Protection circuit and electronic device

Abstract

The application relates to the technical field of power electronics, and discloses a protection circuit and electronic equipment, wherein the protection circuit comprises a first branch circuit and a second branch circuit, the first branch circuit and the second branch circuit are connected and have a first node, and the first node is adapted to receive a power supply signal. The first branch circuit is configured to transmit the power supply signal to a power consumption device, and the second branch circuit is configured to provide a discharge path for a high-voltage transient pulse in the case that the high-voltage transient pulse exists. The application provides a discharge and clamping path with a simple circuit structure under the impact of a high-voltage transient pulse, ensures the anti-reverse connection and transient voltage protection effect, significantly reduces the production material cost, and thus meets the economic demand of mass production.

Description

Technical Field

[0001] This application relates to the field of power electronics technology, and in particular to a protection circuit and electronic device. Background Technology

[0002] In the port design of electronic devices, on the one hand, the power supply may be connected to the wrong polarity, and on the other hand, the port is prone to external transient high voltage pulses such as electrostatic discharge (ESD) and inductive load switching surges, which can damage the downstream circuits. Therefore, reverse connection protection and transient voltage suppression are the two basic requirements of port design.

[0003] In related technologies, diodes with very high withstand voltage are generally selected, such as high-voltage Schottky diodes or metal-oxide-semiconductor field-effect transistors (MOSFETs) specifically designed for reverse polarity protection. However, this circuit protection solution is very expensive, making it difficult to control material costs to meet requirements in mass production. Utility Model Content

[0004] This application provides a protection circuit and electronic device that solves the technical problem that the related technology is very expensive and difficult to meet the cost requirements of mass production. By using low-cost components to form the first and second branches, a simple circuit structure is provided to provide a discharge and clamping path under the impact of high voltage transient pulses. While ensuring the protection effect against reverse connection and transient voltage, the production material cost is significantly reduced, thereby meeting the economic requirements of mass production.

[0005] To achieve the above objectives, the main technical solutions adopted in this application include:

[0006] In a first aspect, embodiments of this application provide a protection circuit, the protection circuit including a first branch and a second branch, wherein the first branch and the second branch are connected and have a first node, the first node being adapted to receive a power signal;

[0007] The first branch is configured to transmit the power signal to the electrical equipment, and the second branch is configured to provide a discharge path for the high-voltage transient pulse in the event that the power signal is subject to a high-voltage transient pulse.

[0008] The protection circuit proposed in this application transmits the power signal to the electrical equipment through a first branch to achieve reverse connection protection, while a second branch provides a discharge path to prevent damage to the downstream circuitry when external high-voltage transient pulses are introduced into the power signal. Compared with related technologies, this application embodiment, through the synergistic effect of the first and second branches, can achieve reverse connection protection and high-voltage transient pulse protection for port circuits with a simple structure, and reduces the complexity and cost of circuit design. For large-scale production, it can significantly reduce material costs and manufacturing process difficulty.

[0009] Optionally, in some embodiments of this application, the first branch includes a first diode, the anode of the first diode being connected to the first node, and the cathode of the first diode being connected to the electrical device.

[0010] In this embodiment, a first diode is provided in the first branch so that, under normal operating conditions, the first diode utilizes its unidirectional conductivity to allow current to flow from the anode to the cathode, thereby transmitting the power signal to the electrical equipment, while effectively blocking reverse current, thus achieving a reliable reverse connection protection function.

[0011] Optionally, in some embodiments of this application, the first diode is a body diode inside a semiconductor device.

[0012] The embodiments of this application utilize the body diode inside the semiconductor device, which can effectively reduce the number of components on the printed circuit board (PCB), making the circuit layout more compact, greatly saving PCB space, and facilitating product miniaturization design.

[0013] Optionally, in some embodiments of this application, the second branch includes a first capacitor, a first end of which is connected to the first node, and a second end of which is connected to a reference ground.

[0014] This embodiment utilizes the characteristic that the capacitive reactance of a capacitor is inversely proportional to the frequency. When a high-voltage transient pulse exists in the power signal, the first capacitor has extremely low impedance, forming a low-impedance path and providing a discharge path for the high-voltage transient pulse. In this way, most of the high-frequency pulse current can be directly shunted to ground using only a single, inexpensive capacitor, avoiding damage to the first diode and the subsequent circuitry, and significantly reducing the cost of circuit components.

