Electromagnetic shielding protection circuit and device

Abstract

The invention provides an electromagnetic shielding protection circuit and device. The circuit comprises an input end, an output end, a grounding end, an anti-reverse connection circuit, a first protection circuit, a second protection circuit and a filter circuit. The anti-reverse-connection circuit is connected with the input end and the grounding end and is configured to receive the input power supply of the input end by using an MOS transistor in the circuit, and the circuit is disconnected when the input power supply is reversely connected; the first protection circuit is connected with the reverse connection prevention circuit and the grounding end and is configured to carry out voltage impact exceeding a first threshold value on the input power supply; the second protection circuit is connected with the first protection circuit and the grounding end and is configured to carry out current impact exceeding a second threshold value on the input power supply; and the filter circuit is connected with the second protection circuit, the grounding end and the output end, and is configured to filter differential-mode interference and common-mode interference of the input power supply, generate an output power supply and output the output power supply through the output end.

Description

Technical Field

[0001] The present application relates to the field of circuit protection technology, and in particular to an electromagnetic shielding protection circuit and device. Background Art

[0002] The power interface is connected to the power grid through a power cord to provide electrical energy for electrical equipment. The product generates various interferences during operation, such as interferences generated by power conversion circuits, high-frequency transformers, digital circuits, etc. These interferences form conducted interference to the power grid and radiated interference to space through the power interface; when a high-power inductive load is switched on or off on the power grid or the power grid is struck by lightning, transient pulse interference and surge interference will be generated at the power interface. If the power interface is not designed with protective filtering, these interferences will easily affect the normal operation of the product. Lightning interference can even damage the equipment. Therefore, the power interface needs to be designed for electromagnetic compatibility to ensure stable operation of the equipment. Summary of the invention

[0003] In view of this, the present application proposes an electromagnetic shielding protection circuit and device to solve or partially solve the above problems.

[0004] Based on the above purpose, the present application provides an electromagnetic shielding protection circuit, including: an input end, an output end, a ground end, an anti-reverse connection circuit, a first protection circuit, a second protection circuit and a filter circuit;

[0005] The anti-reverse connection circuit is connected to the input terminal and the ground terminal, and is configured to receive the input power of the input terminal by using the MOS transistor in the circuit, and disconnect when the input power is reversely connected;

[0006] The first protection circuit is connected to the anti-reverse connection circuit and the ground terminal, and is configured to perform a voltage shock exceeding a first threshold on the input power supply;

[0007] The second protection circuit is connected to the first protection circuit and the ground terminal, and is configured to impact the input power supply with a current exceeding a second threshold;

[0008] The filter circuit is connected to the second protection circuit, the ground terminal and the output terminal, and is configured to filter out differential mode interference and common mode interference of the input power supply, and generate output power to be output through the output terminal.

[0009] In some exemplary embodiments, the reverse connection prevention circuit includes: a MOS transistor, a first resistor, a second resistor, a third resistor, a first capacitor, a second capacitor, and a first transient voltage suppression diode;

[0010] The MOS transistor has a first electrode connected to the input terminal, a second electrode connected to the first protection circuit, and a control electrode connected to the ground terminal via a third resistor;

[0011] The first resistor has a first end connected to the first electrode of the MOS transistor and a second end connected to the first capacitor;

[0012] The first capacitor has a first end connected to the first resistor and a second end connected to the second electrode of the MOS transistor;

[0013] The second resistor has a first end connected to the second electrode of the MOS transistor and a second end connected to the control electrode of the MOS transistor;

[0014] The first transient voltage suppression diode has a first end connected to the second electrode of the MOS transistor and a second end connected to the control electrode of the MOS transistor;

[0015] The second capacitor has a first end connected to the second electrode of the MOS transistor, and a second end connected to the control electrode of the MOS transistor.

[0016] In some exemplary embodiments, the circuit further comprises: a power ground terminal; the first protection circuit comprises: a first varistor, a second varistor, a third varistor and a gas discharge tube;

[0017] The first varistor has a first end connected to the anti-reverse connection circuit and the second protection circuit, and a second end connected to the ground end;

[0018] The second varistor has a first end connected to the anti-reverse connection circuit and the second protection circuit, and a second end connected to the third varistor and the gas discharge tube;

[0019] The third varistor has a first end connected to the second varistor and a second end connected to the ground end;

[0020] The gas discharge tube has a first end connected to the second varistor and a second end connected to the power ground.

[0021] In some exemplary embodiments, the second protection circuit includes: a resettable fuse, at least one second transient voltage suppression diode, and at least one third capacitor;

[0022] The resettable fuse has a first end connected to the first protection circuit and a second end connected to the filter circuit;

[0023] The at least one second transient voltage suppression diode has a first end connected to the second end of the resettable fuse and a second end connected to the ground end;

[0024] The at least one third capacitor has a first end connected to the first end of the resettable fuse and / or the second end of the resettable fuse, and a second end connected to the ground end.

