EMI filter power supply for network communication products

Abstract

This utility model discloses an EMI filtering power supply for network communication products, including a circuit board. The circuit board has a pre-stage rectifier and filter circuit connected to the mains power. The circuit board also includes the following circuits: a differential-mode filter circuit connected to the output of the pre-stage rectifier and filter circuit; a constant current control circuit connected to the output of the differential-mode filter circuit; a transformer circuit connected to the output of the constant current control circuit; a post-stage rectifier and filter circuit connected to the output of the transformer circuit; and an input / output network port circuit connected to the post-stage rectifier and filter circuit. This utility model has a reasonable structural design. Its input stage only uses the pre-stage rectifier and filter circuit, which helps reduce costs and save space. The inclusion of a differential-mode filter circuit effectively shields conducted and radiated interference, ensuring the circuit remains within standard ranges, improving operational stability and reliability, and meeting the needs of various applications.

Description

Technical Field

[0001] This utility model belongs to the field of power supply technology, specifically relating to an EMI filter power supply for network communication products. Background Technology

[0002] Network communication products require corresponding power supplies during use. The switching process of these power supplies generates electromagnetic interference. The surge current and voltage spikes generated by the power supply form interference sources. Existing similar products require a two-stage filtering network in the front stage to meet EMI requirements. This not only greatly increases the cost of circuit use but also makes troubleshooting and maintenance difficult. In addition, traditional technology requires the addition of a magnetic ring inductor to meet radiation standards, which also increases the difficulty of setup and the cost of use. Utility Model Content

[0003] The purpose of this invention is to provide an EMI filter power supply for network communication products with a reasonable structural design that helps reduce costs.

[0004] The technical solution for achieving the purpose of this utility model is an EMI filter power supply for a network communication product, including a circuit board. The circuit board is provided with a pre-stage rectifier and filter circuit connected to the mains power supply. The circuit board is also provided with the following circuits:

[0005] A differential-mode filter circuit is connected to the output of the preceding rectifier filter circuit and is used to shield the mains power from power interference to the network communication products.

[0006] A constant current control circuit is connected to the output terminal of the differential mode filter circuit and is used to control the output DC power.

[0007] The transformer circuit is connected to the output terminal of the constant current control circuit to achieve voltage regulation.

[0008] The subsequent rectifier and filter circuit is connected to the output terminal of the transformer circuit and is used to rectify and filter the AC component of the transformer circuit into a DC component for the load.

[0009] The input / output network port circuit is connected to the subsequent rectifier and filter circuit to supply power to the load.

[0010] A further preferred embodiment is that the differential mode filter circuit includes a first capacitor, a second capacitor, and a first inductor;

[0011] The first capacitor and the second capacitor are connected in parallel. The positive terminal of the first capacitor is connected to the output terminal of the pre-stage rectifier and filter circuit, and the positive terminal of the second capacitor is connected to the end of the constant current control circuit. The first inductor is connected in series between the positive terminals of the first capacitor and the second capacitor, and the negative terminals of the first capacitor and the second capacitor are grounded.

[0012] Further preferably, the constant current control circuit includes a constant current drive chip, an output no-load voltage sampling circuit connected to the constant current drive chip, an absorption circuit connected to the constant current drive chip for absorbing the peak motor of the freewheeling diode, and a first safety capacitor for reducing interference in the circuit is provided between the ground pin of the constant current drive chip and the ground pin of the input / output network port circuit.

[0013] The freewheeling diode is used to reduce electromagnetic interference in the circuit.

[0014] A further preferred embodiment is that the constant current driver chip is model KP23132M.

[0015] A further preferred embodiment is that the voltage across the first safety capacitor is less than or equal to 5V.

[0016] A further preferred embodiment is that the circuit board is provided with a surge protection circuit, which is located between the mains power and the pre-stage rectifier and filter circuit.

[0017] A further preferred embodiment is that the surge protection circuit includes a varistor and a fuse resistor;

[0018] The fuse resistor is connected in series at the positive input terminal of the pre-stage rectifier and filter circuit, and the varistor is connected in parallel between the positive and negative input terminals of the pre-stage rectifier and filter circuit.

[0019] This utility model has positive effects: its structure is reasonably designed, and its input end only uses a pre-stage rectifier and filter circuit, which helps to reduce costs and save space. Moreover, its transformer circuit has fewer copper shielding layers compared to traditional transformers, which helps to further reduce costs. At the same time, its differential mode filter circuit can effectively shield conducted and radiated interference, so that the circuit can reach the standard range, improve the stability and reliability of use, and meet the needs of different situations. Attached Figure Description

[0020] To make the content of this utility model easier to understand, the present utility model will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein:

[0021] Figure 1 This is a structural block diagram of the present invention;

[0022] Figure 2 This is a schematic diagram of the specific circuit of this utility model.