[0015] Optionally, in some embodiments of this application, the capacitance value of the first capacitor is from 470pF to 2200pF.

[0016] With the capacitance value of the first capacitor between 470pF and 2200pF, the first capacitor can effectively cover 8kV of ESD protection, providing a sufficiently low impedance path to achieve effective current shunting. This allows the entire protection circuit to have high-efficiency protection performance while also having good stability and compatibility, achieving reliable protection for the back-end circuits at low cost.

[0017] Optionally, in some embodiments of this application, the first capacitor is any one of a ceramic capacitor, a film capacitor, and a silicon capacitor.

[0018] Optionally, in some embodiments of this application, the protection circuit further includes a third branch connected in parallel across the two ends of the first branch to clamp the voltage across the two ends of the first branch.

[0019] By setting up a third branch connected in parallel with both ends of the first branch, when a high-voltage transient pulse appears in the circuit, the third branch can quickly clamp the voltage at both ends of the first branch. On the one hand, it provides a shunt path for the high-voltage transient pulse, and on the other hand, it prevents the components in the first branch from being damaged by excessive voltage at both ends, ensuring the stability of the reverse connection protection function of the first branch and further enhancing the reliability of the entire protection circuit.

[0020] Optionally, in some embodiments of this application, the third branch includes a second capacitor, the first end of which is connected to the first node, and the second end of which is connected to the electrical equipment.

[0021] When a high-voltage transient pulse appears in the circuit, based on the characteristic that the capacitive reactance is inversely proportional to the frequency, the second capacitor provides a low-impedance parallel path for the first branch, making it difficult for the high-voltage transient pulse to form a high voltage difference across the first branch, thereby protecting the components in the first branch from reverse breakdown.

[0022] Optionally, in some embodiments of this application, the protection circuit further includes a third branch, a first end of which is connected to the first branch and has a second node, a second end of which is connected to a reference ground, and the first branch is configured to transmit the power signal to the electrical device through the second node.

[0023] The embodiments of this application utilize the first branch, the second branch, and the third branch to form a π-type filter circuit, thereby effectively preventing damage to the downstream circuit from high-voltage transient pulses in the power supply signal.

[0024] Secondly, embodiments of this application provide an electronic device, which includes the protection circuit described in the above embodiments. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the port protection circuit in related technologies;

[0027] Figure 2 This is a schematic diagram of the structure of the protection circuit proposed in this application in one embodiment;

[0028] Figure 3 This is a schematic diagram of the structure of the protection circuit proposed in another embodiment of this application;

[0029] Figure 4 This is a schematic diagram of the protective circuit proposed in yet another embodiment. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0031] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the description of this application is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms "comprising" and "having," and any variations thereof, in the description, claims, and accompanying drawings of this application are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the description, claims, or accompanying drawings of this application are used to distinguish different objects, not to describe a specific order or hierarchy.

[0032] In this application, the reference to "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this application can be combined with other embodiments.

[0033] To achieve port protection, the unidirectional conductivity of diodes is typically used to provide reverse connection protection. However, because ordinary diodes, which are low-cost and have low voltage withstand capabilities, are easily damaged by high-voltage transient pulses, some related technologies directly use dedicated reverse connection protection devices such as Schottky diodes or transient voltage suppressor (TVS) diodes. However, this circuit protection solution is very expensive, making it difficult to control material costs to meet cost requirements in mass production.

[0034] In other related technologies, such as Figure 1 As shown, a common, low-cost reverse polarity protection diode D is used. N Its anode is connected to the power signal VIN, its cathode is connected to the back-end circuit, and a TVS diode D is connected between its anode and ground. T When a high-voltage transient pulse occurs, a TVS diode quickly limits the voltage to a safe range, thus protecting the reverse connection protection diode and downstream circuitry. However, TVS diodes that meet the high-voltage transient pulse protection requirements are still very expensive and increase PCB footprint.

[0035] Therefore, there is an urgent need for a protection circuit that can effectively overcome the shortcomings of low-cost devices that are prone to damage due to insufficient voltage withstand, while avoiding the use of high-cost devices.