[0025] In some exemplary embodiments, the filtering circuit comprises:

[0026] at least one first sub-circuit, connected to the second protection circuit and the ground terminal, and configured to filter out common-mode interference of the input power supply;

[0027] The second sub-circuit is connected to the at least one first sub-circuit, the ground terminal and the output terminal, and is configured to filter the differential mode interference of the input power supply to generate the output power supply.

[0028] In some exemplary embodiments, the circuit further comprises: a power ground terminal; the at least one first sub-circuit comprises: a common-mode filter inductor, a fourth capacitor, a fifth capacitor, and a sixth capacitor;

[0029] The common mode filter inductor comprises a first coil and a second coil, the first coil is connected to the second protection circuit and the second sub-circuit, and the second coil is connected to the ground terminal;

[0030] The fourth capacitor has a first end connected to the second protection circuit and a second end connected to the ground end;

[0031] The fifth capacitor has a first end connected to the second sub-circuit, and a second end connected to the sixth capacitor and the power ground end;

[0032] The sixth capacitor has a first end connected to the fifth capacitor and the power ground end, and a second end connected to the ground end.

[0033] In some exemplary embodiments, the second sub-circuit includes: a first inductor, a second inductor, a seventh capacitor, and an eighth capacitor;

[0034] The first inductor has a first end connected to the at least one first sub-circuit and a second end connected to the output end;

[0035] The seventh capacitor has a first end connected to the at least one first sub-circuit, and a second end connected to the ground end;

[0036] The eighth capacitor has a first end connected to the output end and a second end connected to the second inductor;

[0037] The second inductor has a first end connected to the eighth capacitor, and a second end connected to the ground.

[0038] In some exemplary embodiments, the circuit further comprises:

[0039] A ninth capacitor has a first end connected to the power ground end, and a second end connected to the ground end.

[0040] In some exemplary embodiments, the circuit further comprises:

[0041] A third inductor has a first end connected to the first protection circuit, and a second end connected to the second protection circuit.

[0042] Based on the same concept, the present application also provides an electromagnetic shielding protection device, comprising the electromagnetic shielding protection circuit as described in any of the above items.

[0043] From the above, it can be seen that the present application provides an electromagnetic shielding protection circuit and device. The present application receives the input power supply at the input end through a MOS transistor, and the on-resistance of the MOS transistor is only 20mΩ of actual loss. Under the same current conditions, the power consumption of the circuit is significantly reduced, and no external heat sink is required, thereby solving the problems of voltage drop and excessive power consumption in the existing diode power supply anti-reverse connection solution. At the same time, through the solution of the present application, even if the current of the input power supply is large, the power consumption of the circuit of the present application is still smaller than that of the diode solution, and is more suitable for high current applications. Finally, through the two-stage protection circuit and the filtering circuit, the common-mode and differential-mode interference are well suppressed, and with the selection of low-noise components, the influence of power supply electromagnetic interference (EMI) can be effectively reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the related technologies, the drawings required for use in the embodiments or the related technical descriptions are briefly introduced below. Obviously, the drawings described below are only embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0045] Figure 1 A structural schematic diagram of a protection circuit provided in an embodiment of the present application is shown.

[0046] Figure 2 A schematic diagram of the structure of another protection circuit provided in an embodiment of the present application is shown.

[0047] Figure 3 A structural block diagram of an exemplary circuit provided in an embodiment of the present application is shown.

[0048] Figure 4 A specific structural schematic diagram of an exemplary circuit provided in an embodiment of the present application is shown.

[0049] Figure 5 A schematic structural diagram of an anti-reverse connection circuit provided in an embodiment of the present application is shown.

[0050] Figure 6 A schematic diagram of the structure of a first protection circuit provided in an embodiment of the present application is shown.

[0051] Figure 7 A schematic diagram of the structure of a second protection circuit provided in an embodiment of the present application is shown.

[0052] Figure 8 A schematic diagram of the structure of the first sub-circuit provided in an embodiment of the present application is shown.

[0053] Fig. 9 A schematic diagram of the structure of the second sub-circuit provided in an embodiment of the present application is shown.

[0054] Fig.10 A schematic diagram of the structure of the connection between the ground terminal and the power ground terminal provided in an embodiment of the present application is shown. DETAILED DESCRIPTION

[0055] In order to make the purpose, technical solutions and advantages of this specification more clear, this specification is further described in detail below in combination with specific embodiments and with reference to the accompanying drawings.