[0023] Figure labeling: 1. Pre-stage rectifier and filter circuit; 2. Differential-mode filter circuit; 3. Constant current control circuit; 4. Transformer circuit; 5. Post-stage rectifier and filter circuit; 6. Input / output network port circuit; 7. Surge protection circuit; 8. Mains power. Detailed Implementation

[0024] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0025] Example

[0026] See Figures 1 to 2 As shown, an EMI filter power supply for a network communication product includes a circuit board. The circuit board has a pre-stage rectifier and filter circuit 1 connected to the mains power supply 8. The circuit board also includes the following circuits:

[0027] Differential mode filter circuit 2 is connected to the output terminal of the pre-stage rectifier filter circuit and is used to shield the mains power from power interference to the network communication product.

[0028] The constant current control circuit 3 is connected to the output terminal of the differential mode filter circuit and is used to control the output DC power.

[0029] Transformer circuit 4 is connected to the output terminal of the constant current control circuit to achieve voltage regulation;

[0030] The post-stage rectifier and filter circuit 5 is connected to the output terminal of the transformer circuit and is used to rectify and filter the AC component of the transformer circuit into a DC component for the load.

[0031] The input / output network port circuit 6 is connected to the subsequent rectifier and filter circuit and is used to connect to the load. In actual application, it provides the load with the digital signal from the router or switch and the power supplied by this device through the output network port.

[0032] The pre-stage rectifier and filter circuit includes a rectifier bridge DB1, which converts the AC voltage and current input to the rectifier and filter module via the pre-stage common-mode module into DC voltage and current.

[0033] In some embodiments, a copper foil is provided on the back of the circuit board, and the copper foil is connected to the ground terminal of the constant current control circuit.

[0034] The differential-mode filter circuit includes a first capacitor EC1, a second capacitor EC2, and a first inductor L1. The first and second capacitors are connected in parallel. The positive terminal of the first capacitor is connected to the output terminal of the preceding rectifier filter circuit, and the positive terminal of the second capacitor is connected to the terminal of the constant current control circuit. The first inductor is connected in series between the positive terminals of the first and second capacitors, and the negative terminals of the first and second capacitors are grounded. Together, these three components form an LCπ-type filter circuit, used to filter out noise and oscillations in the signal from the preceding common-mode module, improving signal quality and stability, thereby enhancing circuit performance.

[0035] In practical applications, the constant current control circuit includes a constant current drive chip U1, an output no-load voltage sampling circuit connected to the constant current drive chip, an absorption circuit connected to the constant current drive chip for absorbing the peak motor of the freewheeling diode, and a first safety capacitor CY1 for reducing interference in the circuit is provided between the ground pin of the constant current drive chip and the ground pin of the input / output network port circuit; the freewheeling diode is used to reduce electromagnetic interference in the circuit.

[0036] The second pin of the constant current driver chip U1 is grounded; the third pin of the constant current driver chip U1 is connected to VDD; the fourth pin of the constant current driver chip U1 is grounded through resistors R5 and R4; pins 5, 6, 7, and 8 of the constant current driver chip U1 are connected to a high voltage; the first pin of the constant current driver chip U1 is grounded through the first sampling resistor R7 / R8 or the second sampling resistor R9; one end of the first safety capacitor CY1 is grounded, and the other end of the first safety capacitor CY1 is connected to the load ground. The model of the constant current driver chip is KP23132M.

[0037] The second resistors R7, R8, and R9 are used to adjust the output no-load voltage to prevent the output voltage from being too high; the third resistor R3 and capacitors C1 and C5 together form an absorption circuit to absorb the voltage spikes on the freewheeling diode D1; the first sampling resistors R5 and R4 are used to adjust the output current of the circuit, thereby adjusting the overall lamp power; the first safety capacitor CY1 is used to reduce interference in the circuit. The voltage across the first safety capacitor is less than or equal to 5V.

[0038] When the input voltage is detected at pin 3 of the constant current driver chip U1, the constant current driver chip U1 starts to work. The bus voltage is filtered by the fourth capacitor EC3, then through D3, through the load, through the transformer T1 circuit, and through the first sampling resistor R4 / R5 circuit back to the inside of the constant current driver chip U1, forming a power grid circuit.

[0039] A freewheeling diode snubber circuit is used to reduce electromagnetic interference in the circuit. The circuit includes fourth resistors R2 and R3, fourth capacitors C3 and C5, a freewheeling diode D1, and a transformer T1. The cathode of the freewheeling diode D1 is connected to the first output terminal of the rectifier bridge DB1, and the anode of D1 is connected to the input terminal of the transformer T1. One end of the fourth capacitor C3 and the fourth resistor R2 is connected to the output terminal of the transformer T1, and the other end of the fourth capacitors EC2 and EC1 is connected to the positive output terminal of the rectifier bridge DB1.

[0040] The fourth capacitor C4 is the output filter capacitor; the fourth resistor R4 is the load resistor, used to discharge the fourth capacitor EC4; the transformer T1 is used for energy storage and transformation; the freewheeling diode D1 is used to discharge excess energy on the transformer T1.