[0036] To address the aforementioned problems, this application provides a protection circuit 10, such as... Figure 2 As shown, the protection circuit 10 can be used in port circuit designs such as power input ports, USB interfaces, and communication interfaces. The protection circuit 10 includes a first branch 11 and a second branch 12, wherein the first branch 11 and the second branch 12 are connected and have a first node, which is adapted to receive the power signal VIN.

[0037] The first branch 11 is configured to transmit the power signal VIN to the electrical equipment 20, and the second branch 12 is configured to provide a discharge path for the high voltage transient pulse in the event of a high voltage transient pulse in the power signal VIN.

[0038] Specifically, the first branch 11 has unidirectional conductivity, with one end connected to the power supply equipment and the other end connected to the electrical equipment 20. It achieves reverse connection protection by blocking reverse current, ensuring the normal operation of the electrical equipment 20. The second branch 12 is used to deal with high-voltage transient pulses that may appear in the power signal VIN. When high-voltage transient pulses occur, the second branch 12 can provide a low-impedance discharge path for these pulses, allowing them to flow directly to ground.

[0039] The protection circuit 10 provided in this embodiment transmits the power signal VIN to the electrical device 20 through a first branch 11 to achieve reverse connection protection. Simultaneously, a second branch 12 provides a discharge path to prevent damage to downstream circuits caused by external high-voltage transient pulses introduced into the power signal VIN. Compared with related technologies, this embodiment, through the synergistic effect of the first branch 11 and the second branch 12, can achieve reverse connection protection and high-voltage transient pulse protection for port circuits with a simple structure, reducing the complexity and cost of circuit design. For large-scale production, this can significantly reduce material costs and manufacturing process difficulty.

[0040] like Figure 2 As shown, in some embodiments of this application, the first branch 11 includes a first diode D1, the anode of the first diode D1 is connected to the first node, and the cathode of the first diode D1 is connected to the electrical device 20.

[0041] Specifically, this embodiment uses a common diode, such as a rectifier diode of model 1N4007. This type of diode has a relatively low reverse withstand voltage but low cost, making it suitable for mass production with cost-effectiveness requirements. When the power signal VIN is positive, the first diode D1 conducts, allowing the power signal VIN to be transmitted to the electrical equipment 20, ensuring its normal operation. When a reverse connection occurs, the first diode D1 is cut off, effectively preventing reverse current from flowing, thus achieving reliable reverse connection protection and avoiding irreversible damage to the electrical equipment 20 caused by reverse current.

[0042] In this embodiment of the application, a first diode D1 is provided in the first branch 11, so that under normal working conditions, the first diode D1 uses its unidirectional conductivity to allow current to flow from the anode to the cathode, thereby transmitting the power signal VIN to the electrical equipment 20, while effectively blocking reverse current, thus realizing a reliable reverse connection protection function.

[0043] Furthermore, in some embodiments of this application, the first diode D1 may also be a body diode inside a semiconductor device, such as the body diode inside a semiconductor transistor like a MOSFET.

[0044] Thus, with Figure 2 Compared to the embodiments shown, the embodiments of this application utilize the body diode inside the semiconductor device, which can effectively reduce the number of components on the PCB, making the circuit layout more compact, greatly saving PCB space, and facilitating product miniaturization design.

[0045] like Figure 2 As shown, in some embodiments of this application, the second branch 12 includes a first capacitor C1, the first end of the first capacitor C1 is connected to the first node, and the second end of the first capacitor C1 is connected to the reference ground GND.

[0046] Specifically, the impedance formula for a capacitor is shown in the following formula (1):

[0047]

[0048] In the formula, Z C Let f be the impedance of the capacitor, f be the frequency, and C be the capacitance value.

[0049] When a high-voltage transient pulse exists in the power signal VIN, based on the characteristic that the capacitive reactance is inversely proportional to the frequency, under the high-frequency action of the high-voltage transient pulse, the first capacitor C1 exhibits extremely low impedance, so that most of the pulse current will be directly shunted to ground through this low-impedance path, without impacting the first diode D1 and the back-end circuit of the electrical equipment 20.