[0056] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the embodiments of the present application should be understood by people with ordinary skills in the field to which the present application belongs. The "first", "second" and similar words used in the embodiments of the present application do not represent any order, quantity or importance, but are only used to distinguish different components. "Including" or "comprising" and similar words mean that the elements, objects or method steps appearing before the word cover the elements, objects or method steps listed after the word and their equivalents, without excluding other elements, objects or method steps. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0057] As described in the background technology section, in the related art, diodes or diode bridges are generally used for corresponding protection.

[0058] In one embodiment, the DC power input reverse connection protection circuit generally uses the unidirectional conductivity of a diode to implement reverse connection protection. The specific circuit is as follows: Figure 1 As shown. Figure 1 As shown, a series diode protects the system from reverse polarity, but the diode has a 0.7V voltage drop.

[0059] This connection method is simple and reliable, but it has a great impact on power consumption when inputting large current. When the input current rating is 2A, if Onsemi's fast recovery diode MUR3020PT is selected, the rated tube voltage drop is 0.7V, then the power consumption must at least reach: Pd = 2A × 0.7V = 1.4W, which is inefficient and generates a lot of heat, so a heat sink must be added.

[0060] In another embodiment, if Figure 2 As shown, the circuit can be protected by a diode bridge. This circuit uses four diodes to protect the input from reverse connection. The external power supply can work normally when it is connected forward or reverse, but two diodes are turned on at the same time, so the power consumption is twice that of the single diode in the previous embodiment.

[0061] This circuit does not distinguish between positive and negative poles for external interfaces. The disadvantages of these solutions are mainly reflected in: the voltage drop on the diode consumes energy. When the input current is 2A, Figure 1 The circuit power consumption in is 1.4W. Figure 2 The power consumption of the circuit is 2.8W, which is Figure 1 The circuit shown is 1x higher, resulting in lower efficiency and higher heat generation.

[0062] It can be seen that the design of the diode reverse connection protection circuit utilizes the unidirectional conductivity of the diode. When the power supply is connected correctly, the diode is turned on and allows current to flow; when the power supply is reversed, the diode is turned off and prevents the current from flowing, thereby protecting the circuit from damage. However, this design also has some disadvantages: (1) Voltage drop problem: The diode will produce a voltage drop of about 0.7V when it is forward-conducting, which may be a problem for low-voltage circuits because it may cause insufficient load voltage. (2) Power consumption and heat generation: When the current passing through the diode is large (for example, 2A), the voltage drop on the diode will cause a large power consumption (for example, 1.4W), which will cause heat generation problems and may require additional heat dissipation measures. (3) Not suitable for high current applications: Due to the forward voltage drop and power consumption of the diode, this anti-reverse connection circuit is not suitable for high current applications because the power consumption will increase significantly at high currents. (4) EMI problem: In some designs using charge pump ideal diode controllers, due to the need for fast switching, the switching frequency may reach more than 10MHz, which may cause higher EMI problems.

[0063] In view of the above-mentioned actual situation, an embodiment of the present application provides an electromagnetic shielding protection circuit. The present application receives the input power supply at the input end through a MOS transistor, and the on-resistance of the MOS transistor is only 20mΩ of actual loss. Under the same current conditions, the power consumption of the circuit is significantly reduced, and no external heat sink is required, thereby solving the problems of voltage drop and excessive power consumption in the existing diode power supply anti-reverse connection solution. At the same time, through the solution of the present application, even if the current of the input power supply is large, the power consumption of the circuit of the present application is still smaller than that of the diode solution, and it is more suitable for high-current applications. Finally, through the two-stage protection circuit and the filtering circuit, the common-mode and differential-mode interference are well suppressed, and with the selection of low-noise components, the influence of power supply electromagnetic interference (EMI) can be effectively reduced.

[0064] after, Figure 3 shows a structural block diagram of an exemplary circuit provided in an embodiment of the present application, Figure 4 A specific structural schematic diagram of an exemplary circuit provided in an embodiment of the present application is shown.

[0065] like Figure 3 and Figure 4 As shown, the electromagnetic shielding protection circuit exemplarily proposed in the embodiment of the present application includes an input terminal VIN, an output terminal VOUT, a ground terminal GND, an anti-reverse connection circuit 110, a first protection circuit 120, a second protection circuit 130 and a filter circuit 140; wherein the anti-reverse connection circuit 110 is connected to the input terminal VIN and the ground terminal GND, and is configured to use a MOS transistor in the circuit to receive the input power supply of the input terminal VIN, and disconnect when the input power supply is reversely connected; the first protection circuit 120 is connected to the anti-reverse connection circuit 110 and the ground terminal GND, and is configured to perform a voltage shock exceeding a first threshold on the input power supply; the second protection circuit 130 is connected to the first protection circuit 120 and the ground terminal GND, and is configured to perform a current shock exceeding a second threshold on the input power supply; the filter circuit 140 is connected to the second protection circuit 130, the ground terminal GND and the output terminal VOUT, and is configured to filter out differential mode interference and common mode interference on the input power supply, and generate an output power supply to be output through the output terminal VOUT.