[0041] The post-stage rectifier and filter module is used to shield the power supply from interference from the load.

[0042] A surge protection circuit 7 is provided on the circuit board, located between the mains power supply and the pre-stage rectifier and filter circuit. The surge protection circuit includes a varistor VR1 and a fuse resistor F1; the fuse resistor F1 is connected in series at the positive input terminal of the pre-stage rectifier and filter circuit, and the varistor VR1 is connected in parallel between the positive and negative input terminals of the pre-stage rectifier and filter circuit. One end of the protection resistor F1 is connected to the live wire of the mains power supply, and the other end of the protection resistor F1 is connected to the input terminal of the pre-stage rectifier module and one end of the varistor VR1; the other end of the varistor VR1 is connected to the neutral wire of the mains power supply.

[0043] The fuse resistor F1 is connected in series with the live wire connection section to prevent short circuits in the downstream stage from directly affecting the input grid voltage; the varistor RV1 is used to absorb excessively high input peak voltage and excessive current when there is an excessive lightning strike; the second safety capacitor is used to reduce interference in the circuit.

[0044] The load can include a camera, and its connection method can be designed in different ways according to actual needs. The router or switch is connected to the input / output port module via a network cable, and the camera is connected to the output port module. During testing, the router and isolator must be grounded to ensure the entire product meets conduction and radiation standards.

[0045] This utility model has positive effects: its structure is reasonably designed, and its input end only uses a pre-stage rectifier and filter circuit, which helps to reduce costs and save space. Moreover, its transformer circuit has fewer copper shielding layers compared to traditional transformers, which helps to further reduce costs. At the same time, its differential mode filter circuit can effectively shield conducted and radiated interference, so that the circuit can reach the standard range, improve the stability and reliability of use, and meet the needs of different situations.

[0046] The standard parts used in this embodiment can be purchased directly from the market, and the non-standard structural parts described in the instruction manual can also be processed without any doubt based on existing technical common sense. At the same time, the connection methods of each component adopt mature conventional methods in the existing technology, and the machinery, parts and equipment all adopt conventional models in the existing technology, so they will not be described in detail here.

[0047] Obviously, the above embodiments of this utility model are merely examples for clearly illustrating this utility model, and are not intended to limit the implementation of this utility model. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively list all embodiments here. However, these obvious variations or modifications derived from the essential spirit of this utility model still fall within the protection scope of this utility model.

Claims

1. An EMI filtering power supply for a network communication product, comprising a circuit board, wherein the circuit board is provided with a pre-stage rectifier and filter circuit connected to the mains power, characterized in that: The circuit board is also equipped with the following circuits: A differential-mode filter circuit is connected to the output of the preceding rectifier filter circuit and is used to shield the mains power from power interference to the network communication products. A constant current control circuit is connected to the output terminal of the differential mode filter circuit and is used to control the output DC power. The transformer circuit is connected to the output terminal of the constant current control circuit to achieve voltage regulation. The subsequent rectifier and filter circuit is connected to the output terminal of the transformer circuit and is used to rectify and filter the AC component of the transformer circuit into a DC component for the load. The input / output network port circuit is connected to the subsequent rectifier and filter circuit to supply power to the load.

2. The EMI filtering power supply for a network communication product according to claim 1, characterized in that: The differential mode filter circuit includes a first capacitor, a second capacitor, and a first inductor; The first capacitor and the second capacitor are connected in parallel. The positive terminal of the first capacitor is connected to the output terminal of the pre-stage rectifier and filter circuit, and the positive terminal of the second capacitor is connected to the end of the constant current control circuit. The first inductor is connected in series between the positive terminals of the first capacitor and the second capacitor, and the negative terminals of the first capacitor and the second capacitor are grounded.

3. The EMI filtering power supply for a network communication product according to claim 2, characterized in that: The constant current control circuit includes a constant current drive chip, an output no-load voltage sampling circuit connected to the constant current drive chip, an absorption circuit connected to the constant current drive chip for absorbing the peak motor of the freewheeling diode, and a first safety capacitor for reducing interference in the circuit is provided between the ground pin of the constant current drive chip and the ground pin of the input / output network port circuit. The freewheeling diode is used to reduce electromagnetic interference in the circuit.

4. The EMI filtering power supply for a network communication product according to claim 3, characterized in that: The constant current driver chip is model KP23132M.

5. The EMI filtering power supply for a network communication product according to claim 3, characterized in that: The voltage across the first safety capacitor is less than or equal to 5V.

6. The EMI filtering power supply for a network communication product according to claim 1, characterized in that: The circuit board is equipped with a surge protection circuit, which is located between the mains power and the pre-stage rectifier and filter circuit.

7. The EMI filtering power supply for a network communication product according to claim 6, characterized in that: The surge protection circuit includes a varistor and a fuse resistor; The fuse resistor is connected in series at the positive input terminal of the pre-stage rectifier and filter circuit, and the varistor is connected in parallel between the positive and negative input terminals of the pre-stage rectifier and filter circuit.

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