[0050] This embodiment utilizes the characteristic that the capacitive reactance of a capacitor is inversely proportional to the frequency. When a high-voltage transient pulse exists in the power signal VIN, the first capacitor C1 has extremely low impedance, forming a low-impedance path and providing a discharge path for the high-voltage transient pulse. In this way, most of the high-frequency pulse current can be directly shunted to ground using only a single, inexpensive capacitor, avoiding damage to the first diode D1 and the subsequent circuitry, and significantly reducing the cost of circuit components.

[0051] Furthermore, in some embodiments of this application, the capacitance value of the first capacitor C1 is 470pF to 2200pF.

[0052] Preferably, the capacitance of the first capacitor C1 is 1000pF, so that the first capacitor C1 can present a sufficiently low impedance at high frequencies to achieve effective current shunting, while not having too much impact on the normally operating circuit.

[0053] With the capacitance value of the first capacitor C1 between 470pF and 2200pF, the first capacitor C1 can effectively cover the 8kV ESD protection required by IEC 61000-4-2, providing a sufficiently low impedance path to achieve effective current shunting. Thus, the entire protection circuit 10 has good stability and compatibility while possessing high-efficiency protection performance, achieving reliable protection of the back-end circuit of the electrical equipment 20 at low cost.

[0054] Furthermore, in some examples of embodiments of this application, the capacitance value of the first capacitor C1 can also be 220pF, which is better suited for high-frequency electrical equipment 20. In other examples of embodiments of this application, the capacitance value of the first capacitor C1 can also be 4700pF, so as to more effectively absorb and buffer surge energy and provide reliable protection for the circuit in high surge environments.

[0055] In some embodiments of this application, the first capacitor C1 is any one of a ceramic capacitor, a film capacitor, and a silicon capacitor.

[0056] Specifically, the device cost of ceramic capacitors, film capacitors, and silicon capacitors is far lower than that of TVS diodes, thus significantly reducing the production cost of protection circuits. Preferably, in some examples of embodiments of this application, multilayer ceramic capacitors (MLCCs) in 0402 or 0603 packages can be used, which occupy less PCB area than TVS diodes with the same protection level, thereby facilitating miniaturization of product design.

[0057] Figure 3 The circuit structure of the protection circuit 10 in some other embodiments of this application is shown, such as Figure 3 As shown, the protection circuit 10 also includes a third branch 13, which is connected in parallel across the two ends of the first branch 11 to clamp the voltage across the two ends of the first branch 11.

[0058] Specifically, the third branch 13 serves as a supplementary discharge path to the first branch 11, providing a low-impedance parallel path for the high-frequency voltage across the first diode D1. This makes it difficult for high-voltage transient pulses to establish a high voltage difference across the first diode D1, thereby protecting the first diode D1 from reverse breakdown.

[0059] By setting a third branch 13 connected in parallel with the two ends of the first branch 11, when a high-voltage transient pulse appears in the circuit, the third branch 13 can quickly clamp the voltage at both ends of the first branch 11. On the one hand, it provides a shunt path for the high-voltage transient pulse, and on the other hand, it ensures that the components in the first branch 11 will not be damaged due to excessive voltage at both ends, thus ensuring the stability of the reverse connection protection function of the first branch 11 and further enhancing the reliability of the entire protection circuit 10.

[0060] In some other embodiments of this application, the third branch 13 includes a second capacitor C2, the first end of which is connected to the first node, and the second end of which is connected to the electrical equipment 20.

[0061] Specifically, when a high-voltage transient pulse exists in the power signal VIN, based on the characteristic that capacitive reactance is inversely proportional to frequency, the second capacitor C2 exhibits extremely low impedance under the high-frequency action of the high-voltage transient pulse. According to the characteristic that the voltages of parallel components are equal, the second capacitor C2 can effectively clamp the voltage across the first diode D1, making it difficult for it to rise to the breakdown value. The capacitance value of the second capacitor C2 is determined based on parasitic inductance generated by the traces in the printed circuit board assembly (PCBA), and preferably, the capacitance value of the second capacitor C2 is 100nF.

[0062] When a high voltage transient pulse occurs in the circuit, the second capacitor C2 is used to make it difficult for the high voltage transient pulse to form a high voltage difference across the first branch 11, thereby protecting the components in the first branch 11 from reverse breakdown.