[0066] In this embodiment, the input terminal VIN is generally an input power terminal, which can generally be connected to an external power grid or other power source and may have a higher voltage. The output terminal is generally an output power terminal. Since the main function of this application is to protect the circuit, the voltage, current and other parameters of the output power terminal may be the same or similar to those of the input terminal VIN. The ground terminal GND is a ground wire, which can generally be regarded as a 0V voltage terminal.

[0067] Afterwards, if Figure 5As shown, it is a schematic diagram of the structure of the anti-reverse connection circuit 110. The anti-reverse connection circuit 110 may further include: a MOS transistor MOS, a first resistor R1, a second resistor R2, a third resistor R3, a first capacitor C1, a second capacitor C2 and a first transient voltage suppression diode T1; the MOS transistor MOS, its first electrode is connected to the input terminal VIN, its second electrode is connected to the first protection circuit 120, and its control electrode is connected to the ground terminal GND through the third resistor R3; the first resistor R1, the first end is connected to the first electrode of the MOS transistor MOS, and the second end is connected to the first capacitor C1; the first capacitor C1, the first end is connected to the first resistor R1, and the second end is connected to the second electrode of the MOS transistor MOS; the second resistor R2, the first end is connected to the second electrode of the MOS transistor MOS, and the second end is connected to the control electrode of the MOS transistor MOS; the first transient voltage suppression diode T1, the first end is connected to the second electrode of the MOS transistor MOS, and the second end is connected to the control electrode of the MOS transistor; the second capacitor C2, the first end is connected to the second electrode of the MOS transistor MOS, and the second end is connected to the control electrode of the MOS transistor MOS.

[0068] It should be noted that the control electrode of the transistor structure appearing in this embodiment and subsequent embodiments generally corresponds to the gate (G) of the transistor, and the first electrode and the second electrode correspond to the source (S) and drain (D) of the transistor. At the same time, the MOS transistors used in the embodiments of the present application can be thin film transistors or field effect transistors or other devices with the same characteristics, and the thin film transistor can be an oxide semiconductor transistor. According to the role in the circuit, the transistors used in the embodiments of the present application are mainly switching transistors. Since the source and drain of the switching transistor are symmetrical, the source and drain are interchangeable, and then in this solution, one of the source and drain is called the first electrode, the other of the source and drain is called the second electrode, and the gate is called the control electrode.

[0069] Later, transient voltage suppressor diode TVS (Transient Voltage Suppressor) is an overvoltage protection device with bidirectional voltage stabilization characteristics and bidirectional negative resistance characteristics, similar to a varistor. It is used in various AC and DC power supply circuits to suppress instantaneous overvoltage. When a surge pulse voltage appears instantly in the protected circuit, the bidirectional breakdown diode can quickly break down from a high resistance state to a low resistance state, shunting and clamping the surge voltage, thereby protecting the components in the circuit from being damaged by the instantaneous surge pulse voltage.

[0070] In this embodiment, the MOS transistor MOS is connected in series to the input terminal VIN through the first pole and the second pole, the second resistor R2 and the third resistor R3 provide voltage bias for the MOS transistor MOS, and the switching characteristics of the MOS transistor MOS are used to control the conduction and disconnection of the circuit to prevent the reverse connection of the power supply from causing damage to the load. Afterwards, the first transient voltage suppression diode T1 is used to protect the control pole of the MOS transistor MOS and clamp the external level exceeding the threshold voltage. The first resistor R1 and the first capacitor C1 are used to protect the circuit. When the circuit is not working, these two devices can filter the AC signal and release the energy of the subsequent capacitive load or inductive load. The second capacitor C2 has a similar function to the first capacitor C1, and both are used to protect the circuit. The difference is that the first capacitor C1 protects between the first pole and the second pole of the MOS transistor MOS, and the second capacitor C2 protects between the second pole and the control pole of the MOS transistor MOS.

[0071] In a more specific application scenario, when the power supply is connected in the positive direction, the current will flow to the body diode of the MOS transistor MOS. Because the power supply voltage is higher than the forward bias voltage of the body diode, the body diode will be turned on. The voltage at the source of the MOSFET will be the battery voltage minus the body diode voltage drop. Since the third resistor R3 provides the VGS voltage, VGS is negative at this time, and the MOS transistor MOS is saturated and turned on. When the power supply is reversed, the control pole of the MOS transistor MOS is at a high level, and the MOS transistor MOS cannot be turned on, so it plays an anti-reverse connection role. The on-resistance Rds(on) of the MOS transistor MOS is only 20mΩ, and the actual loss is very small. Taking a current of 2A as an example, the power consumption is (2×2)×0.02=0.08W, and no external heat sink is required, which solves the problems of large voltage drop and high power consumption in the existing diode power supply anti-reverse connection solution.

