damage to switching devices and output rectifier components.

[0055] In some embodiments, such as Figure 5 As shown, the output rectifier circuit is located at the output terminal of the secondary winding of transformer T1A, and is used to rectify and filter the output voltage.

[0056] The output rectifier circuit includes a rectifier diode D3, a capacitor EC4, and a current-limiting resistor R13. The anode of the rectifier diode D3 is connected to the transformer output terminal, and the cathode is connected to the output positive terminal V+ via the capacitor EC4. The capacitor EC4 and the current-limiting resistor R13 are connected in parallel across the secondary output terminal.

[0057] The output rectifier circuit also includes a bidirectional TVS diode ZD2 connected in parallel at its output terminal. Capacitor EC4 and diode D3 form a rectifier-filter branch to filter pulsating DC current and obtain a stable output voltage. The bidirectional TVS diode ZD2 is connected in parallel between the positive and negative terminals V+ and V- at the output terminal, and in parallel with a current-limiting resistor R13, to clamp high-energy electrostatic interference or sudden surge voltages, preventing abnormally high voltage from damaging the output circuit.

[0058] This output rectifier circuit not only performs output voltage rectification and filtering, but also has ESD suppression function at the output end. It is particularly suitable for combating common spike and surge interference in industrial environments, and improving the overall electromagnetic compatibility and anti-interference capability of the power module.

[0059] In the accompanying drawings of this embodiment, "option" indicates that the component or circuit part is an optional component or functional module, which can be flexibly added, removed or replaced according to actual needs.

[0060] The power supply circuit described in this embodiment improves the electrostatic discharge and surge protection level of electronic equipment, effectively reducing the failure rate caused by electrostatic discharge and surge impact. It has a fast response speed, capable of absorbing and dispersing electrostatic discharge and surge impact energy in a short time. Furthermore, it features output overvoltage protection, overcurrent protection, overload protection, VDD overvoltage protection, VDD undervoltage protection, and overtemperature protection. This effectively prevents damage to user equipment under abnormal conditions.

[0061] Example 2

[0062] Based on Embodiment 1, this embodiment provides a power adapter, which adopts a power circuit for surge and electrostatic protection as described in Embodiment 1;

[0063] The adapter includes an adapter housing and a circuit board disposed inside the adapter. The circuit board adopts a power supply circuit for surge and electrostatic protection as described in Embodiment 1.

[0064] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

[0065] Although the specific embodiments of the present utility model have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present utility model. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solution of the present utility model are still within the scope of protection of the present utility model.

Claims

1. A power supply circuit for surge and electrostatic discharge protection, characterized in that: It includes a main chip control circuit, which adopts a PWM control circuit. The FB pin and VDD pin of the main controller chip U1 of the PWM control circuit are respectively connected to bidirectional TVS transistors to clamp the electrostatic energy entering the FB pin and VDD pin of the main controller chip U1.

2. The power supply circuit for surge and electrostatic protection as described in claim 1, characterized in that: The power supply circuit includes, in sequence, an AC input terminal, a surge protection circuit, an input rectifier and filter circuit, an absorption circuit, a main chip control circuit, a transformer, an output rectifier and filter circuit, and a secondary output terminal; A bidirectional TVS diode ZD2 is connected in parallel at the secondary output terminal.

3. The power supply circuit for surge and electrostatic protection as described in claim 1, characterized in that: The secondary output terminal of the power supply circuit PCB is equipped with a discharge pin, which includes a secondary-side discharge pin A1 and a primary-side discharge pin A2. The secondary-side discharge pin A1 is electrically connected to the solder joint of the negative terminal V- of the secondary output terminal. The distance between the secondary-side discharge pin A1 and the primary-side discharge pin A2 is less than a set distance, which is used to form an arc discharge when there is electrostatic voltage.

4. A power supply circuit for surge and electrostatic discharge protection as described in claim 3, characterized in that: The discharge needle is a conductive metal tip structure, and the discharge needle is made of copper foil.

5. A power supply circuit for surge and electrostatic discharge protection as described in claim 2, characterized in that: The surge protection circuit is connected between terminals L and N of the power input terminal, including a thermistor NTC1 and a fuse F1 connected in series at the power input terminal, and a varistor MOV1 connected in parallel at the power input terminal.

6. A power supply circuit for surge and electrostatic discharge protection as described in claim 2, characterized in that: The input rectifier and filter circuit includes a bridge rectifier BD1 connected in sequence, and a π-type filter circuit composed of capacitor EC1, inductor LF1 and capacitor EC2; the AC input terminal of the bridge rectifier BD1 is connected to the output of the surge protection circuit, and the output terminal is connected to the input terminal of the π-type filter circuit. Alternatively, the absorption circuit may include a primary absorption circuit and a secondary absorption circuit; The primary absorption circuit is connected across the primary winding of transformer T1A and includes an RCD absorption circuit consisting of resistor R3, resistor R4, capacitor C1, capacitor C1A and diode D1. Resistor R3 and resistor R4 are connected in series, and capacitors C1 and C1A are connected in parallel across resistor R4. Resistor R3 is connected to one end of the primary winding through diode D1, and resistor R4 is connected to the other end of the primary winding. The secondary absorption circuit is connected to the rectifier circuit on the secondary side of the transformer, including a resistor R12 and a capacitor C4 connected in series to form an RC absorption branch.

7. A power supply circuit for surge and electrostatic discharge protection as described in claim 1, characterized in that: The main chip control circuit includes a power supply circuit, a feedback circuit, and a current limiting protection circuit.

8. A power supply circuit for surge and electrostatic discharge protection as described in claim 7, characterized in that: The power supply circuit includes a resistor R5, a diode D2, and a resistor R7A connected in series; a capacitor C2 and a resistor R11 are connected in parallel across the two ends of the diode D2; one end of the resistor R7A is connected to the VDD pin of the main controller chip U1; the connection point of the diode D2 and the resistor R7A is grounded through the capacitor EC3, and connected to the output of the rectifier and filter circuit through the resistors R1 and R2.

9. A power supply circuit for surge and electrostatic protection as described in claim 7, characterized in that: The feedback circuit includes resistors R6 and R8 connected in series, with capacitor C3 connected in parallel across resistor R8; one end of resistor R6 is connected to the feedback sampling signal input node, and the connection point between resistors R6 and R8 is connected to the FB pin of the main control chip U1. The current limiting protection circuit includes resistors R9 and R10 connected in parallel. One end of the parallel circuit is connected to the CS pin of the main controller chip U1, and the other end is grounded.

10. A power adapter, characterized in that: The power adapter employs a power circuit for surge and electrostatic protection as described in any one of claims 1-9.

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