[0063] In some other embodiments of this application, such as Figure 4 As shown, the first end of the third branch 13 is connected to the first branch 11 and has a second node, the second end of the third branch 13 is connected to the reference ground GND, and the first branch 11 is configured to transmit the power signal VIN to the electrical device 20 through the second node.

[0064] Specifically, one end of the first capacitor C1 in the second branch 12 is connected to the anode of the first diode D1 in the first branch 11, and the other end of the first capacitor C1 is connected to the reference ground GND. One end of the second capacitor C2 in the third branch 13 is connected to the cathode of the first diode D1, and the other end of the second capacitor C2 in the third branch 13 is connected to the reference ground GND. Therefore, the first capacitor C1, the first diode D1, and the second capacitor C2 form a π-type filter circuit, thereby allowing the high-frequency components of the power signal VIN to flow to ground through a low-impedance path.

[0065] In this embodiment, the first branch 11, the second branch 12 and the third branch 13 are used to form a π-type filter circuit, thereby effectively avoiding damage to the downstream circuit by the high voltage transient pulse in the power signal VIN.

[0066] Furthermore, in some embodiments of this application, the first branch 11 may include a first capacitor C1 and a third capacitor C3 connected between the anode of the first diode D1 and the reference ground GND, and the first capacitor C1 and the third capacitor C3 are connected in parallel to realize the expansion of the capacitor network. The specific circuit principle can be referred to the foregoing embodiments, and will not be repeated here.

[0067] Accordingly, this application also provides an electronic device, which includes the protection circuit 10 as described in the above embodiments. The specific configuration of the protection circuit 10 is described in the above embodiments and will not be repeated here.

[0068] The electronic device proposed in this embodiment can achieve reverse connection protection and high voltage transient pulse protection for port circuits with a simple structure through the protection circuit 10, and reduces the complexity and cost of circuit design. For large-scale production, it can significantly reduce material costs and production process difficulty.

[0069] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0070] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0071] The above description is merely an embodiment of this application and is not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

[0072] Although embodiments of this application have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of this application, and all such modifications and variations fall within the scope defined by the appended claims.

Claims

1. A protection circuit, characterized in that, The protection circuit includes a first branch (11) and a second branch (12), wherein the first branch (11) and the second branch (12) are connected and have a first node, the first node being adapted to receive a power signal; The first branch (11) is configured to transmit the power signal to the electrical equipment (20), and the second branch (12) is configured to provide a discharge path for the high voltage transient pulse in the event that the power signal is subject to a high voltage transient pulse.

2. The protection circuit according to claim 1, characterized in that, The first branch (11) includes a first diode D1, the anode of the first diode D1 is connected to the first node, and the cathode of the first diode D1 is connected to the electrical equipment (20).

3. The protection circuit according to claim 2, characterized in that, The first diode D1 is a body diode inside the semiconductor device.

4. The protection circuit according to claim 1, characterized in that, The second branch (12) includes a first capacitor C1, the first end of which is connected to the first node, and the second end of which is connected to the reference ground.

5. The protection circuit according to claim 4, characterized in that, The capacitance of the first capacitor C1 is between 470pF and 2200pF.

6. The protection circuit according to claim 4 or 5, characterized in that, The first capacitor C1 is any one of a ceramic capacitor, a film capacitor, and a silicon capacitor.

7. The protection circuit according to claim 1, characterized in that, The protection circuit also includes a third branch (13), which is connected in parallel to the two ends of the first branch (11) to clamp the voltage at both ends of the first branch (11).

8. The protection circuit according to claim 7, characterized in that, The third branch (13) includes a second capacitor C2, the first end of which is connected to the first node, and the second end of which is connected to the electrical equipment (20).

9. The protection circuit according to claim 1, characterized in that, The protection circuit further includes a third branch (13), the first end of which is connected to the first branch (11) and has a second node, the second end of which is connected to a reference ground, and the first branch (11) is configured to transmit the power signal to the electrical device (20) through the second node.

10. An electronic device, characterized in that, The electronic device includes the protection circuit as described in any one of claims 1 to 9.

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