[0072] Afterwards, it should be emphasized that according to the characteristics of MOS transistors, transistors can be divided into N-type and P-type. The P-type transistor is turned on when the gate is at a low level and is turned off when the gate is at a high level; the N-type transistor is turned on when the gate is at a high level and is turned off when the gate is at a low level.

[0073] In this article, the MOS transistor is described by taking an N-type transistor as an example, which is a preferred solution for easy implementation in this embodiment, and it does not limit the technical solution of the present invention. It should be known to those skilled in the art that simply changing the type of each transistor (N-type or P-type) and changing the positive and negative polarity of the output voltage of each power supply terminal to achieve the same technical solution of turning on or off the transistor as in this embodiment, all belong to the protection scope of this application. The specific situation will not be illustrated one by one here.

[0074] In some embodiments, Figure 4 , Figure 6 As shown, the electromagnetic shielding protection circuit may further include: a power ground terminal PGND; further, the first protection circuit 120 includes: a first varistor R4, a second varistor R5, a third varistor R6 and a gas discharge tube D1; the first varistor R4, the first end is connected to the anti-reverse connection circuit 110 and the second protection circuit 130, and the second end is connected to the ground terminal GND; the second varistor R5, the first end is connected to the anti-reverse connection circuit 110 and the second protection circuit 130, and the second end is connected to the third varistor R6 and the gas discharge tube D1; the third varistor R6, the first end is connected to the second varistor R5, and the second end is connected to the ground terminal GND; the gas discharge tube D1, the first end is connected to the second varistor R5, and the second end is connected to the power ground terminal GND.

[0075] Among them, the power ground terminal PGND is a ground wire specially used for large current loops, which is different from GND and is used to reduce noise and interference in large current loops. In some power management chips, PGND may be connected to GND, but in high-power applications, they may be separated to optimize performance. The gas discharge tube D1 refers to a lightning arrester or antenna switch tube used for overvoltage protection. There are two or more electrodes in the tube, which is filled with a certain amount of inert gas. The gas discharge tube is a gap-type lightning protection element, which is used in lightning protection of communication systems.

[0076] In a more specific application scenario, the first protection circuit 120 is composed of a first varistor R4, a second varistor R5, a third varistor R6 and a gas discharge tube D1, wherein the first varistor R4 is mainly used for differential mode protection, and the second varistor R5, the third varistor R6 and the gas discharge tube D1 are mainly used for common mode protection. The specific first protection circuit 120 mainly responds to interference caused by large voltage changes, such as lightning strikes and surges.

[0077] Then, in some embodiments, as Figure 4 and Figure 7As shown, after passing through the first protection circuit 120, the input power will flow to the second protection circuit 130, wherein the second protection circuit 130 can be composed of a resettable fuse F1, at least one second transient voltage suppression diode T2 to T3 and at least one third capacitor C3 to C5, wherein the resettable fuse F1 has a first end connected to the first protection circuit 120, and a second end connected to the filter circuit 140; the at least one second transient voltage suppression diode T2 has a first end connected to the second end of the resettable fuse F1, and a second end connected to the ground terminal GND; the at least one third capacitor C3 has a first end connected to the first end of the resettable fuse F1 and / or the second end of the resettable fuse F1, and a second end connected to the ground terminal GND.

[0078] In this embodiment, the fuse current limiting protection is widely used in circuits such as switching power supplies. The resettable fuse F1 selected in this application can be PTC, which is a kind of recoverable fuse. The working principle of PTC is that when an abnormal overcurrent occurs in the circuit, the large current flowing through the PTC will generate a lot of heat, causing the polymer matrix material to expand, thereby separating the conductive particles, cutting off the conductive path, and the PTC resistance rises sharply, limiting the abnormal overcurrent; after the abnormal overcurrent fault is cleared, the polymer matrix material cools and shrinks, re-forming the conductive path, and the PTC resistance returns to a low resistance state, realizing automatic recovery without manual replacement. Transient Voltage Suppressor (TVS) is a new type of highly efficient circuit protection device commonly used. It has an extremely fast response time (sub-nanosecond level) and a very high surge absorption capacity. Under normal operating voltage, the TVS diode is in a high-resistance state and is basically non-conductive. When the reverse voltage of the TVS exceeds its breakdown voltage, the impedance of the TVS drops rapidly, allowing a large current to pass through and clamping the voltage at a lower level. When the TVS diode is impacted by a reverse transient high-voltage spike pulse, it can quickly absorb most of the energy and increase the clamping voltage from the breakdown voltage to the maximum clamping voltage. As the pulse current decreases exponentially, the clamping voltage also gradually decreases and returns to its original state, effectively protecting electronic circuit components from various forms of pulse impacts. Afterwards, at least one third capacitor T3 to T5 that can be set at both ends of the resettable fuse F1 is mainly used for filtering and filtering out the alternating current in the circuit. In different application scenarios, the number and setting position can be adjusted according to specific needs.

[0079] It can be seen that the second protection circuit 130 is mainly used to protect the circuit from large current shocks.

[0080] Afterwards, if Figure 4As shown, the filtering circuit 140 may further include: at least one first sub-circuit 141, connected to the second protection circuit 130 and the ground terminal GND, and configured to filter out common-mode interference of the input power supply; a second sub-circuit 142, connected to the at least one first sub-circuit 141, the ground terminal GND and the output terminal VOUT, and configured to filter out differential-mode interference of the input power supply to generate the output power supply.

[0081] Among them, for the first subcircuit 141, considering different needs in different scenarios, multiple first subcircuits 141 can be set. Each additional first subcircuit 141 will increase the common mode voltage of the circuit, but this increase is not linear. According to experiments, the common mode voltage of one first subcircuit 141 can reach 1000KV, and two first subcircuits 141 can reach 2000KV, but the effect of the increase is significantly reduced from the third one. Considering the cost performance, Figure 4 As shown, it is most cost-effective to set two first sub-circuits 141. Of course, in different specific scenarios, the number of the first sub-circuits 141 can be adjusted arbitrarily according to the scenario requirements.

[0082] Afterwards, if Figure 4 and Figure 8 As shown, it is a schematic diagram of the structure of a first subcircuit 141. The at least one first subcircuit 141 may include: a common mode filter inductor LCM1, a fourth capacitor C6, a fifth capacitor C7 and a sixth capacitor C8; the common mode filter inductor LCM1 includes a first coil Q1 and a second coil Q2, the first coil Q1 is connected to the second protection circuit 130 and the second subcircuit 142, and the second coil Q2 is connected to the ground terminal GND; the fourth capacitor C6, a first end is connected to the second protection circuit 130, and a second end is connected to the ground terminal GND; the fifth capacitor C7, a first end is connected to the second subcircuit 142, and a second end is connected to the sixth capacitor C8 and the power ground terminal PGND; the sixth capacitor C8, a first end is connected to the fifth capacitor C7 and the power ground terminal PGND, and a second end is connected to the ground terminal GND.

[0083] Among them, the fourth capacitor C6 is a differential mode filter capacitor, which mainly filters out differential mode interference, and its filtering frequency band can cover 150kHz-500kHz. The fifth capacitor C7 and the sixth capacitor C8 are common mode filter capacitors, which provide a low impedance loop for common mode interference, and its filtering frequency band can cover 10MHz-30MHz. The common mode filter inductor LCM1 can suppress common mode interference, and its filtering frequency band can cover 10MHz-30MHz.

[0084] It should be noted that differential-mode interference and common-mode interference are two common forms of electromagnetic interference in electronic engineering, and they have different effects on the normal operation of electronic equipment. Among them, differential-mode interference refers to the interference voltage existing between the signal line and its return line, which is characterized by the equal amplitude and opposite direction of the interference current on the two wires. This interference is symmetrical and directly affects the transmission quality of the signal because it is directly superimposed on the useful signal. Differential-mode interference can cause signal distortion, data errors and communication interruption, especially in long-distance transmission or high-speed data transmission. Methods for suppressing differential-mode interference include the use of differential-mode inductors and differential-mode capacitors. Common-mode interference is interference transmitted between the wire and the ground (casing), which is asymmetric interference. It is defined as an undesirable potential difference between any current-carrying conductor and the reference ground. The current of common-mode interference is not necessarily equal, but the direction (phase) is the same. Common-mode interference itself generally does not cause harm to the equipment, but if common-mode interference is converted into differential-mode interference, the interference will be serious because the useful signals are all differential-mode signals. Methods for suppressing common mode interference include using common mode inductors (common mode chokes) and shielding signal lines.

[0085] Common mode filter inductor LCM1 is an electromagnetic component specially used to suppress common mode interference. Common mode interference refers to the noise voltage between two or more wires relative to the reference ground (usually the chassis or power ground) in an electrical system. This interference is usually caused by external electromagnetic field induction, power supply fluctuations or electromagnetic radiation between devices, which may cause data errors, signal distortion and device performance degradation.

[0086] Combined with the above description, in Figure 4 Two first sub-circuits 141 are provided in the circuit shown, and for the second first sub-circuit 141, capacitor C9 is the fourth capacitor in the second first sub-circuit 141, capacitor C10 is the fifth capacitor in the second first sub-circuit 141, capacitor C11 is the sixth capacitor in the second first sub-circuit 141, and common-mode filter inductor LCM2 corresponds to common-mode filter inductor LCM1.

[0087] Afterwards, if Figure 4 and Fig. 9As shown, it is a schematic diagram of the structure of the second subcircuit 142. The second subcircuit 142 may include: a first inductor U1, a second inductor U2, a seventh capacitor C12 and an eighth capacitor C13; the first inductor U1, the first end is connected to the at least one first subcircuit 141, and the second end is connected to the output terminal VOUT; the seventh capacitor C12, the first end is connected to the at least one first subcircuit 141, and the second end is connected to the ground terminal GND; the eighth capacitor C13, the first end is connected to the output terminal VOUT, and the second end is connected to the second inductor U2; the second inductor U13, the first end is connected to the eighth capacitor C13, and the second end is connected to the ground terminal GND. Among them, the seventh capacitor C12 and the eighth capacitor C13 are differential mode filter capacitors, and the first inductor U1 and the second inductor U2 are differential mode inductors, which are mainly used to filter out differential mode interference.

[0088] Furthermore, the power ground terminal PGND can be connected to the ground terminal GND to provide a leakage path for the output terminal VOUT interference. Fig.10 As shown, the power ground terminal PGND can be connected to the ground terminal GND through the ninth capacitor C14. In a more specific scenario, the ninth capacitor C14 here can be a capacitor of 1000pF. That is, in some embodiments, the circuit further includes: a ninth capacitor C14, a first end of which is connected to the power ground terminal PGND, and a second end of which is connected to the ground terminal GND.

[0089] In some embodiments, in addition to preventing sudden large currents, current mutations can be further prevented. Figure 4 As shown, a third inductor U3 may be provided between the first protection circuit 120 and the second protection circuit 130 to cope with the current mutation. That is, in some embodiments, the circuit further includes: a third inductor U3, a first end of which is connected to the first protection circuit 120, and a second end of which is connected to the second protection circuit 130.

[0090] From the above, it can be seen that the electromagnetic shielding protection circuit provided by the present application receives the input power supply at the input end through a MOS transistor, and the on-resistance of the MOS transistor is only 20mΩ of actual loss. Under the same current conditions, the power consumption of the circuit is significantly reduced, and no external heat sink is required, thereby solving the problems of voltage drop and excessive power consumption in the existing diode power supply anti-reverse connection solution. At the same time, through the solution of the present application, even if the current of the input power supply is large, the power consumption of the circuit of the present application is still smaller than that of the diode solution, and is more suitable for high-current applications. Finally, through the two-stage protection circuit and the filtering circuit, the common-mode and differential-mode interference are well suppressed, and with the selection of low-noise components, the influence of power supply electromagnetic interference (EMI) can be effectively reduced.

[0091] Based on the same concept, the present application also provides an electromagnetic shielding protection device, including the electromagnetic shielding protection circuit as described in any of the aforementioned embodiments.

[0092] The electromagnetic shielding protection device of the above embodiment is used to apply the corresponding electromagnetic shielding protection circuit in the above embodiment, and has the beneficial effects of the embodiment of the corresponding electromagnetic shielding protection circuit, which will not be described in detail here.

[0093] In a specific application scenario, the electromagnetic shielding protection device can be a circuit board (PCB board), or a hierarchical structure or device tool directly drawn with an electromagnetic shielding protection circuit. Specific situations are not given one by one here.

[0094] Those skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of the present disclosure (including the claims) is limited to these examples. Based on the concept of the present disclosure, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of the different aspects of the embodiments of the present disclosure as described above, which are not provided in detail for the sake of simplicity.

[0095] In addition, to simplify the description and discussion, and in order not to make the embodiments of the present disclosure difficult to understand, the known power / ground connections to the integrated circuit (IC) chips and other components may or may not be shown in the provided figures. In addition, the device can be shown in the form of a block diagram to avoid making the embodiments of the present disclosure difficult to understand, and this also takes into account the fact that the details of the implementation of these block diagram devices are highly dependent on the platform on which the embodiments of the present disclosure will be implemented (that is, these details should be fully within the scope of understanding of those skilled in the art). Where specific details (e.g., circuits) are set forth to describe exemplary embodiments of the present disclosure, it is apparent to those skilled in the art that the embodiments of the present disclosure can be implemented without these specific details or with changes in these specific details. Therefore, these descriptions should be considered illustrative rather than restrictive.

[0096] Although the present disclosure has been described in conjunction with specific embodiments of the present disclosure, many replacements, modifications and variations of these embodiments will be apparent to those skilled in the art from the foregoing description. For example, other memory architectures (e.g., dynamic RAM (DRAM)) may use the embodiments discussed.

[0097] The embodiments of the present disclosure are intended to cover all such substitutions, modifications and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the embodiments of the present disclosure should be included in the scope of protection of the present disclosure.

Claims

1. An electromagnetic shielding protection circuit, characterized in that: include: Input terminal, output terminal, ground terminal, anti-reverse connection circuit, first protection circuit, second protection circuit and filter circuit; The anti-reverse connection circuit is connected to the input terminal and the ground terminal, and is configured to receive the input power of the input terminal by using the MOS transistor in the circuit, and disconnect when the input power is reversely connected; The first protection circuit is connected to the anti-reverse connection circuit and the ground terminal, and is configured to perform a voltage shock exceeding a first threshold on the input power supply; The second protection circuit is connected to the first protection circuit and the ground terminal, and is configured to impact the input power supply with a current exceeding a second threshold; The filter circuit is connected to the second protection circuit, the ground terminal and the output terminal, and is configured to filter out differential mode interference and common mode interference of the input power supply, and generate output power supply to be output through the output terminal.

2. The circuit according to claim 1, characterized in that The anti-reverse connection circuit comprises: a MOS transistor, a first resistor, a second resistor, a third resistor, a first capacitor, a second capacitor and a first transient voltage suppression diode; The MOS transistor has a first electrode connected to the input terminal, a second electrode connected to the first protection circuit, and a control electrode connected to the ground terminal via a third resistor; The first resistor has a first end connected to the first electrode of the MOS transistor and a second end connected to the first capacitor; The first capacitor has a first end connected to the first resistor and a second end connected to the second electrode of the MOS transistor; The second resistor has a first end connected to the second electrode of the MOS transistor and a second end connected to the control electrode of the MOS transistor; The first transient voltage suppression diode has a first end connected to the second electrode of the MOS transistor and a second end connected to the control electrode of the MOS transistor; The second capacitor has a first end connected to the second electrode of the MOS transistor, and a second end connected to the control electrode of the MOS transistor.

3. The circuit according to claim 1, characterized in that Also includes: Power ground terminal; The first protection circuit comprises: a first varistor, a second varistor, a third varistor and a gas discharge tube; The first varistor has a first end connected to the anti-reverse connection circuit and the second protection circuit, and a second end connected to the ground end; The second varistor has a first end connected to the anti-reverse connection circuit and the second protection circuit, and a second end connected to the third varistor and the gas discharge tube; The third varistor has a first end connected to the second varistor and a second end connected to the ground end; The gas discharge tube has a first end connected to the second varistor and a second end connected to the power ground.

4. The circuit according to claim 1, characterized in that The second protection circuit comprises: a resettable fuse, at least one second transient voltage suppression diode and at least one third capacitor; The resettable fuse has a first end connected to the first protection circuit and a second end connected to the filter circuit; The at least one second transient voltage suppression diode has a first end connected to the second end of the resettable fuse and a second end connected to the ground end; The at least one third capacitor has a first end connected to the first end of the resettable fuse and / or the second end of the resettable fuse, and a second end connected to the ground end.

5. The circuit according to claim 1, characterized in that The filtering circuit comprises: at least one first sub-circuit, connected to the second protection circuit and the ground terminal, and configured to filter out common-mode interference of the input power supply; The second sub-circuit is connected to the at least one first sub-circuit, the ground terminal and the output terminal, and is configured to filter the differential mode interference of the input power supply to generate the output power supply.

6. The circuit according to claim 5, characterized in that Also includes: Power ground terminal; The at least one first sub-circuit comprises: a common mode filter inductor, a fourth capacitor, a fifth capacitor and a sixth capacitor; The common mode filter inductor comprises a first coil and a second coil, the first coil is connected to the second protection circuit and the second sub-circuit, and the second coil is connected to the ground terminal; The fourth capacitor has a first end connected to the second protection circuit and a second end connected to the ground terminal; The fifth capacitor has a first end connected to the second sub-circuit, and a second end connected to the sixth capacitor and the power ground end; The sixth capacitor has a first end connected to the fifth capacitor and the power ground end, and a second end connected to the ground end.

7. The circuit according to claim 5, characterized in that The second sub-circuit comprises: a first inductor, a second inductor, a seventh capacitor and an eighth capacitor; The first inductor has a first end connected to the at least one first sub-circuit and a second end connected to the output end; The seventh capacitor has a first end connected to the at least one first sub-circuit and a second end connected to the ground end; The eighth capacitor has a first end connected to the output end and a second end connected to the second inductor; The second inductor has a first end connected to the eighth capacitor, and a second end connected to the ground.

8. The circuit according to claim 3 or 6, characterized in that: Also includes: A ninth capacitor has a first end connected to the power ground end, and a second end connected to the ground end.

9. The circuit according to claim 1, characterized in that Also includes: A third inductor has a first end connected to the first protection circuit, and a second end connected to the second protection circuit.

10. An electromagnetic shielding protection device, characterized in that: It comprises the electromagnetic shielding protection circuit as described in any one of claims 1 to 9.

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